JP2009032933A - Flow evaluation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To evaluate a down flow of air in an exposure device. <P>SOLUTION: A flow evaluating device includes a body 36 to be tested which simulates a wafer stage 3, a container 30 which has a water feed port 31 facing the body 36 to be tested and a water drain port 32 provided on the opposite side from the water feed port 31 with the body 36 to be tested interposed therebetween and can have its inside observed, support means 37 and 39 of supporting the body 36 to be tested in the container, a flow generating means 25 of circulating liquid in the container through the wafer feed portion 31 and water drain port 32 to generate a flow equivalent to a down flow space, and a visualizing means of visualizing the flow of the liquid in the container. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a flow evaluation apparatus for evaluating a flow of downflow in a clean room or an exposure apparatus.

  As a countermeasure against chemical contamination in a semiconductor manufacturing process, an exposure apparatus that employs an air conditioning system called downflow is known (see, for example, Patent Document 1). Downflow is an air conditioning system that blows out air from the top of the apparatus and exhausts it from the bottom of the apparatus, thereby keeping the space around the wafer mounted on the wafer stage in the exposure apparatus in a highly clean state. Can do.

JP 2004-63934 A

  In this type of exposure apparatus, since the wafer and the wafer stage exist directly under the downflow, the downflow flow is disturbed. Therefore, for example, when the position of the wafer stage is measured using an interferometer, the position measurement accuracy of the wafer stage may be impaired due to the influence of the downflow flow such as air fluctuation in the interferometer optical path. In order to prevent this, it is preferable to evaluate the air flow around the wafer stage in advance, but it is difficult to evaluate the downflow air flow in the exposure apparatus.

The present invention is a flow evaluation device for evaluating the flow around an object installed in a downflow space where air flows from above to below, a specimen simulating the object, a water supply opening facing the specimen, And a drainage port provided on the opposite side of the water supply port with the specimen interposed therebetween, a container capable of observing the inside, a support means for supporting the specimen in the container, and the water supply port and the drainage port It is characterized by comprising a flow generating means for circulating a liquid in the container and generating a flow equivalent to the downflow space in the container, and a visualizing means for visualizing the flow of the liquid in the container.
The water supply port and the drain port are preferably provided at substantially the same height.
In this case, a rectifier that rectifies the flow of the liquid can be provided between the specimen and the drain.
A drainage port may be provided above the water supply port.
A support plate that simulates the floor or base below the object in the downflow space is placed between the specimen in the container and the drain, and the specimen is supported so as to be movable along the surface of the support plate. You can also.

  According to the present invention, it is possible to evaluate the state of downflow airflow in a clean room, an exposure apparatus, or the like.

-First embodiment-
A first embodiment of a flow evaluation apparatus according to the present invention will be described with reference to FIGS.
Below, the case where the downflow flow in an exposure apparatus is evaluated is demonstrated. FIG. 1 is a diagram showing a schematic configuration of a semiconductor exposure apparatus. The exposure apparatus 100 irradiates exposure light to illuminate the reticle R, a reticle stage 2 on which the reticle R is mounted, a wafer stage 3 on which the wafer W is mounted, and a pattern formed on the reticle R on the wafer W. And a projection optical system 4 for performing projection exposure. These components are accommodated in an exposure chamber 6 covered with a case 5. The exposure apparatus 100 is installed in a clean room.

  The reticle stage 2 is supported on the support base 7 so as to be movable in directions perpendicular to each other (hereinafter referred to as XY directions). The wafer stage 3 is supported on the base 8 so as to be movable in the XY directions. Each of the stages 2 and 3 is driven in the XY directions by a driving device such as a linear motor, for example.

  The position of reticle stage 2 in the XY direction and the position of wafer stage 3 in the XY direction are optically measured by interferometers 9a and 10a (for example, laser interferometers). The interferometers 9a and 10a irradiate measurement light toward the movable mirrors 9b and 10b fixed on the respective stages 2 and 3, and interference between reflected light from the movable mirrors 9b and 10b and reflected light from the reference surface. Thus, the positions of the reticle stage 2 and the wafer stage 3 are respectively measured. The stages 2 and 3 are driven based on the measurement result of the stage position, and the pattern formed on the reticle R is accurately projected and exposed at a predetermined position on the wafer W. The interferometers 9a and 10a and the movable mirrors 9b and 10b are provided for the X axis and the Y axis, respectively, but only one of them is shown here.

