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Product Briefing Outline: Matheson Tri-Gas Electronics has introduced its patented ‘PICO-TRAP’ Ultra-Purification System for removing volatile metal impurities and moisture from critical process gases used by semiconductor manufacturers. The PICO-TRAP System combines the principles of chemisorption and physisorption to achieve higher levels of process gas purity than by conventional purification technologies, according to the company. 

Problem: One of the key considerations for the introduction of new processes and technologies for 45nm-and-below technology nodes is the need to lower the process temperature of the substrate so that further deposition can be achieved without damaging the sensitive layers already on the wafers. However, by running process conditions at lower temperatures, some of these steps are experiencing higher levels of sensitivity to errant moisture or other volatile impurities than ever before. Additionally, existing semiconductor manufacturing lines are pushing the limits of their production tools for higher throughputs, increased yields and lower defect densities. One way to accomplish this is to reduce the impurity levels of the purge and process gases so that production cycles may reduce temperature ramp and purging requirements.

Solution: The PICO-TRAP System removes moisture down to low detectable limits, such as less than 20 pbb in hydrogen chloride (HCl).  Existing purifiers have been shown to reduce moisture only down to 100 to 400 ppb, according to the company. This extreme level of purification is attained even with high impurity challenges of 25 ppm moisture or more when the source runs to a cylinder dry condition. The system also removes volatile metals including iron (Fe), molybdenum (Mo), chromium (Cr), titanium (Ti), nickel (Ni) and manganese (Mn), which inherently affect yield and defect densities in key fabrication processes. In addition, non-conventional impurities such as methane (CH₄), silicon tetrafluoride (SiF₄) and hydrogen fluoride (HF) can be significantly reduced in highly reactive process gases by the PICO-TRAP System. In recent studies by Matheson Tri-Gas Electronics researchers, the PICO-TRAP System demonstrated that silicon-epitaxial operations at both high and low temperatures were enhanced by purifying hydrogen chloride etchant gas. The improved process results were achieved by decreasing moisture content to less than 20 ppb, showing a 10X improvement over standard purification methods, and by reducing volatile metal impurities to nearly undetectable limits.

Applications: Volatile metal impurity reduction to sub ppb levels and moisture to less than 20 ppb.

Platform: PICO-TRAP works with a combination of using both physical and chemical methods with the Matheson Tri-Gas ‘NANOCHEM’ purification technology, along with a sub-cooling chamber of specialized purification material. The system uses PLC logic control with fully in-situ regeneration capability and is flexible enough to operate with a wide variety of specialty gases and tool applications.

Availability: July 2008 onwards.