JPS59132677A - Manufacture of thin film transistor - Google Patents

Abstract

PURPOSE:To prevent the deterioration of gate withstand voltage by uniformly forming a gate insulation film and eliminate the possibility of disconnections of a wiring metal at the stepwise difference in a flat structure by covering an active element region with a selective oxide film. CONSTITUTION:A polycrystalline Si 302 is deposited on an insulation substrate 301, and then an oxide film 303 is formed by thermal oxidation. Next, after forming and processing the polycrystalline Si serving as a gate electrode 304, an oxide film 305 is formed by thermal oxidation. Then, an Si nitride film 306 is formed at the active element region, and processed, element isolation is performed by selectively oxidizing the polycrystalline 302 with the film as a mask, and then the Si nitride film 306 is removed. Thereafter, the source and drain regions 308 are formed by ion-implanting boron, etc. Finally, a contact hole for leading out the wiring is formed after depositing an NSG film serving as an interlayer insulation film 309, or a PSG film over the entire surface, and the wiring metal 310 such as Al is wiring-formed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an fC thin film transistor (hereinafter abbreviated as TPT) using polycrystalline silicon, and is a 7ζ device that aims to improve customization and stabilize the manufacturing process.

The first culprit is the conventional polycrystalline silicon TFT.

Here, 101 is a disconnected substrate, 102 is a polycrystalline silicon thin film, 105μ gate insulating film, 104 is a gate electric current, 105
μ source/drain diffusion, 106 μ source/drain diffusion,
107 is a metal part for wiring.

That is, after depositing polycrystalline silicon on the insulating substrate 101, ffr
After forming and processing into a certain pattern, a gate edge film 103'i is formed by an OVD method or a thermal oxidation method. Forming polycrystalline silicon 104, which will become the gate.
A source/drain diffusion layer 1057 is formed by implanting silicon ions such as phosphorus, arsenic, and boron into the processed material.

After debossing the entire N2O group or PE1G film, which will become the 111-layer film, contact holes for wiring are formed, and finally KA[! , Form a metal wire for wiring such as AN-Eli.

By the above manufacturing method, the TPT shown in FIG. 1 is formed.

The conventional structural TPT described above has the following drawbacks. That is, when a gate insulating film is formed, the portion of the gate insulating film on the side surface of the polycrystalline silicon thin film close to the insulating substrate becomes wide, resulting in deterioration of gate breakdown voltage. Because of the large steps between the housing and the elements, there is a risk of the metal wiring breaking. As a structure that can overcome all of the above drawbacks, there is a method in which the active element region is formed by selective oxidation, as shown in FIG. In FIG. 2, 201 is an insulating substrate, 202 is a polycrystalline silicon thin film, 203 is a gate insulating film, 204 is a gate electrode, 205 is a selective oxide film, 20
6 is a source/drain region, 207 is an interlayer insulating film, 20
8 is a wiring metal.

If the active element region is formed by selective oxidation as shown in FIG. 2, the above-mentioned drawbacks can be overcome.

The object of the present invention is a method of manufacturing TPT that can provide the above-described structure.

Hereinafter, an embodiment of the invention will be described with reference to process cross-sectional diagrams according to Figure @5.

In FIG. 5(a), polycrystalline silicon 30 is placed on an insulating substrate 301.
2&- debo and thermally oxidize the surface to form an oxide film 50.
form 5. This oxide film also serves as a gate insulating film. Next, polycrystalline silicon 504 that will become the gate electrode is formed and processed.
After c, an oxide film 305 is formed on the gate electrode by thermal oxidation. Next, as shown in FIG. 4B, a silicon nitride film 306 is formed and processed in the active element region.

Using the silicon nitride film as a mask, polycrystalline silicon is selectively grown to completely isolate the elements, the silicon nitride film is completely removed, and silicon ions such as phosphorus, arsenic, and poron are implanted to form the source/drain regions 308. N8, which ultimately becomes the 1-Bonno lamina (see figure (c)), was formed.
G film, or riPSG film 309 with all 309 debossed,
A contact hole is formed for drawing out the wiring, and the formation/MS
The same figure (a) shows wiring formed by wiring metal such as i.

According to the above manufacturing method, since the active element region is covered with a selective oxide film, the gate insulating film can be formed uniformly, so there is no deterioration in gate breakdown voltage, and since the structure is flattened, there are no steps. There is no risk of curved edges of the wiring metal at the parts.

As described above, improvements in the characteristics of Ic and TPT, and
This is a manufacturing method that provides a structure that stabilizes the manufacturing process.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a structure manufactured by a conventional method.
FIG. 2 is a cross-sectional view of a structure manufactured according to the invention. FIG. 3 is a process sectional view showing the manufacturing method according to the present invention. 301...Insulating substrate 302...Polycrystalline silicon 303...Oxide film (covering gate insulating film) 304...
・Gate electrode 305...thermal oxide film 506...
・Silicon nitride film 307...Selective oxide film 308・
...Source/drain region 309...Interlayer insulating film 310...Metal for wiring and above Applicant Suwa Kenkosha Co., Ltd. Agent Patent Attorney Tsutomu Mogami 5- Wing Figure 2 Figure 3-391-

Claims (1)

[Claims] In thin film transistors in which elements are separated by selective oxidation of polycrystalline silicon, which is the semiconductor base material, there is a process of forming an oxide film on the surface of polycrystalline silicon, which is the gate electrode, and a process of forming a silicon nitride film into a pattern of omnipotent @ region. A method for manufacturing a thin film transistor, the method comprising: a step of performing selective oxidation as the silicon film mask;