Thermal characteristics of scattering stencil reticle for EB stepper

Electron Beam (EB) projection system is proposed as a candidate of next generation lithography systems for feature sizes of less than 100nm. We are developing this technology as "EB stepper" that has high resolution and throughput. EB projection system also needs a development of EB reticle. A scattering stencil type (thin silicon membrane with openings representing the pattern to be exposed) reticle with a grid-grillage structure is being investigated. In the case of a conventional cell projection mask which consists of absorbers and apertures, the deformation caused by thermal expansion can not be ignored for a quarter-micron lithography. The temperature at the beam position rises drastically with the irradiation power of EB. We evaluated the deformation of a scattering stencil reticle, due to thermal expansion and bending by gravity.