Reduction of x-ray irradiation-induced pattern displacement of sin membranes using H⁺ion implantation technique

We have developed a technique for improving X-ray irradiation stability of silicon nitride (SiN) X-ray mask membrane using H⁺implantation. This technique can realize the reduction of X-ray irradiation-induced patterndisplacement to less than 20 nm after X-ray absorption with a dose of 30 MJ/cm³by optimizing the implantationdose to 4 x 10¹⁵/cm²at 150 keV. It is found that the mechanism of the reduction of the displacement is that thestress change after X-ray absorption in the implanted layer (top to 1.1 μl in depth) of SiN film compensates thestress change in the unimplanted layer (l.l to 2.0 μn (bottom) in depth).