JPH11329980A - Organic metallic gaseous phase growing device and method therefor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an MOVPE device and an MOVPE method for ensuring the uniformity of both carrier concentration and compounds in an epitaxial crystal growth layer. SOLUTION: This device is provided with a susceptor 2 on which a substrate 3 is arranged, reaction gas is allowed to flow in parallel or almost in parallel to a surface 3a of the substrate and a surface 2a of the susceptor, and plural gas channels 5 and 6 are arranged in parallel to a plane including the surface of the susceptor, so as to be made mutually independent through a partition wall part 5a provided in parallel or almost in parallel to a plane including the surface of the susceptor at the upstream side of the susceptor 2. Then, a gas outflow port 5A of the gas channel 5 arranged so as to be made closest to the plane including the surface of the susceptor is positioned at an upstream side edge part 2A of the susceptor, and a gas outflow port 6A of the gas channel 6 arranged so as to be made farthest to the plane including the surface of the susceptor is positioned at an upstream side by 10-30 mm from an upstream side edge part 3A of the substrate.

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 apparatus and a metal organic chemical vapor deposition method using the same, and more particularly, to forming an epitaxial crystal growth layer of a III-V compound semiconductor on a substrate. When the film is formed, the composition of the grown crystal in the growth layer can be made uniform, and when the growth layer is a conductive type layer, the variation in the carrier concentration can be reduced. Field effect transistor (FET), high electron mobility transistor (HEMT), hetero bipolar transistor (H
The present invention relates to a metal organic chemical vapor deposition apparatus useful for manufacturing an epitaxial wafer for a semiconductor device such as BT) and a metal organic chemical vapor deposition method using the same.

[0002]

2. Description of the Related Art For example, a wafer used for manufacturing a GaAs HEMT or HBT is an example of a HEMT wafer in which a plurality of epitaxial crystal growth layers made of a GaAs compound semiconductor having a predetermined composition are stacked on a GaAs substrate. 7 and FIG. 8 showing an example of an HBT wafer, and the semiconductor material constituting each epitaxial crystal growth layer is usually GaAs or AlGaAs.
s, InGaAs, and InGaP are used. These growth layers are typically formed by metal organic chemical vapor deposition (MOVPE).
It is formed by a method.

FIG. 9 shows an example of an apparatus for performing the MOVPE method. The device shown in FIG. 9 is a horizontal device,
A reactor 1 having a gas inlet 1a and a gas outlet 1b;
A susceptor 2, usually made of carbon, disposed at a substantially central position of the reaction furnace 1, and a GaAs disposed on the susceptor 2.
An s substrate 3 is provided. The susceptor 2 is provided with, for example, an IR lamp 4 so that the susceptor and the substrate 3 disposed thereon can be heated and maintained at the growth temperature of the epitaxial crystal.

In this device, II such as Ga, Al, In, etc.
A reaction gas in a reaction furnace 1 at a predetermined flow rate is obtained by mixing a source gas of a group I element, a source gas of a group V element such as As and P, and H _{2 as a} carrier gas.
Supplied within.

In this case, for example, triethyl gallium (TEGa) is used as a Ga source, trimethyl aluminum (TMAl) is used as an Al source, trimethyl indium (TMIn) is used as an In source, and arsine (As) is used as an As source.
As the H ₃ ) and P sources, phosphine (PHs) or the like is used as a source gas. The mixing ratio of these source gases is appropriately determined in relation to the target composition of the grown crystal in the growth layer to be formed.

[0006] As indicated by arrows in the figure, the reaction gas flows in the reaction furnace 1 in a flow substantially parallel to the surface 2a of the susceptor 2 and the surface 3a of the substrate 3, and the gas outlet 1
It is discharged from b.

[0007] In this process, an epitaxial crystal growth reaction occurs on the surface 3a of the substrate 3, and a crystal growth layer of a III-V compound semiconductor having a predetermined composition and thickness is formed on the substrate.

In this process, the substrate 3 is rotated. This is for averaging the distribution generated in the gas flow direction.

When the growth layer to be formed is an n-type layer, for example, disilane (Si ₂
A reaction gas formed by mixing an n-type dopant gas such as H ₆ ) is supplied to the reaction furnace 1. At this time, the flow rate of Si ₂ H ₆ is determined in relation to the target carrier concentration in the n-type layer to be formed.

[0010]

By the way, when a GaAs-based compound semiconductor is epitaxially grown by the MOVPE apparatus shown in FIG. 9, the composition of the grown crystal of the growth layer formed on the substrate is changed at the growth position on the substrate. In some cases, when the growth layer is a conductive type layer, the carrier concentration may vary in a growth portion on the same substrate.

