JP3003863B2 - Planar positioning device and method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention] (Industrial application field) The present invention relates to a plane positioning apparatus suitable for being incorporated in a semiconductor exposure apparatus, a semiconductor inspection apparatus, an ultra-precision processing apparatus, and the like.

(Prior Art) As is well known, when manufacturing a semiconductor device using an optical stepper, it is necessary to accurately position a wafer surface to be exposed at right angles to an optical axis of a projection lens and at an image forming position. .

By the way, as a so-called plane positioning device for positioning the wafer surface at right angles to the optical axis of the projection lens as described above, the following is conventionally considered. That is, as a representative example,
An apparatus disclosed in Japanese Patent Publication No. 36 can be mentioned. The apparatus disclosed in this publication has one set of feed mechanisms provided in the X direction, two sets of feed mechanisms provided in the Y direction, and three sets of feed mechanisms provided in the Z direction. A transmission member that transmits only the force in the feed direction of each feed mechanism and allows movement in a direction other than the feed direction is interposed between the six feed mechanisms and the stage, and the six feed mechanisms are independently provided. The stage can be directly driven. In order to actually align the wafer surface with the focal plane of the projection optical system, nine positions set on the wafer surface are measured using a capacitance type proximity sensor, and these nine positions and the focal position are measured. Is obtained, and from this, the shift amount and the tilt amount between the approximate plane of the entire wafer and the focal plane of the projection optical system are obtained.
Based on the shift amount and the tilt amount obtained in this way, the above-mentioned three sets of feed mechanisms in the Z direction are controlled so that the approximate plane of the entire wafer is adjusted to the focal plane of the projection optical system.

However, the apparatus configured as above has the following problems. That is, in order to improve the throughput, it is necessary to use a large-diameter wafer so that a plurality of chips can be obtained from one wafer. In general, it is difficult to increase the flatness of the surface of a wafer having such a large diameter, and in many cases, the wafer is slightly warped. On the other hand, in order to transfer a fine pattern onto a wafer, it is necessary to use a light source having a short wavelength as the light source of the projection optical system or to increase the numerical aperture of the projection lens in the projection optical system. However, these methods cause a decrease in the depth of focus of the projection lens.

As can be seen from the above description, it is necessary to use a large-diameter wafer having a warp or the like in order to improve the throughput. To transfer a fine pattern onto a wafer, it is necessary to use a light source with a short wavelength as the light source of the projection optical system or to increase the numerical aperture of the projection lens. Invite. When the pattern is transferred in such a state where the depth of focus is shallow, the transfer accuracy deteriorates even when the surface position of the wafer slightly changes.

Therefore, as in the above-described conventional apparatus, the method of initially aligning the approximate plane of the entire wafer with the focal plane of the projection optical system and performing transfer to each part in this state does not allow a large-diameter wafer having warpage or the like to exist. When used, there is a problem that high-accuracy transfer cannot be performed.

(Problems to be Solved by the Invention) As described above, in the conventional planar positioning device, if it is to be applied to, for example, an optical stepper, particularly when the depth of focus is small and the diameter of the wafer is large, the accuracy is low. There was a problem that high transfer could not be performed essentially.

Therefore, the present invention is to provide a planar positioning device which can solve the above-mentioned disadvantages and can contribute to high-accuracy transfer realization when applied to, for example, an optical stepper for a wafer having a small depth of focus and a large aperture. It is an object.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, a planar positioning device of the present invention is provided with a first table and a plurality of partitioned areas mounted on the first table. Based on a second table for placing a plane positioning object on which a surface is set, and a rectangular coordinate system composed of an X axis, a Y axis, and a Z axis, the first table is at least in the X axis direction or the Y axis. Driving means for driving the second table in a Z-axis direction, a rotation direction about an X-axis, and a rotation direction about a Y-axis; and the planar positioning. Measuring means for simultaneously measuring at least three positions in the Z-axis direction on the sectioned area surface on which the object is to be positioned, and Z based on a reference plane based on an output signal of the measuring means.
Calculating means for calculating the axial position error amount, the X-axis direction rotation error amount, and the Y-axis direction rotation error amount;
First control means for providing a control signal to the second drive means so as to reduce the respective error amounts obtained by the calculation means to zero, and a section to be positioned by the first control means A second control unit for providing a control signal to the first drive unit to move a sectioned region surface to be positioned next to a position measurable by the measurement unit after the plane positioning of the region surface is completed. It is characterized by its provision.

