Evaluation of Mask Soaking Performance in a Thermally Stabilized Vacuum Chamber in an Electron Beam Mask Writer

概要

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A temperature difference between a mask and a writing environment, which occurs during mask loading, is one of the most significant sources of the mask image placement error. The temperature of the mask has to be adjusted in a thermal chamber. To realize a rapid and highly accurate thermal soaking process, we constructed a new thermally stabilized vacuum chamber with an improved thermal soaking efficiency and evaluated its performance. The chamber is equipped with the top and bottom thermal stabilization plates (TSPs). It was found that the soaking time is largely dependent on the emissivities of the TSPs. The soaking relaxation time of less than 0.4 h is achieved. The thermal stability of the mask after soaking is 0.004°C ($3\sigma$) for 12 h. It was also found that a high TSP emissivity is effective in reducing the influence of the temperature variation of the environment on the mask, and the temperature variation of the mask is reduced to approximately 28% of that of the environment. A quick soaking and stable temperature holding of the mask are realized.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2004-06-15