Contamination Control Projects Continue at NCAICM
By Lisa A. Coleman
Albuquerque, NM–Three projects are now underway at the National Center for Advanced Inform ation Components Manufacturing (NCAICM), a collaboration between the Advanced Research Projects Agency (ARPA) and the Department of Energy, that may have significant results for controlling contamination in the microelectronics industry.
Last October, the Chemical Vapor Cleaning for Advanced Contamination-Free Manufacturing project headed up by Air Products and Chemicals, Inc. (Allentown, PA) began. It will evaluate the feasibility of removing metal contamination from semiconductor surfaces using dry processing. Air Products will use the reverse of chemical vapor deposition to remove metal contamination–copper, iron and sodium–from a semiconductor surface without damaging the surface. “It`s a potentially enabling technology,” says David Bohling, research associate and R&D manager for Air Products and Chemicals. “This may be one of the only ways to remove metals without damaging the surface.”
Air Products has been researching dry processing for the last five years. The NCAICM project will work on expanding Air Products existing work by at least an order of magnitude. “There`s a high technical risk, but we`re confident we can reach it,” says Bohling. Dry processing has the potential to save money in cleanroom costs because the cleaning method needs very little space compared to wet benches.
Another NCAICM project, which has been underway since 1992, is the In-situ Particle Monitoring in Microelectronic Manufacturing Processes. The project uses an optical system for in situ measurements in microelectronic manufacturing. Insitec Measurement Systems (San Ramon, CA) developed a prototype high volume counter (HIVOL) optical system for in situ measurements. Insitec developed a breadboard prototype for in situ measurements down to 0.2 micrometers. Currently, Sandia National Laboratories (Albuquerque, NM) and Insitec are modifying a plasma etching tool so that the HIVOL design can be interfaced to it. “It`s a matter of doing it within the constraints and environment of a plasma etcher. That`s the big unknown. Nobody`s every really done it directly while the equipment is going,” says Don Holve, president of Insitec. The company has also developed a preliminary signal processor and software to interface with HIVOL.
Making measurements continuously and on-line are the key parts of the project, says Holve. On-line, in situ sensors can enhance chip yields through improved local process control at the site of contamination. In order to improve the yield in manufacturing microelectronics, an instrument is needed that can perform in situ particle measurements in vacuum processing chambers; submicron particle detection; and maximize particle count rates at conditions of low-particle concentration.
Rounding out the NCAICM projects are spin-off projects from Sandia`s Contamination Free Manufacturing Center. Researchers are developing high-sensitivity sensors for detecting contamination and measuring defects during the manufacturing process.
The sensor development includes a surface acoustic-wave chemically selective coating on an IC. A chemically sensitive film is placed on the IC and then as moisture forms, a sample gas is passed over the film. The moisture is adsorbed by the film and changes the acoustic velocity of the wave.
Although the technology is not new, researchers at Sandia are working to develop new films for detection, says Kent Pfeifer, a member of the Sandia technical staff. Pfeifer is trying to develop a sensor that will work in hydrochloric acid. “The intent of the project was to succeed enough so that some company would take over the manufacturing and then sell the chips to the semiconductor industry,” says Pfeifer. The project is slated for completion by October 1995. n