《Electronics Letters》1991年10月报道了日本三菱电气公司利用光学和电子束曝光相结合的方法制造了超低噪声HEMT。在改进HEMT低噪声特性方面,同时减小栅长和降低寄生电阻极为有效。对于栅长小于0.25μm的HEMT而言,作好T型栅是至关重要的。以往常采用多层光刻胶和多次电子束曝光剥离金属工艺方法制造T型栅,但该工艺不适于大批量生产。 Electronics Letters reported in October 1991 that Mitsubishi Electric Corporation of Japan made use of a combination of optical and electron beam lithography to create an ultra-low noise HEMT. In improving the HEMT low noise characteristics, it is extremely effective to reduce the gate length and reduce the parasitic resistance at the same time. For a HEMT with a gate length of less than 0.25 μm, making a T-gate is of paramount importance. Traditionally, multi-layer photoresists and multiple electron beam exposure lift-off metal processes have been used to fabricate T-gates, but the process is not suitable for mass production.