JP2006326553A - Apparatus for treating exhaust gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for treating an exhaust gas which avoids recombination of PFC (perfluoro compound) and brings about the high removing rate of PFC while preventing troubles such as clogging of pipes at the lower stage of an excitation section and a machine breakdown. <P>SOLUTION: The apparatus for treating an exhaust gas 10 which removes a hazardous gas constituent contained in the exhaust gas exhausted from manufacture equipment semiconductor 1 comprises a removing-by-reaction section A41 removing a part of the hazardous gas constituent, the excitation section 42 exciting a residual part of the hazardous gas constituent, a removing-by-reaction section B43 removing the hazardous gas constituent excited by the excitation section 42, and evacuation pumps 3, 44 for evacuating the semiconductor manufacture equipment 1 and the excitation section 42 respectively. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exhaust gas treatment apparatus that removes harmful gas components contained in exhaust gas discharged from a semiconductor manufacturing apparatus.

In recent years, in order to suppress global warming, emission regulations for PFCs (perfluorocompounds) with a high global warming potential have been strengthened, and absolute quantity reduction, that is, total quantity regulation has become essential rather than relative concentration reduction by dilution. Yes. In addition to inert gases such as Ar, Kr, Xe, He, and N ₂ , CF ₄ , C ₂ F ₄ , C ₂ F ₆ , C ₃ F ₈ , and C ₄ are included in the exhaust gas discharged from the semiconductor manufacturing apparatus. F ₆ , C ₄ F ₈ , C ₅ F ₈ , COF ₂ , CO, CO ₂ , HF, SiF ₄ and many other types of fluoride gas are included, and these are decomposed and removed more efficiently. It is hoped to do.

As a device widely used for the purpose of removing the PFC component from the exhaust gas, there is a plasma abatement device. In this method, high-frequency and high-voltage electricity is used to turn a gas into a plasma, and the PFC gas is decomposed and removed with the energy. When even the fluorine component or carbon component after decomposition is present in an unstable state, or form deposits plasma chamber wall, PFC by recombination, primarily due to or form CF _4, usually O ₂ Ya Excess oxidizing agent such as H ₂ O is additionally introduced for removal. Therefore, in order to increase the PFC processing flow rate while maintaining a predetermined PFC removal rate, it is necessary to increase the oxidant flow rate or increase the plasma energy in accordance with the increase in the PFC processing flow rate.

  For example, in an etching apparatus, in each gas exhausted by each process such as wafer conveyance, pressure stabilization after gas introduction into the chamber, etching process (RF-ON), and the type of wafer to be etched. Since the PFC flow rate fluctuates greatly, a plasma abatement apparatus that can process the maximum flow rate PFC is usually required. In view of this, a method has been proposed for reducing the burden on the plasma abatement apparatus by installing an adsorbent on the upper stage of the plasma unit to mitigate an instantaneous increase in the PFC flow rate (see, for example, Patent Document 1).

However, since the exhaust gas of a semiconductor manufacturing apparatus may contain Si components such as SiF ₄ , when an oxidant is added and plasma discharge is performed, SiO ₂ powder is generated, and piping is clogged at the lower stage of the plasma apparatus. Or cause equipment failure. In the invention described in Patent Document 1, any one of zeolite, activated carbon, and porous ceramics is used as an adsorbent, but it does not remove a specific Si component and is used as it is for treatment of exhaust gas containing SiF _4. I can't do it.

  In addition, the amount of plasma energy required is affected not only by the PFC flow rate introduced into the plasma generator, but also by the total flow rate of the gas including the oxidant. This is because energy is also consumed for decomposition of gas components other than PFC.

  Generally, as a means for increasing the plasma energy, a high-frequency power source, that is, a high-power output of the plasma generator, is used. Becomes so large that it cannot be installed in a limited space such as a semiconductor manufacturing factory. Therefore, a means for increasing the total plasma energy by installing a plurality of microwave plasma generators in a single chamber has been proposed (see, for example, Patent Document 2). According to the present invention, it is possible to process a larger flow rate PFC by using an inexpensive and small plasma generator.

  However, in PFC decomposition using plasma, the PFC recombination rate (removal rate) in a single chamber cannot be completely prevented even if the oxidizing agent is optimized. Often 99% is the upper limit. From the viewpoint of total amount regulation, it is strongly desired to further improve the decomposition rate and reduce the PFC flow rate in the exhaust gas from the abatement apparatus.

