Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – Insulated gate formation
Reexamination Certificate
2000-06-12
2001-10-02
Niebling, John F. (Department: 2812)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
Insulated gate formation
C438S592000, C438S682000
Reexamination Certificate
active
06297137
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for forming a semiconductor device; and, more particularly, to a method for forming a gate electrode in a DRAM (Dynamic Random access memory) device.
DESCRIPTION OF THE PRIOR ARTS
Generally, semiconductor devices are divided into read/write memory devices and read only memory devices. Especially, in the read/write memory devices, a unit cell in the DRAM device has only one transistor and one capacitor so that the DRAM can achieves a highly integrated memory device. Accordingly, with the increase of the integration, 64 Mb DRAMs have been mass-produced and the researches to increase the productivity and yield thereof are steadily in progress.
Furthermore, 256 Mb DRAMs have been already developed and investigation goes deep into the study of 1 Gb DRAMs. In such a highly integrated memory device, for example, 1 Gb memory device, the line width may be about 0.08 &mgr;m
2
. Accordingly, the line width required in a gate electrode of a transistor is getting narrower. As a result, since gate electrodes, which are made of the conventional polysilicon or tungsten silicide layer, may not satisfy a low resistance with such a narrow line width, a low resistant material, such as TiSi
2
, CoSi
2
or W, have been used as a gate electrode.
However, it is very difficult to obtain high speed corresponding to such a high integration in mass production, by employing the silicide and metal layer as a gate electrode. That is, when gate conducting layers, such as W, TiSi
2
, and CoSi
2
layers are deposited on a gate insulating layer and these layer are etched through an etching mask for the gate electrode, the gate insulating layer deteriorates. To prevent this problem and protect a substrate in LDD (Lightly Doped Drain) ion-implantation, a re-oxidation process is carried out. However, this re-oxidation process causes the tungsten layer to be oxidized and deforms a word line of the patterned gate electrode.
Particularly, since the tungsten layer is characteristic of higher oxidation, the thermal stability of the tungsten gate electrode may not be guaranteed. Furthermore, the tungsten layer has a demerit in that the oxidation profile of the tungsten layer is considerably expanded so that it is very difficult to achieve a gap filling in forming an interlayer insulating layer.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a method for forming a gate electrode in a memory device, in especially DRAM.
It is another object of the present invention to provide a method for preventing a gate electrode from being oxidized in a thermal treatment.
In accordance with an aspect of the present invention, there is provided a method for forming a gate electrode in a semiconductor device comprising the steps of: forming a conducting layer for a gate electrode on a predetermined semiconductor substrate; forming a silicon layer on sidewalls of the conducting layer through a silicon ion implantation; forming a gate pattern by patterning the conducting layer using the etching barrier pattern for the gate electrode, thereby forming the gate electrode having the silicon layer on sidewalls thereof; and applying a thermal treatment to the semiconductor substrate.
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Blakely & Sokoloff, Taylor & Zafman
Hyundai Electronics Industries Co,. Ltd.
Lindsay Jr. Walter L.
Niebling John F.
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