Paper VT-MoA5
Low Outgassing, Low Permeability Elastomeric Seals for High Purity PVD Processing

Monday, October 20, 2008, 3:20 pm, Room 205

New processes associated with semiconductor manufacturing and in related industries require very clean, high vacuums. Systems utilized for such processes employ a multitude of seals with emphasis in elastomeric seals for transfer handling of substrates. The process environments require such seals to have very low outgassing and low permeability to the atmosphere as well as the gases used in processing. Recent developments of new elastomer seals employing perfluoroelastomers provide the characteristics suitable for these applications. Various material and fabrication technologies are described as used for fabricating seals for high vacuum, ultra high purity environments. This paper will review the new technologies and their effect on the properties of seal materials, the seals themselves and associated equipment performance. Examples of such optimization of seal technology will show the achieved characteristics for seals capable of sustaining vacuums of 10^-9 Torr and at temperatures to 280 ^oC. The outgassing characteristics of a variety of seals will be shown for H₂O, HF, H and O₂, all potential contaminating gases during depositions of films for semiconductor and photovoltaic thin films. The low level of outgassing attainable by the more recently developed materials and the technology associated with such properties will be described. Through the use of a “tighter” bonding perfluoro molecular structure, combined with molecular based fillers, a molecular structure has been developed which greatly reduces permeability. Through a uniquely developed molding process, key of which is the cooling cycle, a tighter molecular structure is achieved. These new materials provide both the characteristics required for high performance PVD deposition equipment as well as addressing the highly corrosive and aggressive environments found in semiconductor etching and CVD equipment. The progress made in increasing the longevity of seals is such applications is described as this is becoming very critical in future technology nodes manufacturing. Data for use with NF₃, CF₄ and O₂ plasmas is presented to better understand the deterioration of the elastomers and associated mechanisms. The impact of temperature is also described showing that at chamber temperatures approaching 300 ^oC, such new seal materials still function suitably. Descriptions of these extended applications will be given along with the resultant enhanced performance.