JPH11330210A - Stage equipment, aligner and device manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately eliminate stage position measuring errors which are to be caused by elastic deformation due to a stage driving force and easily increase precision of the stage, by correcting a position measuring value of a stage by using a correcting vector where the measured result of a sensor is multiplied by a constant coefficient matrix. SOLUTION: Moving is performed as far as a position where a mark 6 written on a wafer 7 can be measured with a TTL-off-axis scope. Actuators of the respective axes, i.e., an X axis linear motor, a Y axis linear motor, a θz axis actuator 14, and a Z tilt axis are vibrated every one axis. Driving current values of the respective axes, measured values of the X axis and the Y axis of the TTL-off-axis scope, X axis laser interferometer deviation, and θz axis laser interferometer deviation are measured. Proportionality factor matrix is obtained from the above values. By using a correcting vector where the matrix is multiplied by the measured value of a sensor, measuring errors of the laser interferometers of the respective axes of a wafer stage which are to be caused by elastic deformation due to a stage driving force can be corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-speed and high-precision positioning stage device, and is suitably applied to, for example, a reticle moving stage device or a wafer moving stage of a semiconductor exposure apparatus. Further, the present invention relates to an exposure apparatus having the positioning stage device, and a device manufacturing method for manufacturing a device using the exposure apparatus.

[0002]

2. Description of the Related Art Conventionally, a positioning stage device used in a semiconductor exposure apparatus mounts a position control target such as a wafer or a reticle and requires high positioning accuracy. Stage position measuring means combining a gauge and a laser mirror has been widely used.

However, since the position control target point and the position measurement target point do not coincide with each other, there has been a problem that a deformation due to a temperature change or a stress change therebetween causes a position measurement error.

[0004]

SUMMARY OF THE INVENTION On the other hand, Japanese Unexamined Patent Application Publication No.
In Japanese Patent Application Laid-Open No. 291910, as shown in FIG. 8, an electric micrometer 106 measures a distance variation between a laser mirror 101 as a position measurement target and a wafer 102 as a position control target.
And a method of correcting a distance variation between the position control target point and the position measurement target point by adding the measured value to the positioning laser target value is proposed.

However, even in this method, the fixing jig 10 for fixing the electric micrometer 106 to the top table 104 is used.
There is a problem that the measurement error due to the deformation or inclination of the fifth embodiment cannot be corrected. In other words, as long as an additional length measurement sensor is used, the measurement error cannot be completely corrected in the end, so it is necessary to accurately correct the distance fluctuation between the position control target point and the position measurement point without using the additional length measurement sensor. there were.

[0006] Of these, measurement errors due to temperature changes can be prevented by using a low thermal expansion material or a temperature control device, but increasing the speed of the stage for the purpose of shortening the moving time increases measurement errors due to elastic deformation. Therefore, the need to correct the fluctuation of the distance due to the elastic deformation of the stage in particular has increased.

[0007]

In order to solve the above-mentioned problems, a stage apparatus according to the present invention is provided with a stage for mounting and moving an object, stage position measuring means for measuring the position of the stage, and acting on the stage. A sensor for measuring a fluctuation amount of a main force or a physical amount proportional to the main force, and a means for correcting a position measurement value of the stage by a correction vector obtained by multiplying a measurement result of the sensor by a constant coefficient matrix. I do. Here, the stage position measuring means may have a laser interferometer and its reflection mirror.

[0008] In addition, usually, there is provided a separate position measuring means provided in addition to the stage position measuring means, and the constant coefficient matrix is used to determine the amount of change in the stage driving force of each axis when the stage is moved, or Is obtained by a regression analysis of a physical quantity proportional to, and a difference value measured by the separate measuring means and the position measuring means. The sensor may be any one of a means for monitoring a current value of a motor for driving the stage, and a load cell or a strain gauge installed at a portion receiving a driving reaction force of the motor.

