SIA Roadmap Highlights Contamination Control
By John Haystead
San Jose, CA–The Semiconductor Industry Association`s (SIA`s) “1994 National Technology Roadmap For Semiconductors” includes a significant amount of discussion and a number of recommendations relative to Contamination-Free Manufacturing–one of six “crosscutting technologies” specifically addressed by each of the eight Technical Working Groups contributing to the report.
A key observation made in the report, which projects the needs of the semiconductor industry over a 15 year timeframe, was that “contamination sensors for particles and moisture are available and should be implemented for statistical process control.” While concluding that particle, moisture, metal, and organic contamination sensors are necessary for real-time monitoring and control within fluid lines as well as wet and dry process equipment, the report emphasizes that “the most critical need is for process equipment manufacturers to integrate these sensors into the hardware and software of the equipment.”
Low-cost gas analysis sensors such as residual gas analysis, optical emission spectroscopy, and intracavity laser spectroscopy were specifically identified as strong candidates for equipment integration, while metal and total oxidizable-carbon contamination measurement in liquids was also considered essential. Sensors capable of monitoring wafer contamination during processing is a recurring theme of the report.
The SIA report also identifies point-of-use (POU) purification “as a key driver for fluid purity” and states that “fluid purity requirements should be based on device impact.”
Specialty gases and chemicals were particularly targeted for improvement in the study which says, “specialty-gas purity measurement requires improved condensation nucleus counter (CNC) technology, and fluid-purity improvement efforts need to be focused on specialty gases and POU filtration/purification.”
According to the roadmap, “in general, current fluid purity levels appear to be adequate for meeting 0.35-µm technology requirements,” with additional POU purifiers and filters being used to meet the more stringent requirements, but smaller feature sizes will require purity improvements in specialty gases and liquid chemicals, including deionized water. “By the year 2000,” says the report, levels of “inline total organic carbon, nonvolatile residue, silica and metals below 0.01 ppb will be needed for deionized water.”
Among the potential approaches to achieving these purity levels, the report suggests source purification, POU purifiers, filters, recycling/reprocessing, and POU chemical generation.
The report further recommends “fundamental studies of the impact of contaminants on device performance” and calls for experimental validation of model-derived purity specifications as well as the development of cost-of-ownership models for higher purity fluids. While the report indicates that no major changes are required for bulk gases such as nitrogen and argon, “sensor technology for corrosive fluid monitoring is needed to better understand purity levels at the point of use.”
Some 300 leading technologists from industry, government and academia contributed to SIA`s Technology Roadmap. Copies of the complete report are available (free of charge) by calling the SIA Office at (408) 246-2711. n