Patent Description:
In a semiconductor manufacturing treatment process, for example, dry etching treatment or chemical vapor deposition (CVD) in which a semiconductor, an insulator, a metal film, or the like is deposited on a semiconductor wafer in order to form a film through chemical vapor reaction, are performed. In a process chamber, various gases such as silane (SiH<NUM>) gas are used. The used gas exhausted from the process chamber is sucked by a dry pump or the like, further introduced into a detoxification device via a gas exhaust pipe, and subjected to detoxification treatment in the detoxification device.

In such a semiconductor manufacturing treatment process, when the foregoing used gas is subjected to cooling or the like, the used gas is solidified into a film or powder and adhere to the insides of an exhaust pipe other than that of the process chamber, the dry pump, and the detoxification device, and result in a deposit. The deposit clogs the pipe, resulting in the need of frequent maintenance.

For the maintenance, in a conventional semiconductor manufacturing treatment process, upon each end of process treatment, a cleaning gas of chlorine trifluoride (ClF<NUM>), nitrogen trifluoride (NF<NUM>), or hydrogen chloride (HCl), or the like is periodically introduced into the process chamber in accordance with the type of an adhering product. The introduced cleaning gas is led to each of the spots where semiconductor wafers are deposited to resolve and exhaust an adhering material and thus clean a reaction chamber, an exhaust pipe, a dry pump, and a detoxification device in a semiconductor treatment apparatus (see, e.g., <CIT>).

In general, as such a used gas and a cleaning gas are heated to a higher temperature of not less than <NUM>, the function of resolving and exhausting the adhering material can more efficiently be performed.

Accordingly, the used gas and the cleaning gas (hereinafter such gases are generally referred to as "used gas") flowing from the process chamber through the dry pump toward the detoxification device several meters away from the dry pump are preferably held at a high temperature of not less than <NUM> when introduced into the detoxification device.

In view of this, a method has also been proposed in which, between a dry pump and a detoxification device, a diluent gas heated to about <NUM> is added to the used gas exhausted from the dry pump to be mixed with the used gas. The used gas is thus heated to <NUM> to <NUM> and introduced into the detoxification device (see, e.g., <CIT>).

The invention described in <CIT> uses an electrically heated wire as a heat source for heating the diluent gas.

As described above, conventionally, an electrically heated wire has been used as a heat source for heating a diluent gas. As a result, a problem arises in that a large amount of electric power is consumed to heat the electrically heated wire.

The present invention has been achieved in view of such a conventional problem. An object of the present invention is to provide a dry pump and an exhaust gas treatment method which can improve an effect of inhibiting a reaction product from adhering to the inside of a gas outlet port of the dry pump, a gas exhaust pipe, or the like and can also improve an energy saving effect. Documents <CIT> and <CIT> both disclose providing heated purge gas to an exhaust pipe by absorbing heat from the exhaust pipe prior to its addition. Document <CIT> discloses passing a diluent through a annulus in a stator to prevent corrosion of an O-ring. No control of the temperature of the diluent is disclosed.

The present invention has been proposed to attain the foregoing object. The invention in accordance with a first aspect is a dry pump according to Claim <NUM>.

With the configuration, it is possible to introduce the diluent gas heated using the heat generated from the dry pump into either the gas outlet port of the dry pump or the gas exhaust pipe connected to the gas outlet port, mix the diluent gas with the gas from the process chamber, and heat and dilute the gas from the process chamber. As a result, when the gas from the process chamber and the diluent gas are introduced into a detoxification device and subjected to detoxification treatment, each of the gases is heated. This can prevent a reaction product such as a film or powder included in the gases from being solidified in the detoxification device or the gas exhaust pipe to adhere to the inside thereof, and also from being deposited thereon to clog the pipe. In addition, since such gases are heated using the heat generated from the dry pump, instead of using an electrically heated wire as in a conventional device, it is possible to eliminate power consumption and contribute to energy saving.

The invention in accordance with a second aspect is the dry pump in accordance with the first aspect, wherein, by introducing the diluent gas, a gas in either the gas outlet port or the gas exhaust pipe is heated to a temperature of not less than a predetermined value.

In the configuration, the gas in either the gas outlet port or the gas exhaust pipe is heated to a temperature which prevents a reaction product such as a film or powder from being solidified in, e.g., a detoxification device and adhering to the inside thereof. Thus, it is possible to prevent a reaction product such as a film or powder included in each of the gas from the process chamber and the diluent gas from being solidified and adhering to the inside of the detoxification device and the gas exhaust pipe.

