JP2003318117A - Method for manufacturing compound semiconductor device and semiconductor laser element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a compound semiconductor device which can accurately control the thickness of a compound semiconductor layer. <P>SOLUTION: A first periodic structure 21 is formed by repeating a plurality of times a first composition compound semiconductor layer 22 and a second composition compound semiconductor layer 23 on a wafer in a predetermined growing time. A second periodic structure 24 is formed by repeatedly growing a first composition compound semiconductor layer 22' in the same growing time as the growing time of the layer 22 and repeatedly growing a second composition compound semiconductor layer 25 in a different growing time from that of the layer 23. The spatical period d<SB>1</SB>of the first structure 21 and the spatical period d<SB>2</SB>of the second structure 24 are measured by an X-ray diffraction method. The growing rates of the second composition compound semiconductor layers 23, 25 is obtained based on a difference (d<SB>2</SB>-d<SB>1</SB>), and the growing rate of the first composition compound semiconductor layers 22, 22' is obtained. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a compound semiconductor device manufacturing method for manufacturing a device including a compound semiconductor layer. The present invention also relates to a semiconductor laser device manufactured by such a manufacturing method.

[0002]

2. Description of the Related Art In recent years, C has been used as a compound semiconductor device.
D (Compact disc), MD (Mini disc)
The demand for semiconductor laser devices used for pickups for automobiles is increasing more and more, and there is a demand for semiconductor laser devices with less characteristic variation and excellent reliability. A double heterojunction structure was used as the basic structure of the semiconductor laser device, but with the demand for higher optical output and lower threshold current, for example, the carrier confinement region and the optical confinement region were separated. , Separate confinement heterostructure (SC
H: separate confinement heterostructure) or multiple quantum wells (MQW: mu) with quantum wells formed in the active region.
Lti quantum well) structure has come to be used. The thickness of the thinnest semiconductor layer in these laminated structures is several tens of Å to several hundred Å.Therefore, in place of the liquid phase epitaxy method that has been generally used as a semiconductor layer forming method until now, layer thickness control Easy metal organic chemical vapor deposition (MOCVD:
A vapor phase epitaxy method such as a metalorganic chemical vapor deposition (MBE) method or a molecular beam epitaxy (MBE) method is used.

For example, a ridge type semiconductor laser device is shown in FIG.
It is manufactured as shown in FIGS.
First, as shown in FIG.
N-type GaAs buffer layer (layer thickness 0.5 μm) 2, n-type Al _x Ga _1-x As first cladding layer (x = 0.46, layer thickness 2.7 μm) 3, n-type on a GaAs substrate 1 Al _x
Ga _1-x As second cladding layer (x = 0.48, layer thickness 0.2 μm) 4, non-doped Al _x Ga _1-x As first
Optical guide layer (x = 0.35, layer thickness 280Å) 5, non-doped Al _x Ga _1-x As quantum well active layer 6, non-doped Al _x Ga _1-x As second optical guide layer (x = 0.3
5, layer thickness 280Å) 7, p-type Al _x Ga _1-x As 1st
Clad layer (x = 0.48, layer thickness 0.2 μm) 8, p-type GaAs etching stop layer (layer thickness 26Å) 9, p-type Al _x Ga _1-x As second clad layer (x = 0.48,
A layer thickness of 1.3 μm) 10 and a p-type GaAs cap layer (layer thickness of 0.75 μm) 11 are sequentially grown. Quantum well active layer 6
Is composed of a well layer, a barrier layer, and a guide layer having different thicknesses (mixed crystal ratio x) and having a thickness of several tens of liters. Next in FIG.
As shown in FIG. 1B, a striped resist 12 extending in a direction perpendicular to the plane of FIG. 1B is formed by photolithography or the like, and then the p-type GaAs cap layers 11 and p on both sides of the resist 12 are formed. Type Al _x Ga
_{The 1-x} As second cladding layer 10 is removed by etching. As a result, the p-type GaAs cap layer 11 and p
A ridge made of a part of the type Al _x Ga _1-x As second cladding layer 10 is formed. After removing the resist, a high resistance or n-type Al _{x is formed on} both sides of the ridge by MOCVD again as shown in FIG.
Ga _1-x As current blocking layer (x = 0.7, layer thickness 1.
0, 13, n-type GaAs current blocking layer (layer thickness 0.
3 μm) 14 and a p-type GaAs flattening layer 15 are laminated. Next, a resist (not shown) is formed by a photolithography method on a portion other than on the ridge, and the current block layer 1 is formed.
3, 14, and unnecessary portions on the ridge of the p-type planarization layer 15 are removed by etching. After removing the resist, a p-type GaAs contact layer (layer thickness 50 μm) 16 is grown as shown in FIG. Then, the n-type electrode 18 is formed on the back surface of the wafer and the p-type electrode 17 is formed on the front surface of the wafer.

Generally, in the MOCVD method and the MBE method, the thickness of the semiconductor layer is controlled by setting the growth time. Specifically, the material of the semiconductor layer used for the compound semiconductor device is deposited in advance on the monitor wafer, and the thickness of the deposited layer is divided by the growth time to obtain the growth rate. Then, at the stage of actually producing the compound semiconductor device, the growth time is set based on the above growth rate so that the semiconductor layer is grown to a predetermined target layer thickness.

