Patent Application
20050011351
1. Field of the Invention
The present invention relates to the controlling of pressure in a fluid system. More particularly, the present invention relates to a method of and apparatus for establishing and maintaining a predetermined level of pressure within at least one processing chamber that forms part of a closed atmosphere.
2. Description of the Related Art
In general, the manufacturing of high-tech products, including semiconductor devices, requires establishing precise conditions in a production environment to achieve high yields. These conditions include pressure, temperature, environmental purity and the like. In such a production environment, pressure is regarded as a key factor in preventing the influx of external contaminants as well as a parameter necessary for facilitating certain processes. An example of a production environment in which a certain level of pressure must be established and maintained will be described with reference to prior art semiconductor device manufacturing and processing facilities.
The facility 10 also includes a transfer chamber 14 positioned at one side of the loadlock chambers 12a, 12b. The transfer chamber is disposed in-line with the loadlock chambers 12a, 12b and is placed in selective communication therewith via doors D′. The inside of the transfer chamber 14 is generally kept at a predetermined negative pressure, which will hereinafter be referred to as vacuum pressure. In addition, a robot 16 is installed at a predetermined position within the transfer chamber 14. The robot 16 is configured to fixedly support individual wafers and is programmed to transfer the wafers to various positions within the facility 10.
Processing chambers 18a, 18b for processing the wafers and auxiliary chambers 20a, 20b, 20c, 20d for performing pre- and post-processing steps are installed at the other side of the transfer chamber 14. The processing chambers 18a, 18b and the auxiliary chambers 20a, 20b, 20c, 20d selectively communicate with the transfer chamber 14 via respective doors D′. Like the transfer chamber 14, the insides of the processing chambers 118a, 18b and auxiliary chambers 20a, 20b, 20c, 20d are all kept at a predetermined vacuum pressure.
In this type of facility, one purpose of the loadlock chambers 12a, 12b is to provide a transition for the wafers—from the room pressure state of the processing line to the vacuum pressure required for the processing of the wafers. Another purpose of the loadlock chambers 12a, 12b is to prevent particles from the production line from invading the downstream chambers when the wafers are introduced into the processing facility 10.
The time that it takes to change the pressure state in a loadlock chamber 12a, 12b, from room pressure to the required vacuum pressure state and vice versa, is proportional to the size of the loadlock chamber 12a, 12b. Therefore, any unnecessary space within the loadlock chambers 12a, 12b must be minimized in an effort to reduce the overall processing time.
Moreover, the pressure states within any of the chambers 12a, 12b, 14, 18a, 18b, 20a, 20b, 20c, 20d must be maintained when the doors D′ associated therewith are simultaneously open while the wafers W are being transferred therebetween. Otherwise, the gas within these chambers would flow out due to a pressure difference between the chambers. If the gas were to flow from one chamber to another, the gas might entrain particles, whereby the wafers W or the processing facility 10 could become contaminated. Also, the flow of gas might give rise to an eddy phenomenon which could, in turn, bring about a change in other processing conditions such as temperature, the supply of processing gas, pressure and the like. In these cases, the changes in the processing conditions could lead to processing failures.
Conventional pressure control apparatus 60 for balancing the pressure between first and second mutually communicating object chambers is shown in
Also, pressure supply systems 68a, 68b are coupled to other sides of the first and second object chambers 62a, 62b for supplying a predetermined level of pressure into the object chambers 62a, 62b according to the control signals transmitted from the controller 64. The pressure supply systems 68a, 68b comprise a vacuum pump 70 connected to the object chambers 62a, 62b by vacuum lines Va, Vb, respectively, a gas supply device 72 connected to the object chambers 62a, 62b by gas supply pipes Sa, Sb, respectively, and valves 74a, 74b, 74c, 74d disposed in the vacuum lines Va, Vb and the gas supply pipes Sa, Sb for selectively shutting down the flow of gas therethrough.
The pressure control system 60 attempts to establish an identical level of pressure between the first and second object chambers 62a, 62b as follows. First, the controller 64 respectively checks the internal pressures of the first and second chambers 62a, 62b with the pressure sensors 66a, 66b. If there is a difference in pressure between the first and second object chambers 62a, 62b, the valves 74a, 74b, 74c, 74d in the vacuum lines Va, Vb and gas supply lines Sa, Sb are selectively controlled and opened to supply vacuum pressure or purge gas, thereby adjusting the internal pressure levels of the first and second object chambers 62a, 62b. Then, when the pressure levels of the first and second object chambers 62a, 62b reach the required levels, the controller 64 the valves 74a, 74b, 74c, 74d in the vacuum lines Va, Vb or gas supply pipes Sa, Sb. At the same time, the controller 64 controls the operations of the vacuum pump 70 and the gas supply device 72.
The pressure within the first and second object chambers 62a, 62b is controlled by supplying vacuum pressure or purge gas based on signals generated by the pressure sensors 66a, 66b until the desired internal pressures of the first and second object chambers 62a, 62b are established. However, the detected levels of pressure are not always accurate while the pressure levels are being adjusted, and it is difficult to effect the delicate feedback control required in providing vacuum pressure or purge gas while the pressure levels are being adjusted.
Furthermore, if the internal pressure level of the object chambers becomes exceeds the desired vacuum pressure or positive pressure, additional purge gas or vacuum pressure must be supplied to the respective object chambers, thereby delaying the processing of the wafers. Accordingly, it is important to form a very precise internal pressure within the object chambers from the start. Therefore, the pressure sensors 66a, 66b must be able to detect the static pressure level of the object chambers.
A boat 38 containing a plurality of wafers W is raised from the loadlock chamber 32 to introduce the wafers W into the processing chamber 34. At this time, a block plate 36 seals off the atmosphere of the upper processing chamber 34 from that within the loadlock chamber 32. Then, the wafers W are processed by processing gas at a predetermined vacuum pressure atmosphere and at a certain temperature.
When the processing of the wafers W is completed, the boat 38 loaded with the wafers W is lowered back down into the loadlock chamber 32 while the block plate 36 allows the atmospheres within the processing chamber 34 and the loadlock chamber 32 to communicate.
In this type of facility 30, the atmospheres within the processing chamber 34 and the loadlock chamber 32 become different in terms of pressure and temperature, thereby leading to a natural flow of gases when the block plate 36 opens the processing chamber 34. Even when a balanced pressure state is formed between the processing chamber 34 and the loadlock chamber 32 before the processing chamber 34 is opened by the block plate 36, the relative size of the effective spaces within the processing chamber 34 and the loadlock chamber 32 continuously change by as much as the volume of the block plate 36 and the boat 38. As a result, a pressure differential is produced, thereby causing gas to flow between the loadlock chamber 32 and the processing chamber 34. In this case, particles within the loadlock chamber 32 are introduced into the processing chamber 34, resulting in the contamination of the wafers W and the processing chamber 32.
Also, the various gases induced into the processing chamber 34 are at a relatively low temperature. Accordingly, the wafers W at the bottom of the boat 38 cool more rapidly than those at the top of the boat 38. This condition produces differences in the processed states of the wafers W and leads to a sudden crystallization of the gas remaining within the processing chamber 34. As a result, particles are created and the processed wafers W are not uniform.
Therefore, in order to solve the aforementioned problems, efforts should be made to achieve a pressure balance between the processing chamber 34 and the loadlock chamber 32 and to minimize a change in pressure and temperature caused by the volumetric fluctuations due to the movement of the block plate 36 and the boat 38.
Conventional pressure control apparatus aimed at solving the problems of the prior art in the manner described above is shown in
The pressure supply system 48 is installed at one side of the object chamber 42 for creating a predetermined level of pressure within the object chamber 42 according to a control signal input thereto from the controller 44. The pressure supply system 48 includes a gas supply device 52 connected to the object chamber 42 by a gas supply pipe S, a vacuum pump 50 connected to the object chamber 42 by a vacuum line V, and valves 54a, 54b for selectively stopping the flow of gases through the gas supply pipe S and vacuum line V.
Next, the steps of establishing a predetermined vacuum pressure within the object chamber 42 will be described. First, the controller 44 drives the vacuum pump 50 with the valve 54b open to create a predetermined vacuum pressure within the object chamber 42. In the course of the operation, the controller 44 continuously monitors the internal pressure of the object chamber 42 with the pressure sensor 46. When the internal pressure of the object chamber 42 approaches the desired level, the controller 44 controls the degree of opening of the valve 54b on the vacuum line V. Then, when the internal pressure state of the object chamber 42 reaches the required level of pressure, the controller 44 closes the valve 54b and at the same time shuts down the operation of the vacuum pump 50.
