CN107436539B

CN107436539B - Exposure apparatus and method for manufacturing article

Info

Publication number: CN107436539B
Application number: CN201710375971.8A
Authority: CN
Inventors: 大野文靖
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 2016-05-25
Filing date: 2017-05-25
Publication date: 2023-09-22
Anticipated expiration: 2037-05-25
Also published as: CN107436539A; KR102169893B1; JP6748482B2; KR20170133275A; JP2017211493A

Abstract

The present invention relates to an exposure apparatus and a method for manufacturing an article. An exposure apparatus for performing scanning exposure of a substrate includes: a projection optical system that projects a pattern of an original plate onto the substrate; and a control unit. The projection optical system includes: a plurality of optical components including a concave mirror and a convex mirror; a plurality of adjustment units for applying forces to a plurality of portions on the back surface of the concave mirror in order to adjust the surface shape of the concave mirror; and a measuring unit that measures at least one of a position and a posture of the optical member. The control unit controls the plurality of adjustment units so that the surface shape of the concave mirror is adjusted during the execution of the scanning exposure, based on the measurement result measured by the measurement unit.

Description

Exposure apparatus and method for manufacturing article

Technical Field

The present invention relates to an exposure apparatus and a method for manufacturing an article.

Background

Liquid crystal display panels are increasingly used as display devices such as FPDs (flat panel displays). The liquid crystal display panel is manufactured by a photolithography method using an exposure device. In recent years, an exposure apparatus is required to have high precision, and aberration correction of a projection optical system is required. For example, a technique of correcting aberration by deforming the surface shape of a mirror has been proposed (see patent document 1 and patent document 2).

Patent document 1: japanese patent laid-open No. 2004-056125

Patent document 2: japanese patent laid-open No. 2006-128699

Disclosure of Invention

However, in the technique of patent document 1, since the surface shape is determined so as to measure the aberration of the projection optical system and correct the measured aberration, a large amount of measurement time is required, which is disadvantageous in terms of working efficiency. In addition, in the technique of patent document 2, in order to correct a deviation due to unevenness in the surface shape of an optical element, which is a characteristic of an optical system, a deformable reflective device is used. However, with the development of the miniaturization of devices, even in an exposure apparatus using a projection optical system in which unevenness of the surface shape of an optical element is sufficiently adjusted, it is necessary to correct a change in optical performance due to displacement of an optical member during exposure.

The present invention provides a technique that facilitates the realization of both working efficiency and imaging performance.

According to one aspect of the present invention, there is provided an exposure apparatus for performing scanning exposure of a substrate, the exposure apparatus comprising: a projection optical system that projects a pattern of an original plate onto the substrate; and a control unit, wherein the projection optical system includes: a plurality of optical components including a concave mirror and a convex mirror; a plurality of adjustment units for applying forces to a plurality of portions on the back surface of the concave mirror in order to adjust the shape of the surface of the concave mirror; and a measuring unit that measures at least one of a position and a posture of the optical member, wherein the control unit controls the plurality of adjusting units so that a surface shape of the concave mirror is adjusted during execution of the scanning exposure, based on a measurement result measured by the measuring unit.

According to another aspect of the present invention, there is provided a method of manufacturing an article, the method comprising: step 1, exposing a substrate by using an exposure device; and a 2 nd step of developing the substrate exposed in the 1 st step, wherein the manufacturing method manufactures an article based on the substrate developed in the 2 nd step, and wherein the exposure apparatus is an exposure apparatus that performs scanning exposure of the substrate, and comprises: a projection optical system that projects a pattern of an original plate onto the substrate; and a control unit, wherein the projection optical system includes: a plurality of optical components including a concave mirror and a convex mirror; a plurality of adjustment units for applying forces to a plurality of portions on the back surface of the concave mirror in order to adjust the shape of the surface of the concave mirror; and a measuring unit that measures at least one of a position and a posture of the optical member, wherein the control unit controls the plurality of adjusting units so that a surface shape of the concave mirror is adjusted during execution of the scanning exposure, based on a measurement result measured by the measuring unit.

According to the present invention, a technique advantageous for achieving both of the working efficiency and the imaging performance can be provided.

Other features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings. In the drawings, the same or similar structures are denoted by the same reference numerals.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention.

Fig. 1 is a schematic configuration diagram of an exposure apparatus according to an embodiment.

Fig. 2 is a diagram showing an example of the shape of a slit included in the illumination optical system according to the embodiment.

Fig. 3 is a diagram showing an example of a pattern on a mask.

Fig. 4 is a diagram showing an example of a pattern on a mask.

