JPH1187472A - Substrate delivery device, device manufacturing apparatus and device manufacturing method - Google Patents

Abstract

(57) [Problem] To improve the servo rigidity of a temporary support portion in order to transfer a substrate with high accuracy. SOLUTION: A temporary support portion having a temporary support surface for temporarily supporting a substrate, driving means for rotating the temporary support portion around an axis orthogonal to the temporary support surface of the temporary support portion, A substrate transfer having a measuring means for measuring a position in the rotation direction, and a position servo means for servo-controlling the position of the temporary support in the rotation direction by controlling the driving means based on the measurement value of the measuring means. In the apparatus, gain changing means is provided for changing the gain of the position servo means when the substrate is held on the temporary support surface and when the substrate is not held on the temporary support surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer apparatus for transferring a substrate (semiconductor substrate (wafer), a glass substrate of a liquid crystal display device, etc.) to a stage, and to transfer the semiconductor substrate to a desired position. TECHNICAL FIELD The present invention relates to a device manufacturing apparatus such as an exposure apparatus for manufacturing a semiconductor integrated circuit that performs processing by using a semiconductor device, and a method of manufacturing a device such as a semiconductor element or a liquid crystal display element using such a device manufacturing apparatus.

[0002]

2. Description of the Related Art In a lithography process in the manufacture of a semiconductor integrated circuit, a step-and-repeat type (including a step-and-scan type) reduced projection type exposure apparatus,
A so-called stepper plays a central role. In this stepper, it is necessary to improve the performance of the wafer stage year by year with respect to reduced line radiation of a circuit formed on the order of submicron, and there is an increasing demand for simultaneously satisfying high speed and high accuracy. The structure inside the wafer stage is simple and a mechanism as light as possible is important for high-speed and high-precision positioning. For example, JP-A-7-1112
According to Japanese Patent Publication No. 38, it is possible to realize a lightweight wafer stage having a long stroke in the Z (vertical) direction.
On the other hand, in order to increase productivity, the size of the wafer is also increasing, and there is a high possibility that the wafer will be shifted from the current 8 inches to a large wafer such as 12 inches in the future.

In a so-called alignment process for aligning a pattern formed on a wafer, a wafer roughly aligned in the θ direction (rotational direction around the Z axis) based on the outer shape is received by a wafer chuck. Then, after the θ position shift is measured by the alignment microscope and θ sub position alignment is performed, further precise position measurement is performed. At this time, it is difficult to form a notch in the wafer chuck that uniformly holds the back surface of the wafer. Therefore, in order to transfer the wafer to the wafer chuck, the wafer is once placed on the temporary support portion and then placed on the wafer chuck. Methods are being used. In the temporary support portion, for example, a negative pressure suction hole is provided on a temporary support surface on which a wafer is placed.
A book pin is used.

In order to perform θ sub-positioning,
The temporary support has a θ drive mechanism. The actual measurement of the θ position shift and the θ sub-positioning are as follows. In other words, when measuring the θ position shift of the wafer, it is necessary to perform an up-down operation to adjust the wafer surface within the depth of focus of the alignment microscope. Therefore, the θ position shift is measured with the wafer placed on the chuck. Next, with the wafer placed on the temporary support,
Based on the θ position deviation measurement result, θ sub position alignment is performed. This eliminates the need for a mechanism for vertically moving the temporary support, thereby simplifying and reducing the weight of the mechanism.

[0005]

At this time, a problem is a positional deviation occurring at the time of delivery. In order to minimize the displacement, it is desirable to overlap the negative pressure suction of the temporary support and the negative pressure suction of the wafer chuck at the time of delivery. At this time, the temporary support is connected to the chuck via the wafer, and the contact state of the temporary support
A disturbance force may be applied to the drive mechanism in an unexpected direction.
In order to reduce the displacement that occurs during delivery, the θ drive mechanism of the temporary support must have high rigidity so that it does not rotate due to disturbance force. For that purpose, the position servo gain of the θ drive mechanism Must be as high as possible.

However, when the weight of the stage and the temporary support portion is reduced for high-speed and high-accuracy stages, or when a large-sized wafer which has recently been used is used, the servo system becomes unstable when the servo gain is increased. Cheap. For this reason, there is a problem that the gain cannot be sufficiently increased, the servo stiffness is insufficient, and a transfer error is likely to occur.

[0007] The present invention has been made in view of such a point, the purpose is to increase the servo rigidity of the temporary support portion,
It is an object of the present invention to provide a substrate delivery apparatus and a device manufacturing apparatus that enable high-accuracy delivery.

[0008]

In order to achieve the above object, a substrate delivery apparatus according to a first aspect of the present invention comprises: a temporary support portion having a temporary support surface for temporarily supporting a substrate; A driving unit that rotates the temporary support unit about an axis orthogonal to the temporary support surface, a measurement unit that measures the position of the temporary support unit in the rotation direction, and the driving unit based on a measurement value of the measurement unit. And a position servo means for servo-controlling the position of the temporary support portion in the rotation direction by controlling the position of the temporary support portion. The gain of the position servo means is changed between when the substrate is held on the support surface and when the substrate is not held on the temporary support surface.

In order to achieve the above object, a substrate transfer device according to a second aspect of the present invention includes a temporary support portion having a temporary support surface for temporarily supporting a substrate, and a substrate support on the temporary support surface. Suction means for sucking and holding, driving means for rotating the temporary support portion about an axis orthogonal to the temporary support surface of the temporary support portion, measuring means for measuring the position of the temporary support portion in the rotation direction, and And a position servo means for servo-controlling the position of the temporary support in the rotation direction by controlling the driving means based on the measurement value of the measuring means. Suction state determination means for determining whether the state is the suction state,
A gain changing means for changing a servo gain of the position servo means, and when the suction means is in a suction state,
The gain of the position servo means is changed when the suction means is not in the suction state. The determination of the suction state is performed, for example, by measuring the suction pressure of the suction means.

[0010]

At present, it is required to reduce the weight of the stage in order to increase the speed and accuracy of the stage, and it is necessary to reduce the weight of the temporary support. On the other hand, the wafer size is increasing,
Weight also tends to increase. Therefore, the mass of the wafer is largely changed between the state where the wafer is held on the temporary support portion and the state where the wafer is not held. When the servo gain is increased, the gain margin and the phase margin become smaller, and the servo system tends to become unstable due to load fluctuation and mass fluctuation. Therefore, in the conventional apparatus, when a large wafer is used, the gain can be sufficiently increased to cope with both the state where the wafer is held on the temporary support portion and the state where the wafer is not held. However, there is a problem that the transfer is likely to occur.

According to the present invention, the position servo is changed by changing the servo gain of the position servo means of the temporary support between when the wafer is held on the temporary support and when the wafer is not held. The servo gain can be increased without making the means unstable, and the servo rigidity of the temporary support portion can be increased. As a result, the transfer gap can be reduced.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. 1 is a drawing showing a configuration of a substrate transfer device portion of a semiconductor manufacturing apparatus (stepper) according to an embodiment of the present invention. In this figure, W is a substrate such as a semiconductor wafer to be aligned (hereinafter referred to as a wafer),
WC is a suction surface W that holds the wafer W by suction so as to keep the wafer W flat.
A wafer chuck having CS, WH is a wafer hand for positioning the wafer W in the outer shape in advance and placing the wafer W on the temporary support TC, and the temporary support TC has a temporary support surface TCS and temporarily supports the wafer W. As a result, the gap between the wafer chuck WC and the wafer W is secured at least by the thickness of the wafer hand WH.

A wafer feeder WF for driving a wafer hand WH to position the outer shape of the wafer W at a desired position;
OA is a microscope for observing an alignment mark on the wafer W and measuring a positional shift thereof, XY is an XY stage for performing two-dimensional movement in the horizontal (XY) direction, Z is an XY stage for fixing the wafer chuck WC and A top plate serving as a Z stage movable in the vertical (Z) direction with respect to XY, and a linear motor ZM is installed on the XY stage XY and serves as a driving means for moving the top plate Z in the vertical (Z) direction. , ZS are installed on the XY stage XY,
This is a displacement sensor serving as a measuring means for measuring the vertical displacement of the sensor.

The MD is connected to the motor ZM.
A motor driver (drive device) that controls the drive current (i) to the motor DF, and DF represents the deviation (e) between the target value (c) output from the control device C and the current value (y) output from the displacement sensor ZS. The differentiator MC to be determined is connected to the motor driver MD and is a servo control device for converting the deviation (e) calculated by the differentiator DF into the operation amount (I), and these constitute a position servo means. The motor driver MD drives the motor ZM based on the operation amount (I). M is a mirror which is installed on the top plate Z and serves as a measurement reference for the displacement of the XY stage XY in the XY directions. The mirror M has a laser interferometer (not shown) from the XY stage XY.
A laser beam is applied to measure the displacement in the Y direction.
QM is a θ motor that is installed on the XY stage XY and rotates the temporary support TC in the θ direction on the XY stage XY.

The PST is connected to the temporary support TC via a pipe, the temporary support pressure sensor for measuring the suction pressure at the temporary support TC, and the PSC is connected to the wafer chuck WC via a pipe, and the suction at the wafer chuck WC. A wafer chuck pressure sensor SVT for measuring pressure is disposed in a pipe connecting the temporary support portion TC and the negative pressure source VS, and is a switching valve for switching the pressure of the wafer chuck WC between atmospheric pressure and negative pressure (suction pressure). is there.

The above-described control device C controls the suction pressure of the temporary support TC (output of the temporary support pressure sensor PST) and the suction pressure of the wafer chuck WC (the wafer chuck pressure sensor PST).
SC output) and the motor drive current (i), and also generates a command output to the displacement sensor target value (c) and the temporary support switching valve SVT and the wafer chuck switching valve SVC.

A difference (e) is obtained by a differentiator DF from the measured value (y) from the displacement sensor ZS and a target value (c) generated by the control device C. Servo controller MC has deviation (e)
Is converted into an operation amount (I) for the motor ZM to be given to the drive device MD. With these configurations, the top plate Z is servo-positioned at a desired position in the vertical (Z) direction.

A difference (eq) is obtained by a differentiator QDF from the measured value (yq) from the displacement sensor QS and the target value (cq) generated by the control device C. Servo controller QMC
Converts the deviation (eq) into an operation amount (Iq) for the motor QM to be given to the driving device QMD based on the servo gain (Gq) given from the control device C. With these configurations, the temporary support portion TC is servo-positioned at a desired position in the rotation (θ) direction.

First, a control device C serving as a control means is configured so that the suction surface WCS of the wafer chuck WC is moved to the temporary support surface T of the temporary support portion TC.
The target value (c) is set so as to be sufficiently lower than CS. Next, the wafer W roughly positioned according to the outer shape by the wafer feeder WF is placed on the wafer hand WH and moves onto the temporary support portion TC. The control device C opens the temporary support switching valve SVT to the negative pressure side, and the wafer W is moved to the temporary support T.
Wait for being put on C. The wafer hand WH descends in the Z direction at a sufficiently low speed so that no positional displacement occurs.
Eventually, the back surface of the wafer W becomes the temporary support surface TCS of the temporary support portion TC.
And the wafer W is supported by the temporary support portion TC. At this time, the control device C changes the servo gain (Gq) of the servo control device QMC to a gain for mounting a wafer. After the front surface of the wafer hand WH descends to a position away from the rear surface of the wafer W, the wafer hand WH is returned along the XY plane to a position where it does not interfere with the wafer chuck WC. At the same time, the control device C moves the XY stage XY along the XY plane to a position where the wafer chuck WC and the wafer hand WH do not interfere.

Next, the control device C slowly raises the target value (c) corresponding to the measurement value (y) of the displacement sensor ZS so that the suction surface WCS of the wafer chuck WC approaches the back surface of the wafer W. . Then, the wafer chuck switching valve SVC is switched to the negative pressure side. Wafer chuck WC
After the top plate Z rises in the Z direction until the suction surface WCS of the wafer is higher than the back surface of the wafer W supported by the temporary support portion TC, the measured value of the wafer chuck pressure sensor PSC reaches a desired pressure. , The control device C is a temporary support switching valve SV
Open T to atmospheric pressure. On the way, when the suction surface WCS of the wafer chuck WC becomes the same height as the back surface of the wafer W supported by the temporary support portion TC, the controller C changes the servo gain (Gq) of the servo controller QMC to the wafer. Change the gain for when not installed.

As a result, the wafer W is placed on the wafer chuck WC.
From the temporary support portion TC, and the wafer chuck WC
Will be changed to During this time, since the wafer W is always sucked and held by one of the wafer chuck WC and the temporary support portion TC, a shift generated when the wafer W is changed is small.

The controller C sets a target value (c) corresponding to the measurement value (y) of the displacement sensor ZS so that the surface of the wafer W sucked negatively on the wafer chuck WC is within the depth of focus of the microscope OA. Set. Then, after the surface of the wafer W falls within the depth of focus of the microscope OA, the control device C
Microscope OA is used to displace the two alignment marks
To determine the position shift of the wafer W in the XYθ directions.

Next, the controller C monitors the current value (i), and if the change exceeds a certain range, immediately waits for the wafer chuck switching valve SVC to open to the atmospheric pressure side.
The current value (i) from the motor driver MD to the motor ZM is almost constant if the change of the target value (c) corresponding to the measurement value of the displacement sensor ZS is sufficiently slow.

Thereafter, the control device C operates the temporary support switching valve SV.
T is opened to the negative pressure side, and the target value (c) of the displacement sensor ZS is slowly lowered. When the back surface of the wafer W comes into contact with the temporary support surface TCS of the temporary support portion TC, a weak force acts on the rear surface of the wafer W upward from the temporary support portion TC. Then, the deviation (e) between the measurement value (y) of the displacement sensor ZS and its target value (c) increases, and the operation amount (I) of the servo controller MC and the motor current value (i) from the motor driver MD.
Changes in a direction to reduce the deviation (e). At this time,
The temporary support surface TCS of the temporary support portion TC and the suction surface WCS of the wafer chuck WC are at the same height. In this state, the negative pressure suction of the temporary support portion and the negative pressure suction of the wafer chuck overlap each other. Then, the control device C changes the servo gain (Gq) of the servo control device QMC to a gain for mounting a wafer, and opens the wafer chuck switching valve SVC to the atmospheric pressure side. As described above, the positional shift of the wafer W when the temporary support surface TCS of the temporary support portion TC and the suction surface WCS of the wafer chuck WC are at the same height is small.

Next, the suction surface WCS of the wafer chuck WC
After confirming that the atmospheric pressure has become sufficiently atmospheric pressure, the target value (c) of the displacement sensor ZS is lowered more slowly. At this time, if the descending speed is high, the air does not sufficiently flow through the negative pressure suction holes formed around the wafer chuck WC and the suction surface WCS, so that the back surface of the wafer W and the wafer chuck WC suction surface WCS momentarily Negative pressure (hereinafter referred to as dynamic negative pressure). The dynamic negative pressure applies stress to the wafer W, causing unpredictable deformation such as warpage. If the stress is larger than the allowable amount, the wafer W is displaced in spite of being suction-supported by the temporary support portion TC.

The dynamic negative pressure acts upward on the top plate Z which is about to descend at a constant speed, and becomes a load on the motor ZM. Therefore, the magnitude of the dynamic negative pressure is observed in the manipulated variable (I) and the motor current (i). Therefore, the top is lowered so that the operation amount does not exceed a predetermined value. Thereby, the stress on the wafer W due to the dynamic negative pressure is suppressed to the allowable capacity or less, and the displacement when the wafer chuck WC is lowered is reduced.

The control device C controls the wafer W measured by the microscope OA.
The θ sub-positioning is executed by rotating the θ motor QM for the positional deviation in the θ direction. Next, the temporary support T
From C, a change to the wafer chuck WC is performed. On the way, the suction surface WCS of the wafer chuck WC is
The controller C changes the servo gain (Gq) of the servo controller QMC to a gain for non-wafer mounting when the height becomes the same as the back surface of the wafer W supported by the wafer.

Finally, X of the wafer W measured by the microscope OA
While shifting the Y direction by moving the XY stage XY, the XY stage XY moves the wafer W to a pattern projection position of a projection optical system (not shown) for exposing and projecting a pattern for manufacturing a semiconductor integrated circuit on a reticle. Then, pattern exposure on the wafer W is performed in a step-and-repeat manner.

In the course of the above series of transfer operations,
The servo gain (Gq) of the servo controller QMC of the temporary support TC is appropriately switched by the controller C depending on whether or not the wafer W is mounted. Therefore, the servo rigidity of the temporary support portion TC can be kept high irrespective of whether the wafer W is mounted or not, and it is possible to reduce the transfer deviation.

The servo controllers MC and QMC and the difference units DF and QDF do not need to be realized by hardware, and include a numerical processor (DSP) including the controller C.
It may be realized by software on the above.

Second Embodiment In the first embodiment, the servo gain (Gq) of the servo control device QMC of the temporary support TC is changed by the motor driver MD.
Is switched based on the motor current value (i) from the temporary support section TC (temporary support section pressure sensor PS).
T output). That is, when the suction pressure of the temporary support TC is in a negative pressure state, the wafer W is mounted on the temporary support surface TCS, and therefore, the servo gain (Gq) of the servo control device QMC of the temporary support TC. To the gain when the wafer is mounted. On the other hand, the temporary support portion TC
When the suction pressure of the wafer W is in the atmospheric pressure state, the wafer W
Are not mounted on the temporary support surface TCS, the servo gain (Gq) of the servo control device QMC of the temporary support portion TC is changed to the gain when the wafer is not mounted.

The servo gain (Gq) of the servo controller QMC of the temporary support TC is continuously changed from the gain when no wafer is mounted to the gain when the wafer is mounted according to the change in the suction pressure of the temporary support TC. May be changed.

[0033]

[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. 2 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. 3 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. In step 16 (exposure), the circuit pattern on the mask is printed and exposed on the wafer by the exposure apparatus having the above-described substrate transfer apparatus. 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 produce a highly integrated device, which was conventionally difficult to produce, at low cost.

[0036]

As described above, according to the present invention,
By changing the servo gain of the position servo means of the temporary support portion between when the wafer is held on the temporary support portion and when the wafer is not held, the servo is performed without destabilizing the position servo means. The gain can be increased, and the servo rigidity of the temporary support can be increased. As a result, the transfer gap can be reduced.

[Brief description of the drawings]

FIG. 1 is a view showing a substrate transfer device according to one embodiment of the present invention.

FIG. 2 is a diagram showing a flow of manufacturing a micro device.

FIG. 3 is a diagram showing a detailed flow of a wafer process in FIG. 2;

[Explanation of symbols]

W: wafer, WC: wafer chuck, WCS: suction surface,
TC: temporary support portion, TCS: temporary support surface, WF: wafer feeder, OA: microscope, XY: XY stage, Z: top plate,
ZM: motor, ZS: displacement sensor, MD: motor driver, DF: differentiator, MC: servo controller, M: mirror, QM: θ motor, QS: θ displacement sensor, QMD: θ
Motor driver, QDF: θ differentiator, QMC: θ servo controller, PST: Temporary support pressure sensor, PSC: Wafer chuck pressure sensor, SVT: Temporary support switching valve, SV
C: Wafer chuck switching valve, C: Control device.

Claims (5)

[Claims] A temporary support portion having a temporary support surface for temporarily supporting a substrate; a driving unit for rotating the temporary support portion around an axis orthogonal to the temporary support surface of the temporary support portion; A substrate having measuring means for measuring the position in the rotational direction, and position servo means for servo-controlling the position of the temporary support in the rotational direction by controlling the driving means based on the measurement value of the measuring means; The delivery device may further include a gain changing unit that changes a gain of the position servo unit when the substrate is held on the temporary support surface and when the substrate is not held on the temporary support surface. A substrate delivery device characterized by the above-mentioned. 2. A temporary support portion having a temporary support surface for temporarily supporting a substrate, suction means for sucking and holding the substrate on the temporary support surface, and an axis perpendicular to the temporary support surface of the temporary support portion. A driving unit that rotates the temporary support unit, a measurement unit that measures the position of the temporary support unit in the rotation direction, and a control unit that controls the drive unit based on a measurement value of the measurement unit to control the provisional support unit. In a substrate transfer apparatus having a position servo unit that servo-controls the position in the rotation direction, an adsorption state determination unit that determines whether the adsorption unit is in an adsorption state or a non-adsorption state, and when the adsorption unit is in an adsorption state. And when the suction means is not in the suction state,
A substrate transfer device comprising: a gain changing unit that changes a gain of the position servo unit. 3. The suction state determining unit according to claim 2, wherein the suction state determination unit determines whether the suction unit is in a suction state or a non-suction state by measuring a suction pressure of the suction unit. Board transfer device. 4. A device manufacturing apparatus comprising the substrate transfer device according to claim 1. 5. A device manufacturing method, wherein a device is manufactured using the device manufacturing apparatus according to claim 4.