Further, Ar, Kr, and Xe are rare and expensive gases, so-called rare gases, and are contained in the exhaust gas in a large amount. For example, the rare gas in the exhaust gas from the semiconductor manufacturing apparatus is recovered, Reuse is performed (see, for example, Patent Document 3). However, in order to recover these rare gases, it is necessary to previously remove harmful gas components contained in the exhaust gas, for example, fluoride gases such as CF ₄ and SiF ₄ with high efficiency.
JP 2003-245520 A JP 2001-129359 A JP 11-157814 A

  As described above, in order to release the exhaust gas discharged from the semiconductor manufacturing apparatus to the atmosphere, or to recover and reuse the rare gas component in the exhaust gas, harmful gas components such as PFC contained in the exhaust gas Must be removed more efficiently.

  However, in the case of the conventional general plasma abatement apparatus, it is possible to increase the processing flow rate by increasing the plasma source output, but there is a problem that the removal efficiency is limited to about 99%.

Further, when the Si-based gas is processed by the plasma abatement apparatus or the combustion abatement apparatus, there is a problem that powder such as SiO ₂ is generated, causing piping blockage and equipment damage at the lower stage of the abatement apparatus.

  The present invention has been made in view of the above problems of the background art, and can prevent recombination of PFCs to achieve a high PFC removal rate, and can also prevent troubles such as piping clogging or equipment failure at the lower stage of the excitation unit. An object of the present invention is to provide an exhaust gas treatment apparatus that prevents the above.

To solve this problem,
The invention according to claim 1 is an apparatus for removing harmful gas components contained in exhaust gas discharged from a semiconductor manufacturing apparatus, wherein the reaction removing unit A removes a part of the harmful gas components, and the harmful gas components. An exciter that activates the remainder of the gas, a reaction removal unit B that removes harmful gas components activated in the exciter, and an exhaust pump that depressurizes the semiconductor manufacturing apparatus and the exciter. An exhaust gas treatment apparatus characterized by

  The invention according to claim 2 is the exhaust gas treatment apparatus according to claim 1, further comprising at least one excitation unit and one reaction removal unit B at a lower stage of the excitation unit and the reaction removal unit B. .

  The invention according to claim 3 is the exhaust gas treatment apparatus according to claim 1 or 2, further comprising an oxidant supply unit at an upper stage of the excitation unit.

  The invention according to claim 4 is the method according to any one of claims 1 to 3, wherein the reaction removal unit A and the reaction removal unit B include any one of calcium oxide, calcium hydroxide, and a mixture thereof. An exhaust gas treatment device.

  The invention according to claim 5 is the exhaust gas treatment apparatus according to any one of claims 1 to 4, wherein the excitation unit is a plasma generation device or an ultraviolet light irradiation device.

  The invention according to claim 6 is provided with a heating means for heating a pipe between the semiconductor manufacturing apparatus and the reaction removal section A. The exhaust gas according to any one of claims 1 to 5, It is a processing device.

According to the exhaust gas treatment apparatus of the present invention, by providing the reaction removal unit A in the upper stage of the excitation unit, the amount of PFC treatment in the excitation unit is reduced, and piping clogging caused by SiO ₂ powder in the lower stage of the excitation unit And troubles such as equipment failures can be prevented.

  In addition, by providing the reaction removal unit A in the upper stage of the excitation unit, the reaction removal unit A can serve as a buffer tank, and can reduce the instantaneous maximum flow rate of harmful gas components and reduce the load on the excitation unit. The amount of energy required to activate the remainder of the harmful gas component in the excitation part can be reduced.

  In addition, according to the present invention, the harmful gas component is removed by the excitation unit and the reaction removal unit B, so that the remainder of the harmful gas component activated in the excitation unit is not recombined into the reaction removal unit B. Since it is sent and removed, PFC recombination can be prevented and a high PFC removal rate can be achieved.

  Hereinafter, an example of an exhaust gas treatment apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a schematic configuration diagram illustrating an exhaust gas treatment apparatus 10 according to the present embodiment. The exhaust gas treatment apparatus 10 is generally configured by an exhaust pump 3 provided at the lower stage of the semiconductor manufacturing apparatus 1 and an exhaust gas treatment unit 4.

  Examples of the semiconductor manufacturing apparatus 1 include an apparatus used for manufacturing a semiconductor device such as a reactive plasma etching apparatus. An exhaust pump 3 is connected to the semiconductor manufacturing apparatus 1 via a pipe 2 so that the generated exhaust gas can be sucked by the exhaust pump 3 and introduced into the lower exhaust gas treatment unit 4.

