JPH1174186A - Positioning device, exposure system, and manufacture of device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a time required for the movement of a stage by a method, wherein a change of a substrate in plane orientation is retained in a control means, and a rotary table is corrected on rotation around an X and a Y-axis based on the above change independent of the rotation at a time, when final positioning is carried out when a plane orientation detection means detects the plane orientation of a substrate. SOLUTION: Various step movements, a relative pitching between a stage platen 1 and an X-stage 7, and a relative pitching between the X-stage 7 and a fine adjustment stage 9 corresponding to the direction of movement are previously calculated or measured in factory tests or the like and retained as a table or a function from in a reference table 18. Then, a control box 16 drives z-actuators 15a and 15b of the fine adjustment stage 9 correcting the fine adjustment stage 9 on drive, independent of drive at the time when final positional is completed so as to make the inclination of a wafer 10 nearly in match with an image plane at that timing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning apparatus used for an exposure apparatus for forming a pattern on a flat object such as a semiconductor wafer or a liquid crystal panel, and more particularly, to a high-density integrated circuit such as a semiconductor memory and an arithmetic element. The present invention relates to a positioning apparatus capable of accurately holding a position of an object to be exposed such as a wafer on which a circuit pattern is to be printed in manufacturing a chip and performing high-precision exposure.

[0002]

2. Description of the Related Art Conventionally, a positioning device used for an exposure apparatus or the like generally has an XY stage for moving and positioning in an X-axis and a Y-direction on an XY plane, and is mounted on the XY stage and is for movement and positioning in a Z-direction. , A fine movement stage for performing rotation / positioning with respect to the Z axis and rotation / positioning for both X and Y axes, and a surface position detecting device for detecting the inclination of the exposure area of the wafer. Thereby, the wafer is moved at a high speed within the XY plane by a predetermined distance, the surface position of the exposure area of the wafer is detected and corrected by the fine movement stage, and then the exposure operation is performed. Baking is performed.

[0003]

However, in the above conventional example, pitching (pitch) in the traveling direction cannot be avoided at the start and end of the step operation. In particular, since the pitching at the end of the step operation acts so that the wafer surface is inclined with respect to the exposure surface, the detection of the surface position must be started after the convergence of the pitching. In addition, the reference surface itself has surface distortion due to the limit of processing accuracy, and the stage with a certain weight moves on it, so the deformation due to the moving load can not be ignored, so the movement to the predetermined position is completed After that, the detection of the surface position had to be started. Then, the fine movement stage was driven so as to correct the measured surface position, and the exposure operation could be started only after the fine movement stage was completed. That is,
The movement of the XY stage, the measurement of the wafer surface position, and the correction drive of the fine movement stage could not be performed in parallel, and these operations had to be performed sequentially. As a result, the time required for the stage movement operation including the fine movement was required. However, there has been a problem in that the length of the system becomes longer, and eventually the throughput of the entire apparatus is deteriorated.

In order to address the above problems, an angular displacement sensor for detecting the inclination of the fine movement stage with respect to the reference plane, an angular accelerometer and an angular velocity meter for detecting a change in the inclination of the fine movement stage, etc. It is also conceivable to correct the effect of pitching by performing tilting control of the fine movement stage based on the signal.However, by attaching a detector, the weight of the moving part increases and the speed of the stage increases. However, there is a problem in that the step time is increased and the cost is increased due to the loss of performance, the addition of the detection operation of the detection means, the calculation operation, and the communication operation to the control means.

An object of the present invention is to solve the problems in the above-described conventional example, and to reduce the time required for the stage movement operation including fine movement without adding a special detecting means, and to provide an exposure apparatus. It is an object of the present invention to provide a positioning device that contributes to an improvement in the throughput of the entire device by using the positioning device.