  A support frame 11 is horizontally mounted above the wafer stage 3, and a duct 12 is provided in the support frame 11. Air having a predetermined temperature generated by an air conditioner (not shown) is guided to the duct 12 and blown downward from a plurality of outlets 12 a formed on the lower surface of the duct 12. This conditioned air is exhausted out of the exposure chamber 6 through an exhaust port 12 b formed around the base 8. As a result, a downflow air flow is generated around the wafer W and the wafer stage 3, and the inside of the exposure apparatus can be kept clean. That is, the periphery of the wafer stage 3 can be a downflow space.

  In the present embodiment, a downflow flow in the exposure apparatus is simulated by the following flow evaluation apparatus. Fig.2 (a) is a front view which shows the whole structure of the flow evaluation apparatus based on 1st Embodiment, FIG.2 (b) is an arrow b figure of Fig.2 (a). The flow evaluation apparatus 200 includes a duct 20 through which water circulates and a water tank 30 provided in the middle of the duct 20 and is configured as a circulating water tank. The duct 20 has a pair of upper and lower horizontal duct portions 21 and 22 extending in the horizontal direction, and a pair of vertical duct portions 23 and 24 erected at both ends of the horizontal duct portions 21 and 22. The parts 21 and 22 and the vertical duct parts 23 and 24 communicate with each other.

  An impeller 25 is disposed in the horizontal duct portion 22, and a substantially rectangular parallelepiped water tank 30 is disposed in the horizontal duct portion 23. A water supply port 31 and a drain port 32 are opened at the same height on both side surfaces of the water tank 30, and the inside of the water tank communicates with the horizontal duct portion 22 through the water supply port 31 and the drain port 32. When the impeller 25 is driven, water flows into the water tank through the water supply port 31, passes through the water tank, and flows out from the drain port 32. The rotation speed of the impeller 25 can be changed. By adjusting the rotation speed of the impeller 25, the flow velocity of the water flowing in the water tank can be adjusted. The water tank 30 is entirely formed of a transparent plate 33 such as glass or acrylic so that the state inside the water tank can be visually observed from the outside.

  A rectifier 34 is attached to the inner wall of the water tank 30 so as to face the drain port 32, and a pseudo floor 35 is fixed in the water tank via the rectifier 34. A specimen 36 is provided on the surface of the simulated floor 35 so as to face the water supply port 31 and at almost the same height as the water supply port 31. The specimen 36 is slidably supported on the surface of the simulated floor 35 via struts 37. The upper end portion of the strut 37 penetrates the upper surface of the water tank 30 and is connected to an actuator 39 provided on a support base 38 above the water tank. The specimen 36 can be moved along the surface of the pseudo floor 35 in each direction (up / down / left / right and diagonal directions) indicated by arrows in FIG.

  3A is a perspective view of the rectifier 34 as viewed from the drain port 32 side, and FIG. 3B is a perspective view of the rectifier 34 as viewed from the water supply port 31 side. The rectifying device 34 includes a cross plate 341 formed so as to intersect substantially in an X shape, and a base plate 342 fixed to one end surface of the cross plate 341, and the pseudo floor 35 is fixed to the other end surface of the cross plate 341. Has been. A drain port 32 is opened at the center of the base plate 342. As shown in FIG. 3B, both the base plate 342 and the pseudo floor 35 are substantially rectangular, but the vertical and horizontal lengths of the pseudo floor 35 are shorter than the vertical and horizontal lengths of the base plate 342. A running water recovery unit 343 is provided around the pseudo floor 35.

