Beam Technologies for Integrated Processing (1992) / Chapter Skim
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3 BEAM TECHNOLOGIES
3 BEAM TECHNOLOGIES
Pages 9-32
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From page 9... ...
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.
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From page 10... ...
The direct evaporation process, using electron beam or thermal evaporation techniques (see Figure 3-1) , has been successfuly used for preparing transition meal carbides, silicides' and borides (Maissel and Glang, 1970; Bubhani et al., 1984; Yokotsuka et al., 1987~.
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From page 11... ...
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.
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From page 12... ...
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.' 4A1 + 3O2 ~ 2AI2O3~. The reactive evaporation method has been used to synthesize films of SnO2, SnInO3, In2O3, A12O3, Sick, CUxMo6O~' Y2O3, and TiO2' and' more recently, YBa2Cu3O7 x-type perovskite superconductors.
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From page 13... ...
Reactive Sputtering Processes The tic 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.
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From page 14... ...
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 ~ second plasma near the substrate to activate the compound-forming reactions and combinations.
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From page 15... ...
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.
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From page 16... ...
16 Table 3-1 Ceramic Films Prepared by Reactive Ion Beam Sputtering Ceramic Compound | Beam Energy Target Material | Gases (keV) AIN ~ Dual beam ~ Al ~ Ar and N Ar+(1.5)
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From page 17... ...
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 additior~ 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)
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. 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.
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From page 19... ...
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.
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From page 20... ...
, 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 (Bubhani et al., 1984~. Apart from silicon nitride' the PACVD technique has been used to deposit a wide range of other ceramic materials.
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, 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)
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Table 3-3 Ceramic Materials Produced by CVD Coating Chemical Mixturc Deposition Temp.
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From page 23... ...
High rates of etching and deposition result from high plasma density, higher than in conventional reactive ion etching (RIE) and plasma deposition systems.
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From page 24... ...
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 1 Key)
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From page 25... ...
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.
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From page 26... ...
sources have been used extensively in industry for vacuum melting, evaporation, welding, surface conditioning, and machining since the late l950s; the initial applications were in welding and melting (Bakish, 1962; Bunshah and Cocca, 1968; Schiller et al., 19761. The electron beam is a very high efficiency energy source as compared to other sources such as lasers, radiation, and electromagnetic induction.
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From page 27... ...
, 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.
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From page 28... ...
Microwave Beams Microwave beams are not generally feasible power sources for use in normal processing schemes since the typical wavelengths (~) of 30- to 100-GHz energy (wavelengths of 1 cm to 3 mm, respectively)
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1988. A New Ultrafine Groove Fabrication Method Utlizing Electron Cyclotron Resonance Plasma Deposition and Reactive Ion Etching.
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From page 31... ...
1987. Low-Temperature Film Growth of Si by Reactive Ion Beam Deposition.
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