Fig. 5 is a diagram showing a characteristic example of astigmatism.

Fig. 6 is a flowchart of the correction processing of the concave mirror in the embodiment.

Fig. 7 is a diagram showing an example of a supporting structure of the convex mirror.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the following embodiments, but the following embodiments merely represent specific examples of the practice of the present invention. All combinations of features described in the following embodiments are not necessarily required to solve the problems of the present invention.

Fig. 1 is a schematic configuration diagram of an exposure apparatus according to an embodiment. The exposure apparatus of the present embodiment includes an illumination optical system IL. The illumination optical system IL has a light source, and can select the light source optimal for the manufactured device from an excimer laser, a high-pressure mercury lamp, and the like. For example, a high-pressure mercury lamp is used in manufacturing a liquid crystal display element, and g-line (436 nm), h-line (405 nm), and i-line (365 nm) can be used.

The mask 1 as a master is, for example, a circuit pattern necessary for manufacturing a liquid crystal display element. The mask 1 is mounted on a mask stage 2. The mask 1 is irradiated with the exposure light from the illumination optical system IL. The exposed light transmitted through the mask 1 passes through the projection optical system PO to image an image of the mask 1 on the substrate 3.

The substrate 3 is mounted on the substrate stage 4, and the mask stage 2 and the substrate stage 4 are scanned in synchronization, so that a large area can be exposed. The substrate 3 is coated with a photosensitive material having sensitivity to exposure light, and a pattern can be formed on the substrate through a development process. The projection optical system PO includes a pair of concave mirrors 5 and a convex mirror 6. The exposed light from the mask 1 is reflected by the concave mirror 5, reflected by the convex mirror 6, and then reflected again by the concave mirror 5, so that an image of the mask 1 is imaged on the substrate 3. The projection optical system PO may further include a refractive member 9, and the refractive member 9 refracts the exposure light for aberration correction. The refractive member 9 includes, for example, a parallel plate, and by tilting the parallel plate with respect to the optical axis, correction of coma aberration, astigmatism, and distortion aberration can be performed. The concave mirror 5 may be integral or divided.

The arc-shaped image range outside the axis of the projection optical system PO including the concave mirror 5 and the convex mirror 6 shown in fig. 1 can be used for exposure. In order to illuminate the arc-shaped image range, the illumination optical system IL includes a slit 11 having an arc-shaped opening as shown in fig. 2.

As a coordinate system of the present exposure apparatus, a Z axis is taken from the substrate 3 toward the mask 1, a Y axis is taken from the convex mirror 6 toward the concave mirror 5, and an X axis is taken so as to form a right-hand coordinate system. In addition, the rotation direction around the X axis, which is the forward rotation direction in which the right-handed screw advances, is taken as ωx. The same definition applies to ωy and ωz about the Y axis and about the Z axis, respectively.

The projection optical system PO includes a plurality of adjustment units 7 (driving mechanisms), and the plurality of adjustment units 7 apply forces to a plurality of portions on the rear surface of the concave mirror 5 in order to adjust the surface shape of the concave mirror. Any element such as a piezoelectric element can be used for the adjustment unit 7. By driving the plurality of adjustment portions 7, the shape of the reflecting surface of the concave mirror 5 can be changed. When the surface shape is deformed, the optical performance of the projection optical system PO changes in accordance with the shape thereof. Therefore, by controlling the plurality of adjustment portions 7, the optical performance of the projection optical system PO can be controlled.

The projection optical system PO includes a measurement unit 8, and the measurement unit 8 is configured to measure at least one of the position and the posture of the convex mirror 6. For example, the measuring unit 8 may be constituted by a length measuring machine using a laser. The length measuring machine can measure at least one of the position (X, Y, Z) and the posture (ωx, ωy, ωz) by selecting the optimal arrangement and number. The measuring unit 8 shown in fig. 1 measures the position and orientation of the convex mirror 6, but the optical member to be measured may be at least one of a plurality of optical members including the concave mirror 5 and the refractive member 9, in addition to the convex mirror 6. In addition, by using a plurality of measuring units, the position and orientation of a plurality of optical members can be measured at the same time.

The measuring unit 8 is connected to the control unit 10. The control unit 10 can acquire the measurement result from the measurement unit 8, and predicts a change in optical performance corresponding to a change in the position and orientation of the convex mirror 6 (hereinafter, simply referred to as "displacement"). Optical performance can include spherical aberration, curvature of field, astigmatism, coma, distortion aberration (aberrations), and the like, as well as the same shift in imaging position in the X, Y plane.

