JPH10321514A - Positioning device and exposure system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the increases of the rigidity and size of the main body of a positioning device by interposing a supporting means between a first base for supporting a moving means and a stool for mounting the first base and a vibration removing means between the stool and a second base which supports the stool and making the supporting reaction of the vibration removing means for supporting the stool constant. SOLUTION: A moving means 6 moves an optical system 3 for exposure and a stage 5 on which a wafer which is an object to be exposed is mounted against the optical system 3. A first base 8 supports the moving means 6 and a stool 9 supports the optical system 3 and is mounted with the first base 8. A supporting means 10 is interposed between the first base 8 and stool 9 and a vibration removing means 11 is interposed between a second base 12 supporting the stool 9 and the stool 9. In addition, a force generating means 13 is interposed between the second base 12 and stool 9 and a control means which controls the force generated from the force generating means 13 so as to make the supporting reaction of the vibration removing means 11 supporting the stool 9 always constant is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure apparatus used for semiconductor lithography, and a positioning apparatus used for various precision processing machines or various precision measuring instruments.

[0002]

2. Description of the Related Art Conventionally, a so-called stepper has been known as an exposure apparatus used for manufacturing semiconductor devices. This stepper reduces and projects a pattern image formed on an original, for example, a reticle onto a wafer by a projection lens while step-moving a substrate, for example, a semiconductor wafer under a projection lens, and sequentially places the pattern image at a plurality of positions on one wafer. Exposure. The stepper is considered to be the mainstream of the exposure apparatus in view of the performance of the resolution and the overlay accuracy.

FIG. 6 is a front view showing an example of mounting a main body structure and a wafer stage in a conventional exposure apparatus. In the figure, reference numeral 1 denotes an illumination unit that illuminates a reticle pattern;
Reference numeral 2 denotes a reticle having a pattern to be transferred, 3 denotes a projection lens that projects a pattern formed on the reticle 2 onto a wafer, and 4 denotes a lens barrel support that supports the projection lens.
5 is a top stage on which a wafer (not shown) is placed;
It has a function that can move in the θ direction, the Z direction, the α direction, and the β direction. Reference numeral 6 denotes an XY stage on which a top stage 5 is mounted and can be moved in the X and Y directions. It is a stage base supported by. Reference numeral 9 denotes a surface plate on which the stage base 8 is mounted and supported and fixed, and the lens barrel support 4 is integrally connected. Reference numeral 10 denotes a seat surface for integrally supporting and fixing the stage base 8 to the base 9. Reference numeral 11 denotes air mounts arranged at four positions to support the lens barrel support 4, and 12 denotes a base for supporting the entire apparatus via the air mount 11.
Reference numeral 33a denotes a laser interferometer for measuring a relative position between the projection lens 3 and the XY stage 6, 16a denotes a light projection unit of a focus detection unit for measuring the distance between the focal position of the projection lens 3 and the upper surface of the wafer, and 16b denotes the same. This is a light receiving unit of the focus detection unit.

[0004]

However, in such a conventional exposure apparatus, the weight of the XY stage 6 is controlled by the air mount 11 via the stage base 8, the seating surface 10, the base 9 and the lens barrel support 4. Supported. Therefore, when the XY stage 6 moves, the position of the center of gravity in the XY direction of the entire device supported by the lens barrel support 4 changes due to the weight of the stage itself, and the distribution of the support force of the plurality of air mounts 11 changes. Such a change in the support balance is X
The lens interferometer 33a for measuring the position and orientation of the Y stage 6 and the lens barrel support serving as a reference for the focus sensors 16a and 16b are changed to deteriorate the wafer overlay accuracy and the like.

In order to meet the demand for a high-speed and high-precision XY stage 6 in order to cope with an increase in the diameter of a semiconductor wafer to be mounted in the future, it is necessary to reduce the weight and improve the dynamic characteristics of the XY stage 6 and at the same time to improve the lens barrel support. It is necessary to increase the rigidity of the apparatus body such as 4th. However, strengthening the structure leads to an increase in the size and cost of the device.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the prior art, and has a positioning device capable of suppressing an increase in rigidity and size of an apparatus main body even when a stage is enlarged, and a positioning apparatus using the same. It is an object of the present invention to provide an exposure apparatus.

[0007]

In order to achieve the above object, a positioning apparatus according to the present invention comprises: a stage on which a first object (a workpiece or a workpiece) is mounted; Moving means for moving the stage for positioning with respect to a second object (measuring means or processing means, etc.), a first base supporting the moving means, and supporting the second object A surface plate on which the first base is mounted; support means interposed between the first base and the surface plate; a second base supporting the surface plate; And the second
A vibration removing means interposed between the bases, a force generating means interposed between the second base and the surface plate, and a support member of the vibration removing means for supporting the surface plate. Control means for controlling the force of the force generating means so that the force is always constant. The control unit calculates, for example, a load change in each of the fixed portions based on position coordinates before and after the movement of the stage, and controls the force generating unit to cancel the load change. Further, the first base is supported and fixed to the surface plate at three places by the support means, and the force generating means generates a force passing through substantially the center of each of the three fixed parts in the vertical direction. It is preferable to arrange them.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The positioning apparatus of the present invention is suitably used for an exposure apparatus used for semiconductor lithography. An exposure apparatus according to an embodiment of the present invention will be described with reference to FIG. 1. An exposure optical system 3 and a stage 5 on which a wafer as an object to be exposed is mounted, and the stage 5 is mounted on the exposure optical system 3 A first base 8 supporting the moving means 6 and a first base 8 supporting the exposure optical system 3;
A base 9 on which the base 8 is mounted, support means 10 interposed between the first base 8 and the base 9, a second base 12 for supporting the base 9, and the base And a force generating means 13 interposed between the second base 12 and the surface plate 9. The first base 8 is supported and fixed at three places with respect to the surface plate 9, and the force generating means 12 is arranged such that the center axis substantially coincides with the three fixed parts in the optical axis direction of the exposure optical system 3. It is arranged. Further, control means 51, 53, and 55 (see FIG. 4) for controlling the force of the force generating means 13 so that the support reaction force of the vibration removing means 11 supporting the surface plate 9 are always constant are provided. The force generating means 13 is, for example, an air cylinder or a linear motor.

[0009]

In the above configuration, the wafer stages 5, 6 are connected to X
When driven in the Y direction, the weight of the wafer stage moves,
Although the support force balance of the support means interposed between the stage base (first base) 8 and the surface plate 9 changes,
By canceling the change in the three supporting force balances by the force generating means 13 interposed between the surface plate and the second base 12, the supporting force balance of the vibration removing means 11 supporting the surface plate 9 does not change. . Therefore, high-precision positioning is performed without deforming the surface plate serving as a reference of the measuring means.

[0010]

An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a front view of an apparatus according to a first embodiment which best illustrates the features of the present invention, and FIG. 2 is a top view of a stage portion in FIG.

In FIG. 1, reference numeral 2 denotes a reticle having a pattern to be transferred, 1 denotes an illumination unit for illuminating the reticle 2, 3 denotes a projection lens for projecting a pattern formed on the reticle 2 onto a wafer, and 4 denotes a projection lens. It is a lens barrel support that supports. Reference numeral 5 denotes a top stage on which a wafer (not shown) is placed, and has a function of being movable in the θ direction, the Z direction, the α direction, and the β direction. 6 is equipped with top stage 5 and X
XY stage that can move in the direction and Y direction, 7 is XY
A movable guide that supports the stage 6 in a non-contact manner in the Y direction via a static pressure air bearing and guides the stage 6 so as to be movable in the X direction. Reference numeral 8 has a guide surface on the upper surface. A stage base 21 which is supported in a non-contact manner in the Z direction via a compressed air bearing portion, and a stage base 21 which is integrally attached to the stage base 8 supports the movable guide 7 in a non-contact manner in the X direction via a static pressure air bearing portion and Y It is a yaw guide that guides so as to be movable in the direction. Reference numeral 22 denotes a stator of a linear motor that drives the XY stage 6 in the X direction. In this linear motor, a stator is fixed to a movable guide 7, and a movable member (not shown) is attached to an XY stage 6. 23
Reference numerals a and 23b denote stators of a linear motor that drives the movable guide 7 in the Y direction, and are disposed and fixed to the stage base 8 so as to face each other. 24a and 24b
Is a mover of a linear motor that drives the movable guide 7 in the Y direction, and is attached to the movable guide 7 so as to face each other. 9 is a surface plate on which a stage base 8 is mounted,
Reference numeral 10 denotes a seat surface for integrally supporting and fixing the stage base 8 to the base 9. The seating surfaces 10 are arranged at three places between the stage base 8 and the surface plate 9 as described later. The surface plate 9 and the lens barrel support 4 are integrally connected. Numeral 11 denotes air mounts arranged at four positions for supporting the lens barrel support 4, and numeral 12 denotes a base for supporting the entire apparatus via the air mount 11. The air mount 11 is mounted on the base 1
Vibration transmitted from the lens 2 to the lens barrel support 4 and the base 9 is insulated. Reference numeral 13 denotes an air cylinder disposed just below the seating surface 10 (in the Z-axis direction) and fixed to the base 12 to apply a force in the Z-direction to the base 9. The air cylinder 13 has little rigidity and does not transmit vibration of the base 12 to the surface plate 9.

