JP3194327B2 - Metalorganic vapor phase epitaxy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal organic chemical vapor deposition (MOCVD) method based on a selective growth technique on a (111) B surface of a GaAs substrate. In addition, (1
11) Plane B means a state in which the outermost surface of the GaAs substrate is composed of an As atomic layer.

[0002]

2. Description of the Related Art For example, a method of forming an AlGaAs-based compound semiconductor layer on a GaAs substrate by the MOCVD method has been proposed by G.
Since it is possible to uniformly form a large-area ultra-thin film on an aAs substrate, it has attracted attention in recent years and has been used for mass production of semiconductor lasers and high-mobility transistors. On the other hand, a technique for selectively growing a GaAs-based compound semiconductor layer on the (111) B plane of a GaAs substrate has been developed (for example, see the literature, S. And
o, et al., "Selectiveepitaxy of GaAs / AlGaAs on (11
1) B substrates by MOCVD and applications tonanomet
er structures ", Journal of Crystal Growth 115 (199
1), pp. 69-73).

In this selective growth technique, first, FIG.
As shown in FIG. 1A, a SiO ₂ substrate having a thickness of about 0.1 μm is formed on a (111) B surface of a GaAs substrate 10.
Alternatively, an insulating film 12 made of SiN is deposited by a CVD method or the like. Next, as shown in FIG. 1B, the insulating film 12 is removed in the form of stripes using ordinary photolithography and etching techniques, and the (111) B of the substrate 10 is removed.
Expose the surface. The exposed portion of the substrate is hereinafter referred to as
It is called a window (window) 14. The width direction of the window 14 matches the [0,1, -1] direction of the GaAs substrate 10,
The longitudinal direction of the window 14 corresponds to [2,
The insulating film 12 is removed in a stripe shape so as to match the [-1, -1] direction. 1 and 2 are partially cutaway views of the substrate.

When a compound semiconductor layer 20 made of GaAs is grown on such a window 14 by MOCVD, as shown in FIG.
A compound semiconductor layer 20 having a 10 ° plane and having a (111) plane in a direction perpendicular to the substrate is crystal-grown. And FIG.
As shown in FIG. 1A, the compound semiconductor layer 20 grows only on the window 14, and the compound semiconductor layer 20 does not grow on the insulating film 12. Such growth of the compound semiconductor layer 20 exclusively in the film thickness direction is called growth of the compound semiconductor crystal layer in the direction perpendicular to the substrate or vertical growth mode. On the other hand, when the crystal growth conditions in the MOCVD method are changed, not only the compound semiconductor layer 20 grows in the thickness direction, but also the compound semiconductor layer 20 is formed on the insulating film 12 as shown in FIG. The compound semiconductor layer 20 grows so as to protrude on the insulating film 12. Such growth of the compound semiconductor layer is called growth of the compound semiconductor crystal layer in the horizontal direction of the substrate or horizontal growth mode.

In the prior art, a GaAs-based compound semiconductor layer is grown by MOCVD to form a crystal.
a Using trimethylgallium (TMG) as a raw material,
Arsine (AsH ₃ ) is used as a raw material. MOCV
In order to obtain the vertical growth mode in the method D, usually, the substrate 10 is heated to about 800 ° C. and TMG is increased to about 2.3 ×
10 ^-6 atm, arsine about 3 × 10 ^-5 atm (arsine /
TMG gas partial pressure ratio = about 13). As the heating temperature of the substrate 10 is lowered and the partial pressure ratio of arsine / TMG gas is increased, a horizontal growth mode is recognized. For example, when the heating temperature of the substrate 10 is about 600 ° C., TMG is about 2.3 × 10 ⁻⁶ atm, and arsine is about 2 × 10 ⁻⁴ atm (arsine / TMG gas partial pressure ratio = about 87), The crystal growth rate in the horizontal direction is about 23 times the crystal growth rate in the vertical direction of the substrate, and a substantially horizontal growth mode can be achieved. The horizontal direction of the substrate means a direction parallel to the surface of the substrate 10, and the vertical direction of the substrate means a direction perpendicular to the surface of the substrate 10.

[0006]

However, such conventional control of the horizontal growth mode or the vertical growth mode requires a change in the substrate heating temperature of about 200 ° C. and a change in the supply amount of arsine of about 7 times. I do. It takes a long time to change the substrate heating temperature, during which time the crystal growth of the compound semiconductor crystal layer must be interrupted. However, such interruption of crystal growth causes contamination on the surface of the compound semiconductor layer, resulting in defects on the surface of the compound semiconductor layer and abnormally high carrier concentration. Therefore, interruption of crystal growth for a long time must be avoided.
Further, even if the compound semiconductor layer is grown while the substrate is heated to about 600 ° C., a high-quality compound semiconductor layer cannot be obtained.

