Akihiko Kishimoto

Minimization of X-Ray Mask Distortion by Two-Dimensional Finite Element Method Simulation

X-ray mask distortion caused by absorber stress is quantitatively analyzed by using two-dimensional simulation. Simulated results successfully predict the mask pattern distortion in practical mask structures. A square mask window is better than a circular one because the distortion for square windows can be minimized by reducing the pattern length. In addition, it is found that the maximum distortion is virtually the same regardless of the number of LSI chips within the square window mask.

High-Quality Carbon-Doped Boron Nitride Membrane for X-Ray Lithography Mask

Carbon-doped BN (BNC) membrane was fabricated by low pressure chemical vapor deposition (LPCVD) at a high temperature (750°C). Here, CH3NH2 was used as the reactive gas instead of NH3. The newly developed BNC has tensile stress and is transparent to visible light. A very small hydrogen content (3.3%) leads to the construction of strong atomic networks of B, N, and C, as well as to highly improved radiation stability.