JP2004044629A - Positioning device and countervailing method coping with its irregularities - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positioning device and a method for coping with its irregularities capable of avoiding or lessening the influence of its irregularities even though any trouble occurrs in a source of exhaust. <P>SOLUTION: When any irregularity occurrs in an exhaust pump P2, a pipe 14 is blocked with a valve V2 before fluid sucking powers of the exhaust pump P2 are completely lost. Therefore, external air is not entered into a differential pressure chamber 11c through the pipe 14 even though the positioning device is exposed to external air via the exhaust pump 2. A drastic decrease of sealing performance of a differential exhaust seal is effectively controlled accordingly. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a positioning device capable of moving a work in a room isolated from an external environment, for example, and a method applicable to an abnormal condition thereof.
[0002]
[Prior art]
2. Description of the Related Art In a semiconductor manufacturing apparatus and the like, a work is performed by mounting and moving a work on a stage in a process chamber maintained in a vacuum or a special gas atmosphere. Here, when the positioning device is provided in the process chamber, there is a possibility that lubricant or the like supplied to the movable portion may scatter and contaminate the process chamber.
[0003]
To address this problem, for example, U.S. Pat. No. 4,191,385 discloses an integrated negative pressure sealed gas bearing assembly. In such a conventional technique, a movable portion movable in a two-dimensional direction is provided on a bearing block, a process chamber is formed between the bearing block and the movable portion, and the process chamber and the outside are sealed by a differential exhaust seal. By doing so, it is possible to process a workpiece placed on a movable part inside the process chamber while maintaining the process chamber in a negative pressure environment. Therefore, the drive unit for driving the work can be installed outside the process chamber, whereby the contamination of the process chamber can be suppressed, and the drive unit can be easily maintained.
[0004]
[Problems to be solved by the invention]
By the way, in such a configuration, if any trouble occurs in an exhaust pump or a pipe for operating the differential exhaust seal, a problem such as an increase in the atmospheric pressure due to the intrusion of the atmosphere into the process chamber occurs, and May be defective.
[0005]
Therefore, the present invention has been made in view of the problems of the related art, and has as its object to provide a positioning device capable of avoiding or minimizing the influence of any trouble in an exhaust source and a method of coping with the abnormality when the trouble occurs. I do.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a positioning device according to a first aspect of the present invention includes:
An opening communicating with the process chamber exposed to the reduced pressure, and a housing having a guide surface;
A moving block provided so as to be movable in at least one direction, in a state facing the guide surface via a predetermined gap,
A differential exhaust seal provided between the housing and the moving block, for sealing between the process chamber and the outside of the process chamber at a higher pressure than the process chamber,
A valve that opens or closes a pipe that communicates the differential exhaust seal with the negative pressure source,
A driving device for driving the valve,
The drive device detects the abnormality of the negative pressure source, drives the valve before the fluid suction operation of the negative pressure source stops, and closes the pipe. And
[0007]
The second method of coping with an abnormality of the positioning device of the present invention is as follows.
An opening communicating with the process chamber exposed to the reduced pressure; a housing having a guide surface; and a housing provided to be movable in at least one direction in a state facing the guide surface with a predetermined gap therebetween. Abnormality of a positioning device that is provided between the movable block and the casing and the movable block, and has a differential exhaust seal that seals between the process chamber and the outside of the process chamber having a higher pressure than the process chamber. When dealing with
When an abnormality occurs in a negative pressure source that sucks fluid through a pipe connected to the differential exhaust seal, the pipe is closed before the fluid suction operation of the negative pressure source stops. .
