JPS59123245A - Crystal substrate for semiconductor device - Google Patents

Abstract

PURPOSE:To enable to form a magnesia single crystal film having an excellent crystallizing property by a method wherein a thin film of magnesia spinel single crystal is grown on a silicon single crystal substrate and a single crystal film of magnesia is formed on the thin film. CONSTITUTION:An aluminum 2 and a magnesium chloride 3 are installed in the raw material chamber 1 of a reaction tube, and hydrogen chloride gas is introduced into from a gas lead-in port 4 for producing AlCl3 gas and the produced gas is transported to a growing chamber 6 along with MgCl2 gas by nitrogen gas introduced into from the lead-in ports 4 and 5. Nitrogen gas, carbon-dioxide gas and hydrogen gas are transported to the growing chamber 6 from a gas lead-in port 7 and a single crystal film of magnesia spinel is grown on a silicon single crystal substrate 9 which is mounted on a substrate holder 8. MgCl2 gas only is transported to the growing chamber 6 from the raw material chamber 1 without intorducing HCl gas into and a single crystal film of magnesia is grown on an MgO-Al2O3 single crystal film. As a result, the titled low-cost and high- quality crystal substrate for attaining the complete separation of elements can be obtained.

Description

[Detailed description of the invention] The present invention relates to a crystal substrate useful for semiconductor devices.

Various methods of insulating and separating elements have been attempted in order to increase the density and speed of operation of semiconductor integrated circuits. SO8 (Silicon on Apphires) is produced by growing a silicon single crystal film on a sapphire single crystal substrate.
e) is well known as a typical example. However, in SO8, the sapphire single crystal substrate is expensive, and the large difference in crystal structure and lattice constant between silicon and sapphire causes a high density of defects to occur in the silicon single crystal film, making it difficult to achieve the desired electrical characteristics. There are disadvantages such as not being able to obtain

As a method to improve these shortcomings of SO8, insulator single crystals such as sapphire, magnesia alsinate spinel Mho-Allqoz (hereinafter referred to as magnesia spinel), and magnesium oxide MyO (hereinafter referred to as magnesia) are deposited on a silicon single crystal substrate. Attempts have been made to grow a film by a vapor phase epitaxial method, and then grow a semiconductor single crystal film of silicon, gallium arsenide, etc. thereon. Since this method uses a silicon single crystal substrate, it is possible to obtain a silicon active layer of high quality at low cost. However, it is difficult to grow a high-quality insulating single crystal film on a silicon single crystal substrate, and as a result, the crystallinity of the semiconductor single crystal film grown thereon is not improved either, which remains a problem. In particular, in the case of sapphire (α-Al, o,), the lattice constant mismatch with silicon is about 15%, which is very large.In addition, the phase transformation to gamma alumina (γ-A11 qOs) is easy, making it a good quality sapphire. It is difficult to obtain single crystal films with good reproducibility. Mag sand shear spinel has the same cubic crystal shape as silicon, and its lattice constant of 8.08A is doubled to 16.16A, which is 16.29, which is three times the lattice constant of silicon, 5.43A.
There is a lattice constant mismatch with A of about 0.8%, and a single crystal film with good crystallinity can be obtained with sapphire.

On the other hand, magnesia is also cubic, but its lattice constant is 4.213A, and the lattice constant mismatch between 16.852A, which is four times this, and 16.29A, which is three times the lattice constant of silicon, is 33%. Magnesia Spinel, you're bad. As a result, crystallinity is generally poorer than that of magnesia spinel. The object of the present invention is to form a magnesia single crystal film with good crystallinity. As a result of intensive research into a technique for forming a magnesia single crystal film using a vapor phase growth method, the inventors of the present invention have grown a thin film of magnesia spinel single crystal on a silicon single crystal substrate, and formed a magnesia single crystal film on top of the thin film. We have discovered that a magnesia single crystal film with better crystallinity than magnesia spinel can be obtained and that a single crystal film of semiconductors such as silicon and gallium arsenide with good crystallinity can be formed on this magnesia single crystal film.

