| 摘要 |
A photomask according to the present invention for forming a T-gate electrode for Metal Semiconductor Field Effect Transistor and High Electron Mobility Transistor by performing each of the exposing process and the developing process once is disclosed. The photomask is composed of a primary mask positioned at the top surface of the transparent substrate made of Silica glass and a secondary mask positioned at the top surface of the transparent substrate for enhancing the resolution of the primary mask. The primary mask includes an opaque layer in which a material for mask pattern of, for example, Cr or Fe2O3, or other opaque materials is deposited at the bottom surface of the transparent substrate, thereby preventing the light radiated from being transmitted, and a first and second patterns for forming the leg portion and the head portion of the T-gate electrode by simultaneously radiating the light into the exposed portion of the transparent substrate. The secondary mask includes a phase shifting part for shifting the phase of the light so radiated to effect the diffraction and interference phenomenon of the light transmitted through the predetermined portion of the top surface of the transparent substrate, which is etched to a predetermined extent, and an optical transmissive part for transmitting the light as it is, without shifting the phase of the light. According to the present invention, a simplified photoresist pattern for forming a T-gate electrode of the semiconductor device can be obtained by applying the exposing process and the developing process once onto a single layer of the resist, using the photolithography. The superior resolution ability can also be achieved by controlling the diffraction and interference phenomenon of the light transmitted through the phase shifting part and the transmissive part of the secondary.
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