JP2010272673A - Exposure apparatus, and device manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exposure apparatus with improved throughput. <P>SOLUTION: The exposure apparatus exposes a substrate by projecting patterns of a first original plate and a second original plate. The apparatus has: an original-plate scanning means that is movable in the scanning direction while holding the first original plate and the second original plate in such a manner that they are arranged side by side in the scanning direction; a substrate scanning means that is movable in the scanning direction while holding a substrate; a lighting means for lighting the original plates; a projection means for projecting light from the original plates on the substrate; and a control means for controlling the original-plate scanning means, the substrate scanning means, and the lighting means. The control means controls the original-plate scanning means, the substrate scanning means, and the lighting means in the following manner. A first shot of the substrate is exposed via the first original plate in a first period during which the original-plate scanning means and the substrate scanning means are accelerated synchronously with each other. A second shot arranged in the scanning direction with respect to the first shot is exposed via the second original plate in a second period during which the original-plate scanning means and the substrate scanning means are decelerated synchronously with each other. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an exposure apparatus that exposes an original and a substrate while scanning the substrate.

  The exposure apparatus has been changed from a square field angle batch exposure method (stepper) to a scanning exposure method (scanner) in order to maximize the numerical aperture NA. The scanning exposure method is a method in which exposure is performed while scanning in the vertical direction while obtaining a horizontal width of an angle of view as a strip shape using an exposure area up to the maximum diameter that can be produced by a lens. In addition to being able to achieve a large angle of view that uses the maximum diameter of the lens by the strip exposure area, the scanning exposure method is fine, such as being able to continue focusing during scanning exposure and increasing the angle of view in the scanning direction. There are many advantages from the viewpoint of optimization.

  On the other hand, the productivity of the exposure apparatus has been improved along with the resolution. Generally, an index called CoO (Cost of Ownership) is used as a measure of productivity of production equipment. This is an index that represents the total cost for manufacturing one wafer. The price of the exposure apparatus, the number of wafers that the exposure apparatus can process per unit time, the running cost and operating rate of light sources, resist consumables, etc. It is calculated from these factors. In the exposure apparatus, in particular, how to improve the number of processed sheets per unit time is an important issue.

  The processing of the exposure apparatus is roughly divided into the following four factors (1) to (4) as wafer processing time. That is, (1) time for transporting the wafer and setting it on the stage, (2) time for observing the pattern on the wafer and determining its position, and (3) exposure by exposure light after moving the wafer to a predetermined position. (4) Time for unloading the wafer. Among these, the time occupying a large proportion is the time for performing the exposure of (3).

  Conventionally, a device for shortening the exposure time has been devised. In the scanning exposure apparatus, the shots (A, B) are sequentially exposed by the moving operation of the wafer stage, for example, in the order indicated by the broken-line arrows in FIG. In such an exposure apparatus, each shot is exposed while scanning (moving) the wafer stage from top to bottom or from bottom to top with respect to a strip-shaped exposure slit (exposure range of exposure light).

  The wafer stage accelerates immediately before each shot and continues to accelerate until a predetermined speed is reached. After reaching the vicinity of a predetermined speed, the wafer stage gradually changes its acceleration in a continuous function and shifts to a constant speed movement. Then, the exposure is started after waiting for stabilization of vibrations and the like caused by the acceleration change. After the exposure of the shot is completed, the rearrangement of scanning is performed, and the process proceeds to the exposure of the next shot. In this manner, the mask pattern is transferred to each shot on the wafer by so-called step-and-scan continuous operation.

  In order to shorten the step-and-scan operation, it was an important issue how to accelerate to a specified speed in a short time. For this reason, there existed big problems from a viewpoint of productivity and energy saving, such as enlargement of an actuator, increase in input energy, and increase in driving reaction force.

  In order to solve the above problem, Patent Document 1 discloses a configuration for reducing the number of step operations. The apparatus disclosed in Patent Document 1 performs exposure by continuously moving the wafer stage in one direction at a constant speed in order to reduce the number of times of acceleration and deceleration of the wafer stage. At that time, the exposure of the reticle stage is devised, and intermittent shots are provided in between to realize continuous exposure.

  Patent Document 2 discloses a configuration in which two reticles having the same pattern are mounted on a reticle stage and two shots are continuously exposed by one scanning operation. With such a configuration, the number of accelerations and decelerations can be reduced and the settling time can be shortened.

