JPS6052118B2 - Magnesia spinel vapor phase growth equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The chemical formula of the present invention is nMg0-Al2O3-, where n is Mg
This relates to an apparatus for manufacturing magnesia spinel, which is expressed as 1, which refers to the number of moles of O, and more specifically, it is a method for vapor phase growth of magnesia spinel in place of sapphire in semiconductor devices, which is generally referred to collectively as SOS (Sion Sapphire). It is related to the device.

505 has various attractive features and is attracting attention as a need for high-speed logic elements, etc. However, on the other hand, it has various problems and has not become mainstream in the current semiconductor industry.

The problems are as follows. (1) Higher cost than homosilicon epitaxial growth.

(2) The crystallinity of the silicon active layer is poor compared to homosilicon epitaxial growth.

In order to eliminate such drawbacks of 505, 200-3
The present inventors have developed a semiconductor device with a new structure (hereinafter referred to as improvement 505) in which a 2-5 μm sapphire single crystal film is formed on a 00 μm silicon substrate, and a silicon epitaxial active layer is formed on this sapphire single crystal. has already proposed.

When a thin sapphire layer is formed on such a thick silicon substrate, the crystal structure of the latter is regulated by the former and becomes similar to the latter. Therefore, the silicon epitaxial layer on the sapphire layer grows in a state similar to that when grown on a silicon substrate, and has good crystallinity. However, as a result of the research conducted by the present inventor, it was found that the following problems remain unsolved in the improvement 505.

First, lattice mismatch due to the difference between the crystal structure of silicon (cubic crystal) and the crystal structure of sapphire (trigonal crystal) inevitably deteriorates the crystallinity of the silicon epitaxial phase. Next, the coefficient of thermal expansion of silicon crystal (3.59×10
-6Crf1/℃) and the coefficient of thermal expansion of sapphire crystal (8
．． 40 x 10-6 cm/℃), the improved S
The crystallinity of the silicon active layer deteriorates during the OS manufacturing process.
Thirdly, cracks are likely to occur due to the difference in hardness 7 of silicon crystal and hardness 9 of sapphire crystal. Due to the above-mentioned difficulties, carrier mobility in this silicon epitaxial layer is low, and 60% is lower than in bulk silicon.
Or it only reaches 70%. Therefore, it has been found that the device characteristics of the improved SOS are not fully satisfactory and that there are still problems that require further improvement. It is known to use magnesia spinel crystal (RlMgO●Ae2O3), which is an insulating material having the same crystal structure as silicon, in place of sapphire in a general SOS device.

This magnesia spinel crystal (lattice constant a=8.080
There is a lattice constant mismatch between A) and silicon crystal (lattice constant a=5.430A). However, each (
100 planes), the twice the lattice spacing of the spinel crystal and the three times the lattice spacing of the silicon crystal are almost equal.
It is said that there is no lattice mismatch between the two crystals, and that a good silicon epitaxial crystal can be obtained. Furthermore, since the dielectric constant of magnesia spinel is 8 compared to 10 of sapphire crystal, the parasitic capacitance of the epitaxial thin film can be reduced. Use magnesia spinel like the one above. Even in general SOS, improved S
Although this is desirable for an OS, the problem lies in the manufacturing method.

Conventionally, magnesia spinel has been prepared by pulling a single crystal from a melt of a predetermined composition. However, Ae2
Since the melting point of O3 exceeds 2000°C, the above. The temperature of the melt increases, leading to evaporation of Mg. As a result, it is extremely difficult to control the composition of the melt. Therefore,
The present inventor filed a patent application for a vapor phase growth apparatus as illustrated in FIG. 1 with the aim of solving the above problem by growing magnesia spinel in a vapor phase instead of a liquid phase.

This device comprises: (a) a reaction tube 1 equipped with one or more HCe gas inlets 4; body 2
C1 (c) A' metal 6c placed inside the first hollow body
A second hollow body 2 having one end connected to either of the HCe gas inlets and the other end opening into the reaction tube.
b, (e) Mg metal 6b placed inside the second hollow body
The heating means 7b1 of the retainer 5b1 (to) Ae6c (to)
Mg heating means 7c1 (within the force reaction tube (a), the support base 9 of the base plate 10 disposed facing the respective openings of the first hollow body and the second hollow body; 1
A CO2 introduction pipe 14 is included which opens into the reaction tube (a) at any part from the openings of the hollow body and the second hollow body to the substrate support stand 9. The present inventor carried out vapor phase growth of magnesia spinel using the above apparatus, and found that Mg or A
It has been found that unless the flow rate of the HCe gas contacting the Ae is carefully controlled, there is a problem in that the Ae source is contaminated by Mg-containing vapor.

The inventor's experiments have revealed that in order to grow good magnesia spinel, it is necessary to heat the Mg source to a relatively high temperature of 600 to 900°C. As a result of such high-temperature heating, the aforementioned problem of contamination of the Al source with Mg-containing vapor occurred. Therefore, it is an object of the present invention to provide an apparatus for vapor phase growth of magnesia spinel in which the A' source is not contaminated by Mg-containing vapor.

The vapor phase growth apparatus according to the present invention includes (a) a reaction tube equipped with one or more HCl gas inlets, the low end of which is connected to any of the HCI gas inlets, and the other end of which is connected to the reaction tube (a); A first hollow body to be opened, and Ae disposed inside the first hollow body opening.
The retainer is a second hollow body whose knee end is connected to either of the HCl gas inlets and whose other end opens into the reaction tube (A), and the length e1 thereof is the length of the first hollow body opening. The inner diameter t is 1/1.5 to 1/2 times the diameter E2 (and/or)
1 is 3 to 4 times the inner diameter T2 of the first hollow body (mouth).
A hollow body, (e) a Mg retainer disposed inside the second hollow body, a heating means for Ae, and a heating means for Mg; (ch)
A substrate support stand disposed within the reaction tube A to face the respective openings of the first hollow body (mouth) and the second hollow body II, and (ri) a CO2 introduction pipe opening into the reaction tube A. It includes. Hereinafter, the apparatus according to the present invention will be explained based on the drawings.

FIG. 2 is a sectional view illustrating a specific example of the device according to the present invention, which is labeled with the same reference numerals as in FIG. This device has many advantages when used to replace sapphire with magnesia spinel in modified SOS.

However, this device can also be used to replace sapphire with magnesia spinel in conventional general SOS.
A small tube 2 is fixed in a quartz reaction tube 1.

The small tube 2 is divided into two parts by a partition wall 2a, an upper hollow body 2b as a second hollow body and a lower hollow body 2 as a first hollow body.
c is formed by the partition wall 2a. Each of the upper hollow bodies 2b1 and lower hollow bodies 2c has a semicircular cross section. Inside each of the upper hollow body 2b1 and the lower hollow body 2c is a plate 5.
b, 5c are placed.

The plate 5b is located in front of the plate 5c when viewed in the flow direction of the HCe gas. Magnesium (Mg) 6b and aluminum (A') 6c are placed as sources in the dishes 5b and 5c, respectively. Upper hollow body 2 where Mg is placed
The lower hollow body 2 in which A' is arranged for the length f1 of b
The length E2 of c is 1.5 to 2 times. E2 is 1.5
If it is less than e1, the prevention of Ae contamination described below will not be achieved. When E2 exceeds 2.0'1, prevention of A' contamination can be achieved, but the length of the reaction tube 1 becomes longer, which is disadvantageous. One end of the small tube 2 communicates with a hydrogen chloride tube 4 passing through the quartz reaction tube 1, and the other end is open into the reaction tube 1.

The partition wall 2a extends into the HC' gas introduction pipe 4, and divides the inside of the hydrogen chloride pipe 4 into two flow paths. He,
A carrier gas consisting of one or more of Ar, N2 gas and H2 gas can be flowed into the hydrogen chloride tube 4 together with HCI. The flow rates and gas types of the two divided flow paths can be made different from each other. In the illustrated example, an approximately double concentric tubular structure is formed between the region where the small tube 2 is placed and the reaction tube 1 . but,
It is not necessarily necessary to adopt a double concentric tube structure. Known heating means 7b, 7c connected to mutually independent energy supplies (not shown) supply the Mg source 6b and the Ae source 6.
It is provided around the reaction tube 1 so as to surround c.

Af is heated by the heating means 7b to a temperature convenient for reaction with hydrogen chloride, generally within the range of 500 to 700°C, preferably 500 to 600°C. HCe is kept at room temperature and comes into contact with heated Ae. Due to this contact, the following formula: Ae+3HCf-+AfCf3+11 no 2H2
It is conceivable that the following reaction (1) will occur. H.C.
Since some moisture present in e reacts with Ae to produce Ae2O3, the introduction of HCe does not oxidize the Si substrate and inhibit the growth of the A'203 single crystal. M
The g sauce 6b is heated to 600 to 90 g depending on the heating means 7c.
Heated to 0°C.

This Mg source 6b is brought into contact with HCe gas. This H
The Ce gas needs to flow through a different flow path from the HC' gas that contacts the Ae source 6c. That is, the Mg source 6b and the Ae source 6c are placed in different flow paths, and their contact reactions are carried out without being influenced by each other. Hydrogen chloride gas is generally kept at room temperature and is thought to react with Mg according to the following formula:

Therefore, it is considered that the second reaction gas consists of MgC'2 and sulfur. In order to generate a sufficient amount of MgC'2 vapor by the reaction, it is necessary to heat the Mg to a relatively high temperature of 600 DEG to 900 DEG C. By this A
'In order to prevent the risk of contaminating the source 6c with Mg-containing vapor, the lengths of the upper hollow body 2b and the lower hollow body 2c are determined by the relationship 12≧1.5e1.
As a result, Mg-containing vapor does not reach the Ae source 6c, thereby avoiding contamination. A carrier gas inlet 8 is provided at one end of the reaction tube 1 .

The carrier gas flowing from the inlet 8 initially passes through the upper hollow body 2b1.
Flows through the annular space around the lower hollow body 2c, and then Mg
It flows in the direction of the substrate 10 together with the reaction gases of Ae and Ae. A base 15 made of quartz is placed in a part of the space of the reaction tube 1.
A support base 9 made of SiCl coated carbon, MO or N sowing is fixed on top.

Three disk-shaped Si substrates 10 (hereinafter referred to as substrates 10) are supported on the support stand 9.

Known high-frequency heating means 11 are provided in the area of the substrate. Furthermore, the fitting cap 13 is attached to the outlet 1 of the reaction tube.
It is provided on the first side. Although the disc-shaped substrate 10 is supported by the support stand 9 by its flat surface, it may be supported by its periphery. Substrate 10 is a single crystal of magnesia spinel in the case of an SOS device, and is a single crystal of silicon in the case of an improved SOS device.

In this contact, the silicon substrate is heated between 950°C and 13°C.
It is heated to a temperature of 50°C, generally 1000°C to 1270°C. In addition, the magnesia spinel substrate is 1
It is heated to 000-1300°C. In either case, if the heating temperature falls below the lower limit, the epitaxial growth rate of magnesia spinel will be low, while if it exceeds the upper limit, undesirable reactions will occur between the mixed gases. The flat surface of the substrate 10 is preferably 111, 110, or 100, preferably 100.

When the substrate 10 is silicon, 1000 to 1
It is heated to 270°C. C through the wall of reaction tube 1
An O2 introduction pipe 14 opens into the inside of the pipe 1.

The CO2 introduction pipe 14 may extend to the vicinity of the substrate 10. The oxidation reaction by CO2 is as follows: -1 to 5ν! 1(2νJllVVl(μAV(
It is considered to be 1U1.

In the mixing step of A'Cl3, MgCf2 and CO2, the mixing of the three gas components does not necessarily have to occur simultaneously.

If CO2 and other components are mixed too slowly, the first reaction gas (
Afce3+H2) to the second reaction gas (MgCe2+H2
), and there is a risk of decomposition of metal A' or Mg depending on the case, such as a decrease in the temperature of these gases. From the viewpoint of growing NMgO-Al2O3 on the substrate immediately after generation, it is better to mix CO2 and other components slowly. The flow rates of the various gases mentioned above are 1 x 10-
3 to 1×10−1 m0eImin,. H in contact with Mg
Ce is 0-3 to 1×10-1m0e1min. sC
02 is expected to be two to three times the total flow rate of the HCe gas. Yes. Magnesia spinel has an n value of 0.1 to 3
．． It is most stable when it is 5.

In order to obtain magnesia spinel with such n value,
The flow rate of HCe in contact with A' is 0.1 to 1e1 min.
．． The flow rate of HC,e in contact with Mg is 0.5~1e1mi
Preferably, the flow rates of n1 and CO2 are two to three times the total flow rate of HCe. Aec'2 and MgCf2
The flow rate of the carrier gas for transporting the gas is 7Ch7!77! for the diameter of the reaction tube. In the case of 10'Imin~30'
Imin is desirable.

When magnesia spinel is grown on the substrate 10 using the above-described apparatus, the flow rates of the Aec'3 reaction gas and the MgCl2 reaction gas are kept at predetermined flow rates in order to prevent the A' source 6c from being contaminated with Mg. accurately maintained. Therefore, the generated magnesia spinel-Al2
Since the n value of O3-tρ can be controlled accurately and easily, the present invention has many advantages in the manufacturing method of semiconductor devices, especially in mass production. FIG. 3 shows a vapor phase growth apparatus for magnesia spinel according to another specific example of the present invention.

