WO2003065429A1

WO2003065429A1 - GaN COMPOUND SEMICONDUCTOR CRYSTAL MAKING METHOD

Info

Publication number: WO2003065429A1
Application number: PCT/JP2002/011772
Authority: WO
Inventors: Shinichi Sasaki; Masashi Nakamura; Kenji Sato
Original assignee: Nikko Materials Co., Ltd.
Priority date: 2002-01-28
Filing date: 2002-11-12
Publication date: 2003-08-07
Also published as: JP2003218043A

Abstract

A method for growing a GaN compound semiconductor crystal on the surface of a substrate which is a rare-earth group XIII (IIIB) perovskite crystal containing one or more rare earth elements, wherein the thickness of the substrate is 250 µm or less and the stress exerted by the substrate on the GaN thick-film crystal is decreased by the difference in the coefficient of thermal expansion.

Description

Specification

Manufacturing method of G a N-based compound semiconductor crystal

The present invention relates to a method for manufacturing a GaN-based compound semiconductor crystal used for manufacturing a semiconductor device, and relates to a technique for effectively preventing a crack from being generated in a growth step of a GaN-based compound semiconductor crystal. Background art

G aN-based compound semiconductors such as G aN, In G a N, A 1 G a N, and In G a A 1 N (In _x G a _y A 1 _χ _ _χ _ _γ Ν where 0≤ x, y; x + y ≤ l) is expected as a material for semiconductor devices such as light emitting devices and power devices, and is attracting attention as a material that can be applied in various other fields.

Conventionally, it has been difficult to grow a balun crystal of a GaN-based compound semiconductor. Was used.

However, since the lattice mismatch between the sapphire crystal and the GaN-based compound semiconductor crystal is large, the dislocation density of the GaN-based compound semiconductor crystal grown on the sapphire crystal increases and crystal defects occur. There was a problem. Furthermore, sapphire has low thermal conductivity and is difficult to radiate heat. there were.

Therefore, the need for a substrate having high thermal conductivity and lattice matching with the GaN-based compound semiconductor crystal has further increased, and ELO (Epitaxial lateral overgrowth) using hydride vapor phase epitaxy (hereinafter abbreviated as HVPE). Research was rapidly advanced. Here, the ELO method means that, for example, an insulating film serving as a mask is formed on a sapphire substrate, an opening is provided in a part of the insulating film, the insulating film is used as a mask, and the exposed sapphire substrate surface is epitaxy. G a N-based compound semiconductor crystal with high crystallinity as a seed for growth Is a way to grow. According to this method, the growth of the GaN-based compound semiconductor crystal starts from the surface of the sapphire substrate inside the opening provided in the mask, and the growth layer spreads on the mask, so that the dislocation density in the crystal is kept low. As a result, a GaN-based compound semiconductor crystal with few crystal defects can be obtained.

However, because the GaN-based compound semiconductor crystal obtained by the ELO method has a large thermal strain, it is necessary to remove the sapphire substrate by polishing in the wafer manufacturing process to obtain a single GaN-based compound semiconductor crystal wafer. However, there has been a problem that the GaN-based compound semiconductor crystal wafer is distorted.

Therefore, the present inventors used a rare earth 13 (3B) group perovskite crystal as one of the heterocrystalline substrate materials, and used the {011} plane or the {101} plane as a growth plane. A method for growing a GaN-based compound semiconductor by heteroepitaxy has been proposed (WO95 / 27815). Here, the {0 1 1} plane or {10 1} plane indicates a set of planes equivalent to the (0 1 1) plane and the (1 0 1) plane, respectively.

According to growth technique of the prior application, for example, a N d G a 0 _3, which is one of the rare earth 1 3 (3 B) Group Bae Robusukai DOO as the substrate, the {0 1 1} plane or the {1 0 1} When GaN is grown on the surface, lattice mismatch can be reduced to about 1.2%. This lattice mismatch value is extremely small compared to the lattice mismatch value when sapphire or a SiC used as a substitute is used as a substrate. Therefore, since the dislocation density in the crystal is reduced, a GaN-based compound semiconductor crystal with few crystal defects can be grown.

However, when grown to G a N sintered AkiraAtsumaku the N d G a 0 ₃ substrate by using the growth method of the prior application, the temperature lowering process after growing the G a N crystal, Nd G a 0 ₃ substrate and G a N by the difference in thermal expansion coefficient between crystal thick film cracking in G a N crystal is a problem that there is arising a possibility it found that the alien.

An object of the present invention is to provide a method for growing a GaN-based compound semiconductor crystal, which can effectively prevent a GaN crystal thick film from being cracked in a GaN-based compound semiconductor crystal growth step. With the goal. Disclosure of the invention In order to achieve the above object, the present invention provides a GaN-based compound semiconductor crystal on the surface of a rare earth 13 (3B) group perovskite crystal containing one or more rare earth elements as a substrate. In the growing method, the thickness of the substrate is 25 μμτα or less. In other words, by reducing the thickness of the substrate, the amount of expansion on the substrate side during the temperature drop process after the growth of a thick film of a GaN-based compound semiconductor crystal is reduced, and the difference in the coefficient of thermal expansion causes the GaN-based compound to grow. The stress applied to the compound semiconductor crystal from the substrate was reduced. This makes it possible to efficiently manufacture high-quality GaN-based compound semiconductor crystals without cracks. .

For example, a N d G a 0 ₃ as the substrate, when growing the G a N crystal on the surface, when the thickness is used the following NGO substrate 250 m is, G a N crystal thick film cracking Ji live Probability can be less than 50%.

