JP2004297081A - Exposure system, method of manufacturing device and stage device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the measuring accuracy of a distance between the projection optical system or an original plate and a substrate caused by the deformation of a support means accompanied by the movement of a substrate stage. <P>SOLUTION: In an exposure system where a substrate stage is disposed on a three point-supported first surface plate 7 and the original plate 1 is disposed on a separately supported second surface plate 9, the position of the first surface plate and a measuring point on the first surface plate of the distance between both of the surface plates are set on a straight line which runs through each apex of the triangle constituted by the three points and a median point on a side adjacent thereto. Further, such a measurement is conducted considering the deformation quantity of the first surface plate caused by the movement of the substrate stage measured beforehand at the measuring point. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an exposure apparatus used to manufacture a semiconductor device or the like by exposing a design pattern on a resist on a substrate and a device manufacturing method using the same.

  Conventionally, such an exposure apparatus includes a stepper that sequentially exposes an original pattern onto a plurality of exposure areas on a substrate via a projection optical system while step-moving a substrate such as a wafer, or a projection optical system. There is known a scanning type exposure apparatus for exposing an original pattern onto a substrate by synchronously scanning an original such as a mask and a substrate.

  In recent years, the step movement and the scanning exposure are repeated so that a fine pattern can be exposed to a plurality of regions on the substrate with a high accuracy, so that a fine pattern can be exposed with a higher accuracy. An and scan type exposure apparatus has been proposed. In this exposure apparatus, only a portion relatively close to the optical axis of the projection optical system is used, limited by the slit, so that a fine pattern with higher precision and a wider angle of view can be exposed.

  However, in an exposure apparatus for high-definition exposure such as a step-and-scan type exposure apparatus, in order to sufficiently bring out the performance of the projection optical system and truly improve the exposure accuracy, furthermore, It is necessary to improve the positional consistency between the original and the substrate.

  Therefore, an object of the present invention is to provide a new technique for improving the positional alignment between an original and a substrate in an exposure apparatus and a device manufacturing method using the same.

  Specifically, an object of the present invention is to minimize the deterioration of the measurement accuracy of the positional relationship between the projection optical system or the original and the substrate due to the deformation of the support means, and to perform the measurement of such a positional relationship with higher accuracy. Is to do so.

  An exposure apparatus of the present invention for achieving the above object is an exposure apparatus that exposes a pattern of an original onto the substrate via a projection optical system while moving the substrate by a substrate stage, wherein the substrate stage is provided. A first platen, supporting means for supporting the first platen at three points, a second platen provided with the original plate and the projection optical system, and a distance between the first and second platens. And measuring points on the first platen of the measuring means are, when viewed in the measuring direction, each of the vertices of the triangle formed by the three points and the midpoint of the side adjacent thereto. Are present on a straight line passing through.

  Further, the device manufacturing method of the present invention for achieving the above object is a device manufacturing method of exposing a pattern of an original onto the substrate via a projection optical system while moving the substrate by a substrate stage, A substrate stage is provided on a first surface plate, the original plate and the projection optical system are provided on a second surface plate, the first surface plate is supported at three points, and the first and second surface plates are supported. The distance is measured such that the measurement points on the first surface plate are located on a straight line passing through each vertex of the triangle formed by the three points and the midpoint of the side adjacent thereto when viewed in the measurement direction. The exposure is performed while controlling the relative position between the first and second platens based on the measurement result.

  Further, another exposure apparatus of the present invention for achieving the object is an exposure apparatus that exposes a pattern of an original onto the substrate via a projection optical system while moving the substrate by a substrate stage, A first platen provided with a substrate stage, support means for supporting the first platen at three points, a second platen provided with the original plate and the projection optical system, and the first and second plates; Measuring means for measuring a distance between the boards, wherein the measuring means calculates a previously measured amount of deformation of the first platen due to movement of the substrate stage at a measurement point on the first platen. It is characterized in that the distance is measured in consideration of the above.

  Another device manufacturing method of the present invention for achieving the above object is a device manufacturing method for exposing a pattern of an original onto the substrate via a projection optical system while moving the substrate by a substrate stage. Providing the substrate stage on a first platen, supporting the original plate and the projection optical system on a second platen, supporting the first platen at three points, and providing the first and second platens. The distance between the first and second measurement points on the first surface plate is measured in consideration of the previously measured deformation amount of the first surface plate due to the movement of the stage. The exposure is performed while controlling the relative position between the second platens.

