JPH11130587A - Production of nitride semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a step for subsequently forming electrodes by supplying the shortage of nitrogen in the interior of a nitride semiconductor and removing a part of a formed thin film by etching in the case of a light emitting diode(LED) or the like. SOLUTION: A substrate 3 and a raw material target 6 containing a nitride of a group III element are oppositely held in a vacuum chamber 2 and the raw material target 6 is then irradiated with a laser beam 8 to liberate the group III element and nitrogen from the raw material target 6 and deposit a nitride semiconductor of the group III element on the substrate 3. At this time, activated nitrogen is fed from the exterior into the interior of the chamber 2. In the case of an LED or the like, a nitrogen ion is previously injected into one surface of a metallic substrate composed of the group III element and the resultant metallic substrate into which the nitrogen ion is injected is used as the substrate 3 to grow a nitride semiconductor of the group III element on the ion injected surface. An inexpensive and readily available aluminum substrate is preferably used as the metallic substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for depositing a single crystal thin film of a nitride semiconductor of a group III element (indium, gallium, aluminum, etc.) on a growth substrate.

[0002]

2. Description of the Related Art As a conventional technique of this kind, a manufacturing method considered at a stage before obtaining the present invention will be described with reference to FIG. In the figure, 1 is a film forming apparatus, 2 is a vacuum chamber, 3 is a growth substrate, and a single crystal insulating substrate such as sapphire is used. Reference numeral 4 denotes a substrate holder having a built-in heater 4a,
It is rotatable. Reference numeral 5 denotes a target holder, which is of a rotary type in order to avoid a rise in the temperature of the target and a decrease in the film forming rate during the crystal production. 6 is a raw material target,
It is obtained by hardening a polycrystalline powder of a nitride semiconductor of a group III element by a press machine. When depositing a mixed crystal of nitride on the growth substrate 3, polycrystalline powder of each element is mixed so as to have a desired composition ratio. An exhaust device 7 is connected to the exhaust port 2a of the chamber. Reference numeral 8 denotes a laser beam, which is condensed by a condenser lens 9 and radiated onto the raw material target 6 from a window 2b of the chamber.

Next, the manufacturing method will be described in the order of steps. The growth substrate 3 made of sapphire is mounted on the substrate holder 4 and the raw material target 6 is mounted on the target holder 5. While the inside of the chamber 2 is depressurized, the growth substrate 3 is heated and cleaned by the heater 4a, and then cooled to a film forming temperature.

While rotating a raw material target 6 (made of, for example, InN), the surface thereof is scanned with a laser beam 8 to give energy to release group III elements and nitrogen atoms, ions, and molecules from the target, thereby obtaining III. A nitride semiconductor of a group III element is deposited on the growth substrate 3. When a multilayer film such as a p-type semiconductor film and an n-type semiconductor film is formed on the substrate 3 as in the LED shown in FIG. 6, raw material targets corresponding to each layer are attached to the target holder 5 in advance, and Are sequentially deposited on the growth substrate in the same manner as described above.

[0005]

In the conventional production method, for example, InN
A part of the group III element and nitrogen released like In + N are combined like In + N → InN; N + N → N ₂ , and nitrogen ions are often deficient in many cases. There is a problem that the nitrogen atoms in the thin film become insufficient and the conductivity is reduced.

When manufacturing an LED or the like, as shown in FIG. 6, an insulating substrate is used as a growth substrate and an n-type
After forming an nN film 201 and forming a p-type InN film 202 thereon, a part of the upper p-type InN film is removed by etching, and the surface of the n-type InN film 201 after the removal is removed. And the electrode 22 was formed on the p-type InN film 202. In particular, the step of etching and removing a part of the p-type InN film 202 and forming the electrode 21 on the surface after the removal has a large number of work steps, which causes a decrease in productivity.

[0007]

[Means for Solving the Problems]

(1) The invention according to claim 1 includes a substrate in a vacuum chamber;
A raw material target containing a nitride of a group I element is held oppositely, and energy is applied to the nitride of the raw material target to release the group III element and nitrogen from the raw material target, and to face the opposite surface of the substrate. The present invention relates to a method for manufacturing a nitride semiconductor, in which a nitride semiconductor of a group III element is deposited. In particular, when depositing the nitride semiconductor on the substrate, activated nitrogen is supplied into the chamber from the outside.

(2) In the invention of claim 2, in the above (1), a group III element and nitrogen are liberated from the material target by irradiating the material target with laser light. (3) In the invention of claim 3, in the above (1), III
Nitrogen ions are implanted in advance on one surface of a metal substrate made of a group III element, and the implanted metal substrate is used as the substrate, and a group III element nitride semiconductor is grown on the ion implanted surface.

(4) In the invention of claim 4, in (3), an aluminum substrate is used as the metal substrate.

[0010]

FIG. 1 shows an embodiment of the present invention, and FIG.
The same reference numerals are given to portions corresponding to and the description thereof will not be repeated. In this invention, in order to solve the problem of lack of nitrogen atoms contained in a formed nitride semiconductor single crystal thin film described in the prior art, when depositing a nitride semiconductor, activated nitrogen is introduced into the chamber from the outside. To supply. That is, in FIG. 1, the quartz tube 12 is penetrated and held on the side wall of the chamber 2, the nitrogen cylinder 13 is connected to one end of the quartz tube 12, and the other end is extended near the surface of the growth substrate 3 where the semiconductor thin film is to be formed. Let it. Ring-shaped electrodes 11a and 11b are attached to the outer periphery of a quartz tube 12 outside the chamber so as to face each other, and a high-frequency power source 14 is connected between the electrodes.

