Effect of dissolution inhibitors on the dissolution characteristics of chemically amplified positive-tone electron beam resist

摘要

The chemical amplification resist system composed of partially tBOC-protected PVP, a dissolution inhibitor, and an acid generator are investigated as EB resists. As dissolution inhibitors, hydroquinone protected with tert-butoxycarbonyl group (B-HQ) and isophthalic acid protected with tert-butyl group (B-IP) are utilized. It is found that dissolution rate of the resist consisting of B-IP is faster than that of B-HQ in the exposed area. B-HQ and B-IP as dissolution inhibitors convert into HQ and IP as dissolution promoters after exposure, respectively. The pKa of IP is smaller than that of HQ. It is considered that the acidity of IP is higher than that of HQ, so the ability of the dissolution promotion of IP is much larger than that of HQ. IP enhances the solubility of the matrix resin to the alkaline developer larger than HQ. The resist consisting of B-IP has a high dissolution rate ratio between the exposed and unexposed areas, so it is considered that it results in a much improved patten profile. A 0.14 $mu@m lines-and-spaces pattern is successfully fabricated at 17.5 $mu@C/cm$+2$/ using 50 keV. EB.