JP2000044385A - Gas rectifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas rectifier of simple structure designed to afford uniform gas flow irrespective of flow rate and pressure condition. SOLUTION: This gas rectifier has such a design and scheme that, there are a flat gas inlet pipe 12 of uniform height and an exhaust accumulation chamber 13 provided with an opening and communicating with the gas inlet pipe 12; wherein the gas inlet pipe 12 is sufficiently longer than the exhaust accumulation chamber 13, and the height of the exhaust accumulation chamber 13 is sufficiently greater than that of the gas inlet pipe 12; since the pressure difference inside the gas inlet pipe 12 is greater than that inside the chamber 13, a parallel gas flow is afforded inside the gas inlet pipe 12, while a bent flow inside the chamber 13; furthermore, inside the gas inlet pipe 12 and on the upstream side thereof, gas flow rate distribution is rendered uniform in the cross direction rectangular to the gas flow.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rectifier, and more particularly to a gas rectifier, and more particularly to a gas rectifier connected downstream of a reaction chamber in a vapor phase growth apparatus to rectify the flow of the reaction chamber.

[0002]

2. Description of the Related Art Metal organic vapor phase growth is one of the vapor phase growth techniques.
se Epitaxy (hereinafter abbreviated as “MOVPE”) is one of the crystal growth techniques for compound semiconductor lasers.

FIG. 6 is a schematic diagram showing a reaction chamber of a MOVPE crystal growth apparatus. Referring to FIG. 6, in this apparatus, a substrate 2 for growing MOVPE crystal and a susceptor 5 for supporting substrate 2 are provided in reaction chamber 7. A source gas inlet 1 is connected to one side of the reaction chamber 7, and an exhaust port 8 is connected to the other side. The exhaust port 8 is further connected to an exhaust mechanism 6 for exhausting exhaust gas generated in the reaction chamber 7. The pressure in the reaction chamber 7 can be changed by adjusting the exhaust amount of the exhaust mechanism 6.
In addition, the entire reaction chamber 7 is inserted through the susceptor 5 into the lumen of the high-frequency coil 4 for heating the substrate. Cooling water 3 circulates around the outer periphery of the reaction chamber 7 to cool the reaction chamber 7. A pipe (not shown) is connected to the source gas inlet 1, and a source gas and a carrier gas are supplied to the reaction chamber 7 through the pipe and the source gas inlet 1.

Next, a method for producing a MOVPE crystal using this apparatus will be described.

Referring to FIG. 6 again, the raw material gas is mixed with a carrier gas such as hydrogen or nitrogen, and the mixed gas flows into reaction chamber 7 through a piping (not shown) and further through raw material gas inlet 1. By heating the susceptor 5 by applying a high-frequency current to the high-frequency coil 4, the raw material is thermally decomposed on the substrate 2 to start crystal growth.

The outline of the MOVPE growth method has been described so far. However, the present invention is not limited to the MOVPE growth method, and a vapor phase growth apparatus generally has a structure in which a plurality of gases are mixed and introduced into a reaction chamber. Then, in the reaction chamber, the mixed gas flows on the heated substrate, the raw material is decomposed, and crystals grow on the substrate.

In order to make the crystal growth rate and crystal quality uniform, it is necessary to make the gas flow on the substrate uniform. Hitherto, there has been proposed a structure in which the inner diameter of a pipe for supplying a source gas to a reaction chamber is gradually enlarged toward the reaction chamber (see Japanese Patent Application Laid-Open No. 60-199494).

FIG. 7 is a view for explaining such a conventional piping structure. Referring to FIG. 7, in this conventional piping structure, the width and the cross-sectional area gradually decrease in the flow direction (toward the reaction chamber) downstream of the tubular gas introduction pipe 61 having the same sectional diameter. Horn 63 being expanded to
Is connected.

According to this conventional piping structure, the gas introduced into the gas introduction piping 61 passes through the introduction port 62, largely spreads in the horn 63, and is exhausted from the discharge port 64.

Further, in order to make the crystal growth rate and the quality of the crystal uniform, the shape of the gas exhaust portion is also important as in the above-described shape of the gas introduction portion.

Referring to FIG. 6 again, generally, the exhaust port 8
Is smaller than the size of the reaction chamber 7, the exhaust port 8
If the flow of the exhaust part is biased due to the influence of the position and the exhaust speed, the flow velocity distribution on the substrate 2 is also affected.

Japanese Patent Application Laid-Open No. Hei 5-306468 proposes a plasma vapor deposition apparatus for making the flow velocity distribution uniform on a substrate placed in a reaction chamber. FIG. 8 is a diagram for explaining this plasma vapor deposition apparatus.

Referring to FIG. 8, in this conventional apparatus, a plurality of sub exhaust ports 102 are connected to a reaction chamber 101 on which a plurality of substrates 105 are placed, and the plurality of sub exhaust ports 102 are connected to one. A main exhaust port 104 is connected to each of the secondary exhaust ports 102.
In this apparatus, the dampers 103 are respectively provided in the middle of the apparatus, and the opening speeds of the plurality of dampers 103 are adjusted to adjust the exhaust speed, thereby making the flow speed on the plurality of substrates 105 uniform.