  The exhaust gas treatment unit 4 includes a reaction removal unit A41, an oxidant supply unit 45, an excitation unit 42, a reaction removal unit B43, and an exhaust pump 44 that sucks exhaust gas in this order. The reaction removal unit A41 removes a part of the harmful gas components contained in the exhaust gas fed by the exhaust pump 3, and the excitation unit 42 and the reaction removal unit B43 are harmful that has passed through the reaction removal unit A41. The remainder of the gas component is activated and removed. The oxidant supply unit 45 additionally supplies an oxidant in order to promote activation of the remaining harmful gas components in the excitation unit 42. As such an oxidizing agent, for example, oxygen gas or ozone gas can be used.

The reaction removal unit A41 removes some of harmful gas components contained in the exhaust gas, in particular, silicon-containing components including SiF ₄ , hydrogen fluoride, and mixtures thereof, and is made of a material such as quartz or stainless steel. A cylindrical agent-filling cylinder is provided. The reaction removal unit A41 is filled with a reaction removal agent containing any of granular calcium oxide, calcium hydroxide, and a mixture thereof.

  Moreover, it is preferable to provide a filter for preventing leakage of the reaction removal agent at the bottom of the agent-filled cylinder of the reaction removal portion A41. The reaction removing agent is preferably filled in the agent-filled cylinder with a porosity of 30 to 70% by volume. By filling the reaction remover with a porosity of 30 to 70% by volume, the flow of exhaust gas in the reaction removal unit A41 can be prevented.

  Examples of such a reaction removing agent include those formed into granules or granules by rolling, tableting, extrusion molding or the like. Among them, those having a particle size of 0.5 to 10 mm are preferable. By setting the particle size of the reaction removing agent to 0.5 to 10 mm, it becomes easy to fill the reaction removing portion A41 with a porosity of 30% by volume or more without exciting the exhaust gas flow. It is easy to control the pressure of the part 42 to a predetermined value, and it becomes easy to fill the reaction removal part A41 with a porosity of 70% by volume or less. It is possible to improve the utilization efficiency of the reaction remover by increasing the contact probability of the reaction remover.

  Moreover, when using calcium oxide as a reaction removal agent, it is preferable to use what formed the calcium carbonate by baking the shape | molded calcium carbonate and having evaporated the carbon dioxide. Part of the surface of such granular calcium oxide is changed to calcium hydroxide due to moisture in the air, and this calcium hydroxide is involved in the actual removal reaction.

  Moreover, it is also possible to use what formed the fine void | hole in the inside by baking the calcium hydroxide shape | molded to granular form and evaporating a water | moisture content. By using this method, it is possible to arbitrarily adjust the mixing ratio of calcium oxide and calcium hydroxide.

  Moreover, the excitation part 42 is arrange | positioned in the lower stage of reaction removal part A41, and activates the remainder of the harmful gas component which passed reaction removal part A41. The excitation unit 42 is roughly configured from a cylindrical processing tube made of alumina or the like, a high-frequency coil wound around the processing tube, and an AC power source that supplies a high-frequency current of 1 to 100 MHz to the high-frequency coil. Yes. A reaction removal unit B43 is connected to the lower stage of the processing tube.

  The excitation unit 42 can supply a high-frequency current from an AC power source to the high-frequency coil so that the gas inside the processing tube can be in a plasma state, and the output can be adjusted according to the type of gas introduced. Is possible. Examples of the plasma include inductively coupled plasma, but are not limited thereto.

  In the present embodiment, a high-frequency plasma generator is used for the excitation unit 42. However, by changing the high-frequency coil on the outer periphery of the processing tube to a waveguide and supplying a high-frequency current of 2.45 GHz, Can be microwave plasma.

  Alternatively, an ultraviolet light irradiation device is used as the excitation unit 42, and a high-energy light such as vacuum ultraviolet light or ultraviolet light is transmitted through a gas flow path provided with a light transmission window instead of a processing tube. The gas molecules may be excited by irradiation. Examples of such an ultraviolet light irradiation apparatus include those using an Xe lamp or a deuterium lamp as a light generation source, but are not limited thereto.

  In addition, when the excitation energy is insufficient, exhaust gas after irradiation with ultraviolet light can be introduced into the plasma apparatus, and high energy can be easily given by combining plasma and light irradiation. . In this case, since the oxygen is in an active state such as ozone by irradiation with ultraviolet light, the oxidant utilization efficiency in the processing tube of the plasma apparatus is improved, and the oxidant flow rate introduced from the oxidant supply unit 45 is suppressed. An effect is obtained.

  The reaction removal unit B43 is for removing the fluoride gas that is the remaining harmful gas component activated by the excitation unit 42, and includes a cylindrical agent-filled cylinder. The reaction removal unit B43 is filled with the same reaction removal agent as the reaction removal unit A41.