On the other hand, a room pressure atmosphere is established within the object chamber 42 as follows. The controller 44 opens the valve 54a of the gas supply pipe S and drives the gas supply part 52 to supply a predetermined purge gas into the object chamber 42. The internal pressure of the object chamber 42 is detected by the pressure sensor 46 and a signal indicative of the pressure is transmitted to the controller 44. The controller 44 controls the valve 54a and the gas supply part 52 until the internal pressure of the object chamber 42 reaches room pressure.
However, it is difficult to accurately establish a desired level of pressure by controlling the degree of opening of the valves 54a, 54b and the operations of the vacuum pump 50 and gas supply part 52. In particular, the pressure in the object chamber 42 becomes unstable while fluid is flowing thereinto/therefrom in the course of providing the chamber 42 with vacuum pressure or purge gas. Accordingly, the pressure detected by the pressure sensor 46 is unreliable, and it is difficult to precisely control the supply of vacuum pressure or purge gas.
Moreover, the pressure in the object chamber 42 has a direct effect on the processing that occurs in the chamber. Therefore, an important aspect of the processing operation is to form an extremely precise pressure state in the object chamber 42. If the internal pressure level of the object chamber 42 becomes higher than the desired vacuum pressure or a predetermined high pressure, purge gas or vacuum pressure must be provided immediately. Thus, the pressure sensor 46 must detect the static pressure state of the object chamber 42, so that it is possible to keep the pressure level of the object chamber 42 precise, that is, neither lower nor higher than the required pressure level.
An object of the present invention is to solve the aforementioned problems of the prior art. It is therefore one object of the present invention to provide a pressure control system and method that can rapidly establish a desired level in at least one chamber in a processing facility. It is another object of the present invention to provide a pressure control system and method that can precisely achieve a balance in pressure between chambers that are to be placed in open communication to facilitate the transfer of objects, such as wafers, therebetween. It is still another object of the present invention to provide a pressure control system and method that can prevent a processing facility having one or more processing chambers from being contaminated by foreign particles.
According to one of the present invention, a pressure control system for controlling the internal pressure of the chamber, comprises: a pressure sensor connected to the chamber, a controller operatively connected to the pressure sensor so as to receive signals indicative of the internal pressure of the chamber from the pressure sensor, at least one space increase/decrease device comprising a movable partition exposed to and delimiting the interior of the chamber, and a driving system operatively connected to the partition and to the controller so as to control the relative position of the partition according to a control signal issued by the controller. The partition is supported so as to be movable relative to fixed sidewalls of the chamber. Accordingly, the movement of the partition can selectively increase and decrease the volume of free space within the chamber. In addition, a pressure supply system is connected to the chamber so as to create a state of pressure within the chamber.
The partition may be a piston slidably fitted within a pipe as sealingly engaged therewith. The driving system may include a pressure-actuated cylinder to control the sliding of the piston within the pipe.
Alternatively, the partition may be a flexible tube corrugated along the length thereof such that the flexible tube is expandable and contractable. In this case, the chamber has a through-hole extending through a sidewall portion thereof. The flexible tube has a closed end, and an open end fixed relative to the sidewall portion so as to provide an air-tight enclosure for the through-hole. The driving system is operative to move the closed end of the flexible tube.
In addition, the pressure supply system may also comprise a case disposed over and covering the space increase/decrease device at the exterior of said chamber, and a secondary pressure sensor disposed at one side of said case so as to detect the pressure within the case. The pressure supply system is connected to the case. The pressure within the case is thus adjustable by the pressure supply system to reduce a difference in pressure between the inside of the chamber and the inside of the case. Accordingly, the load on the partition can be minimized.
A desired level of pressure is established within chamber as follows. The pressure supply system provides the chamber with positive or negative pressure while the pressure is monitored by the pressure sensor and the controller. The controller determines whether the pressure within the chamber equals a predetermined level of pressure. As soon as the pressure within the chamber equals the predetermined pressure, the operation of the pressure supply system is operated to cut off, whereby the pressure in the chamber becomes static. Finally, once the pressure in the chamber has become static, the effective volume of free space in the chamber is varied by the space increase/decrease device to change the pressure in the chamber from the predetermined pressure to the desired pressure.
Preferably, the partition is moved in a direction that reduces the volume of free space within the chamber while the pressure in the chamber is being increased or decreased during the course of producing the predetermined level of pressure. In this way, the amount of time necessary to produce the predetermined level of pressure in the chamber is decreased.
