JPS60124817A - Vapor-phase epitaxial growth method - Google Patents

Abstract

PURPOSE:To improve the crystallizability of a silicon grown layer as well as to accomplish the uniform flatness and increase in mobility of electron on the surface thereof in an excellent reproducibility by a method wherein molybdenum is adhered to the surface of a single crystal substrate of magnesia spinnel or sapphire. CONSTITUTION:The magnesia spinnel single crystal substrate 23 whereon a cleaning process has been performed, is arranged on a carbon pedestal 22. The molybdenum located in a source boat 26 is heated up by a resistor 27, a molybdenum oxide is formed by introducing the mixed gas of O2 and N2 from a gas introducing hole 29a, and it is sent to the substrate 23 by gas and adhered there. The H2 gas to be introduced from gas introducing holes 29b and 29c is sent to the substrate 23 as a carrier, and a silicon epitaxial growing method is performed. Molybdenum is used by dissolving the molybdenum compound such as an oxide, a chloride or a nitrate, or a molybdenum alloy using the suitable inorganic or organic medium such as water, an acid, alcohol and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a silicon vapor phase epitaxial growth method, in which the epitaxial growth of silicon on a magnesia-subine J or sapphire single crystal surface is carried out by uniform debossing. The present invention relates to surface treatment of a growth surface for improving electrical characteristics.

(b) Background of the Technology If semiconductor elements such as transistors are directly formed on an insulating substrate, the following effects can be obtained.

(a) Electrical isolation between each element is easily and reliably achieved, improving reliability of operation.

Middle) There is less interference between the element phases 1, and the element spacing can be shortened to achieve high performance.

(c) Since there is no capacitance with the substrate and the wiring parasitic capacitance is negligible, transient power is significantly reduced and the operating speed per frequency % is improved.

In order to realize this structure, epitaxial growth of a silicon single crystal layer on an insulating substrate was achieved using sapphire (
5(JS (Sili
conon8apphiri structure (known), and along with sapphire, Magui, shea spinel (M
g1J-Aj, Os) crystal is used as a substrate.

A so-called three-dimensional structure has been attempted with the aim of improving the reliability of semiconductor circuit devices. In order to realize a three-dimensional structure, it is necessary to alternately laminate insulating layers and silicon single crystal layers on a silicon single crystal substrate, for example. Epitaxially grown insulation (EGI), which enables growth in a lattice-matched manner to the substrate.
Attempts have previously been made to provide wn inlurators with magnesia spinel. In this case, a single silicon crystal layer is epitaxially grown on a magnesia spinel crystal.

(C1 Prior art and problems) Silicon fast crystals and magnesia spinel single MA both have cubic crystal threads, but for example, the lattice constant of the bulk single crystal is 0.5431 nm for silicon and 0.8083 nm for magnesia spinel. There is a large difference between the two, such as the fact that silicon single crystal layers grown on magnesia spinel crystals conventionally contain many defects such as single dislocations, the growth plane is not smooth, and Its electrical properties are inferior, such as carrier mobility being lower than that of a bulk crystal.These defects become more severe as the silicon single crystal layer becomes thinner, and as the thickness increases, carrier mobility and other problems improve.

Many efforts have been made to elucidate the mechanism of crystal growth under such conditions, and it has been discovered that in the early stages of growth, three-dimensional microscopic crystals are formed in the form of islands, and crystals grow using these as nuclei. The density of the formed nuclei is dominated by the reaction on the surface of the crystal such as magnesia and spinel, and strongly depends on the growth temperature. The crystallinity and electrical properties of the crystal in the crystal layer are greatly influenced by the initial growth state, and furthermore, the closer the layer is to the interface with the magnetic material, the greater the influence of the unstable interface, and the greater the defect density. It is known that.

