JPH11152572A - Gas expanding flow regulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely and uniformly spread the gas introduced from fine piping even in a reduced pressure state or even when a flow velocity is high by suppressing a back flow in spite of a lessened space. SOLUTION: This flow regulator has an introducing port 1 connected to the fine piping and a flat discharge port 3. The space between the introducing port and the discharge port comprises a flat passage 2. The height of the flat passage is uniform exclusive of ends and bent part 4 and, in addition, the shortest distances between the central point of the introducing port 1 on the flat passage and the arbitrary points of the discharge port are all equal within ±10%. In order to make the respective pressures of the introducing port 1 and the discharge port uniform, the velocities of flow are all required to be equal at the arbitrary shortest route between the introducing port 1 and the discharge port. Then, the velocities of flow of the gas discharged at all the points of the discharge port are made equal and uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to gas sizing and expansion, and more particularly, to chemical vapor deposition (CVD).
The present invention relates to the uniform distribution of gas in a gas introduction part and a gas distribution part to a reaction chamber of an apparatus.

[0002]

2. Description of the Related Art Metal-organic vapor phase epitaxy (MOVPE), which is one of the vapor-phase growth methods, has recently been used as a crystal growth method for compound semiconductors of semiconductor lasers. Fig. 8 is a schematic view showing a conventional reaction tube of a MOVPE crystal growth apparatus.
In the E crystal growth, an organic metal such as trimethylaluminum, trimethylgallium, and trimethylindium and a hydride such as arsine and phosphine are used as raw materials. By changing the type or concentration ratio of these raw materials, different compound semiconductor crystals can be grown. For example, when growing an AlGaAs compound semiconductor crystal, trimethylaluminum 201, trimethylgallium 202, and arsine 203 are used as raw materials. These raw materials are mixed in a carrier gas such as hydrogen or nitrogen, and the mixed gas 100 flows through a pipe 208. Piping 208
Connected to reaction tube 101. In the reaction chamber 101, the substrate 1
A susceptor 102 for supporting the substrate 03 and a substrate 103 are provided. In order to heat the susceptor 102 by high-frequency electromagnetic induction, a high-frequency coil 10 is provided outside the reaction chamber 101.
4 are provided. Cooling water 105 is supplied to cool the outer wall of the reaction chamber 101. The reaction chamber 101 is further connected to an exhaust mechanism 106 for exhausting gas. By adjusting the exhaust amount of the exhaust mechanism 106, the reaction chamber 10
1 can be changed. By heating the susceptor 102 and flowing the mixed gas 100 containing the raw material from the piping 208 upstream of the reaction chamber, the raw material is thermally decomposed on the substrate 103 and crystal growth starts.

[0003] Although the MOVPE growth has been described so far, not only the MOVPE growth but also a gas phase growth apparatus is generally configured such that a plurality of gases are mixed and the mixed gas is led to a reaction chamber through a pipe. . In the reaction chamber, the mixed gas flows over the entire heated substrate, the raw material is thermally decomposed, and the entire substrate is grown.

In order to make the crystal growth rate and crystal composition uniform over the entire substrate, it is necessary that the gas flow (flow velocity and gas components) be uniform on the substrate 103. In general, the cross-sectional area of the pipe 208 for introducing gas into the reaction chamber 101 is smaller than the area of the reaction chamber 101 or the substrate 103 where the growth is performed. Therefore, in order to make the gas flow uniform on the substrate 103, it is necessary to uniformly spread the gas flow from the pipe 208 to the substrate in the reaction chamber 101. As one of the methods, a shape in which a pipe is gradually widened like a horn is used (for example, Japanese Patent Application Laid-Open Nos. 62-061318 and 3-111571). FIG. 9 is a schematic diagram illustrating an example of the shape of the horn. The gas is guided to the inlet 1 through the gas inlet pipe 8, the gas is spread from the inlet 1 by the horn 204, and is exhausted from the outlet 3.
The reason for adopting the shape of gradually expanding the pipe in this way is that if the pipe is rapidly expanded, the gas flow will peel off from the wall, and the flow velocity will be slow near the wall, or in extreme cases, the backflow will occur near the wall, But there is a difference between the center and the periphery of the horn,
This is because crystal growth on the substrate becomes non-uniform.