Further, the present invention is characterized in that the stage apparatus has a means for exposing a wafer or a reticle mounted on the stage apparatus, and a device is manufactured using the exposure apparatus. Device manufacturing method.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a main force acting on a stage by a sensor or a physical quantity proportional thereto, for example, a monitor value of a current value of a motor for driving a stage,
Measure any of the measured values of the load cell or strain gauge installed in the part receiving the motor's driving reaction force, and multiply the measured value of this sensor by the appropriate coefficient matrix to obtain the position control target point and the vector. The method is characterized in that a distance variation from a position measurement target point is predicted and corrected. At this time, since a method of accurately estimating an appropriate coefficient matrix is important, a method of estimating the coefficient matrix will be described in detail.

In the present invention, a command signal is provided so that the stage driving force has a white noise or sine wave sweep waveform, and the stage driving force fluctuation or a physical quantity proportional thereto and a stage position measuring instrument, and further another evaluation position Measure the position at the same time with the measuring instrument.

Since a semiconductor exposure apparatus has an alignment measuring device for measuring the position of a wafer with reference to an exposure optical axis, it is convenient to use an alignment measuring device as an evaluation position measuring device.

In this case, the measurement value vector of the position measuring meter for evaluation is expressed by the following equation (1). Dx + dx = Dx ₀ + dx ₀ + A (F _e + f _e ) + dx _e (1) where, Dx: a column vector indicating the average of the values of the evaluation position meter dx: a column indicating the fluctuation of the value of the evaluation position meter Vector Dx ₀ : Column vector indicating the difference between the value of the stage position measuring instrument and the command value, that is, the average value of the position deviation dx ₀ : Column vector indicating the variation of the position deviation A: Coefficient matrix F _e : Stage driving force or mean value of the column base vector indicating a physical quantity which is proportional to f _e: variation in the column base vector indicating the physical quantity that is proportional stage driving force or to dx _e: other errors

Next, when the constant terms are removed from both sides of the equation (1), the equation (2) is obtained. _{dx = dx 0 + Af e +} dx e (2) In this case, the estimated value A of the coefficient matrix is determined as the sum of the squares of the correction residual dx _e is minimized.

Specifically, it can be obtained by the following equation (3) using a pseudo inverse matrix. A = (dx−dx ₀ ) ^* pinv ( _fe ) (3) where pinv ( ^* ): indicates a pseudo-inverse matrix

The stage position caused by the elastic deformation of the stage is obtained by the correction matrix obtained by multiplying the coefficient matrix A thus obtained by the stage driving force constantly measured by the sensor or the column vector indicating the physical quantity proportional to the driving force. Errors in the measured values can be removed.

Note that if there is a time difference between the timing of the stage driving force measured by the sensor or the physical quantity proportional thereto and the timing of the stage position measurement, the correction will be inaccurate. Therefore, it is preferable to perform both measurements simultaneously.

As described above, there is a distance between a position measurement target point to be measured originally and a position measurement target point actually measured, and the positioning stage is changed by the elastic deformation due to the stage driving force. In, at least a measurement error due to the stage driving force is corrected.

In this case, correction may not be possible in a high-frequency region where the natural vibration of the stage is excited. However, even when the natural frequency of the movable stage is sufficiently high, or even when the natural frequency of the movable stage is low, the stage cannot be corrected. In the state in which the driving force is not applied and the high-frequency vibration is attenuated, that is, in the state where the stage is stationary or moving at a constant speed, the high-frequency component of the measurement error due to the stage deformation becomes small, so in practice It doesn't matter.

In the present embodiment, since the error component can be predicted, the throughput can be improved while maintaining the overlay accuracy. Furthermore, by using this means, the performance required for the structure is emphasized on the viewpoint of good reproducibility rather than the viewpoint of high rigidity, and the weight of the stage structure is increased more than necessary. Can be prevented.

Since the present invention can be implemented only by installing a sensor for measuring the driving force of the stage or a physical quantity proportional thereto and improving the measurement control software, a significant design change is not required and the implementation is simple. .

