JPH03188618A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a silicon-on-insulator(SIO) substrate which is made of single crystallized silicon layer and has a good crystallinity by converting a polycrystalline silicon layer of large crystal gains converted by heat-treatment into a single crystalline silicon layer by irradiating the polycrystalline silicon layer with an energetic beam. CONSTITUTION:When an amorphous silicon layer or an amorphous silicon layer containing silicon crystals is formed on an substrate having an insulating layer on the surface and the layer is heat-treated, the layer is converted to a polycrystalline silicon layer of large crystal grains. When the layer is irradiated with an energetic beam, the polycrystalline silicon layer of large crystal grains is more excellently converted into a single crystalline layer than a polycrystalline silicon layer of small crystal grains which disturb excellent single crystallization. As a result, an SOI substrate for semiconductor which is made of a single crystallized silicon layer and has a good crystallinity is produced in a short time.

Description

[Detailed Description of the Invention] [Summary] Regarding a method for manufacturing a semiconductor device using a Sol substrate, it is possible to obtain a Sol substrate with good crystallinity of a single crystal silicon layer for forming a semiconductor element in a short time. Most of the above is removed by forming a silicon layer made of amorphous silicon or amorphous silicon containing silicon crystals on a substrate having an insulating layer on the surface, and then heat-treating the whole. converting a silicon layer that is amorphous silicon into a polycrystalline silicon layer with large crystal grains; and then converting the polycrystalline silicon layer into a single crystal silicon layer by irradiating the polycrystalline silicon layer with an energy beam. Configure it like this.

[Industrial application field]

The present invention is based on Sol (silicon on 1n
The present invention relates to a method of manufacturing a semiconductor device using a sulator substrate.

Currently, one way to increase the speed or density of semiconductor devices is to create a three-dimensional structure, and various techniques are being developed to realize this.

In order to realize this three-dimensional structure semiconductor device, a Sol substrate having a silicon layer on which elements can be formed on an insulating layer is essential.

Normally, to obtain a Sol substrate, polycrystalline silicon deposited on an insulating layer is recrystallized, that is, made into a single crystal, by irradiating it with a laser beam. Since it contains many grain boundaries, the desired semiconductor device cannot be manufactured unless these are reduced.

[Prior Art] When manufacturing an SOI substrate using a conventional technique, chemical vapor deposition is applied to the entire surface of an insulating layer made of silicon dioxide formed on a silicon substrate.
apour deposit.

A polycrystalline silicon layer is deposited by a CVD method, and the polycrystalline silicon layer is irradiated with an energy beam, such as a laser beam, focused to a diameter of about 10 [μm]. At that time, the laser beam is irradiated so that the edges of the irradiation area overlap, and the melting and
Recrystallization is performed so that the polycrystalline silicon layer on the insulating film has a single crystal region with an area sufficient to form a semiconductor element.

[Problem to be solved by the invention]

When polycrystalline silicon is single-crystallized using the above-mentioned conventional technology, good single-crystalization can be achieved because the polycrystalline silicon crystal grains that serve as seed crystals during recrystallization are small. However, when semiconductor devices are formed, deterioration of electrical properties such as leakage characteristics due to crystal defects is likely to occur (because of the large amount of grain boundaries within the wafer). Due to the poor uniformity of the crystals used in semiconductor devices, their characteristics currently do not reach the level of semiconductor devices using bulk silicon.Furthermore, a large area is scanned with a narrowly focused energy beam. , the time required for recrystallization is long, and its throughput is approximately 3
It will only be about [sheets/hour].

The present invention aims to make it possible to obtain a Sol substrate with good crystallinity of a single crystal silicon layer for forming a semiconductor element in a short time.

[Means to solve the problem]

The above-mentioned problem was solved by using a polycrystalline silicon layer with large crystal grains to be made into a single crystal, and by using an energy beam with a large beam diameter and low energy per unit area. This can be solved by irradiating both at once. At this time, since there is no need for melting and recrystallization, the substrate may not be heated.

A polycrystalline silicon layer with large crystal grains can be obtained by forming an amorphous silicon layer or an amorphous silicon layer containing silicon crystals by PTA (rapid thermal aeration).
This can be obtained by applying the nneal method, the furnace annealing method, or the like. Additionally, a beam expander may be used to generate an energy beam with a large beam diameter.

For this reason, in the method for manufacturing a semiconductor device according to the present invention, a substrate (for example, a silicon half 11+&I
) to form a silicon layer (e.g. silicon layer 3) made of amorphous silicon or amorphous silicon containing silicon crystals, and then heat-treating the entire silicon to form a silicon layer that is mostly amorphous silicon. converting the layer into a polycrystalline silicon if (e.g. polycrystalline silicon layer 3') with large grains and then converting the polycrystalline silicon layer into a monocrystalline silicon layer (e.g. monocrystalline silicon) by energy beam irradiation. the silicon layer 3'').

[Effect]

By adopting the above method, it is possible to manufacture a Sol substrate having a single crystal silicon layer with good crystallinity in a short time, and since the substrate is not heated to high temperatures, a low temperature process can be realized. In particular, in semiconductor devices with a three-dimensional structure, it is possible to form an upper single-crystal silicon layer without adversely affecting the underlying elements, making it possible to obtain devices with good characteristics. can.

〔Example〕

1 to 4 are cross-sectional side views of essential parts of a semiconductor device at key points in the process for explaining one embodiment of the present invention, and the following description will be made with reference to each figure.

See Figure 1 1-(1) By applying a thermal oxidation method, silicon semiconductor substrate 1
An insulating film 2 made of silicon dioxide and having a thickness of about 1 μm, for example, is formed thereon.

See Figure 2 2-(1) Low pressure vapor phase growth
cal vapor deposition:L
By applying the PCVD method, the thickness of
Silicon j!3 made of amorphous silicon or amorphous silicon containing silicon crystals is deposited at a temperature of about 400 ("C) to 550 ("C).

See FIG. 3 3-(1) The wafer is placed in a furnace and annealed at a temperature of about 600 ('C) for 2 hours.

After this process, the silicon layer 3 has a diameter of 2 [μm] to
This is converted into a polycrystalline silicon layer 3' consisting of large crystal grains of about 3 [μm].

See Figure 4 4-(1) By irradiating the laser beam 4 and making the crystal grains in the silicon layer 3' larger, the single crystal silicon layer 31
Convert to

At this time, the diameter of the laser beam is first expanded from about 20 (mm) to 30 (mm) using a beam expander, and the laser beam is spread on the wafer according to the chip size. For example, it is best to condense the light to about f2 [kaku] to f3 [kaku] and irradiate it.

In this way, the energy per unit area in the laser beam is lower than in the case of normal laser beam annealing, and the silicon layer 3' can go through the process of reaching a temperature at which it completely melts. The silicon layer 3# is single-crystalized and becomes a single-crystal silicon layer 3#.

The main conditions for this laser beam irradiation are listed below.

Power output 200-300 (mW) (measured with a power meter) Beam diameter: 2-3 [Peng] (variable) Beam scanning speed: 150 (mm/sec) (carried out on an X-Y stage) Figure 5 shows the laser・Represents an explanatory diagram of the main parts of the laser beam irradiation device to explain the process of irradiating the beam.

In the figure, 5 has wavelengths of 488 (nm) and 514.5
(nm) argon laser, 6 is shutter, 7
is an external wave plate, 8 is a polarizing beam splitter, 9 and 10
is a total reflection mirror, 11 is a semi-transparent mirror with a transmittance of 99%, 12 is a power meter, and 13 is a laser beam.
Expander, 14 is a gicroic mirror, 15 is a condensing lens, 16 is a wafer, 17 is an X-Y stage, 1
8 is a microscope, 19 is a semi-transparent mirror, 20 is a sodium
A light source consisting of a lamp is shown, and a total reflection mirror 22 represents an eye.

In the illustrated laser beam irradiation device, the A wavelength plate 7 serves to correct the polarization angle of the laser beam from the argon laser 5. In other words, even if the laser 5 is not limited to argon, even if it is placed as specified, it does not necessarily emit light that is polarized at a predetermined angle, such as vertically or horizontally, and may be slightly deviated. In some cases, it is not possible to make the light incident on the polarizing beam splitter 8 as it is. Therefore, the η wavelength plate 7 is used to perform the correction. The semi-transparent mirror 11 has, for example, 10
Of the laser beam (W), 10100 ( ) is reflected and sent to the power meter 12, which converts the laser beam into an electric current using a built-in silicon photocell and measures the electric current. The power of the laser beam is known in the following.Laser Beam Expander 13
serves to expand the diameter of the laser beam. The dichroic ink mirror 14 completely reflects the laser beam from the laser beam expander I3 and irradiates the wafer 16 through the condensing lens 15, and also completely reflects the laser beam from the wafer 16. The light tA2, which is a sodium lamp in the microscope 18, has the function of being able to reflect back to the direction of the laser beam expander 13.
It has a function of completely transmitting the light from 0 to irradiate the wafer 16, and transmitting the returned light so that what is transmitted through the semi-transparent mirror 19 can be seen with the eyes 22. Therefore, the observer can work while observing the surface of the wafer 16 without damaging the eyes 22 by the laser beam.

By the way, when the present invention was carried out as described above, the diameter was about 10 (cm) (4 (inches)).
It was possible to process [sheets/hour]. Incidentally, when using the conventional technique, the number of layers was 3 [layers/hour] at most, and the crystallinity of the single crystal silicon layer was inferior to that according to the present invention.

〔Effect of the invention〕

The method for manufacturing a semiconductor device according to the present invention includes a step of forming a silicon layer made of amorphous silicon or amorphous silicon containing silicon crystals on a substrate having an insulating layer on its surface, and then heat-treating the whole. converting the largely amorphous silicon layer into a polycrystalline silicon layer with large grains by irradiating the polycrystalline silicon layer with an energy beam to form a monocrystalline silicon layer; The process includes a step of converting into.

By adopting the above configuration, it is possible to manufacture a Sol substrate having a single crystal silicon layer with good crystallinity in a short time, and since the substrate is not heated to high temperatures, a low temperature process can be realized. In particular, in semiconductor devices with a three-dimensional structure, it is possible to form an upper single-crystal silicon layer without adversely affecting the underlying elements, making it possible to obtain devices with good characteristics. can.

[Brief explanation of drawings]

1 to 4 are cross-sectional side views of essential parts of a semiconductor device at key points in the process for explaining one embodiment of the present invention, and FIG. 5 is a laser beam irradiation process for explaining the laser beam irradiation process.・Represents an explanatory diagram of the main parts of the beam irradiation device. In the figure, 1 is a silicon semiconductor substrate, 2 is an insulating film made of silicon dioxide, 3 is a silicon layer made of amorphous silicon or amorphous silicon containing silicon crystals, 3' is a polycrystalline silicon layer, and 3'' is a single silicon layer. 4 is a laser beam, 5 is a crystallized silicon layer with a wavelength of 488 (
6 is a shutter, 7 is an external wave plate, 8 is a polarizing beam splinter, 9 and 10 are total reflection mirrors, and 11 is a mirror with a transmittance of 99%. Transparent mirror 12 is a power meter, 1
3 is a laser beam expander, 14 is a dichroic mirror, 15 is a condenser lens, 16 is a wafer, 17
18 is an X-Y stage, 18 is a microscope, 19 is a semi-transparent mirror, 20 is a light source consisting of a sodium lamp, and 21 is a total reflection mirror 22, which represents an eye.

Claims (1)

[Claims] A step of forming a silicon layer made of amorphous silicon or amorphous silicon containing silicon crystals on a substrate having an insulating layer on the surface, and then heat-treating the whole to remove most of the silicon layer. converting the silicon layer, which is amorphous silicon, into a polycrystalline silicon layer with large grains; and then converting the polycrystalline silicon layer into a monocrystalline silicon layer by irradiating the polycrystalline silicon layer with an energy beam. A method for manufacturing a semiconductor device, characterized in that: