JP2010087310A - Exposure apparatus, and method of manufacturing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To permit the individual difference between two stages each holding a substrate, in relation to positional measurement by a laser interferometer. <P>SOLUTION: This exposure apparatus includes: a first stage for holding and moving a substrate; a second stage for holding and moving a substrate; a measurement station used for measuring the position of an alignment mark on the substrate held to one-side stage selected from the first stage and the second stage and including a first laser interferometer for measuring the position of the one-side stage; and an exposure station used for exposing the substrate held to the one-side stage based on the position measured by the measurement station and including a second laser interferometer for measuring the position of the one-side stage. At least either of the first laser interferometer and the second laser interferometer includes an adjustment means to adjust a relative positional relationship of measurement light and reference light in accordance with which position out of the position of the first stage and that of the second stage is measured. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exposure apparatus having a first stage that holds and moves a substrate, a second stage that holds and moves a substrate, a measurement station, and an exposure station.

  In general, in an exposure apparatus used for manufacturing a semiconductor device or the like as shown in FIG. 4, scanning exposure is repeated while stepping the substrate 5 such as a wafer or a glass substrate, so that a plurality of regions on the substrate 5 are formed. A step-and-scan type exposure apparatus that repeats exposure transfer is referred to as a scanner.

  This exposure apparatus has wafer stages 2 and 4 for moving and positioning wafers 5a and 5b at high speed, and a reticle stage 12 for moving and positioning reticle 12a at high speed, and has two wafer stages 2a and 4a and wafer stage. The position measurement accuracy and positioning accuracy of 2b and 4b and the reticle stage 12 are greatly related to performance such as image performance and overlay accuracy exposed on the wafers 5a and 5b. The exposure apparatus further includes an illumination unit 11 and a projection optical system 1, and the wafer stages 2 a and 4 a and the wafer stages 2 b and 4 b are mounted on the stage base plate 13.

  Wafer stages 2a and 4a and wafer stages 2b and 4b of the exposure apparatus are mounted on coarse movement stages 4a and 4b for performing high-speed scanning and steps and coarse movement stage 4 as shown in FIG. Position measurement is performed by a laser interferometer 3 that includes fine movement stages 2 a and 2 b that perform positioning, and is provided on a support member 7 that supports the projection optical system 1. Further, in order to measure the position of fine movement stages 2a and 2b in the Z direction, the emitted light is guided in the Z direction by an X mirror (not shown) and irradiated onto Z reference mirror 10 provided on support member 7.

  In the laser interferometers 3a and 3b, it is necessary to adjust the laser optical axis at the time of assembling the apparatus. However, when this optical axis adjustment is not sufficient, or when the angle of the X mirror changes, nonlinear errors occur. . In addition, when the optical axis is insufficiently adjusted or when the angle change of the X mirror is large, the superposition state of the measurement light and the reference light deteriorates, and a sufficient interference signal cannot be obtained, which may make measurement impossible.

  In this conventional exposure apparatus, information such as the posture, position, and shape of the wafers 5a and 5b is focused on the alignment marks provided on the wafers 5a and 5b, the two wafer stages 2a and 4a, and the wafer stages 2b and 4b. An alignment operation that is measured by the sensor or the alignment scope 6 is performed. Further, after this alignment operation, exposure is performed while correcting the posture and position of wafer stages 2a and 4a and wafer stages 2b and 4b using the measurement data. In this conventional exposure apparatus, not only the positioning accuracy of the wafer stages 2a and 4a and the wafer stages 2b and 4b but also high productivity, that is, throughput is required.

Therefore, the exposure apparatus shown in FIG. 4 proposed in Patent Document 1 has two wafer stages 2a and 4a and two wafer stages 2b and 4b, and each of the wafer stages 2a and 4a and the wafer stages 2b and 4b includes: Alignment and exposure are processed in parallel in the alignment area 20 and the exposure area 21, respectively, the alignment waiting time is omitted, and the throughput is improved.
JP 2005-353969 A

  However, there is always a machine difference between the two wafer stages 2a and 4a and the wafer stages 2b and 4b in the exposure apparatus shown in FIG. 4 proposed in Patent Document 1, and one of the wafer stages 2a. , 4a, the optical axis of the laser interferometer 3a is not necessarily in the best optical axis adjustment state in the other wafer stages 2b, 4b.