According to another aspect of the present invention, a pressure control system for controlling the internal pressures of at least two interconnected chambers, comprises at least one space increase/decrease device each defining a passageway that extends between the chambers, and having a partition disposed in the passageway. The partition is exposed to and delimits the interiors of both of the chambers. The partition is also supported so as to be movable relative to fixed sidewalls of the chambers, whereby the partition can be moved to selectively increase the volume of free space within one of the chambers and decrease the volume of free space within the other of the chambers. Hence, the pressure levels in the chambers can be balanced.
Preferably, the pressure control system includes two space increase/decrease devices. The passageway of one of the devices extends through a common sidewall that separates the interior of the chambers from one another. On the other hand, the passageway of the other space increase/decrease device extends outside of the chambers between respective fixed sidewalls thereof.
The partition may be a piston slidable along the passageway as sealing engaged therewith. Preferably, the piston comprises a pair of piston members spaced from one another along the length of the passageway, and a support member interconnecting and spacing the piston members apart. In this case, a driving system operatively connected to the controller may be connected to the space increase/decrease device between the piston members thereof to control the movement of the piston members. Still further, a brake may be interposed between the piston members and operative to selectively fix the piston members in place in the passageway.
On the other hand, the partition may be one or more flexible tubes corrugated along the length thereof whereby the flexible tube is expandable and contractable. The flexible tube has a closed end, and an open end fixed relative to the sidewalls of the chambers.
The pressure control system may also comprise a secondary pressure sensor disposed in the passageway of each space increase/decrease device, and a pressure supply system connected to the chambers and to the passageway. The pressure supply system is operatively connected to the controller so as to create a state of pressure within the chambers and the passageway under the control of said controller based on the levels of pressure as detected by the respective pressure sensors.
The pressure in the chambers can be balanced as follows before the chambers are placed in open communication with one another. First, the pressure within the chambers is monitored by the pressure sensors and controller. The pressure supply system is controlled to provide only a selected one of the chambers with positive or negative pressure to increase or decrease the pressure within that chamber. The controller then determines whether the pressure within the selected chamber equals a predetermined level. As soon as the pressure within the chamber equals the predetermined pressure, the pressure supply system is operated to stop providing the chamber with positive or negative pressure. Under these conditions the space increase/decrease device can be used to balance the levels of pressure within the chambers by increasing the volume of the free space in one of the chambers while decreasing the volume of free space in the other of the chambers.
More specifically, the movement of the partition(s) of the space increase/decrease device(s) maybe sufficient to effect the total changes in volumes necessary to achieve the balance of pressure in the chambers. However, if need be, if the volumetric capacity of the pressure increase decrease device(s) is insufficient, the pressure supply system can be operated to supply purge gas into one of the chambers until the pressure levels are precisely balanced.
The brake of the space increase/decrease device can be controlled to fix its associated partition in place while the selected chamber is provided with positive or negative pressure, to then release the partition once the positive or negative pressure is no longer being provided, and to again fix the partition in place once the levels of pressure within the chambers have become equal.
These and other objects, features and aspects of the invention will become apparent from the following description of the preferred embodiments thereof made with reference to the accompanying drawings, of which:
Hereinafter, preferred embodiments of a pressure control apparatus and a pressure control method in accordance with the present invention will be described in detail with reference to accompanying drawings. Like reference numerals designate like parts throughout the drawings.
Referring first to
The pressure supply system 88 includes a vacuum line V connected to the chamber 82, a vacuum pump 90 that exhausts the chamber 82 through the vacuum line V, a gas supply pipe S connected to the chamber 82, a gas supply part 92 that supplies purge gas into the chamber 82 through the gas supply pipe S, and valves 94a, 94b disposed in the vacuum and gas lines V, S to selectively shut down the flow of fluid therethrough according to a control signal input from controllers 84a, 84b.
The pressure control apparatus 80 also includes at least one space increase/decrease device 96a, 96b connected to the chamber 82. The space increase/decrease device 96a, 96b comprises a partition that delimits the chamber 82. The position of the partition can be changed to, in effect, reduce or expand the volume of the chamber 82. To this end, the space increase/decrease device 96a, 96b is connected to a driving system 98a, 98b for varying the position of the partition relative to the fixed sidewalls that delimit the interior of the chamber 82.