One example will be described below.

First, the following four types of growth layers were designed.

An n-type GaAs growth layer: a film thickness of 50 nm and a carrier concentration of 3 × 10 ¹⁸ cm ⁻³ .

An n-type AlGaAs growth layer: a film thickness of 10 nm, a carrier concentration of 3 × 10 ¹⁸ cm ⁻³ , and a target composition of Al of 0.25.

I-type InGaAs growth layer: 14 nm thick, I
Target composition 0.20 for n.

[0016] n-type InGaP growth layer: thickness 30 nm, a carrier concentration of 5 × 10 ¹⁷ cm ^-3, target composition 0.48 In.

Each raw material gas was supplied into the reaction furnace 1 at the flow rates shown in Table 1. At this time, the n-type GaAs
At the time of forming the s growth layer, the n-type AlGaAs growth layer, and the n-type InGaP growth layer, Si ₂ H ₆ was further supplied at a predetermined flow rate corresponding to the respective target carrier concentrations.

[0018]

[Table 1]

A GaAs substrate was used as a substrate, and while rotating the substrate, the growth layers of the semiconductors shown in Table 1 were separately formed on the GaAs substrate while the growth temperatures were set at 580 ° C. and 610 ° C. Was formed.

Then, the film thickness, carrier concentration, and crystal composition of each growth layer were measured, and the target film thickness, the target carrier concentration, and the dispersion of the measured values with respect to the target composition were calculated. . Note that n-type AlGa
The composition of the As growth layer and the i-type InGaAs growth layer was measured by the PL method, and the composition of the InGaP growth layer was measured by the X-ray diffraction method. Table 2 shows the results.
Shown in

[0021]

[Table 2]

As is clear from Table 2, in the case of the n-type GaAs growth layer and the n-type AlGaAs growth layer, the variation in the film thickness changes little even if the growth temperature is 580 ° C. or 610 ° C. Absent. That is, the uniformity of the film thickness is realized without depending on the growth temperature. However, the carrier concentration has a greater variation as the growth temperature decreases. That is, the uniformity of the carrier concentration depends on the growth temperature, and becomes worse as the growth temperature becomes lower.

In the case of an n-type InGaP growth layer, the lower the growth temperature, the smaller the variation in composition and carrier concentration.

Next, an n-type Al film formed on a GaAs substrate
For the GaAs growth layer, the carrier concentration at each position on the surface was measured. The results are shown in FIG. 10 as a relationship with the distance from the center point of the GaAs substrate. The scale on the vertical axis in FIG. 10 is a value obtained by dividing the measured value at each position by the average value of all the measured values, and-○-mark indicates that when the growth temperature is 580 ° C.,-● The-marks indicate the results when the growth temperature was 610 ° C, respectively.

As is apparent from FIG. 10, the growth temperature is 6
In the case of 10 ° C., the change in the carrier concentration from the center to the periphery of the substrate is small, and the uniformity of the carrier concentration in the n-type AlGaAs growth layer is relatively well ensured. However, when the growth temperature is 580 ° C., the carrier concentration in the growth layer decreases as approaching the peripheral portion, and the uniformity is extremely poor. That is, at the time of forming the n-type AlGaAs growth layer, uniformity of the carrier concentration can be secured by increasing the growth temperature.

Also, an i-type In film formed on a GaAs substrate
For the GaAs growth layer, In at each position on the surface
Was measured. The results are shown in FIG. 11 as a relationship of the distance from the center point of the GaAs substrate. Note that FIG.
The scale of the vertical axis in the middle is a value obtained by dividing the measured value at each position by the In composition at the center point of the substrate, and-○-mark indicates that the growth temperature is 580 ° C, and-●-mark indicates the growth. The results when the temperature is 610 ° C. are shown.

As is clear from FIG. 11, the growth temperature is 5
In the case of 80 ° C., the composition of the grown crystal in the growth layer has no variation from the central point to the peripheral portion, and uniformity of the composition is secured. However, a growth temperature of 6
When the temperature is set to 10 ° C., the In composition decreases as approaching the peripheral portion, and deviates from the target composition. That is, i-type InGa
When forming the As growth layer, uniformity of composition can be ensured by setting the growth temperature to a low temperature.