  Patent Document 3 discloses a configuration in which two reticle stages are provided and stepping stone exposure is performed with intermittent shots sandwiched between them. With such a configuration, throughput can be improved. An example of this is shown in FIG.

FIG. 8 is a diagram showing a velocity profile for driving the wafer stage. The wafer stage is accelerated until reaching the exposure speed V ₁₁ (t ₁₁ ), and after a fixed settling time t ₂₁ , the exposure is started when the speed deviation enters tolerance. After one shot is exposed (A, t ₃₁ ), the air travels as it is for one shot (t ₄₁ ), and the next one shot is exposed (B, t ₅₁ ). In conjunction with this profile of the wafer stage, the two reticle stages expose the first shot (A) with the first reticle and the next shot (B) with the second reticle while performing a synchronous scan.

JP 2000-21702 A JP 2005-203399 A JP 2007-27732 A

  Although the above-described conventional technology has a great effect on throughput improvement, the following problems remain.

  First, if two shots are continuously exposed in one scanning operation, the number of steps can be halved. However, in the first shot after the U-turn, the settling time is eliminated at the stage of shifting from acceleration to constant speed. I can't. Further, in order to quickly converge the vibration at the time of settling, it is necessary to take a reaction force process of the stage and a measure against vibration. In order to reduce the vibration itself, it is necessary to keep the natural vibration of the movable part high, which is expensive.

  In addition, a stage with high acceleration capability is required in order to achieve high speed with as short an acceleration as possible. For this reason, the maximum load of the actuator is set large, and it is necessary to increase the size of the stage and the power equipment. Furthermore, the time during which the intermittent shot between the two shots is idle is a waste time as it is and does not contribute to an improvement in throughput.

  The present invention provides, for example, an exposure apparatus that is advantageous in terms of throughput.

  An exposure apparatus according to an aspect of the present invention is an exposure apparatus that exposes a substrate by projecting a pattern of a first original plate and a second original plate, and scans the first original plate and the second original plate in a scanning direction. The original scanning means that can be moved in the scanning direction, the substrate scanning means that can move in the scanning direction while holding the substrate, the illumination means that illuminates the original, and the light from the original A projection unit that projects onto the substrate; and a control unit that controls the original scanning unit, the substrate scanning unit, and the illumination unit. The control unit synchronizes the original scanning unit and the substrate scanning unit with each other. A second period during which a first shot of the substrate is exposed through the first original plate during the first period of acceleration and the original plate scanning unit and the substrate scanning unit are decelerated in synchronization with each other; In the first shot The second shot of the substrate are arranged in the scanning direction for, to expose through the second original, the original scanning unit, and controls the substrate scanning means and the illuminating means.

  A device manufacturing method according to another aspect of the present invention includes a step of exposing a substrate using the exposure apparatus, and a step of developing the substrate exposed in the step.

  Other objects and features of the present invention are illustrated in the following examples.

  According to the present invention, for example, an exposure apparatus that is advantageous in terms of throughput can be provided.

FIG. 4 is a diagram showing a driving profile of a wafer stage at the time of scanning exposure in Example 1. 6 is a plan view showing a shot exposure order on a wafer in Embodiment 1. FIG. 1 is a schematic configuration diagram of a scanning exposure apparatus in Embodiment 1. FIG. In Example 1, it is a top view which shows the positional relationship of two reticles. 6 is a plan view showing a configuration of a reticle stage in Embodiment 2. FIG. FIG. 10 is a diagram showing a driving profile of a wafer stage in Example 2. In Example 3, it is a top view which shows the exposure order at the time of performing double exposure. It is a figure which shows the profile of the conventional wafer stage drive. It is a top view which shows the exposure order on the conventional wafer. It is a figure which shows the profile of the other wafer stage drive in a present Example. It is a figure which shows the profile of the other wafer stage drive in a present Example.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same members are denoted by the same reference numerals, and redundant description is omitted.

  The exposure apparatus in the present embodiment projects an original pattern onto a substrate via a projection optical system, and moves the original pattern and the substrate in synchronization with the optical axis of the projection optical system in synchronization with the original pattern. This is a scanning type exposure apparatus that exposes the light. The exposure apparatus of the present embodiment also has an original scanning unit capable of holding a plurality of originals (first original and second original), and exposing and transferring a plurality of original patterns on the substrate in a predetermined order. Is configured to do. Further, the original scanning unit moves in a predetermined acceleration state or a decelerating acceleration state during exposure.

Embodiment 1 of the present invention will be described below with reference to the drawings.
<Configuration of exposure apparatus>
First, the configuration of the exposure apparatus in the present embodiment will be described. FIG. 3 is a schematic block diagram of the scanning exposure apparatus 100 in the present embodiment.

  In FIG. 3, reference numeral 1 denotes an illumination system (illuminating means) including a light source that emits exposure light and an illumination optical system. The illumination system 1 is configured to illuminate the original (reticles 2 and 3). As the light source, for example, an excimer laser or an i-line lamp is used. The illumination optical system includes a beam shaping optical system that eliminates unevenness in illuminance distribution by oscillating the angle of coherent light, shapes the light beam shape, and makes it incoherent.

  Reference numeral 19 denotes an exposure slit that defines the irradiation range of the exposure light. Reference numerals 20 to 23 denote masking blades (light shielding plates) that dynamically define the exposure range of the shot start end and shot end at the time of scanning exposure.

  Reference numerals 2 and 3 denote reticles (first original plate and second original plate) on which a transfer pattern is formed. Reference numerals 4 and 5 denote reticle stages (original scanning means) that hold the reticles 2 and 3 and can move in the scanning direction. In this embodiment, a reticle stage 4 (first original stage) that holds the reticle 2 (first original plate) and a reticle stage 5 (second original stage) that holds the reticle 3 (second original plate). The two reticle stages are provided. However, the present invention is not limited to this, and both reticles 2 and 3 can be held by one reticle stage.

  Reference numerals 10 and 11 denote laser interferometers (position measuring means) for measuring the positions of the reticle stages 4 and 5. Reference numeral 12 denotes a laser interferometer (position measuring means) that measures the position of the wafer stage 8. The laser interferometers 10, 11, and 12 can accurately measure a long measurement span without contact.

  Light having pattern information transmitted through the reticles 2 and 3 is irradiated onto the wafer 7 (substrate) via the projection optical system 6. The wafer stage 8 (substrate scanning means) is placed on the base portion 13 and moves in the scanning direction while holding the wafer 7. The wafer 7 is scanned and exposed every predetermined shot while being held and fixed by the wafer stage 8.

Reference numeral 16 denotes a control device (control means). The control device 16 controls the reticle stages 4 and 5 as the original scanning unit, the wafer stage 8 as the substrate scanning unit, and the illumination system 1.
<Drive profile>
Next, a stage driving method in the scanning exposure apparatus 100 of the present embodiment will be described. FIG. 1 is a diagram showing a stage drive profile at the time of scanning exposure in the present embodiment.

  Of the two graphs shown in FIG. 1, the upper graph represents the Y-direction velocity profile of the wafer stage 8, and the lower graph represents the X-direction velocity profile of the wafer stage 8. In each graph, the vertical axis represents speed (Vy, Vx), and the horizontal axis represents time (time).

  FIG. 2 shows a shot exposure sequence on the wafer 7 in this embodiment. The exposure profile shown in FIG. 1 represents the operation of the wafer stage 8 shown in FIG. According to the profile of FIG. 1, as shown in FIG. 2, each shot is exposed in the order of A, B, B ′, A ′ as indicated by arrows (broken lines).

  In this embodiment, the reticle stages 4 and 5 can transfer and expose the pattern of two reticles 2 and 3 onto the wafer 7 by one operation that moves in one direction. Such multiple shots (A, B) are exposed with at least one or more intermittent shots.

As shown in FIG. 1, the wafer stage 8 starts to accelerate at a constant acceleration in the Y direction to expose the shot of A, and after the elapse of t ₁ hours, the reticle A starts from the moment when the Y speed v ₁ is reached. The exposure is started with the pattern. Thereafter, the exposure is continued while accelerating at a constant acceleration, and after the elapse of t ₂ hours, the exposure of the shot A is completed. Period performing exposure with the pattern of the reticle A (period t ₂₎ and the first period. Stage (wafer stage 8) also continues to accelerate as it after the first period, after a lapse of t _3/2 hours, it switched to the constant deceleration state.

  Since the exposure apparatus of the present embodiment shifts from the acceleration state to the deceleration state in such an intermediate idle time zone, a sufficient attenuation time can be ensured even if vibration occurs at that moment. For this reason, according to the exposure apparatus of the present embodiment, the throughput is not affected when the acceleration state is shifted. For this reason, additional elements and techniques for increasing vibration damping are not required.

  In addition, since the exposure apparatus of the present embodiment continues to accelerate constantly, the speed at the time of exposure can be increased even with a stage having a small acceleration force. For this reason, a high acceleration stage is not required. Therefore, high productivity can be achieved with a small actuator, that is, a small thrust.

  Further, since the vehicle travels at the maximum speed during idle running that passes intermittent shots, the idle running time can be significantly reduced.

Wafer stage 8, after t _3/2 hours elapsed after reaching the maximum speed (v _3), in order to expose the shot B, t ₄ hours only in the Y direction in a state of deceleration in the pattern of the reticle B Exposure. Period performing exposure with the pattern of the reticle B (period t ₄₎ and a second period.

  As described above, the control device 16 transfers the first shot of the wafer 7 via the reticle 2 (first original plate) in the first period in which the reticle stages 4 and 5 and the wafer stage 8 are accelerated in synchronization with each other. To control the exposure. Further, the control device 16 applies the second shot of the wafer 7 arranged in the scanning direction with respect to the first shot to the reticle 3 in the second period in which the reticle stages 4 and 5 and the wafer stage 8 are decelerated. Control is performed so that exposure is performed via (second master).

  Such control by the control device 16 is performed on the reticle stages 4 and 5, the wafer stage 8, and the illumination system 1. As will be described later, the second shot of the wafer 7 has an interval of one shot or more in the scanning direction with respect to the first shot.

  After the exposure of the B shot is completed, the wafer stage 8 proceeds to the U-turn operation process for the adjacent B ′ shot exposure. Since the U-turn operation for the B 'shot is a rearrangement operation, not only the Y speed but also the X speed change. The profile is as shown in the lower part of FIG.

Immediately after the end of the B shot exposure, the wafer stage 8 accelerates and decelerates in the X direction and moves a distance corresponding to the X size of the shot. The movement time t _{6 in the} X direction is preferably at least t ₅ × 2 or less.

Next, a procedure for determining this profile will be described. First, in order to determine the profile, the shot size in each of the X and Y directions is set to (L _x , L _y ), the exposure slit width S, and the maximum acceleration of the wafer stage 8 is set to each of the X and Y directions (α _x , α _y ). Give as. At this time, the time required for the X step (X-direction movement time t ₆ ) is expressed by Expression (1).

Here, ε is a stage settling time required at the X step.
Run-up times _{t 1} and _{t 5} in the Y _step, since it is sufficient _t 6/2 or more, when these times _t 1, _{t 5} is equal to the _t 6/2, is expressed by equation (2) The

Further, the exposure times t ₂ , t ₃ , and t ₄ of the A shot are expressed as equations (3), (4), and (5), respectively.

Next, the velocities v ₁ , v ₂ , and v ₃ shown in FIG. 1 are expressed as equations (6), (7), and (8), respectively.

  As described above, each time and each speed are uniquely obtained as in the equations (1) to (8). Therefore, a driving profile can be generated as shown in FIG. In this embodiment, a profile indicating the relationship between speed and time is obtained. However, a profile showing the relationship between the position function and time, or a control function and time obtained by calculation from these, are obtained in the same procedure. It is also possible to generate a profile indicating the relationship.

Here, the effect of the present embodiment is quantitatively estimated. The stage accelerations α _x and α _y are both 9.8 m / s ² , the shot size is L _y = 0.03 m, L _x = 0.02 m, and the slit width is 0.005 m. For simplicity, the settling time ε is assumed to be zero.

Substituting these values into equation (1) to (8), when determining the time _{t 1, t 2, t 3} /2,
t ₁ = 0.045 [sec]
t ₂ = 0.051 [sec]
t ₃ /2=0.006 [sec]
It becomes. After calculating the one-shot exposure time t _a using these values,
t _a = 0.102 [sec]
It becomes.

For example, when the one wafer to 100 shots exposure, be added other dead time of 5 seconds to time 100 × t _a, it is possible to complete the exposure process in 15.2 seconds.

Next, when the same calculation is performed in the conventional example shown in FIG. 8 to calculate the exposure time t _a ′ for one shot,
t _a ′ = 0.152 [sec]
It becomes. Therefore, in order to process one wafer in the conventional example, it takes time _{100 × t a '+ 5 =} 20.2 seconds. When the method of the present embodiment is compared with the method of the conventional example, the processing time is reduced by about 25%.

  In the present embodiment, as shown in FIG. 1, the wafer stage speed during exposure is in a state of constant acceleration or a state of constant deceleration acceleration. However, it is not limited to this. The present embodiment may be any profile that performs exposure while changing the speed, and a profile other than that shown in FIG. 1 can also be adopted.

As another example of performing exposure while changing the speed, there are profiles shown in FIGS. 10A and 10B. FIG. 10A is a profile for driving the A shot and the B shot at continuous equal additive speeds. FIG. 10B is a profile partially including a constant velocity region during A-shot and B-shot exposure. In the present embodiment, even when the profiles as shown in FIGS. 10A and 10B are adopted, the same effect as the profile of FIG. 1 can be obtained.
<Control of exposure amount>
Next, the exposure amount control in the present embodiment will be described.

  In this embodiment, the speed of the wafer stage changes during exposure. For this reason, there is provided an adjusting means for changing the exposure illuminance (exposure light intensity) according to the speed of the wafer stage so as to keep the exposure amount irradiated to any one point of the photosensitive resist coated on the wafer constant. It is necessary to provide it. This adjustment means changes the intensity of the exposure light in proportion to the speed of the wafer stage, for example. Hereinafter, a method using a pulse light source such as an excimer laser will be described. However, the present embodiment is not limited to this.

  When the pulse energy amount emitted individually is constant, the accumulated exposure amount P irradiated on the wafer is expressed by the following equation (9).

Here, q is an exposure amount accumulated by pulse emission per time, f is a pulse emission frequency, S is a slit width, and _Vy is a scanning speed in the Y direction. From equation (9), in order to make the accumulated exposure amount P constant, the exposure amount q or the pulse emission frequency f may be changed according to the scanning speed V _y .

  Assuming that the exposure q is constant, the pulse emission frequency f is calculated as follows:

It becomes.

  Further, assuming that the pulse emission frequency f is constant, the exposure amount q accumulated by one pulse emission is obtained,

It becomes.

As means for making the exposure amount q variable, it is sufficient to change the light emission energy or insert an illuminance adjustment mechanism using a neutral density filter. In addition, the above equations (10) and (11) are all functions of the wafer stage scanning speed V _y , but are not limited thereto. For example, a position function or time function of the wafer stage, or a control function obtained from them may be adopted.

Thus, in this embodiment, even when exposure is performed while accelerating or decelerating the wafer stage by providing an adjusting means (control device 16) that changes the exposure amount q (exposure light intensity) or the pulse emission frequency f. It is possible to perform exposure with a uniform accumulated exposure amount.
<Structure of reticle stage>
Next, a detailed configuration of the reticle stage in the present embodiment will be described.

  As shown in FIG. 3, a reticle stage 4 (first reticle stage) and a reticle stage 5 (second reticle stage) are provided on a base portion 9 having a reticle stage guide surface and a reticle stage drive mechanism. , Is placed on a common guide surface. The positions of the reticle stages 4 and 5 are measured by laser interferometers 10 and 11 as position measuring means for measuring a relative position with respect to the projection optical system 6 (lens barrel).

  Based on the position information measured by the laser interferometers 10 and 11, the control device 16 performs a calculation. Each of the reticle stages 4 and 5 is driven by a base unit 9 (stage driving unit) based on information output from the control device 16.

  The position measuring means (laser interferometers 10 and 11) measures the reticle stages 4 and 5 from different directions. However, the present embodiment is not limited to this, and the position measuring unit may be configured to measure each of the reticle stages 4 and 5 from the same direction. Furthermore, another measuring means may be provided that measures the reticle stage 5 with the first position measuring means (laser interferometer 10) and measures the reticle stage 4 with reference to the position of the reticle stage 5. As another configuration example, instead of the reticle stage, a measuring unit that directly measures the position of the reticle end surface may be provided.

