Techniques to inspect SCALPEL masks

As semiconductor lithography nodes become increasingly difficult to achieve with traditional optical lithography, several new technologies have emerged. SCALPEL (SCattering with Angular Limitation Electron beam Lithography) is at the forefront of the NGL technologies. SCALPEL technology uses an electron beam rather than laser light to produce images on the wafer. The SCALPEL mask is non-traditional in the sense that it is silicon-based instead of glass-based and the patterns are written on a membrane. SCALPEL provides unique challenges for the mask maker as well as the semiconductor manufacturer. In this study, we have demonstrated that the KLA-Tencor 3XX platform is capable of inspecting prototype SCALPEL reticles for pattern defects. The inspections were performed with two light wavelengths: 488 nm and 365 nm. Included are the difficulties faced and a projected roadmap for the inspection tool when SCALPEL enters at the 100 nm technology node.