In order to reduce the defects and improve the properties of the silicon single crystal layer grown on magnesia spinel or sapphire single crystal by the vapor phase epitaxial growth method, for example, the growth temperature, growth rate, etc. In addition to optimizing the growth conditions that are normally considered, it was judged necessary to pay attention to the surface condition of magnesia spinel or sapphire, which serves as the growth plate, in order to improve the initial growth condition. Ru.

fd+ Object of the Invention The present invention provides a substrate that improves the crystallinity, electrical properties, etc. of the grown silicon single crystal layer when a silicon fraction crystal is grown in a vapor phase on a magnesia spinel or sapphire single crystal. The purpose of the present invention is to provide a method for surface treatment of crystals.

te+ Structure of the Invention The object of the present invention is to contact the surface of a magnesia spinel or zaphire single crystal substrate with a substance containing molybdenum to deposit the molybdenum, and then deposit silicon on the surface of the single crystal substrate. This is achieved by growing a single crystal in a vapor phase.

The adhesion of molybdenum to the crystal surface of the substrate on which silicon single crystal growth is performed, which is a characteristic of this method, is carried out after the cleaning treatment such as etching, degreasing, and cleaning of the surface that is conventionally performed on the substrate crystal. .

A molybdenum compound as the molybdenum-containing substance,
Capacity can be used. The solution includes molybdenum, a molybdenum compound such as an oxide, chloride or nitrate, or a molybdenum alloy, for example, water,
It can be used after being dissolved in a compatible inorganic or organic solvent such as alcohol.

A solution suitable for the present invention is a solution of molybdic acid in hydrogen peroxide. The concentration is 1 x t of molybdic acid for 1 [t] of 31 [thi] hydrogen peroxide aqueous solution.
It is valid in the range from o-'[:g) to txto''l:g), but it is valid in the range from lX1o'(g/l) to l[g/l
The following concentration ranges are particularly preferred.

Further, as the molybdenum-containing FTPIJ, a gas containing molybdenum and/or a molybdenum compound, hydrogen, and nitrogen or an inert gas can be used.

Furthermore, according to the present invention, molybdenum is attached to the surface of magnesia spinel or sapphire single crystal.
It becomes possible to use silicon tetrachloride (SIct) 11 instead of the conventional butene (Sict) 11 as a raw material gas for vapor phase epitaxial layer growth of silicon single crystal.

(f) Embodiments of the Invention As described above, by depositing molybdenum on the surface of a magnear spinel or sapphire single crystal substrate, the epitaxial growth of silicon on the substrate surface is greatly improved. Atoms do not impair the crystallinity of magnesia spinel and sapphire,
It acts with the acid 'JA atoms existing near the surface to inhibit the separation of these gap atoms from the substrate crystal, and the molybdenum atoms diffused near the surface of the substrate crystal cause disorder in the crystal lattice and the substrate crystal. The effect of mitigating the mismatch between the silicon crystal and the silicon crystal is that many crystal nuclei are effectively formed in the initial stage of silicon crystal growth, improving the uniformity and stability of silicon epitaxial growth. It is judged that.

Hereinafter, the present invention will be specifically explained using examples and with reference to the drawings.

(1) First Example Molybdenum is dissolved in aqua regia to prepare a saturated solution at a temperature of 5 degrees Celsius, which is diluted with distilled water. The dilution ratio is 103 to 108 times, but usually 10' to 106 times is preferred.

A magnesia spinel single crystal substrate that has been cleaned according to the conventional technique E is immersed in this diluted fIg, and dried using a spin dryer or the like.

A substrate subjected to molybdenum adhesion treatment according to the present invention,
As a comparative sample, a high-frequency heating type vapor phase growth apparatus was used according to the conventional technology on a substrate that did not undergo round burying according to the present invention.
91H, vapor phase growth of a silicon single crystal is carried out.

FIG. 1 is a schematic cross-sectional view showing an example of a high-frequency heating type vapor phase growth apparatus. Magnetic screw 'γ・Subine J is placed on the carbon pedestal 2 provided in the quartz reaction '11, and the single crystal substrate 3 is attached.
is placed, and the temperature of the substrate 3 is heated to about 1.100 ('IC) through high frequency power through the coil 4I. Container 5
When SiH is introduced into the reaction tube 1 using water (1f-CHZ) as a carrier, 8iH is decomposed and silicon penucrystals grow on the substrate 3.

In this example ζ, the silicon growth temperature i, i o
.

