KR20170133275A - Exposure apparatus and method of manufacturing article - Google Patents

Abstract

An exposure device conducting radiation exposure to substrates has a projection optical system projecting disc-like patterns to the substrate and a control part. The projection optical system comprises: a plurality of optical members having a concave mirror and a convex mirror; a plurality of adjustment parts applying force to a plurality of sites on the other side of the concave mirror in an attempt to adjust a surface shape of the concave mirror; and a measurement part measuring at least one of posture and a position of the optical member. The control part controls the plurality of adjustment parts to adjust the surface shape of the concave mirror while carrying out the radiation exposure based on the outcome measured by the measurement part.

Description

EXPOSURE APPARATUS AND METHOD OF MANUFACTURING ARTICLE [0002]

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

A liquid crystal display panel has been widely used as a display device such as an FPD (flat panel display). The liquid crystal display panel is manufactured using a method of photolithography using an exposure apparatus. In recent years, there has been a demand for high precision of the exposure apparatus, and a need to correct aberrations of the projection optical system has arisen. For example, a technique of correcting aberration by deforming the surface shape of a reflector has been proposed (see Patent Document 1 and Patent Document 2).

Japanese Patent Application Laid-Open No. 2004-056125 Japanese Patent Application Laid-Open No. 2006-128699

However, in the technique of Patent Document 1, a considerable measurement time is required in order to measure the aberration of the projection optical system and determine the surface shape so as to correct the measured aberration, which is disadvantageous from the viewpoint of throughput. Further, in the technique of Patent Document 2, a deformable reflective device is used for correction of errors caused by nonuniformity of the surface shape of the optical element as the characteristic of the optical system. However, it is necessary to correct the change in the optical performance caused by the displacement of the optical member during the exposure, even with the exposure apparatus using the projection optical system sufficiently adjusted in consideration of the non-uniformity of the surface shape of the optical element have.

The present invention provides a technique advantageous for achieving both throughput and imaging performance.

According to an aspect of the present invention, there is provided an exposure apparatus for performing scan exposure of a substrate, comprising: a projection optical system for projecting a pattern of an original plate onto the substrate; and a control unit, wherein the projection optical system includes a concave mirror and a plurality of convex mirrors A plurality of adjusting portions for applying a force to a plurality of portions of the back surface of the concave mirror so as to adjust the surface shape of the concave mirror and a measuring portion for measuring at least one of a position and a posture of the optical member, The control unit controls the plurality of adjustment units to adjust the surface shape of the concave mirror during the execution of the scan exposure based on the measurement result measured by the measurement unit.

According to the present invention, there is provided a technique advantageous for achieving both throughput and imaging performance.

Other features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings. In the accompanying drawings, the same reference numerals are assigned to the same or similar components.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
1 is a schematic configuration view of an exposure apparatus in the embodiment;
2 is a view showing an example of a slit shape of the illumination optical system of the embodiment;
3 is a view showing an example of a pattern on a mask.
4 is a view showing an example of a pattern on a mask;
5 is a diagram showing an example of characteristics of astigmatism;
6 is a flowchart of a correction process of a concave mirror in the embodiment;
7 is a view showing an example of a support structure of a convex mirror.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments, and the following embodiments are merely illustrative of specific embodiments of the present invention. In addition, all of the combinations of the features described in the following embodiments are not necessarily essential for solving the problems of the present invention.

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

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

The substrate 3 is mounted on the substrate stage 4. The mask stage 2 and the substrate stage 4 are scanned in synchronization with each other so that a large area can be exposed. The substrate 3 is coated with a photosensitive material having sensitivity to exposure light, and it is possible to form a pattern on the substrate by carrying out a developing process. The projection optical system PO includes a pair of concave mirror 5 and convex mirror 6. The exposure light emerging from the mask 1 is reflected by the concave mirror 5 and reflected by the convex mirror 6 and again reflected by the concave mirror 5 to form an image of the mask 1 on the substrate 3 . The projection optical system PO may also include a refractive member 9 for refracting exposure light to correct aberrations. The refractive member 9 includes, for example, a parallel flat plate, and by tilting the parallel flat plate with respect to the optical axis, coma, astigmatism and distortion can be corrected. The concave mirror 5 may be integrally or divided.

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 a good image area in an off-axis arc shape. The illumination optical system IL includes a slit 11 having an arc-shaped opening as shown in Fig. 2 in order to illuminate a good image area of an arc shape.

As the coordinate system of the present exposure apparatus, the Z axis is taken in the direction from the substrate 3 toward the mask 1, the Y axis is taken in the direction from the convex mirror 6 to the concave mirror 5, and the X axis is taken to form the right- do. Also, take ωx in the direction of rotation in which the right-handed screw advances around the X-axis. ωy, and ωz are defined around the Y axis and around the Z axis, respectively.

The projection optical system PO has a plurality of adjusting portions 7 (driving mechanisms) for applying a force to a plurality of portions of the back surface of the concave mirror 5 to adjust the surface shape of the concave mirror 5. The adjustment section 7 can be any piezoelectric element or the like. It is possible to change the shape of the reflecting surface of the concave mirror 5 by driving the plurality of adjusting portions 7. If the surface shape is deformed, the optical performance of the projection optical system PO changes depending on the shape. Therefore, it is possible to control the optical performance of the projection optical system PO by controlling the plurality of adjustment portions 7. [

The projection optical system PO is provided with a measuring section 8 for measuring at least one of the position and the attitude of the convex mirror 6. The measuring section 8 can be constituted by, for example, a laser using a side organs. The supporting organ can measure at least one of the position (X, Y, Z) and the postures (? X,? Y,? Z) by selecting the optimum arrangement and number. The measurement unit 8 shown in Fig. 1 measures the position / posture of the convex mirror 6, but the optical member to be measured is not limited to the convex mirror 6, but the concave mirror 5, 9 may be used. It is also possible to simultaneously measure the positions and postures of a plurality of optical members by using a plurality of measuring units.

The measuring section 8 is connected to the control section 10. The control unit 10 can acquire the measurement result from the measuring unit 8 and predict a change in optical performance corresponding to a change in the position and posture of the convex mirror 6 (hereinafter simply referred to as " displacement " . The optical performance may include spherical aberration, curvature of field, astigmatism, coma aberration, distortion, and uniform deviations in the X, Y plane of the imaging position.

Figs. 3 and 4 show examples of patterns on the mask 1. Fig. As shown in Fig. 3, a long pattern in the X direction is referred to as an H pattern, and a long pattern in the Y direction as shown in Fig. 4 is referred to as a V pattern. If there is an astigmatism in the projection optical system PO, a difference occurs in the imaging position (focus position) in the Z direction between the H pattern and the V pattern. The existence of the astigmatism causes a difference in the focus positions of the H pattern and the V pattern, and the imaging performance deteriorates.

Each optical member in the projection optical system PO may deviate from its original position / posture owing to the influence of the disturbance from the floor where the exposure apparatus is installed. For example, the convex mirror 6 is held by a holder 61, as shown in Fig. 7, so that the holder 61 is a shaft-like member that extends in the lateral direction (X-axis direction) 62 and fixed to the inner wall of the chamber C constituting the housing of the projection optical system PO by the fixing member 63. [ The direction in which the shaft 62 extends may be the 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 (or the other direction), respectively. It is required that the supporting rigidity of the convex mirror 6 be sufficiently high in order that the convex mirror 6 is not affected by the disturbance at the time of scanning exposure. However, since the periphery of the convex mirror 6 is an optical path of the exposure light, it is necessary to minimize the optical path by the shaft 62. [ Therefore, there is a limit in increasing the rigidity of the shaft 62, and the position / posture of the convex mirror 6, particularly in the optical member in the projection optical system PO, is affected by the influence of disturbance at the time of scanning exposure There is a high possibility of deviation. When the position and posture of the convex mirror 6 are shifted, the position and posture of the convex mirror 6 itself can be returned to the original state. However, it is difficult to arrange such a mechanism so as not to interfere with the light path of the exposure light Do. Therefore, in the present embodiment, as described below, for example, by controlling the plurality of adjustment sections 7 so as to correct the change in the optical characteristic accompanying the change of the position and posture of the convex mirror 6, ) Will be changed.

If the optical member such as the convex mirror 6 deviates from the original position / posture, the image forming performance changes depending on the amount of deviation. For example, Fig. 5 is a graph showing the difference between the imaging position (focus position) of the H pattern and the V pattern when the convex mirror 6 changes in the Y direction. The horizontal axis in Fig. 5 shows the position in the X direction of the slit in Fig. 2, and the vertical axis shows the difference (focus point vehicle) between the focus positions of the H pattern and the V pattern. Although the amount of change of the astigmatism with respect to the change in the Y direction of the convex mirror 6 is shown in the present embodiment, any combination of the displacements in the X direction and the Z direction and the attitudes? X,? Y, And so on.

