SNR200 chemically amplified resist optimization

A resist process using Shipley SNR200® chemically amplified (CA) resist has been characterized and optimized for the manufacture of 1x masks for x-ray lithography. This paper describes the processes and the experimental designs used to optimize the post-apply-bake (PAB) and post-expose-bake (PEB) that affect resist sensitivity and process latitude of SNR200 resist. The baking parameters were optimized for an electron-beam sensitivity of 20μC/cm 2 at 75kV using designed experiments, analyzed by SAS software, JMP®. This paper also shows the capability of the resist process to yield a minimum resolution < 0.125μm, a critical dimension (CD) uniformity < 20nm 3σ across a 25mm x 25mm membrane, and repeatability from membrane to membrane < 25nm 3σ. The dose compensation software required for electron-beam lithography to correct for electron scatter from the substrate, etc., was developed by IBM for their shaped-beam lithography systems and, with correct parameters, CD linearity plots show accurate replication to data designs ranging from 0.175μm to 0.4μm. The process latitude and robustness demonstrated shows that SNR200 resist is compatible with a manufacturing environment required for the fabrication of x-ray masks.