The invention in accordance with an third aspect the sealing (diluent) gas is introduced into a pump chamber of the dry pump.

The configuration allows the pump chamber where a pressure increases to be easily sealed using the sealing (diluent) gas.

The invention in accordance with a forth aspect is the dry pump in accordance with the third aspect, wherein an outlet port through which the sealing gas is exhausted to the outside of the dry pump is provided in an upstream of an inlet port through which the sealing (diluent) gas is introduced into the pump chamber of the dry pump.

In the configuration, the outlet port through which the sealing gas is exhausted to the outside of the dry pump is provided upstream of the inlet port through which the sealing (diluent) gas is introduced into the dry pump. This allows the structure to be simplified.

The invention in accordance with a fifth aspect is the dry pump in accordance with the forth aspect, wherein the sealing (diluent) gas is introduced into a final chamber of the pump chambers of the dry pump.

The configuration allows the final pump chamber where a pressure is highest to be easily sealed using the sealing (diluent) gas.

The invention in accordance with an sixth aspect is the dry pump in accordance with the first, second, third, fourth, fifth, aspect, wherein the diluent gas is a nitrogen (N<NUM>) gas.

The configuration allows the gas from the process chamber and the diluent gas to be easily heated to a temperature of not less than the predetermined value using the nitrogen (N<NUM>) gas.

The invention in accordance with a seventh aspect is the dry pump in accordance with the first, second, third, fourth, fifth, or sixth aspect, wherein the introduction of the diluent gas is controlled by a control device.

The configuration allows the diluent gas to be automatically introduced in an optimum state under the control of the control device.

The invention in accordance with a eighth aspect is an exhaust gas treatment method according to Claim <NUM>.

The method allows the diluent gas heated using the heat generated from the dry pump to be mixed with the gas from the process chamber to allow the gas from the process chamber to be heated and diluted. As a result, when the gas from the process chamber and the diluent gas are introduced into a detoxification device and subjected to detoxification treatment, each of the gases is heated. This can prevent a reaction product such as a film or powder included in the gases from being solidified in the detoxification device or the gas exhaust pipe to adhere to the inside thereof, and also from being deposited thereon to clog the pipe. In addition, since the gases are heated using the heat generated from the dry pump, instead of using an electrically heated wire as in a conventional device, it is possible to eliminate power consumption and contribute to energy saving.

By introducing the diluent gas, the gas from the process chamber is heated to a temperature of not less than a predetermined value.

In accordance with the method, when the gas from the process chamber and the diluent gas are introduced into a detoxification device and subjected to detoxification treatment, each of the gases is heated. This can prevent a reaction product such as a film or powder included in the gases from being solidified in the detoxification device or the gas exhaust pipe to adhere to the inside thereof, and also from being deposited thereon to clog the pipe.

The present invention can provide a dry pump and an exhaust gas treatment method which can improve the effect of inhibiting a reaction product from adhering to the inside of a gas outlet port (including also a portion extending from an outlet of a pump chamber to the outlet port) of the dry pump or a gas exhaust pipe and can also improve an energy saving effect.

An object of the present invention is to provide a dry pump which can improve an effect of inhibiting a reaction product from adhering to the inside of a gas outlet port of the dry pump or a gas exhaust pipe and can also improve an energy saving effect. To attain the object, the present invention is achieved by introducing, in the dry pump which sucks in a gas exhausted from a process chamber, a diluent gas heated using a heat generated from the dry pump into either the gas outlet port of the dry pump or the gas exhaust pipe connected to the gas outlet port.

Another object of the present invention is to provide an exhaust gas treatment method which can improve an effect of inhibiting a reaction product from adhering to the inside of a gas outlet port of a dry pump or a gas exhaust pipe and can also improve an energy saving effect. To attain the object, the present invention is achieved by introducing, in the dry pump which sucks in a gas exhausted from a process chamber, a diluent gas heated using a heat generated from the dry pump into the gas from the process chamber that has been exhausted from the dry pump to dilute the gas from the process chamber.

Using <FIG>, the following will describe examples of an exhaust gas treatment apparatus in a semiconductor manufacturing treatment process
<FIG> is a block diagram showing a schematic overall configuration of an exhaust gas treatment apparatus. Using <FIG>, the following will describe the outline of the overall configuration of the exhaust gas treatment apparatus. The exhaust gas treatment apparatus is controlled in accordance with a procedure determined in advance by a program in a control device <NUM>. In a process chamber <NUM>, semiconductor wafers <NUM> are contained and each of a process gas for process treatment and a cleaning gas for cleaning treatment is supplied into the process chamber <NUM> through a gas supply pipe <NUM>. To the process chamber <NUM>, a dry pump <NUM> is connected via a gas exhaust pipe <NUM>. The process chamber <NUM> is adapted to be depressurized to a high vacuum by driving the dry pump <NUM>.

That is, a process gas such as, e.g., silane (SiH<NUM>) and a cleaning gas such as chlorine trifluoride (ClF<NUM>), nitrogen trifluoride (NF<NUM>), or hydrogen chloride (HCl) which have been used for treatment in the foregoing process chamber <NUM> (such a process gas and a cleaning gas will be hereinafter generally referred to as "used gas G1") pass through the gas exhaust pipe <NUM> to be introduced into the downstream dry pump <NUM>. The dry pump <NUM> sucks in the used gas G1 from the process chamber <NUM> through a gas inlet port 17a and gradually pressurizes the used gas G1 in, e.g., six stages therein. The used gas G1 pressurized to a pressure in the vicinity of an atmospheric pressure in the dry pump <NUM> is exhausted from a gas outlet port 17b into a gas exhaust pipe <NUM> and transmitted from the gas exhaust pipe <NUM> to a detoxification device <NUM>. After detoxified in the detoxification device <NUM>, the used gas G1 is exhausted into atmospheric air. Accordingly, the gas exhaust pipe <NUM> has one end connected to the gas outlet port 17b of the dry pump <NUM> and the other end connected to a gas inlet port 19a of the detoxification device <NUM>.

To the foregoing dry pump <NUM>, a heat exchanger <NUM> as heating means is attached. Into the heat exchanger <NUM>, a diluent gas G2 is caused to flow through a diluent gas pipe <NUM>. The diluent gas G2 heated by the heat exchanger <NUM> is introduced from a diluent gas feed port 18a provided in the middle of the gas exhaust pipe <NUM> into the gas exhaust pipe <NUM>, mixed with the used gas G1 from the dry pump <NUM>, and introduced into the detoxification device <NUM>. Note that, in the present example, the diluent gas G2 is, e.g., a nitrogen (N<NUM>) gas. The position where the diluent gas feed port 18a is to be provided is arbitrarily set between the gas outlet port 17b and the gas inlet port 19a of the detoxification device <NUM>. The diluent gas feed port 18a allows the foregoing diluent gas G2 to flow from any set position into the gas exhaust pipe <NUM>.

<FIG> is a schematic side cross-sectional view schematically showing an inner structure of the dry pump <NUM>. The dry pump <NUM> shown in <FIG> includes a pump casing <NUM> having a plurality of (six in the present example) pump chambers 22a, 22b, 22c, 22d, 22e, and 22f, rotors 24a, 24b, 24c, 24d, 24e, and 24f disposed in the respective pump chambers 22a to 22f, a pair of rotation shafts 25a and 25b each having the rotors 24a to 24f integrally fixed thereto to integrally rotate the rotors 24a to 24f, a pair of gears 26a and 26b for rotating the pair of rotation shafts 25a and 25b in synchronization, a motor <NUM> as a rotation driving mechanism for rotating the rotation shafts 25a and 25b via the pair of gears 26a and 26b, and bearing pairs 28a and 28b which support the rotation shafts 25a and 25b relative to a pump casing <NUM>.

The foregoing pump casing <NUM> is formed by successively arranging a plurality of stators 23a in multiple layers in an axial direction in consideration of assemblability, though not shown. The foregoing pump casing <NUM> is also formed such that, as shown in <FIG>, a cross section thereof perpendicular to the rotation shafts 25a and 25b has a generally rectangular shape. On an outer peripheral surface <NUM> of the pump casing <NUM>, the foregoing heat exchanger <NUM> for performing heat exchange with the dry pump <NUM> is disposed.

As shown in <FIG> and <FIG>, the foregoing heat exchanger <NUM> includes a heat exchanger casing 20a disposed on with being in firm contact with the outer peripheral surface <NUM> of the pump casing <NUM> and formed of a material (e.g., an aluminum material) having an excellent heat conductivity and a gas pipe 20c formed of a material (e.g., a copper material) similarly having an excellent heat conductivity. The heat exchanger casing 20a has a guide groove 20b which is opened in an outer side surface thereof to have a U-shaped cross-sectional shape and bent in a zigzag pattern. In the guide groove 20b bent in the zigzag pattern, the foregoing gas pipe 20c is disposed to be also bent in the zigzag pattern similarly to the guide groove 20b.

The gas pipe 20c originally has a circular cross-sectional shape. The gas pipe 20c having the circular cross-sectional is disposed in the guide groove 20b, as shown in, e.g., <FIG>, and pressed from the outside thereof to be deformed. Thus, as shown in <FIG> and <FIG>, the gas pipe 20c is brought into firm contact with three inner surfaces of the guide groove 20b to be formed into the gas pipe 20c having a rectangular cross section. As a result, the heat exchanger casing 20a and the gas pipe 20c are integrated with each other in the guide groove 20b to allow heat exchange to be efficiently performed between the heat exchanger casing 20a and the gas pipe 20c.

In the heat exchanger <NUM> thus formed, when the foregoing diluent gas pipe <NUM> is connected to each of the inlet and outlet of the gas pipe 20c and the diluent gas G2 is caused to flow in the diluent gas pipe <NUM>, the diluent gas G2 passes through the diluent gas pipe <NUM> and the heat exchanger <NUM> to enter the gas exhaust pipe <NUM> from a point in the middle of the gas exhaust pipe <NUM>, i.e., from the diluent gas feed port 18a between the dry pump <NUM> and the detoxification device <NUM>. Thus, the diluent gas G2 can be mixed with the used gas G1 from the dry pump <NUM> and introduced into the detoxification device <NUM>. Note that, to a point in the middle of the diluent gas pipe <NUM>, an open/close valve <NUM> is attached and the open/close control of the open/close valve <NUM> is performed under the control of the control device <NUM>. That is, when the open/close valve <NUM> is open, the diluent gas G2 heated by the heat exchanger <NUM> is allowed to enter the gas exhaust pipe <NUM> from the diluent gas feed port 18a.

Since the heat exchanger <NUM> has the heat exchanger casing 20a disposed on with being in firm contact with the pump casing <NUM>, during the operation of the dry pump <NUM>, the heat exchanger casing 20a and the gas pipe 20c are heated to generally the same temperatures (<NUM> to <NUM> in the present example) as the pump casing <NUM>. Consequently, the diluent gas G2 transmitted to the heat exchanger <NUM> through the diluent gas pipe <NUM> is heated by the heat from the gas pipe 20c to a temperature in the vicinity of <NUM> to <NUM>, while passing through the gas pipe 20c of the heat exchanger <NUM>. The heated diluent gas G2 is caused to flow from the diluent gas feed port 18a provided in the middle of the gas exhaust pipe <NUM> into the gas exhaust pipe <NUM> and mixed with the used gas G1 from the dry pump <NUM>. Thus, the used gas G1 can be heated to a temperature in the vicinity of <NUM> to <NUM> and fed into the detoxification device <NUM>. Therefore, to allow the heated gas mixture (G1 and G2) to be introduced into the detoxification device <NUM> while retaining a high temperature, the diluent gas pipe <NUM> and the gas exhaust pipe <NUM> are preferably connected at a position immediately before and as close as possible to the detoxification device <NUM>.

Next, the function of the exhaust gas treatment apparatus thus configured will be described. First, when the dry pump <NUM> is activated under the control of the control device <NUM>, the motor <NUM> is also driven to rotate the rotation shaft 25a. At this time, the rotation shaft 25b arranged in parallel with the rotation shaft 25a is rotated in synchronization by engagement of the gears 26a and 26b with each other. The rotation shaft 25b rotates in a direction opposite to the direction of rotation of the rotation shaft 25a.

By the rotation of the rotation shafts 25a and 25b, the rotors 24a to 24f integrally fixed to the rotation shaft 25a and the rotors 24a to 24f integrally fixed to the rotation shaft 25b rotate in opposite directions in the respective pump chambers 22a to 22f. Note that the rotors 24a to 24f attached to the rotation shaft 25a and the rotors 24a to 24f attached to the rotation shaft 25b are cocoon-shaped root rotors which rotate in synchronization, while maintaining <NUM>° phase differences and minute gaps therebetween in non-contact relation.

As a result, from the gas inlet port 17a communicating with a target space to be evacuated, the used gas G1 is sucked into the first stage pump chamber 22a. Then, the used gas G1 is successively sucked from the first stage pump chamber 22a into the second stage pump chamber 22b, from the second stage pump chamber 22b into the third stage pump chamber 22c, from the third stage pump chamber 22c into the fourth stage pump chamber 22d, and from the fourth stage pump chamber 22d into the fifth stage pump chamber 22e. Finally, the used gas G1 is exhausted from the dry pump <NUM> via the gas exhaust pipe <NUM> communicating with the gas outlet port 17b of the sixth stage pump chamber 22f to bring the target space to be evacuated into a vacuum state.

At this time, the used gas G1 is exhausted, while being compressed in each of the pump chambers 22a, 22b, 22c, 22d, 22e, and 22f. As a result, the temperature of the used gas G1 increases to also increase the temperature of the pump casing <NUM>. Note that, among the pump chambers 22a, 22b, 22c, 22d, 22e, 22f, the sixth stage pump chamber 22f is highest in the temperature of the used gas G1 at an outlet side. The sixth stage pump chamber 22f has a large pressure difference between the used gas G1 at an inlet side and the used gas G1 at the outlet side. At the outlet side of the sixth stage pump chamber 22f, the used gas G1 is heated to a relatively high temperature in a range of, e.g., about <NUM> to <NUM>.

The used gas G1 exhausted from the sixth stage pump chamber 22f flows toward the detoxification device <NUM> several meters away through the gas exhaust pipe <NUM>. Note that, when mixed with the diluent gas G2 at a temperature lower than that of the heated used gas G1 mentioned above, the used gas G1 may be cooled. However, in the case of the structure in the present example, the diluent gas G2 heated to a temperature in the vicinity of <NUM> to <NUM> while passing through the heat exchanger <NUM> as the heating means is introduced into the gas outlet port 17b or into the gas exhaust pipe <NUM> from the diluent gas feed port 18a provided in the middle of the gas exhaust pipe <NUM>. The diluent gas G2 is mixed with the used gas G1 from the dry pump <NUM> to heat the used gas G1 again to a high temperature in the vicinity of <NUM> to <NUM> and feed the heated used gas G1 into the detoxification device <NUM>. As a result, the used gas G1 which is about to be condensed is heated again to a high temperature to be vaporized and introduced together with the diluent gas G2 into the detoxification device <NUM>.

Accordingly, with this configuration, it is possible to eliminate a reaction product deposited in the gas outlet port 17b or in the gas exhaust pipe <NUM> and the detoxification device <NUM> and prevent the pipe from being clogged. In addition, the used gas G1 and the diluent gas G2 that have been introduced into the detoxification device <NUM> are detoxified in the detoxification device <NUM> and then smoothly exhausted therefrom into atmospheric air. Moreover, the heat exchanger <NUM> as the heating means uses the heat generated from the dry pump <NUM> as a heat source and does not use an electrically heated wire as used in a conventional device. This can eliminate power consumption and contribute to energy saving.

<FIG> and <FIG> show a the dry pump according to the present invention. <FIG> is a schematic side cross-sectional view schematically showing an inner structure of a dry pump <NUM>. <FIG> is a cross-sectional view along the line B-B in <FIG>. In the example shown in <FIG>, the heat exchanger <NUM> is attached to the outside of the pump casing <NUM> and the diluent gas G2 is caused to flow in the heat exchanger <NUM>. By contrast, the dry pump <NUM> of the present example, is configured such that a sealing gas G3 is caused to flow in a sealing gas flow path <NUM> formed of sealing gas grooves 33a provided in the pump casing <NUM> such that the sealing gas G3 is heated with the heat generated in the pump casing <NUM> to be used as a diluent gas. Accordingly, in the following description, the same components as those of the dry pump <NUM> in the example shown in <FIG> are designated by the same reference numerals and a description thereof is omitted. A description will be given only of a portion with a different structure.

