JP2000068195A - Device manufacturing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the device manufacturing accuracy and throughput by changing characteristics of an active damper such as a damping factor and an integral gain according to the rigidity of the installation floor. SOLUTION: In an active damper of a device manufacturing equipment, the output of an acceleration sensor 22 for measuring the acceleration in the direction vertical to the floor 100 is inputted to a floor rigidity estimating circuit 24 through a low pass filter 23 for eliminating an offset and high-frequency noise. The floor rigidity estimating circuit 24 is also inputted with the information (stg) on the movement of an XY stage for exposure. Then, the floor rigidity estimating circuit 24 calculates the excitation force to be transmitted to the floor 100 from the information (stg) on the movement of the XY stage. From the calculated excitation force and the floor vibration obtained from the second acceleration sensor 22, the floor rigidity estimating circuit 24 calculates the rigidity of the floor to set the optimum values for a proportional gain and an integral gain of a PI compensatory 10'. The proportional gain works as a damping factor of a damper stage and the integral gain works like a spring factor of the damper stage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device manufacturing apparatus for manufacturing a device such as a semiconductor device or a liquid crystal device, and more particularly to a characteristic of an active damper for supporting a movable portion such as an XY stage on an installation floor in the device manufacturing apparatus. The present invention relates to a device manufacturing apparatus capable of maximizing the anti-vibration and vibration-damping performance of an active damper by adjusting the height according to the rigidity of the installation floor.

[0002]

2. Description of the Related Art A precision equipment group which dislikes vibration is mounted on a vibration isolation table of a vibration isolation device. For example, an XY stage for exposure such as an optical microscope and a stepper is used. In particular, in the case of an exposure XY stage, the stage must be mounted on a vibration isolation table that minimizes vibration transmitted from the outside in order to perform appropriate and rapid exposure. This is because exposure must be performed with the exposure XY stage completely stopped. Further, it must be noted that the XY stage has an intermittent operation called step-and-repeat as an operation mode, and generates repetitive step vibrations, which causes vibrations of the vibration isolation table. Even when such vibrations remain, it is impossible to start the exposure operation. Therefore, it is required for the vibration damping device to achieve a good balance between vibration damping against external vibration and vibration damping performance against forced vibration caused by the motion of the mounted device itself.

[0003] Instead of a step-and-repeat type semiconductor exposure apparatus in which the XY stage is completely stopped and then the silicon wafer mounted on the stage is irradiated with exposure light, the exposure light is scanned while scanning the XY stage. A scan type semiconductor exposure apparatus that irradiates a silicon wafer with light has also appeared. It is also necessary for vibration damping devices used in such devices to have a good balance between vibration damping against external vibration and vibration suppression performance against forced vibration caused by the motion of the equipment mounted on the vibration damping device itself. It is the same.

[0004] As is well known, the form of realization of a vibration isolator is classified into a passive vibration isolator and an active vibration isolator (active damper). In recent years, there has been a tendency to use active vibration isolators in order to meet the demands for high-accuracy positioning, high-accuracy scanning, high-speed movement, etc., which are required for devices mounted on the vibration isolators. As an actuator used in an active vibration isolator, a force generating actuator such as an air spring or a voice coil motor, and a displacement generating actuator such as a piezoelectric element are known.

First, the configuration and operation of an active vibration isolator using an air spring as an actuator will be described with reference to FIG. In the figure, 1 is a servo valve for supplying and exhausting air of a working fluid to and from an air spring 2, 3 is a position sensor for measuring (vertical) displacement of a vibration isolation table 4, 5 is a mechanical spring for preload,
Reference numeral 6 denotes a viscous element expressing the viscosity of the air spring 2, the preload mechanical spring 5, and the entire mechanism (not shown). The mechanism combined from these components is called the pneumatic spring support leg 16. Next, the configuration and operation of the feedback device 7 for the air spring type support leg 16 will be described. First, an acceleration sensor 8 for measuring the (vertical) acceleration of the vibration isolation table 4
Is negatively fed back to the previous stage of the voltage / current converter 11 for opening and closing the valve of the servo valve 1 via a DC cut low-pass filter 9 and a P compensator 10 for removing offset and high frequency noise. Damping is provided to the mechanism by this acceleration feedback loop to achieve stabilization. Here, P means a proportional operation.