[0006]

According to the present invention, there is provided an XY table in which a holding surface for holding a substrate is movable in each of XY directions with respect to a surface plate. A rotating table mounted on the substrate and capable of rotating the substrate about each of the XY axes and movable in the Z direction; control means for controlling the drive of the XY table and the rotating table; and a surface position for detecting a surface position of the substrate In the positioning device provided with a detecting means, the amount of change in the surface position of the substrate generated when the XY table is moved is held in the control means in advance, and the amount of change in the surface position detected by the surface position detecting means is detected using the control means. The rotation amount of the rotary table around the XY axes is corrected and driven independently of the rotation amount at the time of final positioning.

The control means calculates the amount of change in the surface position of the substrate caused by the movement of the XY table.
XY according to the moving amount and / or moving direction of the table
Numerical values relating to the rotation angle and the Z-direction displacement in the rotation direction about each axis are calculated or measured in advance, and are stored as a table or function using the movement amount and / or movement direction of the XY table as variables. Alternatively, a correction value of the rotation angle around each axis of the XY and the displacement in the Z direction according to the XY coordinates of the XY table is calculated or measured in advance, and the correction values are obtained using the XY coordinates of the XY table as variables. Or keep it as a function.

[0008]

The positioning apparatus of the present invention is suitably applied to a step-and-repeat type exposure apparatus. In this case, the pitching amount of the stage and the deformation amount of the reference plane are obtained in advance, and the height and inclination change values in the exposure area of the substrate caused by the pitching amount are held, and the fine movement stage is measured at the moment when the surface position is measured. By correcting and driving the tilting angle independently of the tilting angle at the time of final positioning, the above-mentioned surface position detecting device can accurately detect the tilting angle even when the stage is still moving without adding any special detecting means. Detection. The above-described change values of the height and the inclination in the exposure area of the substrate are stored as a table corresponding to the distance of the step movement or a table corresponding to the XY coordinates of the stage.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of a positioning apparatus for an exposure apparatus according to one embodiment of the present invention. In the figure, 1 is a stage base, 2 (2a, 2b) is a Y linear motor for driving in the Y direction, 3 is a Y guide for performing a linear motion guide in the Y direction, and 4 (4a, 4b) is a Y direction. And a Y stage on which an X guide described later is mounted. 5 is X
An X linear motor 6 for driving in the direction, an X guide 6 for performing a linear motion guide in the X direction, and an X stage 7 for moving in the X direction. Since these are connected to the Y stage 4 (4a, 4b), the X stage 7 can be freely moved in both the X direction and the Y direction. Reference numeral 8 denotes an air pad, which is used to move the Y stage 4 (4a, 4b) and the X stage 7 to several μm to several tens μm with respect to the stage base 1.
Is emerging. Reference numeral 9 denotes a fine movement stage movable in the Z direction and a rotation direction around each of the X, Y, and Z axes, and reference numeral 10 denotes a wafer suction-fixed on the fine movement stage 9 by vacuum suction. Reference numeral 11 denotes a light irradiation unit for measuring the surface position of the wafer 10, and 12 denotes a reflection mirror for guiding the light to an exposure area of the wafer 10 and its periphery. 13 is a surface position detecting means for detecting the surface position and inclination of the exposure area of the wafer 10,
Reference numeral 14 denotes a reflection mirror for guiding the reflection of the light beam for measuring the surface position from the wafer 10 to the surface position detecting means 13.

