JP2000182978A - Method and apparatus for liquid phase epitaxial growth - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress dissociation of a semiconductor single crystal substrate in a high temp. by aerating this substrate composed of a metal and an element more volatile than the metal in a gas atmosphere composed of an easily volatile element, and contacting and chilling it with a semiconductor growing solution composed of a metal and an easily volatile element. SOLUTION: A single crystal substrate 2 composed of a metal e.g. Ga and an more volatile element e.g. P than the metal is set at a room temp. in a growing chamber 1a, a specified quantity of solid Ga and a quantity of GaP enough to supersaturate in Ga are housed in a growing GaP solution housing 6a, the growing chamber 1a and the GaP soln. housing 6a are held in an H atmosphere and heated at the same time to prepare a growing GaP solution 6 of GaP dissolved in the Ga melt, and this soln. 6 is again heated to melt back and then cooled to form an epitaxial layer on the GaP single crystal substrate 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for liquid phase epitaxial growth, and more particularly to the manufacture of a device such as a high-brightness GaP (gallium-phosphorus) light-emitting diode used for a light source of a display panel. The present invention relates to a liquid phase epitaxial growth method and apparatus suitably used in the above step.

[0002]

2. Description of the Related Art For liquid phase epitaxial growth, GaP
The manufacture of a light emitting diode will be described as an example. Red and green light emitting diodes are known as GaP light emitting diodes, but N (nitrogen) doped Ga is used for outdoor display.
A green light emitting diode made of P (N: GaP) is mainly used. As a method for increasing the luminance of a green N: GaP light-emitting diode, it is important to improve the crystal quality because the light-emitting mechanism is an indirect transition, and in particular, the first is to improve the crystallinity near the PN junction. Can be

At present, in liquid phase epitaxial growth for GaP light emitting diodes, crystal growth is performed on several tens of GaP single crystal substrates by one epitaxial growth. That is, GaP is added to the growth chamber of the liquid phase epitaxial growth apparatus.
Dozens of single crystal substrates are held in parallel, and Ga and GaP are housed in the semiconductor solution housing chamber next to them. Then, the growth chamber and the semiconductor solution storage chamber are heated to a high temperature (about 1000 ° C.) to grow Ga and GaP in the semiconductor solution storage chamber by dissolving GaP in a molten Ga melt to a supersaturated state. Then, the GaP solution is introduced into a growth chamber and cooled to grow a GaP crystal on a GaP single crystal substrate.

In this case, the GaP single crystal substrate is set in the growth chamber before heating the growth chamber.
Exposure to high temperatures of about 1000 ° C. The dissociation temperature of GaP is about 650 ° C.
P (phosphorus) dissociates from the aP single crystal substrate, causing damage to the surface of the GaP single crystal substrate.

Therefore, usually, the damage to the crystallinity of the epitaxially grown layer is reduced by removing the damaged layer by melt back before the epitaxial growth.

[0006]

However, GaP
If the amount of melt back is increased to completely remove the damaged layer on the surface of the single crystal substrate, a dopant such as oxygen contained in the GaP single crystal substrate may be removed from the growth GaP.
Contaminating the GaP solution for growth by mixing into the solution. Further, there is a disadvantage that the carrier concentration in the epitaxial layer becomes unstable due to the influence of the dopant in the GaP single crystal substrate.

The present invention has been made in view of such circumstances. For example, if an epitaxial growth layer is formed on a GaP single crystal substrate in a liquid phase epitaxial growth chamber, the GaP single crystal substrate may be replaced with P (phosphorus). The present invention provides a liquid phase epitaxial growth method and apparatus which suppresses dissociation of a semiconductor single crystal substrate at a high temperature by aerating in a gas atmosphere consisting of:

[0008]

According to the present invention, a semiconductor single crystal substrate comprising a metal (s) and an element more volatile than the metals (s) is provided in a liquid phase epitaxial growth chamber. After aeration (exposure to air) in a gaseous atmosphere made of an element, it is brought into contact with a semiconductor growth solution containing the metal (s) and the volatile element and cooled from a predetermined temperature. This is a liquid phase epitaxial growth method characterized by forming an epitaxial layer on a semiconductor single crystal substrate.

The present invention is also directed to a substrate holding means for holding a semiconductor single crystal substrate comprising a metal (s) and an element more volatile than the metal (s); A growth solution storage unit for storing a semiconductor growth solution comprising: a heating unit; a contact unit configured to contact the semiconductor single crystal substrate with the semiconductor growth solution; a cooling unit; and a cooling unit; And a solution accommodating section for accommodating the same solution as the semiconductor growth solution.

According to the present invention, the semiconductor single crystal substrate composed of the metal and the element more volatile than the metal is aerated in the gas atmosphere composed of the more volatile element. And a damage layer on the surface of the semiconductor single crystal substrate can be reduced. In addition, since the amount of melt back can be reduced, the carrier concentration of the epitaxial growth layer can be stabilized, and the influence of impurities existing inside the semiconductor single crystal substrate can be suppressed. A light emitting diode can be manufactured.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The liquid phase epitaxial growth method of the present invention can be applied to a liquid phase epitaxial growth apparatus using any method such as a tipping method (tilting method), a dipping method, and a slide boat method. is there.

In the present invention, the semiconductor single crystal substrate is
What is necessary is just to consist of a metal (class) and an element more volatile than the metal (class), and the contained metal may be singular or plural.

That is, the semiconductor single crystal substrate of the present invention comprises:
A single metal (eg, Ga, In, etc.) and an element that is more volatile (easily volatilized) than that metal (eg, As, P, etc.)
And a plurality of metals (eg, Ga
In, AlGaIn, etc.) and a semiconductor single crystal substrate made of an element more volatile than those metals (eg, As, P, etc.).

Specifically, as a semiconductor single crystal substrate,
GaP single crystal substrate, GaAs single crystal substrate, InP single crystal substrate, GaSb single crystal substrate, GaInP single crystal substrate, A
Various single crystal substrates such as an lGaInP single crystal substrate can be used.

In the present invention, aeration of a semiconductor single crystal substrate in a gaseous atmosphere composed of a volatile element is performed as follows:
It is desirable that the same solution as the semiconductor growth solution is arranged below the semiconductor single crystal substrate and the liquid phase epitaxial growth chamber is heated to a predetermined temperature.

For example, a GaP single crystal substrate can be used as a semiconductor single crystal substrate, and a GaP solution in which GaP is dissolved in a melt of Ga (gallium) can be used as a semiconductor growth solution. When a single crystal substrate is used, P (phosphorus) is an element more volatile than Ga, so that a GaP single crystal substrate can be aerated in an appropriate P (phosphorus) gas atmosphere.

Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. Note that the present invention is not limited to this.

FIG. 1 is an explanatory view showing the configuration of an embodiment of a liquid phase epitaxial growth apparatus according to the present invention. This liquid phase epitaxial growth apparatus is a horizontal furnace type substrate rotating type carbon boat for epitaxial growth, and (b)
Shows a front view, and (a) shows a side view. In the present embodiment, liquid phase epitaxial growth applied when manufacturing a green GaP (gallium / phosphorus) light emitting diode will be described.

In the figure, 1 is a main body of a liquid phase epitaxial growth apparatus, 1a is a growth chamber, 2 is a GaP single crystal substrate held in the growth chamber 1a, 3 is a jig for holding a substrate made of carbon, and 4 is a substrate rotating jig. Reference numeral 5 denotes an atmosphere forming solution storage unit, 6 denotes a growth GaP solution, and 6a denotes a growth GaP solution storage unit.

The GaP single crystal substrate 2 is held by three substrate holding jigs 3 and a plurality of the substrates are set. In this embodiment, six sheets are set at the same time. The GaP single crystal substrate 2 can be rotated together with the substrate holding jig 3 by the substrate rotating jig 4 in the direction of the arrow A in the drawing or in the opposite direction.

In forming the epitaxial growth layer,
First, the GaP single crystal substrate 2 is set in the growth chamber 1a at room temperature, and a predetermined amount of solid Ga (gallium) and only a supersaturated Ga in the Ga are placed in the growth GaP solution accommodating portion 6a. It contains a sufficient amount of GaP. Ga
An N-type dopant, for example, tellurium is added to P.

Then, the growth chamber 1a and the GaP solution container 6
and a while heating in a hydrogen atmosphere. A known heating device is used for heating. Thereby, the Ga for growth
Ga and GaP accommodated in the P solution accommodating portion 6a are melted into a liquid state, and become a growth GaP solution 6 in which GaP is dissolved in a melt of Ga. The GaP solution 6 for growth is heated to about 1000 ° C. and kept at a constant temperature, thereby dissolving GaP in the melt of Ga to a supersaturated state.

GaP solution 6 for growth and GaP single crystal substrate 2
Is kept at a constant temperature of about 1000 ° C., the liquid level is raised by pressing the growth GaP solution 6 from the right in the figure with a jig (not shown), and the growth chamber 1a is indicated by an arrow B in the figure. Introduce within. As a device for pressing the growth GaP solution 6 by a jig, a known device is used. Above the boundary between the growth chamber 1a and the growth GaP solution accommodating section 6a, a growth source inlet (not shown) provided with a mesh-like filtration device is provided. The solution is filtered through the growth source inlet and introduced into the growth chamber 1a.

After the growth GaP solution 6 is further heated and melt-backed, the well-known cooling device is used.
The GaP solution for growth 6 is cooled to form an epitaxial layer on the GaP single crystal substrate 2. The GaP single crystal substrate 2
During cooling, the substrate is rotated by the substrate rotating jig 4 in the direction of arrow A shown in FIG.

In the liquid phase epitaxial growth for the GaP light emitting diode, a P-type layer is formed by supplying a vaporized P-type dopant such as Zn (zinc) to the growth GaP solution 6 during the crystal growth process. Therefore, the upper part of the growth chamber 1a is open.

An atmosphere forming solution is stored in an atmosphere forming solution storage section 5 provided below the growth chamber 1a. In this embodiment, the growth Ga is used as the atmosphere forming solution.
The same as P solution 6 was used. In addition, G of these solutions
The aP concentration depends on the temperature, and since the growth chamber 1a is at the same temperature as the growth GaP solution accommodating portion 6a, the atmosphere forming solution changes at the same GaP concentration as the growth GaP solution 6.

FIG. 2 shows a temperature program for crystal growth of the present liquid phase epitaxial growth apparatus. As described above, the growth GaP solution 6 to which the N-type dopant is added is
Saturate at 000 ° C. Next, the GaP solution for growth 6
Is introduced into the growth chamber 1a, and Ga is added to the GaP solution 6 for growth.
The P single crystal substrate 2 is immersed, and the temperature is further increased by about 5 ° C. to melt back the GaP single crystal substrate 2. The damage layer on the surface of the GaP single crystal substrate 2 is removed by this melt back.

Thereafter, the N-type GaP epitaxial layer is formed on the GaP single crystal substrate 2 by gradually cooling it to 900 ° C. at a constant cooling rate, for example, 0.5 ° C./min. 90
The temperature was maintained at 0 ° C. for about 60 minutes. At this time, vaporized Zn (zinc) was supplied onto the GaP solution 6 for growth in order to add a P-type dopant.
(Zinc). Thereafter, it is gradually cooled again at a constant cooling rate, for example, 1.0 ° C./min, and is grown to 850 ° C. During this time, a constant amount of Zn (zinc) is continuously supplied onto the growth GaP solution 6 to suppress vaporization from the growth GaP solution 6.

At this temperature of 850 ° C., since the crystal growth is almost stopped, the GaP single crystal substrate 2 is taken out while the GaP single crystal substrate 2 is immersed in the growth GaP solution 6 and the temperature is lowered.

After obtaining a wafer for a GaP light emitting diode on which a GaP crystal is grown by epitaxial growth on a GaP single crystal substrate 2, a grooving process with a diameter of 600 μm is performed from the surface of the wafer for a GaP light emitting diode to obtain a light emission output and the like. Carry out inspections.

Next, before the epitaxial growth is started, when the growth chamber 1a is heated together with the growth GaP solution accommodating chamber 6a, the inside of the growth chamber 1a contains P (which is more volatile than Ga contained in the GaP single crystal substrate 2). The point of maintaining the atmosphere of (phosphorus) will be described in detail.

Prior to the start of growth, the growth GaP solution 6 is kept at a constant temperature of 1000 ° C. in order to sufficiently saturate the growth GaP solution 6.
Not immersed in P solution 6. During this constant temperature holding, the growth GaP solution 6 accommodated in the growth GaP solution accommodation chamber 6a.
P (phosphorus) inside is vaporized. P (phosphorus) vaporized from the growth GaP solution 6 does not diffuse into the growth chamber 1a due to a hydrogen atmosphere gas flow.

At the same time, P (phosphorus) in the GaP single crystal substrate 2 in the growth chamber 1a is also dissociated. And the growth room 1a
The atmosphere-forming solution contained in the atmosphere-forming solution containing section 5 provided at the bottom is also sufficiently saturated during the constant temperature holding period, and P (phosphorus) evaporates. At this time, the evaporated P
Since (phosphorus) diffuses upward in the figure, the inside of the growth chamber 1a becomes an appropriate P (phosphorus) pressure atmosphere determined from the constant temperature holding temperature T _max (1000 ° C.) of the atmosphere forming solution. In this embodiment, the P (phosphorus) pressure was between 10 ^{3 and} 10 ⁴ Pa. At this time, the GaP single crystal substrate 2 may be rotated by the substrate rotation jig 4 in the direction of the arrow A shown in FIG.

As described above, a plurality of GaP single crystals set in the growth chamber 1a are kept until the growth chamber 1a reaches the initial constant temperature T _max (1000 ° C.), that is, before the start of the liquid phase epitaxial growth. The substrate 2 is kept in a P (phosphorus) gas atmosphere. Therefore, this allows GaP
Dissociation of P (phosphorus) from single crystal substrate 2 is suppressed.

However, even if the dissociation of P (phosphorus) is suppressed, a damage layer is slightly formed on the surface of the GaP single crystal substrate 2 until the temperature reaches a constant temperature. Therefore, after dipping the GaP single crystal substrate 2 in the GaP solution 6 for growth, the temperature is increased by 5 ° C. to perform meltback, and the damaged layer formed on the surface of the GaP single crystal substrate 2 is removed. I have to.

As described above, when the GaP single crystal substrate 2 is held in the growth chamber 1a, the atmosphere forming solution is stored in the atmosphere forming solution storage section 5 at the bottom of the growth chamber 1a in advance. As a result, the P (phosphorus) pressure in the growth chamber 1a is maintained at a constant value. The reason why the same solution as the growth GaP solution 6 is used as the atmosphere forming solution is that the growth Ga solution is provided in the growth chamber 1a.
This is because the properties of the growth GaP solution 6 after the introduction of the P solution 6 are not changed.

When the grooving light output of the GaP light emitting diode wafer obtained by the liquid phase epitaxial growth is compared with the case where the atmosphere forming solution is arranged and the case where the atmosphere forming solution is not arranged, the former is larger than the latter by 20%. I got At this time, no remarkable spectrum change was observed.

In this comparison, the crystal growth was performed with the same temperature program regardless of whether the solution for forming the atmosphere was provided or not. Therefore, it is considered that the difference in the grooving light output is due to the influence of the damage layer on the surface of the GaP single crystal substrate 2 generated before the growth GaP solution 6 is introduced into the growth chamber 1a. It is clear that the damage layer on the surface of the single crystal substrate 2 was suppressed.

As described above, conventionally, Ga
Until the P single crystal substrate is immersed in the growth GaP solution,
The GaP single crystal substrate is exposed in a constant temperature atmosphere of about 1000 ° C. At this time, P (phosphorus) is vaporized and damage is caused in the depth direction of the GaP single crystal substrate surface. An atmosphere forming solution is arranged in the growth chamber, and the growth chamber is maintained at an appropriate P (phosphorus) atmosphere.
Preventing dissociation of P (phosphorus) from aP single crystal substrate
The damage layer on the surface of the P single crystal substrate can be suppressed. In addition, since the amount of melt back can be reduced by suppressing the damage layer, the carrier concentration of the epitaxial growth layer can be stabilized, and the influence of impurities existing inside the GaP single crystal substrate can be suppressed. It is possible to manufacture a GaP light emitting diode with higher brightness than before.

In the above embodiment, an example of growing a GaP crystal on a GaP single crystal substrate has been described. However, if the substrate and the epitaxial layer to be grown next have the same structure, any epitaxial layer can be used. The present invention can be applied even when growing. For example, when growing a GaAs crystal on a GaAs single crystal substrate, the growth chamber is in an As atmosphere, and when growing an InP crystal on an InP single crystal substrate, the growth chamber is in a P atmosphere.
In the case of growing a GaSb crystal on an aSb single crystal substrate, the growth chambers may be maintained in an Sb atmosphere.

[0041]

According to the present invention, a damage layer on the surface of a semiconductor single crystal substrate can be suppressed. In addition, since the amount of melt back can be reduced by suppressing the damage layer, the carrier concentration of the epitaxial growth layer can be stabilized, and the influence of impurities existing inside the semiconductor single crystal substrate can be suppressed. When applied to the manufacture of light-emitting diodes, it is possible to manufacture light-emitting diodes with higher brightness than before.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing the configuration of an embodiment of a liquid phase epitaxial growth apparatus according to the present invention.

FIG. 2 is a graph showing a temperature program relating to crystal growth of the liquid phase epitaxial growth apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main body of liquid phase epitaxial growth apparatus 1a Growth chamber 2 GaP single crystal substrate 3 Substrate holding jig 4 Substrate rotation jig 5 Atmosphere forming solution storage unit 6 Growth GaP solution 6a Growth GaP solution storage unit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G077 AA03 BE43 CG01 EA01 ED06 EG07 EG20 QA02 QA38 QA71 QA72 5F053 AA01 AA02 AA03 AA21 AA22 AA23 AA25 AA26 AA48 BB01 BB02 BB12 BB52 DD01 DD02 HH04 JJ01 JJ03 KK04 KK08 LL01 LL02 PP04 RR01 RR03 RR11

Claims (6)

[Claims] In a liquid phase epitaxial growth chamber, a semiconductor single crystal substrate made of a metal (s) and an element more volatile than the metal (s) is aerated in a gas atmosphere composed of the volatile element. After that, forming an epitaxial layer on a semiconductor single crystal substrate by contacting with a solution for growing a semiconductor comprising the metal (s) and the volatile element and cooling from a predetermined temperature. Characteristic liquid phase epitaxial growth method. 2. Aeration in a gaseous atmosphere comprising a volatile element, the same solution as the semiconductor growth solution is arranged below the semiconductor single crystal substrate to heat the liquid phase epitaxial growth chamber to a predetermined temperature. The liquid phase epitaxial growth method according to claim 1, wherein the method is performed. 3. The semiconductor single crystal substrate comprises a GaP single crystal substrate, the semiconductor growth solution comprises a GaP solution in which GaP is dissolved in a Ga melt, and the volatile element is P ( 2. The liquid phase epitaxial growth method according to claim 1, comprising phosphorus. 4. The semiconductor single crystal substrate is brought into contact with the semiconductor growth solution by introducing the semiconductor growth solution into a liquid phase epitaxial growth chamber holding the semiconductor single crystal substrate. 2. The liquid phase epitaxial growth method according to 1. 5. The liquid phase epitaxial growth method according to claim 1, wherein the predetermined temperature is about 1000 ° C. 6. A substrate holding means for holding a semiconductor single crystal substrate comprising a metal (s) and an element more volatile than the metal (s), and a semiconductor comprising the metal and the volatile element A growth solution accommodating section for accommodating a growth solution for the semiconductor, a heating means, a contact means for bringing the semiconductor single crystal substrate into contact with the semiconductor growth solution, a cooling means, and a semiconductor growth means provided below the substrate holding means. Liquid phase epitaxial growth apparatus comprising: a solution accommodating section accommodating the same solution as a solution for use.