A first embodiment of the space increase/decrease device, namely space increase/decrease device 96a will be described with reference to
Referring again to
Alternatively, the driving system 98a may include a motor to be controlled by the controller 84a, screw threads formed on the motor axle or on an output shaft connected with the motor axle, and a slider connected to the piston 102 and threaded to the motor axle or the output shaft so as to slide the piston 102 when the motor axle or the output shaft is rotated. In this case, the slider may be integral with the piston 102. Still further, the driving system 98a may instead comprise a rack and pinion, or a cam mechanism for converting rotation of the cam into straight line reciprocating movement of the piston 102.
In addition, a flexible tube 108 extends between the pipe 100 and the piston 102 for ensuring the air-tightness of the chamber 82 at the piston 102 and pipe 100. The flexible tube 108 may be a corrugated metal flex tube (shape of a bellows) or a rubber tube.
Also, a case 110 can be used instead of or in addition to the tube 108 to provide an air-tight cover for the space increase/decrease part 96a. Another pressure sensor 86a may be installed at one side of the case 110 for detecting the internal pressure of the case 110 and transmitting a signal indicative of the detected pressure to the controller 84a.
Furthermore, a pressure supplying system 88a can be connected to the space increase/decrease device 96a. The pressure supplying system 88a supplies pressure according to signals from the controller 84a when there is a difference in pressure between the chamber 82 and the inside of the case 110 to reduce the load of driving the piston 102. The pressure supplying system 88a can be an integral part of the main pressure supplying system 88 or can be a totally independent system. If the pressure supplying system 88a is an integral part of the main pressure supplying system 88, the vacuum line V and gas supply pipe S of the main pressure supplying system 88 are merely integrated with the case 110. This can be accomplished by a three-way valve 111 to selectively control the supply of vacuum pressure or purge gas according to the control signals issued by the controller 84a.
The method of controlling the pressure in the chamber 82 of the system 80 will be described with reference to
In this method according to the present invention, the level of pressure at which the valves 94a, 94b are shut, that is, the preset pressure, may be less than the level of pressure that is desired in the chamber 82. In this case, the space increase/decrease device 96a is used to reduce the internal volume of the chamber 82. In other words, the piston 102 is moved inwardly relative to the chamber 82. On the other hand, the preset level of pressure when the valves 94a, 94b are shut may be greater than a desired vacuum pressure. Accordingly, the space increase/decrease device 96a is used to expand the internal volume of the chamber 82. In other words, the piston 102 is moved outwardly relative to the chamber 82. In view of the above, the stroke of the piston 102 must be great enough to sufficiently increase or decrease the internal volume of the chamber 82. Preferably, then, the piston 102 is set up in the middle of the tube 100 so that it may either expand or reduce the internal volume of the chamber 82.
In the above-described process, the vacuum pressure is supplied while the piston 102 reduces the internal volume of the chamber 82, thereby in effect reducing the time during which the vacuum pressure must be provided to create the preset level of pressure in the chamber 82. Then, the internal volume of the chamber 82 is increased or decreased by the piston 102 in response to the pressure detected by the pressure sensor 86, that is the static level of pressure that is present without fluid flowing through the chamber. That is, the chamber 82 is rapidly provided with vacuum pressure through the vacuum line V without the need to control the valves 94a, 94b, thereby also saving time in achieving the desired vacuum pressure in the chamber 82.
The space increase/decrease device may also have a structure as shown in any of
First, referring to
In addition, a driving system 98b is operatively connected to the flex tube 114 to change the shape of the tube 114 by varying the position of the closed end of the tube 114 according to a control signal issued by the controller 84b. As with the driving system 98a described above in connection with the space increase/decrease device 96a, the flex tube 114 can be expanded or contracted by a rod 116 connected to the closed end of the tube 114 and which rod 116 is driven by means such as a cylinder, motor or cam mounted to the external part of the chamber 82. If desired, the pressure control system may include a space increase/decrease device 96a and a driving system 98a disposed across the chamber 82 from the increase/decrease device 96b and driving system 98b that all together are controlled by controllers 84a, 84b to form a desired level of pressure in the chamber 82.