  This agent-filled cylinder is detachably attached to the processing tube of the exciter 42 by a flange or the like so that the reaction removal agent filled therein can be replaced as necessary. Moreover, it is preferable to use a pipe having a large diameter and a short length, and more preferably a pipe having a diameter of 2 cm or more and a length of 50 cm or less for the connection between the reaction removal unit B43 and the excitation unit 42.

  In addition, it is preferable to select a material having high durability against fluoride gas for the reaction removal unit B43 and the connection pipe, or it is preferable to use a material that has been surface-treated to improve durability against fluoride gas. As an example, stainless steel pipes subjected to fluorine passivation treatment and the like can be mentioned.

  As the exhaust pumps 3 and 44, a dry pump having high corrosion resistance can be used. Further, in general dry pumps, there are many that use nitrogen gas at a flow rate of 10 to 40 L / min as the purge gas and shaft seal gas for diluting the suction gas, but the flow rates of this purge gas and shaft seal gas are 3 L / min. In the following, it is preferable to use a pump that can be preferably 1 L / min or less. In particular, the exhaust pump 44 sucks the gas after the fluoride is removed, so that a pump that does not require a purge gas is most desirable.

  By using these pumps, it is possible to facilitate the purification of the rare gas when the exhaust gas after removal of harmful gas components is recovered. Note that the use of a pump with a small flow rate of purge gas and shaft seal gas as the exhaust pump 3 has the effect of facilitating pressure adjustment at the excitation unit 42 and the effect of suppressing energy required for excitation. .

  Further, the exhaust pump 44 is preferably provided with means for adjusting the pressure of the excitation unit 42. Examples of the means for adjusting the pressure include a means for controlling the motor rotation speed of the exhaust pump 44 and a means for providing a conductance adjustment valve at the intake port of the exhaust pump 44. The exhaust pump 44 sucks and exhausts gas while adjusting the pressure of the excitation unit 42 to 1 to 50 Torr (1 Torr = 133.32 Pa), preferably 2 to 20 Torr.

  In the present embodiment, an oxidant supply unit 45 is provided in the upper stage of the excitation unit 42. The oxidant supply unit 45 controls the oxidant concentration in the excitation unit 42 to be appropriate. Depending on the exhaust gas composition introduced into the excitation unit 42, a mass flow controller or a pressure-controlled flow regulator The oxidant can be additionally supplied while adjusting the flow rate with various flow rate adjusting devices such as the above. If the exhaust gas introduced into the excitation unit 42 contains sufficient oxidant to excite and activate the remainder of the harmful gas component in the excitation unit 42, the oxidant supply unit 45 may not be installed. .

  When the exhaust gas contains a rare gas to be recovered, such as Xe or Kr, a rare gas recovery and purification device is provided at the lower stage of the exhaust pump 44, and the gas discharged from the exhaust pump 44 is supplied to the rare gas. It is preferable to send it to a gas recovery and purification apparatus. As this rare gas recovery and purification apparatus, for example, a purification apparatus using a pressure fluctuation adsorption method (PSA method) or the like can be used.

  Next, a method for removing harmful gas components contained in the exhaust gas discharged from the semiconductor manufacturing apparatus 1 using the exhaust gas treatment apparatus 10 according to the present embodiment will be described below.

Examples of the process gas introduced into the semiconductor manufacturing apparatus 1 include gases such as Ar, Xe, CF ₄ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F ₆ , C ₄ F ₈ , and C ₅ F _8. It is done. In addition, during the step of stabilizing the pressure in the semiconductor manufacturing apparatus 1 (hereinafter referred to as “stabilization process”), the introduced gas is exhausted as it is as exhaust gas, and plasma, heating, etc. are performed in the semiconductor manufacturing apparatus 1. During the applied steps (hereinafter referred to as “processing steps”), Ar, Xe, CF ₄ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F ₆ , C ₄ F ₈ , and C ₅ F ₈ are included. In addition, gas containing C ₂ F ₄ , COF ₂ , CO, CO ₂ , HF, SiF _{4 and the} like is discharged as exhaust gas. Therefore, the exhaust gas containing these becomes the gas to be treated in the present invention. A part of the exhaust gas during the treatment process maintains an excited active state and exists as active species such as radicals.

The exhaust gas discharged from the semiconductor manufacturing apparatus 1 is sent to the exhaust pump 3 through the pipe line 2. Fluoride gases such as CF ₄ , C ₂ F ₄ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F ₆ , C ₄ F ₈ , C ₅ F ₈ , COF ₂ , HF, and SiF _{4 in} this exhaust gas , Silicon-containing components, hydrogen fluoride, and mixtures thereof are harmful gas components to be removed. In addition, depending on the semiconductor manufacturing apparatus 1, there may be cases where harmful gas components other than these, for example, GeH ₄ , B ₂ H ₆ , AsH _4, etc. are included, and in such cases, these gases should also be removed. It becomes a harmful gas component.