[0022]

EXAMPLES Specific examples will be described below.

The first embodiment shown in FIG. 1, FIG. 2 and FIG.
This is an example in which a correction coefficient is estimated by applying the present invention to a wafer stage of a projection exposure apparatus and using an alignment TTL-off-axis scope as an evaluation position measuring instrument.

In FIG. 1, 1 is a projection lens, 2 is a main body structure, 3 is a laser interferometer for a wafer stage, and 4 is a TT
L-off-axis scope, 5 is a wafer stage, and 6 is a TTL-off-axis scope mark. Further, as described above, a sensor (not shown) for measuring the force acting on the stage or a physical quantity proportional to the force is provided. FIGS. 2 and 3 show the wafer stage 5 in FIG.

In FIG. 2, 7 is a wafer, 8 is an X-axis laser interferometer mirror, 9 is a Y-axis laser interferometer mirror,
0 is a wafer stage top plate, 18 is an X-axis slider, 19 is a Y-axis slider, 20 is a Y-axis drive linear motor movable element, 2
Reference numeral 1 denotes a Y-axis drive linear motor stator, and reference numeral 22 denotes a wafer stage base.

In FIG. 3, 11 is a Z tilt actuator, 12 is a θz stage, 13 is a leaf spring guide, 14
Is the θz actuator, 15 is the XY stage, 16 is the X
The axis drive linear motor mover 17 is an X axis drive linear motor stator.

In such an embodiment, first, the coefficient matrix A
The estimation will be described. First, the mark 6 written on the wafer 7 is moved to a position where it can be measured by the TTL-off-axis scope. From this state, the actuators of each axis, that is, the X-axis linear motor, the Y-axis linear motor, the θz-axis actuator, and the tilt axis are vibrated one by one, and the drive current value of each axis and the X-axis and Y-axis of the TTL-off-axis scope Axis measurement value, deviation of X-axis laser interferometer 3,
A Y-axis laser interferometer deviation (not shown) and a θz-axis laser interferometer deviation (not shown) are measured.

When these values are applied to the equation (3), a proportionality constant matrix A is obtained. When a correction vector obtained by multiplying the proportionality constant matrix A by a sensor measurement value is used, each wafer stage caused by elastic deformation due to the stage driving force is used. The measurement error of the axial laser interferometer can be corrected. Since the coefficient matrix changes depending on the wafer shot position, a coefficient matrix obtained at a representative shot position is used by performing interpolation approximation according to the shot position.

In the second embodiment shown in FIG. 4, 23 off-axis scopes without a projection lens are used in place of the TTL-off-axis scope in the first embodiment. In this case, the correction of the laser interferometer is 24
Is used when measuring global alignment using the off-axis scope mark.

The third embodiment shown in FIG. 5 is an example applied to a reticle stage of a scanning projection exposure apparatus. In FIG. 5, reference numeral 25 denotes a laser interferometer for a reticle stage;
Is a laser interferometer mirror, 27 is a mark for a reticle alignment scope, 28 is a reticle alignment scope, 29 is a reticle, 30 is a linear motor stator, 31
Is a linear motor mover, 32 is a reticle stage, 33
Is an illumination system. Further, as described above, a sensor (not shown) for measuring the force acting on the stage or a physical quantity proportional to the force is provided.

In such an embodiment, first, the coefficient matrix A
The estimation will be described. First, reticle alignment scope mark 27 written on reticle 29
Move the reticle alignment scope 28 to a position where it can be measured. From this state, the actuator of each axis, that is, the Y-axis linear motor is vibrated, and the drive current value and the deviation of the Y-axis laser interferometer of the reticle alignment scope are measured.

When these values are applied to equation (3), a proportionality constant matrix A is obtained. If a correction vector obtained by multiplying the matrix by a sensor measurement value is used, a reticle caused by elastic deformation due to a stage driving force is used. The measurement error of the stage Y-axis laser interferometer can be corrected.

(Embodiment of Device Production Method) 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, micromachines, etc.). 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. 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. 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 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. 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 manufacture a highly integrated device, which was conventionally difficult to manufacture, at low cost.

[0035]

According to the present invention, it is possible to accurately remove a stage position measurement error caused by an elastic deformation due to a stage driving force without adding a distance sensor as in the prior art, so that the stage can be easily adjusted. Accuracy can be improved.

Further, even if the stage driving force increases due to the speeding up of the stage, it is not necessary to increase the rigidity of the stage structure, so that it is possible to achieve both high precision and high speed of the stage at a high level. is there.

[Brief description of the drawings]

FIG. 1 is a diagram of a semiconductor exposure apparatus according to a first embodiment.

FIG. 2 is a front view of a stage of the semiconductor exposure apparatus according to the first embodiment.

FIG. 3 is a sectional view of a stage of the semiconductor exposure apparatus according to the first embodiment.

FIG. 4 is a view of a semiconductor exposure apparatus according to a second embodiment.

FIG. 5 is a view of a semiconductor exposure apparatus according to a third embodiment.

FIG. 6 is a flowchart of manufacturing a micro device.

FIG. 7 is a detailed flowchart of a wafer process.

FIG. 8 is an example of the prior art.

[Explanation of symbols]

1: Projection lens, 2: Main body structure, 3: Laser interferometer for wafer stage, 4: TTL-off-axis scope,
5: wafer stage, 6: TTL-off-axis scope mark, 7: wafer, 8: X-axis laser interferometer mirror, 9: Y-axis laser interferometer mirror, 10: wafer stage top plate, 11: tilt Actuator, 12: θz
Stage, 13: leaf spring guide, 14: θz actuator, 15: XY stage, 16: X-axis drive linear motor mover, 17: X-axis drive linear motor stator, 18:
X-axis slider, 19: Y-axis slider, 20: Y-axis drive linear motor mover, 21: Y-axis drive linear motor stator, 22: Wafer stage base, 23: Off-axis scope, 24: Off-axis scope mark , 25:
Laser interferometer for reticle stage, 26: laser interferometer mirror, 27: reticle alignment scope mark, 28: reticle alignment scope, 29: reticle, 30: Y-axis linear motor stator, 31: Y-axis linear motor mover, 32: reticle stage, 33: illumination system, 101: laser interferometer mirror, 102: wafer, 1
03: wafer holding and rotating mechanism, 104: top table,
105: fixing jig, 106: electric micrometer.

Claims (6)

[Claims] A stage for mounting and moving an object;
Stage position measuring means for measuring the position of the stage,
A sensor for measuring a fluctuation amount of a main force acting on the stage or a physical amount proportional thereto, and a means for correcting a position measurement value of the stage by a correction vector obtained by multiplying a measurement result of the sensor by a constant coefficient matrix. A stage device comprising: 2. The stage apparatus according to claim 1, wherein the stage position measuring means has a laser interferometer and a reflection mirror thereof. 3. The apparatus according to claim 1, further comprising: a position measuring unit provided in addition to the stage position measuring unit, wherein the constant coefficient matrix is a change amount of a stage driving force of each axis when the stage is moved or proportional to the fluctuation amount. The measured physical quantity, the separate measuring means,
2. The stage device according to claim 1, wherein the stage device is obtained by regression analysis of a difference value measured by the position measuring means. 4. The sensor according to claim 1, wherein the sensor is any one of a means for monitoring a current value of a motor for driving the stage, and a load cell or a strain gauge installed at a portion receiving a driving reaction force of the motor. 2. The stage device according to 1. 5. The stage device according to claim 1,
An exposure apparatus comprising: means for exposing a wafer or a reticle mounted thereon. 6. A device manufacturing method, comprising manufacturing a device using the exposure apparatus according to claim 5.