JPS60178620A - Manufacture of semiconductor substrate - Google Patents

Abstract

PURPOSE:To obtain an silicon-on-insulator having a large area by forming the triple structure of magnesia spinel-SiO2-silicon, using an opening section in the structure as a seed and depositing a single crystal silicon film on the whole surface of a wafer in a homoepitaxial manner. CONSTITUTION:An epitaxial film 11 consisting of MgO.Al2O3 is grown on an Si single crystal substrate 10. When a wafer is thermally oxidized, oxygen diffuses to silicon through magnesia spinel, and SiO2 is formed between magnesia spinel and silicon. A striped pattern is formed to the wafer having obtained triple structure of magnesia spinel-SiO2-silicon. The wafer is charged to an epitaxial growth device, and silicon is deposited. Silicon is not deposited on magnesia spinel because a source gas SiH2Cl2 contains Cl at that time. The film 11 is grown selectively in an epitaxial manner while using silicon in opening sections as seeds. The whole surface is coated with a single crystal 13 in which there is no micro-twin of silicon.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention describes a method of growing a silicon epitaxial film in a vapor phase on a single crystal silicon substrate having an insulating film pattern on its surface.

Integrated circuits that use a single crystal thin film on an insulating substrate as an active layer are suitable for higher density, higher speed, and higher voltage resistance because elements can be easily separated and parasitic capacitance can be reduced. . As a method for forming a single crystal film on an insulating substrate,
A method of forming a single crystal semiconductor film on a single crystal insulating substrate such as silicon on sapphire or silicon on spinel, or depositing polycrystalline or amorphous silicon on an amorphous insulating substrate and using a heat source such as a laser. There is a method of recrystallizing from 9 to 7 yl, I. Among these methods, in the heteroepitaxial method, lattice defects such as microtwins occur due to lattice misalignment between the substrate and silicon film, and therefore the mobility in the silicon film is smaller than the value of the mobility in bulk silicon. There are five drawbacks. Furthermore, it is difficult to form a large-area single crystal film using the recrystallization method, and practical application is still far away.

Although limited to cases where seeds can be used, a silicon single crystal film on an insulator can also be obtained by silicon vapor phase epitaxy.

However, this method (Evitaxial Lateral Overgrowth: ELO) cannot prevent silicon fine particles from precipitating on the insulating film when grown under normal epitaxial growth conditions. In order to prevent this, in the method of repeating deposition and gas etching, the ratio of the growth rate in the direction parallel to the wafer surface to the growth rate in the direction perpendicular to the wafer surface is approximately 1:1, and the silicon-on-in-shell film is deposited over a wide area. In order to form a shrimp-grown silicon film, the thickness of the shrimp-grown silicon film inevitably becomes thicker.

Further, in a method in which hydrochloric acid gas is introduced during growth and silicon is not deposited on the Z insulator, facets develop as the growth progresses, making it impossible to obtain a wide silicon oxide layer.

The present invention solves the problems with the vapor phase growth method using such seeds, and also provides a So-grown silicon film made of a shrimp-grown silicon film that has better crystallinity than the epitaxial growth method or the recrystallization method.
The present invention provides a method for manufacturing a 1-substrate.

That is, a magnesia@spinel epitaxial film is formed on a silicon single crystal, and then the silicon single crystal is oxidized through the magnesia-spinel film by a thermal oxidation method to form magnesia spinel:SiO.

: Form a silicon triple structure, then apply magnesium vapor and pattern 5ly2 to form a silicon single crystal opening, and homoepitaxially deposit a single crystal silicon film over the entire wafer surface using the opening as a seed. As a result, a large-area silicon-on-in-silicator is obtained.

Here, 810□ has a low dielectric constant and is easy to form, so it is inserted to increase the thickness of the insulator layer and reduce parasitic capacitance. In addition, with a silicon source gas containing Ct, the magnesia spinel film does not deposit silicon on it, and since the lattice mismatch with silicon is small, it does not interfere with overgrowth during lateral epitaxial growth. Kvt is set to take advantage of the fact that the growth rate in the direction of StO is faster than that of ELO.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Below, a method for manufacturing an SOI substrate according to an embodiment of the present invention will be described in detail.

Example Metallic magnesium and aluminum chloride are evaporated to form magnesium vapor and aluminum chloride vapor, respectively, which are transported by N2 gas, and mixed with oxygen gas separately transported by N2 gas. epitaxially grown. Figure 1 shows the vapor phase epitaxial apparatus used for this epitaxial growth.

The reaction tube is a double tube system with an outer tube of 80mm inner diameter and a 70mm inner diameter tube.
The inner tube is further separated into two chambers (3 and 4), and one part M3 is chlorinated at 7100°C, and the temperature of the metal magnesium in room 4 is set at 700°C.XI
First, N gas was flowed from the gas injection port 5 and the gas injection port 6 at a flow rate of 10 1 /min, respectively. On the other hand, N'A gas was flowed at a flow rate of 0.1 ce/ml n and nitrogen gas was flowed at a flow rate of 10 t/min from the gas injection lower.

