JP4444389B2 - Exhaust gas purification method and purification apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a purification method and a purification apparatus for exhaust gas discharged from a semiconductor manufacturing apparatus, and more particularly, to a method and a purification apparatus for purifying exhaust gas discharged from a gallium nitride film semiconductor manufacturing apparatus that uses a large amount of ammonia. .
[0002]
[Prior art]
In recent years, a demand for a gallium nitride film semiconductor, which is a compound semiconductor, has been rapidly increasing as a light emitting element and a light receiving element mainly in the field of optical communication. As a manufacturing method of a gallium nitride film semiconductor, an MOCVD method in which an organic metal gas typified by trimethylgallium is used as a gallium source and vapor-phase growth is performed by a reaction of this with ammonia gas, and hydrogen chloride is added to the metal gallium. An HVPE method (hydride VPE method) is well known in which a gallium chloride (GaCl) gas generated by flowing a gas is used as a gallium source and vapor-phase growth is performed by a reaction between this gas and ammonia gas. All of these methods require a large amount of ammonia gas because of the low efficiency of nitrogen uptake from ammonia gas. In particular, the MOCVD method uses a large amount of ammonia gas, and a large amount of unreacted ammonia gas is discharged after the film formation process.
[0003]
The HVPE method synthesizes gallium chloride (GaCl) by a reaction between metal gallium and hydrogen chloride at a first temperature, and a substrate set in advance by a reaction between the gallium chloride and ammonia at a second temperature. A gallium nitride film is grown thereon. The reaction furnace is a hot wall type and is normally grown at normal pressure.
The HVPE method uses less ammonia gas than the MOCVD method, but discharges a small amount of hydrogen chloride gas and a large amount of ammonium chloride powder simultaneously with a large amount of unreacted ammonia gas. Since ammonia gas and hydrogen chloride gas are harmful gases, it is necessary to purify the exhaust gas containing these toxic gases discharged from the semiconductor manufacturing apparatus before releasing them into the atmosphere.
[0004]
As a purification method of ammonia gas in the field of chemical industry, generally a method using an aqueous solution of water or an acid as an absorbing solution, or a wet absorption method using an aqueous solution of a copper salt or the like forming a complex salt with ammonia as an absorbing solution has been used for a long time. Well known and put into practical use. Similarly, as a method for purifying hydrogen chloride gas, a wet absorption method using an aqueous solution of water or alkali has been known for a long time and has been put into practical use.
In the field of semiconductor manufacturing industry, if a purification device using a wet absorption method is used as a primary purification device immediately after an atmospheric pressure type semiconductor manufacturing device, the product will be adversely affected by the reverse diffusion of moisture from the absorbing liquid to the semiconductor manufacturing device. Thus, such a method has hardly been put into practical use regardless of the type of exhaust gas to be purified.
[0005]
For this reason, in the field of the semiconductor manufacturing industry, the wet absorption method is put into practical use because the gas flow path is mechanically insulated by installing a vacuum pump or the like between the semiconductor manufacturing apparatus and the purification apparatus. This is the case of the primary purification immediately after the reduced pressure semiconductor manufacturing apparatus so that the back diffusion of moisture from the absorbing liquid does not occur. In addition, the wet absorption method is used in the case of a final purification apparatus that collects exhaust gas after the primary purification is completed by a purification method other than the wet absorption method immediately after various semiconductor manufacturing apparatuses. In the case of such an exhaust gas final purification device, exhaust air from various semiconductor manufacturing devices is gathered, and therefore, a device that has a large air volume and that can be easily scaled up, such as a wet absorption method, is preferable.