[0005] However, it has already been a problem that the gas flow cannot be uniformly spread only by the simple horn shape. As a solution, a small exhaust port is provided on the horn wall to increase the flow velocity near the horn wall (Japanese Patent Laid-Open No. 62-061318). After exiting the horn, the gas passage is narrowed. (JP-A-63-134600), and a horn provided with an injection port for forming a flow for forcibly spreading gas at the base of the horn (JP-A-1-0861414). ), With fins inside the horn (Japanese Patent Laid-Open No. 1-3)
No. 15130), and a screen provided with a screen at the base of the horn for spreading gas (Japanese Patent Laid-Open No. 6-005525). As another method, a method of passing a plate having many small holes through it has also been proposed (Japanese Patent Application Laid-Open Nos. 1-047018, 1-081216, 1-081217, 7-050).
260, JP-A-6-216033). This method makes use of the effect that when a gas passes through a small hole, a differential pressure is generated so that the gas expands. There has also been proposed a method in which a plurality of inlets having a mechanism for controlling the flow velocity are provided instead of small holes to expand the gas (JP-A-62-229927, JP-A-4-33863).
No. 6). Further, a structure in which a horn is provided at each of a plurality of inlets has also been proposed (Japanese Patent Laid-Open No. 4-187594).
JP-A-5-291151).

[0006]

However, in the case of the conventional horn type, various devices have been proposed. However, in any of the devices, if the decompression state or the flow velocity is high, the horn shape must be lengthened. However, in extreme cases, there is a problem that the flow of gas cannot be sufficiently widened even if the length is increased. The same applies to the case of using a small hole.If the pressure is reduced or the flow rate is high, the hole must be made extremely small.On the contrary, if the hole is made small, the gas spreads but a backflow occurs on the upstream side of the plate. There was a problem that would. Another problem is that small holes must be produced with high accuracy. In the case of a plurality of inlets having a flow control mechanism, if the inlets are spread, a uniform flow is obtained, but there is a disadvantage that the flow control mechanism becomes enormous. Conversely, if the structure is such that the inlet is thinned, the flow control mechanism can be suppressed to a practical level, but there is a problem that the flow velocity in the thinned region is reduced and the uniformity is impaired.

SUMMARY OF THE INVENTION It is an object of the present invention to suppress backflow while saving space, and to evenly spread the flow of gas introduced from a thin pipe even when the pressure is reduced or the flow rate is high.

[0008]

According to a first aspect of the present invention relating to gas rectification expansion, a gas inlet connected to a pipe and a flat gas outlet directed in one direction are provided. Between the gas outlet and the gas outlet, and the height of the flat gas passage is uniform except for the ends and the bent portion of the passage, and the gas inlet of the gas inlet on the flat gas passage A gas expansion rectifier characterized in that the shortest distances between a central point and an arbitrary point of a gas outlet are all equal within ± 10%.

A gas expansion rectifier according to a second aspect of the present invention is characterized in that, based on the features of the first aspect, the gas inlet is located at an end of a flat gas passage.

The gas expansion rectifier according to the third aspect of the present invention has a gas inlet connected to a pipe and a flat gas outlet directed in one direction, and has a gas inlet and a gas outlet between the gas inlet and the gas outlet. Is formed by a flat gas passage, and obtained by connecting the center point of the gas inlet and an arbitrary point of the gas outlet on the flat gas passage in the shortest distance. The small displacement angle around the center point of the gas inlet corresponding to the small displacement in the direction is ±
It is characterized by being equal within 10%.

According to a fourth aspect of the present invention, based on the features of the third aspect, the gas inlet is located at an end of the flat gas passage.

A fifth aspect of the present invention provides a gas expansion rectifier which satisfies the features of the first and third aspects simultaneously.

According to a sixth aspect of the present invention, based on the features of the fifth aspect, the gas inlet is located at an end of a flat gas passage.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings together with the principle of operation of each invention.