The growth chamber 8 has a substrate holder 9 (10
0) Place the Sli single crystal substrate 10 and set its temperature to 95%.
The temperature was 0°C. As a result, approximately 1
An epitaxial film of MO11At203 was grown at a wavelength speed of 4 m/hr.

M when MO・At203 grows epitaxially
A high-quality epitaxial film 11 was grown without any reactions producing oeAz, o.

It was confirmed by X-ray diffraction double crystal method that the epitaxial film was oriented in the (100) direction, which matched the orientation of the 8i single crystal substrate. In this example, 0.00% oxygen gas is supplied from the gas inlet. Carbon dioxide CO□0 instead of IA/win. IL/
A similar #i pot was obtained even when mi mouth was supplied.

When the obtained wafer with a magnesia spinel-on-silicon structure of about 1 JWI is thermally oxidized, the ``w'' diffusion into the silicon through the magnesia spinel causes 810. to be formed between the magnesia spinel and the silicon. (( b
) Figure) DRY O, middle 1000'c? - oxidized for 10 hours to approximately 11' sI/) S L In order to reduce the main capacitance of No.
Since the dielectric constant of tO is small, it is preferable that the insulating layer of StO is thick. However, increasing the oxidation time increases cost, so S10. The thickness of is 0.5 μm-2p
A range of m is practical.

Magnesia spinel obtained by K in this way: StO,
: Silicon triple structure wow, -tc@i.

A striped pattern with a pitch of 100 μm was formed. (Figure (C)). In this example, a resist for a stopper was patterned using a conventional photolithography technique, and magnesia spinel and StO were simultaneously patterned using a single block batch etching process.

In addition to sputter etching, magnesia spinel is HC/
It is also possible to pattern StO by wet etching with an HF-based etching solution.

Patterned magnesia spinel: SIO.

: After the silicon wafer was cleaned by Galancon, it was charged into a vacuum cylinder type infrared heating type epitaxial growth apparatus, and the carrier gas H8 was 120 A/ml, the source gas SiH, (, /, was 500 ce/ml, and the growth temperature was 1080° C.). Silicon was deposited under a pressure of 50 TORH. At this time, the source gases SiH and C4 contain Ct, so silicon is not deposited on the magnesia spinel. Using the silicon in the opening as a seed, selective epitaxial growth is performed. Growth surface exceeds the 810. layer,
Lateral epitaxial growth in the in-plane direction began beyond the magnesia spinel surface. Since HCt was not added during growth, there was little facet development. Therefore, even if it is grown for a long time, the lateral epitaxial growth will not be stopped due to the development of facets.

Moreover, magnesia spinel becomes a heterogeneous substrate in a direction perpendicular to homoepitaxial growth, and does not suppress lateral epitaxial growth as much as in the case of S1.

Furthermore, when %SiH, C4 is used as a source gas, nuclei cannot be generated on the %magnesia spinel, so the reaction species that reach the magnesia spinel move on the magnesia spinel and the lateral epitaxial growth rate is expressed as t't(
Add r. In this way, when the growth rate in the direction perpendicular to the plane is 1, the growth rate in the in-plane direction is 11.
5, and in about 10 minutes the entire surface could be coated with single crystal 13 in which no silicon microtwins were observed. ((d)
figure).

In the above example, the thickness of the magnesia spinel epitaxial growth film was 0.1 μm. As the magnesia spinel epitaxial film becomes thicker, its smoothness decreases, so the lateral epitaxial growth rate slows down. If the thickness of the magnesia spinel film is too small, the magnesia spinel film becomes island-like and SiO2 is exposed, which slows down the lateral epitaxial growth rate. K, which makes the lateral epitaxial growth rate more than 10 times the growth rate in the direction perpendicular to the wafer surface, reduces the magnesia spinel film thickness to 0.
It is preferable to set it between 0.05μfP1 and 0.2μm.

When the magnesia spinel film thickness was 0.08 μm, the lateral epitaxial growth rate was approximately 15 times the growth rate in the direction perpendicular to the wave plane. In addition to sin and cz, source gases include SiH4+HCt, 5
iC4,5IHCt3, SiH, CL can also be used.

As described above, the present invention provides a substrate on which a silicon-on-insulator film can be formed by a vapor phase growth method, which has not been expected in the past, and has great industrial value.

[Brief explanation of the drawing]

Figure H1 is a schematic cross-sectional view showing an apparatus for epitaxial growth of magnesia spinel. Figure 2 (ml, (bl, (c)
1(di) is a schematic cross-sectional view for explaining the type of manufacturing process of the semiconductor substrate according to the present invention. 1... Outer tube of reaction tube, 2-... Inner tube of reaction tube, 3.4.・・・・・・Raw material room, 5.6.7・・・・・・
Gas injection port, 8...Growth chamber, 9...Substrate holder, lO...St single crystal substrate, 11.
...Magnesia spinel film, 12...5
totll1113...ELO single crystal silicon film.

Claims (1)

[Claims] A magnesia spinel epitaxial film is formed on a silicon single crystal, and then the silicon single crystal is oxidized through the magnesia spinel film by a thermal oxidation method to form a KStO film between the magnesia spinel film and silicon, and then magnesia spinel and SiO□ Turn the film to create an opening where the silicon single crystal is exposed, and use that opening as a seed.