JPH09320965A - Method for manufacturing compound semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance selectivity by forming a protective film on a portion of surface (100) having an off angle in a specific range of a III-V compound semiconductor single crystal, and growing a thin film of a III-V compound semiconductor single crystal selectively after that. SOLUTION: To enhance selectivity, selective growth is performed on surface (100) having an off-angle of 0.5-30 deg., through 1-4 deg. is more preferable, of a III-V compound semiconductor single crystal. As to the direction of the off-angle, fundamentally any direction will do, but direction <011>A' <011>B or <010> is favorable. Most of all, direction <010> is the most favorable. Besides, the direction of the off-angle is not always necessary to be exactly one of these, but is does not matter if it is within 30 degrees, through within 20 degrees is more favorable. Consequently, it becomes possible to enhance selectivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a compound semiconductor layer in vapor phase growth of a compound semiconductor thin film made of a hydride and an organic metal as a raw material, and particularly to suppressing deposition on a protective film for selective growth. The present invention relates to a method for producing a compound semiconductor suitable for

[0002]

2. Description of the Related Art Recently, selective growth has been used as one of the techniques for optimizing the device structure of compound semiconductors. However, since selective growth is difficult with the MBE method, it is usually MO.
The CVD method is used. The advantages of the MOCVD method in selective growth are that there is almost no damage to the substrate or the epitaxial growth layer and that the process can be performed at a relatively low temperature, so that a high-quality selective growth region can be obtained.

However, when selective growth is performed, growth conditions, mixed crystal ratios, mask widths, etc. are greatly restricted in order to prevent polycrystal deposition on the protective film. In particular, in the case of a compound containing Al, there is a problem that the higher the mixed crystal ratio of Al and the larger the mask width, the easier the polycrystal is deposited on the protective film. As a solution to this problem, it has been reported that the deposition of polycrystals on the protective film can be avoided over a wide range by adding a halide method and / or a halogen gas which does not include the host element of the compound to be grown during the selective growth. ing. (WO93 / 01614)

[0004]

However, there are cases where the selectivity is not sufficient even when the above method is used. In particular, the selectivity may not be sufficient when the area protected by the protective film is large or when the area where selective growth is desired to be performed on the protective film is extremely narrow.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that when a selective growth is performed by adding a halide gas and / or a halogen gas, a specific crystal growth surface is They have found that the selection can improve the selectivity, and have reached the present invention. That is, the gist of the present invention is to form a protective film on a part of the {100} plane of a III-V compound semiconductor single crystal having an off-angle of 0.5 to 30 °, and then form a III-V compound semiconductor raw material A method for producing a compound semiconductor, comprising a step of adding a halide gas and / or a halogen gas together with a gas to selectively grow a III-V group compound semiconductor single crystal thin film in a portion where the protective film is not formed. Exist in.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
In the present invention, in order to improve the selectivity, the selective growth is performed on the {100} plane where the off-angle of the III-V compound semiconductor single crystal is 0.5 to 30 °, preferably 1 to 4 °. I am trying. The off-angle direction may be basically any direction, but the <011> A direction, the <011> B direction or the <010> direction is preferable, and the <010> direction is most preferable. Also, the off-angle direction does not necessarily have to be the direction of these directions, and is ± 3
The direction may be within 0 °, more preferably within ± 20 °. In this specification, the <011> B direction is the direction of the orthogonal projection of the normal line of the {111} B plane from which the group V element appears on the {100} plane. That is,
For the (100) plane shown in FIG. 1a, [0-11] and
The stripe-shaped protective film formed in this direction, which is the direction represented by [01-1], is shown in FIG. 1b. Other {10
With respect to the 0} plane as well, a direction crystallographically equivalent to this may be selected. The <011> A direction is the direction of orthogonal projection onto the {100} plane of the normal line of the {111} A plane where the group III element appears on the surface.

In order to carry out selective growth on this {100} surface, a known protective film such as silicon nitride or silicon oxide is provided on a part of that surface, that is, a portion where growth is unnecessary. In many cases, the protective film has a stripe shape. In that case, if the direction of the stripe is within ± 45 °, more preferably within ± 30 ° from the direction perpendicular to the off-angle direction, the selectivity is further improved, which is preferable. . Further, in such a stripe-shaped protective film, the width of the short side is 50 μm or more, and the ratio of the protective film forming region to the thin film forming region on the {100} plane is 1 or more, preferably 2 or more, and most preferably 2. In some cases, it may be preferable to form it so as to be 5 or more. When manufacturing a broad area laser, etc., or when it is necessary to locally increase the growth rate, such a protective film formation area is large, and it is required to narrow the growth area. However, according to the present invention, growth can be performed with high selectivity by selecting the orientation of the protective film.

As the raw material gas of the compound semiconductor used in the present invention, any of known materials such as organic metals, hydrides and chlorides can be used, and as the organic metals, trimethyl galium (TMG) and triethyl gallium (TEG) are used. ), Trimethylaluminum (TMA), triethylindium (TMI) and the like are arsine (A
sH ₃ ), phosphine (PH ₃ ), and the like, and chlorides such as gallium chloride (GaCl), diethylgallium chloride (DEGaCl), and arsenic trichloride (AsCl ₃ ).
Among these, chlorine-free organometals and chlorine-free hydrides are preferable from the viewpoints that the growth mechanism is relatively simple, and precise growth rate control is relatively easy. Further, the effect of improving the selectivity of the present invention is great especially when an organic metal is used.

As the halide gas, HBr, HI, H
Hydrogen halides such as F and HCl, and carbon halides such as CCl ₂ F ₂ can be used as halogen gas such as Cl ₂ , I ₂ , F ₂ ,
Br _{2 and the} like, and mixtures thereof, and preferably HCl. In addition, when the above-mentioned chloride is used as the source gas and a compound semiconductor single crystal thin film having an Al mixed crystal ratio of 0.3 to 0.4 is grown, a halide gas or a halogen gas is separately added. Without introducing
Growth can be performed with some selectivity.

The amount of the halide gas and / or halogen gas used depends on the size of the growth chamber, the growth temperature, the growth pressure, the type of raw material used, etc., but if the amount is too large, the thin film growth stops and etching occurs. It becomes the etching mode area which becomes, and when it is too small, it becomes the deposition mode area where the polycrystal grows on the protective film. Therefore, adjust the flow rate of halide gas and / or halogen gas appropriately to avoid these areas. The selective mode is performed in a selective mode in which a crystal grows in a desired region but a polycrystal does not grow on the protective film.

The total pressure of the gas during the growth is preferably atmospheric pressure or lower, and the growth temperature may be the conditions generally used in the vapor phase growth, generally about 500 to 900 ° C.
On the low temperature side, the selectivity tends to decrease, and on the other hand, if it is too high, re-evaporation of III-V group elements and incorporation of impurities may become a problem, so 600 to 850 ° C., more preferably 650 to 800 ° C. The degree is good. However, the effect of the present invention, that is, the effect of improving the selectivity depending on the plane orientation and the direction of forming the protective film is remarkable on the lower temperature side, that is, about 500 to 700 ° C., and the present invention is effective under relatively mild conditions. It is also useful in that selective growth can be performed.

The manufacturing method of the present invention is effective for the growth of ordinary III-V compound semiconductor thin films, but is particularly suitable for the growth of III-V compound semiconductors containing aluminum. Specifically, AlInGaP, InAlAs, AlInP, A
lGaAs and the like, and particularly suitable for AlGaAs.

[0013]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the invention. (Example 1 and Comparative Example) Each surface is (100)
Plane, a plane inclined by 2 ° in the [0-11] direction from the (100) plane,
A width of 300 μm made of silicon nitride on a GaAs substrate, which is a plane inclined by 2 ° from the (100) plane in the [0-1-1] direction or a plane inclined by 2 ° from the (100) plane in the [0-10] direction. The stripe-shaped protective film of [0-
11] direction (FIG. 1b: B direction) or [011] direction (FIG. 1c: A direction) at 100 μm intervals, and then an Al _0.3 G film with a thickness of about 0.5 μm is formed by MOVPE.
A compound semiconductor was manufactured by selectively growing an a _0.7 As layer. Trimethylgallium (TMG) is used as the source gas
2.7 × 10 ⁻⁴ mol / min, trimethylaluminum (T
MA) 1.0 × 10 ^-4 mol / min and arsine (As
H ₃ ) 250 sccm (standard cubic cm per minute), with hydrogen as a carrier gas, the total flow rate of gas is 22 sl
It was supplied so as to have m (standard cubic liter per minute), the growth temperature was 660 ° C., the growth pressure was 133 hPa, and 4 cc of hydrogen chloride was added during the growth. The results of observation with a differential interference optical microscope are shown in Table 1. The results were evaluated according to the following criteria. ○-○ Polycrystalline deposition is not observed at all on the protective film ○-△ Slight polycrystalline deposition is observed on the protective film ○-× Polycrystalline deposition is sparsely observed on the protective film △- ○ A part where polycrystal deposition continues to be seen in the central part of the protective film △-△ A part where polycrystal deposition continues in the central part of the protective film (with a gap) △-× Center of the protective film There is a continuous polycrystal deposit in the area (no gap) × − ○ About half of the protective film is covered by the polycrystalline deposit × − △ Most of the protective film except the edges is polycrystalline The entire protective film is covered with polycrystal.

[0014]

[Table 1]

(Embodiment 2) From the (100) surface to [0
-1-1] direction, except that only a GaAs substrate having a surface inclined by 2 ° in the direction of −1) was used and an Al _0.3 Ga _0.7 As layer was selectively grown at a growth temperature of 580 ° C., 660 ° C. or 780 ° C. A compound semiconductor was manufactured in the same manner. The results are shown in Table 2.

[0016]

[Table 2]

[0017]

According to the present invention, it is possible to grow a group III-V compound semiconductor thin film only in the growth region with good selectivity without depositing a polycrystal on the protective film.

[Brief description of drawings]

FIG. 1A is a top view of a model showing the plane orientation of a III-V compound semiconductor single crystal as seen from the (100) plane side. 3B is an explanatory view of the direction of the stripe-shaped protective film formed in the <011> B direction in each of the examples and comparative examples. c is an explanatory diagram of the direction of the stripe-shaped protective film formed in the <011> A direction in each example and comparative example.

[Explanation of symbols]

 A. Surface where Group III element is the surface B. A surface on which the group V element is the surface 1. Striped protective film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideki Goto 1000, Higashihuinana-cho, Ushiku-shi, Ibaraki Mitsubishi Chemical Corporation Tsukuba Plant

Claims (7)

[Claims] 1. A halide is formed with a source gas of a III-V compound semiconductor after forming a protective film on a part of a {100} plane having an off-angle of 0.5 to 30 ° of a III-V compound semiconductor single crystal. Gas and / or halogen gas,
A method for producing a compound semiconductor, comprising a step of selectively growing a III-V compound semiconductor single crystal thin film on a portion where the protective film is not formed. 2. The method according to claim 1, wherein the protective film has a stripe shape. 3. The off-angle direction is <010.
Within ± 30 ° from the> direction, within ± 30 ° from the <011> A direction or ± 30 from the <011> B direction
3. The method according to claim 1, wherein the direction is within °. 4. The direction of the stripe-shaped protective film is
4. The method according to claim 2, wherein the direction is within ± 45 ° from the direction perpendicular to the off-angle direction. 5. The method according to claim 1, wherein the halide gas is hydrogen halide or carbon halide. 6. The temperature of the selective growth is 500 to 900.
The method according to any one of claims 1 to 5, wherein the temperature is ° C. 7. The striped protective film has a short side width of 50 μm or more and a ratio of the protective film forming region to the thin film forming region on the surface is 1 or more.
the method of.