JP2803791B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor light emitting device such as a light emitting diode and a semiconductor laser using a wide gap semiconductor.

[0002]

2. Description of the Related Art Fabrication of a semiconductor light emitting device using a semiconductor material capable of emitting light in a blue to green region has been studied.

An InGaAlN-based compound semiconductor has a wide band gap and a direct transition type band structure, and is therefore expected to be applied to blue and green light emitting devices.

[0004] GaN is a direct transition type semiconductor having an energy gap of about 3.39 eV. By using this, a semiconductor light emitting device of ultraviolet light of about 366 nm can be manufactured. Doping a group II atom on this GaN makes it possible to form a light-emitting center having an energy gap corresponding to a blue region, thereby producing a blue light-emitting diode.

[0005] Further, InG obtained by adding In to GaN is used.
aN is a direct transition semiconductor and can emit blue and green light. By using this InGaN,
It is expected that highly efficient light emitting diodes and visible semiconductor lasers will be obtained.

Further, in the above-mentioned GaN or InGaN, Ga contained in the crystal is partially or entirely replaced with Al.
By substituting to the above, the energy gap of the crystal can be increased without substantially changing the lattice constant of the crystal, and the refractive index of the crystal can be lowered. Thus, the crystal in which Ga is substituted by Al and G
By forming a heterojunction using aN or InGaN, a light emitting diode and a semiconductor laser with higher efficiency can be realized.

As a method of growing a GaN layer on a substrate, MOVPE (organic metal compound vapor phase epitaxy) and gas source MBE (molecular beam epitaxy) are used. However, for example, when GaN is doped with a dopant such as Mg to become an acceptor, the GaN becomes high in resistance, and a low-resistance GaN exhibiting p-type conductivity is obtained.
No layers could be obtained. Therefore, a pn junction could not be formed when a light-emitting element was manufactured using GaN, so that a MIS (metal-insulator-semiconductor) structure having poor quantum efficiency and high driving voltage had to be adopted. Did not.

Recently, Japanese journals by H. Amano et al.
l of Applied Physics Vol.28 L2112 (1989)
A semiconductor light emitting device as shown in FIG. 6 has been proposed. In this semiconductor light emitting device, an AlN buffer layer 62, an undoped n-type GaN layer 63, and a GaN layer 64 are laminated on a sapphire substrate 61. The GaN layer 64 includes Mg
Further, a central region 65 of the GaN layer 64 shown by oblique lines in the figure is irradiated with an electron beam 66. Due to the irradiation of the electron beam 66, a change in the electrical characteristics of the irradiated portion 65 is recognized.
Was reported to be a p-type semiconductor layer having a reduced specific resistance of several tens Ω · cm.

[0009] This change in the electrical characteristics is caused by the fact that inert Mg atoms located at interstitial positions in the crystal are excited by electron beam irradiation and are replaced by Ga atoms in the crystal lattice. It is presumed that this occurred due to activation as an acceptor.

[0010]

However, since the above-mentioned electron beam has a high accelerating voltage, the irradiation of the electron beam has an effect on other atoms in the crystal, thereby causing a defect that lattice defects occur. When the thickness of the p-type layer to be formed is large, an electron beam having a higher accelerating voltage is required, so that the lattice defects increase. Thereby, the luminous efficiency decreases. In particular, in the case of a semiconductor laser, when a defect occurs in the optical waveguide region, the reliability is reduced, so that the problem of the lattice defect is large.

Further, in the above semiconductor light emitting device,
Since the growth is completed and the layer on which the acceptor has been doped is irradiated with an electron beam to produce a low-resistance p-type layer, the number of manufacturing steps is increased. Moreover, it is difficult to control the thickness of the p-type layer. In particular, increasing the thickness of the p-type layer is limited because there is a limit on the layer thickness to which the electron beam can reach. Also, it is difficult to control the carrier concentration in the p-type layer.

The present invention has been made to solve the above-mentioned drawbacks, and has no lattice defects in the p-type layer, can emit light with high efficiency, has high reliability, and controls the carrier concentration and the layer thickness of the p-type layer. It is an object of the present invention to provide a method for manufacturing a semiconductor light emitting device which is easy to perform.

[0013]

The present invention provides a p-type In _{1-x
(Ga y Al 1-y)} x N layer (x is 1 or less at greater than 0, y is in a 0 or more and 1 or less) A method of manufacturing a semiconductor device having _{a, In 1-x (Ga y} Al _1-y) and a gas containing nitrogen atoms or nitrogen atoms of the _x N, is supplied to the growth surface alternating with gases containing group III atoms or the group III atoms, and, group III atoms or the Gas containing group III atom
And a dopant that serves as an acceptor together with
A gas contained in the p-type In _1-x (G
_ay Al _1-y ) _x N layer is grown, thereby achieving the above object.