The present invention is based on the above discovery, and is based on the representative composition formula Ml'0-Aj? on a silicon single crystal substrate. A crystal substrate for a semiconductor device, characterized in that a single crystal film of magnesia spinel represented by , O, is formed, and a single crystal film of magnesium oxide is formed on the magnesia spinel.
And silicon dioxide is formed on the silicon single crystal substrate, and Mg0-A# as a representative composition formula is formed on the silicon dioxide.
,0. A crystal substrate for a semiconductor device, characterized in that a single crystal film of magnesia spinel is formed on the magnesia spinel, and a single crystal film of magnesium oxide is formed on the magnesia spinel, and a silicon single crystal substrate is typically used. A single crystal film of magnesia spinel whose composition formula is M 90-AJ t Os is formed, a single crystal film of magnesium oxide is formed on the magnesia spinel, and a single crystal silicon film is further formed on the magnesium oxide. A crystal substrate for a semiconductor device, characterized in that silicon dioxide is formed on a silicon single crystal substrate, and a representative composition formula of MqO-A et al. 03 is formed on the silicon dioxide.
A single crystal film of magnesia spinel represented by is formed, a single crystal film of magnesium oxide is formed on the magnesia spinel, and one or more elements selected from Group 1 of the periodic table are further formed on the magnesium oxide. The present invention provides a crystal substrate for a semiconductor device, characterized in that a compound semiconductor single crystal film made of one or more elements selected from group (1) and (3) is formed.

Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 A magnesia spinel single crystal film, a magnesia single crystal film, and a silicon single crystal film were sequentially formed on a silicon single crystal substrate with a plane orientation (100). FIG. 1 is a schematic cross-sectional view of a reaction tube of a vapor phase growth apparatus in which magnesia spinel and magnesia single crystal films were grown.

First, a magnesia spinel single crystal film was grown on a silicon single crystal substrate, and aluminum A was placed in the raw material chamber 1 of the reaction tube.
ll2 and magnesium chloride MfC/2,3 were installed, and the respective temperatures were set to 600°C and 950°C. Hydrogen chloride gas is introduced from the gas inlet 4, and AAIC18 gas is generated by the reaction Al + HC6 - bow 6C63, and 950
The mercury C6 evaporated at 0.degree. C. was transported to the growth chamber 6 by nitrogen gas introduced from the inlet 4.degree. On the other hand, along with nitrogen gas, carbon dioxide gas CO and hydrogen gas H2 were fed into the growth chamber from the gas introduction lower.

The gases are mixed in the growth chamber, and a single crystal film of magnesia spinel is produced on the silicon single crystal substrate mounted on the substrate holder 8. The reaction at this time is thought to be as follows.

MQCl, + 2An(J3-!-4CO, + 4.H
, -+ Mg0-Al, 03+CO+8HC6 (1) The growth temperature was 980°C and the growth was performed at a growth rate of 045 μm/hr.

Next, a magnesia single crystal film was grown on the M2OAlqOs single crystal film, but this was done using the reaction tube shown in Figure 1, without introducing the HCI gas that was introduced from the gas inlet in the case of magnesia spinel growth. Only M'iC4 and gas were transported from the raw material chamber to the growth chamber. By keeping the other conditions the same as those for growing magnesia spinel, it was possible to grow a single crystal film of MgO. Figure 2 shows the film thickness o, 4
In the diffraction pattern of X-ray powder diffraction when magnesia with a film thickness of 0.4 μm is grown on a magnesia spinel with a thickness of 5 μm, Mgo Al*Os at 45° in 20, adjacent to the (400) peak, ) There was a strong diffraction peak, and no diffraction in directions other than the (100) direction was observed.

Figure 3 shows when ~0.2 pm of magnesia Mgo is grown on magnesia spinel with a film thickness of 4ooX (7) MgO (
200>Diffraction X-ray rocking curve whose half width is 2
It was 900 seconds. However, the magnesia spinel single crystal film alone has a thickness of 0.2 pm (D film thickness: 404,620 g (
400) The half width of diffraction was about 4500 seconds. Generally, the crystallinity of a single crystal film can be evaluated by the half-width of X-ray rocking diffraction, and it is said that the smaller the half-width, the better the crystallinity.

The half-value width depends on the thickness of the single crystal film, and the smaller the film thickness, the larger the half-value width becomes. Therefore, from the above results, it can be said that the magnesia single crystal film grown on the magnesia asbinel single crystal film has significantly better crystallinity than magnesia spinel.

In this example, a silicon single crystal film was grown on a magnesia single crystal film formed as in the previous example by a thermal decomposition method of silane SiH4. 3 at a growth temperature of 1020°C.
After growing silicon of μrn, the half-width was measured from the Xw rocking curve of the asymmetric reflection of (422) diffraction, and the result was about 450 seconds. This crystallinity exceeds that of SO8.