  In addition, a stage device of the present invention for achieving the above object has a surface plate supported at three points, a stage provided on the surface plate, and a measuring means for measuring a position of the surface plate in a supporting direction. Wherein the measuring point of the position of the measuring means on the surface plate is, when viewed in the measuring direction, a midpoint of each vertex of the triangle formed by the three points and a side adjacent thereto. And exists on a straight line passing through.

  According to the present invention, in an exposure apparatus in which a substrate stage is mounted on a first surface plate supported by three points and an original stage and a projection optical system are mounted on a second surface plate supported by three points, Since the measurement points of the position of the supported surface plate and the distance to it are located on a straight line passing through each vertex of the triangle constituting the three points and the midpoint of the adjacent side, the position of the substrate stage Measurement can be performed with high accuracy by measuring a point at which the surface plate undergoes little deformation due to movement as a measurement point. Alternatively, such measurement can be performed with high accuracy by taking into account the previously measured deformation of the surface plate due to the movement of the substrate stage at the measurement point.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram schematically showing a side view of an exposure apparatus according to an embodiment of the present invention, and FIG. 2 is a perspective view showing an appearance of the exposure apparatus. As shown in these drawings, this exposure apparatus projects a part of the pattern of an original on a reticle stage 1 onto a wafer on an XY stage 3 via a projection optical system 2, and The reticle and the wafer are relatively synchronously scanned in the Y direction to expose the reticle pattern to the wafer, and this scanning exposure is performed on a plurality of regions on the wafer while interposing a step movement for repeated execution. This is a step-and-scan type exposure apparatus.

  The reticle stage 1 is driven in the Y direction by the linear motor 4, the X stage 3a of the XY stage 3 is driven in the X direction by the linear motor 5, and the Y stage 3b is driven in the Y direction by the linear motor 6. ing. The synchronous scanning of the reticle and the wafer is performed by driving the reticle stage 1 and the Y stage 3b at a constant speed ratio (for example, 4: 1) in the Y direction. The step movement in the X direction is performed by the X stage 3a.

  The XY stage 3 is provided on a stage base 7, and the stage base 7 is supported on a floor or the like at three points via three dampers 8. The reticle stage 1 and the projection optical system 2 are provided on a lens barrel base 9, and the lens barrel base 9 is supported on a base frame 10 via three dampers 11 and columns 12. The damper 8 is an active damper for actively damping or removing vibrations in six axial directions, but a passive damper may be used or may be supported without a damper.

  FIG. 3 shows the positional relationship between the damper 11 or the support 12, the scanning direction during scanning exposure, the projection optical system 2 and the exposure light when viewed from above the apparatus. As shown in the figure, three support points of the lens barrel base 9 by the damper 11 and the support column 12 form an isosceles triangle, and a straight line 17 connecting a point 16 where the isosceles 14 and 15 intersect and a center of gravity is provided. , The scanning direction Y is parallel, and the center of gravity 18 and the center of gravity 19 of the projection optical system 2 substantially match. Reference numeral 20 in FIG. 3 is a cross section of the exposure light formed into a slit shape. The longitudinal direction of the slit shape is a direction (X direction) perpendicular to the scanning direction. Two of the three dampers 11 are located at the front of the device, and the other one is located at the back of the device. Then, the path for carrying the wafer into the apparatus is set from the front side of the apparatus through two columns 12 arranged at the front of the apparatus.

  The exposure apparatus further includes a distance measuring means 13 such as a laser interferometer or a micro encoder for measuring the distance between the lens barrel base 9 and the stage base 7 at three points. As shown in FIG. 5, the three measurement points P in FIG. 5, when viewed in the measurement direction, are defined by the vertices of the triangle formed by the three support points of the surface plate 7 by the damper 8 and the midpoint of the side adjacent thereto. Exists on a straight line that passes.

  Alternatively, the distance may be measured in consideration of the previously measured deformation amount of the stage base 7 due to the movement of the XY stage 3 at these measurement points.

