Faculty of Systems Science and Engineering, Kansai University
The official name of ADMETA, Advanced Metallization Conference: Asian Session, has been used approximately since 1991. Earlier, its official name was the Tungsten and Other Advanced Metals for VLSI/ULSI Application, and the first tungsten workshop was held in Japan in 1989. This workshop (the sixth tungsten workshop) was simultaneously held in Japan and the United States.
The Tungsten Workshop was a conference established by Dr. Blewer of the Sandia National Laboratories in the United States, held first time in the fall of 1984 at Sandia National Laboratories in Albuquerque, New Mexico. It was a small closed workshop. At that time, LSI interconnect technology was still about Al 2-layer interconnect, and there was a significant interest in tungsten selective growth technology using LPCVD (Low-Pressure Chemical Vapor Deposition), which was expected to be applied to multi-layer interconnects or gates. Moreover, the 1st VMIC (VLSI Multilevel Interconnection Conference) was organized by the IEEE in the spring of 1984, when the popularity for multi-layered LSI inteconnect was increasing. The 2nd tungsten workshop was held in 1985 at Albuquerque, in which Mr. Takahiko Moriya (Toshiba) and Mr. Naoki Yamamoto (Hitachi) from Japan participated. The proceedings of the first and second workshops were combined into one volume and published by the Materials Research Society (MRS) as “Red Book” published in the spring of 1986. Since then, workshops have been held every year, and Red Book had been published by MRS. Moreover, the number of Japanese participants had increased, and the interest of the US in Japanese tungsten CVD technology had also expanded.
In March 1988, the first symposium, “CVD Technology for VLSI,” was organized by the ECS Japan Chapter, where the invited speaker Dr. Martin Green (AT & T) requested to convene a tungsten workshop in Japan. Moreover, at the 5th Tungsten Workshop (in Albuquerque) held in 1988, Dr. Blewer requested Mr. Takayuki Ohba (Fujitsu), Mr. Nobuyoshi Kobayashi (Hitachi), and others to organize a workshop in Japan. It seems that a similar request was made to Mr. Yuji Okuto (NEC) and Mr. Masahiro Kashiwagi (Toshiba) at a later date. Therefore, Professor Seijiro Furukawa (Tokyo Institute of Technology) was appointed as the Chairman, and preparations for the first tungsten workshop in Japan began.
Dr. Blewer from the United States made a formal written request to Professor Furukawa on September 15, 1988, and it was almost decided that it would be held in Japan the following year. Part 1 in the United States from September 20–21 and Part 2 in Japan from October 19–20 became irregular held simultaneously. This was done for the convenience of those attending both the meetings. Japanese workshop members included Furukawa Seijiro (Chairman, Tokyo Institute of Technology), Yuji Okuto (Vice-Chairman, NEC), Masahiro Kashiwagi (Vice-Chairman, Toshiba), Yoichi Akasaka (Mitsubishi), Yoshio Honma (Hitachi), Hajime Ishikawa (Fujitsu), Iwao Ohdomari (Waseda University), Yasuaki Terui (Matsushita Electric), Kazuo Tsutsui (Tokyo Institute of Technology), and Shintaro Ushio (Oki Electric). The first Japan Committee was held in January, 1989. The Japan–US Joint Committee of April 12, 1989 in Tokyo included Dr. Blewer and Dr. William Harshbarger (Genus) as the participants from the US. The main agreements at that time were as follows:
- The workshops in the US and Japan will be held at intervals of approximately one month to exchange information. In this arrangement, both parties select their invited speakers independently. (The US invited speakers from Japan, and vice-versa.)
- Host committees of both the countries will invite speakers from abroad and provide travel expenses upon request.
- The papers of both workshops will be published together as MRS proceedings (Red Book).