Japanese Patent Application Laid-Open No. Hei 6-13368 discloses that
In the reaction chamber, as gas rectification means for uniformly flowing the reaction gas from the center portion of the substrate to the outer periphery, on the outer periphery of the substrate,
There has been proposed a structure in which a gas flow regulating plate having discharge holes arranged in an annular shape is provided.

In the structure proposed in the above-mentioned Japanese Patent Application Laid-Open No. 6-13368, gas supplied to the substrate through a large number of through-holes arranged above the substrate reacts on the substrate and reacts on the gas rectifying plate on the outer periphery of the substrate. Are discharged to the outside of the reaction chamber through the annularly arranged discharge holes provided in the nozzles and the annular grooves communicating with these discharge holes.

Further, Japanese Patent Application Laid-Open No. H10-55968 proposes a semiconductor processing apparatus for preventing clogging of an exhaust port due to attached matter.

FIGS. 9 (a) and 9 (b) show Japanese Unexamined Patent Publication No.
FIG. 1 is a diagram for explaining a semiconductor processing device proposed in Japanese Patent No. 5968. Referring to FIGS. 9A and 9B, in this semiconductor processing apparatus, a substrate 83 is provided in a reaction chamber.
Is mounted, and a heater 82 is arranged above the substrate 83. A gas inlet 81 is provided above the substrate 83, that is, in a central portion above the reaction chamber, and an exhaust port 86 for exhausting gas to the outside of the reaction chamber is formed below the outer peripheral frame of the reaction chamber.

Further, the reaction chamber serves as a gas rectifier for flowing the supplied gas radially from the vicinity of the center of the substrate 83 to the vicinity of the outer periphery. Annular slit 85 communicating with the hole
And the width of the annular slit 85 is reduced near the exhaust port 86. Thus, the exhaust gas to be sucked is not biased to the vicinity of the exhaust port 86.

[0019]

However, the above-mentioned prior art has the following problems.

The first problem is that the structure for rectification is complicated.

The reason is described in, for example, the above-mentioned JP-A-5-30.
A conventional device as proposed in US Pat. No. 6,468,
This is because, in order to adjust the exhaust speed of the plurality of exhaust ports, a mechanism for detecting the exhaust speed at each exhaust port and adjusting the opening of the damper by a separately input control signal is required.

The second problem is that the rectifier is connected to the downstream side of the reaction chamber of the vapor phase growth apparatus. In particular, when the width of the reaction chamber is wide and gas is exhausted from a single exhaust port, The uniformity of the film thickness distribution and crystal quality of the crystal formed on the substrate is reduced.

The reason is that the difference between the cross-sectional area of the reaction chamber and the cross-sectional area of the exhaust port of the reaction chamber is large, so that the exhaust is biased,
This is because a flow velocity distribution occurs on a substrate placed in the reaction chamber, that is, at a place where crystal growth is performed.

A third problem is that, in the exhaust portion connected to the downstream side of the reaction chamber of the vapor phase growth apparatus, the downstream side of the exhaust portion is formed into a horn shape (see Japanese Patent Application Laid-Open No. 60-1994).
In other words, when a structure in which the flow cross-sectional area gradually increases is applied to the exhaust part, the growth rate and quality of the crystals formed on the substrate may not be uniform.

The reason is that, depending on the state of reduced pressure or when the flow velocity is high, the flow cannot be sufficiently widened unless the horn shape is made extremely long.

The fourth problem is that the above-mentioned Japanese Patent Application Laid-Open No.
In the conventional apparatus as proposed in Japanese Patent Publication No. 8-208, there is a risk that the substrate is contaminated or the annularly arranged exhaust holes are clogged.

[0027] The reason for this is that, when a turbulence or a backflow occurs, the deposits remaining inside the annular grooves communicating with the exhaust ports in the annular arrangement are scattered.

A fifth problem is that the above-mentioned Japanese Patent Application Laid-Open No. H10-559
Conventional devices, such as that proposed in US Pat. No. 68, tolerate only small mechanical errors.

The reason is that in this conventional device,
This is because, in order to keep the flow rate of the exhaust flow within a predetermined range, the width of the slit through which the exhaust flow passes must be made extremely strictly.

Specifically, in this conventional device, the width of the annular slit is reduced near the exhaust port, so that
The exhaust flow from the center of the substrate toward the outer periphery is made uniform. In the case of this structure, the flow velocity of the exhaust flow is 0.5 m /
It is substantially required to be in the range of s to 10 m / s. Therefore, in order to obtain a desired pumping speed, it is necessary to narrow the width of the narrow region in the annular slit to 3.5 mm. When the slit width is reduced in this way, even a slight difference in slit width loses uniformity of the exhaust flow. For example, if the reactant adheres non-uniformly in the vicinity of the slit, the uniformity of the flow easily deteriorates because the slit width is narrow.

An object of the present invention is to provide a rectifier that forms a uniform flow regardless of flow velocity and pressure conditions without requiring a complicated structure or control.

[0032]

According to a first aspect of the present invention, there is provided a first flow path having a flat and uniform height, and an opening communicating with the first flow path and through which a fluid is introduced or discharged. And a length of the first flow path in the flow direction,
It is longer than the length of the second flow path in the same direction, and the height of the first flow path is lower than the height of the second flow path.

