JP3122644B2 - Method for manufacturing semiconductor light emitting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of manufacturing a high-brightness, high-definition semiconductor light emitting device.

[0002]

2. Description of the Related Art Light emitting diodes (LEDs) are easy to see even in bright places and are widely used in display devices such as various display lamps. For the green and yellow-green LEDs, an element using GaP doped with N in the light-emitting portion, a yellow L
As the ED, there is an element using GaAsP doped with N in the light-emitting part, and as the red LED, an element using GaAsP or AlGaAs doped with Zn-O in the light-emitting part.

[0003] However, the above LED has the following disadvantages. That is, GaP and GaAsP are indirect transition type semiconductors, and the impurity is added to form the light emission center, so that the concentration of the light emission center becomes low. Therefore, when the current is increased, the light emission output is immediately saturated, and high luminance cannot be obtained. Also, Al _x Ga _1-x As (0 ≦ x ≦
1) is used as a high-brightness LED such as a stop lamp, but when the Al composition ratio x exceeds 0.45, an indirect transition occurs. Therefore, the efficiency decreases as the Al composition ratio increases, that is, as the emission wavelength decreases.
Further, blue light emission cannot be obtained with GaP, GaAsP, and AlGaAs-based semiconductors.

[0004] InGaN-based materials have been studied as semiconductor materials which are of direct transition type in the entire wavelength region. I
In nGaN, red to ultraviolet light emission can be obtained by changing the group III composition as shown in FIG. In particular, research on devices using a sapphire substrate and GaN has been advanced. For example, Appl.Phys.Lett.48 (1986) p.3
As shown in FIG. 53, A between the sapphire substrate and GaN
By introducing a buffer layer made of 1N, a good GaN crystal can be obtained. Also, Jpn.J.Appl.Phys.30 (1
991) As shown in L1705, sapphire substrate and GaN
By introducing a buffer layer made of GaN grown at a low temperature between these steps, a good GaN crystal can be obtained. further,
As shown in Jpn. J. Appl. Phys. 28 (1989) L2112, M
By irradiating g-doped GaN with an electron beam, p-type G
aN was obtained, and a high-luminance blue LED was obtained.

[0005]

However, in order to realize a light emitting device using InGaN of the direct transition type as described above, it is necessary to continuously grow a plurality of compound semiconductor layers. When a plurality of semiconductor layers having different compositions of group III are continuously grown, the generated lattice strain induces lattice defects, and luminous efficiency is reduced due to pits (holes) and cracks (cracks). In particular, in the case of a nitride-based compound semiconductor layer, since the bonding force between atoms is strong, there is a problem that the number of lattice defects due to lattice distortion increases as the layers are stacked.

An object of the present invention is to solve the above-mentioned problems, and to provide a method for manufacturing a high-brightness, high-definition semiconductor light emitting device by relaxing and stacking lattice strains when compound semiconductor layers are continuously grown. The purpose is to provide.

[0007]

A method for manufacturing a semiconductor light emitting device according to the present invention is a method for manufacturing a semiconductor light emitting device in which a semiconductor layer made of an InGaN-based material is laminated on a substrate, comprising the steps of: In _x Ga _{1 -x} On a first semiconductor layer made of N (0 ≦ x ≦ 1), a second semiconductor made of AlN or In _y Ga _1-y N (0 ≦ y ≦ 1) grown at a lower temperature than the first semiconductor layer. Forming a semiconductor layer, and forming an In _z Ga _1-z on the second semiconductor layer at a higher temperature than the second semiconductor layer;
A third semiconductor layer made of N (0 ≦ z ≦ 1) is formed.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 3 is a sectional view showing a semiconductor light emitting device according to Embodiment 1 of the present invention. This semiconductor element
On a (0001) plane of a sapphire substrate 1, a buffer layer 2 made of AlN or GaN, Si-doped n-In _x G
a _1-x N layer 3, Mg-doped high resistance In _x Ga _1-x N layer 4,
Buffer layer 2 made of AlN or GaN, Si-doped _{n-In x Ga 1-x} N layer 5, Mg-doped high resistance an In _x Ga
_{A 1-x} N layer 6, a buffer layer 2 made of AlN or GaN, a Si-doped n-In _x Ga _1-x N layer 7, and a Mg-doped high-resistance In _x Ga _1-x N layer 8 are laminated. Buffer layer 2 made of the AlN or GaN, Si-doped _{n-In x Ga 1-x} N layer 5, Mg-doped high resistance an In _x Ga
_{The 1-x} N layer 6, the buffer layer 2 made of AlN or GaN, the Si-doped n-InN layer 7, and the Mg-doped high-resistance InN layer 8 are composed of the Mg-doped high-resistance In _x Ga _1-x N layer 4 and the Mg-doped high _- resistance layer. The resistance In _x Ga ₁ -xN layer 6 is partially removed so as to be exposed. Mg-doped high resistance In _x
Part of the Ga _1-x N layer 8, Mg-doped high resistance In _x Ga _1-x
The exposed portions of the N layer 4 and the Mg-doped high resistance In _x Ga ₁ -xN layer 6 are formed as p-type regions 4a, 6a, 8a,
The p-type Al electrode 1 is formed on the p-type regions 4a, 6a, and 8a.
0, 11, and 12 are provided, and an n-type Al electrode 9 is provided on the side surface on which the semiconductor is not exposed.

