Critical-dimension controllability of chemically amplified resists for X-ray membrane mask fabrication

The key issues in highly precise X-ray mask fabrication are the high-perfor mance 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 chemi cally amplified resist, the high resolution and the excellent critical-dime nsion (CD) uniformity of 50-100 nm line-and-space and isolated-space featur es were obtained with no proximity correction, Temperature uniformity of va rious hot plate bakers during the post-exposure bake process and CD control lability of pattern size with chemically amplified resists were studied and the 3 sigma variation of pattern size written in a membrane using chemical ly amplified resists was reduced to less than 10 nm with an optimized hot p late 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 th an half of those with conventional ZEP-520 resist, while the resolution cap ability and CD accuracy of the membrane mask with chemically amplified resi st UV6-SL were almost equal to those with ZEP-520.