According to a second aspect of the present invention, in a second aspect, an annular first flow path having a flat and uniform height communicates with the first flow path at an outer peripheral surface or an inner peripheral surface of the flow path. An annular second flow path provided with a fluid inlet or outlet.
The length of the flow path in the radial direction is longer than the length of the second flow path in the same direction, and the height of the first flow path is lower than the height of the second flow path. Features.

According to a third aspect of the present invention, there is provided a rectangular conduit having a flat and uniform height, an opening for introducing or discharging gas, and a rectangular conduit connected to one end of the conduit. And a gas reservoir, wherein the length of the conduit is longer than the length of the gas reservoir, and the height of the conduit is lower than the gas reservoir.

According to a fourth aspect of the present invention, there is provided an annular conduit having a flat and uniform height and an opening for introducing or discharging a fluid, wherein the conduit and an outer peripheral surface or an inner peripheral surface of the conduit are provided. An annular gas chamber connected at the surface;
A radial length of the conduit is longer than a radial length of the gas reservoir, and a height of the conduit is lower than a height of the gas reservoir.

Hereinafter, the principle of the present invention will be described with reference to the drawings. However, the description with reference to the following drawings is for facilitating the understanding of the present invention, and does not limit the scope of the present invention in any way.

Since a fluid such as gas has viscosity, the pressure loss increases as the sectional area of the structure through which the gas passes and as the length increases.

Thus, referring to FIGS. 1A to 1C, the length of the tubular gas introduction pipe (first flow path) 12 is reduced by the length of the rectangular exhaust accumulation chamber (second flow path) 13. By making it sufficiently longer than the length and making the height of the gas introduction pipe 12 sufficiently lower than the height of the exhaust chamber 13, the pressure difference between the upstream and the downstream of the gas introduction pipe 12 becomes large. Thus, the pressure difference between the upstream side and the downstream side in the exhaust chamber 13 becomes smaller than the pressure difference in the gas introduction pipe 12.

Further, since the fluid flows through a path having the smallest pressure difference, that is, a path that is easy to flow, a parallel flow is formed in the gas introduction pipe 12 along the pipe axis direction.
In the exhaust chamber 13, the flow is bent and heads toward the exhaust port 14.

More specifically, as shown in FIG. 1B, the gas introduced from the vicinity of the center of the gas introduction pipe 12 is indicated by arrows A → B
→ C is discharged from the gas exhaust port 14 through a path such as C, while the gas introduced from the vicinity of the pipe wall of the gas introduction pipe 12 passes through a path such as the arrow D → E → C. 1
It is discharged from 4.

The gas exhaust port 14 is connected to the exhaust chamber 1
Despite being formed only at the center in the width direction of 3,
In the gas introduction pipe 12, as shown by a solid line in FIG. 2 (in the case where a gas rectifier is provided), the width direction (G in FIG.
The flow velocity distribution in the (−H direction) becomes constant. In a normal conduit (without a gas rectifier), the flow velocity near the center of the pipe is high, the flow velocity near the pipe wall is low, and a large flow velocity distribution is formed in the width direction.

Next, taking a case where the first flow path and the second flow path are configured so as to form a radially uniform flow,
The principle of the present invention will be described.

Referring to FIGS. 4 (a) and 4 (b), the radial length of the flat and annular gas introduction chamber (first flow path) 55 is changed to the annular exhaust accumulation chamber (second flow path) 56. And the height of the gas introduction pipe 12 is set longer than the radial length of the exhaust chamber 13.
Is lower than the height of the gas introduction chamber 55.
In such a case, the gas flows radially from the inside to the outside along the radial direction along a path close to the shortest distance so as to minimize the pressure difference. Then, the flow is guided to the exhaust port 57 in the exhaust chamber 56. Thus, a uniform gas flow radially outward from the center of the reaction chamber 58 in the radial direction is formed in the reaction chamber 58 connected to the inner peripheral side of the annular gas introduction chamber.

[0044]

Next, a preferred embodiment of the present invention will be described.

In a preferred embodiment of the rectifier of the present invention, the first flow path is a tubular flow path (the gas introduction pipe 1 in FIG. 1).
2), the second flow path is a rectangular chamber (exhaust chamber 13 in FIG. 1), and a parallel flow (FIG. 1) flowing in the first flow path along the pipe axis direction toward the second flow path. Arrows D → E and arrows A → B in (b) are formed, and part or all of the parallel flow is bent in the second flow path (arrows E → C in FIG. 1 (b)). ),
A flow toward the opening (the connection portion of the gas exhaust port 14 in FIG. 1) is formed.

In a preferred embodiment of the rectifier of the present invention, the first flow path is a tubular flow path (the gas discharge pipe 9 in FIG. 5).
3), the second flow path is a rectangular chamber (exhaust chamber 92 in FIG. 5), and is opened in the second flow path (gas inlet 9 in FIG. 5).
Part or all of the flow of the fluid introduced from the (1 connection part) is bent and the flow is expanded, and the flow expanded in the first flow path becomes a parallel flow flowing along the pipe axis direction.

In a preferred embodiment of the rectifier of the present invention, the width of the first flow path in the direction orthogonal to the flow direction and the height direction is uniform along the flow direction, and the width of the second flow path is the same. Are uniform along the flow direction. Further, preferably, the widths of the first flow path and the second flow path are the same.

