JPS61261293A - Boat for liquid-phase epitaxial growth - Google Patents

Abstract

PURPOSE:The titled board capable of pulling clearly melt for growth and of raising reproducibility of a vapor-pressure controlling atmosphere, being provided with a movable piece and a close type cover. CONSTITUTION:The slider 4 is slid from the right side in the arrow direction, the substrate crystal 2 is brought into contact with the melt 5 for washing, the surface of the substrate crystal 2 is washed, the slider 4 is further moved in the arrow direction, the substrate crystal 2 is brought into contact with the melt 7 for growing and subjected to epitaxial growth. When the slider 4 is transferred in the left direction, the melt 7 for growing is pulled by the movable piece 13, the substrate crystal 2 is put in the empty chamber 11 and cooled. Since the empty chamber 11 is connected to the vapor-pressure control material chamber 10, it is kept in a vapor-pressure controlling atmosphere during cooling. Since the cover 14 is fixed to the slider 4 and a closed structure is formed, this process has improved reproducibility of the vapor-pressure control atmosphere. A higher-quality epitaxial layer is obtained since a melt composition during growth is kept in higher stability than a case where the cover 14 is not set.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a boat used for liquid phase epitaxial growth of semiconductor crystals.

[Conventional technology]

Conventionally, a boat used for semiconductor liquid phase epitaxial growth of a compound such as HgneyxcdxTe has a substrate that holds a substrate crystal, a slider that covers the substrate crystal and is slidably provided on the substrate, and a slider that is mounted on the substrate crystal. Boats have been proposed (e.g., J, Electronic
Materials, Dan-133 (1982)).

In the conventional boat described above, the substrate crystal is placed on the substrate outside the slider before epitaxial growth begins, and the slider is slid during growth, and the surface of the substrate crystal is lightly cleaned with cleaning melt as necessary. rear,
Epitaxial growth was performed by coating the substrate crystal with the growth melt, and when the growth was completed, it was immediately pulled out from inside the slider and cooled. In addition, in order to prevent volatilization of components that easily sublimate, a vapor pressure control material is coexisting in the slider to maintain the stoichiometry of the grown epitaxial layer within a desired range. the result,
During growth, crystal growth is performed under vapor pressure control.

[Problem that the invention seeks to solve]

However, in conventional boats such as those mentioned above,
Since the growth melt is filled in a growth melt chamber surrounded by the partition walls of the slider, the melt is not easily cut by the partition walls of the slider, and the growth melt often remains on the substrate crystal, which is a problem that prevents high-quality epitaxial growth. This made it difficult to obtain crystals.

The slider and lid fit together, but the degree of sealing differs depending on the boat, and as a result, it is difficult to reproduce the atmosphere for vapor pressure control, which causes variations in the characteristics of the grown crystals. was.

Furthermore, as the substrate crystal is pulled out of the vapor pressure controlled atmosphere at the end of growth, unexpected deviations in stoichiometry often occur during this period. Moreover, the deviation between this period strongly depends on the cooling rate and the partial pressure in the atmosphere, but it is extremely difficult to maintain a vapor pressure controlled atmosphere from the end of growth until the sample is cooled and taken out. There were also problems such as significant differences due to differences in workers and lack of reproducibility.

This invention was made to solve the above-mentioned problems, and provides a boat for liquid phase epitaxial growth that can cleanly sweep the growing melt from above the substrate crystal and improve the reproducibility of the vapor pressure controlled atmosphere. The purpose is to

In addition to the above object, another object of the present invention is to obtain a boat for liquid phase epitaxial growth which can be cooled in a vapor pressure controlled atmosphere after completion of epitaxial growth to prevent deviation of stoichiometry.

[Means for solving problems]

The boat for liquid phase epitaxial growth according to this invention is-
A substrate for holding a substrate crystal, a slider that covers the substrate crystal and is slidably provided on the substrate, a growth melt chamber provided at a position where the slider passes over the substrate crystal, and a growth melt chamber for the growth melt chamber. It is equipped with a movable piece provided on the partition wall so as to come into contact with the substrate crystal under its own weight, a lid that hermetically covers the top of the slider, and a vapor pressure control material chamber provided within the slider.

A boat for liquid phase epitaxial growth according to another aspect of the present invention includes a substrate that holds a substrate crystal, a slider that covers the substrate crystal and is slidably provided on the substrate, and a slider that passes over the substrate crystal of the slider. a growth melt chamber provided at a position, a movable piece provided on the partition wall of the growth melt chamber so as to contact the substrate crystal under its own weight, a lid that tightly covers the top of the slider, and a lid provided inside the slider. In addition to the vapor pressure control material chamber, the chamber is further provided with an empty chamber communicating with the vapor pressure control material chamber for cooling the substrate crystal after epitaxial growth.

[For production]

In the boat for liquid phase epitaxial growth according to the present invention, the substrate crystal is held on the substrate and the slider is slid, the substrate crystal is brought into contact with the growth melt to perform epitaxial growth, and the slider is further slid to move the substrate crystal onto the substrate crystal. After sweeping with the movable piece, the substrate crystal is cooled. At this time, since the lid has a closed structure, the reproducibility of the vapor pressure controlled atmosphere can be improved.

In a boat for liquid phase epitaxial growth according to another aspect of the present invention, the substrate crystal is cooled in a vacant room after epitaxial growth as described above. At this time, since the empty chamber is under a vapor pressure controlled atmosphere, deviations in stoichiometry are prevented.

〔Example〕

FIG. 1 is a sectional view showing a boat for liquid phase epitaxial growth according to an embodiment of the present invention.
is a substrate, on the upper surface of which a substrate crystal chamber (3) for holding a substrate crystal (2) is provided. A slider (4) is provided to cover the substrate crystal chamber (3) and to be slidable over the substrate (1). A cleaning melt chamber (6) in which the slider (4) passes over the substrate crystal chamber (3) is filled with cleaning melt (5) sequentially from one end side.
), a growth melt chamber (8) filled with growth melt (7)
), a vapor pressure control material chamber (10) filled with a vapor pressure control material (9), and a vacant space (11) are partitioned by a partition wall (12). A movable piece (13) is installed on the partition wall (12) between the growth melt chamber (8) and the vapor pressure control material chamber (1o).
is provided so that it comes into contact with the substrate (1) and the substrate crystal (2) by its own weight without forming a gap. A lid (14) is fixed to the top of the slider (4) to form a sealed structure.

The slider (4) slides in the direction of the arrow to perform epitaxial growth, and FIG. 1 shows the state at the time of cooling after growth. The movable piece (13) is a porous material, a crystal material,
It can be made of any amorphous material, and does not need to be the same material as graphite or boron nitride (BN), which are boat materials, as long as it is a high-density material that has excellent workability, high heat resistance, and corrosion resistance. For example, crystalline materials such as sapphire, ceramic materials such as alumina, metallic materials such as platinum, and even glass materials such as grady carbon can be used.

In the above configuration, to perform epitaxial growth,
Place the slider (4) to the right of the diagram.

Slide the slider (4) in the direction of the arrow from the position where the substrate crystal (2) is on the left side of the slider (4), and first contact it with the cleaning melt (5) to clean the surface of the substrate crystal (2). Next, the slider (4) is further moved in the direction of the arrow to bring the substrate crystal (2) into contact with the growth melt (2) to perform epitaxial growth.

When the slider (4) is further moved, the growth melt is swept by the movable piece (13), the substrate crystal (2) enters the empty chamber (11) and is cooled, and the air (11) is transferred to the vapor pressure control material chamber. (lO), so a vapor pressure controlled atmosphere is maintained during cooling.

