JP2000058421A - Device for detecting position and aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the control performance of a substrate stage, without being affected by the specific oscillation of a projecting optical system being a reference for detecting the position of a substrate stage. SOLUTION: In this position detecting device, the position of a projecting optical system 4 is detected (15), and the position of a substrate stage 6 is detected (16), and the specific oscillation frequency components of the projecting optical system 4 are removed by a correcting part 19 which is a low-pass filter, and the substrate stage 6 is controlled by a servo arithmetic part 20, drive amplifier 21, and control part 17. Thus, a servo loop for controlling the driving of the substrate stage 6 can be prevented from being affected by the specific oscillating frequencies of the projecting optical system 4, and even when the control performance of the servo is increased, oscillation by the specific oscillating frequencies can be prevented. Therefore, the substrate stage 6 can be quickly controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting device for detecting the position of a movable stage, and more particularly to a stage of an exposure device used for manufacturing, for example, a liquid crystal display element, a semiconductor element, a thin film magnetic head, and the like. TECHNICAL FIELD The present invention relates to a position detection device suitable for application to the like and an exposure apparatus using the position detection device.

[0002]

2. Description of the Related Art For example, in order to manufacture a large-sized liquid crystal panel (liquid crystal display substrate) or a large-area semiconductor device at a high throughput, a mask (photomask or reticle, etc.) is used.
The upper slit-shaped (rectangular, arc-shaped, etc.) illumination area is illuminated, the mask is scanned in the short side direction with respect to the illumination area, and photoresist is applied to an exposure area conjugate to the illumination area. Attention has been paid to a scanning exposure apparatus that sequentially exposes a pattern on a mask onto a plate by synchronously scanning a substrate (such as a glass plate or a semiconductor wafer).

FIG. 2 shows an example of such a scanning type exposure apparatus, in which an illumination optical system 1 and a projection optical system 4 include a base 1.
The base 10 is fixed to the base 10 by a B column 8 integrated with the reference numeral 0. The mask 2 is placed on a scanning carriage 7 movably arranged with respect to the base 10 via a mask stage 3 which can be moved by a small amount with respect to the carriage 7. The substrate 5 is placed via a substrate stage 6 that can be moved by a minute amount (the fixed part is drawn with a thick line, and the movable part is drawn with a thin line). The scanning optical system 4 is scanned by scanning the carriage 7.
Scans the mask 2 and the substrate 5 in a predetermined direction with respect to
The pattern of the mask 2 is sequentially transferred onto the substrate 5. The laser interferometer 22 is supported by the A column 9, and interferes with a light beam reflected from the fixed mirror 11 provided on the projection optical system 4 and a light beam reflected from the movable mirror 12 provided on the substrate stage 6. The position of the substrate stage 6 with respect to the projection optical system 4 as a reference unit is detected. Main controller 40 acquires the position information of substrate stage 6 from laser interferometer 22. Main controller 40 includes an acceleration / deceleration calculation unit 18 that outputs an acceleration / deceleration command according to an exposure program, and a servo that calculates and outputs a drive signal for carriage 7 based on the difference between the acceleration / deceleration command and the position information of substrate stage 6. An arithmetic unit 20 and a drive amplifier 21 for amplifying the output of the servo arithmetic unit 20 are provided. The control unit 17 controls the drive of the carriage 7 by the output of the drive amplifier 21. These laser interferometer 22 and main controller 4
The control unit 17 and the control unit 17 form a servo loop, and perform tracking control of the carriage 7 and the substrate stage 6 based on the acceleration / deceleration command output from the acceleration / deceleration calculation unit 18 and the position information of the substrate stage 6.

[0004]

However, under the influence of the movement of the carriage 7 or the vibration of other devices, the B column 8 may vibrate at its own vibration frequency, for example, 50 Hz. For this reason, the control band of the servo loop can only take at most 1/3 of it, that is, about 10 Hz. Therefore, this becomes a bottleneck and cannot improve the control performance of the servo loop. The present invention has been made in view of the above problems, and has provided a position detection device capable of improving the control performance of a stage without being affected by vibration of a reference portion for detecting a position of a stage, and using the position detection device. An object of the present invention is to provide an exposure apparatus.