  Thus, by having a plurality of wafer stages 2a and 4a and wafer stages 2b and 4b, a difference in the mirrors provided in each of the wafer stages 2a and 4a and the wafer stages 2b and 4b is produced. After the exchange of 4a and wafer stages 2b and 4b, the optical axis of the laser interferometer 3a and the laser interferometer 3b is greatly deviated, and in the worst case, measurement may not be possible.

  As a means for solving this problem, the measurement error and the measurement range due to the deviation of the optical axis are expanded by increasing the beam diameter of the laser interferometers 3a and 3b. However, in this solution, it is necessary to change the optical components such as the stage mirror 9 and the beam splitter used for the routing that have been used with the conventional small beam diameter to those corresponding to the large beam diameter, which is expensive. Become.

Further, it is necessary to increase the area of the stage mirror by increasing the beam diameter, the weight of the wafer stages 2a, 4a and the wafer stages 2b, 4b is increased, the driving power is increased, and the positioning accuracy is deteriorated. Furthermore, another solution is to strictly control the component tolerances and adjust them after assembly in order to minimize machine differences, but the technical difficulty of processing is very high and manufacturing takes time. Therefore, the cost becomes very high.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an exposure apparatus capable of allowing a solid difference between two stages holding a substrate with respect to position measurement by a laser interferometer.

  An exposure apparatus of the present invention for solving the above-described problems is selected from a first stage that holds and moves a substrate, a second stage that moves while holding a substrate, and the first stage and the second stage A measurement station for measuring the position of the alignment mark on the substrate held on one of the stages, a measurement station including a first laser interferometer for measuring the position of the one stage, and measurement by the measurement station An exposure station including a second laser interferometer for measuring the position of the one stage, the exposure station exposing the substrate held on the one stage based on the set position. The at least one of the first laser interferometer and the second laser interferometer with respect to the first stage and the second laser interferometer. Of the two stages depending on whether to measure any position, including adjustment means for adjusting the relative positional relationship between the reference light and measurement light, and wherein the.

  The present invention is advantageous in that a solid difference between two stages holding a substrate can be allowed for position measurement by a laser interferometer.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
A first embodiment of the present invention will be described with reference to FIG. 1 and FIG. 2 of the AA sectional view of FIG.
The illumination unit 11 shapes exposure light from an exposure light source (not shown) and irradiates the reticle (mask) 12a, which is an original. The reticle stage 12 moves and scans a reticle 12a having an exposure pattern. The projection optical system 1 is an optical system that projects the exposure pattern of the reticle 12a on the wafers 5a and 5b, which are substrates, at a predetermined reduced exposure magnification ratio.

   The wafer stages 2a and 4a as the first stage move while holding the wafer 5a, and the wafer stages 2b and 4b as the second stage move while holding the wafer 5b, from the projection optical system 1 for each exposure. Positioning is performed by sequentially moving to the exposure position. A planar motor is used to drive the wafer stages 2a and 4a and the wafer stages 2b and 4b in this embodiment. The stage surface plate 13 is a surface plate that supports and guides the two wafer stages 2a and 4a and the wafer stages 2b and 4b in each of an exposure area 21 as an exposure station and an alignment area 20 as a measurement station.

  The alignment area 20 includes the reticle stage 12, the two wafer stages 2a and 4a, and the wafer stage 2b and 4b, and the alignment mark on the wafer 5b on the substrate held by the selected one of the wafer stages 2b and 4b. It is a measurement station that measures the position, and includes a first laser interferometer 3b that measures the position of one of the wafer stages 2b and 4b. The exposure area 21 is an exposure station that exposes the wafer 5a held on one wafer stage 2a, 4a based on the position measured in the alignment area 20, and measures the position of one wafer stage 2a, 4a. A second laser interferometer 3a is included.

  The alignment scope 6 measures the alignment marks on the wafers 5a and 5b and the alignment reference marks on the wafer stages 2a and 4a and the wafer stages 2b and 4b. It is the microscope which performs the alignment measurement between. The laser interferometers 3a and 3b are means for measuring the positions of the wafer stages 2a and 4a and the wafer stages 2b and 4b. The laser interferometers 3a and 3b are not shown in the figure, but each of the exposure area 21 and the alignment area 20 includes X, Y, Z and rotation of the wafer stages 2a and 4a and the wafer stages 2b and 4b, respectively. A plurality are arranged so as to measure positions and postures with six degrees of freedom.