  The total amount of harmful gas components contained in such exhaust gas is about 0.1 to 25% in volume ratio, although it depends on the type and process of the semiconductor manufacturing apparatus 1.

The exhaust gas discharged from the exhaust pump 3 is introduced into the reaction removal unit A41 of the exhaust gas processing unit 4 in a reduced pressure state. Since the exhaust gas in the stabilization process passes through the reaction removal unit A41 without reacting because all component gases are in a stable state, the exhaust gas in the treatment process is, for example, from calcium oxide in the reaction removal unit A41. A reaction such as the following chemical reaction formulas (1) to (3) occurs with calcium hydroxide present on the surface of the reaction removal agent, and a part of harmful gas components such as COF ₂ , HF, and SiF ₄ are formed. Removed. At the same time, a reaction occurs between the fluoride gas that maintains the excited state and calcium oxide. As described above, since it is calcium hydroxide on the surface of the granular calcium oxide that is involved in the actual reaction, the chemical reaction formula is a reaction formula with calcium hydroxide.

SiF ₄ + 2Ca (OH) ₂ → 2CaF ₂ + SiO ₂ + 2H ₂ O (1)
COF ₂ + Ca (OH) ₂ → CaF ₂ + CO ₂ + H ₂ O (2)
2HF + Ca (OH) ₂ → CaF ₂ + 2H ₂ O (3)

  As shown in the chemical reaction formulas (1) to (3), the fluoride gas of the main component which is a part of the harmful gas component is fixed as calcium fluoride (fluorite) in the reaction removal unit A41. . Thereby, the density | concentration of the fluoride gas in the exhaust gas introduce | transduced into the excitation part 42 can be reduced.

  Further, since the reaction removal unit A41 serves as a buffer tank to alleviate fluctuations in the concentration of fluoride gas, the amount of energy required for activating the remainder of the harmful gas component in the excitation unit 42 can be reduced. it can.

At the same time, by providing the reaction removal unit A41 in the upper stage of the excitation unit 42, any of the silicon-containing component containing SiF ₄ in the exhaust gas, hydrogen fluoride, and a mixture thereof is completely removed by the reaction removal unit A41. Therefore, the PFC processing amount is reduced and the SiO ₂ powder is not generated in the excitation unit 42 and the lower stage thereof, and troubles such as piping blockage and equipment failure caused by the SiO ₂ powder can be prevented. it can.

  The remainder of the harmful gas component that has passed through the reaction removal unit A41 is introduced into the processing tube of the excitation unit. In the excitation unit 42, a high-frequency current is supplied from the AC power source to the high-frequency coil, plasma is generated in the processing tube, and each gas component in the exhaust gas introduced into the processing tube becomes active. At this time, each gas component changes to a state in which molecular bonds are completely broken by plasma, or to an excited state that maintains the bonds but has high energy.

At this time, carbon and fluoride generated by the PFC being decomposed by the plasma are in an unstable state, so that stable CF ₄ may be formed by recombination or may be deposited on the inner wall surface of the processing tube. . In order to prevent this, it is necessary to coexist a sufficient amount of oxygen atoms, for example, three times or more of carbon atoms. Also, if the oxidant concentration becomes too high, high energy power supply is required to form and maintain plasma. From these viewpoints, it is preferable to provide the oxidant supply unit 45 to appropriately control the oxidant flow rate.

  The exhaust gas activated by the excitation unit 42 is sent to the reaction removal unit B43, and reacts with the reaction removal agent filled therein to remove harmful gas components in the exhaust gas to a concentration equal to or lower than the target value. Thereafter, the air is exhausted by the exhaust pump 44.

For example, when the harmful gas component is CF ₄ , after being activated by the excitation unit 42, the fluorine component is removed and removed by the reaction removal unit B 43. The chemical reaction formula is as shown in the following formula (4). As described above, since it is calcium hydroxide on the surface of the granular calcium oxide that is involved in the actual reaction, the chemical reaction formula is a reaction formula with calcium hydroxide.

CF ₄ + 2Ca (OH) ₂ → 2CaF ₂ + CO ₂ + 2H ₂ O (4)
A similar reaction occurs in the case of fluoride gases such as C ₂ F ₄ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F ₆ , C ₄ F ₈ , and C ₅ F ₈ .