[0006]
On the other hand, in the field of semiconductor manufacturing industry, there are many semiconductor manufacturing apparatuses that use ammonia gas. However, since the amount of ammonia gas used is relatively small except for the apparatus for manufacturing a gallium nitride film semiconductor, various methods can be used as the primary purification method. Examples of such a primary purification method include a dry adsorption method in which exhaust gas is introduced into a container filled with an adsorbent such as activated carbon and purified by a physical adsorption action, and a container filled with a chemical having chemical reactivity with ammonia is exhausted. The dry reaction method that purifies by chemical reaction by introducing hydrogen, the combustion method that converts the ammonia gas into nitrogen and moisture and treats it by introducing the exhaust gas to be purified into the combustion flame using hydrogen gas or propane gas as fuel It is done.
[0007]
Among the gallium nitride film semiconductor manufacturing apparatuses, for primary purification of exhaust gas from the MOCVD method, a catalytic decomposition method that decomposes ammonia gas into nitrogen gas and hydrogen gas by introducing exhaust gas onto the catalyst under heating, and the dry process A combination of reaction methods is preferably used.
The exhaust gas from the MOCVD method includes a large amount of ammonia gas, nitrogen gas, hydrogen gas, and a very small amount of organometallic gas such as trimethylgallium. Of these, nitrogen gas and hydrogen gas do not need to be purified, and an extremely small amount of organometallic gas such as trimethylgallium can be purified by a known dry reaction method. For this reason, in order to prevent poisoning of the decomposition catalyst by the organometallic gas, the organometallic gas is first purified by a dry reaction method, and then ammonia gas is decomposed into nitrogen gas and hydrogen gas on the heated catalyst. Thereafter, a method of purifying a small amount of ammonia gas remaining undecomposed by chemical equilibrium by a known dry reaction method is known.
[0008]
[Problems to be solved by the invention]
Among the gallium nitride film semiconductor manufacturing equipment, the exhaust gas from the HVPE method includes about 1/10 amount of ammonia gas and nitrogen gas, hydrogen gas and a very small amount of hydrogen chloride gas, gallium chloride gas and a large amount of ammonium chloride of the MOCVD method. Of powder. Due to these characteristics, in order to support primary purification with a combination of the catalytic decomposition method and the dry reaction method as described above, the construction cost of the purification device is large for a small amount of ammonia gas. It is not appropriate because of the large installation space.
Also, hydrogen chloride gas, gallium chloride gas and a large amount of ammonium chloride powder cause poisoning of the decomposition catalyst, so it is necessary to purify in advance upstream of the decomposition cylinder. Therefore, in general, a filter is first installed to remove ammonium chloride powder, and then hydrogen chloride gas and the like are purified by a dry purification cylinder. In this case, since the amount of ammonium chloride powder is fine and large, there is a problem that the treatment is difficult even if a filter or the like is used. Moreover, when not installing a filter, there exists a possibility of closing a dry purification cylinder.
[0009]
In the case of the combustion type purification method, there is a possibility that ammonium chloride powder may block the combustion nozzle, so that the powder must be processed in advance using a filter or the like, which is inconvenient. In this case, since about half of the amount of ammonia to be processed becomes NOx, there is a risk of environmental pollution.
Moreover, since the HVPE method uses an atmospheric pressure type semiconductor manufacturing apparatus in the wet absorption method, there is a concern that the product may be adversely affected by the reverse diffusion of moisture from the absorption liquid.
[0010]
For the above reasons, the dry method is currently employed as the primary purification method by the HVPE method. The dry reaction method has excellent characteristics that it has high purification efficiency, can completely remove ammonia gas, is easy to handle, and requires a small installation space. Further, there is an advantage that hydrogen chloride gas and gallium chloride gas can be removed simultaneously by combining the chemicals to be filled.
[0011]
However, even in the dry reaction method, the powder of ammonium chloride is deposited between the chemicals and gradually increases the pressure loss. Therefore, there is a problem that the pressure loss increases before the full capacity of the chemicals is used up, so that it becomes unusable. Moreover, since the chemical | medical agent of a dry-type reaction method is comparatively expensive, the running cost of a process is high, and the chemical | medical agent after a process comes out in large quantities as an industrial waste.