Here, as a conventional method for measuring the thickness of the deposited layer, i) a method of cleaving a wafer and directly observing a cross section of the deposited layer with a scanning electron microscope, or ii) deposition There is known a method in which a layer is selectively etched and the level difference is measured by a contact type step meter. iii) Further, JP-A-1-98215 discloses a method of nondestructively measuring the layer thickness of a thin film crystal by a photoluminescence method. According to this method, a quantum well structure in which a GaAs well layer is sandwiched between AlGaAs barrier layers is formed on an epitaxial substrate, and the emission wavelength from the well layer is measured by the photoluminescence method. Since this emission wavelength corresponds to the thickness of the well layer, the thickness of the well layer can be obtained from the emission wavelength.
If the thickness of the well layer is in the range of 50Å to 100Å, the thickness of the well layer can be calculated particularly accurately.

[0006]

In order to reduce the variation in the characteristics of the semiconductor laser device, it is important to accurately control the thickness of each semiconductor layer forming the laminated structure. For example, a semiconductor laser device is increasing in output as a light source for an optical disc for speeding up recording / reproducing. However, in a high output semiconductor laser device, in order to improve coupling efficiency with an optical system, a direction perpendicular to the heterojunction surface is used. It is important to control the radiation angle so as to reduce the radiation angle (hereinafter referred to as “vertical radiation angle”) of 16 ° to 19 ° and to reduce the variation of the vertical radiation angle. In the SCH and MQW structures currently used in high-power semiconductor laser devices, the vertical emission angle depends on the refractive index difference between the multiple quantum well active layer and the cladding layer and the thickness of the guide layer that performs optical confinement. There is. The thickness of the well layer, the barrier layer, and the guide layer that form the multiple quantum well active layer is set to several tens of liters, and the thickness of the guide layer is usually set in the range of 270 to 300 liters. The thickness must be controlled on the order of a few Å.
For that purpose, the growth rates of these layers must be accurately determined.

However, in the method of cleaving the wafer and observing the cross section of the deposited layer with a scanning electron microscope to measure the layer thickness (above i), the layer thickness is at least 0.5 μm or more in order to enable observation. Therefore, the growth time of the guide layer is set based on the growth rate obtained from the layer thickness that is about 20 times the actual thickness of the guide layer. This method cannot avoid an error in reading the layer thickness with an electron microscope, and there is a gap between the growth rate at the actual thickness of the guide layer and the growth rate at the observation layer thickness. To do. Therefore, it is difficult to control the layer thickness on the order of Å based on this method.

A method in which the deposited layer is selectively etched and the step difference is measured by a contact type step meter (above ii)
Is not applicable if there is no suitable etchant for selectively etching only the guide layer of the deposited layers.

Further, the method disclosed in Japanese Patent Laid-Open No. 1-98215 (above iii) cannot be applied to a well layer made of a ternary mixed crystal such as AlGaAs. That is, in the case of a well layer formed of a ternary mixed crystal, the thickness and composition (Al mixed crystal ratio) of the well layer are factors that determine the wavelength of light emitted from the well layer, and they change independently. Therefore, in the above method, this
Two factors cannot be determined. Further, when the well layer has a thickness of about 200 Å, the change in the emission wavelength with respect to the thickness of the well layer becomes small, so that the measurement error due to the photoluminescence measurement becomes large.

For a periodic structure, such as a multiple quantum well (MQW) structure, in which a plurality of types of compound semiconductor layers having different compositions are repeatedly laminated a plurality of times at a constant period, satellite reflection of X-ray diffraction is used. Spatial period measurement methods have been established. However, this measuring method cannot directly know the thickness of each compound semiconductor layer.

Therefore, an object of the present invention is to provide a compound semiconductor device manufacturing method capable of accurately controlling the thickness of a compound semiconductor layer.

Another object of the present invention is to provide a semiconductor laser device manufactured by such a manufacturing method and having less variation in radiation characteristics, especially variation in vertical radiation angle.

[0013]

In order to solve the above problems, the compound semiconductor device manufacturing method of the present invention is premised on the first composition having a different composition which is to be grown to a target layer thickness by a predetermined growth method. A device including a compound semiconductor layer having a second composition is manufactured.

The process of determining the growth time for each compound semiconductor layer includes the following steps. In the first step, a compound semiconductor layer having a first composition and a compound semiconductor layer having a second composition are repeatedly grown on a wafer a plurality of times with constant growth times to form a first periodic structure.
In the next step, the compound semiconductor layer having the first composition is formed on the wafer at the same growth time as that of the compound semiconductor layer having the first composition having the first periodic structure, and the compound semiconductor layer having the second composition is formed on the wafer. And a second composition compound semiconductor layer having a periodic structure of
Form a periodic structure of. In the next step, the spatial period of the first periodic structure and the spatial period of the second periodic structure are measured by the X-ray diffraction method. In the last step, the growth rate of the compound semiconductor layer of the second composition is obtained based on the difference between the measured spatial period of the first periodic structure and the spatial period of the second periodic structure, and The growth rate of the compound semiconductor layer of one composition is obtained.

According to the method of manufacturing a compound semiconductor device of the present invention, the growth rates of the compound semiconductor layer of the first composition and the compound semiconductor layer of the second composition contained in the device to be manufactured can be accurately obtained. Therefore, the first
It is possible to accurately control the thicknesses of the compound semiconductor layer having the composition and the compound semiconductor layer having the second composition to the target layer thickness.

In the compound semiconductor device manufacturing method of one embodiment, the final step is performed as follows. That is, first, the difference between the measured spatial period of the first periodic structure and the spatial period of the second periodic structure is calculated as the growth of the compound semiconductor layer of the second composition when the first periodic structure is formed. The growth rate of the compound semiconductor layer of the second composition is obtained by dividing by the difference between the time and the growth time of the compound semiconductor layer of the second composition when the second periodic structure is formed. Next, the measured spatial period of the first periodic structure or the spatial period of the second periodic structure, and the second period calculated from the growth rate of the compound semiconductor layer of the second composition in the periodic structure. Based on the difference between the composition and the thickness of the compound semiconductor layer, the first
The growth rate of the compound semiconductor layer having the composition is obtained.

According to the compound semiconductor device manufacturing method of this embodiment, specifically, the growth rates of the compound semiconductor layer of the first composition and the compound semiconductor layer of the second composition contained in the device to be manufactured are accurately obtained. be able to. Therefore, the thicknesses of the compound semiconductor layer having the first composition and the compound semiconductor layer having the second composition can be accurately controlled to the target layer thicknesses.

In the compound semiconductor device manufacturing method of one embodiment, the first periodic structure and the second periodic structure are successively formed on the same wafer in this order. Then, measurement data obtained by combining the two periodic structures is obtained by an X-ray diffraction method, and the second periodic structure is etched and removed. After that, the first layer left on the wafer is subjected to an X-ray diffraction method.
The spatial measurement of the first periodic structure is obtained by obtaining the measurement data of the periodic structure of. Further, the measurement data of the first periodic structure is subtracted from the measurement data of the two periodic structures to obtain the spatial period of the second periodic structure.

In the compound semiconductor device manufacturing method of this one embodiment, since the first periodic structure and the second periodic structure are successively formed on the same wafer in this order, the two periodic structures are formed. For this purpose, the actual growth process (work) using a metal organic chemical vapor deposition (MOCVD) apparatus or a molecular beam epitaxy (MBE) apparatus is required only once. Therefore, the number of steps required to obtain the growth rates of the compound semiconductor layer of the first composition and the compound semiconductor layer of the second composition can be reduced.

To prepare a compound semiconductor device,
There are n types of compound semiconductor layers (n is 3
There are cases where there is a natural number above). In the compound semiconductor device manufacturing method according to one embodiment, n kinds of periodic structures formed by repeatedly growing two different kinds of compound semiconductor layers therein at a constant growth time a plurality of times, that is, a compound whose growth time is to be determined Only the number of types of semiconductor layers is formed.
In addition, "type" means the type by composition.

According to the compound semiconductor device manufacturing method of this embodiment, the growth rates of the n kinds of compound semiconductor layers can be accurately obtained by the method described above.
Therefore, when manufacturing an actual compound semiconductor device, the thickness of the compound semiconductor layer can be accurately controlled to the target layer thickness.

In the compound semiconductor device manufacturing method of one embodiment, the composition and thickness of each compound semiconductor layer are limited as follows. That is, the compound semiconductor layer of the first composition contained in the first and second periodic structures has a thickness of 70Å to 100.
Å Al _x Ga _1-x As (where x = 0.11). The compound semiconductor layer of the second composition included in the first periodic structure has a thickness of 50 Å to 60 Å Al _x G.
a _1−x As (where x = 0.35). The compound semiconductor layer of the second composition included in the second periodic structure has a thickness of 90Å to 110Å Al _x G.
a _1−x As (where x = 0.35).

The composition and thickness of each compound semiconductor layer are used for the active layer (well layer, barrier layer, guide layer) of the semiconductor laser device. Therefore, according to the compound semiconductor device manufacturing method of this embodiment, the active layer (well layer, barrier layer, guide layer) of the semiconductor laser device is formed.
Growth rate can be obtained accurately. As a result, it is possible to fabricate a semiconductor laser device with little variation in radiation characteristics, especially variation in vertical radiation angle.

The semiconductor laser device of the present invention is a semiconductor laser device having a separated confinement hetero structure and a multiple quantum well structure manufactured by the compound semiconductor device manufacturing method of the present invention, which is made of an AlGaAs material and has an oscillation wavelength of 780 nm to 780 nm. It is within the range of 786 nm.

According to the semiconductor laser device of the present invention, variations in radiation characteristics, particularly variations in vertical radiation angle, can be reduced as compared with the prior art. For example, the vertical radiation angle distribution is 16 °
It can be easily suppressed within the range of 19 ° to 19 °. As a result, the device yield is increased.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the embodiments shown in the drawings.

The compound semiconductor device manufacturing method of the present invention is applied to manufacture the ridge type semiconductor laser device (SCH-MQW laser device) shown in FIG. In FIG. 2D, 1 is an n-type GaAs substrate, 2 is n
Type GaAs buffer layer (layer thickness 0.5 μm), 3 is n type A
1 _x Ga _1-x As first cladding layer (x = 0.46, layer thickness 2.7 μm), 4 is an n-type Al _x Ga _1-x As second cladding layer (x = 0.48, layer thickness 0) .2 μm), 5 is a non-doped Al _x Ga _1-x As first optical guide layer (x = 0.
35, layer thickness 280 Å), 6 is undoped Al _x Ga
_1-x As quantum well active layer, 7 is non-doped Al _x Ga
_1-x As second light guide layer (x = 0.35, layer thickness 280
Å), 8 is p-type Al _x Ga _1-x As first cladding layer (x = 0.48, layer thickness 0.2 μm), 9 is p-type GaAs
Etching stop layer (layer thickness 26Å), 10 is p-type Al
_x Ga _1-x As second cladding layer (x = 0.48, layer thickness 1.3 μm), 11 is a p-type GaAs cap layer (layer thickness 0.75 μm), 13 is n-type Al _x Ga _1-x As. Current blocking layer (x = 0.7, layer thickness 1.0 μm), 14 is n
-Type GaAs current blocking layer (layer thickness 0.3 μm), 15 p-type GaAs flattening layer (layer thickness 0.7 μm), 16 p-type GaAs contact layer (layer thickness 50 μm), 17 p-electrode, 18 n The electrodes are shown respectively. The layer thickness shown in each parenthesis above is the target layer thickness. The quantum well active layer 6 is
A non-doped Al _x Ga _1-x As well layer with a thickness of several tens of liters having different compositions (mixed crystal ratio x), non-doped Al _x G
a _1-x As barrier layer, non-doped Al _x Ga _1-x A
It consists of a stack of s guide layers.

The semiconductor laser device made of this AlGaAs material is designed to have an oscillation wavelength of 780 nm to 786 nm and a vertical radiation angle distribution of about 16 ° to 19 °. Each of the layers 2 to 11 and 13 to 16 is crystal-grown by the MOCVD method so as to have the target layer thickness shown in each parenthesis above. AlGaAs quantum well active layer 6, Al
GaAs guide layers 5, 7, AlGaAs cladding layers 3,
In order to control the thicknesses of the 4, 8, 10, and the GaAs cap layer 11 to be the target layer thicknesses, it is necessary to accurately obtain the growth rates of those layers before actual crystal growth. There is.

(First Example) In this example, the quantum well active layer 6 is an Al _x Ga _1-x As well layer (x = 0.11, layer thickness 80 Å), an Al _x Ga _1-x As barrier layer ( x = 0.
35, layer thickness 50 Å), and an Al _x Ga _1-x As guide layer (x = 0.35, layer thickness 300 Å), and the growth rates of these layers are determined. The layer thickness shown in each parenthesis above is the target layer thickness (the same applies hereinafter). In this example, the well layer, the barrier layer, and the guide layer have different compositions (mixed crystal ratio x) from each other. The barrier layer and the guide layer have the same mixed crystal ratio x of 0.35 and are different from each other only in the target layer thickness. Therefore, the compound crystal layer of the first composition is mixed with the mixed crystal ratio x
= 0.11 Al _x Ga _1-x As layer and the compound semiconductor layer of the second composition is Al _x Ga with mixed crystal ratio x = 0.35.
As the _1-x As layer, the growth rates of these two types of layers are obtained.

Specifically, as shown in FIGS. 3A and 3B, M is formed on an n-type GaAs substrate 19 as a wafer.
An Al _x Ga _1-x As clad layer (x = 0.50, layer thickness 0.2 μm) 20 is formed by the OCVD method, and subsequently, Al _x Ga as a compound semiconductor layer of the first composition is formed.
_1-x As layer (x = 0.11, layer thickness 80Å) 22 and second
An Al _x Ga _1-x As layer (x = 0.35, layer thickness 50Å) 23 as a compound semiconductor layer having a composition is repeatedly grown eight times at constant growth times to form a first periodic structure 21. .

On the other hand, as shown in FIGS. 3C and 3D, the MOC is formed on the n-type GaAs substrate 19 'as another wafer.
By the VD method, the Al _x Ga _1-x As cladding layer (x =
0.50, layer thickness 0.2 μm) 20 ', and subsequently,
_Al x _{Ga 1-x} A as a compound semiconductor layer of the first composition
s layer (x = 0.11, layer thickness 80 Å) 22 'and _Al x _{Ga 1-x} As layer as a compound semiconductor layer of a second composition (x =
0.35 and layer thickness 100 Å) 25 are repeatedly grown eight times with a constant growth time to form the second periodic structure 24. It should be noted here that, as can be seen from the same target layer thickness, the growth time of the Al _x Ga _1-x As layer 22 and the Al
_While the growth time of the _x Ga _1-x As layer 22 ′ is set to be the same, as can be seen from the difference in the target layer thickness, Al _x Ga
_1-x growth time As layer 23 and the _Al x _{Ga 1-x} growth time As layer 25 is to have a different setting.

Next, to measure the spatial period _{d 1} of the first periodic structure 21 by X-ray diffraction method, the spatial period _{d 2} of the second periodic structure 24 respectively.

As shown in FIG. 4, the measurement data of this X-ray diffraction method (observed waveform) includes a GaAs substrate peak, an AlGaAs peak, and a satellite peak. From the satellite peak spacing d to the first periodic structure 21
Spatial period d ₁ of the second periodic structure 24
₂ can be obtained respectively.

Next, the spatial period _{d 2} the spatial period _{d 1} and the second periodic structure 24 of the first periodic structure 21 was measured
Based on the difference between the Al _x Ga _1-x As layers 23 and 2 having a mixed crystal ratio x = 0.35 as the compound semiconductor layer of the second composition.
Find the growth rate of 5.

Specifically, as described above, Al_xGa_1-x
As layer 22 growth time and Al_xGa _1-xAs layer 22 '
Since the growth time was set to be the same,_xGa_1-x
Thickness h of As layer 22₀And Al_xGa_1-xAs layer 22 '
Thickness h₀′ Is considered equal (ie h₀=
h₀′). Therefore, the spatial circumference of the second periodic structure 24 is
Period d_TwoAnd the spatial period d of the first periodic structure 21.₁Difference from
(D_Two-D₁) Is Al _xGa_1-xThickness of As layer 25
h_TwoAnd Al_xGa_1-xThickness h of As layer 23₁Difference from
(H_Two-H₁) (That is, d_Two-D₁= H_Two−
h₁). Therefore, Al_xGa_1-xAs layers 23 and 25
Growth rate r_TwoIs the following equation (1)     r_Two= (H_Two-H₁) / Δt = (d_Two-D₁) / Δt ... (1 ) Is calculated by In addition, Δt is Al_xGa_1-xA
Growth time of s layer 25 and Al_xGa_1-xFormation of As layer 23
It shows the difference from a long time.

Next, the Al _x Ga _1-x As layer 2 having the mixed crystal ratio x = 0.11 as the compound semiconductor layer of the first composition 2
Find the growth rate of 2,22 '.

More specifically, the Al _x Ga _1-x As layer 23,
The growth rate r ₁ of _No. 25 is calculated by the following equation (2) r ₁ = h ₀ / t ₁ = (d ₁ −h ₁ ) / t ₁ = (d ₁ −r ₂ t ₂ ) / t ₁ (2) It is calculated. Incidentally, _{t 1} is _Al x _{Ga 1-x} As
The growth time of the layer 22, t ₂ is the Al _x Ga _1-x As layer 23.
Represents the growth time of each. This growth rate r ₁
Is also calculated by the following equation (3) r ₁ = h ₀ ′ / t ₁ = (d ₂ −h ₂ ) / t ₁ = (d ₁ −r ₂ t ₂ ′) / t ₁ (3) . Note that t ₂ ′ is Al _x Ga
The growth time of the _1-x As layer 25 is shown. When a difference occurs between the value on the right side of equation (2) and the value on the right side of equation (3) due to measurement error, it is desirable to take the average of these values.

In this case, the mixed crystal ratio x as the compound semiconductor layer of the first composition contained in the device to be manufactured
= 0.11. Growth rate r ₁ of Al _x Ga _1-x As layer, mixed crystal ratio x = as compound semiconductor layer of second composition x =
The growth rate r ₂ of the Al _x Ga _1-x As layer of 0.35 can be obtained with high accuracy. Therefore, the thickness of these layers can be accurately controlled to the target layer thickness.

Actually, based on the growth rates r ₁ and r ₂ thus obtained, A which constitutes the quantum well active layer 6 is formed.
l _x Ga _1-x As well layer (x = 0.11, layer thickness 80
Å), Al _x Ga _1-x As barrier layer (x = 0.35,
Layer thickness 50 Å), Al _x Ga _{1 -x} As guide layer (x =
The growth time was set so that 0.35, the layer thickness 300Å) was grown to the target layer thickness in each bracket. And FIG.
When the SCH-MQW laser device was manufactured by the procedure shown in (A) to FIG. 2 (D), the oscillation wavelength was 780 to 786n.
The vertical radiation angle distribution was 16 ° to 19 ° at m, and the variation could be reduced as compared with the conventional method.
As a result, the yield of the device could be increased.

(Second Example) In this example, as shown in FIG. 5A, an Al _x Ga _1-x As clad layer (x = 0.5) is formed on an n-type GaAs substrate 119 by MOCVD.
0, layer thickness 0.2 μm) 120 is formed, and then a first periodic structure 121 corresponding to the first periodic structure 21 in FIG. 3 is formed. Continuously on the same n-type GaAs substrate 119,
An Al _x Ga _1-x As clad layer (x = 0.50, layer thickness 0.2 μm) 120 ′ is formed by the MOCVD method,
Subsequently, the second periodic structure 124 corresponding to the second periodic structure 24 in FIG. 3 is formed. The first periodic structure 121 has
As shown in FIG. 5B, the first periodic structure 21 in FIG.
Exactly the same as Al as the compound semiconductor layer of the first composition
_x Ga _1-x As layer (x = 0.11, layer thickness 80Å) 12
2 and Al _x Ga as a compound semiconductor layer of the second composition
_{The 1-x} As layer (x = 0.35, layer thickness 50Å) 123 and the structure 123 are repeatedly grown eight times at constant growth times. Similarly, the second periodic structure 124 has the structure shown in FIG.
As shown in (C), Al _x G as a compound semiconductor layer of the first composition is exactly the same as the second periodic structure 24 in FIG.
a _1-x As layer (x = 0.11, layer thickness 80Å) 122 ′
And Al _x Ga _1-x as the compound semiconductor layer of the second composition
It has a structure in which an As layer (x = 0.35, layer thickness 100Å) 125 and an As layer 125 are repeatedly grown eight times at constant growth times.

Next, measurement data obtained by combining the above two periodic structures 121 and 124 is obtained by the X-ray diffraction method. After that, the second periodic structure 124 and Al _x Ga immediately below it are formed.
_1-x As clad layer (x = 0.50, layer thickness 0.2 μ
m) 120 'is etched away.

Next, the measurement data of the first periodic structure 121 left on the n-type GaAs substrate 119 is obtained by the X-ray diffraction method, and the spatial period d ₁ of the first periodic structure 121 is obtained. .

Next, the measurement data of the first periodic structure 121 is subtracted from the measurement data of the above two periodic structures to obtain the spatial period d ₂ of the second periodic structure.

Thereafter, using the above formula (1), Al _{x with} a mixed crystal ratio x = 0.35 as a compound semiconductor layer of the second composition.
The growth rate r ₂ of the Ga _1-x As layers 123 and 125 is calculated. Further, by using one or both of the above formulas (2) and (3), the Al _x Ga _1-x As layers 122, ₁ having the mixed crystal ratio x = 0.11 as the compound semiconductor layer of the first composition are formed.
The growth rate r ₁ of 22 ′ is calculated.

Actually, based on the growth rates r ₁ and r ₂ thus obtained, A which constitutes the quantum well active layer 6 is formed.
l _x Ga _1-x As well layer (x = 0.11, layer thickness 80
Å), Al _x Ga _1-x As barrier layer (x = 0.35,
Layer thickness 50 Å), Al _x Ga _{1 -x} As guide layer (x =
The growth time was set so that 0.35, the layer thickness 300Å) was grown to the target layer thickness in each bracket. And FIG.
When the SCH-MQW laser device was manufactured by the procedure shown in (A) to FIG. 2 (D), the oscillation wavelength was 780 to 786n.
The vertical radiation angle distribution was 16 ° to 19 ° at m, and the variation could be reduced as compared with the conventional method.
As a result, the yield of the device could be increased.

In this second example, the first periodic structure 121
And the second periodic structure 124 are successively formed on the same wafer 119 in this order, the two periodic structures 12
Metallographic vapor phase epitaxy (MO
The actual growth process (work) using a CVD) apparatus (or a molecular beam epitaxy (MBE) apparatus or the like) may be performed once. Therefore, the compound semiconductor layer of the first composition,
The number of steps required to obtain the growth rate of the compound semiconductor layer having the second composition can be reduced.

(Third Example) In this example, in FIG.
The quantum well active layer 6 shown is Al_xGa_1-xAs well
Layer (x = 0.11, layer thickness 80Å), Al_xGa_1-xA
s barrier layer (x = 0.36, layer thickness 50Å), Al_xGa
_1-xAs guide layer (x = 0.33, layer thickness 300Å)
To determine the growth rate of these layers
And In this example, the well layer, barrier layer, and guide layer
Are all different in composition (mixed crystal ratio x) from each other. Therefore,
The compound semiconductor layer of the first composition is formed of Al with a mixed crystal ratio x = 0.11.
_xGa_1-xAs layer and compound semiconductor layer of second composition
Al with mixed crystal ratio x = 0.36_xGa_1-xAs layer,
A compound semiconductor layer of three compositions is formed of Al with a mixed crystal ratio x = 0.33. _x
Ga_1-xThe growth layer of these three types of layers is used as the As layer.
To ask for

Specifically, as shown in FIGS. 6A and 6B, on an n-type GaAs substrate 219 as a wafer,
An Al _x Ga _1-x As clad layer (x = 0.50, layer thickness 0.2 μm) 220 is formed by the MOCVD method, and subsequently, Al _x Ga as a compound semiconductor layer of the first composition is formed.
_1-x As layer (x = 0.11, layer thickness 80Å) 222 and Al _x Ga _1-x As as a compound semiconductor layer of the second composition
The layer (x = 0.36, layer thickness 50Å) 227 and the layer 227 are repeatedly grown eight times at a constant growth time to form the first periodic structure 2
26 is formed.

Further, as shown in FIGS. 6C and 6D, the MO is formed on the n-type GaAs substrate 219 'as another wafer.
The Al _x Ga _1-x As cladding layer (x
= 0.50, layer thickness 0.2 μm) 220 ′, and subsequently Al _x Ga as a compound semiconductor layer of the first composition
_1-x As layer (x = 0.11, thickness _{80Å) Al x Ga 1-x} A of the compound semiconductor layer 222 'and the second composition
The s layer (x = 0.36, layer thickness 100Å) 228 is repeatedly grown eight times with a constant growth time to form the second periodic structure 236. It should be noted that, as can be seen from the same target layer thickness, the Al _x Ga _1-x As layer 222 is formed.
The growth time and the _Al x _{Ga 1-x} As layer 222 while the same and growth time ', as can be seen from differences in the target layer _thickness, Al _{x Ga 1-x} growth time As layer 227 and the Al _x
That is, the growth time of the Ga _1-x As layer 228 is set to be different from each other.

Further, as shown in FIGS. 6E and 6F, the MO is formed on the n-type GaAs substrate 219 ″ as another wafer.
The Al _x Ga _1-x As cladding layer (x
= 0.50, layer thickness 0.2 μm) 220 ″, and then Al _x Ga as a compound semiconductor layer of the first composition is formed.
_1-x As layer (x = 0.11, layer thickness 80Å) 222 ″ and Al _x Ga _1-x A as a compound semiconductor layer of the third composition
The s layer (x = 0.33, layer thickness 50Å) 229 and the s layer 229 are repeatedly grown eight times with a constant growth time to form the third periodic structure 246. It should be noted here that, as can be seen from the same target layer thickness, the Al _x Ga _1-x As layers 222,
222 ′ growth time and Al _x Ga _1-x As layer 222 ″
That is, the growth time is set to be the same.

Next, the spatial period _{d 1} of the first periodic structure 226 by X-ray diffraction method, the spatial period _{d 2} of the second periodic structure 236, spatial period _{d 3} of the first periodic structure 246
Are measured respectively.

Next, using the above formula (1), Al having a mixed crystal ratio x = 0.36 as the compound semiconductor layer of the second composition is used.
The growth rate r ₂ of the _x Ga _1-x As layers 227 and 228 is calculated. Further, by using one or both of the above formulas (2) and (3), the Al _x Ga _1-x As layer 222 having a mixed crystal ratio x = 0.11 as the compound semiconductor layer of the first composition is 222.
The growth rate r ₁ of 222 ′ is calculated. This growth rate r ₁ is also the growth rate of the Al _x Ga _{1- x} As layer 222 ″.

Further, as the compound semiconductor layer of the third composition
Al with mixed crystal ratio x = 0.33_xGa_{1 -X}As layer 229
Growth rate r_ThreeBy the following equation (4)     r_Three= H_Three/ T_Three= (D_Three-H₀″) / T_Three= (D_Three-H₀) / T_Three        = (D₁-R₁t₁) / T_Three                                … (4 ) Calculate by Note that t₁Is Al_xGa_1-xAs
Growth time of layer 222, t _ThreeIs Al_xGa_1-xAs layer 2
Each of the 29 growth times is represented.

Thus, the three types of layers, that is, the mixed crystal ratios are x = 0.11, x = 0.36, and x = 0.33, respectively.
The growth rate of the Al _x Ga _1-x As layer can be accurately obtained.

There are four compound semiconductor layers whose growth time is to be determined.
In the case of the type, further, the compound semiconductor layer of the first composition and the compound semiconductor layer of the fourth composition are repeatedly grown a plurality of times at constant growth times to form a fourth periodic structure, and X-ray diffraction is performed. The spatial period of the fourth periodic structure is also measured by the method. Then, the growth rate of the compound semiconductor layer having the fourth composition may be obtained by using the same formula as the above formula (4).

As described above, when there are n kinds of compound semiconductor layers (n is a natural number of 3 or more) whose growth time is to be determined,
There are formed n types of periodic structures, that is, the number of types of compound semiconductor layers for which the growth time is to be determined, by forming two different types of compound semiconductor layers, which are different from each other, repeatedly a plurality of times with constant growth times. Then, the growth rate of the compound semiconductor layer having the n-th composition may be sequentially obtained. Note that when one of the two types of compound semiconductor layers is always the compound semiconductor layer of the first composition when forming each periodic structure, the third type semiconductor layer has a third composition semiconductor layer as compared with the case of randomly extracting the two types of compound semiconductor layers.
When calculating the growth rate of the compound semiconductor layer after the composition, it is possible to exclude the entry of measurement error. Therefore,
The growth rate of the compound semiconductor layer having the third composition or later can be accurately obtained. As a result, when a compound semiconductor device including n types of compound semiconductor layers is manufactured, the thickness of each compound semiconductor layer can be accurately controlled to the target layer thickness.

In this embodiment, the case where the compound semiconductor layer whose growth time is to be determined is AlGaAs, that is, a ternary material is described, but the present invention is not limited to this. The present invention can be suitably applied to various materials such as quaternary materials such as InGaAlP used for red lasers.

[0058]

As is apparent from the above, according to the compound semiconductor device manufacturing method of the present invention, the compound semiconductor layer of the above-mentioned compound semiconductor layer is grown so that the compound semiconductor layer contained in the device to be manufactured has a target layer thickness. The growth time can be accurately determined. Therefore, the thickness of the compound semiconductor layer can be accurately controlled to the target layer thickness.

Further, according to the semiconductor laser device of the present invention, it is possible to reduce variations in radiation characteristics, particularly variations in vertical radiation angle, as compared with the prior art. As a result, the yield of the device can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing steps of a general compound semiconductor device manufacturing method.

FIG. 2 is a diagram showing steps of a general compound semiconductor device manufacturing method.

FIG. 3 is a diagram illustrating a sectional structure of a growth rate monitor wafer manufactured by the compound semiconductor device manufacturing method according to the embodiment of the present invention.

FIG. 4 is a diagram showing a result (waveform) of a spatial period of a periodic structure formed by repeatedly growing two kinds of compound semiconductor layers a plurality of times at a constant period by an X-ray diffraction method.