[0008]
[Action]
A positioning device according to a first aspect of the present invention includes a housing including an opening communicating with a process chamber exposed to a reduced pressure, a guide surface, and a housing facing the guide surface via a predetermined gap. A moving block provided so as to be movable in at least one direction, a difference provided between the housing and the moving block, and sealing between the process chamber and the outside of the process chamber at a higher pressure than the process chamber. A dynamic exhaust seal, a valve that opens or closes a pipe that communicates the differential exhaust seal with the negative pressure source, and a driving device that drives the valve; and the driving device includes a driving device for the negative pressure source. By detecting the abnormality, the valve is driven before the fluid suction operation of the negative pressure source stops, and the pipe is closed, so when an abnormality occurs in the negative pressure source, The pressure in the process chamber is By delaying the time to rise, for example, the processing object in the process can take measures such as sealing, it is possible to suppress the damage that the processing object is subjected.
[0009]
Furthermore, a plurality of the differential exhaust seals are provided, and when the valve is provided for a pipe connected to the differential exhaust seal on the side close to the process chamber, while reducing costs, This is preferable because abnormality in the negative pressure source can be dealt with.
[0010]
In addition, before the fluid suction operation is stopped, the device has a detection device that detects an abnormality of the negative pressure source and outputs a signal, and the driving device drives the valve according to a signal from the detection device. preferable.
[0011]
According to a second aspect of the present invention, there is provided a method for coping with an abnormality of a positioning device, comprising: an opening communicating with a process chamber exposed to a reduced pressure; a housing having a guide surface; and a predetermined gap with respect to the guide surface. A moving block provided so as to be movable in at least one direction, and provided between the housing and the moving block, the process chamber and the outside of the process chamber having a higher pressure than the process chamber. In a method for coping with an abnormality of a positioning device having a differential exhaust seal that seals a gap, when an abnormality occurs in a negative pressure source that sucks fluid through a pipe connected to the differential exhaust seal, the negative pressure Since the pipe is closed before the fluid suction operation of the source is stopped, when an abnormality occurs in the negative pressure source, by delaying the time during which the pressure in the process chamber rises, for example, the processing target being processed is To seal What measures can take, it is possible to suppress the damage that the processing object is subjected.
[0012]
The differential exhaust seal used in this specification refers to, for example, exhausting a gas in a minute gap between two opposing surfaces so that, in a non-contact state, the atmosphere on both sides sandwiching the opposing surfaces (for example, atmospheric pressure and (High vacuum) to maintain a constant state. In the embodiment described below, a member having an exhaust surface is referred to as a differential exhaust seal.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in comparison with comparative examples with reference to the drawings. FIG. 1 is a schematic sectional view of a positioning device shown as a comparative example, and FIG. 2 is a schematic sectional view of a positioning device of the present embodiment.
[0014]
As shown in FIG. 2A, a positioning device 10 according to the present embodiment includes a housing 11 including a process chamber P and having a cylindrical opening 11a communicating the process chamber P with the outside thereof. It has a moving block, that is, a shaft 12, which is inserted through the opening 11a and is movable in the direction of the arrow. The shaft 12 is supported by a guide (not shown) while maintaining a small gap with respect to the inner peripheral surface of the opening 11a. The process chamber P is suctioned by a turbo molecular pump (not shown) and has a negative pressure close to vacuum.
[0015]
Further, three peripheral grooves (differential pressure chambers) 11b, 11c, and 11d are formed on the inner peripheral surface (guide surface) of the opening 11a of the housing 11. The differential pressure chambers 11b, 11c, and 11d are connected to external exhaust pumps P1, P2, and P3, which are negative pressure sources, by pipes 13, 14, and 15, respectively. Valves V1 and V2 are arranged in pipes 13 and 14 communicating with the differential pressure chambers 11b and 11c on the side closer to the process chamber P.
[0016]
The driving device 16 has a function of controlling the driving of the exhaust pumps P1 and P2 and controlling the valves V1 and V2 to open or close the pipes 13 and 14 individually. The detection device 17 has a function of monitoring the exhaust pumps P1 and P2, and transmits a signal to the drive device 16 when an abnormality is detected. In addition, the abnormality of the exhaust pump is determined by combining information such as temperature rise or decrease of the cooling water for cooling the exhaust pump, supply of the purge gas (N ₂ ), increase of the load on the rotor, and abnormal heat generation of the pump body. I can judge. Such information can be obtained in real time, for example, by increasing the load on the rotor by monitoring changes in the power supplied to the rotor, and abnormal heat can also be generated in real time by installing thermocouples, etc., at each part of the pump. Obtainable. Further, when gas leaks occur in the portions of the pipes 13 and 14 between the valves V1 and V2 and the exhaust pumps P1 and P2, the detection device 17 can also output a signal by detecting an abnormality.
[0017]
Note that the comparative example shown in FIG. 1A is different from the embodiment of FIG. 2A only in that the valves V1 and V2, the driving device 16, and the detecting device 17 are not provided. Since they are common, the same reference numerals are given and the description is omitted.
[0018]
The operation of the present embodiment will be described with further reference to the flowchart of FIG. When the driving force of a driving source (not shown) is transmitted to the shaft 12, the shaft 12 moves (or rotates) in the direction of the arrow shown in FIG. The workpiece can be moved (or rotated) to an arbitrary position to perform processing in a vacuum atmosphere in the process chamber. At this time, since the drive device 16 has opened the valves V1 and V2, the differential pressure chambers 11b, 11c and 11d are sucked by the exhaust pumps P1, P2 and P3 via the pipes 13, 14, and 15, respectively. Therefore, even if the outside of the housing 11 is at atmospheric pressure, the degree of vacuum in the process chamber P is maintained regardless of the movement of the shaft 12.
[0019]
By the way, in the comparative example shown in FIG. 1A, if an abnormality occurs in the exhaust pump P2 and the fluid suction capacity is finally lost, external air flows into the differential pressure chamber 11c via the exhaust pump P2. Therefore, the pressure in the differential pressure chamber 11c quickly approaches the atmospheric pressure. In such a case, even if the exhaust pump P3 operates normally, it does not contribute to maintaining the degree of vacuum in the process chamber P, and is in a state equivalent to the positioning device shown in FIG. 1B. In such a case, in order to maintain the degree of vacuum in the process chamber, it is necessary to rely only on the fluid suction stress of the exhaust pump P1, but in order to allow the exhaust pump P1 to have a margin for such an unexpected situation. It is necessary to use a very high performance exhaust pump. As described below, according to the present embodiment, such a problem can be avoided. Although FIG. 1 shows a case where the exhaust pump P2 stops due to an abnormality, a more serious problem occurs when the exhaust pump P1 stops due to an abnormality. That is, the state becomes substantially equivalent to a state in which there is no differential exhaust seal at all, and a vacuum in the process chamber P cannot be established.
[0020]
In the control according to the present embodiment shown in FIG. 3, in step S101, the detection device 17 continues to monitor the abnormality of the exhaust pumps P1 and P2. Here, for example, when an abnormality occurs in the exhaust pump P2 as shown in FIG. 2A, the abnormality coping method from step S102 is executed. More specifically, in step S101, when the detecting device 17 detects that an abnormality such as a temperature rise exceeding a threshold value has occurred in the exhaust pump P2, a signal indicating the abnormality is sent to the driving device 16 in step S102. Output. In step S103, the driving device 16 drives the valve V2 corresponding to the exhaust pump P2 in which the abnormality has occurred in response to the signal from the detection device 17, and closes the pipe 14.
[0021]
Further, in step S104, the driving device 16 waits until a predetermined time has elapsed since the valve was closed, and after the predetermined time has elapsed, stops the operation of the exhaust pump P2 in step S105.
[0022]
According to the present embodiment, the pipe 14 is closed by the valve V2 before the fluid suction capacity of the exhaust pump P2 is completely lost, so that even if the pipe 14 is opened to the atmosphere via the exhaust pump P2, the pipe 14 is closed. As a result, the outside air does not flow into the differential pressure chamber 11c, so that it is possible to suppress a sharp decrease in the sealing performance of the differential exhaust seal. This effect continues until the differential pressure chamber 11c and the space from the differential pressure chamber 11c to the valve V2 are filled with the gas that should be originally sucked by the exhaust pump P2, and the equilibrium state is reached. After the equilibrium state is reached, in this embodiment, the state becomes equivalent to that of the positioning device shown in FIG. 2B, that is, not only the exhaust pump P1 but also the exhaust pump P3 is effectively made to receive air from the outside. Is prevented from entering the process chamber P, and a decrease in the sealing performance is minimized. For example, the exhaust pump P2 may be repaired in this state, or the exhaust pump P2 may be repaired. During the time for repairing P2, measures such as sealing the work attached to the shaft 12 can be taken.