Further, the output of the position sensor 3 passes through a displacement amplifier 12 and is input to a comparison circuit 13. Here, a deviation signal e is obtained by comparison with a target voltage 14 equivalent to a target position with respect to the ground (installed floor) with which the air spring type support leg 16 contacts. The deviation signal e excites the voltage-current converter 11 through the PI compensator 15. Then, the pressure in the air spring 2 is adjusted by opening and closing the servo valve 1, so that the vibration isolation table 4 can be maintained at a desired position specified by the target voltage 14 without a steady deviation. Here, P means a proportional operation and I means an integral operation.

As shown in FIG. 3, in an active vibration isolator using an air spring as an actuator, a position feedback loop and an acceleration feedback loop are combined to provide feedback for positioning control and vibration control of the vibration isolation table 4. The device 7 is constituted. In order to configure these feedback loops, the position sensor 3 and the acceleration sensor 8 are used as physical information detection sensors. Position sensor 3
For example, an eddy current type position sensor is known, and as the acceleration sensor 8, a servo type acceleration sensor is known.

Next, the configuration and operation of an active vibration isolator using a voice coil motor (hereinafter abbreviated as VCM) comprising a permanent magnet and a winding coil as an actuator will be described with reference to FIG. The output signal of the acceleration sensor is passed through an integrator to be converted into a speed signal, and this signal is used to excite a power amplifier that drives a VCM, and as a result, is applied to a vibration isolation table 4 that supports only damping. Configuration. In the figure, reference numeral 17 denotes an integrator for converting the output signal of the acceleration sensor 8 passed through the DC cut low-pass filter 9 into a velocity dimension, and 19 denotes V
A power converter for driving the CM 20 and 21 are VCM type support legs. Note that the integrator 17 may be a pseudo-integrator as needed. An active vibration isolator using a VCM as an actuator is characterized by quick response. However, in order to support the positioning of a heavy object, a constant current must be supplied to the winding coil to cause a heat generation problem, which is disadvantageous. A control loop is configured to drive the VCM only in response to the vibration.

[0009]

In the conventional active vibration isolator, the damping coefficient can be set to an optimum value by adjusting the proportional gain of the P compensator 10. However, the floor on which the semiconductor exposure apparatus is installed, that is, the floor of a semiconductor factory is often the upper layer of a building, and therefore, the floor rigidity of the semiconductor exposure apparatus is often insufficient. Also,
The floor stiffness of each semiconductor exposure device differs depending on the positional relationship between each installation location of the semiconductor exposure device and the pillars and beams of the building.
Further, when only the installation area of the semiconductor exposure apparatus is viewed, the floor stiffness is not uniform, and the vibration state is different for each step-and-repeat or step-and-scan due to the difference in the floor stiffness in each axial direction. Variations in positioning time and accuracy occurred.

[0010] In this case, the damping coefficient and the spring constant set at the time of shipment of the device cannot maximize the vibration isolation performance and the vibration suppression performance 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 provides an active damper for supporting at least a part of a device manufacturing apparatus such as a semiconductor exposure apparatus. The purpose is to maximize the performance regardless of the rigidity of the floor.

[0012]

To achieve the above object, according to the present invention, in a device manufacturing apparatus in which at least a movable portion is supported on an installation floor via an active damper, means for measuring the rigidity of the installation floor is provided. Means for changing the characteristics of the active damper according to the measurement. As the characteristics of the active damper,
For example, the spring constant and the damping coefficient are changed. Also,
The rigidity of the installation floor is estimated by measuring the vibration of the installation floor using a vibration sensor such as an acceleration sensor, and based on the measurement result and the driving information of the movable section.

[0013]

In the above conventional example, there is no means for measuring the floor stiffness of the floor on which the device manufacturing apparatus is installed. Therefore, it is difficult to adjust the active damper to optimal characteristics, for example, a spring constant and a damping coefficient. According to the present invention, the rigidity of the installation floor is measured, and the characteristic of the active damper is changed according to the measured rigidity. Therefore, the characteristic of the active damper can be optimally adjusted for the rigid floor. Thus, the active damper can exhibit its anti-vibration performance and vibration-damping performance to the maximum according to the rigidity of the installation floor.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In one embodiment of the present invention,
The device manufacturing apparatus is a semiconductor exposure apparatus, wherein the active damper includes a vibration isolation table on which an exposure XY stage is mounted, elastic support means for elastically supporting the vibration isolation table, and an actuator for driving the vibration isolation table. A first acceleration sensor for detecting vibration of the vibration isolation table, a vibration control compensator for feeding back an output of the first acceleration sensor, a displacement sensor for detecting displacement of the vibration isolation table, and an output of the displacement sensor. Position control compensating means for feeding back, at least one second acceleration sensor for detecting vibration of the installation floor,
A floor stiffness estimating circuit for estimating the floor stiffness of the floor of the vibration isolation table by inputting the output of the acceleration sensor and the movement information of the exposure XY stage, and a feedback loop of the first acceleration sensor installed on the vibration isolation table. A floor compensator capable of changing a proportional gain and an integral gain; measuring a floor vibration generated when the exposure XY stage is moved by the second acceleration sensor; Is estimated, and the spring constant and the damping coefficient of the active vibration isolator are adjusted to optimal values by changing the proportional gain and the integral gain of the PI compensator to optimal values. As the actuator, one or both of an air spring and a voice coil motor can be used.

In the above arrangement, the second acceleration sensor measures the floor vibration of the floor on which the semiconductor exposure apparatus is installed, and the floor stiffness estimating circuit calculates the exciting force transmitted to the floor from the movement information of the exposure XY stage. The floor stiffness is estimated by calculation or learning from the calculated vibration force and the floor vibration obtained from the second acceleration sensor, and the proportional gain and the integral gain of the PI compensator are set to optimal values. It has the function of re-executing.
The proportional gain acts as a damping coefficient of the vibration damping table, and the integral gain operates like a spring coefficient of the vibration damping table.

[0016]

FIG. 1 is a diagram showing a configuration of an active vibration isolator (active damper) according to one embodiment of the present invention. The anti-vibration apparatus of FIG. 1 is for mounting an exposure XY stage of a semiconductor exposure apparatus. In FIG. 1, portions denoted by the same reference numerals as those in FIG. 3 are configured in the same manner as those in FIG.

If the floor stiffness of the floor 100 on which the apparatus is installed is not sufficient, a load change of each support leg generated in the vertical direction when the XY stage (not shown) moves, and a reaction force of acceleration / deceleration of the stage movement. The floor 100 vibrates due to the reaction force generated in the horizontal and rotational directions. Therefore, the vibration isolator needs to further drive the actuator in order to generate a force that cancels the floor vibration generated due to the movement of the XY stage. The active vibration damping device of the present embodiment enables this function.

1 is different from the apparatus shown in FIG. 3 in that a P compensator 10 is provided on a first
That the proportional gain and the integral gain of the feedback loop of the acceleration sensor 8 can be changed to a PI compensator 10 ′ that can be changed, the second acceleration sensor 22 installed on the floor 100, the DC cut low-pass filter 23, That is, the rigidity estimation circuit 24 is added.

In FIG. 1, the output of the acceleration sensor 22 for measuring the (vertical) acceleration of the floor 100 is a low-pass filter 23 for removing offset and high-frequency noise.
Is input to the floor stiffness estimating circuit 24. The floor stiffness estimating circuit 24 has the movement information s of the exposure XY stage.
tg is input. Here, the movement information of the XY stage refers to the coordinates of the XY stage measured by the laser interferometer,
This refers to information such as the acceleration of the XY stage corresponding to the force generated by the drive motor, and may include a predetermined moving weight for each driving direction of the XY stage.