Further, while irradiating the growth surface with light, p
Preferred type _{In 1-x (Ga y Al} 1-y) is grown with _x N layer.

[0015]

According to the present invention, the growth surface on the substrate has In
_{1-x (Ga y Al 1} -y) and a nitrogen atom and the group III atoms contained in _x N is supplied alternately _{In 1-x (Ga y Al} 1-y) is grown with _x N layer. At that time, an acceptor is supplied simultaneously with either a nitrogen atom or a group III atom. As a result, migration of the dopant is increased, so that the dopant can surely enter a lattice position that can be an acceptor. Growth Simultaneously the In _1-x (Ga _y A
Since l _{1-y) x} N layer is a p-type _{In 1-x (Ga y Al} 1-y) x N layer, it is easy to control the thickness and carrier concentration.

When the growth surface is irradiated with light, the energy can further increase the migration.

[0017]

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

Embodiment 1 FIG. 1 is a longitudinal sectional view showing a semiconductor light emitting device according to Embodiment 1 of the present invention.

This semiconductor device has an AlN buffer layer 2 and an n-type In on an (0001) plane of a sapphire substrate 1.
_{1-w (Ga z Al 1} -z) w N layer 3 (w is 1 or less at greater than 0,
z is 0 or more and 1 or less), p-type In _1-x (Ga _y Al
_1-y ) _x N layers 4 (x is greater than 0 and 1 or less, and y is 0 or more and 1 or less) are laminated. The p-type In _1-x (G
_{a y Al 1-y) x} N layer 4 and the n-type In _1-w (Ga _z A
l _{1-z) w} N layer 3, n-type _{In 1-w (Ga z Al} 1-z) w N layer 3 are partially removed to expose, exposed n-type an In _{1- w (Ga z Al 1-z} ) over the _w n layer 3, is provided an n-type Al electrode 5, p-type in _1-x Ga _y Al remaining
A p-type Al electrode 6 is provided on _{1-y) x} N layer 4.

This semiconductor light emitting device is manufactured as follows. As a method for growing each of the above semiconductor layers, MO
VPE or gas source MBE is preferred. The following compounds can be used as the source of the atoms and the dopant material constituting 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), etc. N source: ammonia (NH ₃ ) Dopant gas: silane (SiH ₄ ) (for n-type dopant) and biscyclopentadienyl magnesium (C
p ₂ Mg) (for p-type dopant) and the like.

First, the wafer-shaped sapphire substrate 1 is thermally cleaned at a substrate temperature of 1150 ° C. Thereafter, the substrate temperature is lowered to 600 ° C., and the (0001)
The surface on the AlN buffer layer 2 is grown, followed by raising the substrate temperature to 800 ° C. n-type _{In 1-w (Ga z Al} 1-z) growing a _w N layer 3. The above-mentioned buffer layer 2, n-type In _1-w (G
a _z Al _1-z ) _{w The} substrate 1 on which the N layer 3 is laminated is irradiated with an Ar laser, for example, by the above-described TMG, TMI and Cp.
While alternately supplying ₂ Mg and supplying NH ₃ gas, p
-Type _{In 1-x (Ga y Al} 1-y) is grown with _x N layer 4.

FIG. 5 shows that the p-type In
Each atom constituting the _{1-x (Ga y Al 1} -y) x N layer 4 is a schematic view showing a state where the layer 4 is supplied onto the substrate is grown. In this figure, an example is shown in which a dopant 51 activated as an acceptor when arranged at a lattice position of a group III atom 52 is used. Examples of such a dopant 51 include the above-mentioned Mg and the like.

[0024] In _{In 1-x (Ga y Al} 1-y) x N layer 4,
The dopant 51 is a group III atom 5 of In, Ga, or Al.
Activated as an acceptor if substituted to a second position, whereby the _{In 1-x (Ga y Al} 1-y) conductivity type _x N layer 4 is a p-type. When the dopant 51 is arranged at an interstitial position in the crystal, the dopant 51 is not activated as an acceptor.

[0025] When growing the p-type _{In 1-x (Ga y Al} 1-y) x N layer 4 alternately supplies to the growth surface and a group III atoms 52 and nitrogen atoms 53. At this time, the dopant 51 is supplied to the growth surface simultaneously with the group III atom 52. While the group III atom 52 and the dopant 51 are being supplied, the supply of the nitrogen atom 53 is stopped. As a result, migration of these atoms on the growth surface increases, and the dopant 51 can be reliably taken into a lattice position that can function as an acceptor. Therefore, the dopant 51 does not enter the interstitial position, and the p-type
the _{n 1-x (Ga y Al} 1-y) x N layer 4, the lattice defects do not occur such as occur when performing electron beam irradiation.

Since the barrier between the diffusion of adsorbed molecules on the substrate surface and the incorporation of dopants into lattice positions is from 1 to several eV, irradiation with light having a band wavelength corresponding to this energy causes further migration of atoms. Promoted. That is, when light irradiation such as a laser is performed when the dopant 51 is supplied, the migration is further promoted. In this embodiment, the wavelength 51
An Ar laser of 4 to 528 nm was used.

The p-type _{In 1-x (Ga y Al} 1-y) x N layer 4 after the formation, by dry etching, a p-type In _1-x (Ga _y A
l _{1-y) x} N layer 4 an n-type _{In 1-w (Ga z Al} 1-z) w N layer 3
Partially removed to a depth that reaches the inside of the. On the exposed n-type _{In 1-w (Ga z Al} 1-z) w N layer 3, and depositing a n-type Al electrode 5, the remaining p-type _{In 1-x (Ga y Al} 1-y) x
A p-type Al electrode 6 is deposited on the N layer 4. Each Al electrode 5,
After the formation of the substrate 6, the wafer-shaped substrate 1 is divided into chips by dicing to form semiconductor light emitting devices.

The details of the semiconductor layers 2, 3 and 4 in this embodiment are as follows.

The buffer layer 2: AlN, thickness 500 Å, n-type _{In 1-w (Ga z Al} 1-z) w N layer 3: In _0.4 Ga _0.6
N, thickness 3 [mu] m, p-type _{In 1-x (Ga y Al} 1-y) x N layer 4: In _0.4 Ga _0.6
N, thickness 1 [mu] m, p-type _{In 1-x (Ga y Al} 1-y) x N layer 4 in the p-type carrier concentration of: 5 × 10 ¹⁷ cm ^-3.

The size of the chip is 300 μm × 300 μm
And

The semiconductor light emitting device of this embodiment has a wavelength of 470
Highly efficient emission of blue light of nm was obtained.

Embodiment 2 FIG. 2 is a longitudinal sectional view showing a semiconductor light emitting device according to Embodiment 2 of the present invention.

This semiconductor device is formed by forming an AlN
Buffer layer 22, n-type _{In 1-w (Ga z Al} 1-z) w N layer 2
3, p-type _{In 1-x (Ga y Al} 1-y) x N layer 24 are stacked. The substrate 21 n-type electrode 25 is formed on the entire surface, the p-type _{In 1-x (Ga y Al} 1-y) x N layer p-type Al electrode 26 on 24 is formed.

In the semiconductor light emitting device of the second embodiment, the same source as that of the first embodiment can be used.
By the supply of the group III atoms and dopant feed and the nitrogen atoms are alternately performed an Ar laser to the growth surface while irradiating the growth surface of substrate 21, p-type In _1-x (Ga _y
An Al _1-y ) _x N layer 24 is grown. Wafer-shaped substrate 2
After the electrodes 25 and 26 are formed, 1 is divided into chips by dicing to be semiconductor light emitting elements.

In this embodiment, the substrate 21 is n
A ZnO substrate was used, and In was used as the n-type electrode 25. The details of each of the semiconductor layers 22, 23 and 24 laminated on the substrate 21 are as follows.

Buffer layer 22: n-type AlN, thickness 500
Å, n-type _{In 1-w (Ga z Al} 1-z) w N layer 23: In _0.4 Ga
_0.6 N, a thickness of 3 [mu] m, p-type _{In 1-x (Ga y Al} 1-y) x N layer 24: In _0.4 Ga
_0.6 N, a thickness of 1 [mu] m, p-type _{In 1-x (Ga y Al} 1-y) x N layer of p-type in the 24 carrier concentration: 5 × 10 ¹⁷ cm ^-3.

The semiconductor light emitting device of this embodiment has a wavelength of 470
nm blue light emission was obtained, and light emission with higher efficiency than that of Example 1 was obtained.

Embodiment 3 FIG. 3 is a longitudinal sectional view showing a semiconductor light emitting device according to Embodiment 3 of the present invention.

This semiconductor device is formed by forming AlN on a substrate 31.
Buffer layer 32, n-type _{In 1-w (Ga z Al} 1-z) w N cladding layer 37, an undoped _{In 1-s (Ga t Al} 1-t) s N active layer 38 (s is 1 greater than 0 hereinafter, t is 0 or more and 1 or less), p-type _{in 1-x (Ga y Al} 1-y) x N cladding layer 3
9, p-type In _1-u (Ga _v Al _1-v ) _u N layer 310 (u is 0
Larger than 1 and v is 0 or more and 1 or less) and Si
An N insulating film 311 is formed by lamination. The composition ratios z and y are less than t. The SiN insulating film 311 has a width of 10
The μm stripe groove 313 is formed of p-type In _1-u (Ga _v Al
_1-v) is formed with a depth reaching the surface of the _u N layer 310, p-type Al electrode 312 is formed thereon, the substrate 31
On the side, an n-type electrode 35 is formed on the entire surface.

In the semiconductor light emitting device of the third embodiment, the same source as that of the first embodiment can be used.
While irradiating the growth surface with an Ar laser, the TMI, TM
G, TMA, and Cp ₂ by Mg and feed supply and NH ₃ in are performed alternately, p-type In _1-x (Ga _y Al
_{1-y) x} N cladding layer 39, p-type In _1-u (Ga _v A
l _1-v ) _u N layer 310 is grown. SiN insulating film 311
Are formed by plasma CVD, and the stripe grooves 3 are formed by photolithography and selective etching.
13 are formed. A resonator is formed by dry etching. After the formation of the resonator, the wafer-shaped substrate 31 is divided into chips to form a semiconductor laser.

In this embodiment, the substrate 31 is n
An In-type ZnO substrate was used, and In was used as the n-type electrode 35. Details of each of the semiconductor layers 32, 37, 38, 39 and 310 are as follows.

Buffer layer 32: n-type AlN, thickness 500
Å, n-type _{In 1-w (Ga z Al} 1-z) w N cladding layer 37: n-type In _0.4 Al _0.6 N, a thickness of 2 [mu] m, an undoped _{In 1-s (Ga t Al} 1-t) s N activity layer 38: undoped In _0.4 Ga _0.6 N, a thickness of 0.1 [mu] m, p-type _{In 1-x (Ga y Al} 1-y) x N cladding layer 39: p-type In _0.4 Al _0.6 N, a thickness of 1 [mu] m, p-type In _1-u (Ga _v Al _1-v ) _u N layer 310: p-type In
_0.4 Ga _0.6 N, a thickness of 0.2 [mu] m, p-type _{In 1-x (Ga y Al} 1-y) x N cladding layer 39, p-type _{In 1-u (Ga v Al} 1-v) in _u N layer 310 P-type carrier concentration: 5 × 10 ¹⁷ cm ⁻³ .

The size of the chip is 300 μm × 1000 μm
m.

In the semiconductor light emitting device of this embodiment, laser oscillation was obtained by pulse driving at 77K.

Example 4 FIG. 4 is a longitudinal sectional view showing a semiconductor light emitting device according to Example 4 of the present invention.

This semiconductor device is formed on a substrate 41 by AlN.
Buffer layer 42, n-type _{In 1-w (Ga z Al} 1-z) w N cladding layer 47, an undoped _{In 1-s (Ga t Al} 1-t) s N layer 48, p-type In _1-x (Ga _y Al _1-y ) _x N cladding layer 49
And a p-type In _1-u (Ga _v Al _1-v ) _u N layer 410 are laminated. The composition ratios z and y are less than t. p-type _{In 1-x (Ga y Al} 1-y) x N in the cladding layer 49 and the p-type _{In 1-u (Ga v Al} 1-v) u N layer 410, a ridge of width 10μm projecting stripes The ridge 415 is formed on both sides of the ridge 415.
An s layer 414 is formed. p-type In _1-u (Ga _v Al
_1-v) p-type Al electrode 412 covers the _u N layer 410 and the n-type GaAs layer 414 is formed, on the substrate 41 side n-type electrode 45 is formed on the entire surface.

The semiconductor light emitting device of Example 4 is manufactured as follows. First, on the substrate 41, the AlN buffer layer 42 p-type _{In 1-u (Ga v Al} 1-v) u N layer 410
Are laminated in the same manner as in the third embodiment.

[0048] p-type _{In 1-u (Ga v Al} 1-v) u N layer 410
An Al ₂ O ₃ film (not shown) is further formed thereon, and a width of 10 mm is formed by photolithography and dry etching.
Leave a μm stripe. Al remaining in stripes
The ₂ O ₃ film as a mask, p-type _{In 1-u (Ga v Al} 1-v) u N
Layer 410 and the p-type _{In 1-x (Ga y Al} 1-y) x N layer 49
Is etched to form a ridge portion 415. After etching, n-type GaAs is formed by MBE or MOVPE.
The s layer 414 is grown, and the Al ₂ O ₃ film and the n-type GaAs layer 414 remaining on the upper surface of the ridge portion 415 are removed by photolithography and selective etching.
A resonator is manufactured by dry etching. After the formation of the resonator, the wafer-shaped substrate 41 is divided into chips to form a semiconductor laser.