[0005]

Means for Solving the Problems In order to solve the above problems, the position detecting device according to the present invention will be described with reference to FIG. 1 showing an embodiment of the present invention.
The position of the stage is detected by interference between a light beam reflected by a fixed mirror (11) disposed on the movable stage and a light beam reflected by a movable mirror (12) disposed on a movable stage (6). A correcting unit (19) for correcting an error caused by the vibration of the fixed mirror (11); and a correcting unit (1).
Control means (17) for controlling the stage (6) based on the output of (9).

According to a second aspect of the present invention, in the position detecting device, since the correction means (19) is a low-pass filter, the stage control servo loop can be used with a simple configuration to provide the reference section (7).
The effects of vibration can be eliminated. Further, in the position detecting device according to the third aspect, since the correction means (19) corrects the error based on a stage command signal for commanding driving of the stage (6), the position detecting device is based on the stage command signal. The stage (6) can be controlled by predicting the vibration of the reference portion (7), and a high-speed response can be achieved.

According to a fourth aspect of the present invention, there is provided an exposure apparatus for exposing a pattern of a mask (2) to a substrate (5), wherein the mask (2) is placed on a mask stage (3).
A substrate stage (6) on which the substrate (5) is placed;
The position detecting device is used as a position detecting device for detecting a position of at least one of the mask stage (3) and the substrate stage (6). In the exposure apparatus according to the fifth aspect, the image of the pattern is projected onto the substrate (5) by a projection optical system (4), and the fixed mirror (11) is disposed on the projection optical system (4). Therefore, the position of the stage can be controlled with reference to the projection optical system (4).

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is an overall schematic side view of a scanning exposure apparatus according to the present embodiment. The illumination optical system 1 is fixed to the base 10 by a B column 8 integrated with the base 10 and includes a light source, a light guide, a fly-eye lens, a field stop, a condenser lens, and the like. The emitted illumination light illuminates the illumination area on the mask 2 with a uniform illuminance distribution. The mask 2 is held via a mask stage 3 above a carriage 7 having a U-shaped cross section. The mask stage 3 is supported movably on the upper surface of the carriage 7. The mask 2 is finely moved with respect to the carriage 7 integrally with the mask stage 3. A substrate 5, which is a rectangular glass plate coated with a photoresist, is held under the carriage 7 via a substrate stage 6, and the substrate stage 6 is supported on the lower surface of the carriage 7 so as to be finely movable. . The carriage 7 is mounted on the base 1 by an air bearing or an electromagnetic bearing which is a non-contact type bearing.
It is supported so as to be movable above zero and moves in the X direction in FIG. In the present embodiment, the carriage 7 is driven by a linear motor. A projection optical system 4 for projecting an erect erect image at the same magnification between the mask 2 and the substrate 5 is fixed to the base 10 by a B column 8 (fixed portions are drawn with thick lines, and movable portions are drawn with thin lines). There). For this reason,
A pattern (for example, a liquid crystal display element pattern) on the mask 2 is exposed on the substrate 5 through the projection optical system 4 as an equal-sized erect image. Then, by driving the carriage 7 in the X direction to scan the mask 2 and the substrate 5 integrally,
The pattern on the mask 2 is sequentially exposed on the substrate 5. The laser interferometer 15 is supported by the A column 9 and the projection optical system 4
Reflected by fixed mirror 11 and A column 9
The position of the projection optical system 4 with respect to the A column 9 is detected by interference with the light beam reflected from the fixed mirror 13 disposed in the.
The laser interferometer 16 is supported by the A column 9, and is caused by interference between the light beam reflected from the movable mirror 12 provided on the substrate stage 6 and the light beam reflected from the fixed mirror 14 provided on the A column 9. The position of the substrate stage 6 based on 9 references is detected. Position information of the projection optical system 4 based on the A column 9 from the laser interferometer 15 and the laser interferometer 16 based on the A column 9
Main controller 30 captures the position information of substrate stage 6 from the above. The B column 8 vibrates at a natural vibration frequency (for example, 50 Hz) due to the movement of the carriage 7, and the positions of the projection optical system 4 and the fixed mirror 11 fixed to the projection optical system 4 are shifted due to the bending vibration of the B column 8. Would. Therefore, main controller 30 includes acceleration / deceleration calculation unit 18 that outputs an acceleration / deceleration command in accordance with an exposure program and projection optical system 4.
A correction unit 19 that outputs corrected position information of the projection optical system 4 based on the position information and the acceleration / deceleration command, and the carriage 7 based on the acceleration / deceleration command, the output of the correction unit 19, and the position information of the substrate stage 6. And a drive amplifier 21 for amplifying the output of the servo calculation unit 20. The correction unit 19 is composed of a CPU and corrects the position information of the projection optical system 4 based on the A column 9 according to the following equation.