  The exhaust gas discharged from the exhaust pump 44 is discharged into the atmosphere through a duct or sent to a rare gas recovery and purification device to collect and reuse rare gases such as Ar and Xe. The purge gas flow rate of the exhaust pump 44 is preferably 3 L / min or less. By using an exhaust pump having a purge gas flow rate of 3 L / min or less, it is possible to facilitate the purification of the rare gas when the exhaust gas after removal of harmful gas components is recovered. Further, by setting the purge gas flow rate of the exhaust pump 44 provided to depressurize the excitation unit 42 to 3 L / min or less, the effect of facilitating the pressure adjustment in the excitation unit 42 and the energy necessary for excitation are suppressed. Effect is obtained.

  The reaction removal agent filled in the reaction removal unit A41 and the reaction removal unit B43 has a reduction reaction capability as the removal reaction proceeds. When the removal ability of the reaction remover has almost disappeared, it is necessary to replace it with a new reaction remover. For this reason, when two or more exhaust gas treatment units 4 are installed in parallel in the lower stage of the exhaust pump 3 and the removal reaction capacity of the reaction remover of the exhaust gas treatment unit 4 used is lowered, the remaining exhaust gas If it is used so as to switch to the processing unit 4, continuous operation is possible.

  Furthermore, it is also possible to arrange a heater on the outside of the agent filling cylinder of the reaction removal unit A41 and the reaction removal unit B43, and to heat the agent filling cylinder to a high temperature with this heater. The reaction removal unit A41 is preferably heated for the purpose of promoting the reaction between the reaction removal agent and the harmful gas component. Although the reaction is promoted as the temperature is higher, it is more preferable to heat to 100 to 300 ° C. from the viewpoint of power consumption for heating and heat resistance of peripheral devices.

  While the reaction removal unit B43 can maintain the excited state of the exhaust gas by heating, the load on the exhaust pump 44 increases due to the volume increase accompanying heating, so even when heating, about 50 to 100 ° C It is preferable that the

  In addition, since the chemical reaction formulas (1) to (4) are all exothermic reactions, the temperature of the reaction removal units A41 and B43 may exceed the set temperature due to fluctuations in the amount of gas introduced. In that case, it is preferable to keep the temperature of the agent-filled cylinder stable and constant by arranging a cooling water pipe or the like outside the reaction removal portions A41 and B43.

In the exhaust gas treatment apparatus and treatment method according to the present embodiment, the reaction removal unit A41 is provided in the upper stage of the excitation unit 42, so that any of the silicon-containing component, hydrogen fluoride, and a mixture thereof is removed by the reaction removal unit A41. In addition, since no SiO ₂ powder is generated, the amount of PFC processing in the excitation unit 42 is reduced, and troubles such as piping clogging and equipment failure caused by the SiO ₂ powder in the lower stage of the excitation unit 42 are eliminated. Can be prevented.

  Moreover, you may provide heating means, such as a heater which heats piping between the semiconductor manufacturing apparatus 1 and reaction removal part A41. In the state where moisture is adsorbed on the inner wall surface of the pipe, reactivity such as fluoride gas on the inner wall surface of the pipe is increased to produce deposits. It is because the production | generation and corrosion of this can be suppressed. The heating temperature is suitably about 100 to 150 ° C.

  Further, by providing the reaction removal unit A41 in the upper stage of the excitation unit 42, the reaction removal unit A41 plays the role of a buffer tank, and reduces the instantaneous maximum flow rate of harmful gas components, thereby reducing the load (required output) of the excitation unit 42. Since it can be made small, the amount of energy required to activate the remainder of the harmful gas component in the excitation unit 42 can be reduced.

  In addition, by removing the harmful gas component in the exhaust gas by the excitation unit 42 and the reaction removal unit B43, the remainder of the harmful gas component activated by the excitation unit 42 is not recombined to the reaction removal unit B43. Since it is sent and removed, PFC recombination can be prevented and a high PFC removal rate can be achieved.

[Second Embodiment]
FIG. 2 is a schematic configuration diagram illustrating the exhaust gas treatment apparatus 10 according to the present embodiment. This embodiment is the same as the first embodiment except that one or more excitation units 46 and reaction removal units B47 are further provided below the excitation unit 42 and the reaction removal unit B43. Description is omitted.

  In the present embodiment, an oxidant supply unit 49, an excitation unit 46, a reaction removal unit B47, and an exhaust pump 48 are provided in this order in the lower stage of the exhaust pump 44. The oxidant supply unit 49, excitation unit 46, reaction removal unit B47, and exhaust pump 48 are the same as the oxidant supply unit 45, excitation unit 42, reaction removal unit B43, and exhaust pump 44 shown in the first embodiment. Can be used.

