Comparative study of AZPN114 and SAL601 chemically amplified resists for electron beam nanolithography

With the minimum feature dimension of integrated circuits (ICs) shrinking to below 130 nm, the IC industry has to choose one among a number of nonoptical lithography tools. Electron beam direct write or mix-and-match lithography is an attractive choice because of the maturity of the technology and the potential of using the tool for several generations of ICs. The low throughput associated with e-beam direct writing of wafers can be significantly reduced by using chemically amplified resists. Two commercially avaliable negative tone chemically amplified resists, AZPN114 and SAL601, were investigated and compared for their performance in e-beam direct writing of wafers at 150, 100 and sub-50 nm resolutions. A number of factors influencing the throughput issue were evaluated The latitudes of postexposure bake and postexposure delay were compared. It is found that both resists are of high resolution and high contrast, with the highest resolution, 30 nm, achieved for AZPN114. AZPN114 has higher sensitivity and is more stable during postexposure delay than SAL601 but less stable during postexposure bake. A 6 in. industrial wafer was exposed with AZPN114 at gate level at 150 nm resolution using e-beam lithography and it showed feature uniformity across the entire wafer.