JP2593597B2 - Liquid phase growth method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepwise reduction of a gas concentration in a flow direction of a dopant gas, that is, a uniformity of a substrate by effectively preventing a decrease in a concentration gradient and resulting from a difference in a set position of a substrate. The present invention relates to a liquid phase growth method and a liquid phase growth apparatus that eliminates non-uniformity of a dopant concentration in a liquid phase growth layer between substrates.

[0002]

2. Description of the Related Art Conventionally, for example, in order to manufacture a GaP green light emitting diode, an n-type GaP layer is formed on an n-type GaP substrate using a liquid phase growth apparatus 2 as shown in FIG. A p-type GaP layer is formed on the n-type GaP layer to form a pn junction.

The liquid phase growth apparatus 2 has a reaction tube 4 made of quartz. A growth boat 6 is arranged in the reaction tube 4. The growth boat 6 includes a substrate holder 8 for setting a plurality of, for example, five GaP substrates W1 to W5 in a longitudinal direction, and a plurality of growth solution reservoirs 10a to 10e provided corresponding to the respective substrates W1 to W5. Having and the substrate holder 8
It has a substrate holder 8 and a solution storage boat 12 slidable with respect to each other.

At a position slightly away from the growth boat 6,
A dopant evaporation source 14 made of, for example, zinc is provided. A gas supply pipe 16 for supplying gas is provided at one end of the reaction tube 4, and a gas outlet 18 for discharging gas is provided at the other end.

The heaters 20a and 20b are provided outside the reaction tube 4. 21 is a drawbar.

In order to manufacture, for example, a GaP green light-emitting diode using the above-described liquid phase growth apparatus 2, for example, zinc is added to a growth solution (Ga melt) as zinc vapor, and a gas supply pipe 16 is formed. It is necessary to perform addition of a dopant such as addition of a nitrogen atom using ammonia gas. These dopants are supplied to the plurality of growth solution reservoirs 10a to 10 while flowing in a gas state from the supply side to the discharge side.
It comes into contact with and melts the Ga melt in e.

However, when a plurality of growth solution (Ga melt) reservoirs 10a to 10e exist in the flow direction of the dopant gas as described above, the growth solution reservoir located at the most upstream position in the flow direction of the dopant gas. G of 10a
a. The dopant gas is first dissolved in the melt, and is sequentially dissolved in the next Ga melt, and the dopant gas concentration decreases by the amount of the melt to reach the next Ga melt. Is decreased, and the concentration of the dopant gas absorbed by the Ga melt in the growth solution reservoir 10e, which is the most downstream, is the lowest.

Accordingly, the amount of Zn contained in the liquid-phase growth layer grown on the substrate W1 located at the most upstream position in the flow direction of the dopant gas is the highest, and the zinc content of the liquid-phase growth layer of each substrate is high. It gradually decreases in the flow direction of the dopant gas,
The zinc content of the liquid phase growth layer of the substrate W5 located at the most downstream position is the lowest. Since the zinc content affects the luminance of the light emitting device, there has been a problem that the luminance of the obtained GaP light emitting device is not uniform depending on the installation position of the substrate.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and is intended to reduce the gas concentration in the flow direction of the dopant gas in a stepwise manner, that is, to reduce the concentration gradient. Provided is a liquid phase growth method and apparatus capable of effectively preventing and uniformizing the dopant concentration in a liquid phase growth layer between substrates due to a difference in a set position of a substrate. The purpose is to:

[0010]

In order to solve the above-mentioned problems, a liquid phase growth method of the present invention comprises a substrate holder for setting a plurality of substrates in a longitudinal direction, and a plurality of growth plates provided corresponding to each substrate. A growth boat having a solution storage part and provided on the upper surface of the substrate holder and having a solution storage boat slidable with respect to the substrate holder is disposed in a reaction tube, and a growth boat is provided in the reaction tube. The substrate holder or the solution storage boat is moved while supplying the dopant gas so as to flow from one direction to the other direction, and the substrate and the growth solution are brought into contact with each other to cause liquid phase growth on the substrate and to perform growth for a predetermined time. Then, the substrate and the growth solution are separated from each other, and the dopant gas is supplied stepwise in the direction of the dopant gas flow using a reactor for liquid phase growth in which the growth is stopped. It is obtained so as to make uniform the flow direction of the gas concentration.

