JP6929041B2 - Exposure equipment and manufacturing method of articles - Google Patents

Description

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

When manufacturing a semiconductor device or the like using a photolithography technique, a scanning exposure apparatus (scanner) that performs look-ahead type focus leveling control is used (see Patent Document 1). In such an exposure apparatus, it is required to shorten the settling time in order to improve the throughput. The settling time is a time (section) from when the scanning speed reaches the target speed to when the exposure is started in the scanning exposure in which the substrate is exposed while scanning the mask and the substrate. Immediately after the scanning speed reaches the target speed, the control deviation of the substrate stage is large. Therefore, if the exposure is started in such a state, the exposure accuracy of the end portion (shot end) of the shot region is lowered. Therefore, a settling time is provided as a time for converging the control deviation of the substrate stage. Similarly, the focus should be measured in a state where the stage control deviation has converged from the viewpoint of its accuracy.

In the look-ahead scanning type exposure apparatus, a sensor for measuring focus is arranged at a position distant from the exposure slit (projection position) in the scanning direction. Therefore, if the settling time is shortened, the focus is measured before the control deviation of the substrate stage converges. Therefore, as the settling time is shortened, the focus accuracy at the shot edge is lowered. Therefore, in the prior art, the exposure is completed, that is, the control deviation of the substrate stage is sufficiently converged without using the focus measurement value at the shot edge measured in the state where the control deviation of the substrate stage is large. The focus measurement value of the adjacent shot area measured in the state is used.

Japanese Patent No. 4953923

However, in the prior art, it is premised that the height (surface position) of the adjacent shot region and the height of the shot region to be exposed are substantially the same (similar). Therefore, if the height of the adjacent shot region and the height of the shot region to be exposed are different, the focus accuracy cannot be guaranteed and the focus accuracy is lowered.

An exemplary object of the present invention is to provide an exposure apparatus that is made in view of such problems of the prior art and is advantageous for improving focus accuracy.

In order to achieve the above object, the exposure apparatus as one aspect of the present invention is an exposure apparatus that transfers a mask pattern to a substrate, and is a stage that holds and moves the substrate and is held by the stage. Before the shot area of the substrate reaches the exposure area where the exposure to the shot area is performed, the positions of the plurality of measurement target points including the first measurement target point of the shot area in the height direction are measured. The position of the stage and the plurality of measured values measured by the first measuring unit that acquires a plurality of measured values and the position measuring unit that measures the position of the stage before the shot area reaches the exposed area. based on the position in the height direction of the shot area determined from a control unit that the height position of the shot area to control movement to the height direction of the stage so as to be positioned at the target position, The control unit has the control deviation of the stage in the height direction obtained from the position of the stage measured by the position measurement unit, and the shot region when the shot region reaches the exposure region. Based on the relationship between the position in the height direction of the shot region and the deviation from the target position, the control deviation value of the stage at which the deviation becomes a predetermined value is obtained as a threshold value, and the first measuring unit has the plurality of The plurality of measurements are based on the control deviation of the stage in the height direction and the threshold value obtained from the position of the stage measured by the position measuring unit when each of the measured values is acquired. It is characterized in that each of the values is weighted to obtain the position of the shot region in the height direction.

Further objects or other aspects of the invention will be manifested in the preferred embodiments described below with reference to the accompanying drawings.

According to the present invention, for example, it is possible to provide an exposure apparatus that is advantageous for improving focus accuracy.

It is the schematic which shows the structure of the exposure apparatus as one aspect of this invention. It is a figure which shows an example of the measurement point formed on the substrate by a focus measurement part. It is a figure which shows the relationship between the measurement point which the focus measurement part forms in the shot area of a substrate, and the exposure slit. It is a figure for demonstrating concretely the measurement of the height of the measurement target part of the shot area in an exposure process. It is a figure for demonstrating concretely the measurement of the height of the measurement target part of the shot area in an exposure process. It is a figure for demonstrating the principle that the focus accuracy decreases due to the control deviation of a substrate stage. It is a figure for demonstrating concretely the measurement of the height of the measurement target part of the shot area in the exposure process in this embodiment. It is a flowchart for demonstrating the exposure process in the exposure apparatus shown in FIG. It is a figure which shows an example of the arrangement of a plurality of shot regions of a substrate. It is a figure for demonstrating concretely the measurement of the height of the measurement target part of the shot area in the exposure process in this embodiment.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In addition, in each figure, the same member is given the same reference number, and duplicate description is omitted.

FIG. 1 is a schematic view showing a configuration of an exposure apparatus 100 as one aspect of the present invention. The exposure apparatus 100 transfers the pattern of the mask 12 to the substrate 15 by exposing the substrate 15 while scanning the mask 12 and the substrate 15. The exposure apparatus 100 is a step-and-scan scanning type exposure apparatus (scanner) in which the exposure region has a rectangular or arcuate slit shape, and the mask 12 and the substrate 15 are relatively scanned to expose a large angle of view. Is.

As shown in FIG. 1, the exposure apparatus 100 includes an illumination optical system 11, a mask stage 13, a projection optical system 14, a substrate stage 16, a focus measurement unit 17, a first position measurement unit 18, and a second. It has a position measuring unit 19 and a control unit 20. The control unit 20 controls the entire exposure apparatus 100, including a CPU and a memory. The control unit 20 controls each part of the exposure apparatus 100 to control a process of transferring the pattern of the mask 12 to the substrate 15, that is, a process of scanning and exposing the substrate 15.

The illumination optical system 11 includes a light-shielding member such as a masking blade, and shapes light from a light source (not shown) such as an excimer laser into, for example, a rectangular or arcuate slit shape having a longitudinal direction in the X direction. Illuminate (a part of) the mask 12 with. The mask stage 13 is a stage that holds and moves the mask 12. The substrate stage 16 is a stage that holds and moves the substrate 15. The mask 12 and the substrate 15 are arranged at optically conjugate positions via the projection optical system 14.

The projection optical system 14 has a predetermined projection magnification (for example, 1/2 times or 1/4 times), and projects the pattern of the mask 12 onto the substrate 15. The region on the substrate on which the pattern of the mask 12 is projected, that is, the region where the slit-shaped light is irradiated is hereinafter referred to as an exposure slit 21.

The mask stage 13 and the substrate stage 16 are configured to be movable in a direction (Y direction) perpendicular to the optical axis (Z direction) of the projection optical system 14, and have a speed corresponding to the projection magnification of the projection optical system 14 while synchronizing with each other. It is scanned relative to the ratio. As a result, the exposure slit 21 is scanned on the substrate, and the pattern of the mask 12 is transferred to the shot region 15a on the substrate. By sequentially performing such scanning exposure for each of the plurality of shot regions 15a on the substrate, the exposure process for one substrate 15 is completed.

The first position measuring unit 18 includes, for example, a laser interferometer and measures the position of the mask stage 13. The laser interferometer included in the first position measurement unit 18 irradiates the laser beam toward the reflector 13a provided on the mask stage 13, detects the laser beam reflected by the reflector 13a, and detects the laser beam on the mask stage 13. The displacement from the reference position of 13 is obtained. The first position measuring unit 18 acquires the current position of the mask stage 13 based on the displacement of the mask stage 13 from the reference position.

The second position measuring unit 19 includes, for example, a laser interferometer and measures the position of the substrate stage 16. The laser interferometer included in the second position measuring unit 19 irradiates, for example, a laser beam toward the reflector 16a provided on the substrate stage 16, detects the laser beam reflected by the reflector 16a, and detects the laser beam reflected by the reflector 16a on the substrate stage. Find the displacement of 16 from the reference position. The second position measuring unit 19 acquires the current position of the substrate stage 16 based on the displacement of the substrate stage 16 from the reference position. The control unit 20 moves the mask stage 13 and the substrate stage 16 in the XY directions based on the current positions of the mask stage 13 and the substrate stage 16 acquired by the first position measurement unit 18 and the second position measurement unit 19, respectively. Control the movement (drive). The first position measurement unit 18 and the second position measurement unit 19 include a laser interferometer in the present embodiment, but the present invention is not limited to this, and for example, an encoder may be included.

The focus measuring unit 17 has a function of measuring the surface position (position in the height direction) of the substrate 15, and measures and measures the position of the measurement target portion of the substrate 15 held on the substrate stage 16 in the height direction. Get the value. The focus measuring unit 17 measures the position of the measurement target portion of the substrate 15 in the height direction while the substrate stage 16 is moving in order to match the image plane of the projection optical system 14 with the surface of the substrate 15. .. The focus measurement unit 17 is an obliquely incident type that irradiates the substrate 15 with light from an angle, and includes an irradiation system 17a that irradiates the substrate 15 with light and a light receiving system 17b that receives the light reflected by the substrate 15. including. The focus measurement unit 17 includes a first measurement unit and a second measurement unit having these configurations, respectively. In the present embodiment, the first measurement unit determines each of the plurality of measurement target points including the first measurement target point of the shot area before the shot region of the substrate 15 held on the substrate stage 16 reaches the exposure slit. The position in the height direction of is measured and a plurality of measured values are acquired. When the shot region of the substrate 15 held on the substrate stage 16 reaches the exposure slit, the second measuring unit measures the position of the shot region in the height direction of the first measurement target portion and acquires the measured value. do. In this way, the first measuring unit measures the height of the shot region to be exposed in the Z direction prior to the second measuring unit.

The irradiation system 17a includes, for example, a light source 70, a collimator lens 71, a slit member 72, an optical system 73, and a mirror 74. The light source 70 emits light having a wavelength that does not expose the resist (photosensitive agent) supplied on the substrate, including, for example, a lamp or a light emitting diode. The collimator lens 71 converts the light emitted from the light source 70 into parallel light having a substantially uniform light intensity distribution in the cross section. The slit member 72 is composed of a pair of prisms bonded so that their slopes face each other, and the bonded surfaces are provided with a light-shielding film such as chromium having a plurality of openings, for example, nine pinholes. It is provided.

The optical system 73 is a telecentric optical system on both sides, and allows light that has passed through each of the nine pinholes formed in the slit member 72 to enter the substrate 15 via the mirror 74. The optical system 73 is configured such that the bonding surface of the slit member 72 on which the pinhole is formed and the surface of the substrate 15 satisfy the conditions of Scheimpflug. The mirror 74 is configured such that the incident angle (angle between the optical axis of the projection optical system 14 and the light) φ of each light from the optical system 73 on the substrate is, for example, 70 degrees or more. .. Further, as shown in FIG. 2, the irradiation system 17a forms an angle θ (for example, 22.5 degrees) with respect to the scanning direction (Y direction) in the direction parallel to the surface of the substrate 15 (XY direction). It is configured so that each light is incident on the substrate 15. As shown in FIG. 2, by injecting nine lights from the irradiation system 17a onto the substrate 15, the position in the height direction of the measurement target portion of the shot region of the substrate 15 is measured at each of the nine measurement points 30. Is possible.

The light receiving system 17b includes, for example, a mirror 75, a light receiving optical system 76, a correction optical system 77, and a photoelectric conversion unit 78. The mirror 75 guides the nine lights reflected by the substrate 15 to the light receiving optical system 76. The light receiving optical system 76 is a bilateral telecentric optical system and includes a diaphragm commonly provided for nine lights. The aperture included in the light receiving optical system 76 blocks high-order diffracted light (noise light) caused by the pattern formed on the substrate 15. The correction optical system 77 includes nine lenses corresponding to each of the nine lights, and images each of the nine lights on the photoelectric conversion unit 78 (light receiving surface) to form a pinhole image. The photoelectric conversion unit 78 includes nine photoelectric conversion elements corresponding to each of the nine lights. As the photoelectric conversion element, for example, a CCD line sensor, a CMOS line sensor, or the like is used. The processing unit 79 determines the position in the height direction of each measurement target portion in the shot region of the substrate 15 based on the position of the image of each pinhole formed in the photoelectric conversion unit 78.

By configuring the irradiation system 17a and the light receiving system 17b in this way, the focus measuring unit 17 increases the height of each measurement target portion in the shot region of the substrate 15 based on the position of the image of each pinhole in the photoelectric conversion unit 78. The position in the vertical direction can be measured. The control unit 20 bases the substrate 15 so that the height position of the substrate 15 is located at the target position based on the measured values acquired by the focus measurement unit 17 by the time the shot region of the substrate 15 reaches the exposure slit. The movement of the stage 16 in the height direction (Z direction) is controlled. In the light receiving system 17b, tilt correction is performed so that each measurement point 30 and the photoelectric conversion unit 78 (light receiving surface) are conjugate to each other. Therefore, the position of the image of each pinhole in the photoelectric conversion unit 78 does not change depending on the local inclination at each measurement point 30.

FIG. 3 is a diagram showing the relationship between _{the nine measurement points 30a 1 to} 30a ₃ , 30b _{1 to} 30b _3, and 30c _{1 to} 30c ₃ formed by the focus measurement unit 17 in the shot region 15a, and the exposure slit 21. The exposure slit 21 is a rectangular exposure area shown by a broken line in FIG. The measurement points 30a ₁ , 30a ₂ and 30a ₃ are measurement points formed in the exposure slit 21 and measure the position in the height direction of the measurement target portion in parallel with the exposure of the shot region 15a (focus measurement). It is a measurement point for. The measurement points 30b ₁ , 30b ₂ and 30b ₃ and the measurement points 30c ₁ , 30c ₂ and 30c ₃ are separated from the exposure slit 21 (measurement points 30a ₁ , 30a ₂ and 30a ₃ ) by a distance Lp along the scanning direction. It is a measurement point formed at a vertical position.

In the present embodiment, the measurement points 30b ₁ , 30b ₂ and 30b ₃ and the measurement points 30c ₁ , 30c ₂ and 30c ₃ are the measurement points of the first measurement unit of the focus measurement unit 17. The measurement points 30a ₁ , 30a ₂ and 30a ₃ are measurement points of the second measurement unit of the focus measurement unit 17. The measurement point of the first measurement unit and the measurement point of the second measurement unit are switched and used according to the scanning direction.

The control unit 20 can control the measurement timing of each measurement point 30 by the focus measurement unit 17 based on the distance between the exposure slit 21 and each measurement point 30, and the scanning direction and scanning speed of the substrate stage 16. .. The measurement points 30a ₁ , 30b ₁ and 30c ₁ are formed at the same X coordinate position. Further, the measurement points 30a ₂ , 30b ₂ and 30c ₂ are formed at the same X coordinate position. Further, the measurement points 30a ₃ , 30b ₃ and 30c ₃ are formed at the same X coordinate position. Therefore, for example, when scanning the substrate stage 16 in the Y direction, the same coordinate position of the shot region 15a can be measured at different measurement points by adjusting the measurement timing of each measurement point 30.

For example, consider a case where the substrate 15 is exposed while scanning the substrate stage 16 in the direction indicated by the arrow F. In this case, the control unit 20 _{determines the position of the measurement target point in the height direction at the measurement points 30b 1 to} 30b ₃ prior to the measurement of the position in the height direction of the measurement target point at the _{measurement points 30a 1 to} 30a _3. The measurement timing is controlled so that the measurement of is performed. The control unit 20 calculates the position in the height direction (position in the Z direction) of the exposure target area including the measurement target portion of the shot region 15a based on the measurement values (measurement results) at the _{measurement points 30b 1 to} 30b _3. do. The control unit 20 moves the substrate stage 16 in the Z direction (height direction of the substrate 15) so that the exposure target region is located at the target position by the time the exposure target region reaches the exposure slit 21. Here, the target position is the position (best focus position) of the image plane of the pattern of the mask 12, that is, the image plane of the projection optical system 14. However, the target position does not mean a position that completely matches the position of the image plane of the projection optical system 14, but includes a position within the allowable depth of focus.

Further, consider a case where the substrate 15 is exposed while scanning the substrate stage 16 in the direction indicated by the arrow R. In this case, the control unit 20 _{determines the position of the measurement target point in the height direction at the measurement points 30c 1 to} 30c ₃ prior to the measurement of the position in the height direction of the measurement target point at the _{measurement points 30a 1 to} 30a _3. The measurement timing is controlled so that the measurement of is performed. The control unit 20 calculates the position in the height direction of the exposure target area including the measurement target portion of the shot area 15a based on the measurement values at the _{measurement points 30c 1 to} 30c _3. The control unit 20 moves the substrate stage 16 in the Z direction so that the exposure target region is located at the target position by the time the exposure target region reaches the exposure slit 21.

With reference to FIGS. 4 (a) and 4 (b), the measurement of the position in the height direction of the measurement target portion of the shot region in the process of scanning and exposing the substrate 15 will be specifically described. FIG. 4A is a diagram showing an exposure slit 21, a measurement point 30, a shot region 15a, a measurement target portion 40, and a movement locus 21a of the substrate stage 16. The shot area 15a ₁ is a shot area where the exposure process has been performed. The shot area 15a ₂ is a shot area where the exposure process is performed next to _{the shot area 15a 1 , and the shot area 15a 3} is a shot area where the exposure process is performed next to the _{shot area 15a 2.} There are a plurality of measurement target points of the shot area 15a with respect to the Y direction in order to measure the position of the shot area 15a in the height direction as a whole. However, in FIG. 4A, for simplification, only the measurement target locations 40a ₁ , 40a ₂ , 40a ₃ , 40b ₁ , 40b ₂ , and 40b ₃ are shown. Here, a case where the exposure process is performed on the shot region 15a _{2 will be described.} Further, FIG. 4B is a diagram showing the relationship between the moving speed of the substrate stage 16 in the Y direction and the time when the substrate stage 16 moves on the moving locus 21a. In FIG. 4B, the vertical axis represents the moving speed of the substrate stage 16 in the Y direction, and the horizontal axis represents time (time).

As shown in FIG. 4A, when _{the exposure process of the shot area 15a 1} is completed, the substrate stage 16 moves in the X direction while decelerating in the Y direction, and then moves to the shot area 15a _{2 in} which the exposure process is performed. do. When the substrate stage 16 reaches the acceleration start point in the Y direction, the substrate stage 16 is accelerated and moved in the direction indicated by the arrow F. In FIG. 4B, the time from time t1 to time t2 corresponds to the time during which the substrate stage 16 is decelerated, and the time from time t2 to time t3 corresponds to the time during which the substrate stage 16 is accelerated. .. Further, in the time from time t1 to time t5, the substrate stage 16 is moved in the −X direction so that the measurement and scanning exposure at the measurement points 30a _{1 to} 30a _{3 with respect to the shot region 15a 2 can be started.} At this time, it is sufficient that the moving speed of the substrate stage 16 in the Y direction reaches the target speed by the time the shot region 15a _{2 reaches the exposure slit 21.}

From the viewpoint of focus accuracy, the moving speed of the substrate stage 16 has reached the target speed by the time t4 when the measurement at the _{measurement points 30b 1 to} 30b _{3 is started, and the control deviation of the substrate stage 16 has sufficiently converged.} It is good. The time from time t3 to time t4 corresponds to the convergence waiting time of the control deviation of the substrate stage 16. Here, the time from the time t3 to _{the time t5 at which the exposure of the shot region 15a 2} is started is referred to as a settling time.

After the settling time has elapsed, the shot region 15a ₂ is exposed while moving the substrate stage 16 at a constant speed. In FIG. 4B, the time from the time t5 to the time t6 corresponds to the time during which the shot region 15a ₂ is exposed. At this time, the positions of the measurement target points 40 in the shot region 15a2 in the height direction are measured at the measurement points 30b1 to 30b3. Then, based on the measured values at the measurement points 30b _{1 to} 30b ₃ , the substrate is set so that the exposure target area is located at the target position by the time the exposure target area including the measurement target portion 40 reaches the exposure slit 21. The stage 16 is moved in the Z direction (the height direction of the substrate 15).

Specifically, when the measurement target portions 40a ₁ through 40a ₃ shot region 15a ₂ reaches the measurement point 30b ₁ to 30b _3, the height direction of the measurement target portions 40a ₁ to 40a ₃ in the measurement point 30b ₁ to 30b ₃ Measure the position of each. Further, based on the measured values at the measurement points 30b _{1 to} 30b ₃ , the position in the height direction of the exposure target area including _{the measurement target points 40a 1 to} 40a _{3 is determined.} Then, the substrate stage 16 is moved in the Z direction so that the exposure target region is located at the target position by the time the exposure target region including the measurement target locations 40a _{1 to} 40a _{3 reaches the exposure slit 21.}

Then, when the measurement target portions 40b ₁ to 40b ₃ of the shot regions 15a ₂ reaches the measurement point 30b ₁ to 30b _3, the position in the height direction of the measurement target portions 40b ₁ to 40b ₃ in the measurement point 30b ₁ to 30b ₃ Measure each. Further, based on the measured values at the measurement points 30b _{1 to} 30b ₃ , the position in the height direction of the exposure target area including _{the measurement target points 40b 1 to} 40b _{3 is determined.} Then, the substrate stage 16 is moved in the Z direction so that the exposure target region is located at the target position by the time the exposure target region including the measurement target locations 40b _{1 to} 40b _{3 reaches the exposure slit 21.}

Here, a case where the settling time is shortened and the throughput is improved will be described with reference to FIGS. 5 (a) and 5 (b). FIG. 5A is a diagram showing an exposure slit 21, a measurement point 30, a shot region 15a, a measurement target portion 40, and a movement locus 21b of the substrate stage 16. As described above, the shot area 15a ₁ is a shot area where the exposure process has been performed. Similarly, the shot area 15a ₂ is a shot area where the exposure process is performed next to _{the shot area 15a 1 , and the shot area 15a 3} is a shot area where the exposure process is performed next to the _{shot area 15a 2.} Here, a case where the exposure process is performed on the shot region 15a _{2 will be described.} Further, FIG. 5B is a diagram showing the relationship between the moving speed of the substrate stage 16 in the Y direction and the time when the substrate stage 16 moves along the moving locus 21b. In FIG. 5B, the vertical axis represents the moving speed of the substrate stage 16 in the Y direction, and the horizontal axis represents time (time).

As shown in FIG. 5A, when _{the exposure process of the shot area 15a 1} is completed, the substrate stage 16 moves in the X direction while decelerating in the Y direction, and then moves to the shot area 15a _{2 in} which the exposure process is performed. do. The movement locus 21b shortens the time from when the movement speed of the substrate stage 16 reaches the target speed to when the measurement at the measurement points 30b _{1 to} 30b ₃ is started, that is, the time from the time t3 to the time t4. It is decided to. Therefore, the movement locus 21b is shorter than the movement locus 21a, and the throughput is improved by that amount. On the other hand, the control deviation of the substrate stage 16 is sufficiently converged by shortening the time from when the moving speed of the substrate stage 16 reaches the target speed to when the measurement at the measurement points 30b _{1 to} 30b _{3 is started.} Focus measurement will be performed in the state where it is not. If the focus measurement is performed in a state where the control deviation of the substrate stage 16 is not sufficiently converged, the focus accuracy will be lowered.

With reference to FIG. 6, the principle that the focus accuracy is lowered due to the control deviation of the substrate stage 16 will be described. In FIG. 6, the vertical axis represents the control deviation of the substrate stage 16 in the Z direction, and the horizontal axis represents time. In FIG. 6, in a state where the control deviation 50 of the substrate stage 16 in the Z direction has not converged, the positions of the measurement target points 40a _{1 to} 40a _{3 in} the height direction are measured _{at the measurement points 30b 1 to} 30b _{3, respectively.} It shall be. Further, the control deviation 50 of the substrate stage 16 in the Z direction is measured at a predetermined sampling interval T _s by using the second position measuring unit 19 in the present embodiment, and is shown as measured values 50a to 50i in FIG. ing. Instead of the second position measuring unit 19, a dedicated laser interferometer for measuring the position of the substrate stage 16 in the Z direction may be provided to measure the control deviation 50 of the substrate stage 16 in the Z direction.

The measured values at the measurement points 30b _{1 to} 30b ₃ are the average positions in the height direction of the measurement target points 40a _{1 to} 40a _{3 in the measurement period TF.} However, in the state where the control deviation 50 of the substrate stage 16 has not converged _{, the measured values at the measurement points 30b 1 to} 30b ₃ include the amount of position change in the height direction due to the control deviation 50 of the substrate stage 16. Become. Therefore, the position in the height direction of the exposure target area including the measurement target points 40a _{1 to} 40a ₃ is the amount of change in the height direction due to the control deviation 50 of the substrate stage 16 from the measured values at the measurement _{points 30b 1 to} 30b _3. It is necessary to remove (correct) and obtain.

It is conceivable that the amount of change in the position of the substrate stage 16 in the height direction due to the control deviation 50 is, for example, the average value 60a of the discrete measurement values 50d to 50h of the second position measurement unit 19 in the _{measurement period TF.} However, in reality, _{the average value 60b of the control deviation 50 of the continuous substrate stage 16 in the measurement period TF} is the amount of position change in the height direction due to the correct control deviation 50 of the substrate stage 16. Therefore, the difference between the average value 60a and the average value 60b is the error F _Err . Such an error F _Err causes a shift in the position of the exposure target region in the height direction, which is a factor of lowering the focus accuracy.

In the prior art, the measurement target location of the _{shot region (adjacent shot region) 15a 1} where the exposure is completed is not used without using the measurement value of _{the measurement target location 40a 1 to} 40a _{3 of the shot region 15a 2.} The measured values of the positions of 39a _{1 to} 39a _{3 in the height direction are used. Specifically, the shot area 15a 2} is measured based on the position in the height direction of the measurement target points 39a _{1 to} 39a _{3 of the shot area 15a 1} measured in a state where the control deviation of the substrate stage 16 is sufficiently converged. The positions of the target locations 40a _{1 to} 40a _{3 in} the height direction are estimated. However, in the prior art, the focus accuracy is improved on the premise that _{the height (surface position) of the shot region 15a 1 and} the height of the shot region 15a _{2 are substantially the same.} Therefore, if _{the height of the shot area 15a 1 and} the height of the shot area 15a ₂ are different, the focus accuracy cannot be improved.

Therefore, in the present embodiment, based on the information regarding the control deviation of the substrate stage 16 when the focus measuring unit 17 (first measuring unit) measures the position of the substrate 15 in the height direction and acquires the measured value. , The measured value is weighted to obtain the position of the shot area in the height direction. As a result, it is possible to reduce a decrease in focus accuracy due to a control deviation of the substrate stage 16.

With reference to FIGS. 7 (a) to 7 (c), the measurement of the position in the height direction of the measurement target portion of the shot region in the process of scanning and exposing the substrate 15 in the present embodiment will be specifically described. FIG. 7A is a diagram showing an exposure slit 21, a measurement point 30, a shot region 15a, a measurement target portion 40, and a movement locus 21b of the substrate stage 16. As described above, the measurement target location 40 includes the measurement target locations (first measurement target locations) 40a _{1 to} 40a ₃ (40b _{1 to} 40b ₃ ) _{in the shot area 15a 2.} Further, in the present embodiment, the measurement target points 40 are the measurement target points (second measurement target points) 40d _{1 to} 40d ₃ , 40e _{1 to} 40e ₃ , and the _{area outside the shot area 15a 2 (outside the shot area).} , 40f _{1 to} 40f ₃ are further included. In this embodiment, three measurement target points (40d _{1 to} 40d ₃ , 40e _{1 to} 40e ₃ , and 40f _{1 to} 40f ₃ ) are newly added to the area outside the shot area. It is not limited to. For example, at least one measurement target location (any of 40d _{1 to} 40d ₃ , 40e _{1 to} 40e ₃ , and 40f _{1 to} 40f ₃ ) may be newly added. Also, the shot and the region outside the region, a region where the exposure slit reaches before the shot area reaches the exposure slit, in the present embodiment, the shot region 15a ₁ and a shot area in the movement trajectory 21b of the substrate stage 16 This is the area between 15a and _2. FIG. 7B is a diagram showing the relationship between the moving speed of the substrate stage 16 in the Y direction and the time when the substrate stage 16 moves on the moving locus 21b. In FIG. 7B, the vertical axis represents the moving speed of the substrate stage 16 in the Y direction, and the horizontal axis represents time (time). Further, FIG. 7 (c), the control deviation of the substrate stage 16 in the Z direction, the shot region 15a ₂ of the deviation of the height direction of the position and the target position of the shot area 15a ₂ upon reaching the exposure region It is a figure which shows an example of a relationship. In FIG. 7C, the vertical axis _{indicates the deviation of the position of the shot region 15a 2 in} the height direction from the target position, and the horizontal axis indicates the height direction of the measurement target points at the measurement _{points 30b 1 to} 30b _3. The control deviation of the substrate stage 16 in the Z direction at the time of measuring the position of is shown.

A method of acquiring the relationship shown in FIG. 7 (c) will be described with reference to FIG. 7 (a). The relationship shown in FIG. 7C is acquired in advance before the substrate 15 is exposed. First, while moving the substrate stage 16 along the movement locus 21b, the _{positions of the measurement target points 40a 1 to} 40a ₃ at the end (shot end) of the shot region 15a are _{measured at the measurement points 30b 1 to} 30b _3. And acquire the measured value (first measured value). At this time, the second position measuring unit 19 measures the control deviation of the substrate stage 16 when the _{measurement points 30b 1 to} 30b ₃ are measuring the positions of the measurement target points 40a _{1 to} 40a _{3 in the height direction.} get. Further, based on the measured values at the measurement points 30b _{1 to} 30b ₃ , the position in the height direction of the region including _{the measurement target points 40a 1 to} 40a _{3 is determined.} Then, the substrate stage 16 is moved in the Z direction so that the region including the measurement target points 40a _{1 to} 40a ₃ reaches the exposure slit 21 so that the region is located at the target position.

Then, in the measurement point 30a ₁ to 30a _3, acquires and measures the position in the height direction of the measurement target portions 40a ₁ to 40a ₃ of shot areas 15a and measured value (second measure). Then, the difference between _{the measured values (second measured values) at the measured points 30a 1 to} 30a ₃ and the measured values (first measured values) at the above-mentioned measurement points 30b _{1 to} 30b ₃ is calculated in the shot area 15a _2. It is acquired as the deviation of the position in the height direction from the target position. However, if it is adjusted to the best focus position of projection optical system 14 and the zero point of the measurement points 30a1 to 30a3 are the same, the measured value at the measurement point 30a ₁ to 30a _3, the shot region 15a ₂ It may be a deviation from the target position of the position in the height direction of.

By plotting the control deviation of the substrate stage 16 acquired in this way and the deviation from the target position as shown in FIG. 7C, the relationship between the control deviation of the substrate stage 16 and the deviation from the target position is obtained. Can be obtained. Further, by performing the above-described processing on each shot region of the substrate 15, the relationship between the control deviation of the substrate stage 16 and the deviation from the target position corresponding to each shot region can be acquired.

Then, based on the relationship shown in FIG. 7 (c) and the focus allowable value, a threshold value for compensating the measured values acquired at the _{measurement points 30b 1 to} 30b _{3 with respect to the control deviation of the substrate stage 16 is obtained.} .. Such a threshold value is used as information regarding the control deviation of the substrate stage 16 as described later. In the present embodiment, the relationship between the magnitude of the control deviation of the substrate stage 16 and the deviation from the target position is acquired, but the present invention is not limited to this, and the amount of change in the control deviation of the substrate stage 16 and the target position are obtained. The relationship with the deviation from may be acquired.

The process of scanning and exposing the substrate 15 in this embodiment will be described. First, while moving the substrate stage 16 along the movement locus 21b, at the measurement points 30b _{1 to} 30b ₃ , the newly added measurement target points 40d _{1 to} 40d ₃ , 40e _{1 to} 40e ₃ , and 40f _{1 to} 40f ₃ The measured value is acquired by measuring the position in the height direction. Subsequently, at the measurement points 30b _{1 to} 30b ₃ , the positions of the measurement target points 40a _{1 to} 40a ₃ in the shot area 15a in the height direction are measured and the measured values are acquired. At this time, the second position measuring unit 19 measures the positions of the measurement target points 40d _{1 to} 40d ₃ , 40e _{1 to} 40e ₃ , and 40f _{1 to} 40f _{3 in} the height direction at the _{measurement points 30b 1 to} 30b _3. The control deviation of the substrate stage 16 at the time of operation is measured and acquired. As shown in FIG. 7B, the positions of the measurement target points 40d _{1 to} 40d ₃ , 40e _{1 to} 40e ₃ , and 40f _{1 to} 40f ₃ are measured in the height direction during the acceleration of the substrate stage 16. It may be provided at the position where it is used.

In this way, at the measurement points 30b _{1 to} 30b ₃ , the positions in the height direction of the measurement target points 40d _{1 to} 40d ₃ , 40e _{1 to} 40e ₃ , 40f _{1 to} 40f ₃ , and 40a _{1 to} 40a _{3 are measured in order.} Get multiple measurements. Then, among the plurality of measured values, the exposure target area including _{the measurement target points 40a 1 to} 40a ₃ is based on the measured values in which the control deviation of the substrate stage 16 when the measured values are acquired does not exceed the threshold value. Determine the position in the height direction of. In other words, among a plurality of measured values, the exposure including _{the measurement target points 40a 1 to} 40a ₃ without using the measured value in which the control deviation of the substrate stage 16 when the measured value is acquired exceeds the threshold value. Determine the position of the target area in the height direction. This is an exposure including _{the measurement target points 40a 1 to} 40a ₃ with the weight given to the measurement value in which the control deviation of the substrate stage 16 when the measurement value is acquired exceeds the threshold value being zero among a plurality of measurement values. It corresponds to determining the position of the target area in the height direction.

As described above, in the present embodiment, the measurement values at the measurement target points 40d _{1 to} 40d ₃ , 40e _{1 to} 40e ₃ , and 40f _{1 to} 40f _{3 close to the shot area 15a 2} are selectively used to measure the measurement target points 40a. The position in the height direction of the exposure target area including _{1 to} 40a _{3 is determined.} Therefore, in the present embodiment, _{the position of the shot area 15a 2 in} the height direction is more accurate than the case where the measured values of the measurement target points 39a _{1 to} 39a ₃ of the shot area 15a _{1 adjacent to the shot area 15a 2 are used.} Can be asked for. Therefore, even when _{the height of the shot area 15a 1 and} the height of the shot area 15a ₂ are different, the focus accuracy can be improved.

Further, in the present embodiment, the measurement target points are newly added to the area outside the shot area, but the measurement target points 40a _{1 to} 40a ₃ , 40b _{1 to} 40b ₃ , ... The above-mentioned processing may be performed on. For example, when the control deviation of the substrate stage 16 when measuring the positions of the measurement target points 40a _{1 to} 40a _{3 in} the height direction exceeds the threshold value, the measurement values of the _{measurement target points 40b 1 to} 40b _{3 are measured.} Based on, the position of the shot area in the height direction is determined.

Further, the weight given to the measured value of each measurement target portion may be changed depending on whether or not the control deviation of the substrate stage 16 exceeds the threshold value. For example, it is assumed that the control deviation of the substrate stage 16 when measuring the positions of the measurement target points 40d _{1 to} 40d ₃ and 40e _{1 to} 40e _{3 in the height direction exceeds the threshold value.} Further, it is assumed that the control deviation of the substrate stage 16 when measuring the positions of the measurement target points 40f _{1 to} 40f ₃ and 40a _{1 to} 40a _{3 in the height direction does not exceed the threshold value.} In this case, the _{weights given to the measured values of the measurement target points 40d 1 to} 40d ₃ and 40e _{1 to} 40e ₃ and the weights given to the measurement values of the measurement target points 40f _{1 to} 40f ₃ and 40a _{1 to} 40a ₃ Are set separately. Here, the weight given to the measurement values of the _{measurement target points 40d 1 to} 40d ₃ and _{the measurement values of 40e 1 to} 40e ₃ in which the control deviation of the substrate stage 16 exceeds the threshold value is defined as the first weight. Further, the weight given to the measurement values of the _{measurement target points 40f 1 to} 40f ₃ and _{the measurement values 40a 1 to} 40a ₃ in which the control deviation of the substrate stage 16 does not exceed the threshold value is defined as the second weight. Then, the first weight is made smaller than the second weight. As a result, the position of the shot region in the height direction can be determined while reducing the influence of the measured value in which the control deviation of the substrate stage 16 exceeds the threshold value.

Further, it is also conceivable that the control deviation of the substrate stage 16 exceeds the threshold value at all of the measurement target points 40d _{1 to} 40d ₃ , 40e _{1 to} 40e ₃ , 40f _{1 to} 40f ₃ , and 40a _{1 to} 40a _3. .. In such a case, the _{substrate stage 16 may be moved in the Y direction without exposing the shot region 15a 2} , the settling time may be changed, and then the shot region 15a ₂ may be exposed (retry exposure). Further, when the substrate stage 16 is moved in the Y direction without exposing the shot region 15a ₂ , the position in the height direction of each measurement target portion is measured at the measurement points 30a _{1 to} 30a ₃ , and the measured value is obtained. Based on this, the position in the height direction of the shot region at the time of retry exposure may be obtained. When a lot of retry exposures occur, the control parameters (movement speed, acceleration, movement locus, etc.) of the substrate stage 16 are changed so that the relationship shown in FIG. 7C is acquired.

The operation in the exposure apparatus 100, that is, the exposure process will be described with reference to FIG. As described above, the exposure process is performed by the control unit 20 controlling each unit of the exposure apparatus 100 in an integrated manner.

In S802, the substrate 15 is carried into the exposure apparatus 100. Specifically, the substrate 15 is conveyed by a conveying hand (not shown), and the substrate 15 is held by the substrate stage 16.

In S804, pre-alignment (pre-measurement and correction) for global alignment is performed. Specifically, the rotation error of the substrate 15 using the low magnification field alignment microscope (not shown) so that the alignment mark on the substrate 15 fits within the measurement range of the high magnification field alignment microscope (not shown) used for global alignment. The amount of deviation such as is measured and corrected.

Global tilt is performed in S806. Specifically, as shown in FIG. 9, the focus measuring unit 17 measures the position of the sample shot region 200 in the height direction among the plurality of shot regions of the substrate 15. Then, the overall inclination of the substrate 15 is calculated and corrected based on the position in the height direction of the sample shot region 200 measured by the focus measuring unit 17.

In S808, pre-adjustment is performed for measuring the position of the substrate 15 in the height direction during exposure (during scanning of the mask stage 13 and the substrate stage 16). The pre-adjustment includes, for example, adjustment of the amount of light of the light source 70 of the focus measurement unit 17, memory of the pattern step in the shot region of the substrate 15, and the like.

In S810, the projection optical system 14 is adjusted. Specifically, using the light amount sensor and the reference mark (not shown) arranged on the substrate stage 16 and the reference plate (not shown) arranged on the mask stage 13, the inclination and curvature of field of the projection optical system 14 are used. Ask for. For example, the change in the amount of exposure light when the substrate stage 16 is scanned in the X, Y, and Z directions is measured by a light amount sensor arranged on the substrate stage 16. Then, the projection optical system 14 is adjusted by obtaining the amount of deviation of the reference mark with respect to the reference plate based on the change in the amount of exposure light.

Global alignment is performed in S812. Specifically, the alignment mark of the substrate 15 is measured using a high-magnification field alignment microscope, and the total deviation amount of the substrate 15 and the common deviation amount in each shot region are obtained. In order to measure the alignment mark with high accuracy, the alignment mark must be located at the position where the contrast of the alignment mark is the best contrast (best contrast position). A focus measuring unit 17 and an alignment microscope may be used to measure the best contrast position. For example, the substrate stage 16 is moved to a predetermined height (position in the Z direction), the contrast is measured with an alignment microscope, and the focus measurement unit 17 repeatedly measures the position of the substrate 15 in the Z direction. At this time, the measurement result of the contrast corresponding to each position of the substrate stage 16 in the Z direction and the measurement result of the position of the substrate 15 in the Z direction are stored in association with each other. Then, based on the measurement results of the plurality of contrasts, the position of the substrate stage 16 having the highest contrast in the Z direction is obtained and set as the best contrast position.

In S814, the substrate 15 is exposed (scanning exposure). Specifically, the focus measuring unit 17 measures the position of each measurement target portion of the substrate 15 in the height direction, and based on the measured value, the substrate stage 16 targets the position of the shot region of the substrate 15 in the Z direction. The shot area is exposed while being positioned. At this time, as described above, the measured value of each measurement target location is weighted based on whether the control deviation of the substrate stage 16 when measuring the position in the height direction of each measurement target location exceeds the threshold value. Given, the position of the shot area in the height direction is obtained. Further, when the substrate 15 is the first substrate of the lot, it is necessary to acquire the relationship shown in FIG. 7C to obtain the threshold value before exposing the substrate 15.

In S816, the substrate 15 is carried out from the exposure apparatus 100. Specifically, the exposed substrate 15 is received from the substrate stage 16 by a transport hand (not shown) and transported to the outside of the exposure apparatus 100.

The method for manufacturing an article according to the embodiment of the present invention is suitable for producing an article such as a device (semiconductor element, magnetic storage medium, liquid crystal display element, etc.). Such a manufacturing method includes a step of exposing a substrate coated with a photosensitizer and a step of developing the exposed substrate using an exposure apparatus 100. In addition, such a manufacturing method may include other well-known steps (oxidation, film formation, vapor deposition, doping, flattening, etching, resist peeling, dicing, bonding, packaging, etc.). The method for producing an article in 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.

So far, the exposure apparatus 100 has been described as a step-and-scan scanning type exposure apparatus. However, the exposure apparatus 100 may be a step-and-repeat exposure apparatus (stepper).

With reference to FIGS. 10A to 10C, measurement of the position in the height direction of the measurement target portion of the shot region when the exposure apparatus 100 is a stepper will be described. 10 (a) to 10 (c) are diagrams showing a measurement point 30 and a measurement target location 40 when _{the shot region 15a 2 of the substrate 15 is exposed.} 10 (a) to 10 (c) show a shot region 15a _{1 in} which the exposure process is performed, and a shot region 15a _{2 in} which the exposure process is performed next to the shot area 15a _1. Here, a case where the exposure process is performed on the shot region 15a _{2 will be described.} In order to make it easier to see the newly added measurement target points 40h and 40i with respect to the conventional measurement target points 40j, FIGS. 10 (a), 10 (b) and 10 (c) are shown separately. .. FIG. 10 (c) shows the conventional measurement target points 40j, and FIGS. 10 (a) and 10 (b) show the newly added measurement target points 40h and 40i, respectively.

A method of acquiring the relationship shown in FIG. 7C will be described when the exposure apparatus 100 is a stepper. First, while moving the substrate stage 16 stepwise in the direction of the arrow F, the position in the height direction of the measurement target portion 40h is measured at the measurement point 30, and the measurement value (first measurement value) is acquired. At this time, the second position measurement unit 19 measures and acquires the control deviation of the substrate stage 16 when the position in the height direction of the measurement target portion 40h is measured at the measurement point 30. Further, based on the measured value at the measurement point 30, the position in the height direction of the region including the measurement target portion 40h is determined. Then, the substrate stage 16 is moved in the Z direction so that the region including the measurement target portion 40h is located at the target position.

Next, at the measurement point 30, the position in the height direction of the measurement target point 40j is measured and the measured value (second measured value) is acquired. Then, the difference between the second measured value and the above-mentioned first measured value is acquired as a deviation from the target position of the position in the height direction of _{the shot region 15a 2.}

By plotting the control deviation of the substrate stage 16 acquired in this way and the deviation from the target position as shown in FIG. 7C, the relationship between the control deviation of the substrate stage 16 and the deviation from the target position is obtained. Can be obtained. Such processing is performed in advance of the exposure processing for each shot region of the substrate 15. Then, based on the relationship shown in FIG. 7C and the focus allowable value, a threshold value for compensating the measured value acquired at the measurement point 30 with respect to the control deviation of the substrate stage 16 is obtained.

In the process of exposing the substrate 15, first, while moving the substrate stage 16 in steps in the direction of the arrow F, the position in the height direction of the newly added measurement target portion 40h is measured at the measurement point 30 and the measured value. To get. At this time, the second position measurement unit 19 measures and acquires the control deviation of the substrate stage 16 when the position in the height direction of the measurement target portion 40h is measured at the measurement point 30. When the control deviation of the substrate stage 16 does not exceed the threshold value, _{the position of the shot region 15a 2 in} the height direction is determined based on the measured value of the measurement target portion 40h. Then, the substrate stage 16 is moved in the Z direction so that the _{shot region 15a 2} is located at the target position by the time the measurement point 30 reaches the measurement target point 40j.

Next, at the measurement point 30, the position in the height direction of the newly added measurement target location 40i is measured and the measured value is acquired. At this time, the second position measuring unit 19 measures and acquires the control deviation of the substrate stage 16 when the position of the measurement target portion 40i in the height direction is measured at the measurement point 30. When the control deviation of the substrate stage 16 does not exceed the threshold value, _{the position of the shot region 15a 2 in} the height direction is determined based on the measured value of the measurement target portion 40i. Then, the substrate stage 16 is moved in the Z direction so that the _{shot region 15a 2} is located at the target position by the time the measurement point 30 reaches the measurement target point 40j.

In the prior art, after the measurement point 30 reaches the measurement target point 40j, the position of the measurement target point 40j in the height direction is measured, and the substrate stage 16 is Z so _{that the shot area 15a 2 is located at the target position.} I'm moving in the direction. In the present embodiment, the position of the measurement target portion in the height direction is measured during the step movement, and the movement of the substrate stage 16 in the Z direction is started, so that the throughput can be improved. Further, the focus accuracy can be improved by determining whether or not to use the measured value of each measurement point according to whether or not the control deviation of the substrate stage 16 exceeds the threshold value.

Although the preferred embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to these embodiments, and various modifications and modifications can be made within the scope of the gist thereof.

100: Exposure device 12: Mask 15: Substrate 16: Substrate stage 17: Focus measurement unit 20: Control unit

Claims (9)

An exposure device that transfers a mask pattern to a substrate.
A stage that holds and moves the substrate,
Before the shot region of the substrate held on the stage reaches the exposure region where the shot region is exposed, the height direction of each of the plurality of measurement target locations including the first measurement target portion of the shot region. The first measurement unit that measures the position of and acquires multiple measured values,
By the shot area reaches the exposure area, and the position in the height direction of the shot area determined from the positions and the plurality of measured values of the stage measured by the position measuring unit for measuring the position of said stage Based on this, it has a control unit that controls the movement of the stage in the height direction so that the position in the height direction of the shot region is located at the target position.
The control unit
The control deviation of the stage in the height direction obtained from the position of the stage measured by the position measuring unit, and the position in the height direction of the shot area when the shot area reaches the exposed area. Based on the relationship with the deviation from the target position, the value of the control deviation of the stage at which the deviation becomes a predetermined value is obtained as a threshold value.
The control deviation of the stage in the height direction and the threshold value obtained from the position of the stage measured by the position measuring unit when the first measuring unit has acquired each of the plurality of measured values. based on the bets, the plurality of each exposure apparatus characterized by giving weights determine the position in the height direction of the shot area on the measured value. The threshold value, the exposure apparatus according to claim 1, characterized in that a threshold value for compensating the measured value obtained by the first measurement unit to the control deviation of the stage. Among the plurality of measured values, the control unit sets the weight given to the measured value obtained by the control deviation of the stage when the measured value exceeds the threshold value as zero, and sets the weight in the height direction of the shot region to zero. The exposure apparatus according to claim 1 or 2, wherein the position is obtained. When the control unit acquires the weight given to the measurement value in which the control deviation of the stage when the measurement value is acquired exceeds the threshold value among the plurality of measurement values. The exposure apparatus according to claim 1 or 2, wherein the control deviation of the stage is made smaller than the weight given to the measured value not exceeding the threshold value to obtain the position of the shot region in the height direction. It has a second measuring unit that measures the position of the first measurement target portion in the height direction and acquires a measured value when the shot region of the substrate held on the stage reaches the exposure region.
The control unit measures the position of the first measurement target portion in the height direction with the first measurement unit before the shot region is exposed, and the shot region is obtained from the first measurement value obtained. The movement of the stage in the height direction is controlled so that the position in the height direction of the shot region is located at the target position based on the position in the height direction of the shot region.
The second measured value acquired by measuring the position of the first measurement target portion in the height direction by the second measuring unit when the shot region reaches the exposed region, and the first measured value. The exposure apparatus according to claim 1 , wherein the difference is the deviation. The exposure apparatus according to any one of claims 1 to 5 , wherein the pattern of the mask is transferred to the substrate by exposing the substrate while scanning the mask and the substrate. The exposure apparatus according to claim 6 , wherein the plurality of measurement target locations include a second measurement target location in a region outside the shot region. The region outside the shot region includes a region that reaches the exposure region before the shot region reaches the exposure region.
The exposure apparatus according to claim 7 , wherein the plurality of measurement target locations include the plurality of second measurement target locations. A step of exposing a substrate using the exposure apparatus according to any one of claims 1 to 8.
The process of developing the exposed substrate and
A method for producing an article, which comprises the present invention and comprises producing an article from the developed substrate.

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