The difference between this device and the device shown in FIG. 2 is that instead of changing the lengths of the upper hollow body 2b and the lower hollow body 2c,
The inner diameter is changed according to the relationship t1=(3-4)×T2. This prevents the Af source 6c from being contaminated by Mg, similar to the device shown in FIG. 4t2 also prevents contamination of the Al source 6c, but the diameter of the reaction tube 1 increases, which is disadvantageous. In addition, T
l,t. are generally t1=20-257!, respectively. r!
N, t2=5 to 87 m. If a magnesia spinel single crystal is vapor-phase grown in the above-mentioned apparatus and then a silicon active layer is epitaxially grown in the same apparatus, the productivity of the improved SOS can be increased. Furthermore, since silicon is grown on a fresh magnesia spinel single crystal, this method is advantageous in terms of the crystallinity of silicon. In this method, the supply of HCe gas from the introduction pipe 4 is first stopped. For this purpose, H2 gas or He
, Ar, and N2 to replace the HCl gas. Further, the introduction of CO2 from the CO2 introduction pipe 14 is stopped, and H2 gas or one or more carrier gases of He, Ar, and N2 are introduced from the CO2 introduction pipe 14. H2 gas and H
A mixed gas with one or more of e, Ar', and N2 is supplied to pipes 4 and 1.
It may be introduced from 4. Then, the heating by the heating means 7 is stopped and the Mg. Prevent evaporation of l5Af. Meanwhile, the heating means 12 heats the substrate 10 to 1000 to 1100°C.
Heat to. Hce, AIC'3, due to the above carrier gas,
After continuing purging of Mgce2 etc. for about 5 to 12 minutes, by introducing SiH4 or SiCf4 from the inlet 8,
Si single crystals can be epitaxially grown on magnesia spinel. In the above description, a horizontal device has been described in conjunction with the drawings, but exactly the same effects can be achieved in a vertical device.

Further, although the present invention has been described with respect to a method for manufacturing an improved SOS, the present invention is not limited to improved SOS.
It can be applied to all fields in which a magnesia spinel single crystal film is epitaxially grown on a substrate.

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

Example 1 Device as shown in Fig. 2 (e1=300T1n, e2=500
Epitaxial growth of a magnesia spinel single crystal was carried out using wn).

Growth conditions are shown in Table 1.

One powder growth was continued under the above conditions to obtain a grown layer with a thickness of 3 microns.

X-ray diffraction and IM analysis show that this layer has an n value of 0.2 and is a magnesia spinel single crystal with a growth plane of 111.
Confirmed by composition analysis by A. The above growth is 20
The process was repeated several times, and growth could be performed using the same flow rate and other conditions in all cases.

No contamination of Ae metal by Mg was observed, and the n value of magnesia spinel was almost the same each time. It was the same.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the vapor phase growth apparatus according to the earlier application of the present application;
3 and 3 are cross-sectional views showing a specific example of a vapor phase growth apparatus according to the present invention. 1... Reaction tube, 2... Tube, 2b, 2c... Hollow part, 4... Hydrogen chloride tube, 5... Dish, 6b... Mg source, 6c... A' source, 7... Heating means, 8...
- Carrier gas inlet, 9... Substrate support stand, 10... Substrate, 11... Outlet, 12... Heating means, 13... Grinding cap, 14... CO2 introduction pipe.

Claims (1)

[Claims] 1(a) A reaction tube equipped with one or more HCl gas inlets;
(b) a first hollow body having one end connected to one of the HCl gas inlets and the other end opening into the reaction tube (a); (c) disposed inside the first hollow body (b); (d) a second hollow body having one end connected to one of the HCl gas inlets and the other end opening into the reaction tube (a), the length l_1 of which is The length l_2 of the first hollow body (b) is 1/1.5 to 1/2 times (and/or) the inner diameter t_1 is the inner diameter t_ of the first hollow body (b).
(e) a Mg retainer disposed inside the second hollow body (d); (f) the A;
(g) heating means for the Mg; (ch) facing the respective openings of the first hollow body (b) and the second hollow body (d) in the reaction tube (a); A single-crystal magnesia spinel growth apparatus comprising: a substrate supporting stand arranged therein; and (i) a CO_2 introduction tube opening into the reaction tube (a).