[0012]
In view of the above points, an object of the present invention is to stably and efficiently treat exhaust gas particularly from the HVPE method in a gallium nitride film semiconductor manufacturing apparatus. Specifically, the installation cost of the exhaust gas purification device is small, the construction cost is low, and the running cost of the exhaust gas treatment does not adversely affect the product due to the back diffusion of moisture from the exhaust gas purification device to the semiconductor manufacturing device. It is to develop a purification method and a purification device for exhaust gas having a low level. In addition, the object of the present invention is that the exhaust gas purification device is easy to handle, and gallium chloride gas can be completely removed simultaneously with ammonia gas and hydrogen chloride gas, and pressure loss due to ammonium chloride powder does not occur. Another object of the present invention is to provide an exhaust gas purification method and a purification device capable of reducing industrial waste without causing environmental pollution due to NOx or the like.
[0013]
[Means for Solving the Problems]
As a result of intensive studies on methods for solving these problems, the present inventors have found that the cross-sectional area and length of the pipe connecting the gallium nitride film semiconductor manufacturing apparatus and the wet absorption method exhaust gas purification apparatus and the gas in the pipe It has been found that by specifying the relationship between the flow rates, it is possible to prevent an increase in pressure loss due to the adhesion of ammonium chloride powder in the pipe and to completely prevent the back diffusion of moisture from the absorption liquid of the purifier. Further, it has been found that by using hydrochloric acid or an aqueous solution of acid having a weaker acidity than hydrochloric acid as the absorbing solution, it is possible to dissolve and remove the gallium chloride powder contained in a trace amount and the ammonium chloride powder contained in a large amount in the exhaust gas. It was.
As a result, troubles in the absorption liquid circulation system due to crystal precipitation do not occur in the piping connecting the semiconductor manufacturing apparatus and the exhaust gas purification apparatus, and a large amount of ammonia gas can be absorbed, and further from the absorption liquid. It has been found that the amount of desorption of acidic gases such as ammonia gas and hydrogen chloride gas can be suppressed to an extremely low level.
[0014]
Furthermore, in order to remove acidic gases such as ammonia gas and hydrogen chloride gas that are desorbed from the absorption liquid, an exhaust gas purification apparatus of a wet absorption method using water as an absorption liquid is provided after the purification apparatus, or a mist separator is used. The present invention was completed by finding that complete purification can be achieved by additionally introducing a dry gas as necessary to prevent moisture condensation and providing a known dry purification device.
[0015]
That is, the present invention relates to an apparatus for manufacturing a gallium nitride film semiconductor in which a gallium chloride (GaCl) gas generated by flowing hydrogen chloride gas through metal gallium is used as a gallium source and vapor-phase grown by reaction with ammonia. In the wet absorption method exhaust gas purification method for treating the exhaust gas, the relationship between the pipe connecting the production apparatus and the wet absorption method exhaust gas purification device and the exhaust gas flow rate in the pipe is expressed by the cross-sectional area (cm ² ) of the pipe. An exhaust gas purification method characterized in that a product of a value obtained by dividing an exhaust gas flow rate (cm ³ / sec) and a length (cm) of the pipe is in a range of 100 to 25000.
[0016]
The present invention also relates to an apparatus for manufacturing a gallium nitride film semiconductor, in which a gallium chloride (GaCl) gas generated by flowing hydrogen chloride gas through metal gallium is used as a gallium source and vapor-phase grown by reaction with ammonia to form a film. In the wet absorption method exhaust gas purification device for purifying exhaust gas, the wet absorption method exhaust gas purification device is a pipe connecting this and the above gallium nitride film semiconductor manufacturing apparatus, and its cross-sectional area (cm ² ) The exhaust gas purifying apparatus is characterized in that it has a pipe whose product of the value obtained by dividing the exhaust gas flow rate (cm ³ / sec) and the length (cm) of the pipe is in the range of 100 to 25000.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is applied to a method and a purification apparatus for purifying exhaust gas from a semiconductor manufacturing apparatus. More specifically, the present invention is applied to a method and a purification apparatus for purifying exhaust gas containing a large amount of ammonia gas discharged from a gallium nitride film semiconductor manufacturing apparatus.