[0009]

(Equation 1)

In the correction unit 19 for correcting the position information of the projection optical system 4, equation (1) is a low-pass filter that uses f ₁ as a cutoff frequency for the position x ₁ (t) of the projection optical system 4. For example, when the natural vibration frequency of the B column 8 is 5
When the frequency is 0 Hz, the cutoff frequency f ₁ is set to 17 Hz, and the vibration component at 50 Hz is removed. Thus, even if the B column 8 has its natural vibration frequency of 5
Vibration at 0 Hz does not affect the servo loop. Therefore, even if the servo control performance is improved, B
Oscillation does not occur at the natural vibration frequency of the column 8 of 50 Hz. Although the servo loop does not follow the natural vibration of the B column 8, the mask 2 and the substrate 5 are scanned integrally with the projection optical system 4, so that the exposure amount is substantially uniform. Scanning at a constant speed.
The positioning of the projection optical system 4 with respect to the mask 2 and the substrate 5 does not require high precision at high frequencies. That is, even if the position of the projection optical system 4 with respect to the mask 2 and the substrate 5 oscillates at a high frequency, the positions are averaged during the scanning process, and the exposure result is not affected.

Equation (2) represents the flexural vibration of the B column 8, and equation (3) represents the inverse function of the flexural vibration of the B column 8. Therefore, equation (4) represents the inverse system of flexural vibration of the B column 8 expected for acceleration-deceleration command x ₂ (t), B column 8 for acceleration-deceleration command x ₂ (t) The term
, And responds at a high speed in feedforward by predicting the bending vibration.

The output of the correction unit 19 is a weighted average of the above two equations as shown in equation (5), and is not affected by the natural vibration frequency of the B column 8 and the acceleration / deceleration command x
It responds at high speed by feedforward from ₂ (t). Note that the present invention is not limited to the above embodiment. The correction unit 19 calculates a ₂
= 0 and a pure low-pass filter or a band rejection filter instead of the low-pass filter. further,
By setting a ₁ = 0, the deflection vibration may be predicted based on the acceleration / deceleration command.

The control unit 17 controls the driving of the carriage 7 based on the output of the driving amplifier 21. These laser interferometers 1
6. The main control device 30 and the control unit 17 form a servo loop, and the acceleration / deceleration command output from the acceleration / deceleration calculation unit 18
The carriage 7 and the substrate stage 6 are controlled to follow based on the position information of the projection optical system 4 and the position information of the substrate stage 6 based on the column 9.

In the above configuration, first, in order to align the mask 2 with the substrate 5, the mask stage 3 is moved to move the mask-side alignment pattern formed on the mask 2 and the substrate-side alignment pattern formed on the substrate 5. Match the pattern. Then, the carriage 7 is moved by scanning at a constant speed. As a result, the entire pattern area on the mask 2 is transferred onto the substrate 5 and printing is completed. The control unit 17 may directly control the driving of the substrate stage 6 in addition to controlling the driving of the carriage 7. The servo operation unit 20 may be one that actually performs the operation, or one that stores a table of the output corresponding to the input in a memory in advance and refers to the table.

The stage for detecting the position may be the mask stage 3 on which the mask 2 is mounted, of the exposure apparatus, or the substrate 5.
May be the substrate stage 6 on which the substrate is mounted. Fixed mirror 11
Is provided outside the projection optical system 4 and the illumination optical system 1
Or A column 9, B column 8, etc. As the exposure apparatus, the mask 2 and the substrate 5 are exposed in a stationary state, and the step and repeat type exposure apparatus that sequentially moves the substrate 5 stepwise also exposes the mask 2 and the substrate 5 in close contact. The present invention can also be applied to a proximity type exposure apparatus. In these, the acceleration / deceleration command includes everything for driving the stage, such as for stepping or fine movement for positioning.

The linear motor for driving the carriage 7 is
It is composed of a moving element (for example, a coil) and a stator (for example, a permanent magnet). If this stator is provided on a frame that is vibrationally insulated from the base 10, the carriage 7
Is transmitted to the frame, and is less likely to be transmitted to the base 10. Therefore, the base 10
Vibration can be reduced. The scanning exposure apparatus according to the present embodiment performs optical adjustment of an illumination optical system 1 having a plurality of lenses and a projection optical system 4, and attaches a mask stage 3 and a substrate stage 6 composed of many mechanical parts to a carriage 7. It can be manufactured by connecting the main controller 30 and performing comprehensive adjustment (electrical adjustment, operation confirmation, etc.).

As exposure light, a KrF excimer laser (248 nm) and an ArF excimer laser (193n) are used.
m), not only the F ₂ laser (157 nm) only, it is possible to use a charged particle beam such as X-ray or electron beam. For example,
When an electron beam is used, thermionic emission type lanthanum hexaborite (LaB ₆ ), tantalum (Ta) is used as an electron gun.
Can be used.

The magnification of the projection optical system 4 may be any of a reduction system, an equal magnification and an enlargement system. Further, as the projection optical system 4,
When an excimer laser is used, quartz or fluorite is used as a glass material. When an X-ray is used, a catadioptric optical system is used (a reflective type mask is used). When an electron beam is used, an optical system is used. An electro-optical system including an electron lens and a deflector may be used as the system. The optical path through which the electron beam passes is evacuated.

[0019]

As described above, according to the present invention, the control performance of the stage is improved by eliminating the influence of the vibration of the reference portion for detecting the position of the stage from the servo loop for controlling the movable stage. The stage can be controlled at high speed.

[Brief description of the drawings]

FIG. 1 is an overall schematic side view of a scanning exposure apparatus of the present embodiment.

FIG. 2 is a schematic view showing an example of a conventional scanning exposure apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Illumination optical system 2 Mask 3 Mask stage 4 Projection optical system 5 Substrate 6 Substrate stage 7 Carriage 8 A column 9 B column 10 Base 11, 13, 14 Fixed mirror 12 Moving mirror

Claims (5)

[Claims] 1. A position detecting device for detecting a position of a stage based on a light beam reflected by a fixed mirror disposed on a reference portion and a light beam reflected by a movable mirror disposed on a movable stage. A position detection device comprising: a correction unit that corrects an error caused by vibration of the fixed mirror; and a control unit that controls the stage based on an output of the correction unit. 2. The position detecting device according to claim 1, wherein said correction means is a low-pass filter. 3. The position detecting device according to claim 1, wherein the correction means corrects the error based on a stage command signal for commanding the driving of the stage. 4. An exposure apparatus for exposing a pattern of a mask onto a substrate, wherein: a mask stage on which the mask is mounted; a substrate stage on which the substrate is mounted; and at least one stage of the mask stage and the substrate stage An exposure apparatus using the position detection device according to any one of claims 1 to 3 as a position detection device that detects the position of the exposure light. 5. The exposure apparatus according to claim 4, wherein the image of the pattern is projected onto the substrate by a projection optical system, and the fixed mirror is provided in the projection optical system. .