In <FIG> and <FIG>, in respective facing surfaces of the plurality of stators 23a arranged in multiple layers in an axial direction to form the pump casing <NUM>, the sealing gas grooves 33a are formed so as to externally surround the respective pump chambers 22d to 22f. During the formation of the pump casing <NUM>, when the individual stators 23a are arranged in multiple layers and assembled, in respective portions forming the individual pump chambers 22d to 22f, the sealing gas grooves 33a face each other to form the sealing gas flow path <NUM> in which the sealing gas G3 flows. In the case described in the present example, the respective sealing gas grooves 33a are formed in both side surfaces of each of the stators 23a. However, it may also be possible that the sealing gas groove 33a is formed only in one side surface of each of the stators 23a. Note that, during the assembly of the pump casing <NUM>, between the individual pump chambers 22a to 22f and the stators 23a, O-rings <NUM> are disposed tightly in O-ring grooves <NUM> so as to externally surround the respective pump chambers 22d to 22f and maintain hermetic sealing of the pump chambers 22a to 22f, as shown in <FIG>.

Since the O-rings <NUM> are corroded by the foregoing used gas G1, in the dry pump <NUM> in the present example, a N<NUM> gas as inert gas is introduced into the sealing gas flow path <NUM> to prevent the corrosion. The respective pressures in the first to sixth stage pump chambers 22a to 22f are progressively higher in order of increasing "stage" number. Accordingly, in the dry pump <NUM> in the present example, the N<NUM> gas as the sealing gas G3 is caused to flow (introduced) into the each of the fourth, fifth, and sixth stage pump chambers 22d to 22f having the higher "stage" numbers. This is intended to prevent sealing performance from deteriorating as the O-rings <NUM> are more likely to be corroded due to the compression/condensation of the corrosive used gas G1 in the pump chambers 22d to 22f having the progressively higher pressures and to contribute to the sealing performance in association with the O-rings <NUM>. Note that, to simplify the structure of the dry pump <NUM>, the pump chamber into which the sealing gas G3 is caused to flow may also be only a final pump chamber (sixth stage pump chamber) 22f having the highest pressure.

Accordingly, in the dry pump <NUM> of the present example, the sealing gas groove 33a in each of the stators 23a forming the fourth, fifth, and sixth stage pump chambers 22d to 22f is provided with a sealing gas inlet port 36b of a sealing gas feed path <NUM> and with a sealing gas outlet port 37b of a sealing gas exhaust path <NUM>. The sealing gas feed path <NUM> has a sealing-gas-feed-pipe connection port 36a provided in an outer surface (outer surface <NUM> of the pump casing <NUM>) of the stator 23a. The sealing gas exhaust path <NUM> has a sealing-gas-exhaust-pipe connection port 37a similarly provided in the outer surface of the stator 23a. To each of the sealing-gas-feed-pipe connection ports 36a, a sealing gas feed pipe <NUM> into which the sealing gas G3 is supplied is connected via a control valve <NUM>. To each of the sealing-gas-exhaust-pipe connection ports 37a, a sealing gas exhaust pipe <NUM> into which the sealing gas G3 is exhausted is connected via a control valve <NUM>. The sealing gas exhaust pipe <NUM> is also connected to the gas exhaust pipe <NUM> via the diluent gas feed port 18a. Note that, as the control valves <NUM> and <NUM>, control valves each capable of controlling, e.g., a gas flow rate may be used appropriately.

In the dry pump <NUM> thus configured, when the sealing gas G3 is fed from the sealing gas feed pipe <NUM>, the sealing gas G3 passes through the sealing gas feed paths <NUM> to enter the sealing gas flow path <NUM> formed in the pump casing <NUM>. After flowing in the sealing gas flow path <NUM>, the sealing gas G3 passes from the sealing gas outlet ports 37b through the sealing gas exhaust paths <NUM> to be exhausted into the sealing gas exhaust pipe <NUM>. The sealing gas G3 is then transmitted into the gas exhaust pipe <NUM> via the gas outlet port 17b or the diluent gas feed port 18a to be mixed with the used gas G1.

Note that the supply and exhaust of the sealing gas G3 to each of the pump chambers 22d to 22f can be adjusted individually using the control valve <NUM> or <NUM>. That is, when a large amount of the sealing gas G3 is caused to flow at a time into the pump chambers 22d to 22f, the exhaust performance of the dry pump <NUM> may be affected thereby. Accordingly, the sealing gas G3 is not introduced into all the pump chambers 22d to 22f at a time. The flow of the sealing gas G3 is adjusted using the control valve <NUM> or <NUM> such that, depending on the situation, the sealing gas G3 is caused to flow at a flow rate which does not affect the exhaust performance of the dry pump <NUM>, into each of the pump chambers 22d to 22f. In general, the flow rate of a diluent gas required for dilution in the gas outlet port 17b or the gas exhaust pipe <NUM> is higher than the flow rate of a gas required for sealing using an O-ring. This configuration allows a gas to flow in the sealing gas flow path <NUM> at a flow rate necessary and sufficient for dilution in the gas outlet port 17b or the gas exhaust pipe <NUM>, without affecting the exhaust performance of the dry pump <NUM>.