  The wafer stages 2 a and 4 a and the wafer stages 2 b and 4 b move and position the wafers 5 a and 5 b and the reference mark at the measurement position of the alignment scope 6 in the alignment area 20. The reference marks are provided on the upper surfaces of the wafer stages 2a and 2b, and alignment and the like between the reticle 12a and the wafer stages 2b and 4b are performed by the alignment scope 6 using the stage reference marks. At the same time, in the exposure area 21, the wafer stages 2a and 4a perform an exposure operation to expose the exposure pattern of the reticle 12a on the wafer 5a. Thereafter, the wafer stages 2a and 4a in the exposure area 21 and the wafer stages 2b and 4b in the alignment area 20 are exchanged.

  Laser interferometers 3a and 3b measure wafer stages 2a and 4a in exposure area 21 and stage wafer stages 2b and 4b in alignment area 20, respectively. At least one of the first laser interferometer 3b and the second laser interferometer 3a includes a mirror 10 that is a reflective element that reflects measurement light. In some cases, glass that is a transmissive element is used instead of the mirror 10.

In addition, information such as the shape and tilt of the stage mirror 10 is measured in advance, and the mirror shape is corrected for the measurement results of the laser interferometers 3a and 3b. A control unit (not shown) calculates a command value based on the position information and performs control. In order to measure the Z positions of the wafer stages 2a and 4a and the wafer stages 2b and 4b, mirrors 9 having an angle of 45 degrees are arranged on the fine movement stages 2a and 2b. The measurement light from the laser interferometer 3 is bounced up in the Z direction by the mirror 9 and guided to the mirror 10 attached to the support member 7 that supports the projection optical system 1.
The mirror 10 is attached to the support member 7 via an actuator 14 composed of a piezo or a motor.

  The actuator 14 that is an adjusting means is related to at least one of the first laser interferometer 3b and the second laser interferometer 3 at any position of the reticle stage 12, the two wafer stages 2a and 4a, and the wafer stages 2b and 4b. The relative positional relationship between the measurement light and the reference light is adjusted according to whether the measurement is performed. When moving the mirror 10 and adjusting the inclination of the surface of the mirror 10, at least two actuators 14 are used. The measurement light reflected by the mirror 10 returns to the laser interferometers 3a and 3b, and the Z position information is obtained by the difference from the X position measurement information.

  Based on the posture information of the mirror 10 that has been measured in advance using the time during the replacement operation of the wafer stages 2a and 4a and the wafer stages 2b and 4b, the posture parameter of the mirror 10 in the alignment area 20 is changed to the exposure area. This is reflected in the posture parameters of the 21 mirror 10. For this reason, a control unit (not shown) instructs and drives the actuator 14 to change the posture of the mirror 10 in the alignment area 20 and the exposure area 21.

  The posture of the mirror 10 is measured by a sensor such as an encoder (not shown) or an interferometer, and fed back to the control of the actuator 14 to have the number of measurement axes as required. When measuring the tilt of the reflecting surface of the mirror 10, at least two points are measured. At this time, parameters including the shape of the mirror 10 are stored in the memory 14a, which is a storage unit, in the same four types as the number of combinations of the alignment area 20 and the exposure area 21 and the wafer stages 2a and 4a and the wafer stages 2b and 4b. . The actuator 14 serving as the adjusting means is an actuator corresponding to each of the reticle stage 12 and the two wafer stages 2a and 4a and the wafer stages 2b and 4b with respect to at least one of the first laser interferometer 3b and the second laser interferometer 3a. 14 includes a memory 14 a that is a storage unit that stores a target value for 14.

After the replacement operation of the wafer stages 2a and 4a and the wafer stages 2b and 4b is completed, the laser interferometers 3a and 3b measuring the positions of the fine movement stages 2a and 2b are reset.
Thereby, even if the wafer stages 2a, 4a and the wafer stages 2b, 4b are exchanged between different alignment areas 20 and exposure areas 21, the best optical axis adjustment state of the interferometer optical axis can be obtained each time. The measurement error of the laser interferometers 3a and 3b can be reduced. Further, a plurality of wafers can be obtained without deteriorating the positioning accuracy of the wafer stages 2a, 4a and the wafer stages 2b, 4b due to an increase in the weight of the movable part, which is caused by increasing the beam diameter of the laser interferometers 3a, 3b. By using the stages 2a and 4a and the wafer stages 2b and 4b, the productivity of the apparatus is improved.