Further, the liquid phase growth apparatus of the present invention has a substrate holder for setting a plurality of substrates in a longitudinal direction, a plurality of growth solution reservoirs provided corresponding to each substrate, and an upper surface of the substrate holder. A growth boat having a substrate holder and a solution storage boat slidable with respect to each other is disposed in a reaction tube, and a gas supply tube is provided in the reaction tube at one longitudinal end thereof, and A gas outlet is provided at the other end, a dopant gas is supplied so as to flow from the gas supply pipe to the gas outlet, and the substrate holder or the solution storage boat is moved to bring the substrate and the growth solution into contact with each other, and the liquid is supplied onto the substrate. phase growth, after performing the predetermined time growth, distancing the substrate and the growth solution, the liquid phase growth apparatus that stop the growth, Rukoto provided a partition on one end side of the reaction tube
Thereby , the reaction tube is separated into a gas supply portion communicating with the gas supply tube by the partition wall and a main zone in which the growth boat is arranged, and a longitudinal direction in the main zone is separated.
In addition, a plurality of gas inlets are stepwise
It is provided so as to protrude from the partition .

Removably mounted in the liquid phase growth apparatus.
By forming a partition on one end side of the reaction tube,
A gas communicating the reaction tube with a gas supply tube through the partition.
The main zone where the supply unit and the growth boat are located
Into the main zone, and a plurality of
The gas inlet of the partition wall at predetermined intervals,
A stepwise gas introduction port can be easily formed by using a gas introduction cassette configured to be provided so as to protrude from the gas introduction cassette.

[0013]

According to the present invention, since the dopant gas is supplied stepwise into the main zone of the reaction tube through the plurality of gas inlets, the plurality of growth solution reservoirs located along the flow of the dopant gas are provided. In the case where the dopant gas is dissolved in the Ga melt and the gas concentration gradient is reduced only by supplying the dopant gas from a single gas supply port as in the related art, the dopant gas concentration in the main zone is uniform. Therefore, the concentration of the dopant dissolved in the Ga melt can be maintained uniformly irrespective of the positions of the plurality of growth solution reservoirs, so that the luminance of the obtained light emitting diode is uniform without any variation.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
This will be described with reference to FIG.

In this embodiment, the same or similar members as those of the conventional device shown in FIG. 1 and 2, the liquid phase growth apparatus 2 of the present invention has a reaction tube 4 made of quartz, and a growth boat 6 is arranged in the reaction tube 4. The growth boat 6 includes a substrate holder 8 on which a plurality of, for example, five GaP substrates W1 to W5 are set in a longitudinal direction, and a plurality of growth solution (Ga melt) reservoirs provided corresponding to the respective substrates W1 to W5. A solution storage boat 1 having 10a to 10e and provided on the upper surface of the substrate holder 8 and slidable with respect to the substrate holder 8.
And 2.

At a position slightly away from the growth boat 6,
For example, a dopant evaporation source 14 made of Zn is provided. A gas supply pipe 16 for supplying gas is provided at one end of the reaction tube 4, and a gas outlet 18 for discharging gas is provided at the other end of the reaction tube 4. In addition, 2
Reference numerals 0 a and 20 b denote heaters provided outside the reaction tube 4. 21 is a drawbar.

A partition 22 is provided at one end of the reaction tube 4, and is separated by the partition 22 into a gas supply section 24 and a main zone 26 in which the growth boat 6 is arranged. The partition 22 is provided with a plurality of, three in the figure, gas introduction portions 28 projecting in the direction of the main zone 26. The leading end of the gas introduction part 28 is opened, and gas introduction ports 28a, 28b, 28c are provided in the main zone 26 stepwise, that is, at predetermined intervals in the longitudinal direction. Even if the gas supplied from 28b, 28c is dissolved in the growth solution (Ga melt), the gas concentration is maintained uniformly in the main zone 26.