In addition, a case 110b may be mounted to the outside of the chamber 82 for covering the space increase/decrease device 96b, that is, the location where the flex tube 114 is attached to the chamber 82, to maintain the air-tightness of the structure. Another pressure sensor 86b is mounted to one side of the case 110b for detecting the internal pressure of the case 110b and to transmit a signal indicative of the detected pressure to the controller 84b. A pressure supply system 88b is connected to the other side of the case 110b for creating a predetermined level of pressure in the case 110b, under the control of the controller 84b, to reduce the load on the tube 114 by reducing any difference in pressure between the inside of the chamber 82 and the inside of the case 110b. The pressure supply system 88b may be configured similar to that of the pressure supply system 88a described in connection with the case 110a and piston 102.
Furthermore, the pressure supply system 88b can be used as means for controlling the expansion and contraction of the flex tube 114. In this case, the driving system 98b can serve as a stopper for limiting the extent to which the tube 114 can be expanded and contracted.
In the embodiment of
In the embodiment shown in
The method of forming the desired level of pressure within the chamber 82 using these space increase/decrease devices 96b and driving systems 98b is similar to the method described above in connection with the space increase/decrease devices 96a. Therefore, a detailed description of the method will be omitted for the sake of brevity.
Next, preferred embodiments of pressure control apparatus 120 for establishing a desired balanced pressure in two or more partitioned chambers 122a, 122b will be described with reference to
The pressure control apparatus 120 includes a controller 128, and pressure sensors 130a, 130b disposed at predetermined parts of the chambers 122a, 122b for detecting the internal pressure of the respective chambers 122a, 122b and transmitting signals indicative of the detected pressures to the controller 128. Also, a pressure supply system 132 is connected in common to other parts of the chambers 122a, 122b and is operated according to a control signal transmitted from the controller 128 to provide a predetermined level of pressure in the chambers 122a, 122b.
Space increase/decrease devices 126a, 126b are disposed in and/or define the passages 124a, 124b. The space increase/decrease device 126a (
The first embodiment of the space increase/decrease device, namely space increase/decrease device 126a, will be described in more detail with reference to
Also, the piston 134 may comprise two or more separate piston members 134a, 134b. In this case, a support member 138 such as a tie rod may connect the piston members 134a, 134b together so as to maintain their spacing and cause them to slide in unison.
In addition, the pressure control apparatus 120 includes driving systems 140a, 140b for controlling the movement of the respective partitions of the space increase/decrease devices 126a, 126b according a control signal from the controller 128, to in effect establish the internal volumes of the chambers 122a, 122b. The control signal, i.e., the control of the driving systems 140a, 140b, is based on the signals indicating the internal pressure levels of the chambers 122a, 122b transmitted from the pressure sensors 130a, 130b.
The driving systems 140a, 140b may comprise brakes interposed between the piston members 134a, 134b. The brakes are operable to fix the piston members 134a, 134b in selected positions within the passageways 124a, 124b. Each brake may be in the form of a brake cylinder(s) fixed to the center of the support member 138 and operable press against the lateral wall defining the respective connection passage 124a, 124b when directed to by the controller 128 to fix the piston members 134a, 134b in place. Alternatively, the brake cylinder(s) may be fixed to the lateral wall defining the connection passage 124a, 124b and operable to press against and hence, brake, the support member 138. Such brakes are represented schematically in
The second embodiment of the space increase/decrease part device, namely, the space increase/decrease device 126b, will now be described with reference to
In the embodiment in which a space increase decrease device 126b has two flex tubes 142a, 142b, if one of the tubes is forced to contract or expand under pressure from the chamber 122a, 122b towards which it faces, the other flex tube will be corresponding expanded or contracted. The amounts of expansion or contraction of the flex tubes 142a, 142b result in a change in the internal volume of the chambers 122a, 122b and an equalization of the pressure levels thereof. Similar results occur even in the case of the space increase/decrease device 126a comprising piston members 134a, 134b, and in the cases of space increase/decrease devices 126a, 126b having only one piston member or flex tube.
The pressure control apparatus having space increase/decrease devices 126b comprising at least one corrugated flex tube 142, as such, may also comprise driving systems 140b for controlling the contraction or expansion of the tube(s) 142 under the direction of the controller 128. Each driving system 140b may be in the form of a brake or a cylinder.
The pressure control apparatus 120 may also include pressure sensors 130c (see
A method of forming equal pressures within the chambers 122a, 122b will now be described with reference to
First, the controller 128 checks the internal pressure states of the chambers 122a, 122b as detected by the pressure sensors 130a, 130b (ST202). Then, the controller 128 controls the pressure supply system 132 to change the pressure level within a selected one of the chambers 122a, 122b (ST204). During this time, the controller 128 keeps checking the pressure within the selected one of the chambers 122a, 122b and compares the pressure to a predetermined pressure (ST206).
The controller 128 shuts down the pressure supply system 132 when the internal pressure of the selected chamber 122a, 122b reaches the predetermined pressure level (ST208). At this time, the space increase/decrease part(s) 126a, 126b is/are in a free state (ST210), i.e., the partition(s) thereof are essentially free to move within the passageway(s) 124a, 124b. Therefore, any difference in the internal pressure of the chambers 122a, 122b moves the partition(s) in a direction that reduces the internal volume of the chamber 122a, 122b whose pressure level is lower than the other. On the other hand, the internal volume of the other chamber 122a, 122b is increased. As a result, the internal pressure levels of the chambers 122a, 122b become equal.
When the pressure control apparatus has driving systems 140a, 140b operatively connected to the space increase/decrease devices 126a, 126b, the controller 128 produces the predetermined pressure level in the selected chamber 122a, 122b while controlling the driving system 140a, 140b to prevent the partitions of the space increase/decrease devices 126a, 126b from moving. Once the predetermined pressure level is achieved, the controller 128 controls the driving systems 140a, 140b to release the space increase/decrease devices 126a, 126b, whereupon the pressure levels in the chambers 122a, 122b are balanced. Then, the driving systems 140a, 140b are controlled to once again fix the partitions of the space increase/decrease devices 126a, 126b in place. Then the door that places that chambers 126a, 126b in communication is opened.
In addition, the controller 128 may control the driving systems 140a, 140b to forcibly drive the partitions (pistons or flex tubes) of the space increase/decrease part(s) 126a, 126b in response to a change in pressure caused by a shift in the respective volumes of free space within the two chambers 122a, 122b while the chambers 122a, 122b are in open communication with another.
Typically, the preset pressure level of the selected chamber 122a, 122b is kept within a range that allows the space increase/decrease devices 126a, 126b to effect the changes in volumes necessary to achieve a balance in pressure. However, if the difference in pressure between the chambers 122a, 122b is greater than that which can be balanced by changing the volume of the chambers 122a, 122b using the space increase/decrease devices 126a, 126b, the pressure supply system 132 is operated to compensate. That is, the pressure supply system 132 is controlled by the controller 128 to make the internal pressure level of the selected chamber 122a, 122b equal to that of the other chamber 122a, 122b. At this time, the shifting of the space increase/decrease devices 126a, 126b is checked. Once the devices arrive at a position halfway between their maximum strokes, e.g., once the flex tubes 142a, 142b are located mid-way between the maximum states of extension and retraction thereof, the controller 128 instantly stops the supplying of positive or negative pressure through the pressure supply system 132. In the case of the connection passage 124b defined outside of the chambers 122a, 122b, the structure defining the connection passage 124b can be transparent so that the position of the piston 134 or the shape of the flex tube 142 can be visually conformed. Also, an electronic position detecting sensor (not shown) can be provided inside the passages to electronically sense the position of the piston 134 or the shape of the flex tube 142.
As is clear form the description above, the space increase/decrease devices 126a, 126b operate to keep the pressure of the two chambers 122a, 122b balanced. However, the space increase/decrease devices 126a, 126b may at times be fixed in place by the driving systems 140a, 140b, whereby the effective volumes of the two chambers 122a, 122b do not change. Also, once a body disposed in one chamber 122a, 122b is moved to the other chamber 122a, 122b, the space increase/decrease device 126a, 126b can operate passively or can be forced to, in effect, increase the volume of the chamber 122a, 122b from which the body has been withdrawn.
Accordingly, the internal pressure levels of the chambers can be balanced quickly, easily and precisely. Such a precise balance in pressure between the communicating chambers prevents the flow of fluids therebetween, thereby ensuring that the processing facility and the wafers are not contaminated. This, in turn, enhances the operational efficiency of processing facility and hence, the yield of products processed in the facility.
Although the present invention has been described above in connection with the preferred embodiments thereof, it is to be understood that the invention is not limited to those embodiments. Rather, various changes and modifications may be made to the preferred embodiments by one skilled in the art without departing from the true spirit and scope of the invention as defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2002-2715 | Jan 2002 | KR | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10322557 | Dec 2002 | US |
| Child | 10919252 | Aug 2004 | US |