  FIG. 4 is a diagram showing the flow of water in the water tank. The water that has flowed into the water tank 30 flows substantially vertically toward the surface of the simulated floor 35 as indicated by the arrows in the figure, and then passes through the flowing water recovery unit 343 outside the simulated floor 35 to the back side of the simulated floor 35. It detours and flows out of the central drain port 32. As a result, the flow in the vicinity of the drainage port is rectified, it is possible to prevent the occurrence of uneven flow due to the suction of the drainage port 32, and the periphery of the specimen 36 can be made uniform.

  Using the flow evaluation apparatus 200 described above, a downflow flow equivalent to that in the exposure apparatus is reproduced. Here, the water tank 30 simulates the exposure apparatus 100. For example, the specimen 36 corresponds to the wafer stage 3, and the pseudo floor 35 corresponds to the base 8. Further, the water supply port 31 corresponds to the air outlet 12a, and the running water recovery unit 343 and the drain port 32 correspond to the exhaust port 12b.

  Comparing the flow conditions in the exposure apparatus 100 and the water tank, the temperature-controlled air flows in the exposure apparatus, but the water flows in the water tank. For this reason, in order to evaluate as the same flow field, it is necessary to make both Reynolds number (Re number) correspond. When the representative speed is U, the representative length is d, and the kinematic viscosity coefficient is ν, the Re number is represented by Re = Ud / ν. For example, the kinematic viscosity coefficient ν of water at 20 ° C. is the kinematic viscosity coefficient ν of air. It will be about 1/15 of that. Accordingly, the representative length d of the specimen 36 and the pseudo floor 35 for matching the Re number can be shortened, and the water tank 30 can be downsized. The flow rate of water in the water tank, that is, the representative speed U can be adjusted by changing the rotation speed of the impeller 25.

  When evaluating the downflow flow, a tracer is mixed to visualize the flow of water in the tank. It is preferable to use a tracer having a specific gravity close to that of water, such as polystyrene particles. Polyamide-based powders and fluorescent particles can also be used.

  After mixing the tracer, the impeller 25 is driven at a predetermined rotational speed to supply water into the water tank. The water that flows in through the water supply port 31 flows around the specimen 36 and flows out from the drain port 32. The state of the flow around the specimen 36 can be observed from the outside of the water tank 30, whereby the shape of the specimen 36, that is, the shape of the wafer stage 3 can be optimized. If the specimen 36 is moved by driving the actuator 39, it is possible to observe a change in flow when the wafer stage 3 is moved.

  In the above flow evaluation apparatus 200, since the test body 30 is provided at the same height as the water supply port 31, the potential energy of water does not act on the test body 30, and a good downflow flow can be realized. On the other hand, for example, as shown in FIG. 5, the simulated floor 35 is horizontally supported in the water tank via the struts 301, the specimen 36 is provided on the simulated floor, and the water supply port 31 is opened above the specimen 36. When the drain port 32 is opened downward, there are the following problems.

  That is, in the configuration of FIG. 5, not only the kinetic energy due to the flow of water but also the potential energy of water acts on the surface of the specimen 36. Therefore, not only is it difficult to accurately reproduce the downflow flow, but there is also a problem in strength because a large force acts on the surfaces of the specimen 36 and the simulated floor 35. Further, in order to reduce the influence of the flow due to the suction of the drainage port 32 in the vicinity of the specimen, it is necessary to lengthen the length from the simulated floor 35 to the drainage port 32, which increases the size of the device and increases the level. Water must be pumped to the value, and the horsepower of the impeller 25 needs to be increased.

According to 1st Embodiment, there can exist the following effects.
(1) A specimen 36 simulating the wafer stage 3 and a simulated floor 35 simulating the base 8 are installed in the water tank so that the flow field is the same as in the exposure apparatus, and a water supply port 31 facing the specimen 36 is provided. The water was allowed to flow toward the specimen 36 and a tracer was mixed to visualize the flow in the water tank. Thus, the downflow flow can be reproduced in the water tank, the state of the flow around the specimen 36 (wafer stage 3) can be observed, and the downflow airflow in the exposure apparatus can be evaluated.
(2) Since the flow state in the exposure apparatus is reproduced using the flow evaluation apparatus 200 different from the exposure apparatus 100, it is not necessary to mix a tracer or the like in the exposure apparatus to visualize the air flow, and the downflow flow Is easy to visualize.
(3) Since the flow is visualized using the tracer, the flow state of the downflow can be easily grasped. On the other hand, when visualization is performed using, for example, ultrasonic pure water mist in the exposure apparatus, it is difficult to grasp the flow state of the entire apparatus because the mist diffuses in a short time.