In a preferred embodiment of the rectifier of the present invention, the first flow path (gas introduction chamber 55 in FIGS. 4A and 4B) and the second flow path (FIGS. 4A and 4B) The exhaust chamber 56) is annular and communicates with each other in the radial direction, so that a radial flow flowing in the radial direction is formed in the first flow path, and the radial flow is bent in the second flow path. As a result, a flow toward the opening (the exhaust port 57 connection portion in FIG. 4) is formed.

In a preferred embodiment of the rectifier of the present invention, the first flow path and the second flow path are annular, and are communicated with each other in the radial direction, so that the fluid introduced from the opening in the second flow path can be formed. A part or all of the flow is bent to expand the flow, and the expanded flow becomes a radial flow flowing in the first flow path in the radial direction.

In a preferred embodiment of the rectifier of the present invention, the second flow path is provided with a plurality of openings. Thereby, the first flow path and the flow path connected to the upstream or downstream side of the first flow path (the reaction chamber 35 in FIG. 3, the reaction chamber 58 in FIG. The flow velocity distribution in the connected flow path) is further narrowed and uniformized, and the accuracy of the flow velocity control can be improved. Further, the allowable range of the height ratio between the first flow path and the second flow path is widened, and the degree of freedom in design is improved.

In a preferred embodiment of the rectifier of the present invention, the ratio of the height of the first flow path to the height of the second flow path is determined by setting the height of the first flow path to the height of the second flow path = 1: 2. As described above, a sufficient effect can be obtained. In particular, when hydrogen is mainly supplied, the height ratio is preferably set to 1: 2 or more. Further, it is preferable that the height ratio is 1: 4 or more. In addition, it is preferable that the height ratio between the first flow path and the second flow path be set optimally according to the type of gas or the temperature of the gas.

When using gases having various viscosities,
The pressure difference between the upstream part and the downstream part of the first flow path when the gas with the lowest viscosity is used among the gases used, and the upstream part of the exhaust chamber (connection part with the first flow path) So that the ratio of the pressure difference between the pressure and the downstream portion (opening) is 2: 1 or more.
Setting the length and height of the first channel and the second channel,
More effective.

When the height of the first flow path is increased, the pressure difference in the first flow path can be sufficiently ensured by increasing the length of the first flow path. The length of the first channel and the second
The ratio of the lengths of the channels is as follows: first channel length: second channel length = 4:
It is preferably at most 3, more preferably at most 3: 2 and at most 2: 1.

FIGS. 1 (a) to 1 (c) and FIGS. 5 (a) to 5 (a)
In (c), the opening of the second flow path is formed at the bottom surface of the second flow path, but the opening is formed at another location, for example, at the side surface or the upper surface of the second flow path, Even when the gas exhaust / inlet (gas exhaust / inlet 41, 91) is connected, the effect of the present invention can be obtained.

In general, since the viscosity of a gas does not depend much on the pressure, the present invention is applicable to a wide range of pressures. The viscosity of the gas changes depending on the type of the gas and the temperature of the gas. In particular, when the temperature distribution in the width direction occurs in the first flow path and the second flow path, the flow resistance changes depending on the position, so the pressure loss in the first flow path and the second flow path also changes, and the flow velocity in the width direction changes The difference becomes large. Therefore, it is preferable that the temperature be uniform along the width direction of the flow path.

Further, in the rectifier of the present invention, in a preferred embodiment, a sufficient effect can be obtained even if the height of the first flow path is 10 mm or more, so that the reaction product adheres to the first flow path. The effect can be reduced. Specifically, there is little possibility that the height of the first flow path changes over time due to adhesion of a reaction product or the like, and it is possible to reduce a pressure change over time.

[0057]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to further clarify the embodiment of the present invention described above, an embodiment of the present invention will be described below with reference to the drawings.

[First Embodiment] FIGS. 1 (a) to 1 (c)
It is a figure for explaining the structure of the gas rectifier concerning a 1st example of the present invention, (a) is a side view, (b) is a top view,
(C) is a perspective view.

Referring to FIGS. 1A to 1C, this gas rectifier has a rectangular exhaust chamber 13 at the downstream end of a flat gas introduction pipe 12 extending in the horizontal direction. They are connected to communicate. An opening is formed in the center of the downstream side of the bottom surface of the exhaust chamber 13 and a gas exhaust port 14 extending in the vertical direction is connected. The width (horizontal direction) and height (vertical direction) of the gas introduction pipe 12 are uniform along the gas flow direction, that is, the cross-sectional area perpendicular to the same direction is uniform, and the exhaust chamber 13 Are also uniform along the same direction, that is, the cross-sectional area perpendicular to the same direction is uniform, and the gas introduction pipe 12 and the exhaust chamber 1
3 have the same width.

Further, the length of the gas introduction pipe 12 is formed long enough to form a sufficiently developed flow. In addition, the height of the gas introduction pipe 12 is
Is formed sufficiently lower than the height.

Next, the function of the gas rectifier will be described.

Referring to FIGS. 1A to 1C, in this gas rectifier, the pressure difference between position A and position B, that is, the pressure difference between both ends of gas introduction pipe 12, is large.
Between the position B and the position C, that is, the exhaust chamber 13
Is small.

The reason is that the width of the gas introduction pipe 12 is the same as the width of the exhaust chamber 13, but the height of the gas introduction pipe 12 is sufficiently lower than the height of the exhaust chamber 13, This is because the length is sufficiently longer than the length of the exhaust chamber 13.

Here, when a fluid such as gas passes through the pipe, the pressure loss increases as the cross-sectional area of the pipe decreases and as the pipe length increases, due to the viscosity of the fluid. Then, the fluid passes through a path having the smallest pressure difference, that is, a path that easily flows.

Therefore, as shown by arrows in FIG. 1B, the gas flows in the gas introduction pipe 12 in parallel with the pipe wall along the pipe axis direction (D → E, A → B). In the exhaust chamber 13, the gas near the pipe wall bends and flows toward the exhaust port 14 connected to the opening located at the center (E → C).

That is, from the position D near the pipe wall, the gas introduced into the gas introduction pipe 12 passes through a path such as D → E → C to the opening at the center of the downstream portion of the exhaust chamber 13. The gas is discharged from the connected gas exhaust port 14.

Next, the flow velocity distribution in the width direction perpendicular to the flow in the gas introduction pipe 12 will be described. FIG. 2 shows G in FIG.
It is a figure which shows the flow velocity distribution of -H direction. The solid line shows the flow velocity distribution according to the present embodiment, and the broken line shows the flow velocity distribution in a normal pipe not connected to the exhaust chamber.

As shown by the solid line in FIG. 2, according to the present embodiment, although only one gas exhaust port 14 is connected to the center of the exhaust chamber 13, the width of the gas introduction pipe 12 in the width direction is reduced. The flow velocity distribution becomes almost constant.

Further, in this embodiment, the bottom surface of the exhaust chamber 13 and the bottom surface of the gas introduction pipe 12 are on the same horizontal plane, and the exhaust chamber 13 is higher than the gas introduction pipe 12. However, the height of the exhaust chamber 13 may be increased in other directions, for example, downward.

In the gas rectifier according to the present embodiment, preferably, the ratio of the height of the gas introduction pipe 12 and the height of the exhaust chamber 13 is set to 1: 4. Further, as a preferred example of the dimensions, the height of the gas introduction pipe 12 is 10 mm, the length is 200 mm, and the width is 40 mm.
0 mm. The height of the exhaust chamber 13 is 40 mm, the length is 150 mm, and the width is 400 mm.

Next, the gas rectifier described above is connected to the MOV
An example in which the present invention is applied to a PE crystal growth apparatus will be described.

FIG. 3 is a perspective view for explaining the MOVPE crystal growth apparatus using the gas rectifier according to one embodiment of the present invention shown in FIGS. 1 (a) to 1 (c).

Referring to FIG. 3, the MOVPE crystal growth apparatus has a rectangular reaction chamber 35 in which a substrate 37 is placed inclined with respect to a horizontal plane. The substrate 37 is supported on a susceptor 38 in the reaction chamber 35. Susceptor 38
Below, a substrate heater 36 is provided as a heating mechanism for heating the substrate 37.

The outlet 34 of the gas expansion rectifier 33 is connected to the upstream side of the reaction chamber 35. Gas expansion rectifier 3
A pipe 32 extending in the vertical direction is connected to the upper part of the upstream part of the pipe 3, and a mixed gas obtained by mixing a source gas and a carrier gas is supplied through the pipe 32. The gas rectifier according to the embodiment is connected to the downstream side of the reaction chamber 35. As described above, this gas rectifier includes the gas introduction pipe 39 (12 in FIG. 1) and the exhaust chamber 40 (13 in FIG. 1), and the gas introduction pipe 39 is connected to the downstream end face of the reaction chamber 35. , Both are in communication. A gas exhaust port 41 is connected to an opening of the exhaust chamber 40, and a downstream side of the gas exhaust port 41 is connected to an exhaust mechanism 42. The pressure in the reaction chamber 35 can be changed by adjusting the exhaust amount of the exhaust mechanism 42.

It should be noted that the gas expansion rectifier 33 is disclosed in
No. 317272, which has a function of expanding the flow of gas.

Here, the reaction chamber 35 is preferably formed in a rectangular shape so that the effect of the gas rectifier is remarkably exhibited. Further, it is preferable that the downstream section of the reaction chamber 35 be rectangular in accordance with the cross-sectional shape of the flat gas introduction pipe 39. Furthermore, it is preferable that the cross-sectional areas of the two are the same.

The material of the susceptor 38 is desirably a material such as carbon or molybdenum which is stable even at a high temperature with respect to a carrier gas or a raw material. As a method of heating the susceptor 38, resistance heating may be performed using the substrate heater 36 as shown in FIG. 3, or electromagnetic induction heating using high frequency or lamp heating using infrared light may be performed.

The MOVPE described with reference to FIG.
The function of the crystal growth apparatus will be described.

In MOVPE crystal growth, an organic metal such as trimethylaluminum, trimethylgallium, and trimethylindium and a hydride such as arsine and phosphine are used as raw materials, and the raw materials are changed according to the crystal to be grown.
For example, when growing an AlGaAs compound semiconductor crystal, trimethyl aluminum and trimethyl gallium,
Using arsine as a raw material.

These raw materials are mixed in a carrier gas such as hydrogen or nitrogen and flown as a mixed gas 31 through a pipe 32. This mixed gas 31 flows into the gas expansion rectifier 33 through the pipe 32. The gas expansion rectifier 33
Is flattened and uniformly expanded, and the flattened and uniformly expanded gas is introduced into the reaction chamber 35. In the reaction chamber 35, the source gas contained in the mixed gas 31 is thermally decomposed on the plurality of heated substrates 37, and predetermined crystals grow on the substrates 37.

Here, due to the rectification effect of the gas rectifier provided on the downstream side, the flow velocity on the plurality of substrates 37 is uniform, so that the crystal growth rate along the direction perpendicular to the flow is uniform. . Then, exhaust gas is exhausted from the reaction chamber 35 to the gas exhaust port 41 and further to the exhaust mechanism 42 through the gas rectifier according to the embodiment of the present invention described in detail above.

Further, the gas rectifier according to the present invention has a merit that a predetermined effect is obtained not only under normal pressure conditions but also under reduced pressure conditions, so that the gas rectifier has a wide range of application with respect to pressure and does not limit crystal growth conditions.

[Second Embodiment] Next, a gas rectifier according to a second embodiment of the present invention and an MO using the gas rectifier will be described.
The VPE crystal growth apparatus will be described. The gas rectifier according to the first embodiment has a tubular gas introduction pipe and gas flows in the axial direction of the gas. However, the gas rectifier according to the present embodiment has an annular gas introduction chamber and extends radially from the center. The gas is configured to flow radially outward.

FIGS. 4A and 4B show a gas rectifier according to a second embodiment of the present invention and an MO using the gas rectifier.
It is a figure for demonstrating a VPE crystal growth apparatus, (a)
Is a plan sectional view, and (b) is a side sectional view.

Referring to FIGS. 4 (a) and 4 (b), the gas rectifier according to the present embodiment has an annular flat gas introduction chamber 55 on the inner periphery and an annular exhaust chamber 56 on the outer periphery. . On the outer peripheral surface of the gas introduction chamber 55 and the inner peripheral surface of the exhaust chamber 56, both are communicated in the radial direction. Gas introduction room 5
5 is made sufficiently longer than the radial length of the exhaust chamber 56, while the height of the gas introduction chamber 55 is made sufficiently lower than the height of the exhaust chamber 56. ing. A plurality of openings are formed in the outer peripheral surface of the exhaust chamber 56 so as to be circumferentially separated from each other, and a plurality of exhaust ports 57 are connected to the plurality of openings.

Next, MOVPE using this gas rectifier
The crystal growth apparatus will be described.

In this MOVPE crystal growth apparatus, the flat and circular outer peripheral surface of the reaction chamber 58 and the inner peripheral surface of the annular gas introduction chamber 55 are connected to each other. A source gas inlet 51 is provided at the upper center of the reaction chamber 58. On the other hand, in the lower part of the reaction chamber 58, the reaction chamber 58
A plurality of substrates 53 are placed on the susceptor 52 symmetrically with respect to the center. A substrate heater 54 is disposed below the susceptor 52.

Next, the functions of the gas rectifier and the MOVPE crystal growth apparatus will be described.

The raw material gas inlet 5 at the upper center of the reaction chamber 58
The raw material gas introduced from 1 flows outward in the radial direction, reacts with the substrate 53 being heated at this time, and the exhaust gas further flows outward in the radial direction.
5 is introduced. Here, since the radial length of the gas introduction chamber 55 is sufficiently longer than the length of the exhaust chamber 56 in the same direction, and the height of the gas introduction chamber 55 is sufficiently lower than the height of the exhaust chamber 56, The radial pressure difference in the gas introduction chamber 55 is large, while the radial pressure difference in the exhaust chamber 56 is small.

As described above, since the fluid flows along a path in which the pressure difference becomes small, the exhaust gas flows in the gas introduction chamber 55 from the center of the reaction chamber 58 outward in the radial direction, that is, the shortest. Flow radially along the path. Then, in the exhaust chamber 56, the flow of the exhaust gas is bent, and the exhaust gas flows along the circumferential direction and is discharged from each exhaust port 57.

As described above, since the exhaust gas flow downstream of the reaction chamber 58, that is, the exhaust gas flow in the gas introduction chamber 55 is radially outward from the center of the reaction chamber 58, the gas flow in the reaction chamber 58 is reduced. A radial flow is symmetrical with respect to the central axis of the reaction chamber 58, and a uniform gas flow is generated for the plurality of substrates 53.

In the MOVPE crystal growth apparatus described above, referring to FIG. 4B, it is preferable that the height ratio between the gas introduction chamber 55 and the exhaust chamber 56 is 1: 2 or more. For example, the height of the gas introduction chamber 55 is 10 mm, and the ratio of the height of the gas introduction chamber 55 to the height of the exhaust chamber 56 is 1: 4.

Thus, the height of the gas introduction chamber 55 is
Even when the thickness is not less than mm, a sufficient effect of the present invention can be obtained.

The reason is that in the MOVPE crystal growth apparatus to which the gas rectifier according to the present embodiment is applied, the pressure changes due to the substantial change in the height of the gas introduction chamber 55 due to the adhesion of the residue to the gas introduction chamber 55. This is because the effect of the change in the difference is smaller than the structure proposed in Japanese Patent Application Laid-Open No. H10-55968 described above.

In the structure disclosed in Japanese Patent Application Laid-Open No. H10-55968, there is a mechanism for adjusting the width of the annular slit in order to obtain a desired gas flow velocity. By increasing the length of the chamber 55 in the radial direction, the pressure difference can be increased, and a mechanism for adjusting the height of the gas introduction chamber 55 becomes unnecessary.

In a conventional crystal growth apparatus having a structure in which a gas is introduced from the center of a circular reaction chamber and the gas flows outward in the radial direction, the film thickness formed on the substrate is made uniform. To rotate the susceptor,
A rotation mechanism for rotating the substrate is provided.

The reason is that it is difficult to form a uniform gas flow radially outward from the center in the reaction chamber.

On the other hand, according to the crystal growth apparatus using the gas rectifier according to the present embodiment, referring to FIGS. 4A and 4B, the gas rectifier connected downstream of the reaction chamber 58 As a result, a uniform radial gas flow from the center to the radially outward direction is formed in the reaction chamber 58,
A rotating mechanism for revolving the susceptor 52 becomes unnecessary.

[Third Embodiment] Next, a gas rectifier according to a third embodiment of the present invention will be described.

This gas rectifier has the same mechanical structure as the gas rectifier according to the first embodiment, but the gas flow direction is opposite to that of the first embodiment, and the gas exhaust port The names of the elements have been changed such that the gas inlet is a gas inlet, the exhaust chamber is a gas inlet, the gas inlet is a gas outlet, and the gas inlet is a gas outlet. In the following description, functional differences between the present embodiment and the first embodiment will be mainly described, and particularly the same parts relating to the mechanical structure will be appropriately omitted to avoid duplication.

FIGS. 5A to 5C are views for explaining the structure of a gas rectifier according to a third embodiment of the present invention, where FIG. 5A is a side view and FIG. 5B is a plan view. , (C) is a perspective view.

Referring to FIGS. 5A to 5C, in this gas rectifier, gas is introduced from gas introduction port 91 connected to an opening formed in the center of the upstream portion of the bottom surface of gas introduction chamber 92. Gas is introduced into the chamber 92, and the introduced gas flows into the gas discharge pipe 93 and is discharged from a gas discharge port 94 formed at a downstream end of the gas discharge pipe 93.

As described above in the first embodiment, the height of the gas discharge pipe 93 is sufficiently lower than the height of the gas introduction chamber 92, and the length of the gas discharge pipe 93 is sufficiently longer than the length of the gas introduction chamber 92. Have been long. As a result, the pressure difference in the gas discharge pipe 93 becomes sufficiently larger than the pressure difference in the gas introduction chamber 92.
The gas flows so as to minimize the pressure difference, and a parallel flow is formed. That is, the gas flow is expanded in the gas introduction chamber 92, and the expanded gas flow is parallel to the pipe axis (tube wall) in the gas discharge pipe 93 and has a uniform flow velocity distribution in the width direction (flow section direction). The flow is rectified.

In this manner, a gas flow having an enlarged flow cross-sectional area and a uniform flow velocity distribution in the width direction is formed from the flow of the thin gas flowing through the pipe (gas inlet 91) and the like.

Here, the gas discharge pipe 93 and the gas introduction chamber 92
Is preferably 1: 2 or more. The reason is that a sufficient pressure difference is obtained in the gas discharge pipe 93.

[Fourth Embodiment] Next, a fourth embodiment of the present invention will be described. In the gas rectifier according to the third embodiment, the gas flow direction is opposite to the gas rectifier according to the first embodiment. However, in the gas rectifier according to the fourth embodiment of the present invention, The gas flow direction is opposite to that of the gas rectifier according to the second embodiment.

That is, referring to FIGS. 4 (a) and 4 (b), contrary to the second embodiment, gas is introduced from each exhaust port 57 and expanded in the exhaust chamber 56.
In the gas introduction chamber 55, the expanded flow is rectified into a radially uniform flow and supplied to the reaction chamber 58.

[0108]

A first effect of the present invention is that a uniform gas flow can be obtained with a simple structure without requiring a complicated structure or control of a movable portion or the like.

The second effect is that, when the gas rectifier according to the present invention is connected to the downstream side of the reaction chamber of a vapor phase growth apparatus or, in particular, a MOVPE apparatus, the influence of the adhesion of reaction products is small, and a wide range of flow rates and pressure conditions are obtained. In the above, the velocity distribution in the reaction chamber is reduced, that is, the gas flow in the reaction chamber is made uniform. As a result, it is expected that a crystal film having a uniform thickness is grown even on one substrate placed in the reaction chamber or on different substrates.

[Brief description of the drawings]

FIGS. 1A to 1C are diagrams for explaining a gas rectifier according to a first embodiment of the present invention, wherein FIG. 1A is a side view, FIG. c) is a perspective view.

FIG. 2 is a diagram showing a flow velocity distribution in the GH direction in FIG. 1 (b), wherein a solid line shows an example and a broken line shows a flow rate distribution of a comparative example.

FIG. 3 is a perspective view for explaining a crystal growth apparatus using the gas rectifier shown in FIG.

FIGS. 4A and 4B are views for explaining a gas rectifier according to a second embodiment of the present invention and a crystal growth apparatus using the gas rectifier, wherein FIGS. Plan sectional view,
(B) is a side sectional view.