In conventional boats, there is a small gap between the slider (4) and the substrate (1), and since the boat is made of a material such as graphite, the end face of the bulkhead (12) of the slider (4) is sufficiently spaced. Because it was not smooth, when moving the slider (4) to sweep the growth melt from the surface of the growing crystal, it was not possible to sweep the growth melt completely, and the growth melt often remained and When the viscosity of the melt is low.

Sweeping was more difficult when the wettability between the growth melt and the substrate crystal (2) was good; however, in the present invention, the movable piece (1)
3) comes into contact with the growing crystal surface due to its own weight.

There are no gaps smaller than the partition wall (12) and the sweeping of the growing melt is complete. This movable piece (13) moves over the substrate crystal (2) while contacting the substrate (1), so
There is no need to worry about damaging the grown epitaxial layer.

Such a movable piece (13) not only improves melt cutting and completely eliminates residual melt, but also has the following good effects. That is, when the melt breaks, unnecessary stirring of the melt is less likely to occur, and as a result, the meltback (remelting) of the grown layer caused by non-uniformity of the melt components, which conventionally tends to occur, can be largely avoided.

Furthermore, in the above device, the lid (14) is fixed to the slider (4) and has a sealed structure, so the reproducibility of the vapor pressure controlled atmosphere is excellent. Since the lid (14) effectively prevents the volatilization of volatile or high vapor pressure components, the melt composition during growth is kept more stable than without the lid (14), resulting in high quality. An epitaxial layer is obtained.

Furthermore, conventional boats are not provided with a vacant chamber (11), but a vacant chamber (11) is provided inside the slider (4).

When the grown substrate crystal (2) is cooled in the empty space (11), the partial pressure from the vapor pressure control material (9) is maintained in the space even if the cooling is performed quickly. During cooling, the characteristics of the grown crystal do not change in particular, and deviations in stoichiometry can be prevented.

It is clear that the wettability between the movable piece (13) and the growth melt (7) greatly depends on the properties of the movable piece (13), and it is necessary to improve the wettability in order to eliminate residual melt. . For this purpose, it is effective to increase the contact area between the movable piece (13) and the melt, and it is useful to use porous materials such as various highly porous ceramic materials.

Another method for improving wettability is to apply a film of an element that reacts with the melt to form a compound on the bottom and side surfaces of the movable piece (13), that is, the surface that comes into contact with the melt. For example, in the case of tellurium melt, the metals include zinc, cadmium,
Gallium, indium, tin, lead, antimony, bismuth, etc. are suitable;
By contacting with molten tellurium at a temperature of 00° C. or higher, telluride is easily and quickly produced, so the wettability with the melt is greatly improved by reaction. Also, the movable piece (13
) may be attached with a compound film having the melt material as its constituent element.

For example, in the case of tellurium melt, ZnTe, CdTe,
Gallium telluride (GaTe, Ga2Te3.Ga
3Te2. GaTe5), indium telluride (InT
e, In2Te3, In2Ta.

In2Te5), 5nTe, PbTe, antimony telluride, bismuth telluride (BiTe, Bi2Te,
Bi2Ta3) etc. are suitable. In order to attach a film of these elements or a compound film to the skeleton base material of the movable piece (13), an optimal means such as a binder, vacuum evaporation, chemical transport, plating, etc. can be used. Movable piece to be attached (1
The skeletal base material in 3) is not limited to a smooth material, but if it is applied to a porous material, the surface area will increase, resulting in even better results. Furthermore, if the movable piece (13) is provided with many through holes in the vertical direction, the wettability can be further improved due to capillary action.

ZnTe and CdTe are crystalline materials with good cleavability.
.

A layered compound such as gallium telluride can be used as it is as the movable piece (13) by adjusting the dimensions for cleavage. When using a crystal plate, better results can be obtained by mirror polishing.

The end face shape of the movable piece (13) does not need to be flat; for example, in order to effectively sweep the growth melt, the end face can be shaped like a blade, depending on the physical properties of the growth melt, etc. The optimum shape can be selected by Further, the number of movable pieces (13) is not limited to one, and can be increased as necessary.

