一、引言近几年来砷化镓材料和器件工艺方面的改进,实现了截止频率进入微波领域的场效应晶体管。肖特基势垒栅器件取代了扩散栅器件,因而使工作频率大大提高。为进一步提高这些器件的工作频率,必须采用栅长非常短的结构,器件要在10千兆赫以上的频率工作,则需制作亚微米的栅长。这在工艺中将产生很大的问题:由于要确定的尺寸接近紫外线辐射曝光的波长,普通的接触光刻掩模技术就不适用了。已提出新的工艺来缩小普通光刻带来的局限性, I. INTRODUCTION In recent years GaAs materials and devices have improved process technology to achieve the cutoff frequency into the microwave field of field-effect transistors. Schottky barrier device replaces the diffusion gate device, thus greatly improving the operating frequency. To further increase the operating frequency of these devices, a very short gate length structure must be used. Sub-micron gate lengths are required to operate at frequencies above 10 GHz. This poses a major problem in the process: the conventional contact lithography mask technique is not suitable due to the fact that the size to be determined is close to the wavelength of UV radiation exposure. New processes have been proposed to reduce the limitations of conventional lithography,