[0018]
The present invention relates to a pipe connecting the gallium nitride film semiconductor manufacturing apparatus and the wet absorption method exhaust gas purification apparatus by the HVPE method or the like and the gas flow rate, and the gas flow rate (cm ³ / sec) with the pipe cross-sectional area (cm ² ). The product of the value obtained by subtracting 1 and the length (cm) of the pipe is in the range of 100 to 25000, preferably 200 to 5000, and more preferably 500 to 2000. Here, pipe diameter is determined in accordance with the gas flow, usually the 20cm from 1, 15cm preferably from 2, more preferably from 10cm 3. The length of the pipe is appropriately determined depending on the installation position of the reaction furnace and the purification apparatus of the semiconductor manufacturing apparatus. The gas flow rate (cm ³ / sec) is determined by the cross-sectional area of the pipe (cm ² ). Is set so that the product of the value obtained by dividing the value by the length of the pipe (cm) is in the range of 100 to 25000.
[0019]
Here, when the gas flow rate is too low to satisfy the range of 100 to 25000, nitrogen gas or the like can be additionally introduced to optimize the conditions.
If the product of the value obtained by dividing the gas flow rate (cm ³ / sec) by the cross-sectional area of the pipe (cm ² ) and the length of the pipe (cm) is smaller than 100, there is a disadvantage that back diffusion of moisture occurs. When it is larger than 25000, there is a disadvantage that the pressure loss becomes large. If the equivalent diameter of the pipe is smaller than 1 cm, clogging in the pipe due to the adhesion of ammonium chloride powder may cause an increase in pressure loss. If the equivalent diameter is larger than 20 cm, the gas flow is not preferable. It becomes unstable and may cause back diffusion of moisture, which is not preferable.
[0020]
In the present invention, as the kind of acid used in the ammonia absorption liquid in the wet absorption exhaust gas purification apparatus, hydrochloric acid or an acid having a lower acidity than hydrochloric acid, such as phosphoric acid or acetic acid, can be used. Among these, it is preferable to use an aqueous solution of hydrochloric acid from the viewpoints of price, solubility of salts, and treatment of the absorbent after exhaust gas purification. Although there is no special restriction | limiting in the density | concentration of the acid in an absorption liquid, since the absorption capacity | capacitance of ammonia gas increases so that a density | concentration is high, it is advantageous.
[0021]
However, in the ammonia gas absorption liquid, in addition to the ammonium salt produced by the absorption of ammonia gas, the amount of ammonium chloride powder flowing from the semiconductor manufacturing equipment increases with time, and eventually the ammonium chloride and ammonium salt dissolve. The limit will be exceeded. As a result, troubles such as clogging due to crystal precipitation are caused. Therefore, the concentration of the acid used in the absorbing solution is usually preferably 15% by weight or less. If an acid that is more acidic than hydrochloric acid is used as the absorbent, the ammonium chloride powder into which the strong acid flows may be decomposed to generate hydrogen chloride gas, increasing the burden on the subsequent dry purification device. There are things to do.
[0022]
In the present invention, a wet absorption method exhaust gas purification device using water as an absorption liquid is further provided at the subsequent stage of the wet absorption method purification device, or by additionally introducing a dry gas by a mist separator and as necessary. By introducing into a known dry purification device after preventing moisture condensation, the exhaust gas from the gallium nitride film semiconductor manufacturing device can be stably and efficiently purified.
[0023]
In addition to being used for purification of exhaust gas from the HVPE furnace, this system is not a mass production furnace, but can also be applied to purification of exhaust gas from a small MOCVD furnace that consumes a large amount of ammonia gas. In that case, it is preferable to install a purification apparatus by a dry reaction method or a dry adsorption method in order to remove organic metals and the like before the wet absorption method purification apparatus.
[0024]
【Example】
The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples.
Example 1
(Semiconductor manufacturing equipment and exhaust gas purification equipment)
A gallium nitride film semiconductor manufacturing apparatus and a wet absorption method purification apparatus using an HVPE furnace as shown in FIG. 1 were manufactured. The HVPE furnace has a mixed gas supply pipe 3 of ammonia and hydrogen, a supply pipe 3 'of hydrogen chloride and hydrogen, an exhaust gas outlet 4, a boat 5 containing metal gallium, and a substrate 6 placed on the susceptor 7. A quartz reaction furnace 1 equipped with a heater 2 was used. However, neither the mist separator 17 in the rear stage, the dry purification cylinder 21 nor the supply of nitrogen gas was performed.
[0025]
The wet absorption method purifying device 9 includes four layers of laminated filters 14 (Saran Rock Filter, manufactured by Asahi Kasei Co., Ltd.) having a thickness of 50 mm on an absorption tube 10 having a square square tube whose inner side is 140 mm in length. The absorption liquid 12 made of an aqueous solution of hydrogen chloride is sprayed and absorbed from the upper part of the laminated filter through the spray nozzle 11 via the circulation pump 13.
Further, the exhaust gas outlet 4 and the wet absorption purification device 9 were connected by a stainless steel pipe 8 having an inner diameter of 4.53 cm and a length of 150 cm.
[0026]
(Exhaust gas purification test)
GaN was grown on the sapphire substrate as follows.
In the HVPE furnace shown in FIG. 1, the boat 5 containing Ga metal is always kept at 800 ° C. or more and 1000 ° C. or less, and the vicinity of the set position of the sapphire substrate 6 is 400 to 600 ° C. during the growth of the low temperature buffer layer. And maintained at 800 to 1100 ° C. during the subsequent epitaxial growth.
[0027]
The growth procedure was performed as follows. The sapphire substrate 6 was set in a reaction furnace and then cleaned at 1050 ° C. in a hydrogen atmosphere. Next, the sapphire substrate is 550 ° C., hydrogen chloride gas is supplied at a flow rate of 5 sccm (standard cubic centimeter per minute), and ammonia is supplied at a flow rate of 0.5 slm (standard liter per minute). A low temperature buffer layer was grown by flowing at a total flow rate of about 5 slm for about 20 minutes. Thereafter, the vicinity of the sapphire substrate 6 is heated to a growth temperature of 1020 ° C., and hydrogen chloride gas is supplied at a flow rate of 10 sccm and ammonia gas is supplied at a flow rate of 1 slm together with a hydrogen carrier for about 20 minutes at a total flow rate of 5 slm, thereby increasing the thickness on the sapphire substrate. A GaN epitaxial growth layer having a thickness of about 10 μm was obtained.
Such a growth operation was repeated 5 times.
During this time, in the wet absorption purification device 9, the exhaust gas from the HVPE furnace was purified by circulating a 2.3 mol / l hydrogen chloride aqueous solution at a flow rate of 6 L / m (liter per minute) at room temperature.
[0028]
As a result, no clogging or the like occurred in the piping between the exhaust gas outlet and the wet absorption method purification apparatus, and a smooth growth operation was performed. Moreover, the pressure difference between the reactor and the wet absorption method purification apparatus outlet was always 4 mmH ₂ O, and no increase in pressure loss was observed.
When the exhaust gas discharged from the wet absorption method purification device was analyzed with an ammonia detector tube (manufactured by Gastec Co., Ltd., 3La type, detection sensitivity 2.5 to 250 ppm), the ammonia content was below the detection limit. . Similarly, the concentration of hydrogen chloride in the exhaust gas was measured with a detector tube (manufactured by Gastec Corporation, 14L type, detection sensitivity of 1 to 20 ppm) and found to be 3 ppm or less.
[0029]
In this case, the product of the value obtained by dividing the exhaust gas flow rate (cm ³ / sec) by the cross-sectional area (cm ² ) of the pipe and the length (cm) of the pipe was 776, which was in the range of 100 to 25,000.
Moreover, in order to investigate the influence on the grown GaN epitaxial layer by the back diffusion of water vapor from the wet absorption method purification apparatus to the reactor, the characteristics of the grown GaN epitaxial layer were evaluated. As a result, the electrical properties were a carrier concentration of 2.0E17 / cm ² and a carrier mobility of 420 cm ² / Vs. Further, when photoluminescence was measured, strong band edge light emission was observed at 357 nm at 4.2 K, and no light emission was observed in the long wavelength region, indicating good characteristics.
[0030]
(Example 2)
In Example 1, the pipe connecting the reactor and the wet absorption method purification apparatus is changed to an inner diameter of 7.31 cm and a length of 150 cm, and a dry purification agent mainly composed of zinc oxide is provided downstream of the wet absorption method purification apparatus. The epitaxial growth of gallium nitride was repeated five times in the same manner as in Example 1 except that a filled dry purification cylinder was provided and dry nitrogen gas was introduced at 2 slm immediately before the dry purification cylinder.
[0031]
During this time, no clogging of ammonium chloride was observed. Further, the pressure difference between the reactor and the dry purification cylinder outlet was always 9 mmH ₂ O, and there was no sign of an increase in pressure loss in the entire purification apparatus.
Further, ammonia was not detected in the exhaust gas from the outlet of the dry purification cylinder. Furthermore, hydrogen chloride was not detected.
[0032]
In this case, the product of the value obtained by dividing the exhaust gas flow rate (cm ³ / sec) by the cross-sectional area (cm ² ) of the pipe and the length (cm) of the pipe is 298, which is in the range of 100 to 25000.
When the electrical characteristics of the GaN epitaxial layer grown in this experiment were evaluated, the same excellent characteristics as those obtained in Example 1 were shown.
[0033]
(Example 3)
The epitaxial growth of gallium nitride was repeated five times in the same manner as in Example 2 except that the pipe connecting the reactor and the wet absorption method purification apparatus in Example 2 was changed to an inner diameter of 3.1 cm and a length of 150 cm. .
[0034]
During this time, no ammonium chloride clogging was observed. Further, the pressure difference between the reactor and the dry purification cylinder outlet was always 9 mmH ₂ O, and there was no sign of an increase in pressure loss in the entire purification apparatus.
Further, neither ammonia nor hydrogen chloride was detected in the exhaust gas from the outlet of the dry purification cylinder.
The product of the value obtained by dividing the exhaust gas flow rate (cm ³ / sec) by the cross-sectional area (cm ² ) of the pipe in this case and the length (cm) of the pipe is 1657, which is in the range of 100 to 25000.
When the electrical characteristics of the GaN epitaxial layer grown in this experiment were measured, the same excellent characteristics as those obtained in Example 1 were shown.
[0035]
Example 4
The epitaxial growth of gallium nitride was repeated five times in the same manner as in Example 2, except that the pipe connecting the reactor and the wet absorption method purification apparatus in Example 2 was changed to an inner diameter of 1.14 cm and a length of 150 cm. .
[0036]
During this time, no ammonium chloride clogging was observed. Further, the pressure difference between the reactor and the dry purification cylinder outlet was always 10 mmH ₂ O, and there was no sign of an increase in pressure loss in the entire purification apparatus.
Further, neither ammonia nor hydrogen chloride was detected in the exhaust gas from the outlet of the dry purification cylinder.
In this case, the product of the value obtained by dividing the exhaust gas flow rate (cm ³ / sec) by the cross-sectional area (cm ² ) of the pipe and the length (cm) of the pipe is 12240, which is in the range of 100 to 25000.
Note that the electrical characteristics of the GaN epitaxial layer grown in this experiment were measured. As a result, the same excellent characteristics as those obtained in Example 1 were exhibited.
[0037]
(Comparative Example 1)
The epitaxial growth of gallium nitride was repeated five times under the same conditions as in Example 2 except that the pipe connecting the reactor and the wet absorption purification device in Example 2 was changed to an inner diameter of 14.96 cm and a length of 100 cm.
[0038]
During this time, the pressure difference between the reactor and the dry purification cylinder outlet was constant at 9 mmH ₂ O.
In this case, the product of the value obtained by dividing the exhaust gas flow rate (cm ³ / sec) by the cross-sectional area (cm ² ) of the pipe and the length (cm) of the pipe is 47, which falls outside the scope of the present invention.
The characteristics of the GaN epitaxial layer grown in this experiment were evaluated. As a result, the electrical characteristics were a carrier concentration of 5E19 / cm ² and a carrier mobility of 75 cm ² / Vs. Further, when photoluminescence was measured, band edge emission was observed at 357 nm at 4.2 K, and emission in a long wavelength region was mixed.
[0039]
(Comparative Example 2)
Gallium nitride was grown in the same manner as in Example 2 except that the piping in Example 2 was changed to an inner diameter of 0.6 cm and a length of 100 cm.
In this case, the product of the value obtained by dividing the exhaust gas flow rate (cm ³ / sec) by the cross-sectional area (cm ² ) of the pipe and the length (cm) of the pipe is 29488, which falls outside the scope of the present invention.
The pressure difference between the reaction furnace and the dry purification tube outlet was initially 19 mmH ₂ O, but the pressure difference gradually increased during the vapor phase growth and reached 256 mmH ₂ O. For this reason, when the piping was removed and inspected, it was found that a large amount of ammonium chloride was adhered in the piping.
[0040]
【The invention's effect】
The exhaust gas purifying method and purifying apparatus according to the present invention enable epitaxial growth of gallium nitride without causing deterioration in semiconductor characteristics due to back diffusion of moisture. Further, according to the exhaust gas purification method and the purification device of the present invention, the exhaust gas flow path does not have a tight structure in which the gas flow is likely to be hindered unlike the purification apparatus using the dry adsorption method. Gallium nitride epitaxial growth can be repeatedly performed without causing clogging of ammonium chloride.
[Brief description of the drawings]
FIG. 1 is a schematic process diagram showing an example of a semiconductor manufacturing apparatus and an exhaust gas purifying apparatus of the present invention.
DESCRIPTION OF SYMBOLS 1 Reactor 2 Heater 3 Mixed gas supply piping 3 'of ammonia and hydrogen Mixed gas supply piping 4' of hydrogen chloride and hydrogen 4 Exhaust gas outlet 5 Metal gallium boat 6 Substrate 7 Susceptor 8 Piping 9 Wet absorption purification device 10 Absorption cylinder 11 Spray nozzle 12 Absorption liquid 13 Pump 14 Multilayer filter 15 Absorption liquid circulation pipe 16 Absorption cylinder outlet pipe 17 Mist separator 18 Mist separator return pipe 19 Nitrogen supply pipe 20 Dry purification cylinder inlet pipe 21 Dry purification cylinder 22 Dry purification agent 23 Exhaust gas purge line

Claims (2)

Treats exhaust gas from gallium nitride film semiconductor manufacturing equipment, which uses gallium chloride (GaCl) gas generated by flowing hydrogen chloride gas through metal gallium as a gallium source and is vapor-phase grown by reaction with ammonia. In the wet absorption method exhaust gas purification method, the relationship between the pipe connecting the production apparatus and the wet absorption method exhaust gas purification device and the exhaust gas flow rate in the pipe is expressed by the exhaust gas flow rate (cm ³ ) in terms of the cross-sectional area of the pipe (cm ² ). A method for purifying exhaust gas, wherein a product of a value obtained by dividing (/ second) and a length (cm) of the pipe is in a range of 100 to 25000. 2. The exhaust gas purification method according to claim 1, wherein the absorbent used in the wet absorption method exhaust gas purification apparatus is hydrochloric acid or an aqueous solution of an acid having a lower acidity than hydrochloric acid .

Images