Further, the planar positioning method of the present invention includes a first table and a second table for placing a planar positioning target placed on the first table and having a plurality of partitioned area surfaces set thereon.
And first driving means for driving the first table at least in the X-axis direction or the Y-axis direction with reference to rectangular coordinates consisting of the X-axis, the Y-axis, and the Z-axis. Second driving means for driving the table in the Z-axis direction, the X-axis rotation direction, and the Y-axis rotation direction, respectively, and at least three positions on the partitioned area surface on which the planar positioning target is to be positioned; Measuring means for simultaneously measuring a position; and a position error amount in the Z-axis direction, a rotation error amount in the X-axis direction, and a rotation in the Y-axis direction on the section plane with respect to the reference plane based on the output signal of the measuring means. In a planar positioning method for positioning a planar positioning target using a planar positioning device including a calculation unit for calculating an error amount, a positioning pair of the plurality of partitioned area surfaces Moving the first table by the first drive means to a position where the section area surface to be measured can be measured by the measuring means; and at least three positions on the section area surface to be positioned. Simultaneously measuring the position of the reference plane with the measuring means, and calculating the Z-axis position error, the X-axis rotation error, and the Y-axis rotation error with respect to a reference plane based on the measurement result. And a step of giving a control signal to the second drive means to set the respective error amounts obtained by the calculation results to zero, thereby positioning the partitioned area surface to be positioned, and Performing a predetermined process on the partitioned area surface, and after completing the predetermined process, the next partitioned area surface to be positioned among the plurality of partitioned area surfaces is subjected to the measurement. A measurable position in stages, is characterized by comprising the step of repeating the sequence above step so as to move the first table by the first driving means.

(Operation) For each of a plurality of partitioned area planes defined on the positioning target plane of the planar positioning target, three positions of the partitioned area plane are simultaneously measured, and the Z-axis direction position of the partitioned area plane relative to the reference plane is measured. Since the means for calculating the error amount, the X-axis rotation error amount, and the Y-axis rotation error amount are provided, it is not necessary to move the planar positioning object in the XY-axis direction to calculate the above error amounts. Therefore, the Z-axis direction position error amount, the X-axis rotation error amount, and the Y-axis rotation error amount can be calculated almost instantaneously. Further, since the above-described error amount calculating means is provided, feedback control can be performed on the first control means. Therefore, it is possible to reliably compensate for disturbance. In addition, since the control system is configured so that each of the plurality of partitioned area planes defined on the positioning target plane of the target object is aligned with the reference plane, for example, the depth of focus is shallow, and the warpage is low. In the case where the present invention is applied to an optical stepper for a large-diameter wafer having such a large diameter, it can contribute to realization of highly accurate transfer.

(Example) Hereinafter, an example is described with reference to drawings.

FIG. 1 is a schematic perspective view of a flat positioning device according to an embodiment applied to a semiconductor exposure system.

The mechanically movable part of this device is an X
With reference to a rectangular coordinate system consisting of an axis, a Y-axis, and a Z-axis, a table 1 movably arranged in the Z-axis direction on an XY table (not shown), and the table 1 is selectively moved in the Z-axis direction. A first drive mechanism 2, a first support mechanism 3 arranged on the Y axis on the table 1, and a movably arranged in the Z axis direction at a symmetrical position on the table 1 with respect to the Y axis. Second and third support mechanisms 4, 5 and a second drive mechanism 6 and a third drive mechanism for selectively moving the second support mechanism 4 and the third support mechanism 5 in the Z-axis direction. 7. Each of the drive mechanisms 2, 6, and 7 is a mechanism that combines a motor and a reduction gear including a ball screw.
Alternatively, a combination of piezoelectric elements is used. These drive mechanisms 2, 6, 7 are controlled by first, second, and third servo mechanisms 8, 9, 10, respectively.

