Damage characterization of SiN X-ray mask membrane caused by electron beam exposure

摘要

The effects of exposure damage with electron beam of 20 to 50 kV acceleration voltage on silicon nitride film prepared by LPCVD system have been investigated. It is shown that the optical and the mechanical properties of this material are modified and may potentially limit the use as a membrane in an X-ray mask structure for the high density memory devices of GDRAM level. Especially, the optical transmission of films exposed by electron beam with the acceleration voltage of 50 kV and the dosage of 900 µC/cm2 degraded about 17% in the wavelength range of 633 ± 10 nm. The differences in mechanical deflection on the membrane area of 800 x 800µm2 area which was, before and after. exposed by electron beam of acceleration voltage of 20 kV - 50 kV were shown about 500 A - 100 A. It was measured by the α-step(Tencor 200) with the stylus force of 19.6 dyne. The distortion of SiN X-ray mask membrane with alignment window was investigated by interferometric phase mapping.