US 5,970,328 A · Fabrication method of T-shaped gate electrode in semiconductor device

Abstract

A method for fabricating a T-shaped gate electrode of a high speed semiconductor device such as HEMTs which is applied to high speed logic circuit including low-noise receivers and power amplifiers having a frequency of X-band or more respectively, and MMICs having a frequency of millimeter wave band. Such devices require a short gate length and a large sectional area of the gate pattern. The conventional photolithography techniques are in need of the resolution for fabricating a fine line width. Therefore, electron-beam lithography is most widely used. But, it is difficult to enhance throughput in manufacturing semiconductor devices because a lot of exposure time is required in the methods using electron beams. In the present invention, a silicon oxide film or a silicon nitride film is deposited on a mono-layered resist pattern. A dummy pattern corresponding to a leg of the gate is formed using the silicon oxide film or the silicon nitride film. A leg of the gate electrode is formed at the portion of the dummy pattern. According to the present invention, a step for improving the resolution is not required, and a gate electrode having a very fine line width of a few hundreds .ANG. can be obtained by regulating the thickness of the silicon nitride film.

Claims16

Dependent claims

A method for fabricating a T-shaped electrode of a semiconductor device, comprising the steps of:

a. forming a first resist layer on a substrate of the semiconductor device;
b. forming a resist pattern by opening a portion of the first resist layer corresponding to a side of the point at which a leg of the T-shaped gate electrode will be formed;
c. depositing a first thin film for forming a dummy pattern for the leg on the resultant structure after step b.;
d. forming a second resist layer on the resultant structure after step c.;
e. removing the second resist layer by etching until a top layer of the first thin film is exposed;
f. etching the exposed portion of the first thin film to form the dummy pattern for the leg;
g. depositing a second thin film composed of the same material as the first thin film on the resultant structure after step f.;
h. forming a resist pattern for forming a head of the T-shaped electrode, through which a portion of the second thin film is exposed, by forming a third resist layer on the resultant structure after step g., exposing a portion of the third resist layer to light, and performing a development process to expose the portion of the second thin film;
i. etching the exposed portion of the second thin film and the portion of the first thin film which forms the dummy pattern for the leg;
j. depositing a metal layer for gate electrode on the resultant structure after step i.;
and
k. removing the residual first, second and third resist layers and the residual metal layer formed thereon.

9 more elements

A method for fabricating a T-shaped electrode having two legs in a semiconductor device, comprising the steps of:

a. forming a first resist layer on a substrate of the semiconductor device;
b. forming a resist pattern by opening a portion of the first resist layer, in which the two legs of the T-shaped electrode will be formed;
c. depositing a first thin film for forming dummy patterns for the two legs on the resultant structure;
d. forming a second resist layer on the resultant structure after step c.;
e. removing the second resist layer by etching until a top portion of the first thin film is exposed;
f. etching the exposed portion of the first thin film to form the dummy patterns for the two legs;
g. depositing a second thin film composed of the same material as the first thin film on the resultant structure after step f.;
h. forming a resist pattern for forming a head of the T-shaped electrode, through which a portion of the second thin film is exposed, by forming a third resist layer to light on the resultant structure after step g., exposing a portion of the third resist layer to light, and performing a development process to expose the portion of the second thin film;
i. etching the exposed portion of the second thin film and the portions of the first thin film which forms dummy patterns for the two legs;
j. depositing a metal layer for gate electrode on the resultant structure after step i.;
and
k. removing the residual first, second, and third resist layer and the residual metal layer formed thereon.

9 more elements

Dependencies are inferred from the claim text.

Fabrication method of T-shaped gate electrode in semiconductor device

Life of this patent

Fabrication method of T-shaped gate electrode in semiconductor device

Life of this patent

Abstract

Claims16