  Furthermore, when the optical axis adjustment performance of the optical axes of the laser interferometers 3a and 3b is further improved, the actuator 14 can be driven so that the interference signal from the interference light detection unit becomes a predetermined level or more. In the present embodiment, the optical axis of the laser interferometers 3a and 3b is adjusted by driving the position of the mirror 10 by the actuator 14, but the incident light and outgoing light to the laser interferometers 3a and 3b are parallel plane plates. The same effect can be obtained by adjusting these with an actuator such as a motor using a wedge substrate. Of course, position detecting means such as the laser interferometers 3a and 3b may be mounted on movable objects such as the wafer stages 2a and 4a and the wafer stages 2b and 4b.

Next, Embodiment 2 of the present invention will be described with reference to FIG.
Although the configuration is the same as that of the first embodiment shown in FIGS. 1 and 2, the configuration for measuring the Z position of the wafer stages 2a and 4a and the wafer stages 2b and 4b is the light emitted from the laser interferometers 3a and 3b by the X mirror 8. Is drawn on the support member 7 and vertically incident on the wafer stages 2a and 4a and the wafer stages 2b and 4b.

  According to the present embodiment, when the plurality of wafer stages 2a, 4a and wafer stages 2b, 4b are exchanged, the attitude and position of the mirror 10 are controlled by the actuator 14, so that the laser interferometers 3a, 3b can be manufactured at low cost. Prevent errors in the optical axis. An actuator 14 for controlling the attitude or position of the mirror 10 is provided on the support portion of the target mirror of the laser interferometers 3a and 3b. When the plurality of wafer stages 2a and 4a and wafer stages 2b and 4b are replaced, an alignment area 20 and an exposure area 21 And the wafer stage 2a, 4a, and the wafer stage 2b, 4b are adjusted to adjust the posture and position of the mirror 10 to prevent errors in the optical axes of the laser interferometers 3a, 3b, thereby preventing measurement errors and measurement errors. To do. Productivity is improved without impairing the positioning accuracy of the wafer stages 2a and 4a and the wafer stages 2b and 4b and the overlay accuracy of the apparatus.

(Example of device manufacturing method)
A device (semiconductor integrated circuit element, liquid crystal display element, etc.) includes a step of exposing a substrate (wafer, glass plate, etc.) coated with a photosensitive agent using the exposure apparatus of any one of the embodiments described above, and the substrate The film is formed and manufactured through a process of developing the film and other known processes. Other well known processes include etching, resist stripping, dicing, bonding, packaging, and the like.

1 is an overall configuration diagram of an exposure apparatus according to Embodiment 1 of the present invention. It is the sectional view on the AA line of FIG. It is a partial block diagram of the exposure apparatus of Example 2 of the present invention. It is a whole block diagram of the exposure apparatus of a prior art example.

Explanation of symbols

1: projection optical systems 2a, 2b: fine movement stages 3a, 3b: laser interferometers 4a, 4b: coarse movement stages 5a, 5b: wafer 6: alignment scope 7: support member 8: X mirror 9: mirror 10: mirror 11: Illumination unit 12: reticle stage 13: stage surface 14: actuator 20: alignment area 21: exposure area

Claims (5)

A first stage that holds and moves the substrate;
A second stage that holds and moves the substrate;
A measurement station for measuring a position of an alignment mark on a substrate held by one of the first stage and the second stage, wherein the first laser interference measures the position of the one stage; A measuring station including a meter,
An exposure station that exposes the substrate held on the one stage based on the position measured by the measurement station, the exposure station including a second laser interferometer that measures the position of the one stage; An exposure apparatus comprising:
With respect to at least one of the first laser interferometer and the second laser interferometer, the relative positional relationship between the measurement light and the reference light is determined depending on which position of the first stage or the second stage is measured. An exposure apparatus comprising an adjusting means for adjusting. At least one of the first laser interferometer and the second laser interferometer includes a reflective element that reflects the measurement light,
The adjusting means includes an actuator that moves the reflective element,
The exposure apparatus according to claim 1, wherein: At least one of the first laser interferometer and the second laser interferometer includes a transmission element that reflects the measurement light,
The exposure apparatus according to claim 1, wherein the adjustment unit includes an actuator that moves the transmissive element.   The adjustment unit includes a storage unit that stores a target value for the actuator corresponding to each of the first stage and the second stage with respect to at least one of the first laser interferometer and the second laser interferometer. 4. An exposure apparatus according to claim 2 or 3, wherein A step of exposing the substrate using the exposure apparatus according to claim 1;
Developing the substrate exposed in the step;
A device manufacturing method comprising:

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