Accordingly, it is an object of the present invention to provide a method of forming a compound semiconductor crystal layer in a substrate horizontal direction or a substrate vertical direction without changing a substrate heating temperature (or changing the temperature within a small temperature range). An object of the present invention is to provide a MOCVD method based on a selective growth technique capable of arbitrarily controlling the growth.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is to provide a GaAs substrate.
A compound semiconductor crystal layer having a {110} plane in the horizontal direction of the substrate and a (111) plane in the vertical direction of the substrate and containing at least a Ga element and an As element on the (111) B plane of the substrate made of In the metal organic chemical vapor deposition method for growing, in the growth of the compound semiconductor crystal layer in the vertical direction of the substrate, triethyl gallium is used as a Ga source gas, and in the growth of the compound semiconductor crystal layer in the horizontal direction of the substrate, The metal organic chemical vapor deposition method according to the present invention, wherein trimethyl gallium is used as a Ga source gas, trimethyl arsenic is used as an As source gas, and a partial pressure ratio of As source gas / Ga source gas is 100 or more. (M
OCVD).

In the MOCVD method of the present invention, in some cases, in growing the compound semiconductor crystal layer in the horizontal direction of the substrate, trimethylgallium is used as a Ga source gas, and trimethylarsenic and arsine are used as an As source gas. can do. In growing the compound semiconductor crystal layer in the direction perpendicular to the substrate, triethylgallium can be used as a Ga source gas, and arsine can be used as an As source gas.

The substrate heating temperature in growing the compound semiconductor crystal layer in the direction perpendicular to the substrate is 650 ° C. to 850 ° C.
It is desirable that If the substrate heating temperature is lower than 650 ° C., the crystallinity of the compound semiconductor layer decreases, and a high-quality compound semiconductor layer cannot be formed. On the other hand, when the temperature exceeds 850 ° C., evaporation of As atoms increases, and the surface of the compound semiconductor layer becomes rough.

The compound semiconductor crystal layer may contain an Al element.

[0012]

According to the MOCVD method of the present invention, the growth of the compound semiconductor crystal layer in the substrate vertical direction and the substrate horizontal direction
a The composition of the source gas and the As source gas is changed.
It can be arbitrarily controlled by controlling the partial pressure ratio of the s source gas / Ga source gas.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on embodiments with reference to the drawings.

(Embodiment 1) In Embodiment 1, the dependence on the source gas of the vertical growth mode and the horizontal growth mode and As
The dependence of the mixing ratio of source gas / Ga source gas was examined. Ga
The following combinations were used as source gas and As source gas. Note that TEG is an abbreviation for triethylgallium, TMG is an abbreviation for trimethylgallium, and TMAs is an abbreviation for trimethylarsenic.

First, as shown in FIG.
0.1 μm on the (111) B surface of the substrate 10 made of
An insulating film 12 made of SiO ₂ or SiN having a thickness of about 30 nm is deposited by a CVD method or the like. Next, as shown in FIG. 1B, the insulating film 12 is removed in a stripe shape by using a normal photolithography technique and an etching technique.
The window 14 is formed by exposing the (111) B surface of the aAs substrate 10. The width of the window 14 was 5 μm. Insulation is performed so that the width direction of the window 14 matches the [0,1, -1] direction of the GaAs substrate 10 and the longitudinal direction of the window 14 matches the [2, -1, -1] direction of the GaAs substrate 10. The film 12 is removed in a stripe shape.

When a compound semiconductor layer 20 made of GaAs is crystal-grown on the window 14 by the MOCVD method, as shown in FIG. 2A or FIG. A compound semiconductor layer 20 made of GaAs having a 110 ° plane and having a (111) plane in a direction perpendicular to the substrate grows.

In Example 1, the supply amount of the Ga source gas was kept constant at 3 × 10 ⁻⁶ atm as the pressure in the MOCVD reactor. When the pressure ratio of As source gas / Ga source gas (hereinafter referred to as source gas partial pressure ratio) in the MOCVD reactor is changed, the growth state of the compound semiconductor layer in the vertical growth mode and the horizontal growth mode, specifically, ,
The crystal growth rate of the compound semiconductor layer in the vertical direction of the substrate and the crystal growth rate in the horizontal direction of the substrate were examined. The result is shown in FIG. The substrate heating temperature was 750 ° C., and the crystal growth time was 30 minutes.

In FIG. 3, the crystal growth rate in the direction perpendicular to the substrate is:
This is a value obtained by dividing the thickness of the compound semiconductor layer 20 made of GaAs formed on the window 14 (indicated by “V” in FIG. 2B) by a unit time. The crystal growth rate in the horizontal direction of the substrate is the same as that of GaAs formed on the insulating film 12.
Of the compound semiconductor layer 20 (indicated by “H” in FIG. 2B) divided by a unit time.

As is apparent from FIG. 3, in the combination of (TEG + arsine), the vertical growth mode is recognized without depending on the source gas partial pressure ratio. However, the horizontal growth mode was not recognized until the raw material gas partial pressure ratio reached 200. Therefore, by using the combination of (TEG + arsine), the vertical growth mode can be exclusively obtained up to a source gas partial pressure ratio of about 300.

In the combination of (TMG + TMAs) or the combination of (TMG + arsine), when the source gas partial pressure ratio is small, the crystal growth of the compound semiconductor layer 20 is mainly in the vertical growth mode. As the source gas partial pressure ratio increased, the horizontal growth mode was developed. Moreover, as the source gas partial pressure ratio increased, the crystal growth rate in the horizontal direction of the substrate increased, and the crystal growth rate in the vertical direction of the substrate tended to decrease. Note that this tendency was more strongly recognized when TMAs was used as the As source gas than Arsine.

(Embodiment 2) In Embodiment 2, a compound semiconductor layer 2 made of GaAs is formed in the same manner as in Embodiment 1.
0 on window 14, MOC based on selective growth technology
It is grown by the VD method. In Example 2, the vertical growth mode and the horizontal growth mode when the source gas partial pressure ratio was fixed at 53 and the substrate heating temperature was changed were examined. FIG. 4 shows the results. It should be noted that the supply amount of the Ga source gas is M
The pressure in the OCVD reactor was kept constant at 3 × 10 ⁻⁶ atm. The crystal growth time was 30 minutes.

In the combination of (TMG + TMAs) or (TMG + arsine), when the substrate heating temperature was 800 ° C., only the vertical growth mode was recognized, and the horizontal growth mode was not recognized. As the substrate heating temperature was lowered, a horizontal growth mode appeared. In addition, it was found that the lower the substrate heating temperature, the higher the crystal growth rate in the horizontal direction of the substrate and the lower the crystal growth rate in the vertical direction of the substrate. Note that this tendency was more strongly recognized when TMAs was used as the As source gas than Arsine.

In the combination of (TEG + arsine), when the substrate heating temperature was 750 ° C., only the vertical growth mode was recognized.

From the results of Example 1 and Example 2 above,
In the MOCVD method based on the selective growth technique, by adopting the following method, it is possible to change the substrate heating temperature without changing it (or even if it is changed, it can be changed within a small range).
The growth of the compound semiconductor crystal layer in the substrate horizontal direction or the substrate vertical direction can be arbitrarily controlled. (A) In growing a compound semiconductor crystal in the direction perpendicular to the substrate, a source gas containing triethylgallium (TEG) is used. (B) In growing the compound semiconductor crystal in the horizontal direction of the substrate, a source gas containing trimethylgallium (TMG) and trimethylarsenic (TMAs) is used, and the gas partial pressure ratio of trimethylarsenic / trimethylgallium is set to 100 or more.

In some cases, (B ′) in growing the compound semiconductor crystal layer in the horizontal direction of the substrate, trimethylgallium is used as a Ga source gas, and trimethylarsenic and arsine are used as an As source gas.

The substrate heating temperature in growing the compound semiconductor crystal layer in the direction perpendicular to the substrate is 650 ° C. to 85 ° C.
It is desirable that 0 ゜ C. The substrate heating temperature in growing the compound semiconductor crystal layer in the horizontal direction of the substrate is preferably as low as possible (eg, about 650 ° C.) as long as the crystallinity of the grown compound semiconductor layer is not deteriorated.

Example 3 In Example 3, a light emitting device comprising a semiconductor laser was manufactured based on the MOCVD method of the present invention described above. Hereinafter, a method for manufacturing a semiconductor laser will be described with reference to FIGS. 1 and 5, and the supply amount of the source gas is represented by the partial pressure in the MOCVD reactor. The total pressure in the MOCVD reactor was 0.09 atm.

[Step-300] (Preparation of Substrate) First, an insulating film 12 made of SiO ₂ or SiN having a thickness of about 0.1 μm is formed on the (111) B face of the substrate 10 made of GaAs by CVD or the like. (See FIG. 1A). Next, the window 14 is formed by removing the insulating film 12 in a stripe shape using a normal photolithography technique and an etching technique, exposing the (111) B surface of the GaAs substrate 10. The width of the window 14 was 5 μm. The width direction of the window 14 coincides with the [0,1, -1] direction of the GaAs substrate 10, and the window 14
The insulating film 12 is removed in a stripe shape so that the longitudinal direction of the insulating film 12 coincides with the [2, -1, -1] direction of the GaAs substrate 10 (see FIG. 1B).

[Step-310] (Formation of Buffer Layer 30) Next, n is formed on the window 14 of the substrate 10 under the following conditions.
A buffer layer 30 made of GaAs and having a thickness of 0.2 μm was formed. The growth of the buffer layer 30 was performed exclusively in the vertical growth mode. Note that the electron concentration of the buffer layer 30 is 1 ×
It was 10 ¹⁸ / cm ³ . Substrate heating temperature: 730 ° C. Ga source gas: TEG supply amount: 3 × 10 ⁻⁶ atm As source gas: arsine Source gas partial pressure ratio: 200 n-type dopant: Si ₂ H ₆

[Step-320] (Formation of First Cladding Layer 31) Next, n-Al _0.3 Ga is formed on the buffer layer 30 and on the side wall.
_A first cladding layer 31 of _0.7 As was formed (FIG. 5).
(A)). The growth of the first cladding layer 31 was performed in a horizontal growth mode. As a result, the first cladding layer 31 having a thickness of 0.8 μm is formed on the buffer layer 30,
A first cladding layer 31 having a width of 0.4 μm was formed on the side wall of the buffer layer 30. The electron concentration of the first cladding layer 31 was set to 3 × 10 ¹⁷ / cm ³ . Substrate heating temperature: 730 ° C. Ga source gas: TMG Supply amount: 3 × 10 ⁻⁶ atm As source gas: Arsine Source gas partial pressure ratio: 200 n-type dopant: Si ₂ H ₆ Al source gas: TMAl (trimethylaluminum)

[Step-330] (Formation of Active Layer 32) Next, an active layer 32 of GaAs having a thickness of 0.08 μm was formed on the first cladding layer 31. This active layer 3
The growth of No. 2 was performed exclusively in the vertical growth mode. The active layer 32 is not doped. Substrate heating temperature: 730 ° C. Ga source gas: TEG supply amount: 3 × 10 ⁻⁶ atm As source gas: arsine Source gas partial pressure ratio: 200

[Step-340] (Formation of Second Clad Layer 33) Next, a second layer made of p-Al _0.3 Ga _0.7 As is formed on the active layer 32 and on the side walls of the active layer 32 and the first clad layer 31. A cladding layer 33 was formed (see FIG. 5B). The growth of the second cladding layer 33 was performed in a horizontal growth mode. As a result, the second cladding layer 33 having a thickness of 0.8 μm is formed on the active layer 32, and the second cladding layer 3 having a width of 0.4 μm is formed on the side walls of the active layer 32 and the first cladding layer 31.
3 was formed. The hole concentration of the second cladding layer 33 was set to 5 × 10 ¹⁷ / cm ³ . In this case, the p-type second cladding layer 33 can be formed by carbon impurities introduced from TMG, and there is no need to use a p-type doping gas. Substrate heating temperature: 730 ° C. Ga source gas: TMG supply amount: 3 × 10 ⁻⁶ atm As source gas: TMAs source gas partial pressure ratio: 200 Al source gas: TMAl

[Step-350] (Formation of Cap Layer 34) Thereafter, the substrate heating temperature was lowered to 675 ° C., and the cap layer 34 made of p ⁺ -GaAs was formed on the second cladding layer 33 and on the side wall ( (See FIG. 5C). The growth of the cap layer 34 was performed in a horizontal growth mode. As a result, a cap layer 34 having a thickness of 0.4 μm was formed on the second cladding layer 33, and a cap layer 34 having a width of 0.2 μm was formed on the side wall of the second cladding layer 33. The hole concentration of the cap layer 34 was set to 3 × 10 ¹⁸ / cm ³ . The reason for lowering the substrate heating temperature is to increase the hole concentration by increasing the incorporation of carbon. Substrate heating temperature: 675 ° C. Ga source gas: TMG supply amount: 3 × 10 ⁻⁶ atm As source gas: TMAs source gas partial pressure ratio: 200

[Step-360] Finally, an n-type electrode (not shown) is formed on the bottom surface of the substrate 10 and a p-type electrode (not shown) is formed on the cap layer 34 by a usual method. I do.

The first cladding layer 3 is formed on the side wall of the buffer layer 30.
By forming 1, leak current from the second cladding layer 33 to the buffer layer 30 can be prevented. Further, the second cladding layer 33 is formed on the side walls of the active layer 32 and the first cladding layer 31 by the horizontal growth mode, and the cap layer 34 is further grown on the side walls of the second cladding layer 33, so that there is little change with time and stable. Semiconductor laser can be manufactured.

Embodiment 4 In Embodiment 4, based on the MOCVD method of the present invention described above, a heterojunction bipolar transistor (HBT) for driving a semiconductor laser is used.
A semiconductor laser integrated with was fabricated. Semiconductor lasers and HBTs have a lateral structure and are formed on an insulating film on a GaAs substrate. Hereinafter, a method of manufacturing the semiconductor laser integrated with the HBT will be described with reference to FIGS. The supply amount of the source gas was represented by the partial pressure in the MOCVD reactor. The total pressure in the MOCVD reactor was 0.1 atm.

[Step-400] (Preparation of Substrate) First, the window 14 is formed on the (111) B surface of the GaAs substrate 10 by the same method as in [Step-300] of the third embodiment.

[Step-410] (Formation of Basic Layer 40) Next, n is formed on the window 14 of the substrate 10 under the following conditions.
A base layer 40 made of ⁺ -GaAs and having a thickness of 1.0 μm was formed. The growth of the base layer 40 was performed exclusively in the vertical growth mode. Substrate heating temperature: 700 ° C. Ga source gas: TEG supply amount: 2.6 × 10 ⁻⁶ atm As source gas: arsine source gas partial pressure ratio: 200 n-type dopant: Si ₂ H ₆ supply amount: 1 × 10 ⁻⁸ Barometric pressure

[Step-420] (Formation of Emitter Layer 41) Next, the emitter layer 41 made of n-AlGaAs was formed on the base layer 40 and on the side wall. This emitter layer 41
Was grown in the horizontal growth mode. As a result, the emitter layer 41 having a thickness of 0.2 μm is formed on the base layer 40, and the emitter layer 4 having a width of 0.5 μm is formed on the side wall of the base layer 30.
1 was formed. The carrier concentration of the emitter layer 41 was set to 5 × 10 ¹⁷ / cm ³ . Substrate heating temperature: 700 ° C. Ga source gas: TMG supply amount: 2.6 × 10 ⁻⁶ atm As source gas: arsine source gas partial pressure ratio: 800 n-type dopant: Si ₂ H ₆ supply amount: 1 × 10 ⁻⁸ Atmospheric pressure Al source gas: TMAl Supply amount: 0.6 × 10 ^-6 atm

[Step-430] (Formation of Base Layer 42) Next, a base layer 42 made of p-GaAs was formed on the emitter layer 41 and on the side wall. The growth of the base layer 42 was performed in a horizontal growth mode. As a result, a base layer 42 having a thickness of 0.05 μm was formed on the emitter layer 41, and a base layer 42 having a width of 0.15 μm was formed on a side wall of the emitter layer 41. Note that the carrier concentration of the base layer 42 was 1 × 10 ¹⁸ / cm ³ . The p-type base layer 42 can be formed by carbon impurities introduced from TMG. Substrate heating temperature: 700 ° C. Ga source gas: TMG supply amount: 2.6 × 10 ⁻⁶ atm As source gas: TMAs source gas partial pressure ratio: 200

[Step-440] (Formation of Collector Layer 43) Next, a collector layer 43 made of n-GaAs was formed on the base layer 42 and on the side wall (see FIG. 6A).
The growth of the collector layer 43 was performed in a horizontal growth mode. As a result, a collector layer 43 having a thickness of 0.2 μm was formed on the base layer 42, and a collector layer 43 having a width of 0.5 μm was formed on a side wall of the base layer 42. Note that the carrier concentration of the collector layer 43 was 1 × 10 ¹⁶ / cm ³ .

Thus, the emitter layer 41 and the base layer 42
In addition, an npn-type HBT having a lateral structure in which the collector layer 43 is formed on the insulating film 12 is formed. Next, HBT
Next, a semiconductor laser is formed.

[Step-450] (Formation of First Cladding Layer 44) That is, n-AlGaAs is formed on the collector layer 43 and on the side wall.
The first cladding layer 44 of s was formed. This first cladding layer was grown in the horizontal growth mode under the same conditions as in [Step-420]. As a result, the collector layer 4
A first cladding layer 44 having a thickness of 0.2 μm was formed on the layer 3, and a first cladding layer 44 having a width of 0.5 μm was formed on the side wall of the collector layer 43. Note that the carrier concentration of the first cladding layer 44 was set to 5 × 10 ¹⁷ / cm ³ .

[Step-460] (Formation of Active Layer 45) Next, an active layer 45 made of GaAs was formed on the first cladding layer 44 and on the side wall. The growth of the active layer 45 was also performed in the horizontal growth mode. As a result, the first cladding layer 4
4, an active layer 45 having a thickness of 0.03 μm is formed.
The active layer 4 having a width of 0.1 μm is formed on the side wall of the first cladding layer 44.
5 was formed. The active layer 45 was formed under such conditions.
The carrier concentration in it was too low to be measured. TMG
The carrier concentration of the compound semiconductor layer to be formed can be controlled by a combination of / Arsine, a combination of TMG / TMAs, or a combination of TMG / TMAs / Arsine.

[Step-470] (Formation of Second Cladding Layer 46) Then, p-AlGaAs is formed on the active layer 45 and on the side wall.
The second cladding layer 46 made of was formed. The growth of the second cladding layer 46 was performed in a horizontal growth mode. As a result, a second cladding layer 46 having a thickness of 0.2 μm is formed on the active layer 45, and a width of 0.5 μm
Of the second cladding layer 46 was formed. Note that the carrier concentration of the second cladding layer 46 was set to 5 × 10 ¹⁷ / cm ³ . The reason for simultaneously introducing arsine and TMAs is that while achieving the horizontal growth mode, an appropriate hole concentration (5 × 10 ¹⁷
/ Cm ³ ). Substrate heating temperature: 700 ° C. Ga source gas: TMG supply amount: 2.6 × 10 ⁻⁶ atm As source gas: TMAs and arsine Source gas partial pressure ratio: 150 (TMAs) and 50 (arsine) Al source gas: TMAl supply Amount: 0.6 × 10 ^-6 atm

Thus, the first cladding layer 44 and the active layer 4
5 and the second cladding layer 46 formed on the insulating film 12 have a lateral semiconductor laser structure.
It is formed integrally with the BT.

[Step-480] (Formation of Cap Layer 47) Thereafter, p ⁺ -G
A cap layer 47 made of aAs was formed (see FIG. 6B). The growth of the cap layer 47 was performed in the horizontal growth mode. As a result, a cap layer 47 having a thickness of 0.2 μm is formed on the second cladding layer 46, and a cap layer 47 having a width of 0.5 μm is formed on a side wall of the second cladding layer 46.
Was formed. The carrier concentration of the cap layer 47 is set to 3
× 10 ¹⁸ / cm ³ . Substrate heating temperature: 700 ° C. Ga source gas: TMG supply amount: 2.6 × 10 ⁻⁶ atm As source gas: TMAs source gas partial pressure ratio: 200

[Step-490] Next, each compound semiconductor layer above the plane including the top surface of the base layer 40 is etched with a normal alkaline solution. Thereafter, an AuGe / Au electrode 48 is formed on the back surface of the substrate 10, while an AuZn / Au electrode 49 is formed on the base layer 42 and the cap layer 47 using a normal lithography technique. Next, an annealing process of 450 ° C. × 20 seconds is performed. In this way, an HBT and a semiconductor laser having a lateral structure integrated in the horizontal direction on the insulating film 12 shown in FIG. 7A are formed. FIG. 7B shows an equivalent circuit diagram. Finally, by using an appropriate end face forming technique (for example, cleavage or etching), laser light is emitted in a direction perpendicular to the plane of FIG.

Example 5 In Example 5, a horizontal pin photodiode was manufactured based on the MOCVD method of the present invention described above. Hereinafter, a horizontal pin photodiode will be described with reference to FIG. 8, but the supply amount of the source gas is represented by a partial pressure in the MOCVD reactor. The total pressure in the MOCVD reactor was 0.1 atm.

[Step-500] (Preparation of Substrate) First, the window 14 is formed on the (111) B surface of the GaAs substrate 10 by the same method as in [Step-300] of the third embodiment.

[Step-510] (Formation of n-type layer 50) Next, n is formed on the window 14 of the substrate 10 under the following conditions.
^A 1.5 μm thick n-type layer 50 made of ⁺ −GaAs was formed. The growth of the n-type layer 50 was performed exclusively in the vertical growth mode. Substrate heating temperature: 700 ° C. Ga source gas: TEG supply amount: 2.6 × 10 ⁻⁶ atm As source gas: arsine source gas partial pressure ratio: 200 n-type dopant: Si ₂ H ₆ supply amount: 1 × 10 ⁻⁸ Barometric pressure

[Step-520] (Formation of i-layer 51) Next, an i-layer (light absorption layer) 51 made of i-GaAs was formed on the n-type layer 50 and on the side walls. This i-layer 51 was grown in a horizontal growth mode. As a result, an i-layer 51 having a thickness of 0.5 μm is formed on the n-type layer 50,
The i-layer 51 having a width of 2 μm was formed on the side wall of the zero. Substrate heating temperature: 700 ° C. Ga source gas: TMG supply amount: 2.6 × 10 ⁻⁶ atm As source gas: arsine and TMAs source gas partial pressure ratio: 50 (arsine / TMG) 150 (TMAs / TMG) By simultaneously introducing arsine and TMAs as As source gases, the carrier concentration of the i-layer 51 can be reduced.

[Step-530] (Formation of p-type layer 52) Thereafter, a p-type layer 52 made of p-GaAs was formed on the i-layer 51 and on the side wall (see FIG. 8A). This p
The growth of the mold layer 52 was performed in the horizontal growth mode. As a result, a p-type layer 52 having a thickness of 0.2 μm is formed on the i-layer 51, and a p-type layer 52 having a width of 0.5 μm is formed on a side wall of the i-layer 51.
Was formed.

[Step-540] Next, each compound semiconductor layer above the plane including the top surface of the n-type layer 50 was etched with a normal alkaline solution (see FIG. 8B). . As a result, a horizontal pin photodiode is formed.

[Step-550] (Formation of Light Transmitting Layer 53) Thereafter, the light transmitting layer 53 made of i-AlGaAs is entirely formed.
Was formed. The growth of the light transmitting layer 53 was performed exclusively in the vertical growth mode. As a result, a light transmitting layer 53 having a thickness of 0.3 μm was formed on the entire surface. Substrate heating temperature: 700 ° C. Ga source gas: TEG supply amount: 2.6 × 10 ⁻⁶ atm As source gas: arsine source gas partial pressure ratio: 200 Al source gas: TMAl supply amount: 0.6 × 10 ⁻⁶ atm

[Step-560] Next, an AuGe / Au electrode 54 is formed on the back surface of the substrate 10, while AuZn / Au is formed on the p-type layer 52 by using a normal lithography technique.
The electrode 55 is formed and an annealing process is performed at 450 ° C. × 20 seconds. Thus, a highly sensitive photodetector having a large light absorption layer in the horizontal direction on the insulating film 12 as shown in FIG. 8C can be manufactured.

(Embodiment 6) In Embodiment 6, based on the MOCVD method of the present invention described above, GaAs-O
An n-Insulator was formed. Hereinafter, this forming method will be described with reference to FIG. 9, but the supply amount of the raw material gas is represented by the partial pressure in the MOCVD reactor. Also, M
The total pressure in the OCVD reactor was 0.1 atm.

[Step-600] (Preparation of Substrate) First, the window 14 is formed on the (111) B surface of the GaAs substrate 10 by the same method as in [Step-300] of the third embodiment.

[Step-610] (Formation of First GaAs Layer 60) Next, the first GaAs layer 60 having a thickness of 0.1 μm was formed on the window 14 of the substrate 10 under the following conditions. The growth of the first GaAs layer 60 was performed exclusively in the vertical growth mode. Substrate heating temperature: 700 ° C. Ga source gas: TEG supply amount: 2.6 × 10 ⁻⁶ atm As source gas: TMAs source gas partial pressure ratio: 200

[Step-620] (Formation of Second GaAs Layer 61) Thereafter, the second Ga layer is formed on the first GaAs layer 60 and on the side wall.
An As layer 61 was formed (see FIG. 9). This second GaAs
The growth of the layer 61 was performed in the horizontal growth mode. as a result,
A second Ga layer having a thickness of 0.2 μm is formed on the first GaAs layer 60.
An As layer 61 was formed, and a second GaAs layer 61 having a width of 2 μm was formed on a side wall of the first GaAs layer 60. 1st Ga
The sheet carrier concentration of the entire As layer 60 and the second GaAs layer 61 was 1 × 10 ¹² / cm ³ . In addition, GaAs
The total thickness of the layers 60 and 61 is 0.3 μm. Substrate heating temperature: 700 ° C. Ga raw material gas: TMG supply amount: 2.6 × 10 ⁻⁶ atm As raw material gas: arsine Raw material gas partial pressure ratio: 600

Thereafter, the second Ga is formed by using a normal processing technique.
A transistor having a TFT structure can be formed over the As layer 61. With the structure including the insulating film 12, the short channel effect can be prevented.

Although the present invention has been described based on the preferred embodiments, the present invention is not limited to these embodiments. Various conditions described in the examples are examples,
It can be changed as appropriate. In growing the compound semiconductor crystal layer in the horizontal direction of the substrate, trimethylgallium is used as a Ga source gas, and T is used as an As source gas.
Instead of MAs, TDMAAs (tris-dimethylaminoarsenic) can also be used. Also, tertiary butyl arsenic can be used instead of arsine.

The MOCVD method of the present invention is applied to the fabrication of a semiconductor laser, the fabrication of an integrated structure of a semiconductor laser and an HBT,
Fabrication of n-type photodiode, GaAs-On-Ins
Although applied to the formation of the ulrator, the invention is not limited to these fields, nor is it limited to the structure described in the embodiment. For example, besides the double hetero structure, for example, a SCH structure, a quantum well structure and the like can be exemplified as the semiconductor laser. Further, the MOCVD method of the present invention can be applied to the manufacture of an LED. The procedure for manufacturing the integrated structure of the semiconductor laser and the HBT may be in the order of the formation of the semiconductor laser and the formation of the HBT. In addition to the integrated structure of the HBT of the semiconductor laser, for example, an LED
And an HBT integrated structure, a photodiode and an HBT integrated structure, and the like. Further, the present invention can be applied to the fabrication of a photodiode other than the pin type photodiode (for example, a photodiode having a pn junction).
An OCVD method can be applied.