[°C], a growth rate of 1.5 [μm/min], and a growth layer thickness of about 7 [μm], the unevenness on the surface of the growth layer of the comparative sample is about ±250 [μm], and the arsenic (AsJ doped) Concentration approximately 2×1015 [electron mobility in cIL-9 μm 9
00 [-/V@S), the surface of the grown layer subjected to the saturation of molybdenum deposition is glossier than that of the comparative sample, and its unevenness is about ±50 [nm], which is less likely to cause electron transfer. degree μm 1. 1 OO (aJ/V・S), which is clearly improved.

(II) Second Example Molybdenum is dissolved in aqua regia, dehydrated and dried to obtain a true color powder called molybdenum blue. 31 (%)
The molybdenum compound oxide was dissolved in a solution prepared by diluting an aqueous hydrogen peroxide solution twice with distilled water.

The concentration of this molybdenum compound is lx 1o-' Cg/
z) to I x 10' (g/l), a magnesia spinel single crystal substrate that has been subjected to a cleaning treatment using a conventional technique is immersed in these liquids for about 1 minute, and then dried using a spin dryer or the like. .

In this example, silicon tetrachloride (8iC) was deposited on this substrate.
1,) is used as a raw material gas to grow a silicon single crystal. As the growth apparatus, the same apparatus as in the case of using 8iH as the raw material gas in the above embodiment can be used. However, while 51H4 is a gas at room temperature, 8iC7 is a liquid, so a carrier gas such as H gas is bubbled within the 5IC 44 to mix both gases.

In this example, for example, when a substrate i is immersed in a solution with the above concentration, the substrate temperature is 980 ('C), and 5iC4
temperature 30 [℃], carrier H, gas flow rate 20
[t/min: l, flow rate of 81CA4 10 (cc
/min) and t, the growth rate of silicon single crystal is approximately 55 [Tsukuda Vmin), and the thickness of the growth layer l[
μm] to obtain a single crystal with an electron transfer summer μΩ of 400 [cd/V-8] 0 Conventionally, when silicon is epitaxially grown on magnesia spinel and sapphire single crystals, S I ct is used as the raw material gas. The commonly used growth temperature is 900 to 1,100.
c'C), which is impossible under the growth conditions of a growth rate of 0.05 to 2 [μm/m1n], and even if a film is formed, it is usually in a multi-crystalline Jk& state.

For this purpose, silane (8'H4J), which is a hydride, has traditionally been used as a raw material gas.
In, requires special care in handling as it spontaneously combusts in the air, and also has problems such as impurity Ct during growth and higher price.

By attaching molybdenum to the growth surface according to the present invention, it becomes possible to grow silicon single crystals on magnesia spinel or sapphire crystals using S]Ct4 as a raw material, as in the above embodiments. , 5t) 14 as described above was solved. Third Example Metallic molybdenum [purity 99.99 (chi) or higher] was converted into 31 [
[H] Hydrogen peroxide (Hz Oy) dissolved in a saturated solution of water,
This bath solution is heated and dehydrated to form a gel, which is further dehydrated and dried to produce yellow molybdic acid powder.

This molybdic acid powder 431 is dissolved in an aqueous solution of [thi]HtOt. The concentration of this solution is 31C]Hz O
10 molybdic acid powder to x water s liquid i (t)
Nine levels are prepared from -' (g) to 10'' [g:].

Above is a Magnena spinel single crystal substrate that has been cleaned using conventional technology! Immerse it in the liquid for about 1 minute and dry it with a spin dryer.

] by the same method as in the first embodiment, 81)
1. Epitaxial growth of silicon is carried out using as a raw material gas. However, in this example, the following growth conditions are applied. That is, the preheating temperature is 1,100
C℃), growth temperature 950('C), H寞'R*2
0 (17m1n), 81H, flow it 4 5 (c
c/min), As doping concentration 2×1O15 [cII
L-3], the growth rate is approximately 0, s (μm/m1n) tel.

As a comparative sample, silicon was epitaxially grown under the same conditions on a substrate which was not subjected to the molybdenum adhesion treatment according to the present invention.

Figure 2 shows an example of measuring the unevenness of the surface of the silicon growth layer of the comparative example and non-example using a tarry step.
1 and (b). However, the case where the concentration of the above-mentioned solution is I x 10" Cg/l is shown as an example, and in both cases, the thickness of the silicon growth J- is about 0.9".
[μm]] shows a state in which the elapsed time after the start of growth is short.