(4) Since the downflow is visualized by the flow of water whose kinematic viscosity coefficient ν is significantly smaller than that of air, the representative length d of the specimen 36 and the pseudo floor 35 can be shortened, and the apparatus becomes large. Can be prevented.
(5) Since the specimen 36 is provided at the same height as the water supply port 31 in the water tank, the flow of downflow can be accurately reproduced without being easily influenced by the potential energy of water.
(6) Since the specimen 36 can be moved by the actuator 39, the change in the downflow flow due to the movement of the wafer stage 3 can also be evaluated.
(7) Since the existing circulating water tank can be used for the flow evaluation apparatus 200, it can be configured at low cost.

-Second Embodiment-
A second embodiment of the flow evaluation apparatus according to the present invention will be described with reference to FIG.
FIG. 6A is a front view showing the overall configuration of the flow evaluation apparatus 200 according to the second embodiment, and FIG. 6B is a view b in FIG. 6A. The same portions as those in FIG. 2 are denoted by the same reference numerals, and differences from the first embodiment will be mainly described below.

  As shown in FIG. 6, in the second embodiment, a water tank 30 is provided at the intersection of the horizontal duct portion 21 and the vertical duct portion 24. A water supply port 31 is opened at the center of the bottom surface of the water tank 30 so as to communicate with the vertical duct portion 24, and a drain port 32 is opened at the side surface of the water tank 30 so as to communicate with the horizontal duct portion 21.

  Inside the aquarium, a pseudo floor 35 is fixed and supported substantially horizontally from the inner wall surface of the aquarium 30 via a plurality of struts 41, and passes through a flowing water passage 42 between the struts 41, so that the interior of the aquarium is moved from below to above. Water is flowing. In FIG. 6, the rectifier 34 is not provided downstream of the simulated floor 35, and the drainage port 32 extends from the simulated floor 35 so that suction by the drainage port 32 does not affect the flow of water below the simulated floor 36. The length up to is set.

  As shown in FIG. 6B, a through hole 35a is opened at the center of the simulated floor 35, and the specimen 36 is slidable along the bottom surface of the simulated floor 35 through a strut 37 penetrating the through hole 35a. It is supported. The upper end portion of the strut 37 passes through the support base 38 above the water tank 30 and is connected to the actuator 39. By driving the actuator 39, the specimen 36 can be moved along the bottom surface of the pseudo floor 35 in each direction (front-rear and left-right directions and diagonal directions) indicated by arrows in FIG.

  When evaluating the downflow flow, a tracer is mixed, and the impeller 25 is driven at a predetermined rotational speed to supply water into the water tank. The water that flows in through the water supply port 31 flows around the specimen 36 and flows out of the drain port 32 through the flowing water passage 42. At this time, the state of the flow around the specimen 36 can be observed from the outside of the water tank. Further, if the specimen 39 is moved by driving the actuator 39, it is possible to observe a change in flow when the wafer stage 3 is moved.

  As described above, in the second embodiment, the simulated floor 35 is horizontally arranged in the water tank, the specimen 36 is provided on the bottom surface of the simulated floor 35, and the specimen 36 is supplied from the water supply port 31 facing the specimen 36. The water was made to flow. Thereby, a flow equivalent to the flow of the down flow in the exposure apparatus can be realized in the water tank, and the down flow can be evaluated. Since the specimen 36 is provided on the bottom surface of the simulated floor 35 and water is allowed to flow from below to above, the influence of the potential energy of water is reduced, and a downflow flow can be realized with high accuracy.

