Chemically amplified negative resist for e-beam fabrication of x-ray masks

We are reporting on a chemically amplified negative-tone resist developed at IBM. The resist consists of three components: novolac resin, photoacid generator, and crosslinker. The resist is sensitive to DUV, e-beam, and x ray. However, this paper focuses on the e-beam application oriented toward x-ray mask fabrication. The mask process includes post-apply and post-exposure bake of membranes in a convention oven. The exposure was completed in an IBM EL-3+ system equipped with a variable axis immersion lens (VAIL). The membranes were developed in an APT processor with 0.03 N TMAH employing an interrupt develop process. The resist sensitivity ranged from 5 to 10 (mu) C/cm2 depending on the resist formulation and the process parameters. The contrast was found to be greater than 5.