As described above, in the case of manufacturing a HEMT wafer, for example, with the MOVPE apparatus shown in FIG. 9, when the apparatus is operated at a reduced growth temperature, the uniformity of the grown crystal in the obtained i-type growth layer is ensured. However, on the other hand, in the obtained n-type growth layer, the carrier concentration is reduced toward the periphery, and the uniformity is deteriorated. When the operation is performed with the growth temperature increased, the uniformity of the carrier concentration in the obtained n-type growth layer is ensured, but in the i-type growth layer, the composition of the grown crystal shifts from the target composition toward the periphery side. The properties of the hetero-junction interface will be impaired, and the step punching will increase, and the properties of the heterojunction interface will be impaired. That is, in the case of the MOVPE apparatus shown in FIG. 9, there is a problem that it is difficult to achieve both uniformity of the composition of the grown crystal and uniformity of the carrier concentration in the obtained growth layer.

The present invention relates to the conventional MOVPE shown in FIG.
An MOVPE device having a structure capable of solving the above-described problem that occurs during operation of the device, and by using the device, uniformity of carrier concentration in a growth layer can be ensured even when a growth temperature is set to a low temperature. At the same time, since the growth temperature is low, uniformity of the composition of the grown crystal in the grown layer can be ensured, and the characteristics of the MOVPE method which does not impair the characteristics of the heterojunction interface between the grown layers to be formed. For the purpose of providing.

[0030]

Means for Solving the Problems In the course of research for achieving the above-mentioned object, the present inventors have studied the MO shown in FIG.
The following considerations were made regarding the operation of the VPE device.

(1) First, the phenomenon that when the growth temperature is set to a high temperature, the uniformity of the composition of the grown crystal in the i-type growth layer deteriorates is due to the following reason.

The reaction gas supplied to the reaction furnace 1 is preheated at a portion of the susceptor located upstream of the substrate before flowing to the surface of the substrate. As the growth temperature increases, the upstream portion of the susceptor also increases in temperature, and thus the temperature of the reaction gas also increases. Therefore, II in the reaction gas
The source gas of the group I element causes thermal decomposition on the upstream side of the substrate surface, and the crystal must be grown on the downstream side of the substrate surface.
Group I elements become depleted. As a result, even if the substrate is rotated, it is presumed that the crystal grown on the periphery of the substrate has a reduced composition of Group III elements.

(2) On the other hand, if Si ₂ H ₆ is used as an n-type dopant source when the growth layer is an n-type layer, the doping efficiency at that time is, for example, the following formula: AsH ₃ + Si ₂ H ₆ → SiH ₃ AsH ₂ + SiH ₄ It is considered that the rate is determined by the reaction (1). The above reaction proceeds more efficiently at higher temperatures. Therefore,
It is estimated that the higher the growth temperature is set, that is, the higher the temperature of the reaction gas is preheated in the upstream portion of the susceptor, the better the uniformity of the carrier concentration in the growth layer becomes.

(3) However, in the case of the conventional MOVPE apparatus shown in FIG.
Since the reaction gas, which is a mixed gas of the raw material gas of the group III element and Si ₂ H ₆ , is supplied from one gas inlet and flows to the substrate 3, each component gas is the same in the upstream portion of the susceptor 2. It will be preheated to temperature.

Therefore, if the growth temperature on the substrate is set to a low temperature suitable for the source gas of the group III element in order to ensure the uniformity of the composition,
The reaction based on the equation (1) does not proceed efficiently, and the achievement of uniformity of the carrier concentration is hindered. Conversely, if the growth temperature is increased, the reaction of the formula (1) proceeds efficiently and the uniformity of the carrier concentration is ensured, but on the other hand, the realization of the uniformity of the composition is hindered.

(4) The problem of the conventional apparatus is that the source gas of the group III element and the source gas of the group V element are supplied in a mixed state with Si ₂ H ₆ , and each of these component gases is supplied to the substrate surface. Caused by the susceptor being preheated to the same temperature before reaching.

Therefore, first, the raw material gas of the group III element
And Group V source gas and Si_TwoH ₆Separate flow path with
And a susceptor for the group III element source gas
To reach the substrate surface in a state where the preheating by
Group V element source gas and Si_TwoH₆To the susceptor
If it reaches the substrate surface with accelerated preheating,
Ensures uniform carrier concentration when forming conductive type layers
And the uniformity of the composition during the formation of the i-type layer.
It is thought that oneness can be secured.

The present inventors have conducted studies based on the above considerations. Then, the MOVPE apparatus of the present invention and the MOVPE method using the same have been developed.

