Critical-Dimension Controllability of Chemically Amplified Resists for X-Ray Membrane Mask Fabrication

Abstract

The key issues in highly precise X-ray mask fabrication are the high-performance electron beam writer and the mask process on a thin membrane. By the combination of 100 kV electron beam system EB-X3 and highly sensitive chemically amplified resist, the high resolution and the excellent critical-dimension (CD) uniformity of 50-100 nm line-and-space and isolated-space features were obtained with no proximity correction. Temperature uniformity of various hot plate bakers during the post-exposure bake process and CD controllability of pattern size with chemically amplified resists were studied and the 3σ variation of pattern size written in a membrane using chemically amplified resists was reduced to less than 10 nm with an optimized hot plate baker. As a result, the e-beam sensitivity and writing time for 4G-bit level ULSI patterns of chemically amplified resist were reduced to less than half of those with conventional ZEP-520 resist, while the resolution capability and CD accuracy of the membrane mask with chemically amplified resist UV6-SL were almost equal to those with ZEP-520.