FIG. 2 is a diagram showing the operation of the apparatus shown in FIG. In the figure, the same reference numerals as those in FIG. 1 indicate the same elements. In FIG. 2, reference numeral 111 denotes a light source such as a white lamp, and 112 denotes a collimator lens which emits a light beam from the light source 111 as a parallel light beam having a substantially uniform cross-sectional intensity distribution. Reference numeral 113 denotes a prism-shaped slit member having a plurality of openings (for example, five pinholes).
have. Reference numeral 114 denotes a light projecting lens system, which is composed of both telecentric systems, and guides a plurality of light beams passing through a plurality of openings of the slit member 113 to a plurality of measurement points on the surface of the wafer 10 via the mirror 12. . From these members 111, 112, 113, 114, the light irradiation means 1
1 is configured. Reference numeral 131 denotes a light receiving lens, which is formed of both telecentric systems and receives a plurality of measurement points from the wafer 10 via the mirror 14. Reference numeral 132 denotes a plurality of pinhole images formed for each measurement point on the wafer 10 by the light receiving lens 131. Reference numeral 133 denotes a plurality of correction optical systems (represented for simplicity in the figure) for re-imaging light beams from the plurality of pinhole images 132 on a detection surface of a photoelectric conversion unit to be described later so as to have the same size. And only one is described). Reference numeral 134 denotes a photoelectric conversion unit such as a two-dimensional CCD. These members 131, 133, and 134 constitute the surface position detecting means 13. 15a,
Reference numeral 15b denotes a Z actuator, which also serves as a tilting actuator. That is, by relatively increasing or decreasing the displacements in the respective Z directions, displacements in the rotation directions (tilting) around the X and Y axes can be obtained at the same time. Further, in the figure, two actuators are shown for simplicity, but at least three or more actuators are necessary to make the actuator movable in the rotation directions about the X and Y axes. A control box 16 controls the entire stage. Reference numeral 17 denotes a focus control box for obtaining the height and inclination of the exposure area of the wafer 10 based on the detection signal of the surface position detection means 13. Reference numeral 18 denotes a reference table that holds a relationship between the step amount and the XY coordinates and the amount of change in the inclination of the wafer 10 with respect to the image plane, which is obtained in advance.

Next, the operation of the apparatus shown in FIGS. 1 and 2 according to the present invention will be described in order. For example, when performing a step operation in the X direction in the figure, the X linear motor 5
The X stage 7 moves linearly along the X guide 6 and moves a predetermined distance, and then the X linear motor 5 applies a braking force to the X stage 7 and stops at a predetermined position. I do. Next, the light beam emitted from the light source 111 is emitted as a substantially parallel light beam by the collimator lens 112, passes through the slit member, becomes a plurality of independent measurement light beams, and passes through the light projecting lens system 114 and the mirror 12 to the wafer 10. Is projected on the exposure area of the above and the measurement points around it. The plurality of measurement lights are reflected on the surface of the wafer 10 and are reflected by a mirror.
A plurality of pinhole images 132 are formed for each measurement point by the light-receiving lens 131 and the light-receiving lens 131, and are re-imaged on the photoelectric conversion means 134 by the correction optical system 133, and the photoelectric conversion means 134 The signal is converted into a plurality of electric signals as signals relating to the height of each point. These signals are input to the focus control box 17,
The height of each measurement point with respect to a given reference plane is determined,
Next, the height of the exposure area with respect to the reference plane is calculated from the average value of the height of each measurement point, and the rotation direction (tilting) around the X and Y axes of the exposure area is calculated from the relative difference between the heights of each measurement point. The displacement or tilt is calculated. In this manner, the inclination of the exposure area with respect to the image plane of the projection lens (not shown) due to the thickness variation, the wedge shape, and the warpage of the wafer 10 is obtained.

However, the generated force F of the X linear motor 5
Since the action line does not always coincide with the position G of the center of gravity of the X stage 7, it acts as a moment force during acceleration and deceleration as shown in FIG. On the other hand, since the air pad 8 has a characteristic that the levitation force increases when the gap with the stage base 1 narrows in principle and decreases when the gap widens, the restoration of restoring the tilt of the X stage 7 to the horizontal position is performed. Acts as a force. That is, when the X stage 7 is accelerated or decelerated, a pitching angle is generated at which the moment force of the X linear motor 5 and the restoring force of the air pad 8 are balanced.

A similar phenomenon occurs with respect to the relative displacement of the fine movement stage 9 with respect to the X stage according to the same principle.
That is, the fine movement stage 9 is generally held by feedback control so as to always maintain a constant inclination even while the stage 7 is moving, while the moment force generated by the X linear motor 5 when the X stage 7 is accelerated or decelerated. This moment force acts as a larger moment force because it is structurally separated from the center of gravity of the fine movement stage 9 and the line of action of the linear motor 5. Therefore,
Here, a pitching angle occurs at which the moment force and the restoring force by the feedback control are balanced.

[0014] These phenomena occur exactly in the same manner when a step operation in the Y direction is performed. In addition, since the surface of the stage base is unavoidable due to the limitation of processing accuracy, the inclination of the upper surface differs slightly depending on the position of the stage. Naturally, the X stage based on the stage base has a certain inclination error. become.

Further, since each of the X stage, the Y stage and the fine movement stage having a certain weight moves on the stage base, surface distortion due to the moving load cannot be avoided. Therefore, in the conventional apparatus, the wafer 1
In order to measure the inclination of the exposure area of 0, it is necessary to complete the step operation and eliminate the pitching of the X stage 7 with respect to the stage base 1 and the pitching of the fine movement stage 9 with respect to the X stage 7. Stage surface plate 1
Since there is a surface distortion due to the processing accuracy and a surface distortion due to a moving load, the position at which the inclination is measured must coincide with the exposure position, and the step operation must be completed after all. Alternatively, even when the step operation is not completely completed, it is necessary to measure the inclination slightly before the completion of the step operation, where these measurement errors are expected to be within a predetermined allowable value. In other words, the movement of the XY stage, the measurement of the wafer surface position, and the correction drive of the fine movement stage cannot be performed in parallel, and must be performed sequentially, so that the time required for the stage movement operation becomes longer. There is a problem that the time required from the start to the start of the exposure operation becomes longer, and the throughput of the entire apparatus is deteriorated.

In order to cope with the above problems, an angular displacement sensor for detecting the inclination of the X stage 7 and the fine movement stage 9 with respect to the reference plane is provided, and the angle for detecting the change in the inclination of the fine movement stage is provided. A method of providing an accelerometer, a gyro, or the like, and correcting the measured value of the tilt of the wafer 10 based on the signal is conceivable. However, by attaching a detector, the weight of the moving unit increases, and the speed of the stage increases. However, there is a problem that the detection time of the detection means, the calculation operation, and the communication operation to the control means are added, so that the step time becomes longer and the cost increases. Also in this case, it is difficult to detect the inclination caused by the processing accuracy of the stage base and the inclination caused by the deformation of the stage base due to the moving load.

Incidentally, the stage base 1 and the X stage 7
The relative pitching amounts to the acceleration and the acceleration time by the linear motor, the restoring force and the viscous resistance by the air pad, the X stage 7 and the Z linear motor 15a, 1
5b, the position of the center of gravity and the moment of inertia of the moving body composed of the fine movement stage 9 and its mount. The values other than the acceleration and the acceleration time are values specific to the device.
Further, since the acceleration and the acceleration time by the linear motor are determined by the step moving amount, the pitching amount and the damping characteristic can be uniquely obtained in advance if only the step moving amount is known. Similarly, the relative pitching amount between the X stage 7 and the fine movement stage 9 includes the acceleration and acceleration time by the linear motor, the control characteristics such as the restoring force by the feedback control, the position of the center of gravity of the fine movement stage 9 and its mounted object. And the moment of inertia, so if this is also known,
The pitching amount and the attenuation characteristic can be uniquely obtained in advance. Furthermore, if the inclination of the X stage 7 due to the surface distortion due to the processing accuracy of the stage base 1 or the surface distortion due to the moving load is determined in advance by measurement or the like, it is determined only by the position of the XY stage. If you know it, you can find it uniquely.

The present invention focuses on this point.
The inclination of the wafer 10 is measured at a relatively early stage during the movement of the stage, for example, at a predetermined measurement timing such as a constant speed movement stage or a deceleration stage, and the pitching amount at the measurement timing is determined in advance by the step movement amount, the movement direction, and the XY. By holding in the form of a table or a function relating to at least one of the coordinates, the tilting drive of fine movement stage 9 at this measurement timing is corrected and driven independently of the tilting drive amount at the time of final positioning, The purpose of the present invention is to cancel the influence of the pitching at the moment of measuring the inclination, and to shorten the entire step time while maintaining the measurement accuracy.

That is, for example, the stage base 1 and the X stage 7 in accordance with various step moving amounts and moving directions at predetermined measurement timings of the inclination of the exposure area in the stage constant speed moving stage and the decelerating stage. The relative pitching amount and the relative pitching amount between the X stage 7 and the fine movement stage 9 are calculated in advance, or each of the above-mentioned pitching amounts is measured at the time of a factory inspection or the like,
The information is stored in the reference table 18 in the form of a table or a function. Next, similarly, at the time of a factory inspection, etc., the inclination of the X stage 7 due to the surface distortion due to the processing accuracy of the stage base 1 and the surface distortion due to the moving load according to the XY coordinates at the measurement timing of the inclination of the exposure area is measured. Then, it is stored in the reference table 18 in the form of a table or the like. During the actual operation of the apparatus, during the movement of the stage, for example, at the predetermined measurement timing of the inclination of the exposure area in the constant speed movement stage or the deceleration stage, the held numerical values related to the pitching amount at the predetermined measurement timing are obtained from the reference table 18. Notify the control box 16. This may be performed each time step driving is performed, or may be performed collectively at the start of a series of exposure operations in advance. The control box 16 drives the Z actuator 15 of the fine movement stage 9 so as to correct the pitching amount, and is independent of the driving amount at the time of completion of the actual positioning so that the inclination of the wafer 10 at that timing substantially matches the image plane. Is driven for correction. This correction drive may be performed at the start of the step, at a predetermined time during the step, or immediately before measuring the inclination of the exposure area of the wafer 10. Next, the inclination of the exposure area of the wafer 10 is measured by the above-described series of operations at the predetermined timing. This allows
Since the influence of the pitching is avoided even before the stage is completely stopped, an accurate measurement value can always be obtained for the inclination of the exposure region of the wafer 10. In addition, since the correction drive operation performed by the fine movement stage 9 to cancel the effects of various pitching needs to be performed only for a limited time during the measurement of the inclination of the exposure region, the correction drive operation is not always performed dynamically. Can be realized very easily. Next, the focus control box 17 notifies the control box 16 of the obtained inclination value. The control box 16 calculates a drive amount of the Z actuators 15a and 15b based on the measured inclination to calculate a drive amount of the Z actuators 15a and 15b so that the inclination of the exposure area of the wafer 10 at the position where the exposure operation is performed is accurately matched with the image plane of the projection lens. give. The Z actuators 15a and 15b change the inclination of the fine movement stage 9 so that the exposure area of the wafer 10 at the position where the exposure operation is performed completely coincides with the image plane of the projection lens. However, at this stage, since various pitching due to the movement of the stage as described above still remains, it is not always necessary that the height and inclination of the wafer 10 at that moment coincide with the image plane. Then, the movement of the X stage 7 is completed immediately before and after reaching the target position, that is, the position where the exposure operation is to be performed, and the setting is completed. Thereafter, the exposure operation is immediately performed, and after the completion, the next step operation is started. In other words, the movement of the XY stage, the measurement of the wafer surface position, and the correction drive of the fine movement stage can be performed in parallel. As a result, the time required for the movement of the stage including the fine movement is reduced, and the overall throughput of the apparatus is improved. Can be done.

In the above example, the relative pitching amount between the stage base 1 and the X stage 7 and the relative pitching amount between the X stage 7 and the fine movement stage 9 are determined by using a table corresponding to the step moving amount and the moving direction. Alternatively, the table is held in the form of a function, but the table or function may be added with the XY coordinates of the stage. In this case, due to uneven thrust generated by each linear motor and a difference in thrust balance depending on the position, a more accurate correction operation that takes into account the change in the pitching state based on the XY coordinates can be expected.

The above-described various measurements may be performed when the device is installed on site, or as one of the initial operation sequences in actual operation. Thereby, a more accurate correction operation can be performed in consideration of the installation state of the apparatus.

Further, in the above example, an example has been described in which the pitching amount for each item is individually calculated or measured and held, but based on the individually calculated or measured value, the wafer is finally determined. A correction value to be corrected for the surface position measurement value of the surface may be calculated and stored in the correction table 18. Also, instead of calculating or measuring the pitching amount individually, the wafer surface position with respect to various step amounts and XY coordinates during an initial operation sequence at the time of factory inspection, on-site installation of the device, or in actual operation. The measurement may be collectively performed as a steady error of the measurement inclination, and may be held. In this case, since the number of measurement items is reduced and the amount of data to be stored can be reduced, a simpler correction operation can be realized.

[0023]

[Embodiment of Device Production Method] Next, an embodiment of a device production method using the above-described exposure apparatus or exposure method will be described. FIG. 3 shows a micro device (a semiconductor chip such as an IC or an LSI, a liquid crystal panel, a CCD, a thin film magnetic head,
2 shows a flow of manufacturing a micromachine or the like. Step 1
In (Circuit Design), a device pattern is designed. Step 2 is a process for making a mask on the basis of the designed pattern. Step 3 (wafer manufacturing)
Then, a wafer is manufactured using a material such as silicon or glass. Step 4 (wafer process) is called a pre-process,
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. 4 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. In step 14 (ion implantation), ions are implanted into the wafer. Step 15
In (resist processing), a photosensitive agent is applied to the wafer. Step 16 (exposure) uses the exposure apparatus having the above-described positioning device 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. In step 19 (resist stripping), unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

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

[0026]

As described above, according to the present invention,
When measuring the surface position of the wafer exposure area during the stage movement, using a table or a function corresponding to the movement amount or the movement direction or the movement coordinates of the step operation in which the pitching amount generated for the measurement during the movement is obtained in advance. Since the measurement is performed after the correction driving, the positioning time can be reduced without lowering the measurement accuracy, and the throughput of the entire apparatus can be improved. Further, since there is no need to provide a special sensor or the like, there is no increase in measurement time or calculation time, the weight of the moving body, and the cost.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a positioning device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the operation of the device of FIG.

FIG. 3 is a diagram showing a flow of manufacturing a micro device.

FIG. 4 is a diagram showing a detailed flow of a wafer process in FIG. 3;

[Explanation of symbols]

1: Stage base, 2: Y linear motor, 3: Y guide, 4: Y stage, 5: X linear motor, 6: X guide, 7: X stage, 8: air pad, 9: fine movement stage, 10: Wafer, 11: light irradiation means, 13: surface position detection means, 16: control box, 18: reference table.

Claims (5)

[Claims] 1. A holding surface for holding a substrate is set to X with respect to a surface plate.
An XY table movable in each of the Y axis directions, a rotary table mounted on the XY table and capable of rotating the substrate around each of the XY axes and movable in the Z direction, and the XY table and the rotary table. In a positioning apparatus comprising a control unit for controlling driving and a surface position detecting unit for detecting a surface position of the substrate, a change amount of a surface position of the substrate caused when the XY table is moved is held in the control unit in advance. In this case, the rotation amount of the rotary table around each of the X and Y axes at the time of detection by the surface position detection means is corrected and driven independently of the rotation amount at the time of final positioning. apparatus. 2. The control device according to claim 1, wherein the change amount of the surface position is a rotation angle of a rotation direction around each axis of XY according to a movement amount and / or a movement direction of the XY table, and Z
2. The positioning according to claim 1, wherein a numerical value relating to the directional displacement is obtained in advance by calculation or measurement, and the calculated numerical value is stored as a table or a function using the moving amount and / or moving direction of the XY table as a variable. apparatus. 3. The control means obtains, as a change amount of the surface position, a correction value of a rotation angle around each of the XY axes and a correction value of a Z-direction displacement according to XY coordinates of the XY table by calculation or measurement in advance. 2. The positioning apparatus according to claim 1, wherein the information is stored as a table or a function using XY coordinates of the XY table as variables. 4. An exposure apparatus using the positioning device according to claim 1, 2 or 3. 5. A device manufacturing method, comprising manufacturing a device using the exposure apparatus according to claim 4.