On the other hand, on the upper surfaces of the support mechanisms 3, 4, 5
A wafer table 11 that is point-supported is placed, and on the upper surface of the wafer table 11, a wafer 12 as a planar alignment target is supported. Above or obliquely above the wafer table 11, just above the upper surface of the wafer 12,
Simultaneously measure the three positions P ₁ , P ₂ , and P ₃ of the wafer chip 13 at the exposure position in the Z-axis direction, and position the wafer chip 13 in the Z-axis direction Zl, X-axis rotation angle Xθ, and Y-axis rotation. detects the angular Y.theta, Z-axis direction position signal Zl _1, X-axis rotational angle signal X.theta _1, Y-axis rotational angle signal Y.theta ₁ displacement meter 14 that outputs are provided. Then, the Z-axis direction position signal Zl ₁ servo mechanism 8 which is output from the displacement meter 14, X-axis rotational angle signal X.theta ₁ to the servo mechanism 9, also, Y-axis rotational angle signal Y.theta ₁ is servomechanism 10 Is input to

The servo mechanisms 8, 9, 10 are specifically configured as shown in FIG. That is, the servo mechanism 8 includes the subtractor 21
Derives a deviation between the Z-axis direction reference position signal Zl _S and the Z-axis direction position signal Zl _1, and supplies this error signal Zl ′ as an input signal to the driver circuit 22. The driver circuit 22 generates the error signal Z
The actuator of the drive mechanism 2 is driven corresponding to l '. The servo mechanism 9, the subtractor 23 takes the difference between the X-axis reference rotational angle signal X.theta _S and X-axis rotational angle signal X.theta _1,
The error signal Xθ ′ is added to the adder 25 through the interference compensating element 24.
And the output of the adder 25 is given as an input signal of the driver circuit 26. Driver circuit 26
Drives the actuator of the drive mechanism 6 in accordance with the input signal. The servo mechanism 10 includes a subtractor 27 takes the difference between the Y-axis reference rotational angle signal Y.theta _S and Y-axis rotation angle signal Y.theta _1, gain compensation element 28 the error signal Y.theta '
On the one hand to the other input of said adder 25 and on the other hand through an inverter 29 to an adder 30
To one input end. The other input terminal of the adder 30 has an error signal Xθ ′ passing through the interference compensating element 24.
Is given. Then, the output of the adder 30 is given as an input signal of the driver circuit 31. Driver circuit 31
Drives the actuator of the drive mechanism 7 in accordance with the input signal. As can be seen from the above signal flow, the driver circuit 26 of the servo mechanism 9 sets the signal to be given to the drive mechanisms 6 and 7 and the Y-axis rotation error signal to zero to make the X-axis rotation error signal zero. As an input, a signal obtained by adding signals to be supplied to the driving mechanism 6 among signals to be supplied to the driving mechanisms 6 and 7 is provided as an input. Further, the driver circuit 31 includes signals to be given to the driving mechanisms 6 and 7 to make the rotation error signal around the X axis zero, and driving mechanisms 6 and 7 to make the rotation error signal around the Y axis zero.
Of the signals to be supplied to the driving mechanism 7 are provided as inputs.

With such a configuration, when the target wafer chip 13 is sequentially sent to the exposure position by moving the XY table, the displacement meter 14 instantaneously outputs the Z-axis direction position signal Zl ₁ ,
An X-axis rotation angle signal Xθ ₁ and a Y-axis rotation angle signal Yθ ₁ are output. Then, servo is applied to the servo mechanisms 8, 9, and 10 by this output. Therefore, it is possible to accurately align the entire surface of the target wafer chip 13, that is, the entire surface of each partitioned area surface set on the positioning target surface of the target object, in a very short time. In addition, since the driving mechanisms 2, 6, 7 are controlled using the servo mechanisms 8, 9, 10, respectively, even if disturbance is introduced after positioning, this can be quickly compensated.

FIG. 3 shows servo mechanisms 8a, 9a and 10a in a plane positioning device according to another embodiment of the present invention. In this embodiment, interference between each other is prevented by using the interference compensation elements 41 and 42 and the adder 43. With this configuration, it is possible to expect not only the same effects as in the above-described embodiment, but also to perform the planar positioning control more smoothly and with higher responsiveness.

[Effects of the Invention] As described above, according to the present invention, for each of a plurality of partitioned area surfaces partitioned on the positioning target surface of the object,
Since the control system is configured so that this sectioned area plane is aligned with the reference plane, for example, when applied to an optical stepper for a large-diameter wafer having a small depth of focus and having a warp or the like, This can contribute to high-accuracy transfer.

[Brief description of the drawings]

1 is a schematic perspective view of a flat positioning device according to one embodiment applied to a semiconductor exposure system, FIG. 2 is a configuration diagram of a servo mechanism in the same device, and FIG. 3 is a drawing of a flat positioning device according to another embodiment. It is a block diagram of a servo mechanism. 1 ... table, 2 ... first drive mechanism, 3 ... first support mechanism, 4 ... second support mechanism, 5 ... third support mechanism, 6 ...
Second driving mechanism 7, 7 Third driving mechanism 8, First servo mechanism 9, Second servo mechanism 10, Third servo mechanism 11, Wafer table 13, … Wafer chips, 14 ……
Displacement gauge.

Claims (4)

(57) [Claims] 1. A first table, a second table placed on the first table for placing a planar positioning object on which a plurality of partitioned area surfaces are set, and an X-axis and a Y-axis. First driving means for driving the first table at least in the X-axis direction or the Y-axis direction with reference to the rectangular coordinates consisting of the axis and the Z-axis; and the second table in the Z-axis direction and the X-axis. Rotation direction, Y
Second driving means for driving each in the rotational direction around the axis; and measuring means for simultaneously measuring at least three Z-axis positions on the partitioned area surface as the positioning target of the planar positioning target. Calculating means for calculating the Z-axis direction error, the X-axis rotation error, and the Y-axis rotation error on the defined area plane with respect to the reference plane based on the output signal of the measuring means, And first control means for providing a control signal to the second drive means so as to reduce the respective error amounts obtained by the calculation means to zero; After the planar positioning of the partitioning area surface to be positioned is completed, a control signal is sent to the first driving means to move the partitioning area surface to be positioned next to a position measurable by the measuring means. And a second control means for providing the same. 2. The second driving means includes: a first driving mechanism for moving the entire second table in a Z-axis direction; and a second driving means disposed on the Y-axis on the first table. A first support mechanism; and a second and a third movably arranged in the Z-axis direction at symmetrical positions on the first table with respect to the Y-axis.
2. The planar positioning device according to claim 1, further comprising: a support mechanism configured to selectively move the second and third support mechanisms in the Z-axis direction. 3. apparatus. 3. The first and second driving mechanisms determine a deviation between a reference signal of the X-axis rotation error and a reference signal of the Y-axis rotation error, respectively. 3. The flat positioning device according to claim 2, wherein a signal is output via interference compensation means for compensating mutual interference between the driving mechanisms. 4. A first table, a second table for mounting a planar positioning object mounted on the first table and having a plurality of partitioned area surfaces set thereon, an X-axis and a Y-axis.
First driving means for driving the first table at least in the X-axis direction or the Y-axis direction with reference to rectangular coordinates consisting of an axis and a Z-axis; and driving the second table in the Z-axis direction and the X-axis direction. Second driving means for driving in the rotation direction and the rotation direction in the Y-axis direction, respectively, and measurement for simultaneously measuring at least three positions on the partitioned area surface to be positioned of the planar positioning object. Means and said Z with respect to a reference plane based on the output signal of said measuring means.
A plane positioning method for positioning a planar positioning object using a plane positioning apparatus including a calculating unit for calculating an axial position error amount, an X-axis rotation error amount, and a Y-axis rotation error amount, respectively. In the method, the first drive unit moves the first table to a position at which a partition area surface to be positioned among the plurality of partition area surfaces can be measured by the measurement unit, Simultaneously measuring at least three positions on the divisional area surface to be positioned by the measuring means, based on the measurement result, the Z-axis position error with respect to a reference plane, the X-axis rotation error, Calculating a rotation error amount about the Y-axis; and the second driving means for reducing the respective error amounts obtained from the calculation result to zero. Providing a control signal to the positioning area surface to be positioned, performing a predetermined process on the positioned partitioned area surface, and, after completing the predetermined process, the plurality of partitions. Repeating the above steps in such a manner that the first table is moved by the first driving means until the next sectioned area to be positioned in the area plane can be measured by the measuring means; A planar positioning method characterized by comprising: