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Proceedings Paper

Application of SMIF isolation to lithography processes for contamination control
Author(s): Sheng-Bai Zhu
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Paper Abstract

Contamination control is particularly important in lithography processes because pattern defects are converted to wafers after each exposure. Contamination, by definition, is undesired matter or energy, which causes product defects or process instabilities, and, consequently, reduces yield and reliability. In lithography processes, particles, condensable hydrocarbosn, base molecules, moisture, and static electricity are examples of contaminants. Particles are inert minute objects, which interfere with the proper formation of circuit features. Condensable hydrocarbosn may cause optics hazing which reduces image homogeneity and energy transmission. Some Chemically Amplified Resists (CAR) are susceptible to molecular base contamination, resulting in image degradation such as T-topping. Moisture can affect the characteristics of photoresist, destabilizing photo-exposure and development processes. In combination with water, amine containing photoresist strippers can form hydroxyl ions that can attack aluminum and aluminum-copper alloys. Charged surfaces can tract and hold contaminants of opposite polarity. In case the electrical field exceeds the dielectric strength, ESD event occurs, often accompanied with damage of reticles, masks, or wafer circuits. With SMIF isolation technologies, yield loss due to defects and/or instabilities is minimized. Reticles, masks, and wafers are isolated form contamination sources through hermetic seal, in conjunction with particle/chemical filtration, and static shielding. Pressurization, inert gas purge, chemical absorbents, and electric grounding or air ionization are techniques of removing contaminants from the critical areas. For best performance, adequate selection of construction materials is critical. This paper discusses impacts of contamination on lithography processes and the possibility of solving such problems using SMIF isolation techniques. Theoretical models are developed and experimental data are presented.

Paper Details

Date Published: 22 August 2001
PDF: 9 pages
Proc. SPIE 4344, Metrology, Inspection, and Process Control for Microlithography XV, (22 August 2001); doi: 10.1117/12.436782
Show Author Affiliations
Sheng-Bai Zhu, Asyst Technologies, Inc. (United States)


Published in SPIE Proceedings Vol. 4344:
Metrology, Inspection, and Process Control for Microlithography XV
Neal T. Sullivan, Editor(s)

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