Bright peak enhanced x-ray clear phase mask

TLDR: The clear bright peak enhanced x-ray phase mask (BPEXPM) as discussed by the authors employs the constructive interference of spatially coherent radiation as opposed to the destructive interference that is used in all the other phase-shifting schemes.

Abstract: A clear bright peak enhanced x-ray phase mask (BPEXPM) is described. It employs the constructive interference of spatially coherent radiation as opposed to the destructive interference that is used in all the other phase-shifting schemes. This type of mask shows ultrahigh resolution imaging, feature reduction from the mask critical dimension (CD), and enhanced transmission. It has been simulated and verified experimentally with a 320 nm mask CD. Specifically, the BPEXPM exhibits: (1) approximately three times higher effective sensitivity, 40 mJ/cm2 dose to mask for Shipley XP-9947E, a positive-tone chemically amplified resist that normally has a sensitivity of 120 mJ/cm2 in the x-ray region and (2) resolution of 54 nm features in XP-9947E at a 50 μm gap for a 320 nm mask CD. The simulation for the BPEXPM also predicts a wafer image CD of 31 nm at 10 μm gaps with a 150 nm mask CD.