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

Next, the control section 10 determines the surface shape of the concave mirror 5 for correcting the predicted aberration. In the present embodiment, correction of astigmatism is taken as an example, but it is possible to calculate the surface shape in consideration of any aberration such as the coma aberration and the distortion aberration described above. It is also possible to calculate the surface shape for correcting a plurality of aberrations. The control section 10 calculates the drive amount of each of the plurality of adjustment sections 7 because the surface shape of the concave mirror 5 is deformed with the aim of the surface shape for correcting the calculated aberrations. The control unit (10) drives each adjustment unit with the calculated drive amount. As a result, the surface shape of the concave mirror 5 is deformed to a desired surface shape, and the astigmatism accompanying the displacement of the convex mirror 6 can be corrected.

The above correction can be made, for example, as follows. First, during the step drive of the substrate stage 4 during non-exposure, or during the replacement of the substrate, the control unit 10 obtains the displacement of the convex mirror 6 based on the measurement result of the measurement unit 8, . Thereafter, the control section 10 determines the surface shape of the concave mirror 5 to correct the aberration, and drives the plurality of adjustment sections 7 to correct the aberration of the projection optical system PO.

As described above, the astigmatism correction in the case where the convex mirror 6 changes in the Y direction has been described. As another example, when the posture of the convex mirror 6 changes by +? X, the imaging position changes in the + Y direction as a whole. For example, when the convex mirror 6 vibrates in the ± x direction by disturbance during the scanning exposure, the imaging position on the substrate 3 vibrates in the ± Y direction. The image forming position is vibrated during the scanning exposure, the contrast of the image is lowered and the image forming performance is lowered. The posture? X of the convex mirror 6 is always measured during the exposure and the control unit 10 predicts the change of the imaging position due to the change of the posture? X. Based on the prediction, the surface shape of the concave mirror 5 is calculated to correct the deviation of the imaging position, and a plurality of adjustment portions 7 are driven with the calculated surface shape as a target, Thereby deforming the surface shape. By performing such processing in real time, it becomes possible to suppress the vibration of the image on the substrate 3. As a result, it is possible to prevent deterioration of contrast and to obtain good imaging performance.

The above-described measurement, prediction of the imaging performance (aberration), calculation of the surface shape of the concave mirror, and driving of the plurality of adjustment sections can be performed not only during the execution of the scanning exposure, Timing. As described above, not only the change in the aberration but also the deviation in the X and Y plane of the imaging position is also effective.

The displacement of the convex mirror 6 has been described in the present embodiment. However, by providing the measuring section for measuring the displacement of the concave mirror 5 including the refraction member 9 and the driving mechanism, And the variation of the imaging performance caused by the displacement and the attitude change of the concave mirror 5 can be corrected by the same method. It is also possible to predict how the imaging performance of the projection optical system PO will change as a plurality of optical members are displaced by measuring displacements of the plurality of optical members of the convex mirror 6, the refraction member 9 and the concave mirror 5 It is also possible to do. The surface shape of the concave mirror 5 for correcting the change in the imaging performance predicted by displacement of the plurality of optical members is calculated and the driving amount of the plurality of adjusting portions 7 is calculated from the calculated result, The adjustment section 7 may be driven. This makes it possible to correct a change in optical performance caused by a plurality of optical members. As described above, it is possible to arbitrarily select and combine the optical member to be measured and the aberration for predicting the direction or change of the displacement.

6 is a flowchart of the correction process of the concave mirror 5 by the control unit 10. Fig. First, the control unit 10 measures the position X, Y, Z of the optical member included in the projection optical system PO and the postures? X,? Y,? Z based on the measurement data acquired from the measurement unit 8 ). Next, the control unit 10 predicts a change in the optical performance (aberration) from the change in the measured position / posture (S2). Based on the predicted change in optical performance, the control unit 10 calculates the surface shape of the concave mirror 5 for correcting the change in the optical performance (S3). Next, the control unit 10 calculates the drive amount of each of the plurality of adjustment units 7 with the aim of the calculated surface shape (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 processing can be performed during the execution of the scanning exposure. The correction processing 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 or the like can be measured before the exposure and the influence of the image forming performance due to the deformation of the substrate can be corrected by driving the driving mechanism based on the measurement result before exposure. However, the optical member included in the projection optical system always vibrates due to disturbance or the like, so that the position of the optical member or the like is measured before exposure, the aberration is predicted from the result, and the drive mechanism is driven to correct the optical performance It is difficult. For example, the position information of the optical member to be measured is fed back to the control unit 10 to control the plurality of adjustment units 7, but the plurality of adjustment units 7 may be controlled depending on the scanning speed and the speed of the vibration, It may not be possible to take a sufficient time for feedback control.