FIG. 5 is a diagram illustrating a cross-sectional structure of a growth rate monitor wafer manufactured by the compound semiconductor device manufacturing method according to the embodiment of the present invention.

FIG. 6 is a diagram illustrating a cross-sectional structure of a growth rate monitor wafer manufactured by the compound semiconductor device manufacturing method according to the embodiment of the present invention.

[Explanation of symbols]

19, 19 ', 119, 219, 219', 219 "
n-type GaAs substrate 21,121,226 First periodic structure 24,124,236 Second periodic structure 246 Third periodic structure 22, 22 ', 122, 122', 222, 222 ',
222 ″ Mixed crystal ratio x as a compound semiconductor layer of the first composition x
= 0.11 Al_xGa_1-xAs layer 23,25,123,125 Second composition compound semiconductor
Al with a mixed crystal ratio x = 0.35 as a layer_xGa_1-xAs
layer 227 and 228 are mixed as the compound semiconductor layer of the second composition.
Al with a crystal ratio x = 0.36_xGa_1-xAs layer 229 Mixed crystal ratio as compound semiconductor layer of third composition x =
0.33 Al_xGa _1-xAs layer

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2G001 AA01 BA18 CA01 GA01 GA13                       KA11 LA11 MA05                 5F045 AA04 AB17 AF04 BB01 CA12                       GB11 GB19                 5F073 AA09 AA22 AA45 AA74 BA04                       CA05 CB02 DA05 DA24 EA03                       EA19 HA10 HA12

Claims (6)

[Claims] 1. A compound semiconductor device manufacturing method for producing a device including compound semiconductor layers of a first composition and a second composition which are different in composition and are to be grown to a target layer thickness by a predetermined growth method. The step of determining a growth time for each compound semiconductor layer is performed by repeatedly growing a compound semiconductor layer having a first composition and a compound semiconductor layer having a second composition on a wafer a plurality of times at constant growth times. Forming a periodic structure of the compound semiconductor layer of the first composition on the wafer, the same growth time as the growth time of the compound semiconductor layer of the first composition of the first periodic structure, and the compound semiconductor layer of the second composition. And a step of forming a second periodic structure by repeatedly growing a plurality of times with a growth time different from the growth time of the compound semiconductor layer of the second composition having the first periodic structure, and the second periodic structure by an X-ray diffraction method. Measuring the spatial period of the periodic structure and the spatial period of the second periodic structure, and the difference between the measured spatial period of the first periodic structure and the spatial period of the second periodic structure. And a step of determining a growth rate of the compound semiconductor layer having the second composition and a growth rate of the compound semiconductor layer having the first composition. 2. The compound semiconductor device manufacturing method according to claim 1, wherein the difference between the measured spatial period of the first periodic structure and the measured spatial period of the second periodic structure is the first period. The second composition is divided by the difference between the growth time of the compound semiconductor layer of the second composition when the structure is formed and the growth time of the compound semiconductor layer of the second composition when the second periodic structure is formed. Of the growth rate of the compound semiconductor layer, the measured spatial period of the first periodic structure or the spatial period of the second periodic structure, and the growth rate of the compound semiconductor layer of the second composition in the periodic structure. A method of manufacturing a compound semiconductor device, wherein the growth rate of the compound semiconductor layer of the first composition is obtained based on the difference from the thickness of the compound semiconductor layer of the second composition calculated from 3. The compound semiconductor device manufacturing method according to claim 1, wherein the first periodic structure and the second periodic structure are successively formed on the same wafer in this order, and are formed by an X-ray diffraction method. After obtaining the measurement data that combines the two periodic structures and etching and removing the second periodic structure, the measurement data of the first periodic structure left on the wafer is obtained by the X-ray diffraction method. Then, the spatial period of the first periodic structure is obtained, and the measurement data of the first periodic structure is subtracted from the measurement data of the two periodic structures to obtain the second periodic structure.
A method for manufacturing a compound semiconductor device, characterized in that the spatial period of the periodic structure of is determined. 4. The method of manufacturing a compound semiconductor device according to claim 1, wherein when there are n kinds of compound semiconductor layers whose growth times are to be determined, two different kinds of compound semiconductor layers in each of them have a constant growth time. 2. A method for manufacturing a compound semiconductor device, comprising forming n kinds of periodic structures each of which is repeatedly grown a plurality of times. 5. The compound semiconductor device manufacturing method according to claim 1, wherein the compound semiconductor layer of the first composition contained in the first and second periodic structures has an Al _x Ga thickness of 70Å to 100Å.
_1-x As (where x = 0.11), and the compound semiconductor layer of the second composition contained in the first periodic structure has a thickness of 50Å to 60Å Al _x Ga _1-x. As
(However, x = 0.35.), And the compound semiconductor layer of the second composition included in the second periodic structure has a thickness of 90Å to 110Å Al _x Ga _1-x A.
A compound semiconductor device manufacturing method, wherein s (where x = 0.35). 6. A semiconductor laser device manufactured by the compound semiconductor device manufacturing method according to claim 1, wherein the semiconductor laser device has a separate confinement hetero structure and a multiple quantum well structure, and is made of an AlGaAs material. Negative oscillation wavelength 780nm to 7
A semiconductor laser device having a range of 86 nm.