5A and 5B are views for explaining a gas rectifier according to a third embodiment of the present invention, wherein FIG. 5A is a side view, FIG. 5B is a plan view, and FIG. 5C is a perspective view.

FIG. 6 is a schematic diagram of a conventional MOVPE crystal growth apparatus.

FIG. 7 is a schematic diagram showing an example of a conventional horn-shaped gas expanding rectifier.

FIG. 8 is a schematic view showing a gas rectifier according to a conventional example for controlling a gas flow in a reaction chamber by opening and closing a damper.

FIGS. 9A and 9B are schematic views showing a gas rectifier provided with an annular slit communicating with a circular reaction chamber according to a conventional example, where FIG. 9A is a side sectional view and FIG. ) Is a plan sectional view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Gas introduction port 12 Gas introduction pipe 13 Exhaust chamber 14 Gas exhaust port 31 Mixed gas 32 Pipe 33 Gas expansion rectifier 34 Gas expansion rectifier discharge port 35 Reaction chamber 36 Substrate heater 37 Substrate 38 Susceptor 39 Gas introduction pipe 40 Exhaust chamber 41 Gas exhaust port 42 Exhaust mechanism 51 Source gas inlet 52 Susceptor 53 Substrate 54 Substrate heater 55 Gas introduction chamber 56 Exhaust chamber 57 Exhaust port 58 Reaction chamber 91 Gas inlet 92 Gas introduction chamber 93 Gas exhaust pipe 94 Gas exhaust port

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[Procedure amendment]

[Submission date] July 12, 1999 (1999.7.1)
2)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 5

[Correction method] Change

[Correction contents]

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G051 BG03 BG07 BH05 4K030 AA05 AA11 EA01 EA05 EA11 JA09 LA14 5F045 AA04 AB17 AC01 AC08 BB01 DP15 DQ06 EF13 EF20 EG02 EG06

Claims (13)

[Claims] A first flow passage having a flat and uniform height; and a second flow passage having an opening through which a fluid is introduced or led out and communicating with the first flow passage. The length of the first flow path in the flow direction is longer than the length of the second flow path in the same direction, and the height of the first flow path is lower than the height of the second flow path. A rectifier characterized in that: 2. The rectifier according to claim 1, wherein a pressure difference in the first flow path is larger than a pressure difference in the second flow path. 3. The first flow path is a tubular flow path, the second flow path is a rectangular chamber, and the second flow path is formed in the first flow path along a pipe axis direction. A parallel flow flowing toward the opening is formed, and a part or all of the parallel flow is bent in the second flow path to form a flow toward the opening. Rectifier as described. 4. The flow path of a fluid introduced from the opening in the second flow path, wherein the first flow path is a tubular flow path, the second flow path is a rectangular chamber. 3. The rectifier according to claim 1, wherein the flow is expanded by bending the entire flow, and the expanded flow becomes a parallel flow flowing along a pipe axis direction in the first flow path. 4. 5. The width of the first flow path in a direction orthogonal to the flow direction and the height direction is uniform along the flow direction,
The rectifier according to any one of claims 1 to 5, wherein the width of the second flow path in the same direction is uniform along the flow direction. 6. The first flow path and the second flow path are annular and communicate with each other in a radial direction, and a radial flow flowing in the radial direction is formed in the first flow path. The flow of the radial flow is bent toward the opening in the second flow path.
Or the rectifier of 2. 7. The first flow path and the second flow path are annular and communicate with each other in a radial direction, and a part or a part of a flow of a fluid introduced from the opening in the second flow path. 3. The rectifier according to claim 1, wherein the flow is expanded by being entirely bent, and the expanded flow becomes a radial flow flowing along the radial direction in the first flow path. 4. 8. The rectifier according to claim 1, wherein a plurality of openings are provided in said second flow path. 9. The apparatus according to claim 1, wherein a ratio of a height of said first flow path to a height of said second flow path is 1: 2 or more.
9. The rectifier according to any one of items 8 to 8. 10. An annular first flow passage having a flat and uniform height, and an opening through which a fluid is introduced or discharged, wherein the first flow passage and an outer peripheral surface or an inner peripheral surface of the flow passage are provided. An annular second flow path that is communicated with the first flow path, wherein the radial length of the first flow path is longer than the length of the second flow path in the same direction, A rectifier, wherein the height is lower than the height of the second flow path. 11. A rectifier according to any one of claims 1 to 10, and a reaction chamber connected to the first flow path provided in the rectifier, on a side opposite to the second flow path. A gas phase reactor, wherein a substantially uniform flow is formed in the reaction chamber. 12. A tubular conduit having a flat and uniform height, and a rectangular gas reservoir having an opening for introducing or discharging gas and connected to one end of the conduit. The length of the conduit is longer than the length of the gas reservoir, and the height of the conduit is lower than that of the gas reservoir. 13. An annular gas pipe having a flat and uniform height, an opening for introducing or discharging a fluid, and an annular gas connected to the pipe at an outer peripheral surface or an inner peripheral surface of the conduit. And a collecting chamber, wherein the radial length of the conduit is longer than the radial length of the gas collecting chamber, and the height of the conduit is higher than the height of the gas collecting chamber. A gas rectifier characterized by being low.