In this embodiment, as the substrate 41, n
In was used as the n-type electrode 45 using a type ZnO substrate. Details of each of the semiconductor layers 42, 47, 48, 49 and 410 are as follows.

Buffer layer 42: n-type AlN, thickness 500
Å, n-type _{In 1-w (Ga z Al} 1-z) w N cladding layer 47: n-type In _0.4 Al _0.6 N, a thickness of 2 [mu] m, an undoped _{In 1-s (Ga t Al} 1-t) s N activity layer 48: undoped In _0.4 Ga _0.6 N, a thickness of 0.1 [mu] m, p-type _{In 1-x (Ga y Al} 1-y) x N cladding layer 49: p-type In _0.4 Al _0.6 N, a thickness of 1 [mu] m, p-type In _1-u (Ga _v Al _1-v ) _u N layer 410: p-type In
_0.4 Ga _0.6 N, a thickness of 0.2 [mu] m, p-type _{In 1-x (Ga y Al} 1-y) x N cladding layer 49, p-type _{In 1-u (Ga v Al} 1-v) in _u N layer 410 P-type carrier concentration: 5 × 10 ¹⁷ cm ⁻³ .

The size of the chip is 300 μm × 1000 μm
m.

In the semiconductor light emitting device of this example, laser oscillation was obtained by pulse driving at 77K.

In the second, third and fourth embodiments, the n-type ZnO substrate is used as the substrates 21, 31 and 41, but an n-type SiC substrate or the like may be used instead. In the case where an n-type SiC substrate or the like is used, n-type Ni / A
It is preferable to use a u electrode.

[0054]

According to the present invention, it is possible to provide a highly efficient and highly reliable semiconductor light emitting device having no lattice defect in the p-type InGaAlN layer.

The semiconductor light emitting device of the present invention can be manufactured with a small number of steps, and the thickness and carrier concentration of the p-type InGaAlN layer can be easily controlled.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a semiconductor light emitting device of Example 1 of the present invention.

FIG. 2 is a longitudinal sectional view showing a semiconductor light emitting device according to a second embodiment of the present invention.

FIG. 3 is a longitudinal sectional view showing a semiconductor light emitting device according to a third embodiment of the present invention.

FIG. 4 is a longitudinal sectional view showing a semiconductor light emitting device of Example 4 of the present invention.

5 is a schematic view showing a step of growing p-type _{In 1-x (Ga y Al} 1-y) x N layer.

FIG. 6 is a schematic view showing a conventional semiconductor light emitting device.

[Explanation of symbols]

1 substrate 4 p-type _{In 1-x (Ga y Al} 1-y) x N layer 21 substrate 24 p-type _{In 1-x (Ga y Al} 1-y) x N layer 31 substrate 39 p-type an In _1-x ( _{Ga y Al 1-y) x} N cladding layer 41 substrate 49 p-type _{In 1-x (Ga y Al} 1-y) x N cladding layer 51 dopant 52 III group atom 53 nitrogen atoms

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor ▲ Yoshi ▼ Tomohiko 22-22-22, Nagaikecho, Abeno-ku, Osaka, Osaka Inside Sharp Corporation (72) Inventor Takeshi Obayashi 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Toshio Hata 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Prefecture Inside Sharp Corporation (72) Inventor Naohiro Suyama 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Sharp Corporation (58 ) Surveyed field (Int.Cl. ⁶ , DB name) H01L 33/00

Claims (2)

(57) [Claims] 1. A p-type _{In 1-x (Ga y Al} 1-y) x N layer (x
1 or less at greater than 0, y is a method of manufacturing a semiconductor device having a at which) 0 to 1 _{inclusive, In 1-x (Ga y} Al
_1-y) and a gas containing nitrogen atoms or nitrogen atoms of the _x N, is supplied to the growth surface alternating with gases containing group III atoms or the group III atoms, and, group III atoms or the III
Acceptor with any of the gases containing group atoms
The method of manufacturing a semiconductor device comprising supplying a gas containing a dopant to be over to the growth surface growing the p-type _{In 1-x (Ga y Al} 1-y) x N layer. 2. The method according to claim 1, wherein the growth surface is irradiated with light while the p-type
_{n 1-x (Ga y Al} 1-y) The method as claimed in claim 1, further comprising a step of growing the _x N layer.