OPTICALLY HIGH TRANSPARENT SIN MASK MEMBRANE WITH LOW STRESS DEPOSITED BY LOW-PRESSURE CHEMICAL VAPOR-DEPOSITION

Optically high transparent and low-stress silicon nitride film for X-ray mask membrane was successfully deposited by low pressure chemical vapor deposition (LPCVD). Deposition of silicon nitride films in a relatively higher temperature range of 900-degrees-C-1000-degrees-C was investigated as a function of deposition temperature and reactant gas flow (SiH2Cl2 and NH3). Silicon nitride films of low tensile stress in the order of 3 - 5 x 10(8) dyn/cm2 with low refractive index of 2.05 were obtained at 1000-degrees-C. Silicon nitride membrane deposited at 1000-degrees-C showed optical transparency approximately 95% (lambda=633 nm). Use of such optically high transparent silicon nitride film will be helpful in reducing the alignment signal detection error, which is required for highly efficient mask wafer alignment.