Therefore, in 1989, the US workshop was held at San Mateo on September 20–21, and the first Japanese workshop was held at the Tokyo Institute of Technology Centennial memorial hall on October 19–20. The Japanese workshop consisted of five invited lectures, 23 general lectures, and 131 participants. Although slightly lesser in scale than the US workshop, it was sufficiently large for a first event. Considering the field of lectures, all invited lectures and 13 of the general lectures, were related to tungsten CVD. Other lectures included CVD of Al and Cu or silicide technologies. Assessing the clerical records held of 1989, we found that the plenary session was held with donation supports from several companies.
Since then, tungsten workshops have been held biennially in Japan, in 1991 (Chairman: Ohdomari), 1993 (Chairman: Yasuhiro Horiike (Hiroshima University)), and 1995 (Chairman: Hiroshi Komiyama (University of Tokyo)). In 1991, the conference name was changed to Advanced Metallization for ULSI Applications, which includes not only tungsten but also LSI interconnect technology and materials. Moreover, the name changed slightly for a brief period in between, but since 1998, it has been named the Advanced Metallization Conference which continues to this day. In the US it is named the AMC, but the Japanese side calls it ADMETA, which has been used consistently since the mid-1990s. It seems that it was used in Japan because it clearly indicates what kind of meeting it is. The event is held in September or October, alternating between the AMC and ADMETA held in the US.
On the Japanese side, Chairman Prof. Kazuo Tsubouchi (Tohoku University), who organized the event in 1997, held discussions during the preparatory stage to revitalize this field and disseminate information in Japan. We concluded that it should be held every year to fulfill this purpose. In 1996, due to the short preparation period, it was held mainly for invited talks and tutorials. However, since 1997, it has been composed of invited and general talks (submitted papers) and is held every year. In addition, since around 1996, the discussion on the customer of the conference is being done. Particularly, a one-day tutorial activity that introduces the basics and latest information on interconnect technology to engineers of wide-ranging fields such as equipment manufacturers in a comprehensible manner had been programmed in response to the pointed out of its importance from Dr. Kashiwagi (AMJ) and the proposal of Prof. Yukihiro Shimogaki (The University of Tokyo) that we should aim for independent profitability of conference management in the long term. We still rely heavily on donations from several companies to fund conferences. However, in the tutorial lectures, we asked participants to fill a questionnaire every year and reflect on it next to improve the level of engineers and researchers in this field. Regarding the management of the conference, 1989 (Chairman: Furukawa), 1991 (Chairman: Odomari), 1993 (Chairman: Horiike), 1995 (Chairman: Komiyama), 1996/1997 (Chairman: Tsubouchi) ). In 1998 (Kyoto University, Chairman of the Committee, Masanori Murakami), the secretariat was not set up, so the members of the committee fully worked as volunteer. Furthermore, Prof. Tsukazuo Tsutsui (Assistant Professor, Tokyo Institute of Technology), Prof. Hiroshi Kawarada (Associate Professor, Waseda University), Prof. Shoso Shingubara (Associate Professor, Hiroshima University), Prof. Shimogaki Yukihiro (Associate Professor, University of Tokyo), Prof. Kazuya Masu (Associate Professor, Tohoku University), and Prof. Yasuo Koide (Assistant Professor, Kyoto University) contributed significantly. By the end of 1997 (Chairman: Prof. Masanori Murakami, Kyoto University), we realized that for the continuous and effective organization of the conference, the chairmanship should not depend on an individual. Therefore, we decided to establish a secretariat to enable lead engineers in companies should also serve as chairpersons. From 1998 to 2003, we asked Office Sophiel to serve as the conference secretariat, and from 2004, we requested Realize AT to serve as the conference secretariat. By improving the management system, Dr. Nobuyoshi Kobayashi (Hitachi) and Dr. Takayuki Ohba (Fujitsu Laboratory), who are pioneers in the tungsten CVD technology and are the living members of the plenary session, were also be appointed as chairpersons. Since then, the chairmanship alternates between universities and companies, as it symbolizes an industry–academia–government collaboration. In addition, we created an environment where members of companies can fulfill the responsibility of managing the academic society. Initially, the committee members were mainly companies, and they developed it by including people from related fields of the university. Recent committee members include device manufacturers and equipment-related and material-related companies. However, the participation of young researchers from universities is decreasing. Considering the future and importance of this field, it is necessary to reconsider the efforts of academia.
The ADMETA was held at the 100th Anniversary Hall of Tokyo Institute of Technology in 1989, the International Conference Center of Waseda University in 1991, and the Sanjo Conference Hall of Tokyo University in 1993; however, it has been held since 1993 at the Sanjo Conference Hall of Tokyo University. It is an excellent venue and can accommodate the number of Japanese researcher engineers in this field. Prof. Shimogaki (The University of Tokyo) provides a substantial contribution to the annual event.
Since 2003, the ADMETA Award has been awarded to the best papers, and since 2004, the Technical Achievement Award has been established for several highly technical papers. The award inspires researchers to present at ADMETA, and further development can be expected in the future. In addition, considering that the award evaluated not only the contemporary high level of technology but also its impact on the future, it can be said that the insights of the selection side, that is, the ADMETA Committee, are questioned.
In the last few years, ADMETA has received about 50 papers in general lectures and around 10 invited lectures. It was held on the one-day of the tutorial and two-days of conference, and there were about 100 tutorial participants and 200 participants in the conference. In contrast, at the AMC held in the US, the total number of papers was around 100, and the number of participants was approximately 200–250.
The policy of convening simultaneous conferences in Japan and the US, shifting the schedule by approximately one month has been observed since 1989, and both papers will continue to be published as MRS Proceedings (Red Book) in one volume. Today, Red Book is popular as the best-selling series for its several published MRS Proceedings. It has gained a reputation for providing cutting-edge information on interconnect technology in a single book.
For reference, the inside cover and preface of MRS Proceedings of the tungsten workshop Vol. 1 and Vol. 5 (the first Japan and US Joint special issue) are indicated after this text. It conveys the founding atmosphere of the workshop at that time. In addition, we will post a list of Chairs for AMC and ADMETA. It has become customary for each person to take charge of the ADMETA once, except for the Chairman Prof. Tsubouchi. In contrast, the Chairman of the AMC, Dr. Robert S. Blewer, who can be said to be the founder, has been in charge consecutively for three years, and Dr. Yoshi Diamand and Dr. Andrew J. McKerrow have been in charge multiple times since its inception. There is also a difference in social background, but the management format will be significantly helpful in the future.
From 1995, ADMETA was held every year, it has now established itself as a domestically held international conference related to interconnect technology, and is recognized both at home and abroad. It has been approved by the Silicon Technology Subcommittee of the Society of Applied Physics since 2000, and co-sponsored and approved by the Surface Technology Association, Institute of Electrical Engineers of Japan, Precision Engineering Society, Institute of Electronics, Information and Communication Engineers, Japan Institute of Metals, IEEE Japan Council, Vacuum Society of Japan, and Surface Science Society of Japan.
In recent years, due to structural changes in the LSI industry, there have been active movements to integrate device manufacturers and merge devices and process development businesses. The R&D related to process technology tends to decrease from the device makers. The mainstream of R&D is shifting to consortia, such as SELETE, equipment makers, and material makers. In the overall flow of interconnect technology, such changes in industrial structure and development of Cu/Low-k technology are advancing, and there is concern that R&D will stagnate soon. When conventional technologies will evolve, the opportunities for new and different technologies will emerge. Three-dimensional packaging and nano tube interconnect are becoming important, therefore, associated new technologies deployed for wiring, would be desirable to further propose new materials, processes, and concepts. ADMETA is expected to continue to play an even more critical role as a forum for lively discussions between researchers in the technological field approaching maturity and researchers in the emerging technological field. We want to pay attention to the development of the LSI interconnect technology in the next 10–20 years, along with the future development of ADMETA.
Finally, ADMETA has received donations from several companies since its inception in 1989. They have supported the progress of Japanese technology in this field and the dissemination of information. We hope that ADMETA will continue to lead the world in this field and that related industrial fields will develop further, and we would like to express our deep gratitude for your continued support.
Note: Names and affiliations in the text are those at that time. Acknowledgments: We would like to express our sincere gratitude to Professor Kazuya Masu of Tokyo Institute of Technology for providing us with valuable insights and advice in compiling this article and Associate Professor Kazuo Tsutsui of Tokyo Institute of Technology for providing us with valuable materials.
Since the beginning of the microelectronics era, integrated circuits (ICs) have been fabricated for silicon, oxygen and aluminum in elemental or compound form. Now after more than 30 years of a new class of refractory materials is being added to basic elements that have been sufficient for so long, in response to changing materials requirements dictated by smaller IC feature size, higher current densities and the desire for better electrical performance. Design requirements have narrowed the choice of materials to those which exhibit low contact resistance to silicon, high resistance to the effects of electromigration at contacts or steps, and to materials which can be deposited at temperatures low enough to preserve ever shallower junctions.|
To address these needs, tungsten and other refractory metals are being seriously considered for use in advanced ICs. In particular, low pressure chemical vapor deposited (LPCVD) selective tungsten has been shown to meet a variety of requirements on VLSI and ULSI chips such as a diffusion barrier etch barrier, via fill, low resistance shunt of source/drain regions and on gates in pure or silicide form. Tungsten is also being applied as an IC fabrication aid, such as self aligning scratch—resistant pads for in—Process testing, stencils for etch selectivity enhancement and masks for X-ray lithography, low reflectivity coatings, etc. and even for novel passive microdevices such as squids, bridge wires, etc.
In addition to its favorable physical properties, tungsten is of particular interest because it can be deposited selectively on silicon, metals or silicides, so that it is truly self aligning. Tungsten can also serve a volume filling function thus enhancing planarity, a high priority in multilevel chip designs. Because it can be deposited without additional masks, process complexity is reduced with a concomitant cost savings. Increased use of in process testing is expected to enhance yields. As IC technology is driven to smaller feature size and multiple interconnect levels, the selective deposition capability of this CVD process will become ever more important.
Another respect in which this technology is unique concerns the timing and pace of selective LPCVD tungsten development. Seldom does the community of integrated engineers have an opportunity to jump sufficiently far ahead of current practice with a new material or fabrication technique that basic physical understanding preceeds corporate commitment to product development. More often it is the case that industry—wide progress is actually retarded because new discoveries remain closely guarded corporate secrets until the company involved markets new products which make use of the discovery. Because of rapid progress in LPCVD tungsten technology in the last 18 months, the development of LPCVD selective tungsten may just be an exception to the rule. Tungsten technology has to a large extent leap-froged silicide development; much of what needs to be known in applying tungsten techno— logy to bypass current IC design and fabrication constraints has come to light as a result of two workshops in this area, well before major corporate commitment has inhibited free information exchange.
The two workshops whose proceedings comprise this volume, focused on deposition techniques and uses of tungsten and other refractory metals for VLSI applications. These conferences were an outgrowth of several private, "off—the—record" meetings among four or five scientists who were active in LPCVD tungsten research. In this setting, information on results and ideas flowed naturally. In August, 1984, a decision was made by a group of eight who had published in the area of LPCVD tungsten in the previous two years to hold an informal two—day workshop on November 12—13, 1984 at Sandia National Laboratories to exchange results, to gauge interest in this emerging technology and to identify others who were beginning work in this area. Despite the short advance notice and little more than word-of-mouth advertising, 125 participants responded from the USA and seven foreign countries. To enhance open and frank discussions, no proceedings were planned, but at the conclusion of the workshop a strong vote was registered by the conferees to document the information presented in some form and to repeat the Work shop the following year.
A second (enlarged) workshop was thus held in Albuquerque October 7—9 1985 with the advance intention to publish the proceedings, together with abstracts and visual materials from the first workshop. The result is this two—part volume which contains more than 75% of what has been published in the last five years on LPCVT) tungsten, in the opinion of the workshop organizers. It should thus serve as a comprehensive guide for those new to the field and as a reference book for experienced workers. This volume represents the first occasion on which the Materials Research Society has published the proceedings of a conference not organized under its auspices. MRS has expressed the opinion that refractory metals development for integrated circuit applications represents an important emerging technology and, as such, has undertaken to publish not only this but future proceedings of this conference. Future workshops on tungsten and other refractory metals for VLSI (and ULSI) applications will be held in the fall of each year, a time which is adequately spaced with respect to the Silicides Work- shop, normally held in May and the VLSI Multilevel Interconnection Conference, normally held in June each year. Information on the date and location of upcoming workshops can be obtained from XXXXXX, University EXtension, University of California, Berkeley, (415) 642—4151, who is in charge of workshop administration.
Robert S. Blewer
This volume, which contains the papers presented at the Sixth Workshop on Tungsten and Other Advanced Metals for VLSI/USLI Applications, represents a significant milestone in the history of the workshop. This is the first time that the workshop was devided into two parts, with the first one held in San Mateo, California, USA, and the second one held in Tokyo, Japan a month later. Although separate committees were set up to administer each portion of the workshop, there were constant communication and interaction between the two committees to ensure a continuous, cohesive workshop. A few papers were invited to be presented at both parts of the workshop to promote the interchange of technical information and concepts. Each part of the workshop was heavily attended, with a total of over 300 participants. The more than 25 papers presented at each portion of the workshop were of excellent quality and represented the state-of-the-art in the field. This indicates that the application of CVD metals, tungsten in particular, has received global attention as a vital technology for VLSI and ULSI; and that the workshop has served as an efficient forum for detailed documentation and rapid dissemination of knowledge. Although only a few fortunate individuals were able to attend both parts of the workshop, the publication of this proceedings will serve a similar purpose for those who could not. It has been demonstrated that with careful planning and coordination, a workshop can be divided and held in various sites so that more people can participate and benefit. This may serve as an example for any conference in which global participation is desirable.|
This proceedings includes the keynote presentation which reveals why global participation and mutual understanding are essential to fostering the continuing and rapid progress in this field. The remaining papers summarize the latest results in the understanding of surface reactions; the modeling of reactor and deposition kinetics; the development of blanket and selective tungsten deposition processes; the characterization of tungsten films; and the rapid development in other CVD metals such as copper and aluminum.
S. Simon Wong
|1984||-||Tungsten and Other Refractory Metals for VLSI Applications; Robert S. Blewer|
|1985||-||Tungsten and Other Refractory Metals for VLSI Applications; Robert S. Blewer|
|1986||-||Tungsten and Other Refractory Metals for VLSI Applications; Robert S. Blewer|
|1987||-||Tungsten and Other Refractory Metals for VLSI Applications; Eliot K. Broadbent|
|1988||(Held a CVD technology symposium for Ultra-LSI) (ECS Japan branch, March)||Tungsten and Other Refractory Metals for VLSI Applications; Victor A. Wells|
|1989||Tungsten and Other Advanced Metals for VLSI/ULSI Applications; Seijiro Furukawa||Tungsten and Other Advanced Metals for VLSI/ULSI Applications; S. Simon Wang|
|1990||-||Tungsten and Other Advanced Metals for ULSI Applications 1990; Gregory Smith, Roc. Blumential|
|1991||Advanced Metallization for ULSI Applications; Iwao Ohdomari||Advanced Metallization for ULSI Applications; Virendra V.S. Rana, Rajiv V. Joshi|
|1992||-||Advanced Metallization for ULSI Applications 1992; Timothy S. Ca1e, Fabio S Pinchovsky|
|1993||Advanced Metallization for ULSI Applications 1993,Yasuhiro Horiike||Advanced Metallization for ULSI Applications 1993; David P. Fabreau, Yosi Shacham-Diamand|
|1994||-||Advanced Metallization for ULSI Applications 1994; Roc. Blumential, Guido Jansenn|
|1995||Advanced Metallization and Interconnect Systems for ULSI Applications 1995; Hiroshi Komiyama||Advanced Metallization and Interconnect Systems for ULSI Applications 1995; Russel C. Elwanger, Shi-Qing Wang|
|1996||Advanced Metallization and Interconnect Systems for ULSI Applications 1996; Kazuo Tsubouchi||Advanced Metallization and Interconnect Systems for ULSI Applications 1996; Robert Havemann, John Sanchez|
|1997||Advanced Metallization and Interconnect Systems for ULSI Applications 1997; Kazuo Tsubouchi||Advanced Metallization and Interconnect Systems for ULSI Applications 1997; Robin Cheung, Jeffrey Klein|
|1998||Advanced Metallization Conference in 1998; Masanori Murakami||Advanced Metallization Conference in 1998; Gurtaj Sandhu, Heinrich Koerner|
|1999||Advanced Metallization Conference 1999; Nobuyoshi Kobayashi||Advanced Metallization Conference 1999; Mihal E. Gross, Thomas Gessner|
|2000||Advanced Metallization Conference 2000; Yukio Yasuda||Advanced Metallization Conference 2000; Dan Edelstein, Girish Dixit|
|2001||Advanced Metallization Conference 2001; Takayuki Ohba||Advanced Metallization Conference 2001; Andrew J. McKerrow, Yosi Shacham Diamand|
|2002||Advanced Metallization Conference 2002; Shigeaki Zaima||Advanced Metallization Conference 2002; Bradley M. Melnick, Timothy S. Cale|
|2003||Advanced Metallization Conference 2003; Tomohiro Ohta||Advanced Metallization Conference 2003; Gary W. Ray , Tom Smy|
|2004||Advanced Metallization Conference 2004; Kazuya Masu||Advanced Metallization Conference 2004; Darrel Erb, Peter Ramm|
|2005||Advanced Metallization Conference 2005; Manabu Tsujimura||Advanced Metallization Conference 2005; Sywert H.Brongersma, Thomas C. Taylor|
|2006||Advanced Metallization Conference 2006; Akihiko Osaki||Advanced Metallization Conference 2006; Stephen W. Russel, Michael E. Mills|
|2007||Advanced Metallization Conference 2007; Shoso Shingubara||Advanced Metallization Conference 2007; Andrew J. McKerrow, Yosi Shacham Diamand|
|2008||Advanced Metallization Conference 2008; Takashi Yoda|
|2009||Advanced Metallization Conference 2009; Yukihiro Shimogaki|
|2010||Advanced Metallization Conference 2010; Seiichi Kondo|
|2011||Advanced Metallization Conference 2011; Kazuyoshi Ueno|
|2012||Advanced Metallization Conference 2012; Hisao Kawasaki|
|2013||Advanced Metallization Conference 2013; Junichi Koike|
|2014||Advanced Metallization Conference 2014; Eiichi Kondo|
|2015||Advanced Metallization Conference 2015; Young-Chang Joo|
|2016||Advanced Metallization Conference 2016; Takenao Nemoto|
|2017||Advanced Metallization Conference 2017; Osamu Nakatsuka|
|2018||Advanced Metallization Conference 2018; Tian-chun Ye and Chao Zhao|
|2019||Advanced Metallization Conference 2019; Shinji Yokogawa|
|2020||Advanced Metallization Conference 2020; Asian Session, Special Symposium; Kazuyoshi Maekawa|
|2021||Advanced Metallization Conference 2021 30th Anniversary, Asian Session; Kazyoshi Maekawa;|