JP2016062921A - Exposure device and device manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exposure device capable of highly accurately performing alignment or calibration.SOLUTION: An exposure device comprises a measuring unit which measures imaging characteristics of a projection optical system. The measuring unit includes: a plate 15 having a first measurement pattern P arranged in a position in which a mask must be arranged; a second measurement pattern 9 arranged in a substrate stage; a plate movement mechanism 16 provided separately from a driving mechanism which moves a mask stage and a driving mechanism which moves the substrate stage and for moving the plate so that the first measurement pattern is arranged in a targeted image height position; and a detector 10 which detects light from the first measurement pattern P, the projection optical system, and the second measurement pattern 9. The measuring unit calculates the imaging characteristics from the detection results by the detector.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an exposure apparatus and a device manufacturing method that perform calibration such as alignment and focus with high accuracy.

  2. Description of the Related Art An exposure apparatus that projects a mask pattern onto a substrate when manufacturing a microdevice (semiconductor element, liquid crystal display element, etc.) in a photolithography process is used. In order to accurately transfer the mask pattern onto the photosensitive substrate, the exposure apparatus is required to perform alignment of the mask and the substrate and focus alignment (focus calibration) with high accuracy.

  As one of the alignment or focus calibration methods, there is a TTL (Through The Lens) method that measures the relative position of the substrate with respect to the mask or the focus position of the mask pattern via a projection optical system. FIG. 1 is a schematic view of an example of an exposure apparatus having a TTL focus calibration function. As shown in FIG. 1, the exposure light emitted from the illumination optical system 1 passes through the mask 2 on which the actual device pattern mounted on the mask stage 3 is depicted, and the light incident on the projection optical system 4 is incident on the substrate 5. To reach. The pattern surface of the mask 2 and the substrate 5 are in a conjugate positional relationship by the projection optical system 4. Therefore, the actual device pattern of the mask 2 is projected and transferred onto the substrate 5 via the projection optical system 4. The substrate 5 is mounted on the substrate stage 6.

  An example of focus calibration is shown below. In order to irradiate the measurement pattern arranged on the mask 2 (or the mask stage 3) with the illumination optical system 1, a command is issued from the main control unit 7 to the mask stage control unit 8, and an interferometer (not shown) is provided. The mask stage 3 is moved by using it. An example of the measurement pattern is shown in FIG. The measurement pattern includes a pattern portion having a predetermined line width and pitch through which light passes and a peripheral portion that blocks light. A command is issued from the main control unit 7 to the substrate stage control unit 11 so that the substrate side mark 9 on the substrate stage 6 is arranged corresponding to the measurement pattern on the mask 2 (or mask stage 3), and an interferometer (not shown) is provided. The substrate stage 6 is moved using, for example.

The substrate side mark 9 is a transmission pattern corresponding to the measurement pattern on the mask 2 (or mask stage 3). A detector 10 that detects the amount of exposure light that has passed through the substrate side mark 9 is disposed under the substrate side mark 9. The substrate stage 6 is finely driven in the optical axis direction (Z direction) of the projection optical system 4, and the coordinate position of Z ₀ at which the detected light amount is maximum is calculated by the processing unit 12. FIG. 3 shows the relationship between the detected light quantity and the coordinate position in the Z direction at this time. The position where the detected light quantity becomes maximum is when the measurement pattern of the mask 2 and the substrate side mark 9 are in a conjugate positional relationship, and the focal position is calculated by searching for the maximum value of the light quantity. The calculated focal position information is transmitted from the processing unit 12 to the main control unit 7, and a command is issued from the main control unit 7 to the substrate stage control unit 11, and the substrate stage 6 is driven in the Z direction by an amount corresponding to the deviation of the focal position. Thus, the focus position of the mask pattern can be adjusted to the substrate 5.

  For example, in Patent Document 1, the focal position is determined by illuminating a substrate-side mark, detecting reflected light of a projection image of the mask-side mark by a projection optical system, and detecting a change in light quantity through the projection optical system and two marks. A method for calculating and performing focus calibration is shown. In addition, the amount of light when the mask side mark is illuminated, the transmitted light that has passed through the projection optical system and the substrate side mark is received by the detector, and the substrate stage is driven in a plane perpendicular to the optical axis of the projection optical system A method for measuring the relative position of a mask and a substrate by detecting a change is also shown.

JP-A-4-348019

  In order to perform TTL alignment and calibration with high accuracy, it is required to be able to change the types of measurement points and measurement target marks in the effective area of the projection optical system in accordance with exposure conditions. In the method proposed in Patent Document 1 described above, since the substrate side mark is driven together with the substrate stage, measurement points in the effective area of the projection optical system can be arbitrarily set. Since the instruments are integrated, the types of marks to be measured are limited.

  Accordingly, an object of the present invention is to provide an exposure apparatus that performs alignment or calibration with high accuracy.

  The present invention relates to a mask stage that holds a mask, a substrate stage that holds a substrate, a projection optical system that projects the pattern of the mask onto the substrate, and a measurement unit that measures the imaging characteristics of the projection optical system And an exposure apparatus that exposes the substrate while driving the mask stage and the substrate stage in a scanning direction, wherein the measurement unit is configured to perform a first measurement disposed at a position where the mask is to be disposed. A plate having a pattern, a second measurement pattern disposed on the substrate stage, a drive mechanism for driving the mask stage, and a drive mechanism for driving the substrate stage are provided separately, and the first measurement pattern is a target. A plate moving mechanism for moving the plate so as to be arranged at an image height position, the first measurement pattern, the projection optical system, and the second measurement Includes a detector for detecting light from the turn, the said measurement unit, and obtains the imaging characteristics from the detection result by the detection unit.

  According to the present invention, it is possible to provide an exposure apparatus that performs alignment or calibration with high accuracy.

It is a figure which shows the conventional exposure apparatus with a focus calibration function of a TTL system. It is an example of the pattern for a measurement used for focus calibration. It is an example which calculates a focus position from detected light quantity. It is the schematic of the exposure apparatus of 1st Embodiment. It is an example of the plate of 1st Embodiment. It is a figure which shows the state of the exposure apparatus at the time of measurement of 1st Embodiment. It is the schematic of the exposure apparatus of 2nd Embodiment. It is a flowchart of the exposure method of 2nd Embodiment. It is an example of the exposure range of the X direction of 2nd Embodiment. It is an example of the measurement position of the X direction of 2nd Embodiment. It is a figure which shows the state of the exposure apparatus at the time of measurement of 2nd Embodiment. It is an example of the deviation | shift amount and correction amount of the focus position of 2nd Embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[First embodiment]
FIG. 4 is a schematic view of a scanning type exposure apparatus according to the present invention. In FIG. 4, the same members as those in FIG. FIG. 4A is a front view of the entire exposure apparatus, and FIG. 4B is a plan view showing details of the periphery of the mask stage 3. First, the form which performs scanning exposure is demonstrated. As shown in FIG. 4, the exposure light emitted from the illumination optical system 1 passes through a mask (reticle) 2 on which an actual device pattern mounted on the mask stage 3 is depicted, and enters the projection optical system 4. The photosensitive substrate (wafer) 5 is reached. The actual device pattern surface of the mask 2 and the substrate 5 are in a conjugate positional relationship by the projection optical system 4. Therefore, the actual device pattern of the mask 2 is projected and transferred onto the substrate 5 via the projection optical system 4. The substrate 5 is held on the substrate stage 6. The mask device 3 and the substrate stage 6 are synchronously scanned in the Y direction in FIG.

  Next, a form in which focus calibration is performed will be described. Input unit 13 for inputting an exposure condition (exposure area, illumination mode, mask pattern, etc.) for exposing an actual device pattern, and determination for determining a measurement condition (measurement position, pattern) from information input by input unit 13 Part 14 is configured. Various mask side marks (first measurement patterns) P made of line and space patterns having different line widths, pitches, directions and the like are drawn on the plate 15. The plate 15 is moved by the plate moving mechanism 16 so that the first measurement pattern is arranged at the image height position targeted by P. The plate moving mechanism 16 may move the plate by an actuator, or may move manually by providing a movable mechanism. As shown in FIG. 4B, a plurality of sets of the plate 15 and the plate moving mechanism 16 are arranged at intervals in the X direction. Although the exposure apparatus of this embodiment has a plurality of sets of the plate 15 and the plate moving mechanism 16, the number of sets and the arrangement position of the sets are not limited.

