Wafer Fabrication Equipment Research Articles

Perfluorocompounds emission reduction by the semiconductor industry

The semiconductor industry uses a number of gases classified as perfluorocompounds (PFCs) in both silicon and dielectric layer etching and chamber cleaning in wafer fabrication equipment. The use of PFC gases in these processes is crucial to the production of semiconductor devices, as there are no effective substitutes that can be utilized. Although PFC emissions caused by the semiconductor industry are a tiny fraction of all industry greenhouse gases emissions, the world's semiconductor manufacturers, assembled in the World Semiconductor Council (WSC) and its affiliated associations, have officially agreed to voluntarily reduce atmospheric emissions of PFCs to 10% below baseline levels in 2010. The WSC has established a reporting program to track PFC emissions by the present five semiconductor manufacturing associations (USA, Europe, Japan, Taiwan, Korea). Data released by the WSC today show that the 2008 PFC emissions in most regions are already below the target set for 2010. This cooperative effort by the members of the WSC to reduce PFC emissions is an excellent example of what can be accomplished by collaboration. Because the PFC emission reduction program is considered to be pre-competitive, members freely share information on techniques and strategies. One of the key success factors has also been the strong involvement of equipment and gas suppliers to the semiconductor industry. Key measures that have contributed to substantially reduce PFC emissions are, among others, installation of dedicated post process tool PFC abatement, and application of NF3 gas in combination with so-called remote plasma in chamber cleans. The latter affords a highly efficient process alternative for the semiconductor industry with minimal PFC emission footprint, since the NF3 is utilized with better than 98% conversion efficiency. A gradual trend is visible, i.e. more advanced tools and facilities with relatively low emissions are supplanting relatively old tools and facilities with relatively high emission profiles. Presently, the global semiconductor industry is considering whether and how PFC emissions can be further reduced post-2010. A new global agreement should include other relevant regions with substantial semiconductor production, such as China and Singapore. Such discussions have already commenced. One of the key elements in a new agreement is harmonization of regional reporting. Moreover, it should be emphasized that semiconductor manufacture is no longer the sole or even the largest industry that makes use of PFCs. In this respect, the production of Liquid Crystal Displays (LCDs) and the manufacture of photovoltaic cells are likely to become major players.

Templateless prototyping of polydimethylsiloxane microfluidic structures using a pulsed CO2 laser

We present a novel process (through cutting and pattern transfer processes) for rapidly prototyping polydimethylsiloxane (PDMS) microfluidic structures without a replication template using a CO2 laser. The process typically takes less than 30 min to make a PDMS microfluidic chip from idea to device. In addition to time saving, the process also drastically cuts down equipment and operating costs by eliminating the use of masks, templates, wafer fabrication equipment and consumables needed in the template-making process. We further demonstrate the capability of the process in the rapid prototyping of a variety of microstructures from a 2 µm thin layer up to a 3.6 mm high structure on a single PDMS layer with accurate thickness control as well as smooth top and bottom surfaces. Various process characteristics and challenges for the PDMS laser prototyping process are addressed in this note.