Photolithography yield enhancement due to reduced consumption of the usable depth of focus resulting from advanced wafer back surface clean processing

The continued growth of the semiconductor manufacturing industry has been due, in large part, to improved lithographic resolution and overlay across increasingly larger chip areas. Optical lithography continues to be the mainstream technology for the industry with extensions of optical lithography being employed to support 180 nm product and process development. While the industry momentum is behind optical extensions to 130 nm, the key challenge will be maintaining an adequate and affordable process latitude (depth of focus/exposure window) necessary for 10% post-etch critical dimension (CD) control. This paper addresses a number of direct and immediate benefits to the lithographic process yield at SEMATECH. The yield enhancement of the MicraScan III deep-ultraviolet (DUV) step-and-scan lithography system is a result of specific utilization of a set of flexible and reliable wafer back surface preclean processes developed on the SEZ Spin-Processor Model 203, configured for processing of 200 mm diameter wafers.