Reference numeral 33a denotes a laser interferometer for measuring a relative position between the projection lens 3 and the XY stage 6, 16a denotes a light projection unit of a focus detection unit for measuring a distance between the focal position of the projection lens 3 and the upper surface of the wafer, Reference numeral 16b is a light receiving unit of the focus detection unit. The light projecting unit 16a and the light receiving unit 16b are each fixed to the projection lens 3.

FIG. 3 is a perspective view showing the arrangement of a measuring system (laser measuring system) for the XY stage of the exposure apparatus according to the present embodiment, and shows a portion such as a laser interferometer 33a around the top stage 5 in FIG. It is the figure represented in detail.

In FIG. 1, reference numeral 31 denotes a laser head as a light source; 32a and 32b, reflection mirrors mounted on the top stage 5 in FIG. 1; 33a, an interferometer for measuring the X direction; Reference numeral 33c denotes an interferometer for measuring the yawing of the top stage 5, that is, the θ direction with respect to the optical axis of the projection lens. 34a, 34
b and 34c are receivers for converting interference fringes into electric signals, 34a is for the X direction, 34b is for the Y direction, and 34c is θ.
For directions.

FIG. 4 is a system diagram of a control system according to this embodiment. In the figure, reference numeral 51 denotes the X, Y, θ laser measurement system shown in FIG. 3, which measures the position of the XY stage 6 on which the top stage 5 is mounted. Reference numeral 53 denotes a controller that feeds back position signals of the XY stage 6 and the top stage 5 and issues a predetermined operation command to each drive shaft. Reference numeral 56 denotes a driver for driving the XY stage 6 by passing a current through the coil portions of the linear motor stators 22 and 23a and 23b in FIG.
Reference numeral 55 denotes a driver for driving the air cylinder 13 in FIG. 1 in response to a command from the controller 53, and reference numeral 57 denotes a driver for driving each drive shaft of the top stage 5.

In the above configuration, first, a wafer (not shown) to be exposed is placed on the top stage 5, and a drive signal is given from the controller 53 to the XY stage 6 and the top stage 5, and the wafer is moved to a predetermined position under the projection lens 3. Is driven to the position and posture. Here, the X direction, the Y direction, the Z direction, and the rotation direction of each axis (α
The deviation of the target position (direction, β direction, θ direction) from the target position is calculated by the controller 53 based on the outputs of the laser measurement system and the focus detection system, and is fed back to each drive unit, so that the wafer has a predetermined position and posture. Is controlled. After the exposure, the operation of moving to the next predetermined position and exposing is repeated.

The XY stage 6 is moved by receiving a command signal from the controller 53 to the linear motor driver 56 so as to follow a predetermined speed curve, and causing the linear motor to generate a driving force according to the command signal. .
When the XY stage 6 moves in the XY directions within the stroke range and the positions of the XY stage 6, the top stage 5 and the movable guide 7 change, the balance of the weight supported by the stage base 8 changes, and The distribution of the supporting load changes. At this time, a command signal is given from the controller 53 to the air cylinder driver 55 so that a force in the opposite direction (Z direction) according to the change in the supporting load is given from the air cylinder 13 to the base 9.

FIG. 5 is a top view of the arrangement of the cylinders of this embodiment. In the figure, 10 (10a, 10b, 10
c) is each seat surface supporting the stage base 6.
13 (13a, 13b, 13c) is just below the seating surface (Z
Direction), and each air cylinder that applies a force to the platen 9.

R ₁ , R ₂ , R ₃ represent the additional load applied to the platen 9 by the air cylinder 13, and L ₁ , L ₂ represent the distance between the support points. G is the center of gravity of the entire stage movable portion such as the XY stage 6, the top stage 5, and the movable guide 7, and the position of the stage center of gravity at an arbitrary position is represented by coordinates (x, y). In such a configuration,
The weight of the entire stage movable part is W, and this is the additional load R
When balanced with _1, R _2, R _3, each additional load represented by the equation (1).

[0020]

(Equation 1) Here, the position of the center of gravity G of the stage movable portion (x, y) is (x _a, y _a) from (x _b, y _b) When vary within the scope of, the seating surface 10a, 10b, 10c support the load of Change Δ
R ₁ , ΔR ₂ , ΔR ₃ are the additional loads R ₁ , R ₂ , R ₃
Is the difference between the maximum value and the minimum value, and is expressed by equation (2).

[0021]

(Equation 2) ΔR _1, ΔR _2, the largest value among the [Delta] R ₃ and W _R, when this load is balanced with the additional load _{R 1, R 2, R 3} , (1) formula is expressed as (3) You.

[0022]

(Equation 3) Therefore, the additional loads R ₁ , R ₂ and R ₃ can be easily obtained by calculating the position of the center of gravity of the stage movable portion from the position command signal of the stage and applying the calculated position to the equation (3).

The feature of this embodiment is that the XY stage 6
Is driven in the X and Y directions, the weight of the stage movable part moves, and the support force balance of three seat surfaces 10 interposed between the stage base 6 and the surface plate 9 changes.
The change in the supporting force balance is canceled by three air cylinders 13 interposed between the base 9 and the base 12 in the vicinity immediately below. Therefore, the support force balance of the air mount 11 supporting the entire apparatus does not change, and the lens barrel support 4 serving as a reference of the measurement unit does not deform. For example, a change in the distance between the projection lens 3 and the interferometer 33a is not affected. And highly accurate positioning with high reproducibility is performed.

In this embodiment, the additional load of the air cylinder 13 is calculated by the position of the stage.
A means for detecting the support force of the air mount 11 is provided, and the additional loads R ₁ , R ₂ , and R ₃ of the air cylinder 13 are feedback-controlled based on the force signals so as to suppress the deformation of the lens barrel support 4. Is also good.

The air cylinder 13 is used as a force generating means.
Is interposed between the surface plate 9 and the base 12 immediately below the seating surface 10, but the same effect can be obtained even if this is a linear motor.

As described above, according to the exposure apparatus of the present invention,
When the wafer stage is driven in the X and Y directions, the weight of the wafer stage moves, and the support force balance of three seats interposed between the stage base (first base) and the surface plate changes. Vibration removing means for supporting the lens barrel support and the surface plate (apparatus main body structure) by canceling changes in the three supporting force balances by force generating means interposed between the surface plate and the second base. The support force balance does not change. Therefore, high-precision positioning is performed without deformation of the surface plate and the lens barrel support serving as references for the measuring means.

Further, since the deformation of the apparatus main body (the lens barrel support and the surface plate) due to the stage movement can be suppressed,
Even if the size of the wafer stage is increased with the increase in the size of the wafer, the rigidity of the apparatus main body and the cost increase due to the increase in size can be suppressed.

[0028]

Next, an embodiment of a device production method using the above-described exposure apparatus will be described.
FIG. 7 shows a micro device (a semiconductor chip such as an IC or an LSI,
2 shows a flow of manufacturing a liquid crystal panel, a CCD, a thin-film magnetic head, a micromachine, and the like. In step 1 (circuit design), a device pattern is designed. Step 2 is a process for making a mask on the basis of the designed pattern. On the other hand, in step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon or glass. Step 4
The (wafer process) is called a pre-process, and 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. Step 6
In (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. 8 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. In this embodiment, in each of the repeated processes,
By performing stable and highly accurate positioning, accurate exposure can be performed without being affected by the process.