[0064]

According to the MOCVD method of the present invention, the growth of the compound semiconductor crystal layer in the substrate vertical direction and the substrate horizontal direction is achieved by changing the composition of the Ga source gas and the As source gas. It can be controlled arbitrarily by controlling the partial pressure ratio of the Ga source gas. At this time,
The growth of the compound semiconductor crystal layer in the substrate vertical direction and the substrate horizontal direction can be obtained without changing the substrate heating temperature (or within a small temperature range even if it is changed). Therefore, it is not necessary to interrupt the crystal growth of the compound semiconductor layer (even if it is interrupted in a short time), it is possible to prevent the occurrence of defects on the surface of the compound semiconductor layer.

Further, in growing the compound semiconductor crystal layer, trimethyl arsenic is used as the As source gas, so that the p-type layer can be easily formed by carbon doping which has been impossible in the prior art. Further, by using trimethyl arsenic and arsine together, the carrier concentration in the compound semiconductor layer can be easily controlled.

By using the MOCVD method of the present invention, a device having a lateral structure can be easily formed by a series of crystal growth processes.

[Brief description of the drawings]

FIG. 1 is a schematic partial cross-sectional view of a substrate and the like for explaining an MOCVD method of the present invention.

FIG. 2 is a schematic partial cross-sectional view of a substrate, a compound semiconductor layer, and the like for explaining the MOCVD method of the present invention, following FIG.

FIG. 3 is a graph showing a change in a crystal growth rate in a substrate vertical direction and a substrate horizontal direction when a type of a source gas and a source gas partial pressure ratio are changed.

FIG. 4 is a graph showing a change in a crystal growth rate in a substrate vertical direction and a substrate horizontal direction when a substrate heating temperature is changed.

FIG. 5 is a schematic partial cross-sectional view of a substrate, a compound semiconductor layer, and the like for explaining a manufacturing process of a semiconductor laser of Example 3.

FIG. 6 is a schematic partial cross-sectional view of a substrate, a compound semiconductor layer, and the like for explaining a manufacturing process of an integrated structure of a semiconductor laser and an HBT according to a fourth embodiment.

FIG. 7 is a schematic view showing the semiconductor laser of Example 4 and H
It is a typical fragmentary sectional view of a substrate, a compound semiconductor layer, etc. for explaining a manufacturing process of an integrated structure of BT.

FIG. 8 is a schematic partial cross-sectional view of a substrate, a compound semiconductor layer, and the like for describing a manufacturing process of a pin photodiode of Example 5.

FIG. 9 shows a GaAs-On-Insulato of Example 6.
FIG. 4 is a schematic partial cross-sectional view of a substrate and a compound semiconductor layer for explaining a method of forming r.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 GaAs substrate 12 insulating film 14 window 20 GaAs layer 30 buffer layer 31, 44 first cladding layer 32, 45 active layer 33, 46 second cladding layer 34, 47 cap layer 40 base layer 41 emitter layer 42 base layer 43 collector layer 48, 49, 54, 55 electrode 50 n-type layer 51 i-layer 52 p-type layer 53 light transmission layer 60 first GaAs layer 61 second GaAs layer

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-90166 (JP, A) JP-A-2-273917 (JP, A) JP-A-63-143810 (JP, A) JP-A-2- 165679 (JP, A) JP-A-2-137316 (JP, A) JP-A-2-203520 (JP, A) JP-A-5-41529 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) H01L 21/205

Claims (5)

(57) [Claims] 1. A substrate made of GaAs, having a {110} plane in a substrate horizontal direction and a (111) plane in a substrate vertical direction on a (111) B plane of a substrate made of GaAs, and having at least a Ga element and an As element. A metal organic chemical vapor deposition method for growing a compound semiconductor crystal layer containing triethylgallium as a Ga source gas, wherein the compound semiconductor crystal layer is grown in a substrate horizontal direction. In growing the layer, an organometallic gas is used, wherein trimethylgallium is used as a Ga source gas, trimethylarsenic is used as an As source gas, and a partial pressure ratio of As source gas / Ga source gas is 100 or more. Phase growth method. 2. The method according to claim 1, wherein in growing the compound semiconductor crystal layer in the horizontal direction of the substrate, trimethylgallium is used as a Ga source gas, and trimethylarsenic and arsine are used as an As source gas. The organometallic vapor phase epitaxy described. 3. The method according to claim 1, wherein the growth of the compound semiconductor crystal layer in the direction perpendicular to the substrate uses triethylgallium as a Ga source gas and arsine as an As source gas. 3. The metalorganic vapor phase epitaxy described in 1. above. 4. A substrate heating temperature for growing a compound semiconductor crystal layer in a direction perpendicular to the substrate is 650 ° C. to 850 ° C.
The metal organic chemical vapor deposition method according to any one of claims 1 to 3, wherein 5. The metal organic chemical vapor deposition method according to claim 1, wherein the compound semiconductor crystal layer contains an Al element.