IMEC hones focus on processing technologies
By Peggy Trautman
Leuven, Belgium — IMEC, a large independent research center in the worldwide field of microelectronics, is positioning itself to play a larger role in developing processing tech nologies. IMEC will focus on better integrating single steps in the manufacturing chain to create more simplified overall process technologies for the next generation of chips, optoelectronic components, microsystems, solar cells and sensors.
Special attention will be paid to further refining IMEC`s ultraclean processing. In the past IMEC has devoted its effort to developing high-performance techniques that are cost effective and environmentally friendly. “Five to 10 years ago people said, cleaning is no science it`s just something you have to do,” recalls Roger Van Overstraeten, IMEC president. “Now we see that cleaning is becoming more important because the complexity of the whole process is rapidly increasing. You can keep up the yield if you simplify the process and focus on the cleaning aspect.”
“Cleaning has been and always will be a vital step in the semiconductor manufacturing process,” says John Goodman, president of the IEST and vice president of engineering at Fluroware Inc. (Chaska, MN). “IMEC has made significant contributions to the understanding of wafer cleaning at the fundamental and applied level.”
For Marc Heyns, IMEC group leader of ultraclean processing technology and environmental safety and health, cleaning techniques are an area where IMEC has achieved the best results. “We try to bridge the gap between the world of fundamental research and things that are happening on the production floor,” Heyns says. “I think that is our advantage (over other centers) because we can make a link between these two worlds that don`t otherwise communicate so well.
“The way that we try to link the research and the activities on the production floor is simply by putting more science into the `black magic` that cleaning used to be while at the same time doing research on problems that are relevant for a production environment and taking production concerns (such as cost, process robustness, throughput, machine footprint, chemical and DI-water consumption) into account,” Heyns explains. “Until a few years ago, the understanding in the cleaning concepts used in production was relatively limited. When you asked people why they did certain things, the main answer was `because we have always done it like that.` By bringing more insight into what really was going on, large improvements could be made. IMEC has a pretty unique position in this because we do both fundamental research and the application in our own prototyping line. Therefore, we can close the gap that often exists between these two worlds.”
Among the group`s milestones is its IMEC Clean process. To date, the IMEC clean process has been implemented in an automatic wet bench (Steag MicroTech) in the IMEC pilot line. Its performance was compared to an optimized RCA clean and the results were always at least as good, and in most cases even better, but at lower cost and lower chemical and DI-water consumption, Heyns notes. Excellent results were also obtained for the metal contamination levels after cleaning, the removal of all sorts of particles and the density of defects of thermal oxides grown up after the cleaning step.
In addition, IMEC solved the problem of alkalinity in the cleaning bath that results when photoresist is removed from metallized wafers. It developed a new rinsing method in which an inorganic acid was added to the rinsing water to monitor the pH and prevent corrosion of metal layers.
In addition to their work on improved cleaning methods, IMEC has also studied “how clean is clean enough?” Goodman observes. “The IMEC work on required levels of cleanliness for a given process or contaminant (rather than just on the lowest level that can be achieved irrespective of cost) is perhaps even more important than their research on cleaning methods alone.”
IMEC has also tackled the problem of chemical consumption in the cleaning process. “We have been working on processes to get rid of the typical sulfuric acid step that is used for cleaning. We have developed a process we believe can fully replace the sulfuric acid steps that people use at the present time,” Heyns explains. “It is important because it allows us to boost production and cut costs in a way that uses the environment as a boundary to develop new processes.” The announcement detailing this breakthrough was scheduled for last month.
Such accomplishments will pave the way for IMEC to strengthen its ties with industry, Van Overstraeten notes. In 1997, IMEC cooperated with almost 5,000 companies and research institutes worldwide, a 15-percent increase over 1996. The total income from contract research jumped almost 21 percent from $31 million in 1996 to $37 million in 1997. This growth will continue in the future, Van Overstraeten stresses, particularly since the center is more determined to function as a business and bring its solutions to industry.
The Belgium-based center, which was founded in 1984 in an effort by the Flanders government to jump-start the microelectronics industry in the region, has begun to function more like a business and plans to take a more proactive role in microelectronics R&D, he notes.
One step in this new direction has been the formation of an IT-oriented capital fund. Launched by IMEC, the IT-Partners fund has helped four companies start operations. The most recent is Custom Silicon Configuration Services, a new European semiconductor assembly foundry that will be active in advanced packaging technologies. The company, which is located close to IMEC, will subcontract manufacturing with a high level of service.
IMEC also recently joined a local university in founding AnSem, a company that commercializes the know-how available in the field of analog integrated circuit design. AnSem offers design service, realization and innovation of analog and mixed-signal integrated circuits.
Among IMEC`s R&D facilities are a VSLI design methodology laboratory, a silicon pilot line for submicron CMOS processing, a pilot line for multi-chip modules and a microsystems laboratory.
Peggy Trautman is the European correspondent for CleanRooms International.