That is, the MOVPE apparatus of the present invention has a susceptor on which a substrate is disposed, and the MOVPE apparatus in which a reaction gas flows parallel or substantially parallel to the surface of the substrate and the surface of the susceptor. On the upstream side of the susceptor, a plurality of gas flow paths independent of each other are arranged in parallel with the plane including the surface of the susceptor via a partition provided in parallel or substantially parallel to the plane including the surface of the susceptor. The gas outlet of a gas flow path (hereinafter, referred to as a first gas flow path) disposed closest to a plane including the surface of the susceptor is located at an upstream end of the susceptor. A gas flow path disposed farthest from a plane including the surface of the susceptor (hereinafter, referred to as a second gas flow path)
Gas outlet is 10 to 30 times higher than the upstream end of the substrate.
mm upstream.

In the present invention, the above-described MOVP
E using an E-apparatus that is closest to the plane containing the surface of the susceptor.
Raw material gas of the group V element
And H _Two(Hereinafter, referred to as a first reaction gas)
), And the most from the plane containing the surface of the susceptor
Raw material of group III elements from a gas channel located far away
Gas and H_Two(Hereinafter, referred to as a second reaction gas)
) To supply III-V compound semiconductor epitaxy
MOVPE method characterized by forming a crystal growth layer
Is further provided, using the MOVPE apparatus described above,
Located closest to the plane containing the susceptor surface
The raw material gas of the group V element and H_TwoAnd Si_TwoH₆When
Supplying a reaction gas comprising the surface of the susceptor
III from the gas channel located farthest from the plane
Group element raw material gas and H_TwoAnd supplying a reaction gas consisting of
II-V compound semiconductor n-type epitaxial crystal growth layer
MOVPE method characterized in that
You.

[0041]

FIG. 1 shows the basic structure of the device of the present invention. This apparatus (I) is a horizontal apparatus, in which a substrate 3 placed on a susceptor 2 heated by an IR lamp (not shown) is installed in a reaction furnace 1.
The flow of the reaction gas as a flow parallel or substantially parallel to the surface 2a of the susceptor 2 and the surface 3a of the substrate 3 is not different from the conventional apparatus shown in FIG.

However, in the device (I) of the present invention,
Two gas flow paths 5 and 6 are provided upstream of the susceptor 2, and different types of reaction gases can be supplied from the gas flow paths 5 and 6 into the furnace.

The gas flow paths 5, 6 are formed independently of each other via a partition wall 5a such as a partition plate provided in parallel or substantially parallel to a plane including the surface 2a of the susceptor 2. Specifically, there are two gas flow paths parallel to a plane including the surface 2a of the susceptor.
Each reaction gas supplied into the reaction furnace 1 from each of the gas passages 5 and 6 flows in a direction parallel or substantially parallel to the surfaces of the susceptor 2 and the substrate 3.

Then, the gas flow path 5, ie, the susceptor 2
The gas outlet 5A of the first gas flow path disposed closest to the surface of the susceptor 2 is located at the same position as the upstream end 2A of the susceptor 2, and the gas flow path 6, ie, the susceptor 2
The gas outlet 6A of the second gas flow path disposed farthest from the surface of the susceptor 2 is the upstream end 2A of the susceptor 2.
It is located further downstream than the upstream end 3A of the substrate 3 by 10 to 30 mm.

In the case of this apparatus (I), when forming an n-type growth layer, the first gas flow path 5 passes through the first gas flow path 5 using a source gas of a group V element, H ₂ and Si ₂ H ₆ . One reactant gas is supplied, and a second reactant gas composed of a group III element source gas and H ₂ is separately supplied from the second gas flow path 6 to advance MOVPE.

In this device (I), the first gas passage 5
The distance of the susceptor 2 from the gas outlet 5A to the substrate 3 is longer than the distance from the gas outlet 6A of the second gas flow path 6 to the substrate 3. Therefore, the degree of preheating of the first reactant gas supplied from the gas outlet 5A in the upstream portion of the susceptor 2 is greater than that of the second reactant gas supplied from the gas outlet 6A. Therefore, when the two kinds of reaction gases reach the substrate 3, the first reaction gas is in a relatively high temperature state and the second reaction gas is in a relatively low temperature state.

Therefore, even when the growth temperature on the substrate is set to a low temperature, (1)
The reaction of the formula proceeds efficiently, and the uniformity of the carrier concentration is also ensured. Of course, since the growth temperature is low, the composition uniformity of the grown crystal is also ensured.

The promotion of the preheating state for the first reaction gas is as follows.
For example, it can be realized by setting the substrate 3 and the susceptor 2 at the same temperature and increasing the length of the upstream portion of the susceptor 2. This is because the distance over which the first reaction gas supplied from the gas outlet 5A is preheated becomes longer. Further, even if the temperature of the substrate 3 is set to a low temperature suitable for ensuring the uniformity of the composition, and the temperature of the upstream portion of the susceptor 2 is set to a high temperature, the preheating of the first reaction gas can be promoted.

Here, the gas outlet 6A of the second gas passage 6
Is set at a position on the upstream side far away from the upstream end 3A of the substrate, the temperature of the second reaction gas on the surface 3a of the substrate becomes too high, and it becomes difficult to ensure the uniformity of the composition. If the position is set too close to the upstream end 3A, the temperature of the second reaction gas on the surface of the substrate becomes low, and it becomes difficult to realize good crystal growth. Upstream end 6 of substrate
It is necessary to set 10 to 30 mm upstream from A.

In the operation of the apparatus (I), the first
When the first reaction gas supplied from the gas flow path 5 and the second reaction gas supplied from the second gas flow path 6 merge and flow, each reaction is performed in order to reduce the disturbance of the gas flow. It is necessary to make the gas average velocities of the gases substantially equal.

More specifically, the gas flow rates from the first gas flow path 5 and the second gas flow path 6 are denoted by V1 and V2, respectively, and the gas passage cross-sectional areas of the gas outlets 5A and 6A are denoted by S1 and S1, respectively.
When S2 is satisfied, the following equation is satisfied: k · V1 / S1 = V2 / S2 (where k is a constant that varies depending on the total flow rate of the gas, the reaction pressure, the temperature of the susceptor, and the like). The operation of the apparatus is controlled as described above.

When an i-type growth layer is formed during the manufacture of the HEMT wafer, a first reaction gas containing no Si ₂ H ₆ is supplied from the first gas flow path 5.

FIG. 2 is a schematic view showing another apparatus (II) of the present invention.

In this device (II), the first gas flow path 5 in the apparatus (I) shown in FIG. 1 is further divided into two parts by partition walls 5b, and the first gas flow path 5 and the second gas flow path Between six,
The first gas flow passage of the gas outlet 5A gas channel provided with a gas outlet 7A in the same position as 7 (hereinafter, a third of the gas flow path) is disposed, the reaction furnace 1 and H ₂ from here It can be supplied to.

In the case of the device (II), in the crystal grown on the surface 3a of the substrate for the same reason as in the case of the device (I), it is possible to ensure both the uniformity of the composition and the uniformity of the carrier concentration. it can. In addition to this, by the action of H ₂ supplied from the third gas flow path 7, the reaction product of the raw material gas in the first reaction gas supplied from the first gas flow path 5 is converted into the second gas flow. An effect that adhesion to the upper partition of the road 6 can be suppressed is also achieved.

In the case of the apparatus (II), when the gas flow rate from the third gas flow path 7 is V3 and the gas passage cross-sectional area of the gas outlet 7A is S3, the following equation is obtained: k · V1 / S1 = V2 / S2 (2) V1 / S1 = V3 / S3 (3) It is necessary to operate the apparatus so that the average gas velocities of the component gases are substantially equal to each other.

FIG. 3 is a schematic view showing still another apparatus (III) of the present invention.

In the device (III), the second gas passage 6 in the device (I) shown in FIG. 1 is further divided into two parts via a partition wall 5c, and the first gas passage 5 and the second gas passage Between six,
A gas passage 8 (hereinafter, referred to as a fourth gas passage) provided with a gas outlet 8A is provided at the same position as the gas outlet 6A of the second gas passage, from which H ₂ is introduced into the reactor 1. It can be supplied to.

Even in the case of the device (III), the device (I)
In the crystal grown on the surface 3a of the substrate for the same reason as in the case (1), it is possible to ensure both uniformity of the composition and uniformity of the carrier concentration. And in addition to that,
By the function of H ₂ supplied from the fourth gas flow path 8, it is possible to suppress a situation in which the second reaction gas supplied from the second gas flow path 6 is preheated in the upstream portion of the susceptor 2.

In the case of the device (III), when the gas flow rate from the fourth gas flow path 8 is V4 and the gas passage cross-sectional area of the gas outlet 8A is S4, the following equation is obtained: k · V1 / S1 = V2 / S2 (2) It is necessary to operate the apparatus so as to satisfy V2 / S2 = V4 / S4 (4) to make the gas average velocities of the component gases substantially equal.

FIG. 4 is a schematic view showing still another apparatus (IV) of the present invention.

This device (IV) has a structure in which the above-mentioned device (II) and device (III) are combined. That is,
A third gas flow path 7 and a fourth gas flow path 8 are provided between the first gas flow path 5 and the second gas flow path 6 in the device (I),
Each gas outlet 5A, 7A of the gas flow path 5 and the third gas flow path 7
Is made the same as the position of the upstream end 2A of the susceptor 3, and the respective gas outlets 6 of the second gas passage 6 and the fourth gas passage 8 are arranged.
Positions A and 8A are 10 to 30 from the upstream end 3A of the substrate.
mm is set on the upstream side.

In the case of the apparatus (IV), it is possible not only to ensure both the uniformity of the composition of the crystal formed on the substrate and the uniformity of the carrier concentration, but also to the apparatus (II) and the apparatus ( The above-mentioned effect in III) can be exhibited at the same time.

In the case of the device (IV), the following equation is used: k · V1 / S1 = V2 / S2 (2) V1 / S1 = V3 / S3 (3) V2 / S2 = V4 / It is necessary to operate the apparatus so as to satisfy S4 (4) so that the average gas velocities of the component gases match.

FIG. 5 is a schematic view showing still another apparatus (V) of the present invention. This device (V) is a barrel type device for mass production.

In this apparatus (V), a rotating substrate 3 is disposed in a vertical reaction furnace 1 having a gas outlet 1b, and a hemispherical cap 2b for preventing turbulence is provided on the upper part. The pyramid-shaped susceptor 2 is installed so as to be able to revolve.

A dome-shaped member 9 is disposed above the susceptor 2 as a partition, and the inside of the reaction furnace 1 is divided into two series of gas flow paths 5 and 6, and the reaction gas flows through each gas flow path. Gases are separately supplied from above to below.
In these gas passages 5 and 6, the gas passages 5 and 6 function as a first gas passage and a second gas passage in the present invention, respectively. And a dome-shaped member (partition wall) 9
The lower end 9a of the susceptor 2 is located downstream of the upstream end 2A of the susceptor 2 and is 10 to 30 mm from the upstream end 3A of the substrate 3.
It is located on the upstream side.

In this device (V), the first gas passage 5
A first gas comprising a group V element source gas, H ₂ and Si ₂ H ₆
A reactant gas is supplied, and a second reactant gas comprising a group III element source gas and H ₂ is supplied to the second gas flow path 6, and the MO gas is supplied.
VPE proceeds.

The first reactant gas (the source gas of the group V element and H ₂ and Si ₂ H ₆ ) supplied to the first gas passage 5 flows from the position of the gas outlet 5A to the upstream portion of the susceptor 2. During the heating, the temperature rises and reaches the substrate 3. on the other hand,
The second reaction gas (the source gas of the group III element and H ₂ ) supplied to the second gas flow path 6 reaches the substrate 3 without being preheated up to the gas outlet 6A. Therefore, also in the case of the apparatus (V), the crystal growth can be advanced on the substrate 3 in a state where the uniformity of the carrier concentration and the uniformity of the composition are both compatible.

FIG. 6 is a schematic view showing an apparatus (VI) of the present invention, and this apparatus (VI) is a parallel type apparatus for mass production.

In this device (VI), the gas outlets 1b, 1
b, a disk-shaped susceptor 2 on which a plurality of substrates 3 rotating on its surface is disposed so as to be able to revolve.

At the center of the lower part of the reactor 1,
Two gas passages 5 and 6 are provided in such a manner that their respective central axes coincide with the central axis of the susceptor 2.
Of the disk-shaped flaw member 10 having a radius of 10 to 30 mm and extending parallel to the surface of the susceptor 2,
Is provided as a partition so that the lower space of the reaction furnace 1 is divided into a first gas flow path 5 and a second gas flow path 6 according to the present invention.

In this device (VI), the first gas passage 5
A first gas comprising a group V element source gas, H ₂ and Si ₂ H ₆
A reactant gas is supplied, and a second reactant gas comprising a group III element source gas and H ₂ is supplied to the second gas flow path 6, and the MO gas is supplied.
VPE proceeds.

The first reactant gas and the second reactant gas are both supplied in the upward direction to the reactor 1 and the gas outlet 5A
The first reactant gas flowing from the substrate hits the surface of the susceptor 2 and flows therefrom in a direction parallel to the surface of the susceptor 2 and flows toward the substrate 3, and reaches the upstream end 3 A of the substrate 3 in the process. The substrate reaches the substrate 3 after being preheated at the susceptor 2 and heated up.

On the other hand, the second reaction gas flowing from the gas outlet 6A strikes the flaw-shaped member (partition part) 10 and flows therefrom in a direction parallel to the surface of the susceptor 3 and flows toward the substrate 3. In the process, it reaches the substrate 3 without being preheated by the susceptor 2.

Accordingly, also in the case of the apparatus (VI), the crystal growth can be advanced on the substrate 3 in a state where the uniformity of the carrier concentration and the uniformity of the composition are both satisfied.

Example 1 The apparatus (I) of the present invention shown in FIG. 1 was operated under the following specifications, and a target film thickness: 10 nm, a target composition of Al: 0.25, a target Carrier concentration: 3 × 1
0 ¹⁸ cm ^-3 n-type AlGaAs growth layer and target film thickness: 14
An i-type InGaAs growth layer having a target composition of nm and In of 0.20 was formed.

First, a GaAs substrate 3 was placed on a susceptor 2 made of graphite, and this was set in a reaction furnace 1 as shown in FIG. Here, the distance between the upstream end 3A of the GaAs substrate 3 and the upstream end 2A of the susceptor 2 is set to 80 mm.

There are only two gas flow paths in the reactor 1, a first gas flow path 5 and a second gas flow path 6.
The ratio of the gas passage cross-sectional area of the second gas flow path 5 to that of the second gas flow path 5 is 2: 1. The gas outlet 5A of the first gas passage 5 is located at the same position as the upstream end 2A of the susceptor, and the gas outlet 6A of the second gas passage 6 is located closer to the upstream end 3A of the GaAs substrate 3. Is also located 20 mm upstream.

The raw material gas used and the flow rate thereof are as specified in Table 1 above, and the total flow rate of the reaction gas is 18 slm.
(Standard liter per minute).
Therefore, based on the equation (2) and setting k = 2.1, the flow rate V1 of the first reaction gas from the first gas flow path 5 is 8.8 slm, and the flow rate V1 of the first reaction gas from the second gas flow path 6 is 2. The flow rate V2 of the reaction gas is controlled to be 9.2 slm.

Further, with respect to the heating mode of the susceptor 2 and the GaAs substrate 3, the following two modes were adopted.

A: Both the GaAs substrate 3 and the susceptor 2 are heated equally to 580 ° C.

B: The GaAs substrate 3 was heated to 580 ° C.
The upstream part of the susceptor 2 is heated to 610 ° C.

The device was operated under the above conditions, and GaAs
An n-type AlGaAs growth layer and an i-type InGaAs growth layer were formed on the substrate.

For comparison, the same apparatus as in Example 1 was used except that the apparatus used was the conventional apparatus shown in FIG. 7 and the reaction gas used was a mixture of the respective source gases. MOVPE was performed under the following operating conditions.

The thickness, carrier concentration and crystal composition of each of the obtained growth layers were measured, and the variation with respect to the target value was calculated. The results are collectively shown in Table 3.

[0087]

[Table 3]

As is apparent from Table 3, n-type AlGaAs
The uniformity of the carrier concentration in the s growth layer can be improved by setting the temperature of the upstream portion of the susceptor to 610 ° C. even when the substrate temperature is lowered to 580 ° C. in both Example 1 and Comparative Example. This is because, even if the growth temperature on the GaAs substrate is as low as 580 ° C., if the heating mode is B, the preheating of the first reaction gas can proceed in the upstream portion of the susceptor 2.

However, as for the In composition in the i-type InGaAs growth layer, when the heating mode is set to B, the variation is small in Example 1 and extremely large in Comparative Example. This is because the upstream portion of the susceptor 2 has a high temperature of 610 ° C., and in the comparative example, the source gas of the group III element is also preheated at the same time. On the contrary,
In the case of the first embodiment, since the preheating of the group III element source gas is suppressed, the variation of the In composition does not occur.

As described above, it is difficult to achieve both the uniformity of the carrier concentration in the growth layer and the uniformity of the composition in the conventional apparatus. However, the apparatus (I) of the present invention can achieve both. it can.

Embodiment 2 In the apparatus (I) shown in FIG. 1, the distance between the upstream end 3A of the GaAs substrate 3 and the upstream end 2A of the susceptor 2 is set to 1
20 mm, and both the GaAs substrate 3 and the susceptor 2 were heated at the same temperature of 580 ° C.
Under the same operating conditions as in Example 1, an n-type AlGaAs growth layer and an i-type InGaAs growth layer were formed.

At this time, the variation in carrier concentration in the n-type AlGaAs growth layer is ± 2.2%, and i
Variation in the In composition in the p-type InGaAs growth layer is ±
It was less than 1%.