Next, the manufacturing method of the present invention will be described in the order of steps. The substrate 3 is mounted on the substrate holder 4 and the raw material target 6 is mounted on the target holder 5. While the inside of the chamber 2 is decompressed, the substrate 3 is heated and cleaned by the heater 4a, and then the temperature is lowered to the film forming temperature.

Nitrogen gas is introduced into the chamber 2 from the nitrogen cylinder 13 through the quartz tube 12 to maintain an appropriate pressure. A high frequency voltage is applied between the electrodes 11a and 11b, and the nitrogen in the tube is turned into a plasma state (called activation).
Introduce within. At the same time, the raw material target 6 is irradiated with the laser beam 8 to release the group III element and nitrogen atoms, molecules and ions from the raw material target 6. The released nitrogen ions and the activated nitrogen gas introduced from the outside react with the released atoms, molecules and ions of the group III element, and a nitride semiconductor of the group III element is deposited on the growth substrate 3.

A thin film 201 as shown in FIG.
In the case of forming a multi-layered film composed of the raw material targets 6-1 to 6-6 corresponding to the thin films 201 to 206, respectively, as shown in FIG. 6-1 is irradiated with a laser beam to form a thin film 201 to a predetermined thickness, and then the target holder 5 is rotated to the next position to irradiate the laser beam onto the raw material target 602, and the thin film 202 is similarly irradiated. Is deposited. Hereinafter, thin films 201 to 206 are sequentially deposited in the same manner.

In the example of FIG. 3, the raw material targets 6-1 to 6
Reference numeral -6 indicates that the target holder 5 can be rotated independently of the rotation of the target holder 5, so that the target material is uniformly released from the laser beam irradiation surface of the raw material target.
In the conventional LED manufacturing process, a step of etching and removing a part of the deposited thin film and thereafter forming an electrode is required, and in order to solve the problem that the number of work steps is increased and the productivity is reduced, In the present invention, a metal substrate of the same element as the nitride of the group III element deposited first on the substrate 3 is used, and nitrogen ions are implanted into one surface of the substrate 3 in advance by an ion implanter. And a nitride semiconductor n-type InN
201 and p-type InN 202 are sequentially grown.

In this case, since the substrate 3 is made of metal, it can be used instead of the conventional electrode 21. Therefore, the step of etching and removing a part of the p-type InN thin film 202, which is conventionally required, and then forming the electrode 21 is not required, and the productivity can be greatly improved. Although one laser beam is used in the example of FIG. 1, a plurality of laser beams may be used in some cases. The manufacturing method of the present invention
In the case of application to a device such as an ED, it is desirable to use an inexpensive and easily available aluminum substrate as the group III element substrate 3 '.

The desirable manufacturing conditions obtained by experiments are as follows.

[0017]

According to the present invention, activated nitrogen is supplied from the outside at the time of film formation, so that the shortage of nitrogen in the thin film, which has been a problem in the past, is replenished, and the conductivity can be improved. In the manufacture of LEDs, a metal substrate of a group III element having nitrogen ions implanted on the surface to be deposited was adopted as a growth substrate. Therefore, a part of the p-type InN film, which was conventionally required, was removed by etching, and thereafter, The step of forming an electrode is not required, thereby reducing the number of manufacturing steps and greatly improving productivity.

In the manufacturing method of the present invention, the film forming temperature is 400 to
A relatively low temperature of 800 ° C. is required, and when a multilayer film as shown in FIG. 4 is formed, diffusion of constituent molecules occurring at the boundary between the films is extremely small. Therefore, a device such as an LED having a pn junction surface. It becomes easy.

[Brief description of the drawings]

FIG. 1 is a principle configuration diagram of a film forming apparatus showing an embodiment of the present invention.

FIG. 2 is a principle sectional view for explaining a method of manufacturing a metal substrate used for the substrate 3 of FIG.

FIG. 3 is a perspective view showing a state where a plurality of types of raw material targets are mounted on a target holder 5 when a multilayer film is formed on the substrate 3 of FIG.

FIG. 4 is a sectional view of a multilayer film formed on the substrate of FIG. 1;

FIG. 5 is a diagram showing the basic configuration of a film forming apparatus conceived before obtaining the present invention.

FIG. 6 is a cross-sectional view showing a basic configuration of a conventional LED.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C30B 29/38 C30B 29/38 Z H01L 21/203 H01L 21/203 M

Claims (4)

[Claims] A substrate and a raw material target containing a nitride of a group III element are held in a vacuum chamber so as to face each other, and energy is applied to the nitride of the raw material target to produce the nitride.
In a nitride semiconductor manufacturing method in which a group III element and nitrogen are released from a raw material target and a group III element nitride semiconductor is deposited on an opposite surface of the substrate, when the nitride semiconductor is deposited on the substrate, A method for manufacturing a nitride semiconductor, wherein activated nitrogen is supplied into the chamber from outside. 2. The method for manufacturing a nitride semiconductor according to claim 1, wherein the group III element and nitrogen are released from the material target by irradiating the material target with laser light. 3. The method according to claim 1, wherein nitrogen ions are implanted into one surface of a metal substrate made of a group III element in advance, and the implanted metal substrate is used as the substrate, and nitriding of the group III element is performed on the ion-implanted surface. A method for producing a nitride semiconductor, comprising: growing a nitride semiconductor. 4. The method according to claim 3, wherein an aluminum substrate is used as the metal substrate.