Also, since the amount of expansion can be reduced as the thickness of the substrate is reduced, it is more effective to reduce the thickness of the substrate to prevent the GaN crystal thick film from cracking due to stress. For example, by using a substrate having a thickness of 120 μιη, the probability that cracks occur in the Ga a thick film can be reduced to almost 0%. However, the thickness of the substrate is desirably 100 / m or more, more desirably 120 μπι or more, from the viewpoint of ease of handling of the substrate. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a preferred embodiment of the present invention, the case of growing a G a New reduction compound semiconductor crystals N d G a 0 ₃ crystal as a substrate.

First, a substrate for crystal growth by slicing an ingot of N d G a 0 _3. At this time, N d G a 0 ₃ size of the substrate is 2 inches in diameter, and a thickness of 1 20 μηι. Next, the 5 minutes ultrasonic cleaning N d G a 0 ₃ substrate was mirror-polished in Aseton was performed for 5 minutes ultrasonic cleaning in methanol followed. Thereafter, the droplets were blown off by blowing with N ₂ gas and air-dried. Then, it washed N d G a 0 ₃ substrate sulfuric acid Etsuchanto (phosphoric acid: sulfuric acid = 1: 3, 80 ° C ) for 5 minutes etching at. Then, the N d G a 0 ₃ substrate was placed at a predetermined site within hydride VP E device, the substrate temperature while introducing N ₂ gas was raised to 6 20 ° C, and G a metal And G a C 1 generated from HC 1 gas is supplied to the N d G a 0 ₃ on the substrate using the NH ₃ gas N ₂ carrier gas, forming a G a N protective layer of about 1 0 0 nm did. Since N d G a 0 ₃ would generate a Neojiumu compound reacts with NH ₃ or H ₂ at 8 0 0 ° C over a high temperature, the N ₂ is used as carrier gas in the present embodiment, 6 2 0 ° By forming the protective layer at a low temperature of C, neodymium compounds are prevented from being generated.

Next, the substrate temperature was raised to 100 ° C., and the G a C 1 generated from the G a metal and the HC 1 gas and the NH ₃ gas were N d G a 0 using the N ₂ carrier gas. _It was supplied on _three substrates. At this time, G a C l partial pressure ^{5. 0 X 1 0_ 3 atm,} NH 3 partial pressure 3. 0 X ¹ 0- 1 atm become as about 4 0 mu while controlling the respective gas introduction rate A GaN compound semiconductor crystal was grown at a growth rate of ΐη / h for 300 minutes.

Thereafter, the carrier gas is switched from N ₂ gas to H ₂ gas, the gas partial pressure H ₂ 9 0%, adjusted to be NH ₃ 1 0%, was 1 hour heat treatment. The N d G a O ₃ substrate having a thickness of 3 5 0 m The Netsusho management could be entirely removed by reductive decomposition.

Thereafter, cooling was performed at a cooling rate of 5.3 ° C. Z min for 90 minutes to obtain a crack-free GaN thick film crystal having a diameter of 2 inches and a film thickness of about 600 × m.

Further, 2 inch diameter, with a N d G a 0 ₃ substrate having a thickness of 1 2 0 mu m, was grown Repetition rate G a N thick crystal, the cracks in the cooling step after the crystal growth The probability of occurrence was almost 0%.

On the other hand, was a two-inch diameter which has been used in the manufacture of conventional G a N thick crystal, grown use Ite 0 & 1 ^ thick crystal thickness 3 7 0 111 (10 _& 0 ₃ substrate In this case, the probability of occurrence of cracks in the cooling process after crystal growth was about 90%.

In addition, the plane orientation of the GaN thick film crystal obtained in the present example is controlled, and further mirror-finished, for example, processed to a thickness of 350 μηη to obtain a substrate for a semiconductor element. As a result, a semiconductor device having excellent device characteristics could be manufactured.

As described above, the force S specifically describing the invention made by the inventor based on the embodiment, the present invention is not limited to the above embodiment. Rare-earth 1 3 which is used as a substrate (3 B) Group Bae Ropusukai DOO crystals is not limited to N d G a 0 ₃ crystal, for example, Nd A 10 ₃ , Nd I n〇 _{3 and the} like can be used.

Also, G a The growth conditions for N-based compound semiconductor crystal, 0 & 0 1 partial pressure ^{1. 0 X 1 0- 3 ~ 1.} 0 X 1 0- 2 atm, NH 3 partial pressure 1. 0 X ^{1 0- 1 ~ 4. 0 X 1} 0 one ¹ atm, the growth rate is 3 0~: L 0 0 m / li, growth temperature 9 3 0~: 1 0 5 0 ° C, the cooling rate is 4-10 . Desirably, CZmin.

According to the present invention, the rare earth 1 3 comprising one or two or more kinds of rare earth elements (3 B) Group Bae Ropusukai preparative crystals (e.g., NDG a 0 ₃₎ a G a N-based compound semiconductor crystal on the surface as the substrate In the growing method, the thickness of the substrate is set to 25 μμπι or less, and the stress applied to the GaN thick film crystal from the NGO substrate is reduced by the difference in coefficient of thermal expansion. It is possible to prevent the crystal from cracking and to improve the production efficiency. Industrial applicability

The present invention is not limited to the growth of GaN compound semiconductor crystals, and can be used, for example, when growing other GaN-based compound semiconductor crystals such as InGaN and A1GaN.

Claims

The scope of the claims

1. A method for growing a GaN-based compound semiconductor crystal on a surface of a rare earth 13 (3B) group perovskite crystal containing one or more rare earth elements,

A method for producing a GaN-based compound semiconductor crystal, wherein the thickness of the substrate is 250 zm or less.

2. The rare earth 1 3 (3 B) Group Bae Ropusukaito crystal substrate manufacturing method of G a N-based compound semiconductor crystal according to claim 1, characterized in that the NDGA 0 ₃ crystal.