FIG. 1A is a front view showing an embodiment of the first invention, FIG. 1B is an elevation view showing the first invention, and FIG. It is a bottom view which shows invention. FIGS. 2 to 4 show one embodiment of the second to fourth inventions, respectively. The gas expansion rectifier of the present invention is characterized in that all of the first to sixth inventions include an inlet 1, a flat passage 2, and an outlet 3 to which a pipe for gas introduction is connected. In the first and second inventions, the flat passage 2 has a uniform height except for the ends and the bent portion 4 of the passage, and has a center point 5 of the inlet on the flat passage 2 and an outlet. Shortest path 7 to any point 6
Are all equal. An example of such a flat passage 2 is a parabolic shape shown in FIG. The center point 5 of the inlet is located at the focal point of a parabola which is the shape of the bent part 4 of the passage in FIG.
In that case, the shortest path 7 has the same distance regardless of the position of the arbitrary point 6 of the outlet at any position of the outlet. With such a configuration, the gas introduced from the gas introduction pipe 8 receives resistance from the wall surface in the flat passage 2, and a slight pressure drop (differential pressure) occurs from upstream to downstream. The sum (integrated) of this pressure drop from the inlet 1 to the outlet 3 along the gas flow corresponds to the pressure difference between the inlet 1 and the outlet 3. The gas passes through the shortest path 7 to minimize the pressure difference between the inlet 1 and the outlet 3 as much as possible, and spreads as much as possible to reduce the pressure difference by reducing the flow velocity. Furthermore, since the inlet 1 and the outlet 3 have a wider space on the opposite side of the flat passage 2 than the flat passage 2, the pressure at each point of the inlet 1 and the outlet 3 is uniform. (Same pressure) (accurately, there may be a pressure difference sufficiently smaller than the pressure difference generated in the flat passage 2). Therefore, even if the gas flows out from any point of the outlet 3, the gas flows so as to satisfy the condition that the pressure difference between the inlet 1 and the outlet 3 is equal. In general, the magnitude of the pressure drop when flowing through a passage having a constant height for a fixed distance depends only on the flow velocity. In the present invention, the shortest distances between the center point 5 of the inlet and any point 6 of the outlet are all equal, and the height is constant. Therefore, in order to satisfy the above-mentioned condition that the pressure difference between the inlet 1 and the arbitrary point 6 at the outlet is equal,
What is necessary is to flow at a uniform flow velocity along an equidistant shortest path 7 connecting the shortest distance between the center point 5 of the inlet and any point 6 of the outlet.
Then, the flow velocity at all points of the outlet becomes equal, and it becomes possible to flow gas at a uniform flow velocity into the reaction chamber.

Further, the first and second inventions have a feature that the gas flows from the inlet 1 to the outlet 3 at the same time because the height and the distance are the same regardless of the route from the inlet 1 to the outlet 3. Have. That is, at the time of gas switching, the gas components at each point of the outlet are simultaneously switched. When there is no such gas synchronism, diffusion occurs due to the difference in concentration of gas components, and the gas components after switching are mixed in the gas before switching, and the gas components before switching in the gas after switching. And steep gas switching is hindered.

Next, the relationship between the first invention and the second invention will be described. In the first invention, since the inlet 1 is not at the end of the flat passage 2, the gas introduced from the inlet 1 may flow slightly but in the opposite direction. This flow is different from the so-called reverse flow, which forms a vortex, and in that sense, there is no reverse flow. However, the flow in the opposite direction will cause stagnation 9 where it hits the end of the flat passage, and when the components of the gas introduced are switched at some point, the gas discharged from the outlet will stagnate for some time. Steep gas switching is impeded. The second invention eliminates this disadvantage. FIG. 2A shows the second
FIG. 2B is an elevation view showing the second invention, and FIG. 2C is a bottom view showing the second invention. Since the inlet is at the end of the flat passage, all gas introduced from the inlet flows out toward the outlet. Since no stagnation occurs, the gas is rapidly switched.

FIG. 3A is a front view showing one embodiment of the third invention, FIG. 3B is an elevation view showing the third invention, and FIG. It is a bottom view which shows invention. The flat passage 2 according to the third and fourth aspects of the present invention is obtained by connecting the center point 5 of the inlet and any point 6 of the outlet on the flat passage 2 with the shortest distance. It is characterized in that the small displacement angle Δθ11 around the center point 5 of the inlet corresponding to the small displacement angle Δx10 in the flat direction of any point 6 is equal at any point of the outlet 3. An example of such a flat passage 2 is a curved shape shown in FIG. If the x-axis and the y-axis are provided as shown in FIG. 3, the width 12 of the outlet is W, and the distance 13 between the center 5 of the inlet and the x-axis is F, the point T (x , Y)

[0019]

(Equation 1) It is expressed by the relationship. With such a configuration, the gas introduced from the gas introduction pipe 8 receives resistance from the wall surface in the flat passage 2, and a slight pressure drop (differential pressure) occurs from upstream to downstream. Gas is supplied to inlet 1 and outlet 3
Through the shortest path 7 so as to minimize the pressure difference, and expand as much as possible to reduce the pressure difference by reducing the flow velocity. When the gas spreads in the flat passage 2 at the inlet 1 by the latter action, the gas flows so as to be distributed evenly with respect to the angle θ. In the present invention, as described above, the point of the outlet 3 in the flat direction obtained when the center point 5 of the inlet and the arbitrary point 6 of the outlet are connected on the flat passage 2 at the shortest distance. The small displacement angle Δθ11 around the center point 5 of the inlet corresponding to the displacement Δx10 is equal at any point of the outlet 3. Therefore, the gas evenly distributed with respect to the angle θ at the inlet 1 is evenly distributed in the flat direction also at the outlet 3 if the gas flows through the shortest path 7 between the inlet 1 and the outlet 3. Will be. Then, the flow velocity at each point of the outlet 3 becomes equal, and it becomes possible to flow the gas at a uniform flow velocity into the reaction chamber.

FIG. 4A is a front view showing an embodiment of the fourth invention, FIG. 4B is an elevation view showing the fourth invention, and FIG. It is a bottom view which shows invention. Similarly to the improvement of the second invention with respect to the first invention, the improvement of the fourth invention is realized with respect to the third invention. That is, the fourth invention solves the disadvantage of the stagnation 9 of the third invention. The operation is the same as that described in the description of the second invention with respect to the first.

A fifth aspect of the present invention is such that both the first and third aspects of the invention are established, and inherits the features of both aspects. The first invention is effective or the third invention is effective depending on the nature of gas and flat piping, but it is not necessary to ask which invention is effective if the fifth invention is effective. Therefore, there is an advantage that the combination of components of the mixed gas is not restricted.

Similar to the improvement of the second invention with respect to the first invention, the improvement of the sixth invention holds for the fifth invention. That is, the sixth invention solves the stagnation disadvantage of the fifth invention.

The operation is the same as that described in the description of the second invention with respect to the first invention.

In the first to sixth aspects of the present invention, even if the shortest distance 7 or the small displacement angle Δθ11 is not strictly equal, since the gas is viscous, the surrounding gas has the same flow rate. Therefore, the above effects are exhibited. From experience, no significant abnormality was found in the uniformity even though it deviated by about ± 10%.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited to these embodiments, and can be appropriately modified within the scope of the claims. Embodiment 1 FIG. 1A is a front view showing an embodiment of the first invention, FIG. 1B is an elevation view showing the first invention, and FIG.
FIG. 2 is a bottom view showing the first invention. The gas expansion rectifier of the present invention comprises an inlet 1, a flat passage 2, and an outlet 3 in all of the first to sixth inventions. As a material for forming the flat passage 2, a material such as quartz glass or stainless steel which does not react with a gas flowing through the passage and does not emit impurities is desirable for crystal growth. When the degree of flatness is represented by the ratio of the width to the height of the passage, the effect of uniformly expanding the gas becomes remarkable at 10: 1 or more. However, this result is obtained when hydrogen gas is used. The present invention is not limited to this value, as this ratio depends on the type of gas. If the flat passage 2 has a temperature distribution, the viscosity corresponding to the resistance of the gas flow changes depending on the place, so that it is difficult to uniformly spread the gas. for that reason,
It is desirable to control the temperature distribution to be uniform.

Embodiment 2 An example in which the gas expansion rectifier of the present invention as described in Embodiment 1 is applied to a MOVPE crystal growth apparatus which is one example of vapor phase growth will be described.

FIG. 5 is a schematic diagram showing a reaction tube of a MOVPE crystal growth apparatus equipped with the gas expansion rectifier of the second invention. 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, trimethylaluminum, trimethylgallium, and arsine are used as raw materials. These raw materials are mixed in a carrier gas such as hydrogen or nitrogen, and the mixed gas 100 is supplied to a pipe. This mixed gas 100 is guided to the inlet 1 of the gas expansion rectifier of the present invention by the gas introduction pipe 8. The outlet 3 of the gas expansion rectifier is connected to the reaction chamber 101 where the growth takes place. The reaction chamber 101 is preferably rectangular so as to easily maintain the effect of the gas expansion rectifier of the present invention. In the reaction chamber 101, a susceptor 102 for supporting a substrate
Then, a mechanism for heating the susceptor and the substrate 013 are installed. As a material of the susceptor 102, a material such as carbon or molybdenum that is stable with respect to a carrier gas or a raw material even at a high temperature is desirable. Mechanisms for heating the susceptor include electromagnetic induction heating using high frequency, lamp heating using infrared light, and resistance heating using electric current. FIG. 5 shows an example of electromagnetic induction heating, in which a high-frequency coil 104 is provided. Cooling water 105 is supplied to cool the outer wall of the reaction chamber 101. The reaction chamber 101 is further connected to an exhaust mechanism 106 for exhausting gas. By adjusting the exhaust amount of the exhaust mechanism 106, the reaction chamber 101
Pressure can be changed. Since the gas expansion rectifier of the present invention operates not only at normal pressure but also at reduced pressure, there is an advantage that the pressure application range is wide and the growth conditions are not limited.

In such a configuration, the raw material gas passes through the gas introduction pipe 8, is flat and uniformly expanded by the gas expansion rectifier of the present invention, and is introduced into the reaction chamber 101. In the reaction chamber 101, the susceptor 102 heated by the mechanism for heating the susceptor 102 supports the substrate 103 and heats the substrate 103. On the heated substrate 103, the source gas is thermally decomposed and the substrate 1
03 is grown on the substrate. Since the flow velocity is uniform, the crystal growth rate is uniform in the direction perpendicular to the flow.

Actually, a high frequency is supplied to the high frequency coil 104 and the temperature of the susceptor 102 is set to 700 by electromagnetic induction heating.
° C, the pressure in the reaction chamber 101 is 70 Torr, and a mixed gas 100 of trimethylaluminum, trimethylgallium, and arsine is supplied to the reaction chamber 101 using hydrogen as a carrier gas.
To grow crystals. FIG. 6 is a graph showing the distribution of the growth rate on the substrate. The horizontal axis represents the position on the substrate 103 in the direction perpendicular to the flow, and the vertical axis represents the growth rate of AlGaAs. When the gas expansion rectifier of the present invention is used, compared with the case where a conventional horn-shaped gas expansion rectifier is used,
The uniformity of the growth rate was remarkably improved.

Embodiment 3 In some cases, an intermediate reaction occurs between the raw materials before the raw material gas reaches the reaction chamber. For example, there is a combination of trimethylindium and phosphine. In order to prevent this intermediate reaction, it is conceivable to adopt a structure in which easily reactable raw material gases are separated immediately before the reaction chamber so as to be mixed immediately before. This can be realized by increasing the number of gas introduction pipes 8, further increasing the number of gas expansion rectifiers of the present invention, and disposing the outlets 3 of the plurality of gas expansion rectifiers close to each other. FIG. 7 is an elevational view showing a structure in which two gas expansion rectifiers of the second invention are closely attached, which is one embodiment of the present invention.

Although MOVPE growth has been described as an example, it goes without saying that the invention can be applied to general vapor phase growth.

By providing a uniform dividing plate at the outlet of the gas expansion rectifier of the present invention and connecting it to a pipe for each of the divided areas, the gas distributor can be used as a gas distributor for dividing gas at an equal flow rate.

By providing a structure in which the discharge port of the gas expansion rectifier of the present invention is closed with a plate having holes evenly, it becomes possible to blow out a uniform gas from each hole. As one application example, a bubbling gas outlet at the time of bubbling an organometallic raw material with a carrier gas can be considered.

In the configuration in which the outlet of the gas expansion rectifier of the present invention is opened to the atmosphere, when a nitrogen gas is introduced as another application example, a substrate having a wide area can be blown uniformly.

Although the present invention has been described assuming a gas, the present invention can be applied to a liquid if a flat passage having viscosity is formed.

Although the present invention has been described on the assumption that the gas is spread evenly, it is also possible to suck the gas uniformly by flowing the gas in reverse.