  In the present embodiment, one or more excitation units 46 and reaction removal units B47 are provided below the excitation unit 42 and the reaction removal unit B43, so that the PFC concentration in the exhaust gas in the first-stage exhaust pump 44 is provided. Can be discharged after the PFC concentration in the exhaust gas is reduced below the target value by repeatedly performing the removal in the lower excitation unit 46 and the reaction removal unit B47 even if the value exceeds the target value. .

  In addition, since a commercially available inexpensive plasma generator or ultraviolet light irradiation device can be used for the excitation units 42 and 46, the exhaust gas may be configured to include one or more excitation units 46 and reaction removal units B47. Cost reduction and development speed improvement of the entire processing apparatus 10 can be achieved.

  Hereinafter, the present invention will be described in more detail with reference to experimental examples. The present invention is not limited to the following experimental examples.

[Experimental Examples 1-2] Regarding Pipe Blocking Caused by SiO ₂ Powder In the case where SiF ₄ gas is included in the time-dependent change in pressure of the microwave plasma generator 42 when plasma decomposition is performed by continuously flowing CF ₄ gas ( Comparison was made between Experimental Example 1) and the case where it was not included (Experimental Example 2). The exhaust gas treatment apparatus shown in FIG. 3 was used. Reference numeral 11 in FIG. 3 indicates a mass flow controller, 42 is a microwave plasma generator, 43 is a reaction remover, and 44 is an exhaust pump. Unlike the exhaust gas treatment apparatus of the present invention, this exhaust gas treatment apparatus does not have the reaction removal unit A41.

In Example 1, the composition of the _{gas, Ar: 96.19%, CF 4} : 0.18%, SiF 4: 0.36%, O 2: a 3.27%, total flow rate is 275.5Cc / min It was. In Experimental Example 2, the gas composition was Ar: 96.19%, CF ₄ : 0.54%, O ₂ : 3.27%, and the total flow rate was also 275.5 cc / min. Here, both F component density | concentration was made the same. FIG. 4 is a graph showing the relationship between the plasma processing elapsed time and the change in pressure of the microwave plasma generator.

In Experimental Example 1 containing SiF ₄ gas, it was found that the pressure of the microwave plasma generator increased with time. On the other hand, in Experimental Example 2 that did not contain SiF ₄ gas, the pressure did not change.

Further, after the experiment, the microwave plasma generator was disassembled and the inside was observed. In Experimental Example 1 containing SiF ₄ gas, SiO ₂ powder was deposited on the inner wall surface of the lower pipe of the microwave plasma generator. It was confirmed that From the above results, if the reaction removal unit A41 is not provided at the upper stage of the excitation unit 42, SiF _{4 in} the exhaust gas is directly introduced into the excitation unit 42 to generate SiO ₂ powder, and the lower piping of the excitation unit 42 It was confirmed to block.

[Experimental Examples 3 to 4]
The exhaust gas from the semiconductor manufacturing apparatus 1 was processed using the exhaust gas processing apparatus 10 shown in FIG. As the agent filling cylinder of the reaction removal unit A41, the reaction removal unit B43, and the reaction removal unit B47, a stainless steel bottomed cylindrical body having an inner diameter of 150 mm and a length of 600 mm is used. It was filled with 3000 g of calcium oxide so that the porosity was 50% by volume.

  In Experimental Example 3, a commercially available microwave plasma generator was used for the excitation units 42 and 46. This microwave plasma generator uses an alumina cylindrical tube with an inner diameter of 42 mm as a processing tube, and supplies a microwave with a frequency of 2.45 GHz from an AC power source with a maximum output of 1.5 kW, and the inside of the processing tube is microscopic. Wave plasma is generated.

Next, the exhaust pump 44 and the exhaust pump 48 were operated, and the exhaust gas from the semiconductor manufacturing apparatus 1 was introduced into the exhaust gas treatment unit 4 via the pipe line 2 and the exhaust pump 3. When the semiconductor manufacturing apparatus 1 is in the pressure stabilization process, the composition of the gas introduced into the exhaust gas treatment unit 4 is Ar: 94%, CF ₄ : 2%, C ₄ F ₈ : 1%, O ₂ : 3 %Met.

Here, while supplying oxygen from the oxidant supply unit 45 and the oxidant supply unit 49, the pressures of the excitation unit 42 and the excitation unit 46 are adjusted to 5 Torr, respectively, and plasma is generated from the exhaust pump 48. The CF ₄ concentration in the exhaust gas discharged was analyzed by FT-IR. At this time, the CF ₄ concentration was 200 ppm, and the removal rate was 99%.

In Experimental Example 4, the same microwave plasma generator as in Experimental Example 3 was used for the excitation unit 42, and a commercially available high-frequency plasma generator was used as the excitation unit 46. This high-frequency plasma generator uses a cylindrical tube made of alumina with an inner diameter of 80 mm as a processing tube, and applies a high-frequency current with a frequency of 2 MHz from an AC power source with a maximum output of 3.0 kW to a high-frequency coil wound around the outer periphery. Inductively coupled plasma is generated inside the processing tube. Otherwise, the same procedure as in Experimental Example 3 was performed. The CF ₄ concentration at this time was 2 ppm, and the removal rate was 99.99%.

FIG. 5 shows the relationship between the total amount of plasma power and the residual CF ₄ concentration. From the result of FIG. 5, it was found that a high removal rate can be obtained with a commercially available inexpensive plasma source by providing one or more excitation units and reaction removal units B in the lower stage of the reaction removal unit A.

[Experimental Examples 5-6]
The exhaust gas from the semiconductor manufacturing apparatus 1 was processed using the exhaust gas processing apparatus 10 shown in FIG. As the agent filling cylinders of the reaction removal unit A41, the reaction removal unit B43, and the reaction removal unit B47, the same ones as in Experimental Example 3 were used. In addition, a commercially available microwave plasma generator similar to Experimental Example 3 was used as the excitation unit 42. As the excitation unit 46, a commercially available high-frequency plasma generator similar to that in Experimental Example 4 was used.

  The exhaust pump 44 and the exhaust pump 48 were operated, and the exhaust gas from the semiconductor manufacturing apparatus 1 was introduced into the exhaust gas processing unit 4 via the pipe line 2 and the exhaust pump 3. The composition of the gas introduced into the exhaust gas treatment unit 4 when the semiconductor manufacturing apparatus 1 was in the pressure stabilization process was the same as in Experimental Examples 3-4.

  In Experimental Example 5, the fluoride gas in the exhaust gas from the exhaust pump 48 was analyzed by FT-IR, and in Experimental Example 6, the fluoride gas in the exhaust gas from the exhaust pump 3 was analyzed by FT-IR. A chart of the results of this FT-IR is shown in FIG.

According to FIG. 6, COF ₂ , C ₂ F ₄ , CF ₄ , C ₂ F ₆ , CHF ₃ , and SiF ₄ peaks were observed in the exhaust gas from the exhaust pump 3 of Experimental Example 6. On the other hand, in the exhaust gas of the exhaust pump 48 of Experimental Example 5, these peaks were below the detection limit and were not observed. The same result was obtained even when the operation was continued for 4 hours. From the above results, it was found that the use of the exhaust gas treatment apparatus 10 can remove PFC in the exhaust gas without any problem.

1 is a schematic configuration diagram illustrating an exhaust gas treatment apparatus according to a first embodiment. It is the schematic block diagram which showed the exhaust gas processing apparatus which concerns on 2nd Embodiment. It is the schematic block diagram which showed the exhaust gas processing apparatus used for Experimental example 1-2. It is the graph which showed the relationship between the plasma processing elapsed time in Experimental Examples 1-2, and the change of the pressure of a microwave plasma generator. Is a graph showing the relationship between the CF ₄ concentration remaining the total amount of plasma power in Experimental Example 3-4. It is the chart which showed the result of FT-IR in Experimental examples 5-6.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor manufacturing apparatus 3,44,48 Exhaust pump 10 Exhaust gas processing apparatus 41 Reaction removal part A
42,46 Excitation part 43,47 Reaction removal part B
45, 49 Oxidant supply section

Claims (6)

An apparatus for removing harmful gas components contained in exhaust gas discharged from a semiconductor manufacturing apparatus,
A reaction removal unit A for removing a part of the harmful gas component;
An excitation unit that activates the remainder of the harmful gas component;
A reaction removal unit B for removing harmful gas components activated in the excitation unit;
An exhaust gas treatment apparatus comprising an exhaust pump for depressurizing the semiconductor manufacturing apparatus and the excitation unit.   The exhaust gas treatment apparatus according to claim 1, further comprising at least one excitation unit and one reaction removal unit B at a lower stage of the excitation unit and the reaction removal unit B.   The exhaust gas treatment apparatus according to claim 1, further comprising an oxidant supply unit at an upper stage of the excitation unit.   The exhaust gas treatment apparatus according to any one of claims 1 to 3, wherein the reaction removal unit A and the reaction removal unit B include any one of calcium oxide, calcium hydroxide, and a mixture thereof.   The exhaust gas treatment apparatus according to any one of claims 1 to 4, wherein the excitation unit is a plasma generator or an ultraviolet light irradiation device. The exhaust gas treatment apparatus according to any one of claims 1 to 5, further comprising a heating unit that heats a pipe between the semiconductor manufacturing apparatus and the reaction removal unit A.

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