JPH0799742B2 - Method for manufacturing semiconductor device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for easily removing a natural oxide film at a low temperature, and particularly to an application to a solid phase epitaxy process for realizing a three-dimensional circuit device. It is suitable.

[Outline of Invention]

The present invention relates to a solid phase epitaxy method in which amorphous or polycrystalline silicon provided on a semiconductor substrate is single-crystallized by using a part of the substrate as a seed, and prior to depositing silicon, the semiconductor is placed in a reducing atmosphere. By irradiating the substrate with energy rays of short wavelength, the natural oxide film on the surface of the substrate is removed at low temperature without damaging other regions, which enables subsequent epitaxy.

[Conventional technology]

In order to realize a three-dimensional circuit device, a low temperature process that minimizes the effects of autodoping and solid phase diffusion is required in the process of stacking semiconductor layers in multiple layers. Among various methods that have been proposed in the past, there is a solid phase epitaxy method. This is because a part of the surface of the semiconductor substrate is opened to expose the surface of the underlying crystal, and a non-crystalline or polycrystalline silicon film is deposited thereon, and then solid phase epitaxy is performed using the underlying crystal of the opening as a seed. This is a technique for making the whole into a single crystal. Since a single crystal can be obtained by low-temperature treatment at 550 ° C to 650 ° C, it is said to be an effective means for manufacturing a three-dimensional circuit element.

When performing solid phase epitaxy, it is usually necessary to remove a thin native oxide film formed on the surface of the opening when the opening is formed. This is because the presence of the natural oxide film deteriorates the contact state between the polycrystalline silicon and the substrate opening and hinders the progress of epitaxy.

Conventionally, in order to remove this natural oxide film, after depositing amorphous or polycrystalline silicon, the temperature is raised to about 1000 ° C. and annealing is performed in an H ₂ atmosphere. Cleaning by sputtering (for example, Nikkei Micro Devices, October 1985, P79-87) or etching in hydrogen plasma has been performed.
When using the MBE apparatus, the natural oxide film was removed by baking at about 600 ° C. in an H ₂ atmosphere before depositing silicon.

[Problems to be solved by the invention]

However, these methods have problems that they cause re-diffusion of impurities during high-temperature processing and that the substrate and element regions are damaged by the impact of ions during sputtering or plasma etching. Further, in the case of the MBE device, there is a problem that the device itself is expensive and is not suitable for mass production.

[Means for solving problems]

The present invention irradiates a pulse of a short wavelength energy ray on a semiconductor substrate by an excimer laser or the like in a reducing atmosphere prior to depositing amorphous silicon or polycrystalline silicon, so that other regions can be irradiated at low temperature. The natural oxide film on the substrate surface is easily removed without damage.

[Action]

When the semiconductor substrate is irradiated with a pulse of a short-wavelength energy ray, only the natural oxide film on the substrate surface is instantly heated, and the natural oxide film is removed without thermally affecting other regions.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the concept of the present invention. As shown in FIG. 1A,
After the sample having the opening formed in the insulating film (2) on the single crystal silicon substrate (1) is washed, a thin natural oxide film (3) of about 10 Å is attached to the surface of the opening. Then the sample
It is introduced into a device such as a CVD device where amorphous or polycrystalline silicon is to be deposited, and exposed to a hydrogen atmosphere of several hundred Torr.

Next, a short wavelength (λ <33
A light beam pulse (4) having a uniform energy distribution (0 nm) and a short time (τ <10 ⁻⁶ sec) is irradiated. In this way, only the portion of the opening near the surface (<1000Å) is heated, and the native oxide film (3) is removed without damaging the underlying silicon.

Subsequently, an amorphous or polycrystalline silicon film (5) is deposited on the substrate (1) in the same device (<650 ° C.). Amorphization is performed by implanting Si ⁺ ions as needed (FIG. 1B).

After that, annealing (<<
650 ° C), solid phase epitaxy proceeds from the opening,
The entire amorphous or polycrystalline silicon film (5) is single crystallized to obtain a single crystal layer (6). (FIG. 1C).

FIG. 2 shows an embodiment in which the method of the present invention is applied to the manufacture of a three-dimensional circuit device. In this example, the circuit is composed of MOS transistors, but other variations such as bipolar transistors may be considered.

First, as shown in FIG. 2A, after the first MOS transistor (7) is provided on the silicon substrate (1) by a usual method, an opening (8) is formed at an appropriate position of the field oxide film (2). Form. Subsequently, as shown in FIG. 2B, a thick insulating film (9) serving as an interlayer insulating film is provided on the entire surface of the substrate. This insulating film (9) also has a function of correcting irregularities on the surface and flattening the surface to prepare for formation of the upper layer.

Next, the insulating film on the opening (8) provided previously is removed to expose the substrate surface. After the cleaning process, the surface of the opening (8) is covered with the natural oxide film (3) as in FIG. 1B (FIG. 2C).

Here, a light beam pulse (4) having a short wavelength is irradiated under the same conditions as in the previous example to remove the native oxide film (3). Subsequently, an amorphous or polycrystalline silicon layer (5) is deposited (FIG. 2D) and subjected to low temperature annealing, solid phase epitaxy proceeds to obtain a single crystal upper layer (6) (FIG. 2E). ).

Thereafter, a second MOS transistor (10) is formed on the upper layer (6) by a usual method, whereby a three-dimensional circuit element having a double structure can be constructed (FIG. 2F).

〔The invention's effect〕

As described above, according to the present invention, by irradiating short-wavelength pulsed light in a reducing atmosphere, the natural oxidation of the opening can be effectively performed at low temperature (<600 ° C.) without damaging the underlayer. The film can be removed. When this method is used, the influence of the substrate and the underlying layer on the element region is suppressed to a minimum, and therefore it is suitable for manufacturing a three-dimensional circuit element that requires a process of stacking semiconductor layers on which elements are formed. Furthermore, the device itself only needs to be provided with a window for introducing energy rays into a conventionally used device such as a conventional CVD device, and since it does not require difficult work, it has the advantage of being easy to interface with the conventional device. There is also.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A to 1C are sectional views showing the concept of the method of the present invention, and FIG.
FIGS. 7A to 7F are sectional views of process steps showing an example of manufacturing a three-dimensional circuit device according to the method of the present invention. (1) is a silicon substrate, (2) is a field oxide film,
(3) is a natural oxide film, (4) is an energy beam,
(5) is a polysilicon layer, (6) is a single crystal layer, (7) is a first MOS transistor, (8) is an opening portion, (9) is an interlayer insulating film, (10) is a second MOS transistor, ( 11) is a field oxide film.

Claims (1)

[Claims] 1. A semiconductor layer is formed on the insulating layer through a semiconductor element formed on the semiconductor substrate and an opening formed on the semiconductor substrate in an insulating layer formed to cover the semiconductor substrate. In the method for manufacturing a semiconductor device according to claim 1, after forming the opening, the amorphous or polycrystalline semiconductor is introduced into a device to be deposited, and the opening is exposed in a reduced pressure reducing atmosphere on the surface of the semiconductor substrate. A method of manufacturing a semiconductor device, wherein the surface of the semiconductor substrate is etched by irradiating a pulse of an energy ray having a short wavelength, and then an amorphous or polycrystalline semiconductor is deposited at 650 ° C. or lower.