The use of the exposure apparatus of this embodiment makes it possible to manufacture a highly integrated device, which was conventionally difficult to manufacture, at low cost.

[0031]

According to the present invention, when the stage is driven, the weight of the stage moves, and the support force balance of three seats interposed between the first base and the surface plate changes. But
The force generation means interposed between the surface plate and the second base cancels out changes in the support force balance at three places, thereby achieving the second
The support force balance of the vibration removing means supporting the object and the surface plate does not change. Therefore, high-accuracy positioning is performed without deformation of the surface plate or the second object serving as a reference for measurement and processing.

Further, the apparatus main body (second
Object and surface plate) can be suppressed,
Even if the stage is increased in size as the size of the first object is increased, the rigidity of the apparatus main body can be suppressed, and the cost increase due to the increase in size can be suppressed.

[Brief description of the drawings]

FIG. 1 is a front view of an exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a top view showing a stage portion of the apparatus of FIG.

FIG. 3 is a perspective view showing an arrangement of a laser measurement system of the apparatus shown in FIG. 1;

FIG. 4 is a system configuration diagram of a control system of the apparatus in FIG. 1;

FIG. 5 is a top view showing an arrangement of a cylinder portion of the apparatus of FIG. 1;

FIG. 6 is a front view showing a conventional exposure apparatus.

FIG. 7 is a diagram showing a flow of manufacturing a micro device.

FIG. 8 is a diagram showing a detailed flow of a wafer process in FIG. 7;

[Explanation of symbols]

1: illumination part, 2: reticle, 3: projection lens (second object), 4: lens barrel support, 5: top stage, 6: XY
Stage (moving means), 7: movable guide, 8: stage base (first base), 9: surface plate, 10, 10a, 10
b, 10c: seating surface (supporting means), 11: air mount (vibration removing means), 12: base (second base), 13,
13a, 13b, 13c: air cylinders (force generating means).

Claims (10)

[Claims] 1. A stage on which a first object is mounted, moving means for moving the stage to position the first object with respect to a second object, and a first means for supporting the moving means. A base, a base plate supporting the second object and mounting the first base, support means interposed between the first base and the base, and the base A second base supporting the base, vibration removing means interposed between the base and the second base, and a force generator interposed between the second base and the base. And a control means for controlling the force of the force generating means so that the support reaction force of the vibration removing means for supporting the surface plate is always constant. 2. The control means calculates a load variation in each of the fixed portions based on position coordinates before and after movement of the stage, and controls the force generating means to cancel the load variation. The positioning device according to claim 1, wherein: 3. The support means supports and fixes the first base at three places with respect to the surface plate, and the force generating means applies a force passing through substantially the center of each of the three fixed parts in the vertical direction. 3. An arrangement as claimed in claim 1, wherein:
The positioning device according to the above. 4. The positioning device according to claim 3, wherein said force generating means is three air cylinders each having a central axis substantially aligned with each of said vertical axes. 5. The positioning device according to claim 3, wherein said force generating means is three linear motors each having a central axis substantially aligned with each of said vertical axes. 6. An exposure optical system, a stage on which an object to be exposed is mounted, moving means for moving the stage with respect to the exposure optical system, and a first base supporting the moving means. A surface plate for supporting the exposure optical system and mounting a first base, a support means interposed between the first base and the surface plate, and a second substrate for supporting the surface plate A base, a vibration removing unit interposed between the base and the second base, and a force generating unit interposed between the second base and the base. Supports and fixes the first base at three places with respect to the base plate, and the force generating means is arranged so that the center axis substantially coincides with the fixed part at the three places in the optical axis direction of the exposure optical system. An exposure apparatus, wherein the exposure apparatus is disposed. 7. A control means for controlling a force of said force generating means so that a support reaction force of said vibration removing means for supporting said surface plate is always kept constant.
Exposure apparatus according to the above. 8. An exposure apparatus according to claim 6, wherein said force generating means is an air cylinder. 9. An exposure apparatus according to claim 6, wherein said force generating means is a linear motor. 10. A semiconductor device manufactured using the exposure apparatus according to claim 6. Description: