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Plasma Processing and Processing Science Chapter 9 Conclusions and Recommendations RECOMMENDATION FOR A PROGRAM IN PLASMA PROCESSING AND PROCESSING SCIENCE As part of its long-term strategic planning process, the Naval Research Laboratory (NRL) has been considering establishing research programs in a number of areas with broad technological applications that address the needs of the nation, the missions of the Department of Defense, and those of the Navy. Plasma processing of materials is one such technology. At the request of NRL, the panel has addressed and in this report provided guidance on the following general questions: (1) What are some of the research opportunities in the field as a whole; (2) Does the existing NRL research capability in plasma physics, chemistry, surface science, and materials processing provide a sufficient base for building a focused research program that can address these opportunities; and, if so, (3) What other issues, such as outside collaborations, would need to be addressed? The panel finds that many opportunities exist for NRL to have significant impact on the use of plasmas in industrial manufacturing. In Chapter 2, Chapter 3, Chapter 4, Chapter 5, Chapter 6, Chapter 7 through Chapter 8, research opportunities are presented in the specific areas of modeling and simulation of plasma processing, semiconductor processing, plasma deposition and polymerization, ion implantation and surface modification, thermal plasmas, flat panel displays, and low-temperature plasmas. In view of the shifting emphasis in plasma physics away from high-temperature applications and toward low-temperature, industrial plasmas and based on its identification of selected opportunities in the field and its evaluation of NRL's research capabilities in plasma physics, chemistry, surface science, and materials processing, the panel recommends the following: The Naval Research Laboratory should develop a coordinated and focused program in plasma processing and processing science. The program should have the following features: The program should focus on a few emerging technologies, such as those drawn from the suggestions in Chapter 2, Chapter 3, Chapter 4, Chapter 5, Chapter 6, Chapter 7 through Chapter 8, on which NRL efforts could have a strong impact and for which NRL could strive to become a nationally recognized center. Each chapter includes a section entitled “A Role for NRL” that identifies research directions. In redirecting some of its resources to plasma processing and processing science, NRL should capitalize on its tradition of excellence in basic research by focusing the program on areas where it can be a national leader, without directly competing with industry or other established national programs on near-term objectives. NRL's emphasis on fundamental science should be maintained. By nature, plasma processing and plasma science are highly interdisciplinary fields. Therefore, collaboration among the existing groups at NRL in a focused research program is a prerequisite for success. The program should have a formalized structure, with its own director to ensure coordination among the groups, and include an ongoing seminar series with external speakers designed to facilitate cooperation, communication, and interest among the participants. The research program should be well balanced in terms of experimental and modeling efforts. It should strive toward establishing the knowledge base as well as the technology base for the chosen emerging technologies.
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Plasma Processing and Processing Science To establish and maintain contact with the mainstream of processing science, NRL should form collaborations with industry, universities, and other laboratories. NRL has had experience with setting up Cooperative Research and Development Agreements and could use these as mechanisms for accomplishing the goal of increased collaboration. (Chapter 2, Chapter 3, Chapter 4, Chapter 5, Chapter 6, Chapter 7 through Chapter 8 identify current academic, industrial, and federal laboratory efforts in the field.) It is the judgment of the panel that NRL has sufficient facilities in place to enable it to play a key role in many important issues pertaining to the plasma processing of semiconductors in ultralarge-scale integrated manufacturing. It is also the panel's judgment that the first priority for NRL should be to intensify interactions with the outside world to understand the current issues and to gain insight on where to focus its efforts. NRL personnel should increase their involvement with the materials processing community by attending relevant conferences, presenting contributed papers, and seeking invitations to give invited papers. CONCLUSIONS BASED ON NRL'S PRESENT RESEARCH CAPABILITIES The panel has the following specific conclusions on how NRL's capabilities could support the research program recommended above. The chemical vapor processing group is currently the best known and most active one in this field. Although it would be tempting to build the NRL materials processing effort around this group, a diversified program should not be dominated by any one group. This group should be one of several strong and active groups. This same group can provide in-depth treatment of surface chemical and gas-phase chemical issues. For example, selectivity is a key issue in gate conductor etching, and the group may be able to provide novel insights. A sophisticated diagnostics laboratory set up as a user facility will probably not attract interest from industry. Equipment manufacturers tend to do their testing in-house, partly to protect proprietary information. The NRL microfabrication facility can be used to process special devices such as measurement structures needed for sidewall passivation studies. NRL should not try to upgrade this facility, since it is highly unlikely that it can ever become a state-of-the-art fabrication line. The current emphasis on electron-cyclotron resonance (ECR) should be continued as an initial phase of NRL's entry into plasma processing. To complement the NRL diamond deposition work, it may make sense to focus on plasma-enhanced chemical vapor deposition for the present. NRL's effort is not big enough to be spread over many different applications. Its strongest asset seems to be its high degree of complementarity. This could be leveraged best by focusing on one key problem to make a significant impact. The ECR work of the ion/plasma processing group on diamond deposition is an ideal complement to the diamond work in the chemical vapor processing group. The ECR tool can be easily adapted to other materials and should be able to make significant contributions rapidly. At a later time, the use of alternate high-density plasma tools may be studied for diamond film deposition. The real-time diagnostics used in the Electronics Division could be important for the understanding of dry etch damage issues. Dry etch damage is clearly an important issue in gate conductor etching. This effort would benefit enormously by becoming part of a well-aimed overall effort on optical diagnostics, working together with the chemical vapor processing group.
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Plasma Processing and Processing Science The plasma modelers indicated that they would be able to treat the power absorption in ECR plasmas. This is an interesting issue, particularly with respect to the role the microwave coupling device plays (e.g., linear versus circularly polarized microwaves, and so on) and how the plasma nonuniformity affects wafer etch nonuniformity. After having established a degree of recognition and visibility, the modeling group can begin to compete on important current issues. In view of the anticipated increase in flat panel display production, NRL can take advantage of the opportunity to initiate research on the plasma problems in the fabrication of large-area displays. This industry is practically unaware of the benefits of improved plasma processing, and almost no work on this subject yet exists. NRL currently has at least one expert on display technology, and his experience can be utilized for this task. Waste destruction and conversion by plasma methods is a new field in which advances would benefit not only the Navy but also the general public. Within the context of NRL's scientific mission, however, one must try to find intellectually challenging problems in the chemical or plasma processes involved, rather than treat this as a brute-force engineering exercise. Diagnostics and sensors are also important in this industry. Though NRL has personnel with expertise in pulsed ion beams who can contribute to the field of ion or plasma implantation, the existing pulsed power equipment probably cannot be used effectively in plasma manufacturing. A new approach is needed here. Technical problems require technical solutions, and the microelectronics industry is no exception to this rule; however, even the best technical solutions can fail through human shortcomings in communication, planning, and program evaluation. To this end, it is further concluded that a companion personnel exchange program, under which NRL researchers could spend blocks of time at partner locations in industry and universities, and vice versa, would be invaluable in furthering NRL's contributions to the field. Activities such as this are generally necessary for effective communication, not only among industry, government, and universities, but even between different branches or divisions of the same company or armed service. In the successful Microelectronics Manufacturing Science and Technology program, cited elsewhere in this report, workers from Wright-Patterson Air Force Base conducted some work at their Dayton, Ohio, facility and also collaborated with Texas Instruments workers in Dallas, Texas. Despite the inevitable complications caused by temporarily relocating employees, the panel believes the benefits of long-term collaboration through these programs far outweigh the short-term difficulties of setting up relocation programs and shuttling employees. Additionally, the Office of Naval Research and NRL could together consider this important aspect of the Dual Use concept and its far-reaching benefits of one-on-one communication between government and industry.
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