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Beam Technologies for Integrated Processing (1992)

Chapter: 3 BEAM TECHNOLOGIES

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Suggested Citation:"3 BEAM TECHNOLOGIES." National Research Council. 1992. Beam Technologies for Integrated Processing. Washington, DC: The National Academies Press. doi: 10.17226/2006.
×

3
BEAM TECHNOLOGIES

For the purpose of this report, beam technologies are defined as those involving directional transfer of matter or energy through a vacuum or the vapor phase. This chapter reviews the various beam technologies and focuses on the important operating principles of each. A summary table of many of these processes is found at the end of this chapter (Table 3-5). Applications to specific materials are reviewed in Chapters 4 and 5.

The sections that follow review various materials beam techniques used for processing. Physical vapor deposition (PVD), which includes both evaporation and sputtering as well as variations on these two fundamental processes, is examined. Molecular beam epitaxy (MBE), which is closely related to evaporation, is discussed next, followed by chemical vapor deposition (CVD). Included in the discussion of CVD are some variations such as plasma-assisted CVD and laser-assisted CVD. The use of microwave electron cyclotron resonance plasmas, a recent technique receiving much attention in semiconductor processing, is also reviewed. Ion beams are considered in a subsequent section. Energy beams, including laser, electron, x-ray, and microwave beams, are discussed in the last section of this chapter.

ATOMIC AND MOLECULAR MATERIAL BEAMS

Beam processes, such as PVD, CVD, electrodeposition, and MBE, are the primary processes considered below. All deposition processes consist of three steps: generation or supply of the depositing species, transport of the species from source to substrate, and film growth on the substrate. In some processes these steps can be controlled individually (e.g., in PVD, plasma spray, and MBE). In other processes the three steps occur simultaneously (e.g., in CVD processes). The versatility of a process depends on the ability to vary each of the three steps independently of the others. Furthermore, in plasma-assisted vapor deposition (PAVD) processes, the plasma parameters (electron density, electron energy, and electron energy distribution function) influence each of the three steps.

Physical Vapor Deposition

PVD processes consist of two fundamental classes of deposition techniques in which one or all constituents of the deposit are generated from a condensed source (solid or liquid) either by heat-induced vaporization (evaporation) or momentum transfer processes (sputtering). These can be either "direct" or "reactive" processes. Reactive processes are those that occur in the presence of a reactive gas so that a compound is formed in the gas phase or on the substrate surface. These processes are extensively covered in various books (Holland, 1966; Bunshah, 1982; Maissel and Glang 1970). Some are described briefly below.

Suggested Citation:"3 BEAM TECHNOLOGIES." National Research Council. 1992. Beam Technologies for Integrated Processing. Washington, DC: The National Academies Press. doi: 10.17226/2006.
×

Direct Evaporation Processes

The direct evaporation process is used extensively for metals and elemental semiconductors. In the case of ceramic materials, however, evaporation occurs with dissociation of the compound into fragments. In very few systems, such MgF2, B2O3, CaF2, SiC and some other group IV divalent oxides, evaporation occurs without dissociation. The stiochiometry of the deposit in a dissociation situation depends on the ratio of various molecular fragments striking the substrate, the sticking coefficient of the fragments striking the substrate (which may be a strong function of the substrate temperature), and the reaction rate of the fragments on the substrate to reconstitute the compound. In the case of ceramic systems, where one of the constituents is a gas in its elemental form, the films generally are deficient in the gaseous constituent (e.g., direct evaporation of Al2O3 results in a deposit deficient in oxygen). The imbalance of stoichiometry occurs to a lesser degree in ceramic systems where all the constituents are solids that have nearly the same vapor pressure in their elemental forms. The direct evaporation process, using electron beam or thermal evaporation techniques (see Figure 3-1 ), has been successfully used for preparing transition meal carbides, silicides, and borides (Maissel and Glang, 1970; Budhani et al., 1984; Yokotsuka et al., 1987). The slight variation in the stoichiometry of the coatings of such systems deposited by a single-source evaporation can be avoided if a multisource evaporation technique is used. A schematic diagram of a two-source evaporation process is shown in Figure 3-2. This technique is used quite extensively for the deposition of transition metal silicides (Hunter et al., 1978), as well as sulfides and selenides of group II elements (e.g., Zn and Cd).

Figure 3-1 Schematic of an evaporation-deposition process using electron  beam heating.

Suggested Citation:"3 BEAM TECHNOLOGIES." National Research Council. 1992. Beam Technologies for Integrated Processing. Washington, DC: The National Academies Press. doi: 10.17226/2006.
×

Figure 3-2 Schematic of the two-source evaporation process.

Flash evaporation is a very old method of depositing compounds, such as GaAs, PbTe, etc., whose constituents have a high vapor pressure and where it is important to maintain the stoichrometry of the deposit. In this technique, fine particles of the compound of the correct stoichrometry are sprinkled onto a heated surface (e.g., a tungsten strip at 2000°C). The particles are instantly and completely converted to the vapor phase (Maissel and Glang, 1970).

Laser ablation is a modern version of the flash evaporation process where a pulsed laser beam is used to locally heat a compound target and evaporate small discrete volumes in rapid succession, which preserves the stoichrometry of the deposit. The most important application is the deposition of thin films of high temperature superconducting oxides (e.g., YBa2Cu3O7-x). A major limitation of both of these is the small area of the deposit.

Direct Reactive Evaporation Processes

The reactive evaporation (RE) process is used to compensate for the loss of gaseous constituents of a ceramic during its direct evaporation. Thus, for example, stoichiometric Al2O3 films can be

Suggested Citation:"3 BEAM TECHNOLOGIES." National Research Council. 1992. Beam Technologies for Integrated Processing. Washington, DC: The National Academies Press. doi: 10.17226/2006.
×

deposited by direct evaporation of Al2O3 in an atmosphere of oxygen. However, because of the high melting point and the extreme reactivity of ceramic melts, it is generally difficult to evaporate ceramic materials. To avoid these problems, the reactive evaporation process is commonly used in a mode where the metallic constituent of the ceramic is evaporated in a partial pressure of the reactive gas to form a compound in the gas phase, or on the substrate, as a result of a reaction between the metal vapor and the gas atoms (e.g., ). The reactive evaporation method has been used to synthesize films of SnO2, SnInO3, In2O3, Al2O3, SiO2, CuxMo6O8, Y2O3, and TiO2, and, more recently, YBa2Cu3O7-x-type perovskite superconductors.

