JP3316083B2 - GaAs single crystal substrate for liquid phase epitaxial growth and liquid phase epitaxial growth method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a Ga _1-X Al _X As (where, 0 ≦ X <1) the liquid with the epitaxial growth layer used to form a liquid phase epitaxial growth method GaAs single crystal substrate and the substrate The present invention relates to a phase epitaxial growth method.

[0002]

BACKGROUND OF THE INVENTION GaAs having a {100} plane as a main surface
s single crystal substrate [hereinafter referred to as {100} GaAs substrate or Ga
It is called As substrate. ], Ga _1-x Al _x As (provided that
0 ≦ X <1) In a liquid phase epitaxial growth method, which is one method of forming an epitaxial growth layer, a GaAs crystal or a GaAs crystal and Al are dissolved in a Ga melt at a predetermined temperature (for example, 900 ° C.) until the GaAs crystal and Al become supersaturated. A supersaturated Ga solution (hereinafter referred to as a liquid phase growth Ga solution or a growth Ga solution)
It is called a solution. ) Is brought into contact with the main surface of the GaAs substrate heated to the same temperature, and then a predetermined temperature (for example, 75
In this method, Ga _1-x Al _x As (where 0 ≦ X <1) is deposited and grown on the GaAs substrate by gradually lowering the temperature to 0 ° C.).

Conventionally, as a standard of the plane orientation, a {100} GaAs substrate which allows a plane orientation error (θ) of up to 0.5 ° is used, and Ga _{1− is} formed on the main surface of the substrate by the liquid phase epitaxial growth method. _X Al _X As (where 0 ≦ X <1)
An epitaxial growth layer (hereinafter referred to as a Ga _1-x Al _x As layer) was formed.

[0004]

However, within the tolerance of the plane orientation error, a {100} GaAs substrate having a plane orientation error (θ) of more than 0.2 ° is used, and a liquid phase epitaxial growth method is used on the substrate. When the Ga _1-x Al _x As layer is grown and formed by the method, a growth step reaching 1 μm is formed on the surface of the Ga _1-x Al _x As layer, and the surface morphology is deteriorated. This was a major cause of lower yield.

Accordingly, the present invention provides an optimum {100} GaAs substrate and a liquid phase epitaxial growth method using the substrate in order to form a Ga _1-x Al _x As layer having a good surface morphology by a liquid phase epitaxial growth method. The purpose is to provide.

[0006]

SUMMARY OF THE INVENTION The inventor of the present invention provides Ga
The surface morphology of the _1-X Al _X As layer is {100} G
The present inventors have found that it largely depends on the plane orientation error of the aAs substrate, and as a result of earnest research, have reached the present invention. The present invention relates to Ga
On a As substrate, Ga _1-x Al _x As (where 0 ≦ X <
1) A GaAs single crystal substrate used for forming a layer by a liquid phase epitaxial growth method, wherein the GaAs
The present invention is characterized in that the crystal plane orientation of the s substrate surface is a {100} plane with a plane orientation error of 0.2 ° or less, thereby obtaining the Ga _1-x Al _x As layer having a good surface morphology. Solved the problem. The method of the present invention relates to a liquid phase epitaxial growth method using the GaAs substrate. In the production of a {100} GaAs single crystal substrate having a plane orientation error of 0.2 ° or less, the plane orientation error (θ) frequently obtained is 0.1 ° <θ ≦ 0.2 °.
{100} GaAs single crystal substrate, which is preferably used in manufacturing.

[0007]

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

Incidentally, the notation method of the crystal plane orientation is described in H.I. C. Gatos et al. (Journ
al of Electrochemical Soc
iety, vol. 107, no. 5 (1960),
P. 427-436). Also, $ 10
As the 0 ° plane,

[0009]

(Equation 1)

There are six types of planes, which are crystallographically equivalent. Therefore, in this embodiment, the (100) plane is used as a representative example.

(Examples 1 and 2 and Comparative Examples 1 and 2) Zn-doped (impurity concentration 1-5 ×) manufactured by boat clone method
10 ¹⁹ / cm ³ ) A p-type GaAs single crystal having a main surface with crystal plane orientation errors of 0.1 ° (Example 1), 0.2 ° (Example 2), and 0.3 ° (Comparative Example 1) ) And 0.5 ° (Comparative Example 2), and then sliced so as to have a (100) plane.
A mirror-polished wafer having the above-mentioned crystal plane orientation of 0 μm was obtained, and these were GaAs for growing a Ga _1-x Al _x As layer.
An s substrate was used.

FIG. 1 is a sectional view showing one structure of an epitaxial wafer obtained by the method of the present invention. The epitaxial wafer shown in FIG. 1 is a p-type (100) GaAs
On a s substrate 10, a 150 μm thick p-type Ga _0.25 Al
_0.75 As clad layer 11, 1 μm thick p-type Ga _0.62 A
l _0.38 As active layer 12 and 50 μm thick n-type Ga _0.25
The structure is such that each layer of the Al _0.75 As clad layer 13 is sequentially formed.

The above-mentioned plane orientation errors of 0.1 °, 0.2 °,
0.3 ° and 0.5 ° with (100) plane as main surface 4
Using various kinds of GaAs substrates as substrates for liquid phase epitaxial growth, epitaxial wafers having the structure shown in FIG. 1 were manufactured by the slide boat method shown in FIG. FIG.
In the above, the GaAs substrate 10 is fixed on the upper surface of the boat body 20. A slide-type solution reservoir 21 (hereinafter, referred to as a solution reservoir 21) that slides on the boat body 20 includes:
Ga solution for p-type Ga _0.25 Al _0.75 As cladding layer growth 2
First solution reservoir 22 containing 2a, p-type Ga _0.62 Al _0.38
A second solution reservoir 23 containing a Ga solution 23a for growing an As active layer and a third solution reservoir 24 containing a Ga solution 24a for growing an n-type Ga _0.25 Al _0.75 As clad layer are provided. There is no bottom and each Ga solution for growth comes into direct contact with the boat body 20. The p-type dopant and the n-type dopant are Zn and Te, respectively, and the dopant is added to the growth Ga solution together with the GaAs crystal and Al.

Next, using the above device, the p-type (10
0) The step of forming the three epitaxial growth layers on the GaAs substrate 10 will be described. First, the solution reservoir 21 is slid in the direction of the arrow from the position of FIG.
Is set on the GaAs substrate 10, for example, at 900 ° C.
P-type Ga _0.25 Al _0.75 As while cooling down to 800 ° C
A cladding layer 11 is grown on the GaAs substrate 10 (FIG. 2B). Next, the solution reservoir 21 is further slid in the direction of the arrow, and the growth Ga solution 23a in the second solution reservoir 23 is set on the GaAs substrate.
The p-type Ga _0.62 Al _0.38 As active layer 12 is grown on the p-type Ga _0.25 Al _0.75 As clad layer 11 while the temperature is lowered to 95 ° C. (FIG. 2C). Next, the solution reservoir 21 is further slid in the direction of the arrow, the growth Ga solution 24a in the third solution reservoir 24 is set on the GaAs substrate, and the temperature is reduced, for example, from 795 ° C. to 650 ° C. while n-type Ga _0.25
The Al _0.75 As clad layer 13 is made of the p-type Ga _0.62 Al
_It is grown on the _0.38 As active layer 12 (FIG. 2D). Thereafter, the solution reservoir 21 is further slid in the direction of the arrow to complete the liquid phase epitaxial growth step [FIG. 2 (e)].
An epitaxial wafer having the structure shown in FIG. 1 was obtained.

FIG. 3 shows plane orientation errors of 0.1 °, 0.2 °,
The surface morphology and surface roughness of the epitaxial wafer surface (the surface of the n-type Ga _0.25 Al _0.75 As clad layer 13) obtained by the above method using the (100) GaAs substrate of 0.3 ° and 0.5 ° as the substrate for epitaxial growth. [FIG. 3A: plane orientation error 0.1 °, FIG.
(B): plane orientation error 0.2 °, FIG. 3 (c): plane orientation error 0.3 °, FIG. 3 (d): plane orientation error 0.5 °].

The surface roughness is determined by Kosaka La.
surface roughness meter (Model
TR 100X).

FIG. 3 shows that the morphology of the n-type Ga _0.25 Al _0.75 As cladding layer surface (epitaxial layer surface) greatly depends on the plane orientation error of the (100) GaAs substrate. A near flat growth surface can be obtained, but it is found that when the angle is 0.3 °, a fine growth step starts to appear on the growth surface, and when the angle is 0.5 °, the growth step becomes large and the surface roughness becomes about 1 μm. I do.

The inventors further set the angle of the plane orientation error (θ) in the range of 0.1 ° to 0.2 °.
A (100) GaAs substrate of 0.12 °, 0.14 °, 0.16 °, 0.18 ° is used as a substrate for epitaxial growth, and an epitaxial wafer having the same structure as in FIG. Created after. In the case of using a (100) GaAs substrate having any plane orientation error, the mirror surface equivalent to the results obtained with the (100) GaAs substrate having the plane orientation errors of 0.1 ° and 0.2 ° obtained in FIG. It has been found that a flat growth surface close to the above can be obtained.

Therefore, in order to form a Ga _1-x Al _x As layer having a good surface morphology on a {100} GaAs substrate by a liquid phase epitaxial growth method, the above-mentioned {1}
It is important that the plane orientation error of the 00｝ GaAs substrate be 0.2 ° or less.

(Embodiments 3 and 4) Si-doped (impurity concentration 1-2 × 10 ¹⁸ / c) manufactured by boat-grown method
m ³ ) n-type GaAs single crystal was processed in the same manner as in Example 1 and Example 2, and the plane orientation error was 0.1 ° (Example 3).
Then, a (100) GaAs substrate of 0.2 ° (Example 4) was obtained, and a GaAs growth layer was formed on the GaAs substrate by a liquid phase epitaxial growth method.

FIG. 4 is a sectional view showing one structure of the epitaxial wafer according to the third and fourth embodiments. The epitaxial wafer shown in FIG. 4 has an n-type (100) GaAs substrate 30 and an n-type (Si-doped) GaAs having a thickness of 80 μm.
s layer 31 and p-type (Si-doped) GaAs having a thickness of 60 μm
The structure is such that the s layer 32 is sequentially formed.

FIG. 5 shows an epitaxial wafer having the above structure.
Was manufactured by the slide boat method shown in FIG. In FIG. 5, the n-type GaAs substrate 30 is fixed on the upper surface of the boat body 40. The n-type and p-type GaAs growth Ga are stored in the slide type solution reservoir 41 that slides on the boat body 40.
Solution (Ga solution to which GaAs crystal and Si are added) 42
A solution reservoir 42 for accommodating a is provided. The solution reservoir 42 has no bottom and the Ga solution for growth directly contacts the boat body 40.

Next, a process of forming an epitaxial growth layer on the n-type (100) GaAs substrate 30 using the slide boat in the above state will be described. First, the slide-type solution reservoir 41 is slid in the direction of the arrow from the position of FIG. 5A using the operation rod 45, and the growth Ga solution 42a in the solution reservoir 42 is set on the GaAs substrate 30. The temperature at this time was 980 ° C., and FIG. 5 (b)]. After maintaining at this temperature for 10 minutes, the n-type G
The aGaAs layer 31 and the p-type GaAs layer 32 are
Grow on zero. Next, the slide solution reservoir 41 is further slid in the direction of the arrow to complete the liquid phase epitaxial growth step (FIG. 5C), and obtain epitaxial wafers according to Examples 3 and 4 having the structure shown in FIG. Was.

When the surface morphology and surface roughness of the epitaxial layer 32 obtained by the above method were evaluated by the same method as in Examples 1 and 2, the same results as in Examples 1 and 2 were obtained. Was. That is, plane orientation error 0.2
It has been found that, when a GaAs layer is grown on a {100} GaAs substrate of less than 100 ° C. by an epitaxial growth method, the surface morphology of the GaAs growth layer becomes extremely good.

[0025]

As described above, according to the present invention, a Ga _1-x Al _x As layer (0 ≦ X <1) having a good surface morphology can be formed by a liquid phase epitaxial growth method.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one structure of an epitaxial wafer obtained by a method of the present invention.

FIG. 2 is a process chart of a slide boat method in Examples 1 and 2 and Comparative Examples 1 and 2.

FIG. 3 is a drawing including photographs showing the surface morphology and surface roughness of the epitaxial wafer surface obtained in Examples 1 and 2 and Comparative Examples 1 and 2.

FIG. 4 is a cross-sectional view showing one structure of an epitaxial wafer obtained in Examples 3 and 4.

FIG. 5 is a process chart of a slide boat method in Examples 3 and 4.

[Description of Signs] 10 p-type (100) GaAs single crystal substrate 11 p-type Ga _0.25 Al _0.75 As clad layer 12 p-type Ga _0.62 Al _0.38 As active layer 13 n-type Ga _0.25 Al _0.75 As clad layer 20 boat body 21 slide Type solution reservoir 22 first solution reservoir 22a p-type Ga _0.25 Al _0.75 As cladding layer growth G
a solution 23 second solution reservoir 23a p-type Ga _0.62 Al _0.38 Ga solution for growing As active layer 24 third solution reservoir 24an n-type Ga _0.25 Al _0.75 As cladding layer growing G
a solution 25 operation rod 30 n-type (100) GaAs single crystal substrate 31 n-type (Si-doped) GaAs layer 32 p-type (Si-doped) GaAs layer 40 boat body 41 sliding solution reservoir 42 solution reservoir 42 a Ga solution for growth 45 Operation stick

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Masato Yamada 2-13-1, Isobe, Annaka-shi, Gunma Shin-Etsu Semiconductor Co., Ltd. Isobe Plant (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 21/02 H01L 21/20

Claims (4)

(57) [Claims] 1. The method according to claim 1, wherein Ga _{1 -x} Al _{x is formed} on a GaAs single crystal substrate.
As (provided that 0 ≦ X <1) a GaAs single crystal substrate used for forming an epitaxial growth layer by a liquid phase epitaxial growth method, wherein the crystal plane orientation of the GaAs single crystal substrate surface has a plane orientation error (θ) of θ ≦ θ. A GaAs single crystal substrate for liquid phase epitaxial growth, characterized by a {100} plane of 0.2 °. 2. The method according to claim 1, wherein Ga _1-x Al _{x is formed} on a GaAs single crystal substrate.
As (however, 0 ≦ X <1) a GaAs single crystal substrate used for forming an epitaxial growth layer by a liquid phase epitaxial growth method, wherein the GaAs single crystal substrate has a crystal plane having a plane orientation error (θ) of 0. 1 ° <θ ≦
A GaAs single crystal substrate for liquid phase epitaxial growth, characterized by having a {100} plane in a range of 0.2 °. 3. A liquid phase epitaxial growth method comprising forming a Ga _1-x A1 _x As (0 ≦ X <1) epitaxial growth layer on the GaAs single crystal substrate according to claim 1. 4. A liquid phase epitaxial growth method comprising forming a Ga _1-x A1 _x As (0 ≦ X <1) epitaxial growth layer on the GaAs single crystal substrate according to claim 2.