The floor stiffness estimating circuit 24 calculates an exciting force transmitted to the floor 100 from the input movement information of the XY stage, and calculates the calculated exciting force and the second acceleration sensor 2.
2 is calculated based on the floor vibration obtained from
The proportional gain and the integral gain of the compensator 10 'are reset to optimal values. Here, the above-described proportional gain acts as a damping coefficient of the vibration damping table, and the integral gain operates like a spring coefficient of the vibration damping table.

The proportional gain and the integral gain to be changed may be obtained by using an arithmetic expression obtained from a strict equation of motion, or by learning using an evaluation function of fuzzy control or the like. In the case where the proportional gain and the integral gain of the PI compensator 10 'of the active vibration isolator of this embodiment are reset to optimal values, the exposure XY stage is adjusted to a drive pattern for adjustment, for example, the entire drive range. The measurement may be performed with a high S / N ratio by driving in a reciprocating driving pattern or a driving pattern in which the acceleration of acceleration / deceleration is higher than that in normal driving. Although FIG. 1 illustrates one vertical acceleration sensor, for example, a plurality of acceleration sensors may be used to detect a multiaxial component of floor vibration.

(Second Embodiment) FIG. 2 is a diagram showing a configuration of an active vibration isolator using a VCM as an actuator on which an exposure XY stage of a semiconductor exposure apparatus is mounted. FIG.
In the figure, the parts denoted by the same reference numerals as those in FIG. 4 are configured and operate in the same manner as those in FIG.

The difference between the apparatus shown in FIG. 2 and the apparatus shown in FIG. 4 is that the first acceleration sensor 8
, A PI compensator 18 capable of changing the proportional gain and the integral gain of the feedback loop, a second acceleration sensor 22 installed on the installation floor 100 of the device, a DC cut low-pass filter 23, and a floor rigidity estimation circuit 24 are added. And that the P compensator 10 has been changed to a PI compensator 10 '.

In FIG. 2, the output of the acceleration sensor 22 for measuring the acceleration (vertical direction) of the floor is input to a floor stiffness estimating circuit 24 via a low-pass filter 23 for removing offset and high-frequency noise. . Further, the movement information stg of the exposure XY stage is input to the floor rigidity estimation circuit 24.

The floor stiffness estimating circuit 24 calculates the exciting force transmitted to the floor 100 from the input movement information of the XY stage, and calculates the calculated exciting force and the second acceleration sensor 2.
The floor stiffness is calculated from the floor vibration obtained from Step 2, and the proportional gain and the integral gain of the PI compensator 18 are reset to optimal values. Here, the above-described proportional gain acts as a damping coefficient of the vibration damping table, and the integral gain operates like a spring coefficient of the vibration damping table.

The floor stiffness estimating circuit 24 may be configured to reset the proportional gain and the integral gain of the PI compensator 10 'instead of the proportional gain and the integral gain of the PI compensator 18. .

The effects of the first and second embodiments are as follows. (1) The size of semiconductor manufacturing equipment is increasing with the increase in diameter of semiconductor wafers. Further, the pattern line width to be printed on a semiconductor wafer has been miniaturized year by year. Therefore, it is necessary to increase the floor rigidity of the floor on which the semiconductor manufacturing apparatus is installed. However, for this purpose, the construction cost of the semiconductor factory building increases significantly. When the semiconductor exposure apparatus using the anti-vibration table controller of the above embodiment is installed on such an installation floor, there is an effect that sufficiently good printing accuracy can be maintained even with the conventional floor rigidity. (2) If the floor rigidity is uniform over the entire floor on which the device is installed, the damping coefficient and the spring constant can be adjusted optimally according to the state of the floor on which the device is installed. However, due to the uneven load of the semiconductor manufacturing equipment and the unevenness of the floor rigidity, X
Depending on the step-and-repeat or step-and-scan of the Y stage, the vibration transmission rate and the vibration direction to the floor are different, which causes variation in positioning time and accuracy. According to the above embodiment, there is an effect that these variations can be suppressed. (3) Since the control device of the vibration isolation table of the above embodiment can measure the floor vibration and floor rigidity of the floor on which the vibration isolation table is installed, it is necessary to perform autonomous tuning for each installation location. Becomes possible. Therefore, there is an effect that the installation start-up time of the device can be shortened. (4) This has the effect of contributing to the productivity of the semiconductor manufacturing apparatus.

(Embodiment of Device Production Method) Next, an embodiment of a device production method using an exposure apparatus supported by using the above-described active vibration isolator (active damper) will be described. FIG. 5 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), 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 (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. 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. 6 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 active damper 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
In (resist removal), 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.

[0030]

According to the present invention, the characteristics such as the damping coefficient and the integral gain of the active damper are changed in accordance with the rigidity of the installation floor. Vibration performance can be maximized, and device manufacturing accuracy and throughput can be improved without particularly strengthening the floor on which the device manufacturing apparatus is installed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an active vibration isolator using an air spring as an actuator according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of an active vibration isolator using a pneumatic spring and a voice coil motor as an actuator according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a conventional active vibration isolator using an air spring as an actuator.

FIG. 4 is a diagram showing a configuration of a conventional active vibration isolator using an air spring and a voice coil motor as actuators.

FIG. 5 is a diagram showing a flow of manufacturing a micro device.

FIG. 6 is a diagram showing a detailed flow of a wafer process in FIG. 5;

[Explanation of symbols]

1: servo valve, 2: air spring, 3: position sensor,
4: Vibration isolation table, 5: mechanical spring for preload, 6: viscous element, 7:
Feedback device, 8: acceleration sensor, 9: DC cut low-pass filter, 10: P compensator, 10 ': PI compensator, 11: voltage-current converter, 12: displacement amplifier, 1
3: comparison circuit, 14: target voltage, 15: PI compensator, 1
6: air spring type support leg, 17: integrator, 18: PI compensator, 19: power amplifier, 20: voice coil motor (V
CM), 21: VCM type support leg, 22: acceleration sensor,
23: DC cut low-pass filter, 24: floor rigidity estimation circuit, 100: installation floor, stg: stage information.

Claims (7)

[Claims] In a device manufacturing apparatus in which at least a movable portion is supported on an installation floor via an active damper, means for measuring rigidity of the installation floor, and means for changing characteristics of the active damper according to the measurement A device manufacturing apparatus comprising: 2. The device manufacturing apparatus according to claim 1, further comprising a sensor for measuring the vibration of the installation floor, and estimating a floor rigidity from an output of the sensor accompanying operation of the device manufacturing apparatus. 3. The device manufacturing apparatus according to claim 2, wherein said sensor is an acceleration sensor. 4. An active damper, comprising: a vibration isolation table on which a movable section including an XY stage is mounted; elastic support means for elastically supporting the vibration isolation table; an actuator for driving the vibration isolation table; A first vibration sensor that detects the vibration of the vibration isolation table, a vibration control compensator that feeds back the output of the first vibration sensor, a displacement sensor that detects the displacement of the vibration isolation table, Position control compensating means for feeding back an output, at least one second vibration sensor for detecting the vibration of the installation floor, and measuring the vibration of the installation floor accompanying the driving of the movable object by the second vibration sensor 3. The device manufacturing apparatus according to claim 2, further comprising: means for estimating the rigidity of the installation floor; and means for adjusting characteristics of the active damper. 5. The device manufacturing apparatus according to claim 4, wherein at least one of an air spring and a voice coil motor is used as said actuator. 6. The device manufacturing apparatus according to claim 1, wherein a spring constant and a damping coefficient are adjusted as characteristics of the active damper. 7. A device manufacturing method, wherein a device is manufactured by the device manufacturing apparatus according to claim 1.