A semiconductor device according to a first embodiment will be described with reference to FIGS. First, as shown in FIG. 1, the sapphire substrate 1 was thermally cleaned at a substrate temperature of 1150 ° C. Thereafter, the substrate temperature is lowered to 600 ° C., and a buffer layer 2 made of AlN or GaN is grown on the (0001) plane of the sapphire substrate 1.
° C, the Si-doped n-In _x Ga _1-x N layer 3 and M
A g-doped high resistance In _x Ga _1-x N layer 4 was grown. Next, the substrate temperature is lowered to 600 ° C., and a buffer layer 2 made of AlN or GaN is grown.
The temperature was raised to 00 ° C., and a Si-doped n-In _x Ga _1-x N layer 5 and a Mg-doped high-resistance In _x Ga _1-x N layer 6 were grown.
Further, the substrate temperature is lowered to 600 ° C., and AlN or Ga
A buffer layer 2 made of N is grown. Subsequently, the substrate temperature is raised to 800 ° C., and the Si-doped n-In _x Ga _{1 -x} N layer 7 is formed.
And a Mg-doped high resistance In _x Ga ₁ -xN layer 8 was grown.

As a method for growing each of the semiconductor layers, MO
CVD method (organic metal compound vapor phase epitaxy), gas source M
The BE method (molecular beam epitaxy method) is preferred. The following compounds can be used as a source and a dopant material of the atoms forming each semiconductor layer.

Ga source: trimethylgallium (TM
G) or triethylgallium (TEG), etc. Al source: trimethylaluminum (TMA) or triethylaluminum (TEA), etc. In source: trimethylindium (TMI) or triethylindium (TEI), N source: ammonia (NH ₃ ) And other dopant materials: silane (SiH ₄ ) (for n-type dopant) and biscyclopentadienyl magnesium (Cp ₂ Mg) (for p-type dopant).

Next, as shown in FIG. 2, by dry etching or selective etching, a buffer layer 2 made of AlN or GaN, a Si-doped n-In _x Ga ₁ -xN layer 5, a Mg-doped high resistance In _x Ga _{1 -x} N layer 6, buffer layer 2 made of AlN or GaN, Si-doped n-In _x
Ga _1-x N layer 7 and Mg-doped high resistance In _x Ga _1-x N
Layer 8 is composed of Mg-doped high resistance In _x Ga _{1 -x} N layer 4 and M
The g-doped high resistance In _x Ga ₁ -xN layer 6 was partially removed so as to be exposed.

Further, Mg-doped high resistance In _x Ga ₁ -xN
In a part of the layer 8, the exposed portions of the Mg-doped high-resistance In _x Ga _1-x N layer 4 and the Mg-doped high-resistance In _x Ga _1-x N layer 6,
An electron beam was irradiated so that the electron reached a depth of about 0.5 μm to form p-type regions 4a, 6a, and 8a.

Subsequently, as shown in FIG.
a, 6a, 8a, 500 μmφ p-type Al electrode 1
An n-type Al electrode 9 is deposited on 0, 11, and 12 and on the side surface on which the semiconductor layer is not exposed. After each Al electrode was formed, the chip was divided into chips by dicing to obtain semiconductor light emitting devices.

In order to realize a multi-wavelength light emitting device using the direct transition type InGaN as described above, it is necessary to continuously grow semiconductor layers having different Group III compositions. However, as shown in FIG. 7, since there is a difference in the lattice constant, lattice distortion occurs when the crystal is continuously grown. Lattice distortion induces lattice defects, and pits (holes) and cracks (cracks) lower luminous efficiency. Therefore, the semiconductor device of the present invention has a buffer layer made of AlN or GaN interposed between the semiconductor layers. The buffer layer can reduce the lattice strain.

When each semiconductor layer is continuously grown,
An element structure for separating and controlling light emission of each layer is required. Therefore, in the method for manufacturing a semiconductor light emitting device of the present invention,
An etching step of exposing a lower semiconductor layer by removing a part of the upper semiconductor layer; and irradiating the exposed part with charged particles. For this reason, the light emitting portions of the respective semiconductor layers are formed separately and independently, so that the light emission can be separated and controlled.

Details of each semiconductor buffer layer are as follows.

AlN buffer layer 2: 500 Å thick Si-doped n-In _x Ga _1-x N layer 3: In _0.3 Ga
_0.7 N, thickness 2 μm Mg-doped high resistance In _x Ga ₁ -xN layer 4: In _0.3 Ga _0.7
N, 0.5 μm thick Si-doped n-In _x Ga _1-x N layer 5: In _0.7 Ga
_0.3 N, 1 μm thick Mg-doped high resistance In _x Ga ₁ -xN layer 6: In _0.7 Ga _0.3
N, thickness 0.5 μm Si-doped n-In _x Ga ₁ -xN layer 7: InN, thickness 1 μ
mm Mg-doped high-resistance In _x Ga ₁ -xN layer 8: InN, 0.5 μm thickness In each semiconductor layer, lattice defects such as pits and cracks were not observed.

In the semiconductor light emitting device of this embodiment,
High-efficiency, high-luminance light emission of red, green, and blue was obtained.

(Embodiment 2) FIG. 4A is a sectional view showing a state before an exposed portion of a semiconductor light emitting device according to Embodiment 2 of the present invention is formed, and FIG. FIG. 4 is a cross-sectional view showing a buffer layer of FIG.

The buffer layer 4 of the semiconductor light emitting device of the second embodiment
0a, 40b and 40c are 20 angstrom Al
N layer 41 and 20 angstroms of In _y Ga _1-y N (0
.Ltoreq.y.ltoreq.1) A multilayer body in which layers 42 are alternately laminated.

In this embodiment, the value of y is
The value is 0.3 for 0a, 0.7 for the buffer layer 40b, and 1.0 for the buffer layer 40c.

In this semiconductor light emitting device, an AlN buffer layer 41 and In _y Ga _1-y N (0 ≦ y ≦
1) Except for alternately laminating the buffer layers 42, the structure was the same as that of Example 1 and was formed by the same growth method.

In each semiconductor layer, no lattice defects such as pits and cracks were observed.

Since this buffer layer has a superlattice structure, the effect of alleviating lattice distortion is higher than that of the buffer layer of the first embodiment, and impurities that are not removed by thermal cleaning or the like remain on the substrate. Even so, since the impurities are trapped in the superlattice, the adverse effects can be eliminated.

In the semiconductor light emitting device of this embodiment,
High-efficiency, high-luminance light emission of red, green, and blue was obtained.

(Embodiment 3) FIG. 5A is a cross-sectional view showing a state before an exposed portion of a semiconductor light emitting device according to Embodiment 3 of the present invention is formed, and FIG. FIG. 4 is a cross-sectional view showing a buffer layer of FIG.

The buffer layer 5 of the semiconductor light emitting device of the third embodiment
0a, 50b and 50c are buffer layers 40a and 40b of the semiconductor light emitting device of Example 2 except that the thickness of the InGaN layer is changed.
It has the same configuration as 40b and 40c. Specifically, it has the following configuration. In _y on AlN layer 51
The Ga _1-y N (0 ≦ y ≦ 1) layer 52 is 20 angstroms, and the In _y Ga _1-y N layer on the AlN layer 51 thereon is formed.
(0 ≦ y ≦ 1) layer 53 is 30 angstroms,
In _y Ga _1-y N (0 ≦ y ≦
1) Layer 54 is 40 Å and A
In _y Ga _1-y N (0 ≦ y ≦ 1) layer 55 on the 1N layer 51
Is 90 Å, and the AlN layer 51 thereon is
The In _y Ga _1-y N (0 ≦ y ≦ 1) layer 56 above the AlN layer 51 and the In _y G
a _1-y N layers (0 ≦ y ≦ 1).

In this semiconductor light emitting device, an AlN layer 51 and an In _y Ga _{1 -y} N (0 ≦ y ≦ 1) layer 5 are used as buffer layers.
55, 56 were alternately laminated, and the same as in Example 1 was prepared.

In each semiconductor layer, no lattice defects such as pits and cracks were observed. Since this buffer layer has a superlattice structure similarly to the second embodiment, the buffer layer of the first embodiment is more effective in reducing lattice distortion. In the semiconductor light emitting device of this example, high-efficiency, high-luminance light emission of red, green, and blue was obtained.

(Embodiment 4) FIG. 6 (a) is a sectional view showing a state before an exposed portion of a semiconductor light emitting device according to a fourth embodiment of the present invention is formed, and FIG. FIG. 4 is a cross-sectional view showing a buffer layer of FIG.

The buffer layer 6 of the semiconductor light emitting device of the fourth embodiment
0a, 60b, and 60c are a layer 61 and an AlN layer 62 made of AlN or GaN, and In _y Ga _1-y N (0 ≦ y ≦
1) The layer 63 is laminated. In this embodiment, the value of y is 0.3 in the buffer layer 40a, 0.7 in the buffer layer 40b, and 1.0 in the buffer layer 40c.

In this semiconductor light emitting device, an AlN layer 61, an AlN layer 62 and In _y Ga _1-y are used as buffer layers.
Except that N (0 ≦ y ≦ 1) layers 63 are alternately laminated.
It was prepared in the same manner as in Example 1.

In each semiconductor layer, no lattice defects such as pits and cracks were observed.

Since this buffer layer has a superlattice structure similarly to the second embodiment, the buffer layer of the first embodiment is
Further, the effect of alleviating lattice distortion is high.

In the semiconductor light emitting device of this embodiment,
High-efficiency, high-luminance light emission of red, green, and blue was obtained.

In the above embodiment, the semiconductor light emitting devices of the three primary colors of red, green and blue have been described.
By changing the composition of the group I element, light emission from the red to the ultraviolet region can be obtained. For example, when x = 0.75, a yellow semiconductor light emitting element is obtained, when x = 0.9, an orange semiconductor light emitting element is obtained, and when x = 0, an ultraviolet semiconductor light emitting element is obtained.

Although a sapphire substrate was used as the substrate, a semi-insulating ZnO substrate or SiC
A substrate or the like can be used.

[0040]

As is apparent from the above description, according to the present invention, direct transition type InGaN can be stacked while relaxing lattice strain, so that a semiconductor light emitting device which can emit light with high luminance and high efficiency can be obtained. A manufacturing method can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a manufacturing process of a semiconductor light emitting device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a manufacturing process of the semiconductor light emitting device according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a semiconductor light emitting device according to Example 1 of the present invention.

FIG. 4A is a cross-sectional view illustrating a state before an exposed portion of a semiconductor light emitting device according to a second embodiment of the present invention is formed;
(B) is a sectional view showing a buffer layer of the semiconductor light emitting device of Example 2 of the present invention.

FIG. 5A is a cross-sectional view illustrating a state before an exposed portion of a semiconductor light emitting device according to a third embodiment of the present invention is formed;
(B) is a sectional view showing a buffer layer of the semiconductor light emitting device of Example 3 of the present invention.

FIG. 6A is a cross-sectional view illustrating a state before an exposed portion of a semiconductor light emitting device according to a fourth embodiment of the present invention is formed;
(B) is a sectional view showing a buffer layer of the semiconductor light emitting device of Example 4 of the present invention.

FIG. 7 is a diagram showing a relationship between a composition of a group III element of In _x Ga ₁ -xN and a lattice constant, and a relationship with an energy gap.

[Explanation of symbols]

Reference Signs List 1 sapphire substrate 2 buffer layer made of AlN or GaN 3 Si-doped n-In _0.3 Ga _0.7 N layer 4 Mg-doped high resistance In _0.3 Ga _0.7 N layer 5 Si-doped n-In _0.7 Ga _0.3 N layer 6 Mg-doped high resistance In _0.7 Ga _0.3 N layer 7 Si-doped n-InN layer 8 Mg-doped high-resistance InN layer 4 a, 6 a, 8 a p-type region 10, 11, 12 p-type Al electrode 9 n-type Al electrode 40 a, 40 b, 40 c AlN layer / In _y Ga _1-y N
Buffer layer 50a, 50b, 50c composed of a periodic multilayer of (0 ≦ y ≦ 1) layers AlN layer / In _y Ga _1-y N
Buffer layer 60a, 60b, 60c composed of an irregular multilayer body of (0 ≦ y ≦ 1) layers Periodical between AlN or GaN layer and AlN layer / In _y Ga _1-y N (0 ≦ y ≦ 1) layer Buffer layers 41, 51, 61, 63 composed of a multilayer body AlN buffer layers 42, 52, 53, 54, 55, 56, 62 In _y G
a _1-y N (0 ≦ y ≦ 1) buffer layer

Continued on the front page (72) Inventor Hiroyuki Hosoha 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Ken Obayashi 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Sharp Corporation (72 Inventor Toshio Hata 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Naohiro Suyama 22-22 Nagaike-cho, Abeno-ku, Osaka-shi Osaka Prefecture Inside Sharp Corporation (56) References 3-203388 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 33/00 H01S 5/00-5/50 H01L 21/205

Claims (1)

(57) [Claims] 1. A method for manufacturing a semiconductor light emitting device, comprising: laminating a semiconductor layer made of an InGaN-based material on a substrate, wherein the semiconductor layer is made of In _x Ga ₁ -xN (0 ≦ x ≦ 1). Al grown at a lower temperature than the first semiconductor layer
N or In _y Ga _1-y N (0 ≦ y ≦ 1)
A semiconductor layer is formed, and a third semiconductor layer made of In _z Ga _{1 -zN} (0 ≦ z ≦ 1) grown at a higher temperature than the second semiconductor layer is formed on the second semiconductor layer. A method for manufacturing a semiconductor light emitting device, comprising: