JPH01160900A - Method for liquid-phase epitaxial growth of semiconductor crystal and apparatus therefor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method and apparatus for liquid phase growth of semiconductor crystals, and particularly to a method and apparatus for growing crystals of ■-■ group compound semiconductors by a temperature difference method. It is.

[Conventional technology and problems]

Conventionally, when growing a semiconductor crystal such as a II-Vl group compound semiconductor, for example, as shown in FIG. A heat sink 3 made of a material with high thermal conductivity is attached and fixed so as to be in contact with the heat sink 3, and a cavity is formed below the heat sink 3, so that even if the heat sink 3 expands in the high temperature furnace during crystal growth, the In addition to preventing distortion from occurring in the quartz tube 1, a layer of Zn5 is placed on the heat sink 3 so as to be in close contact with the heat sink 3.
e Substrate crystal 4 is placed, and the substrate crystal 4 is fixed with a cylindrical quartz substrate fixing member 5. After that, a solvent 6 of Se and Te mixed to a predetermined composition and Zn as a growth material are added.
Insert source crystal 7 of 5e polycrystalline particles, 2 x 10
A growth ampoule 8 is manufactured by sealing off the upper end of the quartz tube 1 under a high vacuum of about -' Torr.

The growth ampoule 8 manufactured in this way is set in a heating furnace (not shown) that is preset to a predetermined temperature, and the inside of this heating furnace is heated to a temperature T6. By heating the solvent 6 at WB to a temperature T2 (Tz >'r, ) (see Figure 6) with a temperature gradient of approximately 10°C/cm, the solvent is placed on the heat sink 3. A crystal 9 is grown on the grown substrate crystal 4 by a temperature difference method.

In this case, first invert the top end of the growth ampoule 8 so that it faces downward, and heat the top end to a temperature higher than the growth temperature TI to uniformly dissolve Zn5e in Se and Te for about 2 hours. After performing so-called melt alloying to obtain a melt 6', the upper end of the growth ampoule 8 is rotated in the normal direction so that the upper end of the growth ampoule 8 faces upward to bring the melt 6° into contact with the substrate crystal 4. 1
．． The Zn5e pitaxial growth layer 9 is obtained at a rate of 0 to 10.0 μm/hr.

However, when performing melt alloying by inverting the growth ampoule 8, the temperature of the melt alloy may change.

Depending on the time, the Zn5e polycrystalline particles 7 may not necessarily completely dissolve in the solvent 6 to form a uniform melt 6''. For example, if the melt alloy temperature is low or the time is short, the Zn5e polycrystalline particles 7 may Crystal particles 7 are Se of solvent 6
, will not be completely dissolved in Te and will remain. In this state, when the growth ampoule 8 is rotated in the normal direction to start crystal growth, the remaining Zn
The Zn5e polycrystalline particles 7 fall onto the substrate crystal 4, and the Zn5e polycrystalline particles 7 are mixed as they are into the epitaxial growth layer 9 grown on the substrate crystal 4, resulting in good quality epitaxial growth. Layer 9 cannot be obtained.

For this reason, a method has conventionally been adopted in which crystal growth is performed by increasing the ratio of Te in the solvent 6, for example, at a molar ratio of Se:Te of 45:55 or more. By mixing Te into the epitaxial growth layer 9 crystal-grown on top, the epitaxial growth layer 9 becomes not Zn5e (Zn5eTe), and due to the radius of Te ions, etc., the crystals constituting the epitaxial growth Jt!9 Strain will occur in the crystal, which will deteriorate the optical properties of the crystal, and
In photoluminescence at low temperatures, an energy level with a wide and deep half-value width is generated in the forbidden band width and becomes dominant due to the presence of Te.

[Purpose of the invention]

In view of the above points, the present invention provides a liquid phase growth method that does not increase the ratio of Te in the solvent (and prevents residual Zn5e crystal particles from falling into an epitaxial growth layer grown on a substrate crystal). The purpose is to provide growth equipment.

[Means and actions for solving problems] The above purpose is to
According to the present invention, the present invention includes two quartz tubes of different diameters connected to each other, the lower end of the lower first quartz tube of small diameter is sealed flat, and the inner wall of the first quartz tube is sealed so as to be flat. A growth ampoule is used in which the solvent and source crystal are placed in a large-diameter second quartz tube on top of the heat sink, and the upper end of the second quartz tube is sealed in a high vacuum. II-
This is achieved by using an ingot having a size larger than the inner diameter of the first quartz tube as a source crystal in a temperature difference liquid phase epitaxial growth method or growth apparatus for Vl group compound semiconductors.

According to this invention, since an ingot is used as a source crystal, even if the source crystal does not completely dissolve in the solvent and remains after melt alloying is performed by inverting the growth ampoule, the remaining The size of the source crystal is selected to be larger than the inner diameter of the small-diameter first quartz tube that forms the growth ampoule, so that the source crystal can be placed between the first quartz tube and the second quartz tube in the form of an ingot. Since it is supported by the step formed in the connection area with the quartz tube, particles of the source crystal will not be mixed into the epitaxial growth layer during crystal growth, and the melt can be maintained uniformly. becomes.

Furthermore, since it is possible to set the mixing molar ratio of Ss and Te in the solvent to an arbitrary value, the crystals constituting the epitaxial growth layer grown on the substrate crystal will optically emit very little light due to Te. It will be of good quality with little or no production.

Furthermore, if the step part is located in the melt, the source crystal will be in contact with the melt during crystal growth, so by appropriately selecting the amount of the source crystal ingot, it will be possible to Spanning crystal growth is easily achieved, resulting in relatively thick epitaxially grown layers. Also,
If the step is located above the melt surface, the source crystal will not be in contact with the melt during crystal growth, so crystal growth will be limited by the amount of melt, and the time and temperature of melt alloying will be limited by the amount of melt. The thickness of the epitaxially grown layer depends on the time and temperature of the melt alloy, since the amount of dissolved source crystal is determined based on By controlling this, an epitaxially grown layer with a desired thickness can be obtained.

〔Example〕

The present invention will be described in detail below based on an embodiment shown in the drawings.

FIG. 1 shows a growth ampoule 10 used in an embodiment of a liquid phase growth apparatus for carrying out the present invention. A quartz tube 11 with an inner diameter of 15 to 20 mm, for example.
The first quartz tube 11 is connected to a large-diameter second quartz tube 12 in an upright manner so that the first quartz tube 11 is positioned downward, and the lower end of the first quartz tube 11 is made flat. For example, a heat sink 13 with a height of 80 to 200 mm is sealed so as to be in contact with the inner wall of the first quartz tube 11.
is attached and fixed with a slight cavity left at the lower end of the first quartz tube 11 so as to absorb the expansion of the heat sink 13 in the high-temperature furnace, and furthermore, it is placed on the heat sink 13 so as to be in close contact with the heat sink 13. A Zn5e substrate crystal 14 is placed in the substrate, and the substrate crystal 14 is fixed with a cylindrical quartz substrate stopper 15.
and then the second quartz tube 1 of the growth ampoule 10
Add a solvent 16 of Se and Te at an arbitrary predetermined mixing ratio up to 2, and add a source crystal 1 of Zn5e, which is a growth material, on top of it.
7, the upper end of the second quartz tube 12 is sealed off with a high vacuum of, for example, about 2 x 104 Torr, and its total height is, for example, 180 to 30,011 ff.
It has become l.

In this case, the source crystal 17 is an ingot such as a sintered body, and its size is selected to be larger than the inner diameter of the first quartz tube 11 and smaller than the second quartz tube 12. When housed in the quartz tube 12, it is supported by gravity on a step 11a formed in the connection area between the first quartz tube 11 and the second quartz tube 12.

This apparatus is constructed as described above, and when performing crystal growth, the growth ampoule 10 is first inverted into a heating furnace, as in the case of the conventional growth ampoule 8 shown in FIG. After setting and performing melt alloying, the growth ampoule 10 is rotated in the normal direction to start crystal growth. Even if the source crystal 17 remains during melt alloying, the source crystal 17 is not a polycrystalline particle. Since it is an ingot, the source crystal 17 does not fall onto the substrate crystal 14 during crystal growth, and a uniform, high-quality epitaxial growth layer 18 can be grown.

At this time, the second quartz tube 12 is filled with the melt 16° above the step portion 11a, so the source crystal 17 is in contact with the melt 16° as shown in the figure. By appropriately selecting the amount of 17,
A relatively thick epitaxial growth layer 18 can be easily obtained over a long period of time.

Next, an experimental example is shown in Fig. 2. In the liquid phase growth of Zn5e, the mixing ratio of Se and Te as a solvent was 50:50.
Using a substrate crystal with the same plane orientation and the same growth conditions, crystal growth was performed for 3 hours after melt alloying for 30 to 60 minutes.

As a result, with conventional equipment, the height of the center of the crystal! e is 2
0 to 25 μm, peripheral height I! , c is 9 to 12μ
In contrast, in the case of Zn5e polycrystalline particles falling onto the substrate crystal in the early stage of growth, the surface of the epitaxially grown layer 9 has many irregularities, and holes may also be formed (see Fig. 2 (A)). , in the device of the present invention, the height Ile of the center of the crystal
is 9 to 11 μm.

The height ff1c of the peripheral portion is 5 to 7 μm, and the surface is clean and almost mirror-like (see FIG. 2 (, B)).

Furthermore, when measuring the photoluminescence of the epitaxially grown layer, the mixing ratio of Se and Te in the solvent was 45:5.
In the conventional example where the mixing ratio is 85:15, as shown in FIG. In the case of using the apparatus of the present invention, as shown in FIG. 3(B), the above-mentioned peak does not occur, and DA pair light emission can be confirmed.

FIG. 4 shows a modification of the apparatus shown in FIG. 1, in which the growth ampoule 10° is not filled with melt 16° below the step 11a, that is, into the first quartz tube 11. Except for this, the structure is similar to that of the growth ampoule 10 shown in FIG.

In this case, the effect is almost the same as that of the growth ampoule 10 shown in FIG. 1, and since the source crystal 17 is not in contact with the melt during crystal growth, the crystal growth is limited by the amount of melt, and therefore Epitaxial growth layer 1
The thickness of No. 8 can be arbitrarily adjusted by appropriately controlling the melt alloying time and temperature.

〔Effect of the invention〕

As described above, the present invention includes two quartz tubes of different diameters connected to each other, the lower end of the lower first quartz tube of small diameter is sealed flat, and the lower end of the first quartz tube of small diameter is sealed flat. A heat sink is attached so as to be in contact with the inner wall of the quartz tube, and the solvent and source crystal are placed in a large-diameter second quartz tube above the heat sink, and the upper end of the second quartz tube is sealed under high vacuum. In a temperature difference liquid phase epitaxial growth method or growth apparatus for a II-Vl group compound semiconductor in which a semiconductor crystal is grown using a quartz ampoule, a cast quartz tube with dimensions larger than the inner diameter of the first quartz tube is used as a source crystal. Since this liquid phase epitaxial growth method or the growth apparatus is configured to use an ingot, the ingot is used as the source crystal, so after inverting the growth ampoule and performing melt alloying, the source crystal is placed in the solvent. Even if the remaining source crystals remain without being completely dissolved in the ingot, the size of the remaining source crystals is selected to be larger than the inner diameter of the small-diameter first quartz tube that forms the growth ampoule. In its original form, it is supported by a step formed in the connection region between the first quartz tube and the second quartz tube, so that particles of the source crystal are not mixed into the epitaxial growth layer during crystal growth. This will not occur and the melt will be maintained uniformly.

Furthermore, since it is possible to set the mixing molar ratio of Se and Te in the solvent to an arbitrary value, the crystals forming the epitaxial growth layer grown on the substrate crystals optically emit very little light due to Te. It will be of good quality with little or no production.

Furthermore, if the step part is located in the melt, the source crystal will be in contact with the melt during crystal growth, so by appropriately selecting the amount of the source crystal ingot, it will be possible to Spanning crystal growth is easily achieved, resulting in relatively thick epitaxially grown layers. Also,
If the step is located above the surface of the metal, the source crystal will not be in contact with the melt during crystal growth, so the crystal growth will be limited by the amount of melt, and the melt alloy will Since the amount of melted source crystal is determined based on the time and temperature of the melt alloy, the thickness of the epitaxially grown layer depends on the time and temperature of the melt alloy. By controlling the time and temperature, an epitaxially grown layer with a desired thickness can be obtained.

Thus, according to the present invention, the temperature difference liquid phase epitaxial growth method and growth method can be used to obtain a high-quality epitaxial growth layer without increasing the proportion of Te in the solvent and without the residual crystal grains of Zn5e falling onto the substrate crystal. Equipment will be provided.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of an embodiment of a liquid phase growth apparatus for carrying out the present invention, FIG. 2(A) is an enlarged sectional view of an epitaxially grown layer by a conventional apparatus, and FIG. FIG. 3 is an enlarged cross-sectional view of an epitaxially grown layer by the apparatus shown in the figure. Figure 3 (A) is a graph showing the photoluminescence characteristics of an epitaxially grown layer using a conventional device, Figure 3 (B)
2 is a graph showing the photoluminescence characteristics of an epitaxially grown layer by the apparatus of FIG. 1. FIG. FIG. 4 is a schematic sectional view similar to the first one showing another embodiment of the present invention. FIG. 5 is a schematic cross-sectional view showing an example of a conventional liquid phase growth apparatus;
FIG. 6 is a graph showing the temperature gradient in the apparatus of FIG. 10--Growth ampule; 11-First quartz tube; 12--M-Second quartz tube; 13--Heat sink; 14-Substrate crystal; 15--Substrate stop; 1
6-Solvent: 17-...Source crystal; ls'--Crystal grown epitaxial growth layer. Patent applicant: Stanley Electric Co., Ltd. Representative: Patent attorney Hirayama - Device: Patent attorney Kaizu Tamotsu SanT+
72:, +t Figure 3 (A) Se/Te-45155 Energy (eV) Figure 3 (B) Se/Te=85/15 Energy'- (eV) Procedural amendment (voluntary) February 24, 1988 Japan Patent Application No. 319792, filed in 1988 2, Name of the invention: Liquid phase epitaxial growth method and growth apparatus for semiconductor crystals 3, Relationship with the case of the person making the amendment Patent applicant address: 2-9-13 Nakameguro, Meguro-ku, Tokyo Name (2
30) Stanley Electric Co., Ltd. 4, Agent address: 9th floor, Build Kitsunichi, 4-30-23 Yotsuya, Shinjuku-ku, Tokyo 160 Tel: 03 (352) 1808] 6. Subject of amendment (1) Corrected drawings (first) 1 7th
, Contents of amendment (1) rle on page 11, line 14 of the specification is 20 to 25
μm, peripheral height I! , c is corrected to ``jec is 20 to 25 μm9 and the height Re of the peripheral portion is''. (2) "I!, ega" on page 11, line 19 of the same page is replaced with "i!,
Correct it to "c". (3) “I/2e” for “I!, cga” on page 11 of the same page”
Correct to. (4) Figure 1 in the drawings will be corrected as shown in the attached sheet. Procedural amendment cap button March 22, 1988 Kunio Ogawa, Commissioner of the Patent Office1, Indication of the case Patent Application No. 319792 of 19882, Name of the invention Liquid phase epitaxial growth method and growth apparatus for semiconductor crystals3, Relationship with the person making the amendment Patent applicant address 2-9-13 Nakameguro, Meguro-ku, Tokyo Name (2
30) Stanley Electric Co., Ltd. 4, Agent address: 9th floor, Build Yoshida, 4-30-23 Yotsuya, Shinjuku-ku, Tokyo 160 Phone number: 03 (352) 18086, Drawing 7 subject to amendment, Drawing 4 showing content of amendment as attached. correct.

Claims (2)

[Claims] (1) Includes two interconnected quartz tubes with different diameters, the lower end of the lower small-diameter first quartz tube is sealed flat, and the lower end is in contact with the inner wall of the first quartz tube. Attach a heat sink, place the solvent and source crystal in a large-diameter second quartz tube above the heat sink, and grow the semiconductor crystal using a growth ampoule with the upper end of the second quartz tube sealed in high vacuum. In the temperature difference liquid phase epitaxial growth method for II-VI group compound semiconductors, which grows crystals, an ingot with a size larger than the inner diameter of the first quartz tube is used as the source crystal. liquid phase epitaxial growth method. (2) It includes two interconnected quartz tubes with different diameters, the lower end of the lower first quartz tube of small diameter is sealed so as to be flat, and the lower end is sealed so as to be in contact with the inner wall of the first quartz tube. Attach a heat sink, place the solvent and source crystal in a large-diameter second quartz tube above the heat sink, and grow the semiconductor crystal using a growth ampoule with the upper end of the second quartz tube sealed in high vacuum. A temperature difference liquid phase epitaxial growth apparatus for II-VI group compound semiconductors, characterized in that an ingot with a size larger than the inner diameter of the first quartz tube is used as a source crystal. Phase epitaxial growth equipment.