Fig. 3 and 4 show examples of patterns on the mask 1. As shown in fig. 3, a pattern long in the X direction is referred to as an H pattern, and a pattern long in the Y direction as shown in fig. 4 is referred to as a V pattern. When the projection optical system PO has astigmatism, the H pattern and the V pattern deviate in the imaging position (focus position) in the Z direction. The imaging performance is degraded due to the deviation of the focal position of the H pattern from the focal position of the V pattern due to the presence of astigmatism.

Due to the influence of disturbance from the floor on which the exposure device is installed, there is a possibility that each optical component in the projection optical system PO may deviate from its original position and orientation. For example, as shown in fig. 7, the convex mirror 6 is held by a holder 61, and the holder 61 is fixed to an inner wall of a chamber C constituting a housing of the projection optical system PO by a fixing member 63 via a shaft 62 which is a rod-like member extending in the lateral direction (X-axis direction). The direction in which the shaft 62 extends may be a longitudinal direction (Z-axis direction). Alternatively, the holder 61 may be fixed by a plurality of shafts extending in the lateral direction and the longitudinal direction (and further in other directions). In order to avoid the influence of disturbance in scanning exposure of the convex mirror 6, the support rigidity of the convex mirror 6 is required to be sufficiently high. However, since the periphery of the convex mirror 6 is the optical path of the exposure light, it is necessary to block the optical path by the shaft 62 to a minimum. Therefore, there is a limit in improving the rigidity of the shaft 62, and there is a high possibility that the position and orientation of the optical components in the projection optical system PO, particularly the convex mirror 6, are offset due to interference at the time of scanning exposure. When the position and orientation of the convex mirror 6 are shifted, the position and orientation of the convex mirror 6 itself may be restored, but it is difficult to arrange such a mechanism so as not to affect the optical path of the exposure light. Therefore, in the present embodiment, as described below, for example, the plurality of adjustment units 7 are controlled to change the surface shape of the concave mirror 5 so as to correct the change in optical characteristics associated with the change in the position and orientation of the convex mirror 6.

When the optical member such as the convex mirror 6 is displaced from its original position and orientation, the imaging performance changes in accordance with the displacement amount. For example, fig. 5 is a graph showing the difference between the imaging position (focus position) of the H pattern and the imaging position (focus position) of the V pattern when the convex mirror 6 is changed in the Y direction. The horizontal axis of fig. 5 represents the position in the X direction of the slit in fig. 2, and the vertical axis represents the difference (astigmatism) between the focus position of the H pattern and the focus position of the V pattern. In the present embodiment, the amount of change in astigmatism with respect to the change in the Y direction of the convex mirror 6 is shown, but any combination of displacement in the X direction and the Z direction, postures ωx, ωy, ωz of the optical member, other aberrations, and the like may be used.

In the embodiment, the prediction of the generation amount of astigmatism with respect to the displacement of the convex mirror 6 is performed as follows, for example. The amount of astigmatism generated for displacement was obtained by optical simulation in advance. The correspondence between the displacement and the amount of astigmatism is stored in the memory of the control unit 10 as a reference table, for example. The control unit 10 can predict the amount of generation of astigmatism corresponding to the measurement result of the measurement unit 8 as the amount of generation of astigmatism generated in the projection optical system PO based on the correspondence relation. Alternatively, the displacement of the convex mirror 6 may be measured by the measuring unit 8, and the amount of astigmatism generated may be calculated by performing optical simulation based on the measurement result.

Next, the control unit 10 determines the surface shape of the concave mirror 5 for correcting the predicted aberration. In the present embodiment, an example of correcting astigmatism is given, but a plane shape in which any aberration such as the coma aberration and the distortion aberration is taken into consideration can be calculated. In addition, a plane shape for correcting a plurality of aberrations can also be calculated. In order to deform the surface shape of the concave mirror 5 with the object of correcting the calculated surface shape of the aberration, the control unit 10 calculates the driving amounts of the plurality of adjustment units 7, respectively. The control unit 10 drives each adjustment unit according to the calculated drive amount. This allows the concave mirror 5 to be deformed into a desired shape, thereby correcting astigmatism associated with displacement of the convex mirror 6.

The correction can be performed, for example, as follows. First, during the step driving of the substrate stage 4 or during the replacement of the substrate during the non-exposure, the control unit 10 obtains the displacement of the convex mirror 6 from the measurement result of the measurement unit 8, and predicts the aberration generated by the displacement. Then, the control unit 10 determines the surface shape of the concave mirror 5 for correcting the aberration, and drives the plurality of adjustment units 7 to correct the aberration of the projection optical system PO.

