JPS6199347A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form a high quality transistor element, by performing beam annealing, etching away the surface of a contaminated single crystal semiconductor layer by high temperature fusion by one time, performing oxidation, and forming the new second semiconductor oxide film. CONSTITUTION:At first a polycrystalline silicon film 13' is deposited on a silicon substrate 11, on which SiO2 film 12 is formed, by a CVD method. This film is patterned. Then a continuous argon laser beam is scanned, and the polycrystalline silicon film 13'l is heated and fused. The film is converted into a single crystal silicon film 13. Thereafter, aresenic ions are implanted in the entire surface of the single crystal silicon film 13, and the single crystal silicon 13 is made to be an N type. Then, the surface of the single crystal silicon film 13 is oxidized, and an SiO2 film 14 is formed. Thereafter, the SiO2 film 13 is etched away by fluoric acid liquid. Then, the surface of the single crystal silicon film 13 is oxidized again. A gate insulating film 15 comprising the second SiO2 film is formed. A single crystal silicon film is deposited on the film 15 by using a CVD method. The film is patterned, and a gate electrode 16 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a semiconductor device, and particularly to a method for manufacturing an SOI structure semiconductor device.

Semiconductor integrated circuits (ICs) are LSI, VLSI, and two-dimensional (
WLIII and high integration have been achieved in the planar) area,
There is a limit to miniaturization, and as a means to further increase integration, we are currently using three-dimensional L
SI is getting a big close-up.

The basis of this type of 3D LSI is SOT.
It is a semiconductor device with a (Silicon On In5ulator) structure, which is manufactured by depositing a non-single-crystalline semiconductor layer on an insulating substrate, converting it into a single crystal by beam annealing, and forming a device on the single-crystal semiconductor layer. Created.

In this way, such a semiconductor element is formed into a three-dimensional LSI by being multilayered through an insulating film, and,
A semiconductor element having this SOI structure has the advantage of higher performance and higher integration than a semiconductor element formed on a conventional semiconductor substrate.

For example, when forming an IC consisting of five CMO elements, since the semiconductor region is on an insulating film, there is no need to worry about latch-up in terms of characteristics, and furthermore, there is no need for a channel stopper. If the channel stopper region is removed, the degree of integration is further increased.

However, it is desired that the semiconductor element provided in such a single crystal semiconductor N (semiconductor film) be an element of as high quality as possible, and the present case relates to improving the quality of such a semiconductor element.

[Prior Art] Now, as a semiconductor element having such an SOI structure, a MOS transistor is generally used, and is configured as, for example, a RAM memory.

An example of a conventional method for forming this SOI structured MOS transistor element will be described. FIGS. 2(a) to dl are cross-sectional views in the order of the process. First, as shown in FIG. 2(a), silicon dioxide (S
An iO2) film 2 is formed, and a polycrystalline silicon film 3° is deposited on the insulating film by chemical vapor deposition (CVD) and patterned.

Next, as shown in FIG. 2), a continuous argon laser (CW-Ar La
5er) scan the beam to heat and melt it,
The polycrystalline silicon film is transformed into a single crystalline silicon film 3.

That is, when the polycrystalline silicon film 3' is heated and melted by scanning the laser beam in a fixed direction and solidified, the single crystal silicon film 3 grows along the scanning direction.

Next, as shown in FIG. 2(C), arsenic ions are implanted into the entire surface of the single crystal silicon film 3 to form the single crystal silicon film 3.
After making n-type, the upper surface of the single-crystal silicon film 3 is oxidized to form a gate insulating film 4 several hundred thick, and a gate electrode 5 made of a polycrystalline silicon film is formed thereon. At this time, the gate insulating film 4 is heated to approximately 950°C in a hydrochloric acid gas atmosphere.
The silicon film 3 is formed by heating to oxidize the surface thereof. or,
The gate electrode 5 is formed by depositing a polycrystalline silicon film using the CVD method and patterning the film.

Next, as shown in FIG. 2(d), boron ions are implanted from the top surface to form p-type source regions on both sides of the gate electrode 5.
A drain region 6 is formed, and a phosphorus silicate glass (
A MOS transistor is completed by depositing a PSG film 7, opening a window thereon, and connecting an aluminum electrode 8.

[Problems to be solved by the invention] By the way, such a formation method has already been applied to SOI structures.
This is a well-known and widely used method for forming general MOS structures other than the MOS structure. However, in the case of a MOS transistor having an SOI structure, there is a problem in that the quality of the gate insulating film 4 produced by surface oxidation is not very good.

This is thought to be because the single crystal silicon film 3 is directly irradiated with a laser beam, causing surface contamination.When irradiated with a laser beam, the silicon film 3
As it melts at temperatures exceeding ℃, oxygen and dust from the atmosphere are absorbed into the oxide film that is forming on the surface. Therefore, it is estimated that problems such as gate breakdown voltage deterioration, surface states increasing and leakage current increasing, and threshold voltage fluctuations occur.

The present invention proposes a method for forming an SOI structure semiconductor device that eliminates these problems and forms a high-quality transistor element.

[Means for solving the problem] The problem is solved by beam annealing an amorphous semiconductor layer to transform it into a single crystal semiconductor layer, oxidizing the surface of the single crystal semiconductor layer to generate a semiconductor oxide film, Next, after removing the semiconductor oxide film by etching, the surface of the single crystal semiconductor layer is oxidized again to produce a second semiconductor oxide film, and the second semiconductor oxide film is used as a component of a semiconductor device. This can be solved by the manufacturing method.

[Operation] That is, the surface of the single crystal semiconductor layer that has been contaminated by beam annealing (beam irradiation) is melted at a high temperature and is once etched and removed, and then oxidized again to form a new second semiconductor oxide film. . The new semiconductor oxide film is then used for device components such as the gate insulating film.

In this case, the second semiconductor oxide film is not contaminated, so that the quality of the semiconductor element can be improved.

[Example] Hereinafter, embodiments will be described in detail with reference to the drawings.

FIGS. 1(a) to 1(f) show sequential cross-sectional views of the forming steps according to the present invention. First, as shown in FIG. 1(a), a polycrystalline silicon film 13 with a thickness of 4000 nm is deposited on the upper surface of the silicon substrate 11 on which the IO2 pattern 12 is formed by CVD method, in which monosilane gas is decomposed and deposited. ′ is deposited and patterned.

Next, as shown in FIG. 1(b), a continuous argon laser beam is scanned to heat and melt the polycrystalline silicon film 13° and transform it into a single crystal silicon film 13.

At this time, the silicon substrate is heated to about 450° C., and the laser annealing conditions are a laser output of 8 to 10 W, a beam spot diameter of 30 to 50 μmφ, and a scanning speed of about 10 cm/sec.

Next, as shown in FIG. 1C, arsenic ions are implanted into the entire surface of the single crystal silicon film 13 to make the single crystal silicon film 13 n-type, and then the surface of the single crystal silicon film 13 is oxidized. The film thickness is 200 to 400 silicon dioxide (
A SiO2) film 14 is produced. The generation conditions are, for example, heating to a temperature of 950°C and high humidity oxygen gas.

Or oxidize in a hydrochloric acid gas atmosphere.

Next, as shown in FIG. F(d), the 5i02 film 14 is removed by etching with a hydrofluoric acid solution.

Next, as shown in FIG. 1(e), the surface of the single-crystal silicon film 13 is oxidized again to form a second gate insulating film 15 made of 5toz1*, and then a CVD method is applied thereon. Then, a polycrystalline silicon film is deposited and patterned to form a gate electrode 16.

At this time, for the formation of the gate insulating film 15, it is preferable to take special care to reduce the mixing of oxygen, and to perform the process at a low temperature of 950° C., for example, in a high-pressure hydrochloric acid gas atmosphere.

Next, as shown in FIG. 1 (fl), boron ions are implanted by a known method to form a source region and a drain region 17 on both sides of the gate electrode 16, and then a PSG film 18 is formed.
Then, a window is opened to form an aluminum electrode 19.

In this way, the contaminated SiO□ film 14 is once removed by etching, and a second 5i02 film 15 of good quality is produced, which becomes a gate insulating film. Therefore, characteristics such as gate breakdown voltage of the MOS transistor are improved and variations thereof are reduced.

[Effect of the invention] As is clear from the above explanation, according to the present invention, sor
In the method for manufacturing a structural semiconductor element, a high quality insulating film is formed, which has the effect of improving the quality of the semiconductor element.

Note that although the above example has been explained using a gate insulating film, it goes without saying that the present invention can also be applied to insulating films of other transistors.

[Brief explanation of drawings]

FIGS. 1(a) to (f) are process cross-sectional views for explaining the forming method according to the present invention, and FIGS. 2(a) to (d) are process cross-sectional views for explaining the conventional forming method. It is a diagram. In the figure, 1.11 is a silicon substrate, 2.12 is an insulating film, 3', 1
3' is a polycrystalline silicon film, 3.13 is a single crystal silicon film,

Claims (1)

[Claims] The amorphous semiconductor layer is beam-annealed to transform it into a single-crystal semiconductor layer, the surface of the single-crystal semiconductor layer is oxidized to produce a semiconductor oxide film, and then the semiconductor oxide film is removed by etching. A second layer is formed by oxidizing the surface of the crystalline semiconductor layer.
1. A method of manufacturing a semiconductor device, comprising: producing a second semiconductor oxide film, and using the second semiconductor oxide film as a component of a semiconductor element.