Japanese authority reveals secrets

— John Haystead

Ultraclean Surface Processing of Silicon Wafers — Secrets of VLSI Manufacturing

By Takeshi Hattori (Ed.).

Illustrated. 616 pp. Berlin Heidelberg New York:

Springer-Verlag. $189.00.

Dr. Takeshi Hattori, ULSI R&D Laboratories, Sony Corp. Semiconductor Co. has long been recognized in both the contamination control and semiconductor manufacturing communities for his strong, sometimes controversial, views on VLSI manufacturing techniques. In particular, Dr. Hattori is an unequivocal proponent of focusing contamination-control practices and technology on their specific impact at the surface of the silicon wafer as opposed to strictly relying on the cleanliness levels of the overall semiconductor manufacturing environment. His book Ultraclean Surface Processing of Silicon Wafers — Secrets of VLSI Manufacturing describes how contamination control technology and practices, specifically aimed at process equipment and metrology, will be essential to the production of reliable, next-generation nanoscale devices.

This book, which targets engineers, physicists and technicians involved in semiconductor-device manufacturing, is a revised, updated and expanded translation of a Japanese-language edition published in 1995 by Realize Inc. under the title Silicon Wafer Hyomen no Clean-ka Gijutsu. As Hattori notes, until very recently, Japanese companies have treated their contamination-control practices and overall manufacturing technology as highly proprietary, tightly held secrets, a practice that has restricted the flow of scientific information and hindered an efficient, systematic approach to dealing with next-generation contamination concerns. In addition to an introductory overview by Hattori, the book includes over 40 contributions from Japan`s premier researchers and implementers of advanced semiconductor manufacturing technology.

Today`s VLSI processes must address not only particulate contamination but the heavy metal impurities introduced by the process equipment itself such as ion implantation, dry etching, resist ashing, sputtering, plasma CVD, etc. Other contaminants such as&#165and B dopants, HF vapor introduced to the cleanroom from improper exhaust and airflow systems, and volatile organic materials emitted from cleanroom construction materials and wafer-handling tools must now be considered substantial yield-limiting concerns. For example, although many readers may recognize at an intellectual level the problems associated with the concentration of low-density chemical contamination, Dr. Hattori`s book eloquently raises these concerns to the forefront, pointing out that these problems must be addressed with real-world solutions on the manufacturing floor today, not merely relegated to esoteric academic discussion. Says Hattori, “the adaptation of the semiconductor production environment has been remarkably slow. In order to achieve this the following is crucial: automation and standardization of manufacturing and transport equipment, and the achievement of particle-free (or self-cleaning) and highly reliable equipment — the fact that the equipment must be altered so often becomes an impediment to the realization of the method.”

With a total of eight sections and 46 chapters, the book does a good job of addressing most aspects of the vast subject of ultraclean technology for VLSI manufacturing with specific, hands-on examples including demonstrated problems and proposed and tested solutions. In particular, the book stresses the importance of developing test and measurement instrumentation and procedures commensurate with the levels and types of contamination of increasing concern to the industry. “To this end, the urgent task at hand is first to develop and enact high-sensitivity, simple contamination measurement/evaluation technologies in step with the progress of VLSI miniaturization, because, after all, the basis of contamination control is grasping accurate measurements of the contaminants. In comparison with progress in VLSI processing technology, progress in measurement technology has been remarkably slow.”