As a specific example, the correction of astigmatism when the convex mirror 6 is changed in the Y direction is described above. As another example, when the posture of the convex mirror 6 is changed to +ωx, the imaging position is changed in the +y direction as a whole. For example, when the convex mirror 6 vibrates in the ±ωx direction due to disturbance during scanning exposure, the imaging position on the substrate 3 vibrates in the ±y direction. The imaging performance is degraded due to the vibration of the imaging position during scanning exposure. To perform this correction, the posture ωx of the convex mirror 6 is measured at all times during the exposure, and the change in the imaging position due to the change in the posture ωx is predicted by the control unit 10. Based on the prediction, the surface shape of the concave mirror 5 for correcting the shift of the imaging position is calculated, and the plurality of adjustment units 7 are driven with the calculated surface shape as a target, thereby deforming the surface shape of the concave mirror 5. By performing these processes in real time, vibration of the image on the substrate 3 can be suppressed. As a result, a decrease in contrast can be prevented, and good imaging performance can be obtained.

The measurement by the measuring unit 8, the prediction of imaging performance (aberration), the calculation of the surface shape of the concave mirror, and the driving of the plurality of adjusting units can be performed not only during the execution of the scanning exposure but also at any timing when the scanning exposure is not executed. In addition, as described above, it is effective not only in terms of variation in aberration but also in terms of offset of the imaging position in the X, Y plane.

In the present embodiment, the displacement of the convex mirror 6 is described, but by providing a measuring section for measuring the displacement of the refractive member 9 and the concave mirror 5 provided with a driving mechanism, for example, the change in imaging performance due to the displacement and posture change of the refractive member 9 and the concave mirror 5 can be corrected by the same method. Further, it is also possible to measure displacement of the plurality of optical components such as the convex mirror 6, the refractive member 9, and the concave mirror 5, and predict how the imaging performance of the projection optical system PO changes due to the displacement of the plurality of optical components. The surface shape of the concave mirror 5 for correcting the change in imaging performance predicted by the displacement of the plurality of optical members in a lump may be calculated, and the driving amount of the plurality of adjustment units 7 may be calculated based on the calculated result to drive the plurality of adjustment units 7. Thus, variations in optical performance caused by the plurality of optical components can be corrected. As described above, the optical component to be measured and the aberration predicting the direction of displacement and the change can be arbitrarily combined selectively.

Fig. 6 is a flowchart of the correction processing of the concave mirror 5 by the control section 10. First, the control unit 10 measures the positions X, Y, Z and the postures ωx, ωy, ωz of the optical members included in the projection optical system PO based on the measurement data acquired from the measurement unit 8 (S1). Next, the control unit 10 predicts a change in optical performance (aberration) from the measured change in position and orientation (S2). The control unit 10 calculates the surface shape of the concave mirror 5, such as correcting the change in optical performance, based on the predicted change in optical performance (S3). Next, the control unit 10 calculates the driving amounts of the plurality of adjustment units 7 with the calculated surface shape as a target (S4). Then, the control unit 10 drives the plurality of adjustment units 7 in accordance with the calculated drive amount (S5). As described above, this correction process can be performed during execution of the scanning exposure. The correction process may be performed not only during the execution of the scanning exposure but also during the non-execution of the scanning exposure.

Next, a modification of the above embodiment will be described. The deformation of the substrate and the like can be measured before exposure, and the influence on the imaging performance due to the deformation of the substrate can be corrected by driving the driving mechanism based on the measurement result before exposure. However, it is difficult to measure the position of the optical member before exposure and to estimate the aberration from the result thereof, and to drive the driving mechanism to correct the optical performance, because the optical member included in the projection optical system always vibrates due to disturbance or the like. For example, information on the position of the optical member to be measured is fed back to the control unit 10 to control the plurality of adjustment units 7, but there is a possibility that a sufficient time for feedback control of the plurality of adjustment units 7 cannot be obtained due to the scanning speed and the vibration speed.

In the case of an exposure apparatus that performs scanning exposure, the average value of the performance changes of the projection optical system PO is represented as a change in imaging performance during a period in which one point on the mask 1 passes under the exposure light irradiated from the slit 11. Therefore, even if correction of all aberration variations during exposure is not performed, correction of the exposure result can be performed. For example, the control unit 10 acquires measurement results at each measurement point measured by the measurement unit 8 during a period in which one point of the mask 1 passes through a predetermined portion (for example, half of the exposure area) based on the scanning exposure. The control unit 10 calculates an average value of the acquired measurement values, predicts a change in aberration from the average value, and calculates a surface shape of the concave mirror that corrects the predicted change in aberration. Then, the control unit 10 controls each of the adjustment units so as to drive the plurality of adjustment units 7 with the calculated surface shape as a target, while one point of the mask 1 passes through the remaining portion (remaining half) of the exposure area other than the predetermined portion based on the scanning exposure. Thus, for example, the aberration variation amount of the first half can be corrected, and the degradation of the imaging performance can be suppressed. In the above example, the average value of the positions in the case of passing through the half exposure region is taken as an example, but the optimum amount may be calculated from the time required for driving and the correction accuracy.

< embodiment of method for producing article >

The method for manufacturing an article according to the embodiment of the present invention is suitable for manufacturing an article such as a micro device such as a semiconductor device or an element having a microstructure. The method for manufacturing an article according to the present embodiment includes a step of forming a latent image pattern on a photosensitive agent applied to a substrate using the exposure device (a step of exposing the substrate), and a step of developing the substrate on which the latent image pattern is formed in the step. Such a production method includes other known steps (oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, and the like). The method for manufacturing an article according to the present embodiment is advantageous in at least 1 of performance, quality, productivity, and production cost of the article as compared with the conventional method.

The present invention has been described in connection with the exemplary embodiments, but the present invention should be understood not to be limited to the disclosed exemplary embodiments. The following claims should be accorded the broadest interpretation so as to encompass all modifications and equivalent structures as well as functions.

Claims

1. An exposure apparatus that performs scanning exposure of a substrate, the exposure apparatus comprising:

a projection optical system that projects a pattern of an original plate onto the substrate; and

the control part is used for controlling the control part to control the control part,

the projection optical system includes:

a concave mirror;

a convex mirror fixed to a housing of the projection optical system via a member;

a plurality of adjustment units for applying forces to a plurality of portions on the back surface of the concave mirror in order to adjust the shape of the surface of the concave mirror; and

a measuring unit for measuring at least one of the position and the posture of the convex mirror,

the control section performs control of the plurality of adjustment sections during execution of the scanning exposure to correct aberration of the projection optical system generated during execution of the scanning exposure due to a change in at least one of a position and a posture of the convex mirror, to suppress vibration of an image exposed on the substrate, based on a measurement result measured by the measurement section during execution of the scanning exposure,

the measuring section performs measurement during a period when one point of the master passes through a prescribed portion of an exposure area based on the scanning exposure,

the control unit predicts an aberration of the projection optical system based on the measurement result, calculates a plane shape of the concave mirror for correcting the predicted aberration, and controls the plurality of adjustment units with the calculated plane shape as a target during a period in which the one point passes through a portion of the exposure region other than the predetermined portion based on the scanning exposure.

2. The exposure apparatus according to claim 1, wherein,

the aberration of the projection optical system due to a change in at least one of the position and the posture of the convex mirror is astigmatism.

3. The exposure apparatus according to claim 1, wherein,

the convex mirror is fixed via a rod-shaped member extending in a direction perpendicular to a direction from the substrate to the original plate and a direction from the convex mirror to the concave mirror.

4. The exposure apparatus according to claim 1, wherein,

the control unit predicts an aberration of the projection optical system based on a measurement result of the measurement unit, calculates a surface shape of the concave mirror for correcting the predicted aberration in real time, and controls the plurality of adjustment units with the calculated surface shape as a target.

5. The exposure apparatus according to claim 4, wherein,

the control unit predicts the aberration of the projection optical system based on a correspondence relationship between a change in at least one of a position and a posture of an optical member to be measured by the measuring unit, which is obtained in advance, and the aberration of the projection optical system.

6. The exposure apparatus according to claim 1, wherein,

the control unit further controls the plurality of adjustment units during non-execution of the scanning exposure.

7. The exposure apparatus according to claim 1, wherein,

the control unit stores a table indicating a correspondence relationship between a change amount of at least one of the position and the posture of the convex mirror and an aberration of the projection optical system.

8. The exposure apparatus according to claim 7, wherein,

the control unit predicts an aberration generated in the projection optical system based on the table.

9. A method of manufacturing an article, wherein the method of manufacturing an article comprises:

step 1, exposing a substrate by using an exposure device; and

a step 2 of developing the substrate exposed in the step 1,

the manufacturing method manufactures an article based on the substrate developed in the 2 nd step,

the exposure device is an exposure device for performing scanning exposure of the substrate, and comprises:

the projection optical system includes:

a concave mirror;