2nd WI is a sectional view showing a part of another embodiment, and FIG. 3 is an AA sectional view thereof. In this example, the slider (4
) and the lid (14) have an integral structure.

The airtightness is even higher, and the reproducibility of the vapor pressure controlled atmosphere is even higher.

FIG. 4 is a sectional view showing another embodiment. In this embodiment, the slider (4) and the lid (14) are connected by a threaded portion (15). By sealing with the threaded portion (15), the degree of sealing inside the slider (4) is improved, its reproducibility is improved, and the lid (14) can be easily attached and detached. In this case, in order to connect with the threaded portion (15), the opening of the slider (4) and the outer circumference of the lid (14) need to be circular. Figure 4 shows an example with one lid (14), but if the boat is large, the lid (14) will also be large and it may be difficult to store it in the core tube. In such a case, increasing the diameter of the lid can be avoided by dividing the lid (14) and using several small circular lids. In such a case, it is desirable to consider dividing a portion of the slider in accordance with the division of the lid so as to be able to control the steam pressure and to prevent the degree of sealing from becoming poor.

FIG. 5 is a sectional view showing still another embodiment.

In this embodiment, the slider (4) and the lid (14) are integrally formed, and a vapor pressure control material chamber (10) filled with a vapor pressure control material (9) is provided on the substrate (1).

Further, another cavity (16) is provided at the end opposite to the cavity (11) in the slider (4), that is, between the cleaning melt chamber (6) and the end wall. It communicates with the vapor pressure control material chamber (10). The empty chamber (16) is where the substrate crystal (2) is located before the start of growth, thereby allowing the substrate crystal (2) to be placed on the slider (4) before epitaxial growth.
In other words, it can be introduced into a vapor pressure controlled atmosphere without being installed outside the vapor pressure controlled atmosphere, and deviations in stoichiometry before the start of growth can be prevented.

FIG. 6 is a sectional view showing still another embodiment, FIG. 7 is a plan view of a part of the substrate, and FIG. 8 is a BB sectional view thereof. In this embodiment, each partition wall (12) and lid (14) of the slider (4) are integrally formed without any gap,
A removable lid (17) is screwed onto the lid (14) with screws (18). Also, the substrate crystal chamber (3) of the substrate (1)
A bypass groove (19) that does not pass along a straight line connecting both chambers is provided between the vapor pressure control material chamber (1o) and the vapor pressure control material chamber (1o). The spacing between the two chambers is such that when the substrate crystal chamber (3) faces the vacant chamber (16), the vapor pressure control material chamber (1o) faces the vacant chamber (11), and both chambers face the vacant chamber (11). They are now facing each other.

By selecting the position of the bypass groove (19) in this way, the partial pressure of the vapor pressure control material (9) can be efficiently adjusted to the substrate crystal (2).
), and at this time, it is possible to prevent the cleaning melt (5) and growth melt (7) from flowing into the bypass groove (19). Also when cooling.

The grown substrate crystal (2) is stored in the cavity (11) together with the vapor pressure control material (9), so that it can be maintained in a vapor pressure controlled atmosphere. Such a bypass groove (19
) is particularly effective in the case of a closed type slider in which the upper part of the partition wall (12) does not pass through, and can efficiently control the steam pressure, but it may also be provided in the case of FIG.

Example 1 When "cHgt-xTe is grown on a CdTa (m) substrate by liquid phase epitaxial growth, the boat shown in FIG. 5 is used, tellurium melt is used as the growth melt (7), and the movable piece (13) An epitaxially grown film with no residual melt was obtained by using a carbon plate with a 20 μm metal cadmium film deposited on the entire surface.

Example 2 The same results as in Example 1 were obtained by using the boat shown in FIG. 6 and using a 10 μm metal zinc film deposited instead of the metal cadmium film.

Example 3 Similar results were obtained in Example 1 by using the boat shown in FIG. 6 and using a CdTe film made of 30 μm of 0 μm instead of the metal cadmium film.

Example 4 In Example 1, a ZnTe film 5 was used instead of the CdTa film.
An epitaxially grown film with no residual melt was obtained using a film deposited with μ.

Example 5 In Example 1, an epitaxially grown film with no residual melt was obtained by using a porous carbon movable piece (13) with a 10μ vapor-deposited film of Cd on the entire surface.

Example 6 In Example 1, the movable piece (13) has a thickness of III
When a CdTe plate of I was used, an epitaxially grown film with no residual melt was obtained.

Example 7 In Example 1, when a ZnTe plate of the same thickness was used instead of the CdTe plate as the movable piece (13), an epitaxially grown film without residual melt was obtained.

〔Effect of the invention〕

According to the present invention, since a movable piece is provided and the lid is of a closed type, it is possible to cleanly sweep the growth melt from above the substrate crystal, and the reproducibility of the vapor pressure controlled atmosphere can be improved.

According to another invention of the present invention, in addition to the above effects,
After the epitaxial growth is completed, it is cooled in a vapor pressure controlled atmosphere to prevent deviations in stoichiometry.

[Brief explanation of the drawing]

FIG. 1 and FIGS. 4 to 6 are sectional views showing another embodiment of the present invention, FIG. 2 is a sectional view showing a part of the other embodiment, and FIG. 7 is a plan view of a part of the substrate shown in FIG. 6, and FIG. 8 is a sectional view taken along line B--B. In each figure, the same reference numerals indicate the same or corresponding parts, (1)
is the substrate, (2) is the substrate crystal, (4) is the slider, (5
) is a cleaning melt, (7) is a growth melt, (8) is a growth melt chamber, (9) is a vapor pressure control material, (10) is a vapor pressure control material chamber, (11) and (16) are Vacant room, (13
) is a movable piece, and (14) is a lid.

Claims (8)

[Claims] (1) a substrate that holds a substrate crystal; a slider that covers the substrate crystal and is slidably provided on the substrate;
A growth melt chamber provided at a position where the slider passes over the substrate crystal, a movable piece provided on a partition wall of the growth melt chamber so as to come into contact with the substrate crystal under its own weight, and an upper portion of the slider. 1. A boat for liquid phase epitaxial growth, comprising: a lid that hermetically covers the slider; and a vapor pressure control material chamber provided within the slider. (2) The boat for liquid phase epitaxial growth according to claim 1, wherein the movable piece is made of a porous material, a crystalline material, or an amorphous material. (3) The movable piece is formed from a skeletal base material, an element that forms a compound with the melt material or a compound containing the melt material as a constituent element, and a binder, or 2. A boat for liquid phase epitaxial growth according to item 2. (4) The boat for liquid phase epitaxial growth according to any one of claims 1 to 3, wherein the lid is integrally constructed with the slider or is screwed. (5) a substrate that holds a substrate crystal; a slider that covers the substrate crystal and is slidably provided on the substrate;
A growth melt chamber provided at a position where the slider passes over the substrate crystal, a movable piece provided on a partition wall of the growth melt chamber so as to come into contact with the substrate crystal under its own weight, and an upper portion of the slider. a lid that hermetically covers the slider, a vapor pressure control material chamber provided in the slider, and a vacant chamber that communicates with the vapor pressure control material chamber and cools the substrate crystal after epitaxial growth. A boat for liquid phase epitaxial growth. (6) The boat for liquid phase epitaxial growth according to claim 5, wherein the movable piece is made of a porous material, a crystalline material, or an amorphous material. (7) The movable piece is formed from a skeletal base material, an element that forms a compound with the melt material or a compound containing the melt material as a constituent element, and a binder. The boat for liquid phase epitaxial growth according to item 6. (8) The boat for liquid phase epitaxial growth according to any one of claims 5 to 7, wherein the lid is integrally constructed with the slider or is screwed.