On-wafer spectrofluorometric method for determination of relative quantum yields of photoacid generation in chemically amplified resists

Chemically amplified resists (CARs) that employ acid catalysts are widely u sed throughout the semiconductor industry due to the need for high throughp ut in the lithography process. The quantum yield of the particular photoaci d generator (PAG) used to generate a given acid ultimately limits the photo speed of the CAR. Determination of quantum yields of photoacid generation i s therefore an important component of resist design, Mie report the develop ment of an on-wafer spectrofluorometric technique for this purpose. This te chnique is based on one first reported by Feke et al. (J. Vac. Sci. Technol . 2000, B18, 136-139), which involves doping the resist formulations contai ning the candidate PAGs with a fluorescent pH indicator dye, coating one wa fer per PAG, patterning the wafers with a dose ramp, and spectroscopically imaging the wafers. The response curve of each FAG is spatially and spectra lly encoded in the fluorescence images of each wafer. We investigate the ef ficacy of coumarin 6, a dye that was introduced as an acid sensor by Pohler s et al, (Chem, Mater. 1997, 9, 3222-3230) for this application, We further apply this technique to the determination of the quantum yield of photoaci d generation of four candidate PAGs for prototype 193-nm CARs, This techniq ue is convenient, fast, robust, and nondestructive.