METHOD FOR MANUFACTURING INSULATED-GATE TYPE FIELD EFFECT TRANSISTOR

Abstract

A poly-silicon layer is deposited on a surface of a substrate after forming a gate insulating film in an element hole of a field insulating film 12, and thereon a silicon oxide layer is formed by a thermal oxidation process. After patterning the silicon oxide layer in accordance with a gate electrode pattern, the poly-silicon layer is patterned by dry-etching using a remaining resist layer as a mask. After removing the resist layer, a gate electrode layer 16a is formed by decreasing a width of the poly-silicon layer by isotropic etching using the silicon oxide layer 18A as a mask. N+-type source and drain regions 22 and 24 and n−-type source and drain regions 26 and 28 are formed by doping impurity ions via the gate insulating film 14 through the silicon oxide layer 18A. The silicon oxide layer 18A may be made of a layer of tungsten silicide.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a substrate showing a poly-silicon deposition process in a method for manufacturing an insulated-gate type field effect transistor according to a first embodiment of the present invention.

FIG. 2 is a cross sectional view of the substrate showing a poly-silicon oxidation process following the process in FIG. 1.

FIG. 3 is a cross sectional view of the substrate showing a resist layer formation process and an isotropic etching process following the process in FIG. 2.

FIG. 4 is a cross sectional view of the substrate showing a dry-etching process following the process in FIG. 3.

FIG. 5 is a cross sectional view of the substrate showing a resist removing process following the process in FIG. 4.

FIG. 6 is a cross sectional view of the substrate showing an isotropic etching process following the process in FIG. 5.

FIG. 7 is a cross sectional view of the substrate showing an ion doping process following the process in FIG. 6.

FIG. 8 is a cross sectional view of the substrate showing an isotropic etching process following the process in FIG. 7.

FIG. 9 is a cross sectional view of the substrate showing an interlayer insulating film formation process and a wiring formation process following the process in FIG. 8.

FIG. 10 is a cross sectional view of a substrate showing a poly-silicon deposition process in a method for manufacturing an insulated-gate type field effect transistor according to a second embodiment of the present invention.

FIG. 11 is a cross sectional view of the substrate showing a WSi deposition process following the process in FIG. 10.

FIG. 12 is a cross sectional view of the substrate showing a resist layer formation process and an isotropic etching process following the process in FIG. 11.

FIG. 13 is a cross sectional view of the substrate showing a dry-etching process following the process in FIG. 12,

FIG. 14 is a cross sectional view of the substrate showing a resist removing process following the process in FIG. 13.

FIG. 15 is a cross sectional view of the substrate showing an isotropic etching process following the process in FIG. 14.

FIG. 16 is a cross sectional view of the substrate showing an ion doping process following the process in FIG. 15.

FIG. 17 is a cross sectional view of a substrate showing a first ion doping process in a method for manufacturing an insulated-gate type field effect transistor having an LDD structure according to a prior art.

FIG. 18 is a cross sectional view of the substrate showing an isotropic etching process following the process in FIG. 17.

FIG. 19 is a cross sectional view of the substrate showing a resist removing process and a second ion doping process following the process in FIG. 18.

Claims

1. A method for manufacturing an insulated-gate type field effect transistor, comprising the steps of: preparing a semiconductor substrate of which at least a part of one main surface has a first conductivity type;forming an isolation region for demarcating an element arrangement region corresponding to the part of one main surface of the semiconductor substrate;forming a gate insulating film on a semiconductor surface in the element arrangement region;forming a conductive material layer on the gate insulating film;forming a hard mask material layer above the gate insulating film via the conductive material layer;forming a resist layer on the hard mask material layer by a photolithography process in accordance with a desired gate electrode pattern;performing an etching process using the resist layer as a mask to the hard mask material layer to form a hard mask composed of a part of the hard mask material layer remaining in accordance with the gate electrode pattern;performing an anisotropic etching process using the resist layer as a mask to the conductive material layer to remain a part of the conductive material layer in accordance with the gate electrode pattern;removing the resist layer;performing an isotropic etching process using the hard mask as a mask to decrease a width of a remaining part of the conductive material layer so as to form a gate electrode layer composed of the remaining part of the conductive material layer of which width is decreased; andforming a source and a drain regions having a second conductivity type opposite to the first conductivity type respectively in one and another side of the gate electrode layer by performing an impurity ion doping process using a lamination of the gate insulating film, the gate electrode film and the hard mask and the isolation region as a mask, wherein an ion doping depth in a first part of each of the source and the drain regions under the mask where the hard mask is not overlapped with the gate electrode layer is shallower than an ion doping depth in a second part of each of the source and the drain regions that is not covered by the mask by doping the impurity ions to the first part of each of the source and the drain regions via the mask where the hard mask is not overlapped with the gate electrode layer.

2. The method for manufacturing an insulated-gate type field effect transistor according to claim 1, wherein the hard mask is formed to have a width narrower than a width of the resist layer by using an isotropic etching process for the etching process.

3. A method for manufacturing an insulated-gate type field effect transistor, comprising the steps of: preparing a semiconductor substrate of which at least a part of one main surface has a first conductivity type;forming an isolation region for demarcating an element arrangement region corresponding to the part of one main surface of the semiconductor substrate;forming a gate insulating film on a semiconductor surface in the element arrangement region;forming a conductive material layer on the gate insulating film;forming a hard mask material layer above the gate insulating film via the conductive material layer;forming a resist layer on the hard mask material layer by a photolithography process in accordance with a desired gate electrode pattern;performing an anisotropic etching process using the resist layer as a mask to the hard mask material layer and the conductive material layer to form a hard mask composed of a part of the hard mask material layer remaining in accordance with the gate electrode pattern and simultaneously to remain a part of the conductive material layer in accordance with the gate electrode pattern;removing the resist layer;performing an isotropic etching process using the hard mask as a mask to decrease a width of a remaining part of the conductive material layer so as to form a gate electrode layer composed of the remaining part of the conductive material layer of which width is decreased; andforming a source and a drain regions having a second conductivity type opposite to the first conductivity type respectively in one and another side of the gate electrode layer by performing an impurity ion doping process using a lamination of the gate insulating film, the gate electrode film and the hard mask and the isolation region as a mask, wherein an ion doping depth in a first part of each of the source and the drain regions under the mask where the hard mask is not overlapped with the gate electrode layer is shallower than an ion doping depth in a second part of each of the source and the drain regions that is not covered by the mask by doping the impurity ions to the first part of each of the source and the drain regions via the mask where the hard mask is not overlapped with the gate electrode layer.