  In this configuration, when the wafer is loaded onto the XY stage 3 via the transport path between the two columns 12 at the front of the apparatus by the transport means (not shown), and the predetermined alignment is completed, the exposure apparatus starts scanning. While repeating the exposure and the step movement, the reticle pattern is exposed and transferred to a plurality of exposure regions on the wafer. At the time of scanning exposure, the reticle stage 1 and the Y stage 3b are moved at a predetermined speed ratio in the Y direction (scanning direction) to scan a pattern on the reticle with slit-like exposure light, and use the projected image to scan the wafer. To expose a pattern on the reticle to a predetermined exposure area on the wafer. When the scanning exposure for one exposure area is completed, the X stage 3a is driven in the X direction to move the wafer stepwise, thereby positioning the other exposure area with respect to the start position of the scanning exposure and performing the scanning exposure. Note that a combination of the step movement in the X direction and the movement for scanning exposure in the Y direction allows each exposure area to be sequentially and efficiently exposed to a plurality of exposure areas on the wafer. The arrangement, the scanning direction for either positive or negative Y, the order of exposure to each exposure area, and the like are set.

  At the time of scanning exposure, as the reticle stage 1 moves, the inclination and the deformation state of the lens barrel base 9 change due to the movement of the center of gravity. However, as described above, the support points of the lens barrel base 9 form an isosceles triangle, the scanning direction Y is parallel to the straight line 17, and the center of gravity of the isosceles triangle and the center of gravity of the projection optical system 2 Coincide with each other, so that the center of gravity of the reticle stage 1 also passes substantially on the straight line 17. Therefore, the tilt of the lens barrel base 9 due to the movement of the reticle stage 1 is only in the Y (Z) direction and not in the X direction. The deformation amount of the lens barrel base 9 is symmetrical about the straight line 17. Therefore, even with this deformation, the slit shape 20 of the exposure light is perpendicular to the scanning direction. Therefore, even if the exposure light is inclined in the Y direction, for example, simply adjusting the wafer position in the Z direction eliminates the influence of the inclination. Can be. On the other hand, when the lens barrel base 9 is inclined with respect to the X direction, it is very difficult to eliminate the influence of the inclination because the slit shape 20 extends in the X direction.

  Further, since the lens barrel base 9 is supported at three points, the relationship between the position of the reticle stage 1, the amount of deformation of each point of the lens barrel base 9, and the position of each support point is uniquely determined. Better reproducibility to deformation than four-point support. Therefore, when the deformation of the lens barrel base 9 due to the movement of the reticle stage 1 is considered or corrected, these can be performed with high accuracy. For example, as shown in FIG. 1, whether or not the wafer is located at the focus position of the projection optical system 2 is determined by emitting light from an oblique direction to the wafer by the light projecting means 21 fixed to the lens barrel base 9. Irradiation can be performed by detecting the position of the reflected light with the light receiving means 22. At this time, the focus position can be accurately detected in consideration of the accurate deformation amount of the lens barrel base 9. . Also, the measurement by the laser interferometer 23 for detecting the position of the wafer in the X, Y, and θ directions can be accurately performed similarly in consideration of the deformation amount of the lens barrel base 9.

  Further, in the scanning exposure or the step movement, the lens barrel base 9 and the stage base 7 are tilted with the movement of the reticle stage 1 and the XY stage 3, so that it is necessary to correct this. For this purpose, the distance between the lens barrel base 9 and the stage base 7 is measured by the distance measuring means 13 near the three support points. At this time, the measurement points on the stage base 7 are on a straight line that passes through each vertex of the triangle formed by the three support points and the midpoint of the side adjacent thereto in the measurement direction. At these measurement points, the amount of deformation associated with the movement of the reticle stage 1 or the X / Y stage 3 is negligible, so that measurement can be performed without considering the amount of deformation.

  On the other hand, if the deformation amount at the measurement point is not negligible, the deformation amount is measured in advance corresponding to the position of the reticle stage 1 or the XY stage 3, and the deformation amount is considered. The accurate distance between the barrel base 9 and the stage base 7 can be measured. In this case, as described above, since the three-point support is used, the reproducibility of the deformation amount is good, and the deformation amount can be accurately reflected.

  FIGS. 4A and 4B are graphs showing an example of a temporal change of the moving speed of the X stage 3a and the Y stage 3b in the step movement and the scanning exposure, respectively. When acceleration of the Y stage is started, the Y stage moves at a constant speed of 100 mm / sec for 0.375 seconds after an acceleration period of 0.051 seconds and a settling time of 0.05 seconds. Exposure is performed during this constant speed movement period. After this exposure period, the Y stage is decelerated and the X stage is started to accelerate to perform a step movement. When the step movement is completed, acceleration of the Y stage is started again in the same manner. In this manner, the movement of the X and Y stages is repeated to sequentially scan and expose the reticle pattern to a plurality of exposure areas.

  The weight of the X stage is 30 kg and the weight of the Y stage is 60 kg, and acceleration and deceleration as shown in FIG. 4 are performed. At that time, the maximum acceleration of the X and Y stages is 0.2 G, the maximum scan speed is 100 mm / sec, the maximum step speed is 350 mm / sec, the settling time is 0.15 sec, the angle of view of the exposure (exposure in each exposure area) Assuming that the size of the range is 32.5 × 25 mm, the scan distance is 37.5 (32.5 + 5) mm, and the thrust constant of the linear motor driving the X and Y stages is 20 N / A, the scan time and the step time , The duties Dy and Dx at the time of acceleration / deceleration are

であり、ＹステージおよびＸステージにおける各発熱量Ｑ_１ｙおよびＱ_１ｘは、

And the calorific values Q _1y and Q _1x in the Y stage and the X stage are

となり、発熱量の合計は２４．１２［ｗ］である。一方、仮に、Ｘステージを走査方向に駆動させ、Ｙステージでステップ移動を行うとし、その他の点については、上述と同様であるとすれば、そのときのＸおよびＹ各ステージにおける発熱量Ｑ_２ｙおよびＱ_２ｘは、

And the total calorific value is 24.12 [w]. On the other hand, if it is assumed that the X stage is driven in the scanning direction and the Y stage performs the step movement, and the other points are the same as described above, the heat generation amount Q _2y in each of the X and Y stages at that time. And Q _2x are

であり、発熱量の合計は、３５．１４［ｗ］となる。したがって、重い下側のＹステージをデューティの少ないスキャン動作に使用することにより、発熱量を抑えることができる。また、このように、軽い上側のＸステージの駆動方向を走査方向と直交する方向とし、そのＸステージにより、レチクルステージ１における走査方向に垂直な成分の駆動誤差の補正やオフセットへの追込み駆動を行うことにより、これら補正等の精度を向上させることができる。したがって、レチクルステージ１を走査方向のみの１軸方向の駆動手段のみで構成することも可能となる。

And the total amount of heat generation is 35.14 [w]. Therefore, the heat generation amount can be suppressed by using the heavy lower Y stage for the scan operation with a small duty. Further, as described above, the driving direction of the light upper X stage is set to a direction orthogonal to the scanning direction, and the X stage is used to correct a driving error of a component perpendicular to the scanning direction in the reticle stage 1 and to drive the offset to the offset. By doing so, the accuracy of these corrections and the like can be improved. Therefore, the reticle stage 1 can be constituted only by the driving means in one axis direction only in the scanning direction.

  Next, an embodiment of a device production method using the above-described exposure apparatus will be described.

  FIG. 6 shows a flow of manufacturing micro devices (semiconductor chips such as ICs and LSIs, liquid crystal panels, CCDs, thin-film magnetic heads, micro machines, etc.). In step 1 (circuit design), the circuit of the semiconductor device is designed. Step 2 is a process for making a mask on the basis of the circuit pattern design. On the other hand, in step 3 (wafer manufacturing), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is referred to as a pre-process in which an actual circuit is formed on the wafer by lithography using the prepared mask and wafer. The next step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer produced in step 4, and includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). including. In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

  FIG. 7 shows a detailed flow of the wafer process. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition. Step 14 (ion implantation) implants ions into the wafer. In step 15 (resist processing), a photosensitive agent is applied to the wafer. Step 16 (exposure) uses the above-described exposure apparatus to print and expose the circuit pattern of the mask onto the wafer. Step 17 (development) develops the exposed wafer. In step 18 (etching), portions other than the developed resist image are removed. Step 19 (resist stripping) removes unnecessary resist after etching. By repeating these steps, multiple circuit patterns are formed on the wafer.

  By using the manufacturing method of this embodiment, it is possible to manufacture a highly integrated semiconductor device, which was conventionally difficult to manufacture, at low cost.

FIG. 1 is a diagram schematically illustrating a state of an exposure apparatus according to an embodiment of the present invention when viewed from a side. FIG. 2 is a perspective view illustrating an appearance of the exposure apparatus of FIG. 1. FIG. 2 is a diagram showing a positional relationship between a damper or a support, a scanning direction at the time of scanning exposure, a projection optical system, and exposure light of the apparatus of FIG. 1 when viewed from above the apparatus. 2 is a graph illustrating an example of a temporal change in the moving speed of an X stage and a Y stage during step movement and scanning exposure in the apparatus of FIG. 1. FIG. 2 is a diagram illustrating a positional relationship between a support point of a stage base and a measurement point of the stage base in the apparatus of FIG. 1. It is a figure showing the flow of manufacture of a micro device. FIG. 7 is a diagram showing a detailed flow of a wafer process in FIG. 6.

Explanation of reference numerals

1: reticle stage, 2: projection optical system, 3: XY stage, 4: linear motor, 3a: X stage, 3b: Y stage, 6: linear motor, 7: stage base, 8: damper, 9: Lens barrel base, 10: base frame, 11: damper, 12: support, 13: distance measuring means, 18, 19: center of gravity, 20: cross section of exposure light, 21: light projecting means, 22: light receiving means, 23: Laser interferometer.

Claims (5)

  An exposure apparatus for exposing a pattern of an original onto the substrate via a projection optical system while moving the substrate by a substrate stage, comprising: a first surface plate provided with the substrate stage; Supporting means for supporting at three points, a second platen provided with the original plate and the projection optical system, and measuring means for measuring a distance between the first and second platens; The exposure apparatus according to claim 1, wherein the measurement points on the first platen are located on a straight line passing through each vertex of the triangle formed by the three points and the midpoint of the side adjacent thereto when viewed in the measurement direction. . A device manufacturing method for exposing a pattern of an original onto the substrate via a projection optical system while moving the substrate by a substrate stage, wherein the substrate stage is provided on a first surface plate, and the original and the projection optical system are provided. A system is provided on a second platen, the first platen is supported at three points, and the distance between the first and second platens is determined by measuring points on the first platen in the measurement direction. That is, the three points are measured so as to lie on a straight line passing through each vertex of the triangle formed by the three points and the midpoint of the side adjacent thereto, and the distance between the first and second platens is determined based on the measurement result. Performing a light exposure while controlling a relative position of the device. An exposure apparatus for exposing a pattern of an original onto the substrate via a projection optical system while moving the substrate by a substrate stage, comprising: a first surface plate provided with the substrate stage; Support means for supporting at three points, a second surface plate provided with the original plate and the projection optical system, and measurement means for measuring a distance between the first and second surface plates, wherein the measurement means comprises: The exposure is characterized in that the distance is measured in consideration of a previously measured deformation amount of the first surface plate due to movement of the substrate stage at a measurement point on the first surface plate. apparatus. A device manufacturing method for exposing a pattern of an original onto the substrate via a projection optical system while moving the substrate by a substrate stage, wherein the substrate stage is provided on a first surface plate, and the original and the projection optical system are provided. The system is supported on a second platen, the first platen is supported at three points, and the distance between the first and second platens is measured in advance at a measurement point on the first platen. Measuring the amount of deformation of the first surface plate due to the movement of the stage, and performing the exposure while controlling the relative position between the first and second surface plates based on the measurement result. Device manufacturing method. A stage apparatus comprising: a surface plate supported at three points; a stage provided on the surface plate; and measuring means for measuring a position of the surface plate in a supporting direction. A stage apparatus characterized in that a measurement point at a position on the board, when viewed in the measurement direction, exists on a straight line passing through each vertex of the triangle formed by the three points and the midpoint of a side adjacent thereto.

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