Electronics and Telecommunications Research Institute

Sang-Soo Choi

Hyung-Joun Yoo

Byung-Sun Park

Yong-Ho Oh

Hyung-Moo Park

Chul-Soon Park

Jin-Hee Lee

Hyung-Jun Yoo

Hyung-Sup Youn

A method for making a T-shaped gate of a field effect transistor is disclosed. The method includes the steps of sequentially depositing first and second photoresist layers on a semiconductor substrate and performing an exposure using electron beams having different energy, one of the electron beams having a first energy to lightly expose only the second photoresist layer and the other of the electron beams having a second energy to lightly expose all of the first and second layers. The invention reduces gate resistance and parasitic capacitance of the T-shaped gate.

Method for making T-gate of field effect transistor

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 Fe.sub.2 O.sub.3, 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.

Photomask for forming T-gate electrode of the semiconductor device

The present invention relates to a photomask for forming a T-shaped gate structure on a high speed FET through a photolithography, comprising opaque layer patterns 2 and 2a for defining a head portion of the T-shaped gate structure and half-tone layer patterns 3 and 3a for defining a foot portion thereof. The half-tone film patterns composed of a chrome layer are deposited to a thickness thinner than that of the opaque layer patterns so that the half-tone layer patterns show a relatively lower transmittance to an incident beam. The application of the photomask of the invention to the process for forming a T-shaped gate structure improves process reproducibility and leads to great cost savings.

Photomask for t-gate formation and process for fabricating the same

Growing community of inventors

Yusong-ku, South Korea

Sang-Soo Choi