Example 2 Amorphous silicon dioxide 5in2 was formed by thermal oxidation at the interface between a silicon single crystal substrate and a magnesia spinel single crystal film, and rMgo single crystal ji/M90Al, Os single crystal film/
A crystal substrate having a configuration of "Sin,/silicon single crystal substrate" was created.

The present inventor has already formed a magnesia spinel single crystal film on a silicon single crystal substrate, and then thermally oxidizes the silicon single crystal through the magnesia spinel single crystal film by annealing in a thermally oxidizing atmosphere, and the magnesia spinel and silicon single crystal It has been proposed that Sin can be formed at the boundary of the substrate, thereby significantly improving the electrical properties of the insulating layer. In this example, after forming Sin, a magnesia single crystal film is formed on a magnesia spinel single crystal film. After producing a film of magnesia spinel with a thickness of 400A using the same method as in Example 1, the film was heated at 1100°C.
Steam oxidation was performed to form about 500 OA of Sin at the boundary between magnesia spinel and silicon.

Thereafter, a single crystal film with a J film thickness of 02 μm was formed under the same conditions as in Example 1. As a result, the (200) diffraction of magnesia was
The half width of the 40-king curve was 2800 seconds.

Example 3 rMqO single crystal prepared in Example 2/M q O・A
11qOs single crystal film/Sio2/Si single crystal substrate"Gallium arsenide G a A
A single crystal film of s was grown. A single crystal film of GaAs is produced by metal organic vapor phase epitaxy (MO.
grown by CVD).

The growth was performed by thermally decomposing trimethylgallium and arsine on a substrate heated to 720°C in a high-frequency heating furnace using hydrogen gas as a carrier gas. As a result, a GaAs single crystal film of poor quality with a mirror surface was grown.

In this example, in addition to GaAs, GaAlAs, G
A single crystal film of a ■-■ compound such as aP can be grown.

The invention has been explained above with reference to embodiments. However, separating the elements of a semiconductor integrated circuit with an insulator is extremely important for achieving high integration and speeding up the operation of the elements. The present invention provides an inexpensive, flat-quality crystal substrate for a semiconductor device that achieves complete isolation of elements by means of an insulating single crystal film formed on the substrate, and has great industrial value.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a vapor phase growth apparatus for magnesia spinel and magnesia single crystal films used in Examples. FIG. 2 shows the powder X-ray diffraction ζ-turn of a sample in which magnesia spinel and magnesia single crystal films are laminated on a silicon single crystal substrate with a plane orientation of (100). Figure 3 is a diagram showing the X-ray diffraction rocking curve of the (20OE plane) of the magnesia single crystal film. 1- Raw material chamber, 2... Aluminum, 3... Magnesium chloride, 4, 5.7... Gas introduction Tube, 6...Growth chamber, 8...Substrate holder, 9...Crystal substrate.

Claims (1)

[Claims] 1. MqO as a representative compositional formula on a silicon single crystal substrate
-Al, 0. 1. A crystal substrate for a semiconductor device, characterized in that a single crystal film of magnesia spinel represented by: is formed, and a single crystal film of magnesium oxide is formed on the magnesia spinel. 2. Silicon dioxide is formed on a silicon single crystal substrate, and Mg0-A as a representative composition formula is formed on the silicon dioxide.
1. A crystal substrate for a semiconductor device, characterized in that a single crystal film of magnesia spinel represented by n, 0, is formed, and a single crystal film of magnesium oxide is formed on the magnesia spinel. 3. MgO as a representative composition formula on a silicon single crystal substrate
,-A#20. A semiconductor characterized in that a single crystal film of magnesia spinel is formed, a single crystal film of magnesium oxide is formed on the magnesia spinel, and a single crystal film of silicon is further formed on the magnesium oxide. Crystal substrate for equipment. 4. Silicon dioxide is formed on a silicon single crystal substrate, and M2O-A is formed on the silicon dioxide as a representative compositional formula.
6.0. A single crystal film of magnesia spinel represented by is formed, a single crystal film of magnesium oxide is formed on the magnesia spinel, and one or more elements selected from Group Ⅰ of the periodic table are further formed on the magnesium oxide. A crystal substrate for a semiconductor device, characterized by forming a compound semiconductor single crystal film consisting of one or more elements selected from group (1) and one or more elements selected from group (2). .