Using the liquid phase growth apparatus 2 as described above, the growth boat 6 is driven by a slide boat method, and for example, an n-type GaP layer and a p-type GaP
Layers are formed to produce a GaP green light emitting diode.

For example, H ₂ gas containing ammonia (NH ₃ ) is supplied from the gas supply unit 24 to each of the inlets 28a, 28b, 2
8c through the growth solution storage portions 10a-1 of the growth boat 6
0e and dissolved in the growth solution (Ga melt). Using this growth solution, an n-type GaP layer is formed by an ordinary method.

Further, for example, zinc is evaporated by heating the dopant evaporation source 14 made of zinc, and this zinc vapor is supplied to the respective inlets 28a, 28b, 28c together with, for example, H ₂ gas.
Through the growth solution reservoirs 10a to 10e of the growth boat 6
And dissolved in the growth solution (Ga melt). Using this growth solution, a p-type GaP layer is formed by an ordinary method.

In the present invention, since a plurality of gas inlets 28a, 28b, and 28c are provided in a stepwise manner as described above, the gas supplied from the gas inlets 28a, 28b, and 28c is supplied with the growth solution (Ga). Even when the gas is dissolved in the melt, the gas concentration is maintained uniformly in the main zone 26.

For example, the most upstream gas inlet 2
Even if zinc vapor is supplied from 8a and dissolved in Ga melt such as the growth solution reservoirs 10a and 10b located on the upstream side, even if the concentration of the dopant gas supplied from the gas inlet 28a decreases, it is located next. Gas inlet 28b
Again, the zinc vapor having the initial concentration is supplied again, so that the concentration of the dopant gas dissolved in the Ga melt in the growth solution reservoirs 10b, 10c, 10d located in the middle stream does not decrease.

Similarly, even if the concentration of the dopant gas supplied from the gas inlets 28a and 28b is reduced by dissolving in the Ga melt such as the growth solution reservoirs 10a, 10b, 10c and 10d located on the upstream and middle streams, Since the initial concentration of zinc vapor is supplied again from the gas inlet 28c located downstream, the growth solution reservoir 10 located downstream is
The concentration of the dopant gas such as c, 10d, and 10e dissolved in the Ga melt does not decrease.

As described above, since the dopant gas is supplied stepwise into the main zone 26 of the reaction tube 4 through the plurality of gas inlets 28a to 28c, the growth solution reservoir located along the flow of the dopant gas is stored. G of parts 10a to 10e
a) Even if the dopant gas dissolves in the melt and the gas concentration gradient is reduced only by supplying the dopant gas from a single gas supply port as in the related art, the dopant gas concentration in the main zone 26 is uniform. Therefore, the concentration of the dopant dissolved in the Ga melt can be maintained uniformly irrespective of the position of the growth solution reservoirs 10a to 10e, so that the brightness of the obtained light emitting diode is uniform without variation.

The liquid phase growth of the n-type GaP layer can be performed in an argon atmosphere in addition to the H ₂ atmosphere. Also, p
Cd can be used as an acceptor impurity of the GaP type layer in addition to zinc.

In the example shown in FIGS. 1 and 2, the gas supply section 24 and the main zone 26 are formed by providing the partition wall 22 in the reaction tube 4. As a means for forming the gas supply unit 24 and the main zone 26, as shown in FIGS. 3 and 4, an opening 32 is provided at one end of the tubular body 30.
A partition 34 is provided at the other end, and a plurality of, three in the figure, gas introduction portions 36 are provided on the partition 34 so as to protrude outwardly.
It is also possible to form the gas introduction cassette 38 in which a, 36b, and 36c are formed as a separate body, and to insert the gas introduction cassette 38 into the gas supply side in the reaction tube 4.

Next, an example of the method of the present invention will be described. Example 1 Using the liquid phase growth apparatus of the present invention shown in FIG. 1, an experiment was performed in the following procedure.

A growth boat is placed in the reaction tube.
The temperature is raised to 1000 ° C. in an H ₂ atmosphere to dissolve the GaP polycrystal in the Ga melt into the Ga melt.

By operating the pull rod 21, the Ga melt 1
0a to 10e are brought into contact with the substrates W1 to W5. next,
The temperature is raised to 1010 ° C., and a part of the substrate is melted in Ga melt to perform melt back.

An n-layer is first grown at a rate of 1 to 3 ° C. per minute while cooling the apparatus. Subsequently, the gas supply pipe 1
The cooling is continued while supplying ammonia gas together with H ₂ gas from 6 to grow an n-layer to which nitrogen is added. At this time,
Ammonia gas is supplied to the respective growth solutions almost uniformly through the inlets 28a, 28b, 28c, so that there is no difference in the amount of nitrogen added between the substrates.

Finally, the dopant evaporation source 14 is heated and cooled while supplying zinc vapor together with H ₂ gas, thereby growing a p-type layer. At this time, the zinc vapor is
Since the growth solutions are supplied almost uniformly to the respective growth solutions via 8a, 28b, and 28c, good results are obtained in which there is no difference in zinc concentration between substrates. When you have finished growing, drawbar 2
1 is operated to separate the Ga melt from the substrate to complete the growth.

When the p-layer carrier concentration of the wafer after the reaction was measured by CV measurement, it was found that the difference between the substrates was good as shown in FIG. Also,
As shown in FIG. 6, it was found that the luminance distribution was good with a small difference between the substrates.

Comparative Example 1 Using the conventional liquid phase growth apparatus shown in FIG. 9, an experiment was performed in the following procedure. A growth boat is placed in the reaction tube. The temperature is raised to 1000 ° C. in an H ₂ atmosphere to dissolve the GaP polycrystal in the Ga melt into the Ga melt.

By operating the pull rod 21, the Ga melt 1
0a to 10e are brought into contact with the substrates W1 to W5. next,
The temperature is raised to 1010 ° C., and a part of the substrate is melted in Ga melt to perform melt back.

An n-layer is first grown at a rate of 1 to 3 ° C. per minute while cooling the apparatus. Subsequently, the gas supply pipe 1
The cooling is continued while supplying ammonia gas together with H ₂ gas from 6 to grow an n-layer to which nitrogen is added.

Finally, cooling is continued while heating the dopant evaporation source 14 and supplying zinc vapor together with H ₂ gas to grow a p-type layer. When the growth is completed, the pull rod 21 is operated to separate the Ga melt from the substrate to complete the growth.

When the p-layer carrier concentration of the wafer after the reaction was measured by CV measurement, it was found that as shown in FIG. 7, the carrier concentration gradually decreased in the flow direction of the dopant gas. Also,
As shown in FIG. 8, the luminance distribution was found to have a large difference between the substrates.

[0038]

As described above, according to the liquid phase growth method and apparatus of the present invention, the stepwise decrease of the gas concentration in the flow direction of the dopant gas, that is, the decrease of the concentration gradient is effectively prevented, and the uniformity of the gas concentration is prevented. This makes it possible to prevent the dopant concentration in the liquid phase growth layer between the substrates from becoming non-uniform due to the difference in the set position of the substrates.

[Brief description of the drawings]

FIG. 1 is a schematic side view illustrating an example of the apparatus of the present invention.

FIG. 2 is a schematic top view of FIG. 1;

FIG. 3 is a schematic side view showing an example of a case where a gas introduction cassette is attached to the apparatus shown in FIG. 1;

FIG. 4 is an explanatory diagram illustrating a gas supply cassette.

FIG. 5 is a graph showing a p-layer carrier concentration distribution in Example 1.

FIG. 6 is a graph showing a luminance distribution in the first embodiment.

FIG. 7 is a graph showing a p-layer carrier concentration distribution in Comparative Example 1.

FIG. 8 is a graph showing a luminance distribution in Comparative Example 1.

FIG. 9 is a schematic side view illustrating an example of a conventional liquid phase growth apparatus.

[Explanation of symbols]

 Reference Signs List 2 Liquid phase growth apparatus 4 Reaction tube 6 Growth boat 8 Substrate holder 10a to 10e Growth solution storage section 12 Solution storage boat 14 Dopant evaporation source 16 Gas supply pipe 18 Gas outlet 21 Pull rod 28a to 28c Gas inlet 38 Gas introduction cassette

Claims (4)

(57) [Claims] 1. A substrate holder for setting a plurality of substrates in a longitudinal direction, a plurality of growth solution reservoirs provided corresponding to each substrate, and provided on an upper surface of the substrate holder and mutually separated from the substrate holder. A growth boat having a solution reservoir boat that is slidable is arranged in the reaction tube,
While supplying the dopant gas so as to flow in one direction from the longitudinal direction to the other direction in the reaction tube, the substrate holder or the solution storage boat is moved to bring the substrate and the growth solution into contact with each other to cause liquid phase growth on the substrate, After performing growth for a predetermined time, the substrate and the growth solution are separated from each other, and a dopant gas is supplied in a stepwise manner in the flow direction of the dopant gas using a liquid-phase growth reactor configured to stop the growth. Liquid phase growth method, wherein the dopant gas concentration is made uniform in the flow direction. 2. A substrate holder for setting a plurality of substrates in a longitudinal direction, a plurality of growth solution reservoirs provided corresponding to each substrate, and provided on an upper surface of the substrate holder. A growth boat having a solution reservoir boat that is slidable is arranged in the reaction tube,
In the reaction tube, a gas supply pipe is provided at one end in the longitudinal direction, and a gas outlet is provided at the other end, a dopant gas is supplied so as to flow from the gas supply pipe to the gas outlet, and a substrate holder or a solution reservoir is provided. A liquid phase growth apparatus in which a boat is moved to bring a substrate and a growth solution into contact with each other to perform liquid phase growth on the substrate, and after performing growth for a predetermined time, the substrate and the growth solution are separated from each other and growth is stopped. in, the Rukoto provided a partition on one end side of the reaction tube, the reaction tube was separated into a main zone a gas supply unit which communicates with the gas supply pipe and the growth boat is located by the partition wall , 該Me
Step multiple gas inlets in the longitudinal direction in the in-zone
The liquid phase growth apparatus, wherein the apparatus is provided so as to protrude from the partition wall at a predetermined interval . 3. A substrate on which a plurality of substrates are set in a longitudinal direction.
Holder and multiple growth solutions provided for each substrate
When it has a reservoir and is provided on the upper surface of the substrate holder,
A solution reservoir that is slidable with the substrate holder.
A growth boat having a
A gas supply pipe is provided inside the reaction tube at one end in the longitudinal direction.
Gas outlet at the other end, and
Outlet Supply the dopant gas so that it flows to the substrate
Move the holder or the solution storage boat to
To grow in liquid phase on the substrate and grow for a predetermined time.
After that, the substrate is separated from the growth solution to stop the growth.
Of gas used in a liquid phase growth apparatus
This is a cassette that can be detachably mounted in the liquid phase growth apparatus.
To form a partition wall at one end of the reaction tube.
The reaction tube is connected to the gas supply tube by the partition.
The main where the gas supply section and the growth boat are located
Zone in the main zone.
Several gas inlets are stepwisely inserted at predetermined intervals.
A gas inlet cassette that is configured to protrude from the wall
To 4. A growth solution is brought into contact with a plurality of substrates set in a longitudinal direction of the reaction tube while supplying a dopant gas from a gas supply tube provided at one end of the reaction tube, and a liquid is supplied onto the substrate. A gas introduction cassette used in a liquid phase growth apparatus adapted to perform phase growth, wherein the gas introduction cassette is detachably mounted in the liquid phase growth apparatus to form a partition wall at one end of the reaction tube, thereby forming the reaction tube. The pipe is separated into a gas supply part communicating with the gas supply pipe by the partition and a main zone in which a growth boat is arranged, and a plurality of gas inlets are provided stepwise in the longitudinal direction in the main zone. A gas introduction cassette configured to protrude from the partition at a predetermined interval.