  FIG. 5 shows an example of the plate 15. Although four types of first measurement patterns P1 to P4 having different pattern directions are drawn on the plate 15 in FIG. 5, the number and types of the first measurement patterns are not limited. The plate moving mechanism 16 is controlled by a plate moving mechanism control unit 17 and can move the plate 15 in a plane (XY plane) perpendicular to the optical axis (Z axis) of the projection optical system 4. Therefore, the plate 15 can be moved to any image height position within the effective area of the projection optical system 4 both in the scanning direction and in the orthogonal direction. The plate moving mechanism 16 in FIG. 4 is provided at an interval apart from the mechanism for driving the mask stage 3. However, the plate moving mechanism 16 may be mounted on the mask stage 3. A command is issued from the main control unit 7 to the mask stage control unit 8, and the mask stage 3 is retracted to a position where the mask 2 and the plate 15 do not interfere with each other.

  Thereafter, a command is issued from the main control unit 7 to the plate moving mechanism control unit 17 and the substrate stage control unit 11, and the plate moving mechanism 16 and the substrate stage 6 are set to the image height position (measurement position) and pattern determined by the determination unit 14. Move each one. In the present embodiment, the substrate side mark 9 is moved by the substrate stage 6, but it is also possible to configure a drive mechanism different from the substrate stage 6 to move the substrate side mark (second measurement pattern) 9. A detector 10 that detects the amount of exposure light that has passed through the substrate side mark 9 is disposed under the substrate side mark 9. The plate 15, the substrate-side mark (second measurement pattern) 9, the detector 10, and the plate driving mechanism 16 constitute a measurement unit that measures the imaging characteristics of the projection optical system 4 from the detection result by the detector 10. The imaging characteristic of the projection optical system 4 to be measured is a focus position or distortion. The measuring unit may be of a type that detects not only the amount of transmitted light but also the reflected light from the mark.

FIG. 6 shows a state of the exposure apparatus at the time of measurement in which the plate 15 and the substrate side mark 9 are moved from the state of FIG. 4 to the measurement position. The plate 15 is illuminated with exposure light emitted from the illumination optical system 1, and the amount of light transmitted through the substrate side mark 9 through the projection optical system 4 is detected by the detector 10. The substrate stage 6 is finely driven in the Z direction, and the coordinate position of Z ₀ at which the detected light quantity is maximum is calculated and acquired by the processing unit 12. The position where the detected light quantity becomes maximum is when the plate 15 and the substrate side mark 9 are in a conjugate positional relationship, and the focal position is calculated by searching for the position. The calculated focal position information is transmitted from the processing unit 12 to the main control unit 7, and a command is issued from the main control unit 7 to the substrate stage control unit 11, and the substrate stage 6 is driven in the Z direction by an amount corresponding to the deviation of the focal position. Thus, the focus position of the mask pattern can be adjusted to the substrate 5.

[Second Embodiment]
An exposure method will be described with reference to FIGS. FIG. 7 is a schematic view showing an exposure apparatus according to the second embodiment. 7, the same members as those in FIG. 4 are denoted by the same reference numerals, and the description thereof is omitted. FIG. 7A is a front view of the entire exposure apparatus, and FIG. 7B is a plan view showing details of the periphery of the mask stage. FIG. 7A is substantially the same as FIG. 4 of the first embodiment. However, the mask stage 3 that is driven only in the Y direction and one plate moving mechanism 16 that moves only in the X direction are configured. Is different from that mounted on the mask stage 3. Therefore, in the present embodiment, the plate moving mechanism 16 moves integrally with the mask stage 3, so that the plate 15 can move to any position on the plane (XY) perpendicular to the optical axis of the projection optical system 4. Become.

  FIG. 8 is a flowchart showing a method for performing focus calibration and exposing a substrate using the configuration of FIG. First, in S <b> 1, exposure conditions (exposure range, pattern, etc.) when transferring the actual device pattern of the mask 2 to the substrate 5 are input to the input unit 13. FIG. 9 shows an exposure range in the X direction (direction orthogonal to the scanning direction) in the present embodiment. The actual device pattern in the present embodiment is a pattern parallel to the Y direction (scanning direction). In S <b> 2, the main control unit 7 loads the mask 2 onto the mask stage 3. In S <b> 3, the main control unit 7 loads the substrate 5 onto the substrate stage 6. In S4, the main control unit 7 determines whether to correct the focal position. If the focal position is not corrected, the process proceeds to S12 and exposure is performed.

  In S5, the determination unit 14 determines the measurement position in the effective area of the projection optical system 4 and the first measurement pattern P of the plate 15 from the exposure condition input in S1. FIG. 10 shows measurement positions in the X direction in the present embodiment. In this embodiment, the points A and C at both ends of the exposure range in the X direction and the point B at the midpoint of the exposure range (X = 0) are measured. For the Y direction, the centers of the illumination ranges at points A, B, and C are measured. The plate 15 is the same as in FIG. 5 of the first embodiment. In the present embodiment, since the actual device pattern is a pattern parallel to the Y direction, the measurement pattern P1 of FIG. 5 that is also a pattern parallel to the Y direction is used for focus calibration. In the present embodiment, three measurement points and one type of first measurement pattern P are used, but the number of measurement points and the number of pattern types are not limited.

  In S6, the main control unit 7 determines that the center of the first measurement pattern P1 of the plate 15 is arranged at the measurement position (measurement points A, B, C) determined in S5, the driving mechanism of the mask stage 3, the plate It moves to a predetermined position using the moving mechanism 16. A command is issued from the main control unit 7 to the mask stage control unit 8 to drive the mask stage 3 to a predetermined position in the Y direction. Similarly, a command is issued from the main control unit 7 to the plate moving mechanism control unit 17, and the plate 15 is moved to a predetermined position in the X direction by the plate moving mechanism 16. In S7, the main control unit 7 issues a command to the substrate stage control unit 11 so that the substrate side mark 9 is arranged at a position corresponding to the plate 15, and drives the substrate stage 6 to a predetermined position. FIG. 11 shows the state of the exposure apparatus at the time of measurement in which the plate 15 and the substrate side mark 9 are moved to the measurement position from the state of FIG. FIG. 11A is a front view of the entire exposure apparatus, and FIG. 11B is a plan view showing details of the mask stage 3.

In S8, the main control unit 7 measures the shift of the focal position. The main control unit 7 finely drives the substrate stage 6 in the Z direction, and the processing unit 12 calculates the coordinate position of Z ₀ at which the detected light amount is maximum. In S9, the main control unit 7 determines whether measurement of all measurement points determined in S5 has been completed. If the measurement is not completed, the process returns to S6, and the focus position shift under the next measurement condition is measured. If the measurement has been completed, the process proceeds to S10. In S10, the processing unit 12 calculates the correction amount of the focal position based on the measurement result. Assuming that the shift amounts of the focus positions of the measurement points A, B, and C are F _A , F _B , and F _C , respectively, the focus position correction amount CF is expressed by Equation 1 below. However, when the focal position correction amount CF is a function of F _A , F _B , and F _C , it is not limited to Equation 1.
CF = {(F _A + F _C ) / 2 + F _B } / 2 (1)

  FIG. 12 shows the focal position shift amount and the focal position correction amount measured at the measurement points A, B, and C. FIG. In S <b> 11, the processing unit 12 transmits the focal position correction amount calculated in S <b> 10 to the main control unit 7, and the main control unit 7 issues a command to the substrate stage control unit 11 to move the substrate stage 6 to the focal position. Drives in the Z direction by the correction amount to correct the focal position. In the present embodiment, the focus position is corrected by driving the substrate stage 6, but the method for correcting the focus position is not limited. In S12, the main control unit 7 issues a command to the mask stage control unit 8 and the substrate stage control unit 11, and moves the mask stage 3 and the substrate stage 6 to the exposure position (X, Y). In S13, the illumination optical system 1 illuminates the mask 2 with exposure light, and the mask stage 3 and the substrate stage 6 are scanned in synchronism with the Y direction so that the pattern on the mask 2 changes the projection optical system 4. Then, only one shot is transferred to the substrate 5.

  In S14, the main control unit 7 determines whether exposure of all shots has been completed. If the exposure has not ended, the process returns to S12 to expose the next shot. If the exposure has been completed, the process proceeds to S15. In step S <b> 15, the main control unit 7 unloads the substrate 5 that has been exposed from the substrate stage 6. In S16, the main control unit 7 determines whether or not the pattern transfer to all the substrates 5 has been completed. If completed, the exposure is completed, and if not completed, S3 to S15 are repeated. According to this embodiment, exposure with focus calibration capable of measuring arbitrary measurement points and patterns within the effective area of the projection optical system 4 becomes possible.

[Device manufacturing method]
Next, a method for manufacturing a device (semiconductor device, liquid crystal display device, etc.) will be described. A semiconductor device is manufactured through a pre-process for producing an integrated circuit on a wafer and a post-process for completing an integrated circuit chip on the wafer produced in the pre-process as a product. The pre-process includes a step of exposing the wafer coated with the photosensitive agent using the above-described scanning exposure apparatus, and a step of developing the wafer. The post-process includes an assembly process (dicing and bonding) and a packaging process (encapsulation). A liquid crystal display device is manufactured through a process of forming a transparent electrode. The step of forming the transparent electrode includes a step of applying a photosensitive agent to a glass substrate on which a transparent conductive film is deposited, a step of exposing the glass substrate on which the photosensitive agent is applied using the above-described scanning exposure apparatus, and a glass Developing the substrate. According to the device manufacturing method of the present embodiment, it is possible to manufacture a higher quality device than before.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

2: Mask. 3: Mask stage. 4: Projection optical system. 5: Substrate. 6: Substrate stage. 9: Substrate side mark (second measurement pattern). 10: Detector. 15: Plate. 16: Plate moving mechanism. 20: Control unit. P, P1 to P4: Mask side marks (first measurement pattern).

Claims (11)

A mask stage that holds a mask; a substrate stage that holds a substrate; a projection optical system that projects the pattern of the mask onto the substrate; and a measurement unit that measures the imaging characteristics of the projection optical system. An exposure apparatus that exposes the substrate while driving the mask stage and the substrate stage in a scanning direction,
The measuring unit is
A plate having a first measurement pattern arranged at a position where the mask is to be arranged;
A second measurement pattern disposed on the substrate stage;
A plate moving mechanism that is provided separately from a driving mechanism that drives the mask stage and a driving mechanism that drives the substrate stage, and that moves the plate so that the first measurement pattern is disposed at a target image height position; ,
A detector for detecting light from the first measurement pattern, the projection optical system, and the second measurement pattern;
Including
The exposure apparatus characterized in that the measurement unit obtains the imaging characteristics from a detection result by the detector.   The exposure apparatus according to claim 1, wherein the plate moving mechanism is capable of moving the plate both in the scanning direction and in a direction orthogonal to the scanning direction.   The plate moving mechanism is mounted on the mask stage and can move the plate in a direction orthogonal to the scanning direction, and the plate can be moved in the scanning direction by driving the mask stage. The exposure apparatus according to claim 1.   A control unit configured to determine the target image height position according to an exposure area, and to control the plate moving mechanism so that the measurement unit measures the imaging characteristics at the determined image height position; The exposure apparatus according to any one of claims 1 to 3, wherein the exposure apparatus is characterized in that:   The exposure apparatus according to claim 4, wherein the control unit determines at least three target image height positions corresponding to both ends and a middle point of the exposure region.   The plate has a plurality of measurement patterns, and the control unit determines a measurement pattern to be used for measurement of the imaging characteristics from the plurality of measurement patterns according to the pattern of the mask. Item 6. The exposure apparatus according to Item 4 or 5.   The exposure apparatus according to claim 6, wherein the plurality of measurement patterns are line and space patterns different from each other in at least one of a line width, a pitch, and a line direction.   The exposure apparatus according to claim 1, wherein the measurement unit includes a plurality of sets each including the plate and the plate moving mechanism.   9. The exposure apparatus according to claim 1, wherein the imaging characteristic is a focus position or distortion of the projection optical system.   The said control part controls the drive of the said substrate stage so that the image formation characteristic of the said projection optical system may be corrected based on the measurement result of the said measurement part. The exposure apparatus described in 1. 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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