Photoresist Deposition Without Spinning

A technique for resist deposition using a novel fluid ejection method is presented in this paper. An ejector has been developed to deposit photoresist on silicon wafers without spinning. Drop-on-demand coating of the wafer reduces waste and the cost of coating wafers. Shipley 1400-21, 1400-27, 1805, and 1813 resists were used to coat sample 3and 4-in wafers. Later, these wafers were exposed and developed. The deposited resist film was 3.5 m thick and had a surface roughness of about 0.2 m. The ultimate goal is to deposit resist films with a thickness of the order of 0.5 m and a surface roughness of the order of 30 A, which is currently achieved for 200-mm silicon wafers by using a spinning method. Such goals can be attained by using micromachined multiple ejectors or with better control over the deposition environment. In the micromachined configuration, thousands of ejectors are made into a silicon die, as presented by Perçin et al. (2002), and thus allow for a full coating of a wafer in a few seconds. Coating in a clean environment will allow the lithography of circuits for microelectronic applications. Other potential applications for the technology in the semiconductor manufacturing are in deposition of lowmaterials, wafer cleaning, manufacturing of organic LEDs and organic FETs, direct lithography, nanolithography, and coating for hard-disk drives.