JPH05178686A - Metallic block for liquid phase epitaxy and its production - Google Patents

Abstract

PURPOSE:To provide a metallic block for liquid phase epitaxy used as a solvent for making the distribution of dopant concentrations uniform. CONSTITUTION:A dopant housing part 2 where granulated dopants are housed and held is formed on the surface of a metallic block 1 which is almost semicircular as a whole. For the dopant housing part 2, recessed parts 3 formed on the surface of the metallic block 1 while dispersing them uniformly are suitable. The metallic block 1 is produced by casting a metal having high-purity and a low melting point.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low melting point and high purity metal block used as a solvent in liquid phase epitaxial growth and a method for producing the same.

[0002]

2. Description of the Related Art When a substrate for an optical semiconductor such as a laser diode is manufactured by a liquid phase epitaxial growth method (LPE method), a low melting point metal such as indium or gallium is used as a solution solvent. Since this solvent is required to have a high degree of purity, it is used by casting a highly purified metal in a mold.

FIG. 5 and FIG. 6 show a liquid phase epitaxial growth apparatus using a conventional metal block (13) as the solvent, and this apparatus will be described.

As shown in FIG. 5, a plurality of substrates (9) are fitted into a belt-shaped substrate holding and conveying body (8) at equal intervals. The substrate holding carrier (8) slides under the frame-shaped melt support boat (10) together with the substrate (9). The melt-supporting boat (10) has rectangular melt-holding ports (11) at regular intervals, and the substrate-holding / transporting body ( 8) Melt support boat (1
Intermittent slide movement with respect to 0).

The melt holding port (11) of the melt supporting boat (10)
A metal block (13) of the same shape is supplied to the substrate (9)
Listed above. A certain amount of granular dopant (4) such as tellurium or tin is supplied from above the metal block (13) together with a crystalline metal material such as gallium arsenide (not shown). Plural kinds of dopants (4) are classified and supplied to the plural melt holding ports (11) of the melt supporting boat (10).

As shown in FIG. 6, the substrate holding and transporting body (8)
And the melt support boat (10) is heated in the quartz tube (12) in a hydrogen atmosphere. When the metal block (13) is heated in the quartz tube (12) to a desired temperature of 600 ° C. to 850 ° C., the temperature is maintained for several hours. During this time the metal block (1
The dopant (4) is dissolved in the molten metal [solvent] in which 3) is molten until it is saturated. When this molten metal is brought into contact with the substrate (9) and gradually cooled in the quartz tube (12) at 0.3 to 1.0 ° C./minute, a solid phase begins to precipitate in the liquid phase at a certain temperature, and the solid phase begins on the substrate (9). The crystal grows epitaxially at.

The substrate holding carrier (8) is intermittently slid with respect to the melt supporting boat (10) to move the substrates (9) below the respective melt holding ports (11) in order. In 9), p-type and n-type semiconductor regions are formed in the multilayer.

[0008]

Since the metal block (13) for liquid phase epitaxial growth is required to have a high purity, a product obtained by casting a highly purified metal in a mold is used.

However, such a cast metal block (13) has a substantially semi-cylindrical shape whose entire surface is curved due to surface tension, as shown in (a) and (b) of FIG. 7. On the other hand, the dopant (4) supplied onto the metal block (13) housed in the melt holding port (11) of the melt supporting boat (10) is a particle having a diameter of about 1 mm.

As a result, when the dopant (4) is supplied onto the metal block (13) with tweezers or the like, the dopant (4) slides down on the curved surface of the metal block (13), and the metal block (13). ) May be concentrated in the peripheral area. When the metal block (13) is heated and melted in such a dopant distribution state, a non-negligible difference occurs in the dopant concentration between the peripheral portion and the central portion of the molten metal, and this difference deteriorates the quality of the liquid phase epitaxial growth substrate. It is a factor.

Therefore, it is an object of the present invention to provide a metal block for liquid phase epitaxial growth and a method for manufacturing the same for enhancing the uniformity of the dopant concentration and stabilizing the liquid phase epitaxial growth in quality. ..

[0012]

According to the present invention, a dopant accommodating portion for accommodating and retaining a granular dopant is formed on the surface of a liquid phase epitaxial growth metal block.
The above object is achieved.

The dopant storage portion on the surface of the metal block is
It is desirable to manufacture the metal block that it is a concave portion partially formed on the surface of the metal block.

The metal block is preferably cast by pouring a low melting point high purity metal into a mold having a convex portion or a concave portion on the bottom surface.

[0015]

[Function] Even if the metal block is a cast semi-cylindrical shape, if the granular dopant is stored in the dopant storage portion such as a recess formed in the surface of the metal block, the dopant is transferred from the surface of the metal block to the peripheral portion. There is no need to worry about unwillingness to disperse. Therefore, with proper setting of the position and shape of the dopant accommodating portion, the dopant will always diffuse from the fixed position into the molten metal block, and it will be easy to make the dopant concentration distribution in the solvent uniform.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a metal block (1) which is an embodiment of the present invention, and FIG. 2 shows an embodiment of a mold (5) for casting the metal block (1).

The metal block (1) of FIG. 1 is formed by casting a metal such as indium or gallium having a low melting point and high purity for liquid phase epitaxial growth into a substantially rectangular shape. The metal block (1) has a substantially semicylindrical shape as a whole and is characterized by having a dopant accommodating portion (2) on its surface.

The dopant storage portion (2) is a portion for storing and holding a fixed amount of granular dopant (4), for example, a recess (3) partially formed on the curved surface of the metal block (1).
Is. The concave portion (3) is a substantially circular depression, and the diameter and depth thereof are set to a size in which a desired amount of the granular dopant (4) can be stably stored, as shown in FIG.

The number of recesses (3) in one metal block (1) is set according to the size of the metal block (1). For example, the metal block (1) shown in FIG. 1 has a relatively large size, and in this case, the recesses (3) are formed in the central portion of the surface and the five corners of the four corners which are evenly distributed. Further, in the rectangular metal block (1 ′) having a relatively small size as shown in FIG. 3, three recesses (3) are formed in a line on the surface thereof.

The metal block (1) of FIG. 1 may be cast with the mold (5) of FIG. The mold (5) has a convex portion (7) at the bottom of the opening (6) that matches the outer shape of the metal block (1).
Is formed. The convex portion (7) is formed by five convex portions (7a) partially protruding from the bottom of the opening (6). When the highly purified refined molten metal is poured into the opening (6) and is cooled and hardened, a substantially semi-cylindrical metal block (1) having a concave portion (3) formed in the convex portion (7a) is cast. It

When a concave portion is formed on the surface of a cast metal block with a tool, the metal block is contaminated with impurities when the concave portion is processed by the tool, and high purity cannot be maintained. If the casting is performed in (5), there is no concern that the purity will decrease, and the recess (3) is formed at the same time as casting, which is advantageous in the manufacturing process.

Conventional equipment is applied to a liquid phase epitaxial growth apparatus such as a laser diode using the metal block (1).

The mold (5) may be provided with a recess at the bottom of the opening (6) and the recess may form a surface other than the projection of the metal block.

For example, as shown in FIG. 4, a substrate holding carrier (8) and a melt supporting boat (10) are combined, and a metal block (1) is attached to a melt holding port (11) of the melt supporting boat (10). ) Is stored and a certain amount of granular dopant (4) is supplied from above. The dopant (4) is sandwiched between tweezers, for example, and is supplied only to the concave portion (3) of the metal block (1).
A plurality of dopants (4) of the same type or a plurality of dopants (4) may be supplied to one recess (3).

Dopant (4) supplied to the recess (3)
Does not jump out from the concave portion (3) even if some vibration is applied, and is stably held at a fixed position in the concave portion (3).

The substrate holding carrier (8) and the melt supporting boat (10) are housed in a quartz tube (12), heated as in the conventional case, and then slowly cooled. 9) The desired liquid phase epitaxial growth is performed.

When the metal block (1) is melted, the dopants (4) contained in the five uniformly distributed recesses (3) on the surface of the metal block (1) become the recesses (3).
Diffuses into the molten metal [solvent] from the fixed position. Recess (3)
Are dispersed evenly over the entire surface of the metal block (1), so that the dopant (4) diffuses evenly throughout the molten metal of the metal block (1). As a result, the distribution of the dopant concentration in the molten metal becomes uniform, and the liquid phase epitaxial growth is uniformly performed on the substrate (9).

It should be noted that the dopant accommodating portion of the cast metal block is not limited to the concave portion as described above. May be stored.

[0029]

According to the present invention, when a granular dopant is accommodated and held in the dopant accommodating portion formed on the surface of the cast metal block for liquid phase epitaxial growth and the metal block is heated and melted, the molten metal is melted. The dopant will always diffuse from the fixed position in the proper direction, the dopant concentration distribution in the molten metal will be uniform, and stable liquid-phase epitaxial growth will be possible. It has the effect of improving product quality and yield.

Further, by casting the metal block in a mold having a convex portion or a concave portion formed on the bottom, the metal block can be manufactured together with the dopant accommodating portion on the surface thereof in one step, and it is excellent in quality and has a low melting point and a high purity. There is an effect that a metal block for liquid phase epitaxial growth can be easily manufactured.

[Brief description of drawings]

FIG. 1 shows an embodiment of a metal block according to the present invention, in which (a) is a plan view and (b) is a cross-sectional view taken along the line AA.

FIG. 2 is a sectional view of a mold for casting the metal block of FIG.

FIG. 3 shows another embodiment of the metal block according to the present invention, in which (a) is a plan view and (b) is a cross-sectional view taken along line BB.

4 is a partial sectional view of a liquid phase epitaxial growth apparatus using the metal block of FIG.

FIG. 5 is a partial cross-sectional view of a conventional liquid phase epitaxial growth apparatus using a metal block when supplying a dopant.

6 is a partial cross-sectional view of the apparatus of FIG. 5 during a liquid phase epitaxial growth operation.

FIG. 7 shows a conventional metal block for liquid phase epitaxial growth, in which (a) is a plan view and (b) is a sectional view taken along line CC.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal block 2 Dopant accommodating part 3 Recessed part 4 Dopant 5 Template 6 Opening part 7 Convex part

Claims (3)

[Claims] 1. A metal block for liquid phase epitaxial growth, comprising a dopant accommodating portion for accommodating and retaining a granular dopant on its surface. 2. The metal block for liquid phase epitaxial growth according to claim 1, wherein the dopant accommodating portion is a concave portion partially formed. 3. A method for producing a metal block for liquid phase epitaxial growth, which comprises casting a high-purity metal by pouring into a metal block casting opening of a mold having a convex portion or a concave portion formed on the bottom surface.