[0037]

According to the present invention, the present invention is applied to a vapor phase growth apparatus and, in particular, to MOVPE.
By using the gas introduction part into the reaction chamber of the apparatus, it is possible to realize uniform crystal growth in the direction perpendicular to the flow.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of the first present invention, wherein (a)
Is a front view, (b) is an elevation view, and (c) is a bottom view.

FIG. 2 is a view showing one embodiment of the second present invention, wherein (a)
Is a front view, (b) is an elevation view, and (c) is a bottom view.

FIG. 3 is a drawing showing one embodiment of the third invention, wherein (a)
Is a front view, (b) is an elevation view, and (c) is a bottom view.

FIG. 4 is a view showing one embodiment of the fourth invention, wherein (a)
Is a front view, (b) is an elevation view, and (c) is a bottom view.

FIG. 5 shows a M mounted with the gas expansion rectifier of the second invention.
It is a schematic diagram which shows the reaction tube of an OVPE crystal growth apparatus.

FIG. 6 is a graph showing a distribution of a growth rate on a substrate.

FIG. 7 is an elevational view showing a structure in which two gas expansion rectifiers of the second invention are adhered to each other.

FIG. 8 is a schematic diagram showing a conventional reaction tube of the MOVPE crystal growth apparatus.

FIG. 9 is a schematic view showing an example of a conventional horn-shaped gas expanding rectifier.

[Explanation of symbols]

Reference Signs List 1 gas inlet 2 flat gas passage 3 gas outlet 4 bent portion of gas passage 5 center point of gas inlet 6 arbitrary point of gas outlet 7 center of gas inlet in flat gas passage of gas expansion rectifier Shortest path between a point and an arbitrary point of the gas outlet 8 Gas inlet pipe 9 Stagnation 10 Small displacement Δx 11 in the flat direction of the gas outlet 11 Small displacement angle Δθ around the center point of the gas inlet 12 Gas outlet Width W 13 Distance between the center of the gas inlet and the x-axis F 100 Mixed gas 101 Reaction chamber 102 Susceptor 103 Substrate 104 High frequency coil 105 Cooling water 106 Exhaust mechanism 200 Hydrogen 201 Hydrogen-based trimethylaluminum 202 Hydrogen-based trimethylgallium 203 Hydrogen-based arsine 204 Horn 208 Piping

Claims (6)

[Claims] A gas inlet connected to the pipe, a flat gas outlet facing in one direction, and a flat gas passage between the gas inlet and the gas outlet; In addition, the height of the flat gas passage is uniform except at the ends and bent portions of the passage, and the shortest distance between the center point of the gas inlet and any point of the gas outlet on the flat gas passage is all Gas expansion rectifier characterized by being equal within ± 10%. 2. The gas expansion rectifier according to claim 1, wherein the gas inlet is at an end of the flat gas passage. 3. A gas inlet connected to a pipe, and a flat gas outlet facing in one direction, wherein a flat gas passage is formed between the gas inlet and the gas outlet. In addition, when the center point of the gas inlet and any point of the gas outlet are connected in the shortest distance on the flat gas passage, the gas introduction corresponding to the minute displacement of the point of the gas outlet in the flat direction is obtained. A gas expansion rectifier characterized in that the small displacement angle around the center point of the mouth is equal within ± 10% at any point of the gas outlet. 4. The gas expansion rectifier according to claim 3, wherein the gas inlet is at an end of the flat gas passage. 5. It has a gas inlet connected to a pipe, and a flat gas outlet facing one direction, and a flat gas passage is formed between the gas inlet and the gas outlet. In addition, the height of the flat gas passage is uniform except at the ends and bent portions of the passage, and the shortest distance between the center point of the gas inlet and any point of the gas outlet on the flat gas passage is all It is equal to within ± 10%, and is obtained when the center point of the gas inlet and any point of the gas outlet are connected in the shortest distance on the flat gas passage, in the flat direction of the point of the gas outlet. A gas expansion rectifier characterized in that a minute displacement angle around a central point of a gas inlet corresponding to a minute displacement is equal to within ± 10% at any point of a gas outlet. 6. The gas expansion rectifier according to claim 5, wherein the gas inlet is at an end of the flat gas passage.