JPS62118577A - Semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the diffusion of the metal atoms of metal silicide into a thin oxide film such as a gate oxide film, by forming a wiring film and a gate electrode on a thin oxide film with polysilicon, and forming a wiring film other than an element forming region by a double-layer structure of a polysilicon film, a metal film and the like. CONSTITUTION:An element isolating insulating film 12 is formed on a semiconductor substrate 11. A thin oxide film 13 is formed in an element forming region, which is defined by the film 12. A gate electrode and a connecting wiring film 14 for connecting the gate electrode on the oxide film 13 are formed with polysilicon. A wiring film 15, which is formed in a region other than the element forming region, is formed by a double-layer structure of a polysilicon film and a metal film, the polysilicon film and a metal silicide film, or the metal film and the metal silicide film. Since the polysilicon film is formed on the thin gate oxide film, metal atoms are not introduced, and withstanding voltage is not decreased. Since the metal film or the metal silicide film are formed in the other region, wiring resistance is eliminated, and therefore high speed operation is realized.

Description

[Detailed Description of the Invention] [Summary] In a thin oxide film such as a gate oxide film of an MO3 type semiconductor element formed in a region defined by a silicon oxide film for separating semiconductor elements, The wiring 11 of the polysilicon wiring film that connects - (11114 pressure of the A conductor device that can break) (! (Prevents F4. 11 people - Day 1
J, t (till
For connection between polysilicon and metal, or polysilicon and metal, or polysilicon and full-bend resiliency l゛ membrane, one metal lI and metal silicone] 'crotch one'J-horizontal j111 to speed up A barrel body device designed for this purpose.

[Industry-1, usage amount! lIf] The present invention relates to improvements in ``1'' conductor devices, particularly MOS type ``V conductor devices.

Semiconductor devices such as MO5 type LSIs are becoming increasingly denser and faster.

Like this 2r high speed MOS 't'! When manufacturing semiconductor devices, the CVI method was used to connect the elements constituting these semiconductor devices because it is easy to manufacture and the process can be carried out using -W. A milli-silicon wiring film is used.

However, since such a wiring film made of polysilicon has a high resistance, the resistance of the wiring connecting the elements constituting the semiconductor device becomes high, and it is difficult to obtain a semiconductor device that operates at high speed.

Therefore, silicide is used, in which metal atoms such as tungsten (W) and titanium (Ti) are introduced into the polysilicon that forms such wiring films to form intermetallic compounds between silicon and these metals. .

By the way, in MO3 type semiconductor devices, thin silicon dioxide: 1
A gate oxide film made of SiO2 film is formed in the element formation region defined by the element isolation oxide film, and the above-mentioned metal atoms are not introduced into this gate oxide film to reduce breakdown voltage. There is a demand for a semiconductor device with a structure that does not cause this phenomenon.

[Prior Art] Conventionally, when forming a MOS-type 14-conductor device using such a metal silicide film, as shown in FIG. 5i0
After forming 2H*2, a thermal oxidation method is used to form a first oxide film 3 made of a 5i02 film, and then a polysilicon and tungsten silicide 1 film is formed using a CVD method and a 1-lithography process. After forming a gate electrode 4, using this gate electrode 4 as a mask, phosphorus atoms are ion-implanted into the St substrate by an ion implantation method to form a source region 5 and a drain region 6.

Furthermore, the gate electrodes were made with a two-layer structure of polysilicon and metal silicide, which lowered the resistance of the wiring connecting the gate electrodes, allowing the devices to be formed at higher density, and the length of the wiring connecting the devices became longer. Even in this case, a semiconductor device having a polycide structure that operates at high speed is formed so that the arrangement 1i1 resistance does not increase.

[Problem to be solved by the invention Jc]

However, in such conventional polynide structure semiconductor devices, after forming the gate electrode, the surface of these semiconductor elements is protected [1], and the entire element is covered with a thermal oxide film as shown in Figure 7. 8 - [There is a culm, and this heat treatment step causes the metal atoms of the metal silicide film 7 to diffuse into the lower polysilicon gate electrode 4 and further gate oxidize the lower part of the polysilicon gate electrode. There was a problem in that it reached the film 3 and caused a drop in breakdown voltage of the semiconductor device to be formed.

The present invention solves the above-mentioned problems, and aims to provide a semiconductor device in which metal atoms of metal silicide for reducing wiring resistance are prevented from diffusing into a thin oxide film such as a gate oxide film. .

[Means for solving problems]

The semiconductor device of the present invention has isolation l1l111 between elements.
A wiring film 14 for interconnection between elements and a gate electrode are formed of polysilicon on the thin oxide film 13 formed in the element formation area defined by 2, and are formed in an area other than the element formation area. The wiring film 15 is formed of a two-layer structure of a polysilicon film and a metal film, a polysilicon film and a metal silicide film, or a metal film and a metal silicide film.

[Effect]

Semiconductor device H4;l of the present invention, 5I02+1 for isolation between elements
The thin gate oxide film 13 in the element formation area ff1 defined by 9! Alternatively, it is formed with a two-layer structure of polysilicon and metal silicide film, or metal and metal silicide film 1'', and prevents metal atoms from being introduced into the di-oxide film 13 to prevent a drop in breakdown voltage of the semiconductor device to be formed. , the wiring t1 (resistance (
1 (to obtain a semiconductor device that operates at high speed).

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view showing the structure of the semiconductor device of the present invention.
In particular, it is a cross-sectional view of a portion where the gate electrode is wire-connected, and is a cross-sectional view showing a state in which the above-described FIG. 7 is rotated by 90 degrees.

On a thin oxide film such as a gate oxide film 13 formed in a region defined by a 5I02 film 12 for element isolation formed on a P-type Si substrate 11 as shown in FIG. The wiring film 14 that connects between the rods or the gate electrodes is formed of a polysilicon film, and the wiring film 14 that connects the gate electrodes or between the gate electrodes is used for inter-element cutting 5102.
Film] The wiring film 15 formed in 2-h is formed of a metal silicide film such as a tungsten silicide film.

According to such a semiconductor device of the present invention, since a polysilicon film is formed on the thin gate oxide film 131, metal atoms are not introduced and a breakdown voltage does not decrease. Further, since the other regions are formed of metal or metal silicide film, the wiring resistance becomes ((<), and therefore, it operates at high speed.

The second method for manufacturing a semiconductor device of the present invention is as follows.
This will be explained using the figures up to FIG. 6.

First, as shown in FIG.
After forming i02 and gate oxide film 13 by thermal oxidation method,
A film for forming a gate electrode is formed on the substrate 11 using polysilicon 1.
After forming the silicon nitride film 17 on the entire surface of the substrate 11-1- in step 6, a silicon nitride film 17 is formed thereon.

Furthermore, a photoresist film 1B having a predetermined pattern is formed on the silicon nitride film 17-1- on a region corresponding to the gate oxide film 13.

Next, as shown in FIG. 3, using the photoresist film 18 as a mask, the silicon nitride film 17 is etched into a predetermined pattern using an etching gas consisting of a mixed gas of carbon tetrafluoride and oxygen gas. In the figure, 17^ is a silicon nitride film etched into a predetermined pattern.

Furthermore, as shown in FIG. 4, a metal film 19 made of tungsten is formed by sputtering using the silicon nitride I*I7A thus formed as a 'ζ mask.

Next, the substrate 11 shown in FIG. 4 is heated in a nitrogen gas atmosphere (the gold bisllll! 119 and the polysilicon film 16 formed thereunder are reacted to form a tungsten silicide film). 20. In this case, the lower part of the silicon nitride film 17A remains as the polysilicon film 16.

Furthermore, the substrate is etched using an esotynda solution consisting of a mixed solution of hydrogen peroxide (H2O2) and ammonia.

Then, since the etching rate of the metal film 19 is faster than that of the metal silicide film 20, the metal film is etched first and a thin gate oxide lI! is formed as shown in FIG. Polysilicon II on i13! 16 is formed, and a semiconductor device is formed in which a metal silicide film 20 is formed in other regions.

Thereafter, by etching away the silicon nitride layer 17A using phosphoric acid, as shown in FIG.
Since a low resistance wiring film 15 such as a metal silicide film 20 is formed on the i02 film 12, a semiconductor device that operates at high speed can be obtained.

Also, thin gate oxidation 1! of the element formation region defined by the 5i02 film 12 for element isolation! Since the wiring film 14 made of the polysilicon film 16 and the gate electrode are formed on the gate oxide film 13, metal atoms for forming the metal silicide ll1i20 film are not introduced into the gate oxide film 13. Prevents voltage resistance of semiconductor devices.

In addition to the present embodiment described above, the metal film formed on the polysilicon film may have a two-layer structure of polysilicon and metal H without performing heat treatment.

Furthermore, when forming the metal film 19 by CVD using the silicon nitride film 17A as a mask, the pressure of the reaction gas in CVD or the reaction temperature may be appropriately adjusted to form the silicon nitride film 19.
7^-1- may be formed using selective growth in which no metal film of W is formed.

Further, when etching the metal film, a mixed gas of carbon tetrafluoride gas and oxygen gas may be used.

〔Effect of the invention〕

As described above, according to the semiconductor device of the present invention, a two-layer structure of polysilicon and metal, polysilicon and metal silicide film, or metal film and metal silicide film is formed in the region other than the thin gate oxide film. Since the wiring resistance can be lowered, the speed of the formed device can be increased, and the polysilicon layer can be removed in the region of the gate oxide film 1-.
Since only the gate oxide film is formed, metal atoms are introduced into the gate oxide film, and a high-density conductor device with no low withstand voltage is observed.

[Brief explanation of drawings]

Figure 1 is a sectional view of the semiconductor device of the fourth invention, Figures 2, 1, and 6 are sectional views of the III! 1 is a sectional view showing the structure of a conventional semiconductor device. In the figure, 11 is an S1 group, 12 is a 5i02 film for isolation between elements, and 1
3 is a gate oxide layer, 14.15 is a wiring layer, 16 is a polysilicon film, +7. I7A is a silicon nitride film, 18 is a photoresist film, 19 is a tungsten film, and 20 is a metal oxide film. Present invention 1 ↓ Calling equipment
Gachi I\゛Work≠ [Fig.

Claims (1)

[Claims] An insulating film for isolation between elements (
The gate electrode on the thin oxide film (13) formed in the element formation region defined in 12) and the connection wiring film (14) connecting the gate electrode are formed of polysilicon, A wiring film (15) formed in a region other than the element formation region
) is formed of a two-layer structure of polysilicon and a metal film, a polysilicon film and a metal silicide film, or a metal film and a metal silicide film.