FIG. 2(a) shows a comparative sample, and FIG. 2(b) shows the unevenness of the surface of the silicon growth layer obtained in Example 1, but the intermediate shape of the comparative sample with a large difference is not depicted. From this U, the difference between bacteriolysis and the lowest value is approximately 60 (nm, l) for the comparison sample.
On the other hand, in this example, it is about 24 (nm)
Figure 3 shows an example of the electron mobility μn when the thickness of one silicon growth layer is approximately 8 μm for this example and the comparative example 1a. FIG. In the figure, the horizontal axis indicates the concentration of the molybdic acid solution, and the broken line in the figure indicates an example of a comparative sample without molybdenum deposition according to the present invention.

From Figure 3, the concentration of the intoxicant at least 10-6 to xo
The effect of introducing molybdenum into the substrate surface according to the present invention is recognized in the range of 2 (g/l), and the electron mobility fin is 1,200% in the concentration range of 10-4 to 100 [g/l]. /V' 8) was obtained, which is significantly improved from the comparative example of approximately 880 (cIIl/V Even if repeated, the state of the silicon epitaxial growth layer remains.

No change observed in characteristics? 1! It was confirmed that silicon growth was performed well.

Furthermore, with regard to the molybdenum aqua regia solution used in the first example, changes over time are observed when the solution is stored, but even with this in mind, the solution of this example was excellent. -(1ψ Fourth Embodiment As shown in FIG. 4, metal molybdenum 12
A magnesia spinel single crystal substrate 13 is arranged, and molybdenum 12 is heated to a temperature of 800 [
The substrate is heated to about 400 to 500 degrees Celsius. A gas having an oxidizing effect such as fig (0*) or carbon dioxide (COi) is introduced into the reaction tube 11 from the gas inlet 15 using hydrogen (H!) gas as a carrier gas.This 0! or CO, etc. As a result, the metal molybdenum 12 is oxidized and molybdenum oxide is sublimated, transported by the carrier gas, and deposited on the 1-magnesia O spinel single crystal substrate 13.

As a result of vapor phase deposition of silicon single crystal to a thickness of approximately 8 to 1 μm under the same conditions as in the first example, the surface of the grown layer was It was shiny, the unevenness was about ±60 [nm], and the electron mobility was 1,100 [:i/V, 8), which was an improvement comparable to that of the first example.

(Vl Fifth Embodiment Using an apparatus as shown in FIG. 5, molybdenum deposition according to the present invention and silicon single crystal growth can be performed continuously in the same apparatus.

In the figure, 21 is a quartz reaction tube, 22 is a carbon pedestal, 23 is a magnesia spinel single crystal substrate, 24 is a high frequency coil, 25 is a source chamber, 26 is a source port, 27 is a heating resistor, 28 is a bubbling container, 29
a, 29b and g9c are gas inlets, 30 is a gas outlet, and a source port 26 houses a metal molybdenum bubbling container 28.

After the cleaning process has been completed, the substrate 23 is placed on the carbon vedestal 22, and first a molybdenum adhesion process is performed. That is, the source port 26 is connected by the resistor 27.
The molybdenum inside is heated to a temperature of about 800 to 900 ('C), and a mixed gas of, for example, O3 and N is introduced from the gas inlet 29a to generate molybdenum oxide. This generated molybdenum oxide is transferred to the gas and gas inlet 2.
The H2 gas introduced from 9b transports it to the substrate 23 and attaches thereto. This process is carried out for about 30 seconds, for example.

Next, the temperature of the substrate 23 is set to about 900 to 1150 ('C), and H8 gas is passed into the bubbling container 28 to inject 8 ICs.
Epitaxial growth of silicon is performed in the same manner as in the fourth embodiment by sending 24 gas to the substrate 23 using H gas introduced from both gas inlets 29b and 2900 as a carrier.

The method of carrying out the deposition of molybdenum according to the present invention and the subsequent epitaxial growth of silicon using the same equipment as in this embodiment not only improves workability but also prevents unintentional impurity mixing and other contamination. It has the effect of preventing

In the third embodiment described above, the metal molybdenum is H! Molybdic acid produced by dissolving OR water ff#g, 4 is used, but commercially available molybdenum oxide, molybdic acid and its salts, that is, M00□M0U,
・IH, U, M, 0.・2 Hz O, (NH4)2・
, QMoo, etc. can be dissolved and used as in the above method to obtain the same effect.

Further, using a solution in which other molybdenum compounds such as molybdenum chlorides and salts, or metal molybdenum or molybdenum alloys as in the first embodiment are dissolved in compatible solvents such as various acids, aqueous ammonia, alcohol, or water. However, the effects of the present invention can be obtained.

Similarly, in the fourth and fifth embodiments 1, a manufacturing method is used in which metal-limited molybdenum is oxidized in the apparatus, but
Similar effects can also be obtained by using various molybdenum compounds such as oxide chlorides as raw materials and vaporizing them. The oxidation of metal molybdenum can also be carried out at high temperatures using an oxidizing gas such as nitrogen oxide or water vapor, or as a carrier gas.
■In addition to gas, nitrous (N2) gas or helium (H),
An inert gas such as argon (kr) can be used.

Furthermore, in the above explanations, silicon single crystals are epitaxially grown on magnesia spinel single crystals, but even when the substrate is sapphire, good silicon single crystals can be grown with good reproducibility in the same manner as in the case of magnesia spinel single crystals. It becomes possible to grow.

(gl As described in detail of the invention, in addition to the epitaxial growth of a silicon single crystal on a magnesia spinel single crystal or a fire part crystal surface, the present invention I allows molybdenum to be deposited on the growth surface 4. The crystallinity of the silicon growth layer is significantly improved, and, for example, the surface leveling and electron mobility are increased with good reproducibility.

As a result, it becomes possible to form a semiconductor integrated circuit having excellent characteristics, which has a great effect on the promotion of semiconductor devices having an 80 square structure or a three-dimensional structure.

This invention makes it possible to use silica tetrachloride as a raw material gas for silicon vapor phase growth on magnesia spinel single crystals or zapphire viscous crystal surfaces, compared to conventional silane raw material gas. As a result, the same effects as mentioned above can be obtained in terms of workability and economy.

[Brief explanation of drawings]

Figure 1 is a schematic sectional view showing an example of a vapor phase growth apparatus, and Figure 2 (
a) and (bJ show examples of unevenness on the surface of the growth layer; (d)
(b) is a diagram showing a conventional example, (b) is a diagram showing an example of the present invention, FIG. 3 is a diagram showing an example of the correlation between molybdic acid @ liquid concentration and electron mobility, and FIG. FIG. 5 is a schematic cross-sectional view of an apparatus capable of successively performing molybdenum deposition using a gas and silicon vapor phase deposition. As shown in the figure, 1 is the anti-Yum tube, 3 is the board, 4 is the coil, and 5
11 is a reaction tube, 12 is molybdenum,
13 is a substrate, 14 is a resistor, 21 is a reaction tube, 23 is a substrate, 24 is a coil, 26 is a source port, 27 is a resistor,
28 indicates a bubbling container. 1st command 2nd g unconcealed 8m 粁h〃ρ ′$ 3g 9], E4/Bude 4; tl rl/z]

Claims (1)

[Claims] (11 5 iL of a substance containing molybdenum is brought into contact with the interface of a monocrystalline crystal substrate of magnesia spinel or sapphire to adhere the molybdenum, and then a silicon single crystal is deposited on the surface of the single crystal substrate. A vapor phase epitaxial growth method characterized by vapor phase growth. (2) Using a gas containing silicon tetrachloride as a raw material gas,
2. The vapor phase epitaxial growth method according to claim 1, wherein said silicon single crystal is grown in vapor phase. (3) The vapor phase epitaxial growth method according to claim 1 or 2, wherein the substance containing molybdenum is a solution of a molybdenum compound. (4) The vapor phase epitaxial growth method according to claim 3, wherein the solution of the molybdenum compound is an aqueous solution of hydrogen peroxide at the molybdenum position. (5) Claim 1, characterized in that the acoustic substance containing molybdenum is a gas containing molybdenum and/or a molybdenum compound, hydrogen, and an inert gas.
The vapor phase epitaxial growth method according to item 1 or 2.