TWI467092B - Vacuum pumping device - Google Patents

Description

Vacuum exhaust

The present invention relates to a vacuum exhaust apparatus in which an auxiliary pump is connected in series to a main pump, and more particularly to a vacuum exhaust apparatus which can improve an exhaust speed.

The present application claims priority on Japanese Patent Application No. 2008-232324, filed on Sep.

As one of the prior vacuum evacuation devices for exhausting to medium vacuum, a mechanical booster pump (hereinafter referred to as MBP) functioning as a main pump and a dry vacuum pump connected as an auxiliary pump have been connected in series (for example, Patent Document 1).

In such a vacuum exhaust device, since the target vacuum degree is the main target, the exhaust amount of the MBP in the first stage is set to be larger than the DRP amount in the second stage. Specifically, the displacement of the main pump is set to be 5 to 10 times the displacement of the auxiliary pump. Thereby, in the medium vacuum region, the exhaust performance of the MBP can be fully utilized by the auxiliary exhaust of the DRP.

In addition, in the vacuum evacuation device, when the vacuum chamber of the atmospheric pressure vacuum chamber is started, the gate valve provided in the middle of the vacuum chamber and the suction pipe of the MBP is opened, but the vacuum chamber is instantaneously generated. The pressure will spread as a shock wave and cause an impact on the MBP. Therefore, it is required for MBP to have the strength of a machine that can withstand the impact.

As an example of the prior art for mitigating the transient impact when the vacuum chamber is opened, a groove such as a buffer tank is disposed in the middle of the piping between the MBP and the DRP for releasing the impact pressure and mitigating the transient pressure. The component of the change (for example, refer to Patent Document 1).

Further, as another example of the prior art for mitigating the transitional impact, there is provided a bypass pipe for returning from the exhaust side of the main pump to the intake side of the main pump, or provided for A gas having a pressure higher than a specific pressure is supplied from the exhaust side of the main pump to the bypass side of the exhaust side of the auxiliary pump (see, for example, Patent Document 1).

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2007-127048

For example, in the loading chamber of the liquid crystal manufacturing apparatus (hereinafter referred to as LC), when the vacuum exhausting device is used to repeatedly exhaust the air from the atmospheric pressure to the medium vacuum region, in order to improve the productivity, the arrival time of the target vacuum degree is One of the indicators of performance. Therefore, in the vacuum evacuation device, the medium vacuum region is self-evident, and the decompression region in the low vacuum region and the vicinity of the atmosphere is also required to have high exhaust gas characteristics.

However, MBP and DRP are arranged in series, and in the above-mentioned prior vacuum exhaust apparatus in which the exhaust capacity of the initial stage MBP is greater than the exhaust capacity of the DRP of the second stage, the gas discharged from the MBP must pass through the DRP. Therefore, in the decompression zone and the low vacuum zone near atmospheric pressure, the exhaust performance of the MBP is restricted by the exhaust performance of the DRP, and the exhaust pressure of the MBP is higher than the intake pressure. As a result, MBP performs unnecessary compression work and its number of revolutions decreases significantly. As a result, the effect of MBP as a blower cannot be fully exerted.

The present invention has been developed to solve the above-mentioned problems, and an object thereof is to provide a vacuum discharge which can shorten the exhaust time to reach a target degree of vacuum without greatly changing the structure of the main pump and the auxiliary pump. Gas device.

The present invention employs the following means to achieve the above objects. That is, a vacuum exhaust apparatus according to an aspect of the present invention includes: a main pump; an auxiliary pump connected in series with the main pump; and an exhaust port connecting the main pump and an intake port of the auxiliary pump The pump is connected between the pumps; and the main pump includes a mechanical booster pump; the ratio of the maximum power of the motor of the main pump to the maximum exhaust velocity of the main pump is 5 W/(m ³ /h) or more; There is a branch pipe that is different from the middle of the pipe, and a check valve that allows the gas in the pipe between the pumps to escape and prevent it from flowing back is provided in the middle of the above-mentioned branch pipe.

The main pump may also include a plurality of the above-described mechanical booster pumps arranged in parallel.

Further, the branch pipe may be connected to the exhaust pipe of the auxiliary pump at the end.

Further, when the main pump is operated at atmospheric pressure, the pressure loss of the gas flow rate of the check valve is preferably 10000 Pa or less.

According to the above aspect of the present invention, by setting the motor of the main pump to a large output power and providing a check valve and a branch pipe, the exhaust speed of the main pump is not blocked by the auxiliary pump even near atmospheric pressure. The gas velocity is restricted so that the exhaust velocity in the vicinity of the atmospheric pressure and in the low vacuum region can be increased. As a result, the exhaust time to reach the target degree of vacuum can be shortened without significantly changing the structure of the main pump and the auxiliary pump.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It is to be understood that the invention is not limited thereto, and various modifications may be made without departing from the spirit and scope of the invention.

[Embodiment 1]

Fig. 1 is a schematic view showing the configuration of a vacuum exhausting apparatus according to a first embodiment of the present invention. The vacuum exhaust apparatus 100 of the first embodiment includes a main pump 1, an auxiliary pump 2, and a check valve 3.

The vacuum chamber 20 is, for example, a processing chamber or a transfer chamber that constitutes a semiconductor manufacturing device, and is evacuated by the vacuum exhaust device 100. Here, the vacuum chamber 20 is a loading vacuum chamber of a liquid crystal manufacturing apparatus (hereinafter referred to as LC).

The gate valve 30 is provided in the middle of a pipe (suction pipe) 40 that connects the exhaust port of the LC 20 and the intake port of the MBP 1. The gate valve 30 is opened when the LC 20 that is open to atmospheric pressure is started to be exhausted by the vacuum exhaust device, and is closed when the vacuum exhausted LC 20 is opened to atmospheric pressure.

In the vacuum exhaust apparatus 100, the main pump 1 and the auxiliary pump 2 are connected in series by a piping (pump piping) 50 that connects the exhaust port of the main pump 1 and the intake port of the auxiliary pump 2. The exhaust port of the auxiliary pump 2 is connected by a pipe (exhaust pipe) 60.

As described above, in the vacuum exhaust apparatus 100, the main pump 1 and the auxiliary pump 2 are connected in series. Further, the pump of the first stage directly connected to the exhaust port of the LC 20 via the gate valve 30 is the main pump, and the pump of the second stage disposed on the exhaust port side of the main pump is the auxiliary pump. Here, the main pump 1 is a mechanical booster pump (hereinafter referred to as MBP). Further, the auxiliary pump 2 is a dry vacuum pump (hereinafter referred to as DRP). Furthermore, the main pump 1 is not limited to being constituted by one (1 segment) MBP, and may be constituted by two stages of MBP called a multi-function booster pump, or by a plurality of MBPs. .

MBP1 is a pump that increases the output power of its motor without changing the pump unit in the MBP that constitutes the previous vacuum exhaust unit. The ratio of the maximum power (unit: W) of the above-mentioned motor of the MBP of the previous device to the maximum exhaust velocity (unit: m ³ /h) is less than 5 W/(m ³ /h) (for example, 10000 (W) / 3600 ( m ³ /h)=2.77), but in the MBP1 of the present embodiment, the above ratio is 5 W/(m ³ /h) or more (for example, 30,000 (W) / 3600 (m ³ /h) = 8.33). Furthermore, the exhaust velocity of the MBP is maximized in the medium vacuum region (for example, when the intake pressure is 13 Pa).

In addition, the vacuum exhaust apparatus 100 is provided with a pipe (dividing pipe) 70 that is branched from the pump pipe 50 and is connected to the exhaust pipe 60 of the DRP 2. A check valve 3 is provided in the middle of the pipe 70.

When the pressure in the pump pipe 50 becomes higher than the pressure in the exhaust pipe 60, the gas in the pump pipe 50 can escape to the exhaust pipe 60, and the gas in the exhaust pipe 60 can be prevented. Countercurrent to the pump piping 50. The check valve 3 preferably has a sufficient capacity that does not cause a pressure loss even when the MBP1 is operated at atmospheric pressure. For example, when the MBP1 is operated at atmospheric pressure, the pressure loss of the gas flow rate of the check valve 3 at atmospheric pressure is preferably 10000 Pa or less.

According to the vacuum exhaust apparatus of the present embodiment, the exhaust performance in the low vacuum region can be improved by using the MBP1 of the motor having a large output. Since it is not necessary to use MBP for compression near atmospheric pressure, the exhaust velocity of the MBP monomer is greater than the exhaust velocity of the DRP monomer. However, in the structure in which the MBP and the DRP are connected in series, the exhaust pressure of the MBP is higher than the intake pressure in the vicinity of the atmospheric pressure and the low vacuum region, so the exhaust velocity of the MBP is restricted by the exhaust velocity of the DRP, and the MBP is made. The number of revolutions has dropped. By setting the motor of the MBP1 as a large output power motor, it is possible to suppress the decrease in the number of revolutions in the low vacuum region and to improve the exhaust speed.

Further, in the vacuum evacuation device of the present embodiment, the check valve 3 and the branch pipe 70 are provided, so that the exhaust gas characteristics in the vicinity of the atmospheric pressure can be improved. By arranging the check valve 3 having a small pressure loss, when the exhaust pressure of the MBP1 (the pressure in the pump piping 50) rises in the low vacuum region and the atmospheric pressure, the gas in the pump pipe 50 escapes to the discharge. The gas piping 60 can suppress the exhaust pressure of MBP1. Thereby, MBP1 can be effectively utilized as a blower, and as a result, it is not restricted by the exhaust performance of DRP2. The smaller the pressure loss of the check valve 3, the more pronounced the effect.

As described above, in the vacuum exhaust apparatus of the present embodiment, by using the MBP1 of the motor having a large output power and providing the check valve 3 and the branch pipe 7, the exhaust speed in the low vacuum region and the atmospheric pressure can be improved. As a result, the exhaust time of the LC 20 can be shortened.

Further, by providing the check valve 3 and the branch pipe 70, when the gate valve 30 is opened to evacuate the vacuum of the LC20 at atmospheric pressure, the pressure shock wave originating from the LC 20 escapes through the check valve 3, so that the pressure can be alleviated. The impact of MBP1. Therefore, MBP1 is not easily restricted by the strength design, and the durability of MBP1 can be further improved.

Fig. 2 is a schematic view showing the structure of a vacuum exhausting apparatus of Comparative Example 1, and the same members as those in Fig. 1 are denoted by the same reference numerals. In the vacuum exhaust apparatus 101 of Comparative Example 1, MBP11 and DRP2 are arranged in series. The MBP 11 has the same pump unit as the MBP1 of the first embodiment, and a motor having a lower output power than the MBP1. That is, the ratio of the maximum power (unit: W) of the motor of the MBP 11 to the maximum exhaust speed is less than 5 W/(m3/h).

Fig. 3 is a schematic view showing the structure of a vacuum exhausting apparatus of Comparative Example 2, and the same members as those in Fig. 1 are denoted by the same reference numerals. In the vacuum exhaust apparatus 102 of Comparative Example 2, MBP1 and DRP2 are arranged in series. In other words, the vacuum exhaust device 102 of the second embodiment is configured such that the check valve 3 and the branch pipe 70 are not provided in the vacuum exhaust device 100 (see FIG. 1) of the first embodiment, and the vacuum exhaust gas of the comparative example 1 is used. In the device 101 (see FIG. 2), the MBP 11 is changed to MBP1.

4A and 4B are views showing the exhaust characteristics of the vacuum exhaust apparatus according to the first embodiment and the comparative examples 1 and 2 of the present invention. Specifically, FIG. 4A is an exhaust gas velocity characteristic (exhaust performance) of the DRP2 monomer and the vacuum exhaust apparatus of the first embodiment and the first and second comparative examples, and FIG. 4B is an LC20 of the first embodiment and the comparative examples 1 and 2. Pressure characteristics (pressure transition of LC20). In FIGS. 4A and 4B, A is an atmospheric pressure A1, a pressure reduction region near the atmospheric pressure (a region near atmospheric pressure), a B-system low vacuum region, and a C-system vacuum region. Further, a1 indicates the characteristics of the DRP2 monomer, b1 and b2 indicate the characteristics of the vacuum exhaust device 101 of Comparative Example 1, and c1 and c2 indicate the characteristics of the vacuum exhaust device 102 of Comparative Example 2, and d1 and d2 are The characteristics of the vacuum exhaust apparatus 100 of the first embodiment are shown.

For example, the region A is in the range of 101,300 Pa (atmospheric pressure A1) to 30,000 Pa, the low vacuum region B is in the range of 30,000 Pa to 1,330 Pa, and the medium vacuum region C is in the range of 1,330 Pa or less.

As shown in the characteristic curve a1 of FIG. 4A, the exhaust velocity of the DRP2 unit is substantially fixed in the region A and the low vacuum region B in the vicinity of the atmospheric pressure, and remains fixed even if it further enters the medium vacuum region C, but reaches the vacuum as the target is approached. The degree is gradually decreasing.

Further, as shown by the characteristic curve b1 of FIG. 4A, the exhaust velocity of the vacuum exhaust apparatus 101 of Comparative Example 1 gradually increases as it passes from the region A near the atmospheric pressure to the intermediate vacuum region C through the low vacuum region B. Thereafter, the exhaust velocity of the vacuum exhaust device 101 is maximized in the middle vacuum region C near the boundary between the low vacuum region B and the target reaching the degree of vacuum, and decreases as the approaching target reaches the degree of vacuum.

As shown in the characteristic curve c1 of FIG. 4A, in Comparative Example 2 of the low vacuum region B, since MBP1 having a higher output power than that of MBP11 of Comparative Example 1 was used, the exhaust velocity was compared with that of Comparative Example 1. The situation (characteristic curve b1) has been improved. However, since the exhaust performance of MBP1 is restricted by the exhaust performance of DRP2 in the region A near atmospheric pressure, the exhaust velocity of Comparative Example 2 is improved as compared with Comparative Example 1, but the MBP1 cannot be fully utilized. Exhaust capacity. Further, in Comparative Example 2 in the medium vacuum region C, since the pump portion was the same, the exhaust velocity characteristics were the same as those in Comparative Example 1.

On the other hand, as shown in the characteristic curve d1 of FIG. 4A, in the vacuum exhaust apparatus 100 of the first embodiment, the MBP1 having a higher output power than the MBP11 of the comparative example 1 is used in the low vacuum region B. The exhaust gas velocity was improved as compared with the above Comparative Example 1 (characteristic curve b1), and was equivalent to the case of Comparative Example 2 (characteristic curve c1). Further, since the vacuum exhaust device 100 of the first embodiment is provided with the check valve 3 and the branch pipe 70, the exhaust performance of the MBP 1 is not restricted by the exhaust performance of the DRP 2. Therefore, the exhaust performance in the region A near the atmospheric pressure in the present embodiment is improved as compared with the case of the comparative example 2 (characteristic curve c1).

Further, in the vacuum evacuation device 100 of the first embodiment in the low vacuum region B and the intermediate vacuum region C, since the MBP is the same, the exhaust velocity characteristics are the same as those in the comparative example 2.

As shown in FIG. 4B, the pressure transition of the LC 20 corresponds to the exhaust performance of the vacuum exhaust. Therefore, in the low vacuum region B and the medium vacuum region C, the characteristic curve c2 of Comparative Example 2 is parallel to the characteristic curve d2 of the vacuum exhaust device 100 of the first embodiment. Further, in the medium vacuum region C, the characteristic curve b2 of Comparative Example 1 and the characteristic curve c2 of Comparative Example 2 are parallel to the characteristic curve d2 of the vacuum exhaust apparatus 100 of the first embodiment.

Since the vacuum exhaust device 102 of Comparative Example 2 is superior to the vacuum exhaust device 101 of Comparative Example 1, the exhaust performance in the region A and the low vacuum region B in the vicinity of the atmospheric pressure and the atmospheric pressure is superior, so that the low vacuum region A is reached. The time until the arrival and the time to reach the medium vacuum area C are respectively short. Further, in the vacuum evacuation device 100 of the first embodiment, the evacuation performance in the region A near the atmospheric pressure is superior to that of the vacuum evacuation device 102 of the second embodiment, so that the time until reaching the low vacuum region B is short.

Therefore, among the vacuum exhaust device 100 of the first embodiment, the vacuum exhaust device 101 of the comparative example, and the vacuum exhaust device 102 of the comparative example, the vacuum exhaust device 100 of the first embodiment can be reached in the shortest time. The target vacuum is set in the medium vacuum region C. Further, in the vacuum evacuation device 102 of Comparative Example 2, the target vacuum degree can be reached in a shorter time than the vacuum evacuation device 101 of Comparative Example 1.

As described above, in the vacuum evacuation apparatus 100 of the first embodiment, the MBP11 of the comparative example 1 is used, and the output power MBP1 is higher. Therefore, in the low vacuum region B and the vicinity of the atmospheric pressure region A, comparison with the comparative example 1 can be realized. The higher the exhaust speed. Further, by providing the check valve 3 and the branch pipe 70, the exhaust gas velocity higher than that of the vacuum exhaust device 102 of Comparative Example 2 can be achieved in the region A near the atmospheric pressure.

Therefore, in the vacuum evacuation device 100 according to the first embodiment, the exhaust capability of the MBP 1 can be sufficiently exhibited in the low vacuum region B and the region A near the atmospheric pressure.

According to the vacuum exhaust apparatus 100 of the first embodiment described above, by setting the motor of the MBP1 to a large output and providing the check valve 3 and the branch pipe 70, the exhaust speed of the main pump is even in the vicinity of the atmospheric pressure. It is also unaffected by the exhaust velocity of the auxiliary pump, so that the exhaust velocity in the vicinity of the atmospheric pressure and in the low vacuum region can be increased. Therefore, on the one hand, the change in the structure of MBP1 and DRP2 can be minimized, and on the other hand, the exhaust performance in the region A near the atmospheric pressure and the low vacuum region B can be improved, and as a result, the LC 20 can be reached to the target vacuum in a short time. degree.

Further, in the first embodiment, the branch pipe 70 may not be connected to the exhaust pipe 60 of the DRP 2, and the branch pipe 70 may be used as an individual exhaust pipe.

[Embodiment 2]

Fig. 5 is a schematic view showing the structure of a vacuum exhausting apparatus according to a second embodiment of the present invention, and the same members as those in Fig. 1 are denoted by the same reference numerals. The vacuum exhaust apparatus 200 of the second embodiment includes a main pump 21 in which two pumps (MBP) 21a and 21b are arranged in parallel, an auxiliary pump 2, and a check valve 3. In the vacuum exhaust apparatus 200 of the second embodiment, the main pump 1 including one MBP is changed to two MBPs 21a arranged in parallel, and the vacuum exhaust apparatus 100 (see FIG. 1) of the first embodiment. 21b constitutes the person.

In the vacuum exhaust apparatus 200, since a plurality of pumps are arranged in parallel to constitute a main pump, the motor of each pump constituting the main pump can increase the capacity of the entire main pump even if it is not set to a high output.

That is, in the second embodiment, the ratio of the maximum power (unit: W) of the motor to the maximum exhaust velocity is less than 5 W/(m ³ /h), but a total of 5 W/(m ³ / is arranged in parallel. h) The above two MBPs realize the main pump 21 with high output power.

According to the vacuum exhaust apparatus 200 of the second embodiment, the main pump 21 having a high output power in which a plurality of MBPs are arranged in parallel is used, and in the same manner as in the first embodiment, the region A and the low vacuum region in the vicinity of the atmospheric pressure can be obtained. The exhaust performance of B is improved, and as a result, the LC20 can reach the target vacuum in a short time.

Further, three or more pumps may be arranged in parallel to constitute a main pump, or a plurality of auxiliary pumps may be arranged in parallel, or a plurality of main pumps and auxiliary pumps may be arranged in parallel. Further, piping and gate valves may be provided between the pump and each of the pumps constituting the main pump. Further, a check valve and a branch pipe may be provided for each of the pumps constituting the main pump.

[Industrial availability]

According to the present invention, it is possible to provide a vacuum exhausting apparatus which can minimize the structural change of the main pump and the auxiliary pump and can shorten the exhaust time to reach the target degree of vacuum.

1. . . Main pump (MBP)

2. . . Auxiliary pump (DRP)

3. . . Check valve

20. . . Vacuum chamber (LC)

twenty one. . . Main pump

21a, 21b. . . MBP

30. . . gate

40, 50, 60, 70. . . Piping

100,200. . . Vacuum exhaust

Fig. 1 is a schematic view showing the structure of a vacuum exhausting apparatus according to Embodiment 1 of the present invention;

Figure 2 is a schematic view showing the structure of a vacuum exhausting device of Comparative Example 1;

Figure 3 is a schematic view showing the structure of a vacuum exhausting device of Comparative Example 2;

4A is a view showing exhaust characteristics (exhaust performance) of a vacuum exhaust apparatus according to Embodiment 1 of the present invention and Comparative Examples 1 and 2;

4B is a view showing the pressure characteristics of the LC 20 of the first embodiment and the comparative examples 1 and 2 of the present invention;

Fig. 5 is a schematic view showing the configuration of a vacuum exhausting apparatus according to a second embodiment of the present invention.

1. . . Main pump (MBP)

2. . . Auxiliary pump (DRP)

3. . . Check valve

20. . . Vacuum chamber (LC)

30. . . gate

40, 50, 60, 70. . . Piping

100. . . Vacuum exhaust

Claims (4)

A vacuum exhausting device comprising: a main pump; an auxiliary pump connected in series with the main pump; and an inter-pump piping connecting an exhaust port of the main pump and an intake port of the auxiliary pump; The main pump includes a mechanical booster pump; the ratio of the maximum power of the motor of the main pump to the maximum exhaust speed of the main pump is 5 W/(m ³ /h) or more; in the piping between the pumps, the middle of the pump is provided In the middle of the above-mentioned divergent piping, a check valve for allowing the gas in the piping between the pumps to escape and preventing it from flowing backward is provided. A vacuum exhaust apparatus according to claim 1 above, wherein said main pump comprises a plurality of said mechanical booster pumps arranged in parallel. A vacuum exhausting apparatus according to claim 1, wherein said branching system is terminated to an exhaust pipe of said auxiliary pump. The vacuum exhausting apparatus according to any one of claims 1 to 3, wherein, when the main pump is operated at atmospheric pressure, the pressure loss of the gas flow rate of the check valve is 10000 Pa or less.