  In the above embodiment, the simulated floor 35 is provided adjacent to the specimen 36. For example, as shown in FIG. 7, only the specimen 36 is arranged in the water tank, and the flow around the specimen 36 is changed. You may make it observe. While replacing the wafer stage 3 with the specimen 36 and replacing the base 8 with the simulated floor 35 to observe the downflow flow, other objects placed in the downflow environment are placed on the specimen 36 and the simulated floor 35. Alternatively, the downflow flow may be observed. For example, when evaluating the downflow flow around the reticle stage 2, the visualization test may be performed in the water tank using the specimen 36 simulating the reticle stage 2 as described above. Therefore, the shape of the specimen 36 and the shape of the pseudo floor 35 as the support plate are not limited to those described above.

  As long as the water supply port 31 is provided facing the specimen 36 and the drain port 32 is provided on the opposite side of the water supply port 31 with the specimen 36 interposed therebetween, the shape of the water tank 30 as a liquid container may be arbitrary. A downflow flow may be realized by flowing a liquid other than water into the container. Although the water is circulated in the water tank by driving the impeller 25 to generate a flow equivalent to the downflow space in the exposure apparatus, the flow generating means is not limited to this. Although the specimen 36 is movably supported by the actuator 39 via the strut 37, the distance between the specimen 36 and the wall surface of the water tank 30 is maintained sufficiently so that the flow around the specimen is not obstructed. For example, the support means is not limited to this. The specimen 36 may not be movable. Although the flow in the water tank is visualized by the tracer, other visualization means may be used.

  The flow evaluation apparatus according to the present invention can be applied not only in the exposure apparatus but also in the case of evaluating the flow in other downflow spaces such as in a clean room. When evaluating the flow of the clean room, the floor plate of the clean room may be replaced with the simulated floor 35. That is, the present invention is not limited to the flow evaluation apparatus according to the embodiment as long as the features and functions of the present invention can be realized.

1 is a diagram showing a schematic configuration of a semiconductor exposure apparatus. (A) is a front view which shows the whole structure of the flow evaluation apparatus which concerns on 1st Embodiment, (b) is an arrow b figure of Fig.2 (a). (A) is the perspective view which looked at the rectifier of FIG. 2 from the drain port side, (b) is the perspective view which looked at the water supply port side. The figure which shows the flow of the water in the water tank of FIG. The figure which shows the comparative example of the flow evaluation apparatus of FIG. (A) is a front view which shows the whole structure of the flow evaluation apparatus which concerns on 2nd Embodiment, (b) is an arrow b figure of Fig.6 (a). The figure which shows the modification of this invention.

Explanation of symbols

3 Wafer Stage 8 Base 25 Impeller 30 Water Tank 31 Water Supply Port 32 Drainage Port 34 Rectifier 37 Strut 39 Actuator

Claims (5)

A flow evaluation device for evaluating a flow around an object installed in a downflow space in which air flows from above to below,
A specimen simulating the object;
A water supply opening facing the specimen, and a drain opening provided on the opposite side of the water supply opening across the specimen, and a container capable of observing the inside,
A support means for supporting the specimen in the container;
A flow generating means for circulating a liquid in the container through the water supply port and the drain port, and generating a flow equivalent to the downflow space in the container;
Visualization means for visualizing the flow of liquid in the container. The flow evaluation apparatus according to claim 1,
The flow evaluation apparatus, wherein the water supply port and the drain port are provided at substantially the same height. The flow evaluation apparatus according to claim 2,
A flow evaluation apparatus characterized in that a rectifier for rectifying the flow of liquid is provided between the specimen and the drain port. The flow evaluation apparatus according to claim 1,
The flow evaluation apparatus, wherein the drainage port is provided above the water supply port. In the flow evaluation apparatus according to any one of claims 1 to 4,
In the container, a support plate simulating a floor or base below the object in the downflow space is disposed between the specimen and the drain port,
The said evaluation means supports the said test body so that a movement is possible along the surface of the said support plate, The flow evaluation apparatus characterized by the above-mentioned.

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