In the case of the exposure apparatus that performs the scanning exposure, the average value of the performance change of the projection optical system PO appears as a change in the imaging performance while a point on the mask 1 passes under the exposure light irradiated from the slit 11. Therefore, it is possible to correct exposure results without correcting all aberration changes during exposure. For example, the control unit 10 determines whether or not the position of the mask 1 to each of the measurement points to the measurement unit 8 while a point of the mask 1 passes through a predetermined portion (for example, a half region) And obtains the measurement result. The control unit 10 calculates an average value of the obtained measurement values, estimates a change in the aberration from the average value, and calculates the surface shape of the concave mirror for correcting the change in the predicted aberration. While the mask 1 passes through the remaining portion of the exposure area except for the predetermined portion (the remaining half) by the scanning exposure, the control unit 10 sets a plurality of And controls each of the adjustment units 7 to drive the adjustment unit 7 of the apparatus. As a result, for example, half of the first half of the aberration change is corrected, and it is possible to suppress the deterioration of the imaging performance. In the above example, the average value of the positions in the case of half-passing the exposure area is taken as an example, but an optimum amount may be calculated from the time required for driving and the correction accuracy.

≪ Embodiment of production method of article >

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

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all modifications and equivalents of construction and functionality.

Claims (10)

An exposure apparatus for performing scan exposure of a substrate,
A projection optical system for projecting a pattern of the original plate onto the substrate,
And a control unit,
The projection optical system includes:
A plurality of optical members including a concave mirror and a convex mirror,
A plurality of adjusting portions for applying a force to a plurality of portions of the back surface of the concave mirror so as to adjust the surface shape of the concave mirror;
And a measuring unit for measuring at least one of a position and an attitude of the optical member,
Wherein the control section performs control of the plurality of adjustment sections so as to adjust the surface shape of the concave mirror during the execution of the scan exposure based on a measurement result measured by the measurement section. The method according to claim 1,
Wherein the metrology section measures at least one of a position and a posture of the convex mirror. The method according to claim 1,
Wherein the convex mirror is fixed to the inner wall of the housing of the projection optical system via a rod-shaped member. The method according to claim 1,
Wherein,
Aberration is predicted based on the measurement result of the measurement unit,
Calculating a surface shape of the concave mirror for correcting the predicted aberration,
And controls the plurality of adjustment sections to target the calculated surface shape. 5. The method of claim 4,
Wherein the control unit predicts the aberration from a relationship between a displacement and an aberration of an optical member to be measured of the measurement unit that is obtained in advance. The method according to claim 1,
Wherein the control section controls the plurality of adjustment sections even during non-execution of the scan exposure. The method according to claim 1,
Wherein the plurality of optical members include a refraction member for refracting exposure light to correct aberrations. 8. The method of claim 7,
Wherein the metrology unit measures at least one of a position and a posture of the refractive member. The method according to claim 1,
The measurement section performs measurement while a point of the original plate passes through a predetermined portion of the exposure area by the scan exposure,
Wherein,
Predicts an aberration based on a result of the measurement,
Calculating a surface shape of the concave mirror for correcting the predicted aberration,
And controls the plurality of adjustment sections to target the calculated surface shape while the point passes the portion other than the predetermined portion of the exposure region by the scan exposure. A method of manufacturing an article,
A first step of exposing a substrate using an exposure apparatus,
And a second step of developing the exposed substrate in the first step,
The manufacturing method is characterized in that an article is manufactured from the substrate developed in the second step,
The exposure apparatus includes a projection optical system for projecting a pattern of an original onto a substrate, and a control unit,
The projection optical system includes:
A plurality of optical members including a concave mirror and a convex mirror,
A plurality of adjusting portions for applying a force to a plurality of portions of the back surface of the concave mirror so as to adjust the surface shape of the concave mirror;
And a measuring unit for measuring at least one of a position and an attitude of the optical member,
Wherein the control section performs control of the plurality of adjustment sections so as to adjust the surface shape of the concave mirror during the execution of the scan exposure based on the measurement result measured by the measurement section.

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