[0023]
As is apparent from FIG. 2, when an abnormality occurs in the exhaust pump P1, the pipe 13 may be closed by the valve V1. This prevents the vacuum break of the process chamber P from occurring as in the case of the comparative example in which an abnormality occurs in the exhaust pump P1. In the present embodiment, the valve is not provided in the pipe 15 on the side far from the process chamber P because the differential pressure chamber 11d connected to the pipe 15 is adjacent to the atmosphere, and therefore, even if an abnormality occurs in the exhaust pump P3. Even if the pipe 15 is closed, the pressure in the differential pressure chamber 11d immediately approaches the atmospheric pressure, so that the effect is not so high and is omitted in consideration of cost. Further, in the present embodiment, a three-stage differential exhaust seal (in which three differential pressure chambers are arranged) has been described, but the present invention can be similarly applied to a two-stage or four-stage or more differential exhaust seal. If the gap between the shaft 12 and the opening 11a is sufficiently small, there is an effect in delaying the rise in the pressure of the process chamber P, so that the present invention can be applied to a one-stage differential exhaust seal. As described above, in the present embodiment, a valve is not provided in the pipe 15 of the exhaust pump P3. However, the provision of the valve is somewhat more effective than the case where no valve is provided. Since the back diffusion of grease or the like can be prevented, it is more preferable to provide a valve also in the pipe 15 so that P3 abnormality detection and valve closing can be performed.
[0024]
FIG. 4 is a schematic cross-sectional view of the positioning device according to the second embodiment. In the present embodiment, the only difference is the shape of the housing and the moving block, and the point that the differential exhaust seal is provided in two stages.
[0025]
In FIG. 4, a housing 11 'having a process chamber P therein has no bottom wall, and is closed by a plate-shaped moving block 12' with a small gap. The moving block 12 'is supported by a guide (not shown), and is movable in the left-right direction and the direction perpendicular to the plane of the drawing.
[0026]
The side wall of the housing 11 'forms an opening, and its end surface serves as a guide surface 11a'. Two circumferential grooves (differential pressure chambers) 11c and 11d are formed on the guide surface 11a '. The differential pressure chambers 11c and 11d are connected to external exhaust pumps P2 and P3 as negative pressure sources by pipes 14 and 15, respectively. A valve V2 is disposed in the pipe 14 communicating with the differential pressure chamber 11c on the side closer to the process chamber P.
[0027]
The drive device 16 has a function of controlling the drive of the exhaust pump P2 and controlling the drive of the valve V2 to open or close the pipes 14 individually. The detection device 17 has a function of monitoring the exhaust pump P2, and transmits a signal to the drive device 16 when an abnormality is detected.
[0028]
Also in the present embodiment, when an abnormality occurs in the exhaust pump P2, the pipe 14 is closed by the valve V2 before the fluid suction capability of the exhaust pump P2 is completely lost. Even if it is opened to the outside, the outside air does not flow into the differential pressure chamber 11c from the pipe 14, so that a sharp decrease in the sealing performance of the differential exhaust seal can be suppressed.
[0029]
As described above, the present invention has been described with reference to the embodiments. However, the present invention should not be construed as being limited to the above embodiments, and it is needless to say that modifications and improvements can be made as appropriate. For example, an abnormality in the exhaust pump is detected by a detection device, and the driving device automatically closes a valve corresponding to the exhaust pump in which the abnormality has occurred. May be detected, and the corresponding valve may be closed before the exhaust pump loses the fluid suction stress.
[0030]
【The invention's effect】
A positioning device according to a first aspect of the present invention includes a housing including an opening communicating with a process chamber exposed to a reduced pressure, a guide surface, and a housing facing the guide surface via a predetermined gap. A moving block provided so as to be movable in at least one direction, a difference provided between the housing and the moving block, for sealing between the process chamber and the outside of the process chamber at a higher pressure than the process chamber. A dynamic exhaust seal, a valve that opens or closes a pipe that communicates the differential exhaust seal with the negative pressure source, and a driving device that drives the valve; and the driving device includes a driving device for the negative pressure source. By detecting the abnormality, the valve is driven before the fluid suction operation of the negative pressure source stops, and the pipe is closed, so when an abnormality occurs in the negative pressure source, The pressure in the process chamber is By delaying the time to rise, for example, the processing object in the process can take measures such as sealing, it is possible to suppress the damage that the processing object is subjected.
[0031]
According to a second aspect of the present invention, there is provided a method for coping with an abnormality of a positioning device, comprising: a housing provided with an opening communicating with a process chamber exposed to a reduced pressure; a housing provided with a guide surface; A moving block provided so as to be movable in at least one direction, in a state opposed to the processing chamber, provided between the housing and the moving block, and between the process chamber and the outside of the process chamber at a higher pressure than the process chamber. In a method for coping with an abnormality of a positioning device having a differential exhaust seal that seals a gap, when an abnormality occurs in a negative pressure source that sucks a fluid through a pipe connected to the differential exhaust seal, the negative pressure Since the pipe is closed before the fluid suction operation of the source is stopped, if an abnormality occurs in the negative pressure source, by delaying the time during which the pressure in the process chamber rises, for example, the processing target being processed is To seal What measures can take, it is possible to suppress the damage that the processing object is subjected.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a positioning device according to a comparative example.
FIG. 2 is a schematic configuration diagram of a positioning device according to the present embodiment.
FIG. 3 is a control flowchart according to the embodiment.
FIG. 4 is a schematic configuration diagram of a positioning device according to a second embodiment.
[Explanation of symbols]
11, 11 'Housing 12 Axis 12' Moving block 13, 14, 15 Piping 16 Drive 17 Detector V1, V2 Valve P1, P2, P3 Exhaust pump P Process chamber

Claims (4)

An opening communicating with the process chamber exposed to the reduced pressure, and a housing having a guide surface;
A moving block provided so as to be movable in at least one direction, in a state facing the guide surface via a predetermined gap,
A differential exhaust seal provided between the housing and the moving block, for sealing between the process chamber and the outside of the process chamber at a higher pressure than the process chamber,
A valve that opens or closes a pipe that communicates the differential exhaust seal with the negative pressure source,
A driving device for driving the valve,
The drive device detects the abnormality of the negative pressure source, drives the valve before the fluid suction operation of the negative pressure source stops, and closes the pipe. Positioning device. The said differential exhaust seal is provided with two or more, and the said valve is provided with respect to the piping connected to the said differential exhaust seal near the said process chamber, The Claim 1 characterized by the above-mentioned. Positioning device. Before the fluid suction operation is stopped, it has a detection device that detects an abnormality of the negative pressure source and outputs a signal, and in accordance with a signal from the detection device, the driving device drives the valve. The positioning device according to claim 1 or 2, wherein: An opening communicating with the process chamber exposed to the reduced pressure; a housing having a guide surface; and a housing provided to be movable in at least one direction in a state facing the guide surface with a predetermined gap therebetween. Abnormality of a positioning device that is provided between the movable block and the casing and the movable block, and has a differential exhaust seal that seals between the process chamber and the outside of the process chamber having a higher pressure than the process chamber. When dealing with
When an abnormality occurs in a negative pressure source that sucks fluid through a pipe connected to the differential exhaust seal, the pipe is closed before the fluid suction operation of the negative pressure source stops. How to deal with abnormalities of positioning device.

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