AVS 46th International Symposium
    Manufacturing Science and Technology Group Monday Sessions
       Session MS-MoA

Paper MS-MoA7
Investigating Molecular Contamination in Cleanrooms

Monday, October 25, 1999, 4:00 pm, Room 611

Session: Ultra-Clean Society and Contamination Free Manufacturing
Presenter: P.H. Schnabel, Charles Evans & Associates
Authors: P.H. Schnabel, Charles Evans & Associates
G. Goodman, Charles Evans & Associates
D. Nehrkorn, Surface Science Laboratories
M. Kendall, Surface Science Laboratories
G. Strossman, Charles Evans & Associates
P. Lindley, Charles Evans & Associates
Correspondent: Click to Email
As the line widths of microelectronic devices approach 0.1 micron, the presence of airborne molecular contamination (AMC) in fabs and cleanrooms has become a major concern for the semiconductor industry. In order to achieve low defect rates in these next generation devices the technical ability to identify, isolate and eliminate AMC is a substantial challenge. AMC can potentially result from every material within a cleanroom or a fab but the main sources for AMC are process chemicals, construction materials and the local environment. AMC defects can cause changes in the wafer's electrical properties, uncontrolled boron or phosphorous doping, etch rate shifts, threshold voltage shifts, wafer and stepper optics hazing and high contact resistance. In this study we demonstrate that TOF-SIMS can be utilized for identifying different types of condensable airborne contaminants and for monitoring those contaminants in cleanrooms. For this purpose witness wafers were placed in a newly constructed class 10 cleanroom and analyzed periodically over a time of 6 months. In order to identify potential sources of AMC the ougassing of individual materials that are typically present in cleanrooms was studied by TOF-SIMS, GCMS and FTIR. The materials under investigation include cleanroom construction materials (e.g. floor tiles, filters, sealant etc.), cleanroom furniture, cleanroom garments and cleanroom utensils. In these experiments each of the materials 'delivers' a fingerprint which can be used to identify potential sources of cleanroom contamination. The transfer of contaminants onto silicon wafers that are brought in contact with these materials was studied as well. The long term objective of this part of our studies is to generate an extensive database which allows us to link the observed contaminants on wafers with potential sources within the cleanroom environment. Both, transfer through the gas phase and by contact will be evaluated.