As a result, when the sealing gas flow path <NUM> of the dry pump <NUM> is used, the sealing gas G3 passing through the pump casing <NUM> is heated to a relatively high temperature of, e.g., about <NUM> to <NUM> by the pump casing <NUM> having an increased temperature. The sealing gas G3 is then transmitted into the gas exhaust pipe <NUM> and mixed with the used gas G1. Thus, the sealing gas can be fed into the detoxification device <NUM> in the same manner as in the example provided in <FIG>. Thus, reusing the sealing gas G3 for preventing the corrosion of the respective O-rings <NUM> in the pump chambers 22d to 22f as the diluent gas, it is possible to eliminate a reaction product deposited in the gas outlet port 17b or in the gas exhaust pipe <NUM> and the detoxification device <NUM> and prevent the pipe from being clogged. In addition, the used gas G1 and the diluent gas G2 that have been introduced into the detoxification device <NUM> are detoxified in the detoxification device <NUM> and then smoothly exhausted into atmospheric air. Moreover, as the heat source used herein, the heat generated from the dry pump <NUM> is used, but an electrically heated wire as used in a conventional device is not used. This can eliminate power consumption and contribute to energy saving.

Note that, as shown in <FIG>, each of the sealing gas outlet ports 37b which exhaust the sealing gas G3 to the outside of the dry pump <NUM> is preferably disposed in an upstream of the sealing gas inlet port <NUM> through which the sealing gas G3 is introduced into each of the pump chambers 22d to 22f. This allows the amount of the sealing gas G3 flowing into each of the pump chambers 22d to 22f to be easily controlled by providing the control valve <NUM> at the outlet side.

The structure of <FIG> and the structure of <FIG> can also be combined with each other as necessary.

In the case disclosed in each of the foregoing examples, only the heat generated from the dry pump <NUM> or <NUM> is used as a heat source. However, as necessary, an electrically heated wire may also be used in combination. In that case also, it is possible to significantly reduce power consumption used by the electrically heated wire and contribute to energy saving.

Claim 1:
A dry pump (<NUM>) for sucking in a gas (G1) exhausted from a process chamber (<NUM>), said dry pump comprising:
a casing (<NUM>) formed by a plurality of stators arranged in an axial direction,
pump chambers (22a, 22b, 22c, 22d, 22e, 22f) formed by the respective stators,
a diluent gas feed pipe (<NUM>) and a diluent gas exhaust pipe (<NUM>) provided in the outer surface of at least one stator,
the diluent gas exhaust pipe (<NUM>) is connected to a diluent gas introduction inlet (18a) provided in either a gas outlet port (17b) of the dry pump or a gas exhaust pipe (<NUM>) connected to the gas outlet port,
wherein said dry pump is configured to receive a diluent gas (G3) from said feed pipe (<NUM>) into a stator of the dry pump, for, in use, heating said diluent gas prior to transmission to the diluent gas exhaust pipe (<NUM>), and wherein
a flow path (<NUM>) of the diluent gas in at least one stator of said casing is configured to externally surround the pump chamber (22a, 22b, 22c, 22d, 22e, 22f) of the stator, each flow path (<NUM>) is provided with a diluent gas inlet port (36b) of a diluent gas feed path (<NUM>) and with a diluent gas outlet port (37b) of a diluent gas exhaust path (<NUM>); wherein, when the diluent gas (G3) is fed from said feed pipe (<NUM>), the diluent gas (G3) passes through the diluent gas feed path (<NUM>) to pass from the diluent gas inlet port (36b) through the flow path (<NUM>), before passing from the diluent gas outlet port (37b) through the diluent gas exhaust path (<NUM>) to be exhausted into the diluent gas exhaust pipe (<NUM>),
the dry pump being characterised in that it further comprises
valves (<NUM>, <NUM>), which are arranged respectively in the diluent gas feed path (<NUM>) and the diluent gas exhaust path (<NUM>) and are arranged to adjust the supply and exhaust of the diluent gas to each of the stators.