That is, even if the growth temperature on the GaAs substrate is set to a low temperature, the first reaction gas containing the group V element source gas is sufficiently preheated to a high temperature because the upstream portion of the susceptor 2 is long. On the substrate, the reaction represented by the formula (1) proceeds efficiently, and the uniformity of the carrier concentration is secured. At the same time, since the substrate surface is at a low temperature of 580 ° C., the uniformity of the composition of the group III element is ensured.

[0094]

As is apparent from the above description, the MOVPE apparatus of the present invention has a separate flow path for the source gas for the group V element and the source gas for the dopant source and a different flow path for the source gas for the group III element. The structure is such that the source gas is preheated by the susceptor so that a difference is generated. Therefore, when the MOVPE method is performed using this apparatus, even if the growth temperature on the substrate is set to a low temperature, the growth layer Uniformity of carrier concentration can be ensured. Also, if this device is used, i
The uniformity of the crystal composition in the growth layer of the mold can also be ensured at the same time.

Further, when the MOVPE apparatus of the present invention is used, it is possible to form a growth layer at a low temperature, so that an epitaxial wafer having excellent quality can be obtained without impairing the characteristics of the heterojunction interface between the semiconductor layers. Can be manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an apparatus (I) of the present invention.

FIG. 2 is a schematic view showing an apparatus (II) of the present invention.

FIG. 3 is a schematic view showing an apparatus (III) of the present invention.

FIG. 4 is a schematic diagram showing an apparatus (IV) of the present invention.

FIG. 5 is a schematic diagram showing an apparatus (V) of the present invention.

FIG. 6 is a schematic view showing an apparatus (VI) of the present invention.

FIG. 7 is a sectional view showing an example of a sectional structure of the HEMT.

FIG. 8 is a sectional view showing a sectional structure of the HBT.

FIG. 9 is a schematic view showing a conventional device.

FIG. 10 is a graph showing a carrier concentration distribution in an n-type AlGaAs growth layer formed by a conventional apparatus.

FIG. 11 is a graph showing a change in In composition in an i-type InGaAs growth layer formed by a conventional apparatus.

[Explanation of symbols]

Reference Signs List 1 reactor 1a gas inlet of reactor 1 1b gas outlet of reactor 1 2 susceptor 2a surface of susceptor 2b hemispherical cap 2A upstream end of susceptor 2 3 substrate 3a surface of substrate 3 3A upstream of substrate 3 Side end 4 IR lamp 5 First gas flow path (gas flow path closest to the surface of susceptor 2) 5A Gas outlets 5a, 5b, 5c of first gas flow path 5 Partition plate (partition wall) 6 Second gas Channel (gas channel farthest from the surface of susceptor 2) 6A Gas outlet of second gas channel 6 7 Third gas outlet 7A Gas outlet of third gas channel 7 8 Fourth gas channel 8A 4 Gas outlet 8 of gas passage 8 9 Dome-shaped member (partition wall) 9a Lower end of dome-shaped member 9 10 Scratched member (partition wall)

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI H01L 21/338 29/812

Claims (3)

[Claims] 1. A metal organic chemical vapor deposition apparatus having a susceptor on which a substrate is disposed, wherein a reaction gas flows parallel or substantially parallel to the surface of the substrate and the surface of the susceptor. A plurality of gas channels independent of each other are arranged in parallel with the plane including the surface of the susceptor via a partition provided in parallel or substantially parallel to the plane including the surface of the susceptor, and the surface of the susceptor The gas outlet of the gas flow path disposed closest to the plane including the susceptor is located at the upstream end of the susceptor, and the gas flow outlet disposed farthest from the plane including the surface of the susceptor. The gas outlet of the passage is 10 meters above the upstream end of the substrate.
An organometallic vapor phase epitaxy apparatus, which is located about 30 mm upstream. 2. The method according to claim 1, wherein a gas flow path provided at a position closest to a plane including the surface of the susceptor includes a source gas of a group V element and H _2. reaction gas comprising supplying said from the gas flow path disposed in the farthest position from the plane including the surface of the susceptor by supplying a reaction gas consisting of the raw material gas and H ₂ of the group III element III-
A metal organic chemical vapor deposition method characterized by forming an epitaxial crystal growth layer of a group V compound semiconductor. 3. A metal gas vapor phase epitaxy apparatus according to claim 1, wherein a source gas of a group V element, H _2, and S are supplied from a gas flow path disposed closest to a plane including the surface of the susceptor.
A reaction gas composed of i ₂ H ₆ is supplied, and a reaction gas composed of a group III element source gas and H ₂ is supplied from a gas flow path disposed farthest from a plane including the surface of the susceptor. Forming an n-type epitaxial crystal growth layer of a group III-V compound semiconductor by vapor deposition.