Since the reactive gas in the RE process is in a molecular state, and thus less likely to react with the vapor species, the formation of a well-crystallized stoichiometric film requires high thermal activation at the substrate. This problem becomes acute in situations where the reactive gas consists of more than one molecule; typical examples are SiH4 and CH4 or C2H2 for the formation of silicides and carbides. The concept of electron-impact ionization and excitation of the reactive gas in the substrate-source space (Bunshah and Raghuram, 1972) led to the solution of the problem. The ionization and excitation of the gas activates the compound-forming reactions, whereby the compound films can be synthesized at a much lower substrate temperature. This process is known as activated reactive evaporation (ARE) (see Figure 3-3).

Figure 3-3 Schematic of the activated reactive evaporation process.

Suggested Citation:"3 BEAM TECHNOLOGIES." National Research Council. 1992. Beam Technologies for Integrated Processing. Washington, DC: The National Academies Press. doi: 10.17226/2006.
×

Synthesis of TiC by reaction of Ti metal vapor and C2H2 gas atoms, using a carbon-to-metal ratio close to unity, was achieved with this process. Moreover, by varying the partial pressure of either reactant, the carbon-to-metal ratio of carbides could be varied at will. The ARE process has also been applied recently to the synthesis of all five different Ti-O oxides. The researchers (Bunshah and Raghuram, 1972) noted that in the ARE process (i.e., with a plasma), as compared to the RE process (i.e., without a plasma), a higher oxide was formed for the same partial pressure of O2, demonstrating a better utilization of the gas in the presence of a plasma.

A variation of the ARE process using a resistance-heated source instead of the electron-beam-heated source has been developed (Nath and Bunshah, 1980) and is particularly useful for evaporation of low-melting metals, such as indium and tin, where electron beam heating can cause splattering of the molten pool. The plasma is generated by low-energy electrons from a thermionically heated filament and is pulled into the reaction zone by an electrical field perpendicular to the evaporation axis. The ionization probability is further enhanced by a superimposed magnetic field that causes the electrons to go into a spiral path. This process has been used to deposit transparent conducting films of indium oxide and indium-tin oxide. The ARE process has several other variations (Bunshah and Deshpandey, 1987). The process has also been used in a dissociative mode, where instead of using an elemental evaporation source, a low-melting compound of the elements can be used. For example, cubic boron nitride films can be deposited by evaporating boric acid in an ammonia plasma (Bunshah and Deshpandey, 1987).

Direct Sputtering Processes

The basic sputter deposition process involves removal of atoms from the surface of a solid or liquid target by energetic ion bombardment and collection of the sputtered species on an adjacent solid substrate, as illustrated in Figure 3-4. A target, consisting of the material to be deposited, is held at a negative potential, ranging from a few hundred volts to a few kilovolts. For a critical value of the chamber pressure (from 1 × 10-3 to 0.1 Torr), application of the voltage initiates a plasma discharge in the vicinity of the target. The target, because of its negative potential, is bombarded by the ions present in the plasma. The plasma is sustained by stochastic ionization of the gas atoms or molecules by secondary electrons emanating from the target.

In situations where the gas ions are sufficiently heavy, bombardment of the target leads to sputtering of the target surface by a momentum transfer process. Argon, because of its high atomic number and nonreactivity, is the commonly used sputtering gas. Since the sputtering rate is directly dependent on the number of ions striking the target, its magnitude can be increased by increasing the ion density in the vicinity of the target. Higher ion densities can be achieved by application of magnetic fields. This modification of the sputtering process is known as magnetron sputtering. If the target material is electrically conducting, a direct current (dc) voltage can be used for sputtering. In the case of insulating targets, a radio frequency (rf) potential must be applied.

Reactive Sputtering Processes

The dc magnetron sputtering technique has been successfully used to deposit films of transition metal silicides and borides using a composite ceramic target. As in the case of evaporation, however, sputtering leads to dissociation of the target material into atoms and molecular fragments, which results in a deficiency of the gaseous constituents of the material. This off-stoichiometry problem can be eliminated by adding the constituent gas in the plasma along with the argon. This process modification is called reactive sputtering.

Suggested Citation:"3 BEAM TECHNOLOGIES." National Research Council. 1992. Beam Technologies for Integrated Processing. Washington, DC: The National Academies Press. doi: 10.17226/2006.
×

Figure 3-4

Schematic of a sputter-deposition process.

Plasma reactions of the gas with the target during reactive sputtering lead to formation of a compound layer on the target that slows the rate of sputtering. This phenomenon is known as target poisoning. Recently, many different approaches have been proposed to overcome the poisoning problem. They involve maintaining a composition gradient in the gas phase by injecting the reactive gas near the substrate where the film forms and maintaining the working gas for sputtering near the source; using getters to trap the reactive gas to reduce the amount reaching the target; using conductance-limiting baffles between the target and substrate; controlling the gas composition, relative to the metal sputtering rate, with the use of mass spectrometric sensors in a feedback mode; and creating a second plasma near the substrate to activate the compound-forming reactions and combinations.

A major modification of the reactive sputtering process has been introduced for depositing transition metal silicide films. The technique involves dc magnetron sputtering of the metal of interest in a silane-diluted argon plasma. Unlike the sputtering from a composite target, the process allows deposition of the silicides over a wide range of composition. This method differs from conventional reactive sputtering in the sense that one of the products of dissociation of the gas is a solid.

Suggested Citation:"3 BEAM TECHNOLOGIES." National Research Council. 1992. Beam Technologies for Integrated Processing. Washington, DC: The National Academies Press. doi: 10.17226/2006.
×

Recently, rf or dc reactive magnetron sputtering, employing a single ceramic target, has been used to deposit films of a large class of ceramic materials. It, nevertheless, suffers from some disadvantages:

  • The poor thermal conductivity of ceramics does not allow effective cooling of the target during sputtering, which results in local hot spots, with consequent spitting of the material and deposition of the particulates in the films. The ceramic targets also develop massive cracks after prolonged use.

  • In the case of multicomponent targets, such as those used for deposition of high temperature exide superconductors and tungsten bronzes, the preferrential sputtering of one of the components leads to a lack of stoichmetry in the films.

Ion Beam Sputtering Processes

In the basic ion beam sputtering process, an energetically well-characterized beam of inert gas ions, generated from an ion source, bombards the target to be sputtered. In the case of electrically insulating targets, neutral beams are used. The sputtered species are deposited on a substrate situated in a relatively high vacuum. If a metal target is used for the growth of a ceramic film, the reactive gas can be introduced directly in the discharge chamber of the ion gun or a separate gun can be used, as shown in Figure 3-5. Table 3-1 lists some ceramic systems that have been successfully deposited using ion beam and reactive ion beam deposition techniques.

Figure 3-5 Schematic of ion beam sputtering with reactive gas injection.

Suggested Citation:"3 BEAM TECHNOLOGIES." National Research Council. 1992. Beam Technologies for Integrated Processing. Washington, DC: The National Academies Press. doi: 10.17226/2006.
×

Table 3-1 Ceramic Films Prepared by Reactive Ion Beam Sputtering

Ceramic Compound

Beam Energy (keV)

Target Material

Gases

AlN

Dual beam Ar + (1.5), N2 + (0.8)

Al

Ar and N2 (separately)

 

Single beam (0.8-2.0)

Al

N2 + H2

BN

Ion source of B3N3H6

No target

B3N3H6

Si3N4

 

Si

Ar + N2

 

 

Si

Ar + N2 + H2

AlOxNy

Ar and N2 neutral beam

Al

Ar + N2 + O2 leak

SiOxNy

Ar and O2 neutral beam

Si

Ar + O2

In2(Sn)O3

Ar+ (0.5)

In/Sn alloy

Ar + O2

SnO2

Ar+

Sn

Ar + O2

A12O3

Ar+ (1.0)

Al

Ar + O2

Refractory Oxides

 

 

 

Y2O,3

 

 

 

TiO2,

Ar+

Refractory Metal

Ar + O2

Ta2O5

 

 

 

Refractory. Nitrides (e.g., NbN)

 

Nb

Xc + N2

Other materials

 

 

 

Lead zirconium titanate (PZT)

Ar+ (2.0)

Pb, Zr, Ti oxide ceramic

Ar + O2

YBa2Cu3O7

Ar+ (1.8)

YBa2Cu3O7-x oxide ceramic

Ar + O2

Suggested Citation:"3 BEAM TECHNOLOGIES." National Research Council. 1992. Beam Technologies for Integrated Processing. Washington, DC: The National Academies Press. doi: 10.17226/2006.
×

Molecular Beam Epitaxy

Many materials, ranging from semiconductors to metals and insulators, have been deposited as epitaxial (single-crystal) films by MBE. Molecular beam epitaxy is a term used to denote the epitaxial film deposition process involving the reaction of one or more thermal-molecular beams with a crystalline substrate surface under vacuum conditions (Parker, 1985). The conventional MBE process is related to vacuum evaporation, but in addition it offers very precise control over the incident atomic or molecular fluxes while the substrate is held at a precisely determined temperature (under ultrahigh vacuum conditions) to allow the formation of high-quality, single-crystal films. During the past two decades, multilayered composites that form heterostructures or periodic structures, called superlattices, have provided new degrees of freedom for device physicists and device engineers to obtain electrical or optical properties that could not be obtained from less complex naturally occurring materials.

The conventional MBE fluxes or beam formations are by evaporation of elemental materials from cylindrical effusion cells, as shown in Figure 3-6. In the case of growing gallium arsenide (GaAs), for instance, one effusion cell would be filled with pure gallium and the other with pure arsenic. The growth temperature may range from 550º to 700ºC (Cho, 1983). For the growth of

Figure 3-6 Schematic of a conventional MBE system.

Suggested Citation:"3 BEAM TECHNOLOGIES." National Research Council. 1992. Beam Technologies for Integrated Processing. Washington, DC: The National Academies Press. doi: 10.17226/2006.
×

silicon, high-temperature evaporation is required. Electron beam evaporation is generally used to achieve the high temperature for the growth of silicon. More recently, the beam flux has been generated by thermal decomposition of gaseous molecules, such as AsH3 and PH3 for obtaining arsenic and phosphorous atoms respectively (Panish and Temkin, 1989).

This gas-source MBE (GSMBE) has been most successful for the growth of quaternary materials, such as GaxIn1-xAsyP1-y, because the control of the phosphorous beam flux from a gas source is much better than that evaporated from solid phosphorus. For the modification of GSMBE using metalorganic gas sources, the names chemical beam epitaxy (CBE) and metalorganic MBE (MOMBE) have been introduced. A list of semiconductors grown with MBE is shown in Figure 3-7.

The typical growth rates of MBE are 1 to 5 µm/h. These growth rates are most suitable for the fabrication of electronic and optical devices, where the structures require precise thicknesses and where the desired total layer thickness is typically less than 1000 nm (l µm). The capability to grow single-crystal films with atomic-layer dimensional precision and with abrupt interfaces for complex structures makes MBE a unique crystal growth technology for the fabrication of future-generation microwave and optoelectronic devices. Since most semiconductor devices require at most only a few micrometer-thick epitaxial layers, the technique sometimes is commercially practical despite the low throughput. At present, multiwafer systems holding seven 2-in. or three 3-in. wafers are commercially available. The yield and uniformity (thickness variation of 1.5 percent over a 3-in. wafer) are the key factors for using MBE in production. It should be noted that MBE is not suitable for the growth of thick films in the millimeter range because of low deposition rates.

Figure 3-7 Semiconductors grown by MBE.

Suggested Citation:"3 BEAM TECHNOLOGIES." National Research Council. 1992. Beam Technologies for Integrated Processing. Washington, DC: The National Academies Press. doi: 10.17226/2006.
×

Chemical Vapor Deposition Processes

The use of volatile chemical intermediates to transport substances has been known since the latter half of the nineteenth century. While work on this technique has been ongoing since that time, only in the past 40 years has the method been extensively developed as a materials processing technique. Early work on crystal growth by CVD was done mostly in sealed ampules, but today the principal use of the technique is in flow systems (Figure 3-8).

Figure 3-8 Schematic of illustration of conventional CVD.

The transporting species may be presynthesized and transported under its own pressure or with a carrier gas, or it may be synthesized in situ by passing a reactive gas (such as HCl) over the material to be transported (e.g., a group III metal). The reactive gases are then brought together in a deposition zone, which is generally heated, where the reactions give the desired product. Depending on the conditions in the deposition zone (e.g., temperature, concentration, pressure, species, and flow rates), the deposition may vary from epitaxial growth on the substrate to formation of an ultrafine powder.

CVD has been used in the semiconductor industry for both preparation of high-purity, single-crystal layers and deposition of polycrystalline and glassy layers used in devices. Preparation of semiconductor-grade silicon involves production of volatile chlorosilane from impure silicon. The chlorosilane is purified by distillation. Silicon is produced by CVD of the chlorosilane onto a hot filament to yield polycrystalline silicon, which is then remelted and grown into single-crystal boules.

An attractive feature of CVD is that the chemical reactions involved in the process often occur at temperatures much below the melting (or decomposition) temperature of the material being prepared. Thus, it is possible to grow crystals of materials at temperatures below their melting point. This offers a significant advantage in preparing high-purity materials since contamination from the container or the system hardware is reduced at these lower temperatures.

The requirement for thermal dissociation in conventional CVD requires substrate temperatures in excess of 600ºC, in most cases, for any significant deposition to occur. The high substrate temperatures have both advantages and adverse effects on the properties of the films. Higher substrate temperatures promote the growth of a dense and well-crystallized structure with a minimum of trapped impurities. Also, since the dissociation reactions occur on the surface of the substrate itself, the conventional CVD process does not have the line-of-sight limitation of the PVD processes. With CVD, all parts of an irregularly shaped substrate are coated uniformly provided the temperature and gas flow conditions are the same everywhere. A wide class of oxides, borides, silicides, nitrides,

Suggested Citation:"3 BEAM TECHNOLOGIES." National Research Council. 1992. Beam Technologies for Integrated Processing. Washington, DC: The National Academies Press. doi: 10.17226/2006.
×

and carbides has been deposited by the conventional thermal CVD process. Some typical CVD reactions for the deposition of ceramics are listed in Table 3-2.

Table 3-2 Typical CVD Reactions for Depositing Ceramic Materials

Si (CH3) Cl3 (g) SiC (s) + 3HCl (g)

SiCl4 (g) + CH4 SiC (s) + 4HCl (g)

3SiH4 (g) + 4NH3(g) Si3N4 (s) + 12H2(g)

SiH4(g) + 2H2O(g) SiO2(s) + 4H2(g)

2A1Cl3(g) + 3CO2(g) + 3H2(g) A12O3(s) + 3CO(g) + 6HCl (g)

2Al(CH3)3(g) + 902(g) A12O3(s) + 6CO (g) + 9H2O(g)

Al(CH3)3(g) + NH3(g) AlN (s) + 3CH4 (g)

BCl3(g) + NH3(g) BN (s) + 3HCl (g)

SnCl4(g) + O2(g) SnO2 (s) + 2C12 (g)

Spray pyrolysis, a subcategory of thermally assisted CVD, involves the spraying of a solution, usually aqueous, containing soluble salts of the constituent atoms of the desired end compounds onto a heated substrate. A typical example of the spray pyrolysis process is deposition of tin oxide films by thermal dissociation of an alcoholic solution of SnCl4. In addition, preheating (temperatures between 200º and 500ºC) of the sprayed droplets can be used to ensure vaporization of the reactants before they undergo a heterogeneous reaction at the substrate. The technique is very simple and is adaptable for mass production of large-area coatings in industrial applications. Various geometries of the spray setups are employed, including an inverted arrangement in which larger droplets and gas-phase precipitates are discouraged from reaching the substrate; the results are films of better quality. This technique has been used extensively to deposit films of ZnO, In2O3, SnO2, CdS, Al2O3, and other ceramic systems.

The higher deposition temperatures required in a CVD process have adverse effects in situations where the substrate is susceptible to temperature-induced irreversible structural or electrical changes. This type of problem is encountered when depositing dielectric coatings on previously processed electronic devices or substrates. However, low—temperature CVD of ceramic coatings can be realized by plasma-assisted CVD (PACVD) processes using either rf or dc glow discharge plasmas (see Figure 3-9).

One of the most common examples of PACVD processes is the growth of silicon nitride from a mixture of SiH4 and NH3 gases. In this particular case, the electron-impact dissociation of silane and ammonia leads to the following fragments:

The reaction between the nitrogen-and hydrogen-containing species in the plasma results in a solid deposit commonly written as SixN1-x :H. The physical properties (e.g., electrical conductivity, optical absorption, refractive index), the Si/N ratio, and the stress state of the plasma CVD-prepared silicon nitride are highly sensitive to the amount of bonded hydrogen in the material and the degree of ion bombardment during film growth (Budhani et al., 1984). Apart from silicon nitride, the PACVD technique has been used to deposit a wide range of other ceramic materials.

To avoid ion bombardment of the growing film in a parallel-plate PACVD process, a process modification has been introduced in which the substrates are placed away from the plasma. The technique is known as remote PACVD.

Suggested Citation:"3 BEAM TECHNOLOGIES." National Research Council. 1992. Beam Technologies for Integrated Processing. Washington, DC: The National Academies Press. doi: 10.17226/2006.
×

Figure 3-9 Schematic illustration of plasma-assisted CVD: (A) rf glow  discharge, (B) dc glow discharge

Another technique now being investigated is laser-assisted CVD (LACVD), which may be carried out in two ways. In one use, the laser heats the substrate locally where deposition is desired, and, by controlling the general substrate temperature to below that where deposition occurs, selective growth of the depositing species can be achieved. Alternatively, the laser may be of a wavelength that excites one of the gaseous species causing reaction of that species; then, by shining the laser through the gas close to the substrate surface, deposition may be induced on the surface. A listing of some ceramic materials produced by CVD (also CCVD), with the deposition temperature and precursor molecules, is given in Table 3-3.

Microwave Electron Cyclotron Resonance Plasmas

In the past several years electron cyclotron resonance (ECR) plasmas have become increasingly attractive for semiconductor processing (Yamada and Torii, 1987). In addition, these plasmas may be used for deposition of SiO2 Si3N4, and SiC (Ohki et al., 1988). Initially, they were used in ion

Suggested Citation:"3 BEAM TECHNOLOGIES." National Research Council. 1992. Beam Technologies for Integrated Processing. Washington, DC: The National Academies Press. doi: 10.17226/2006.
×

Table 3-3 Ceramic Materials Produced by CVD

Coating

Chemical Mixture

Deposition Temp. (ºC)

Method

Applicationa

 

 

CARBIDES

 

 

TiC

TiCl4-CH4-H2

900-1000

CCVD

wear

 

TiCl4-CH4(C2-H2)-H2

400-600

PACVD

elec

HfC

HfClx-CH4-H2

900-1000

CCVD

wear, cor, ox

ZrC

ZrCl4-CH4-H2

900-1000

CCVD

wear, cor, ox

 

ZrBr4-CH4-H2

>900

CCVD

wear, cox, ox

SiC

CH3SiCl3-H2

1000-1400

CCVD

wear. cor, ox

 

SiH4-Cx-Hy

200-500

PACVD

elec, cor

B4C

BCl3-CH4-H2

1200-1400

CCVD

wear

B2C

B2H6-CH4

400

PACVD

wear. elec. cor

W2C

WF6-CH4-H2

400-700

CCVD

wear

Cr7C3

CrCl2-CH4-H2

1000-1200

CCVD

wear

Cr3C2

Cr(CO)6-CH4-H2

1000-1200

CCVD

wear

TaC

TaCl5-CH4-H2

1000-1200

CCVD

wear, elec

VC

VCl2-CH4-H2

1000-1200

CCVD

wear

NbC

NbCl5-CCl4-H2

1500-1900

CCVD

wear

 

 

NITRIDES

 

 

TiN

TiCl4-N2-H2

900-1000

CCVD

wear

 

TiCl4-N2-H2

250-1000

PACVD

elec

HfN

HfClx-N2-H2

900-1000

CCVD

wear. cor, ox

 

Hfl4-NH4-H2

>800

CCVD

wear. cor, ox

Si3N4

SiCl4-NH3-H2

1000-1400

CCVD

wear. cor, ox

 

SiH4-NH3-H2

250-500

PACVD

elec, cor, ox

 

SiH4-N2-H2

300-400

PACVD

elec

BN

BCl3-NH3-H2

1000-1400

CCVD

wear

 

BCl3-NH3-H2

25-1000

PACVD

elec

 

BH3N(C2-H5)3-Ar

25-1000

PACVD

elec

 

B3N3H6-Ar

400-700

CCVD

elec, wear

 

BF3-NH3-H2

1000-1300

CCVD

wear

 

B2H6-NH3-H2

400-700

PACVD

elec

ZrN

ZrCl4-N2-H2

1100-1200

CCVD

wear, cor, ox

 

ZrBr4-NH3-H2

>800

CCVD

wear. cor, ox

TaN

TaCl5-N2-H2

800-1500

CCVD

wear

AIN

AlCl3-NH3-H2

800-1200

CCVD

wear

 

AIBr3-NH3-H2

800-1200

CCVD

wear

 

AIBr3-NH3-H2

200-800

PACVD

elec, wear

 

Al(CH3)3-NH3-H2

900-1100

CCVD

elec. wear

VN

VCl4-N2-H2

900-1200

CCVD

wear

NbN

NbCl5-N2-H2

900-1300

CCVD

wear. elec

 

 

OXIDES

 

 

Al2O3

AlCl3-Co2-H2

900-1100

CCVD

wear, cor, ox

 

Al(CH3)3-O2

300-500

CCVD

elec, cor

 

Al[OCH(CH3)2]3-O2

300-500

CCVD

elec, cor

 

Al(OC2H5)3-O2

300-500

CCVD

elec, cor

SiO2

SiH4-CO2-H2

200-600

PACVD

elec, cor

 

SiH4-N2O

200-600

PACVD

elec

TiO2

TiCl4-H2O

800-1000

CCVD

wear. cor

 

TiCl4-O2

25-700

PACVD

elec

 

Ti[OCH(CH3)2]4-O2

25-700

PACVD

elec

ZrO2

ZrCl4-CO2-H2

900-1200

CCVD

wear. cor, ox

TarOs

TaCl5-O2-H2

600-1000

CCVD

wear. cor, ox

Cr2O3

Cr(CO)6-O2

400-600

CCVD

wear

 

 

BORIDES

 

 

TiB2

TiCl4-BCl3-H2

800-1000

CCVD

wear. cor, elec

MoB

MoCl5-BBr3

1400-1600

CCVD

wear, cor

WB

WCl6-BBr3-H2

1400-1600

CCVD

wear, cor

NbB2

NbCl5-BCl3-H2

900-1200

CCVD

wear, cor

TaB2

TaBr5-BBr3

1200-1600

CCVD

wear, cot

ZrB2

ZrCl4-BCl3-H2

1000-1500

CCVD

wear, cor, elec

HfB2

HfClx-BCl3-H2

1000-1600

CCVD

wear, cor

SOURCE: Stinton et al. (1988).

a elec, electronics; cor, corrosion-resistant coatings; wear, wear-resistant coatings; ox, oxidation-resistant coatings.

Suggested Citation:"3 BEAM TECHNOLOGIES." National Research Council. 1992. Beam Technologies for Integrated Processing. Washington, DC: The National Academies Press. doi: 10.17226/2006.
×

sources for nuclear fusion plasmas and particle beam physics, but work in Japan in the early 1980s demonstrated their promise for improved etching and deposition. There is now rapidly expanding research and development work on processing applications using ECR, and a growing number of commercial suppliers of ECR sources and systems can be found in the United States, Japan, and Western Europe.

Microwave ECR occurs when a plasma is excited by 2.45 GHz microwave radiation in a 875 gauss (G) magnetic field. Microwave energy is absorbed efficiently because the electron cyclotron frequency equals the microwave frequency. Electrons are confined by the magnetic field, leading to a high-density plasma (1010 to 1012/cm3) and a high degree of dissociation of the molecular gases. This electron confinement enables stable ECR plasmas to be sustained at pressures from 10-3 to about 10-5 Torr (compared to diode plasmas requiring 0.1 Torr or magnetron plasmas requiring 0.01 Torr).

ECR systems appear to be well suited for the coming generations of single-wafer processing systems. High rates of etching and deposition result from high plasma density, higher than in conventional reactive ion etching (RIE) and plasma deposition systems. Excellent etch anisotropy is provided by low-pressure operation, and low material damage and high etch selectivity are obtainable because ions strike the wafer with low energy. Reactive gases are handled easily since there is no cathode or filament and source gases are utilized efficiently, providing economy and minimizing effluent to the environment. Because ECR works best at low pressures, it is well suited for integration with inherently ultrahigh vacuum processes such as MBE.

Among the disadvantages or complications of ECR processing are the intense UV radiation environment, which may damage devices; the effects of fringing magnetic fields on other equipment; safety concerns about microwave leakage; and the relatively high cost of equipment, including large vacuum pumps to handle high gas throughput at low pressure. Although uniformity over large wafers remains a concern, recent work has demonstrated improved uniformity by controlling the shape of the magnetic field with magnets on both sides of the wafer (e.g., Figure 3-10).

Figure 3-10 Schematic of a diverging-field ECR system.

Suggested Citation:"3 BEAM TECHNOLOGIES." National Research Council. 1992. Beam Technologies for Integrated Processing. Washington, DC: The National Academies Press. doi: 10.17226/2006.
×

At least three ECR source designs are now common: (1) diverging magnetic field systems, in which electrons stream from the source along magnetic field lines and low-energy ions are extracted by the resulting electric field. Ion energies from this source have been measured in the range of 50 eV and below. (2) Ion beam systems, in which a set of grids extract a beam of ions from the ECR plasma region. Operation of these systems is similar to that of conventional reactive ion beam etching (RIBE) systems. (3) Distributed ECR (DECR) systems, in which ECR regions are set up around the periphery of a chamber by microwave antennae that are positioned close to a multipolar set of magnets. The resulting ions and radicals diffuse to a wafer placed in the center of the chamber.

Many uses of ECR processing have been demonstrated successfully. Among the most successful are etching of Si and SiO2 with fluorocarbons and etching of GaAs, AIGaAs, and InP with chlorine (Cl2) and other chlorine-containing molecules. Radio frequency bias of the substrate was used in some of this work to provide independent control of ion energy. Dielectrics have been deposited at high rates, including, for example, deposition of SiO2 from gas mixtures such as SiH4 and O2 and deposition of silicon nitride from SiH4 and NH3. Silicon has been grown epitaxially from SiH4 below 650ºC, after in situ surface cleaning by ion sputtering with ions from the same ECR source or by reaction with active species from a hydrogen (H2) ECR plasma. Various metals have been deposited by using argon ions from an ECR plasma to sputter metals from targets arranged coaxially or in front of the ECR source.

Ion Beams

Ion beams are of particular interest from the point of view of attaining a fully integrated processing system. They are commonly used for processing semiconductor wafers and in some cases have already been integrated with other processing equipment. In addition, the technology is ideally suited for modifying surface properties of materials in a wide variety of applications, ranging from biomaterials to aerospace applications. For classification purposes, ion beams can be divided into the following three categories:

  • Low-energy ion beams (below I KeV) are used mostly for modifying the interfaces of materials (e.g., for etching, changing the surface energy, improving the adhesion of a surface) and in many applications are accompanied by deposition or removal processes.

  • Medium-energy ion beams (10 KeV to 1 MeV) are used for modifying surfaces and interfaces of metals, ceramics, and polymers. (This energy range also includes ion implantation, diagnostic procedures such as SIMS, and ion beam lithography.)

  • High-energy (over 1 MeV) ions are used for the production of radionuclides for nuclear medicine, diagnostic monitoring in industrial applications, and characterization of surfaces (e.g., Rutherford backscattering).

Beams of practically any ion species can be created. The most common species for semiconductor applications are B, P, As, Sb, Ga, BF3, Si, and Ge. For treatment of nonsemiconductors, the common species are N, C, Ti, Cr, P, Mo, Y, Ar, and Ta. For the production of radionuclides, the most common ions are light species such as H and He.

Suggested Citation:"3 BEAM TECHNOLOGIES." National Research Council. 1992. Beam Technologies for Integrated Processing. Washington, DC: The National Academies Press. doi: 10.17226/2006.
×

Energy Beams

Important characteristics and unique features of some beams as energy sources are reviewed briefly in this section, particularly lasers, electron beams, x-rays, electromagnetic induction, and microwaves. These discussions help in understanding how each is being applied or is being developed for manufacturing schemes.

Laser Beams

The features of lasers are sufficiently attractive and unique to merit explanation of their development as processing tools. Consider, for example, the following features: (1) lasers are intense sources of directed energy, (2) laser irradiation can be carried out in a variety of atmospheres, (3) lasers produce effects that are very localized in space and time, and (4) the motion of the laser beam relative to the workpiece can be easily automated. These features, along with the commercial development of reliable lasers suitable for the industrial environment, have led to their widespread use in manufacturing and materials processing (Duley, 1983).

The development of lasers as processing tools has created new opportunities for attaining fully integrated processing systems (Bass, 1983). Owing to the high-intensity characteristic of focused laser beams, their effects often require only short interaction times. Thus, substitution of a laser processing step for the slow processing step in a continuous flow or transfer station system may be an effective strategy for improving productivity. In contrast to electron beam processes, laser beam processes do not require a vacuum environment and can be carried out in a variety of reactive or protective atmospheres. The ease with which the motion of a laser beam can be controlled and automated facilitates its use in flexible manufacturing systems. The noncontacting characteristic of laser beams leaves clearance around the workpiece, where sensors can be placed for on-line inspection and process control.

Three important characteristics of lasers for use as tools in fully integrated processing systems are their spatial distribution of intensity, their temporal distribution of intensity, and their wavelength. The amount of energy deposited in a region per interval of time determines the temperature change and thus the effect on materials. The distribution of intensity in space and time also determines the degree of localization of the effect. The spatial distribution of intensity delivered by the laser depends on the mode of the laser; it can be highly localized with a three-dimensional Gaussian-type distribution (TEM00 mode) or more spread out with a ''top-hat''-type distribution (TEM10 mode). The temporal distribution can be a continuous wave (cw) or pulsed, with a variety of wave shapes and duty cycles possible.

Lasers are monochromatic; the wavelength of a particular type of laser is perhaps the most important factor in selecting it for a particular application. Wavelength determines the extent to which laser energy is absorbed, transmitted, and reflected by a specific material. Since the laser is normally used as a heat source, the beam must be absorbed by the workpiece material. The wavelength also determines the materials used in the optical path and thus affects the ease and efficiency with which the beam can be brought to the workpiece. For a particular focal-length lens, the wavelength also determines the focused spot size of the laser beam and hence the average intensity and degree of resolution possible in a particular process. The lasers used most often in materials and manufacturing processes are the CO2, Nd-YAG, and excimer lasers. Some of their characteristics are listed in Table 3-4.

Suggested Citation:"3 BEAM TECHNOLOGIES." National Research Council. 1992. Beam Technologies for Integrated Processing. Washington, DC: The National Academies Press. doi: 10.17226/2006.
×

Table 3-4 Laser Characteristics

Laser

Wavelength

cw or pulsed

CO2

10.60 µm

cw or pulsed

Nd-YAG

1.60 µm

cw or pulsed

Excimer

 

 

ArF

193 nm

pulsed

KrF

248 nm

pulsed

XeCl

308 nm

pulsed

XeF

351 nm

pulsed

Electron Beams

High-power electron beam (EB) sources have been used extensively in industry for vacuum melting, evaporation, welding, surface conditioning, and machining since the late 1950s; the initial applications were in welding and melting (Bakish, 1962; Bunshah and Cocca, 1968; Schiller et al., 1976). The electron beam is a very high efficiency energy source as compared to other sources such as lasers, radiation, and electromagnetic induction. The following advantages are identified:

  • Heat can be applied to any defined area on the surface of the material to be heated.

  • Extremely high power inputs can be concentrated into a very small area.

  • Power density requirements vary for different applications, as shown below:

Application

Approximate Power Density Range (W/cm2)

Annealing

102-103

Melting

103-105

Evaporation

104-107

Welding

106-108

Machining (metal removal) up to 109

 

Note: By comparison, power densities of about 104 W/cm2 and 105 W/cm2 are available from the oxyacetylene flame and the electric arc, respectively. It should be noted that in most of the highest-current and high-power-density electron beam machines existing today, the power density is not space charge limited but is limited by the temperature of the cathode and the quality of the electron optics.

  • No medium is needed to transfer energy from the source to the material to be treated, as, for example, in gas flames and electric arcs.

  • Heating is carried out in high vacuum, thereby almost inherently providing a reasonably clean environment.

Suggested Citation:"3 BEAM TECHNOLOGIES." National Research Council. 1992. Beam Technologies for Integrated Processing. Washington, DC: The National Academies Press. doi: 10.17226/2006.
×
  • If crucibles are used for containing the material being processed, in many cases they are made from water-cooled copper, thus avoiding contamination from the ceramic crucible material liner. In some cases, crucible liners of other materials are used.

  • Conversion of electron energy to heat in the material being bombarded is very efficient.

  • Power can be applied and controlled independent of melting rate (in contrast to consumable-electrode arc melting), which allows melting and superheating of the materials at a rate consistent with its impurity content to effect optimum refinement.

  • Beam intensity, focus, shape, and position are controllable precisely and almost instantaneously, which makes programming an electron beam process, such as machining, straight forward.

A gun system must consist of at least two elements—a cathode and an anode. Additionally, there are electrostatic or electromagnetic systems to focus and scan the beam. A dual classification system is used for such sources:

  • Classification I

    • Work-accelerated, where the anode is the workpiece.

    • Self-accelerated, where the anode is part of the gun structure and is located fairly close to the cathode. Electrons emitted by the cathode are accelerated by the potential difference between the cathode and the anode, pass through a hole in the anode and continue onward to strike the grounded workpiece.

  • Classification II

    • Electrons are produced from the cathode by:

      • thermionic emission from metal surfaces

      • extraction from a localized or confined plasma.

Any combination of the above classifications is possible—for example, a work-accelerated plasma EB source, or a self-accelerated thermionic gun. Thermionic EB guns are further subdivided into the following types: close cathode, distant cathode, Pierce-type, and transverse linear cathode. Plasma EB guns are further classified into the following two types: cold cathode (Stauffer and Cocca, 1963) and hot hollow cathode (Morley, 1963).

Comparisons between thermionic and plasma EB guns can be made. A thermionic EB gun filament assembly must be kept at pressures less than 10-3 Torr to keep discharges to a minimum since very high voltages are used (3 to 200 kV). This requires a differentially pumped chamber with the beam extracted through a hole in the pressure-isolation wall. The beam power can go from very low (a few watts) to very high (up to 1.2 Mw) power. Plasma EB guns do not operate at very high power levels but can be used at pressures up to 0.1 Torr, thus eliminating the need for a differentially pumped chamber.

Cathode erosion by sputtering caused by ion bombardment is common to all types of guns, thus becomes the lifetime-limiting factor. All guns, except the cold cathode gun, need or may benefit from beam focusing and deflection.

Suggested Citation:"3 BEAM TECHNOLOGIES." National Research Council. 1992. Beam Technologies for Integrated Processing. Washington, DC: The National Academies Press. doi: 10.17226/2006.
×
X-Ray Lithography

As optical lithography moves into the 0.35-μm to 0.25 μm pattern size range, the limits of its capability are approached. X-ray lithography offers a high-throughput solution to the submicrometer pattern regime below this value. In addition, better resolution, reduced impact from particulates, and greater depth of focus are x-ray lithography's main features. However, the technology is complicated by a number of unsolved problems, including mask materials, resists, and x-ray sources.

A mask for x-ray lithography is a very thin membrane (less than 5 μm) of a low atomic number material with a high atomic number absorber material defining the pattern. This mask must be transparent to x-rays and flat with minimal distortion. Production-scale fabrication of masks is still more a goal than a reality. The resists for x-ray lithography also present difficulties for good resolution, sensitivity, and contrast, while still retaining resistance to dry etching. Resist development has resulted in significant progress, but considerably more is needed for moving the technology into manufacturing.

X-ray sources themselves have presented the most significant problem; x-ray tubes, lasers, plasma sources, and storage rings have been investigated. In Japan a number of x-ray lithography centers based on synchrotrons are under development. The brightest sources are the synchrotrons, which emit collimated beams—an advantage in minimizing the penumbral blur that occurs when uncollimated beams intersect mask structures and cast wider shadows on the target. These systems are, however, large and very expensive.

Synchrotrons can be integrated readily with the rest of the fabrication process, in that the beam lines connect it into the clean room where the remainder of the manufacturing occurs. Much of the focus today is on the development of more compact x-ray systems. In the United States, IBM stands out among chip manufacturers for aggressively pursuing next-generation x-ray technology. A compact synchrotron ring is being installed at IBM's East Fishkill (N.Y.) facility, which will be open for a fee to other U.S. chip manufacturers. It should be noted that a number of other lithographic techniques (e.g., E-beam, ion-beam, deep-UV) have been and are still being examined for fine-line pattern size applications and offer important alternatives in this area.

Microwave Beams

Microwave beams are not generally feasible power sources for use in normal processing schemes since the typical wavelengths (γ) of 30- to 100-GHz energy (wavelengths of 1 cm to 3 ram, respectively) would require optics with apertures of several feet to collimate a useful high-intensity energy beam. Microwave energy can be concentrated, however, in small waveguides and cavities of various sizes, and processing can be accomplished inside such waveguides and cavities. Typical rectangular waveguide cross-sections are approximately γ/2 by γ/4 (e.g., at 10 GHz a waveguide of about 1.3 by 2.5 cm and a cavity of about 5 to 7.5 cm wide and 7.5 cm high).

Microwave generators capable of intermittent high power have been available for about 50 years. Pulse powers of several megawatts can be generated by magnetrons developed for radar applications, but pulse lengths are short and average power is in the kilowatt range. For continuous power, klystrons and gyrotrons, developed for electronic countermeasures, heating, and communications, provide continuous power in the hundred kilowatt range at some frequencies. The major limitation in the development of higher-power devices is in the electron generation area, where hot cathode techniques are limited and the problem of removal of high thermal loads from the normal losses in high-power electron tube devices. High voltages in small geometries also present problems (Sutton, 1988).

Suggested Citation:"3 BEAM TECHNOLOGIES." National Research Council. 1992. Beam Technologies for Integrated Processing. Washington, DC: The National Academies Press. doi: 10.17226/2006.
×

Table 3-5 Selected Characteristics of Some Beam Deposition Processes

 

Evaporation

Ion Plating

Sputtering

Chemical Vapor Deposition

Thermal Spraying

Mechanism of production of depositing series

Thermal energy

Thermal energy

Momentum transfer

Chemical reaction

From flames or plasmas

Deposition rate

Can be very high (up to 750,000 Å/min)

Can be very high (up to 250,000 Å/min)

Low except for pure metals (e.g. Cu-10,000 Å/min)

Moderate (200-2,500 Å/min)

Very high

Depositing specie Throwing power for:

Atoms and ions

Atoms and ions

Atoms and ions

Atoms

Dropless

a: Complex shaped object

Poor line-of-sight coverage except by gas scattering

Good; but non-uniform thickness distribution

Good; but non-uniform thickness distribution

Good

Poor

b: Into small blind holes

Poor

Poor

Poor

Limited

Very limited

Metal deposition

Yes

Yes

Yes

Yes

Yes

Alloy deposition

Yes

Yes

Yes

Yes

Yes

Refractory compound deposition

Yes

Yes

Yes

Yes

Yes

Energy of depositing species

Low ~0.1 to 0.5 eV

Can be high (1-100 eV)

Can be high (1-100eV)

Can be high with plasma-aided CVD

Can be high

Bombardment of substrate/deposit by inert gas ions

Not normally

Yes

Yes or no depending on geometry

Possible

Yes

Growth Interface perturbation

Not normally

Yes

Yes

Yes (by rubbing)

No

Substrate heating (by external means)

Yes, normally

Yes or no

Not generally

Yes

Not normally

 

Source: Bunshah and Raghuram, 1972.

Suggested Citation:"3 BEAM TECHNOLOGIES." National Research Council. 1992. Beam Technologies for Integrated Processing. Washington, DC: The National Academies Press. doi: 10.17226/2006.
×

REFERENCES

Bakish, R. F. 1962. Introduction to Electron Beam Technology. John Wiley & Sons, New York.

Bass, M. 1983. Laser Materials Processing. Materials Processing Theory and Practices. F. F. Y. Wang, Series Ed., Vol. 3. North-Holland Publishing Co., New York.

Budhani, R. C., M. Memerian, H. J. Doerr, C. V. Deshpandey, and R. F. Bunshah. 1984. Microstructure and Mechanical Properties of TiC-Al 2O3 Coatings. Thin Solid Films, 118:293.

Bunshah, R. F. (ed.). 1982. Deposition Technologies and Their Applications. NOYES Publications, New York.

Bunshah, R. F., and M. A. Cocca. 1968. Electron Beam Melting, Annealing and Distillation. Techniques of Metals Research, Vol. 1, Part 2, p. 717. Interscience Publishers, New York.

Bunshah, R. F., and C. V. Deshpandey. 1987. The Activated Reactive Evaporation Process. Physics of Thin Films. Vol. 13, p. 59. Academic Press, New York.

Bunshah, R. F., and A. C. Raghuram. 1972. The Activated Reactive Evaporation Process. Journal of Vacuum Science and Technology 9:1385.


Cho, A. Y. 1983. Growth of III-V Semiconductors by Molecular Beam Epitaxy. Thin Solid Films 100:291-317.


Duley, E.W. 1983. Laser Processing and Analysis of Materials. Plenum Press, New York.


Holland, L. 1966. Vacuum Deposition of Thin Films. Chapman and Hall, London.

Hunter, W. R., L. Ephrath, W. D. Godoman, C. M. Osburn, B. L. Crowder, A. Cramer, and H. E. Luhn. 1978. 1 µm MOSFET VLS Technology. Part V. A Single Level Polysilicon Technology. IEEE Transactions on Electron Devices RD26:353.


Maissel, L. I., and R. Glang. 1970. Handbook of Thin Film Technology. McGraw-Hill Book Co., New York.

Morley, J. R. 1963. Hollow Cathode Discharge Beams in Vacuum Processing. Transactions of the Vacuum Metallurgy Conference. American Vacuum Society. Vol. 4:186. New York.


Nath, R., and R. F. Bunshah. 1980. Preparation of In2O3 and Tin-Doped In2O3 Films by a Novel Activated Reactive Evaporation Technique. Thin Solid Films 69:63.


Ohki, S., M. Oda, and T. Shibata. 1988. A New Ultrafine Groove Fabrication Method Utlizing Electron Cyclotron Resonance Plasma Deposition and Reactive Ion Etching. Journal of Vacuum Science and Technology. Vol. 27:533-536.


Panish, M. B., and H. Temkin. 1989. Gas-Source Molecular Beam Epitaxy. Annual Reviews of Materials Science 19:209-229.

Parker, E. H. C. 1985. The Technology and Physics of Molecular Beam Epitaxy. Plenum Press, New York.

Suggested Citation:"3 BEAM TECHNOLOGIES." National Research Council. 1992. Beam Technologies for Integrated Processing. Washington, DC: The National Academies Press. doi: 10.17226/2006.
×

Schiller, S., U. Heisig, and S. Panzer. 1976. Electronsthral Technology. Veb Verlag Technik, Berlin.

Stauffer, L. H., and M. A. Cocca. 1963. The Plasma Electron Beam Source and Its Application to Vacuum Metallurgy. Transactions of the Vacuum Metallurgy Conference, American Vacuum Society, Vol 1:203.

Stinton, D. P., T. M. Besmann, and R. A. Lowden. 1988. Advanced Ceramics by Chemical Vapor Deposition Techniques. American Ceramic Society Bulletin 67(2):350.

Sutton, W. H. (ed.). 1988. Microwave Processing of Materials. Materials Research Society Symposium Proceedings, Vol. 124. Materials Research Society, Pittsburgh, Pa.


Yamada, H., and Y. Torii. 1987. Low-Temperature Film Growth of Si by Reactive Ion Beam Deposition. Applied Physics Letters 50:386-388.

Yokotsuka, T., T. Narusawa, Y. Uchida, and H. Nakashima. 1987. X-ray Photoelectron Spectroscopy Study of Schotthy Barrier Formation and Thermal Stability of LaB6-GaAs(001)C(4x4) Interface. Applied Physics Letters 50:591.

Suggested Citation:"3 BEAM TECHNOLOGIES." National Research Council. 1992. Beam Technologies for Integrated Processing. Washington, DC: The National Academies Press. doi: 10.17226/2006.
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Beam technologies play an important role in microelectronic component fabrication and offer opportunities for application in other manufacturing schemes. Emerging beam technologies that incorporate potential for sensors, control, and information processing have created new opportunities for integrated processing of materials and components.

This volume identifies various beam technologies and their applications in electronics and other potential manufacturing processes. Recommendations for research and development to enhance the understanding, capabilities, and applications of beam technologies are presented.

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