  Above each of the reticle stages 4 and 5, a reticle transport system 18 for mounting and transporting the reticles 2 and 3 is provided. The reticle transport system 18 carries and places the reticles 2 and 3 at predetermined positions on the reticle stages 4 and 5, respectively. The reticle measurement system 17 performs various measurements related to the positional deviation of the reticles 2 and 3, the flatness of the reticles 2 and 3, deflection and deformation in the holding state, the difference in height between the two reticles 2 and 3, and the like. .

  Next, the scanning operation of the reticle stages 4 and 5 will be described.

  In order to expose the A shot shown in FIG. 2 with the reticle 2, the reticle stage 4 moves while accelerating the stage movable range of FIG. 3 from the left to the right (arrow direction). At this time, the reticle stage 5 is also accelerated at the same time while maintaining a certain distance D from the reticle stage 4.

  After the A shot is exposed in the uniform acceleration state, the two reticle stages 4 and 5 shift to the deceleration acceleration, and the B shot is exposed with the reticle 3 as it is. Thereafter, the two reticle stages 4 and 5 reach zero speed in the constant deceleration acceleration state, and proceed to the acceleration process in the reverse direction. In the meantime, the wafer stage 8 changes the row, and this time, the B 'shot is exposed with the reticle 3 in the equal acceleration state. Thereafter, the A ′ shot is exposed with the reticle 2 in the deceleration acceleration state.

  As described above, the control device 16 sequentially exposes the first shot through the reticle 2 and the second shot through the reticle 3, and then rearranges the third shot through the reticle 3. And the fourth shot through the reticle 2 are controlled to be exposed in order.

  FIG. 4 is a plan view showing the positional relationship between the two reticles 2 and 3 in this embodiment.

In FIG. 4, the interval D represents the distance between the end of the pattern drawn on the reticle 2 and the end of the pattern drawn on the reticle 3. The value of the distance D, it is preferable to set at least one shot size L _y sandwiched A shot and B shots equal size divided by the projection magnification M (for example, 1/4) shown in FIG. 2 .

In this embodiment, the two reticle stages 4 and 5 perform acceleration / deceleration scanning movements as if they were one reticle stage while maintaining the distance D. In this embodiment, although to be identical to shot size L _y apart D, but is not limited thereto. Integral multiple (2 times, 3 times, etc.) of the shot size L _y the distance D may be set to.

  Further, two reticles 2 and 3 may be mounted on one reticle stage so that the distance D can be maintained. In this case, it is desirable to provide a moving mechanism on the reticle stage that can change the distance between the two reticles.

In this embodiment, the reticle stage is moved while the interval D is always kept constant. However, the reticle stages 4 and 5 may be synchronized with the wafer stage 8 only during the exposure times t ₂ and t ₄ . For this reason, the space | interval D does not need to always be maintained constant. As long as various conditions regarding exposure are satisfied, the individual reticle stages 4 and 5 can individually determine drive profiles.
<Wafer exposure order>
Next, exposure on the wafer will be described with reference to FIG.

  An array of shots to be exposed on the wafer is n rows × m columns. In this embodiment, exposure is sequentially performed while changing the nth and n + 2th rows from the bottom of the shot in the + X direction. Next, exposure is performed sequentially while changing the n + 1th row and the n + 3th row in the −X direction. Thereafter, n is replaced with n + 4, and exposure is performed in the same manner as described above.

  Since the wafer is circular, there are missing shots on the outer periphery. With respect to this short shot, the light emission can be stopped and the idle driving operation can be performed. Further, in the short shot, exposure may be performed by the operation of only one reticle stage as in the prior art.

The exposure apparatus according to the present embodiment is configured to perform exposure by skipping over one line. However, when the shot size is small, the exposure apparatus may be set so as to jump over two lines.
<Operation of shading plate>
Next, the operation of a light shielding plate (masking blades 20 to 23) that shields illumination light in accordance with scanning will be described.

  The exposure apparatus according to the present embodiment includes two pairs of masking blades 20 to 23 corresponding to the reticle stages 4 and 5 in order to expose the two reticles 2 and 3. The two pairs of masking blades 20 to 23 are respectively driven at a speed corresponding to the profile of the stage. The two pairs of masking blades are arranged so as to be as close to the light shielding surface as possible, so that the blade edges face each other back to back so that they are substantially flush with each other.

The masking blades 22 and 23 are provided for shielding the edge of the reticle 2, and the masking blades 20 and 21 are provided for shielding the reticle 3. The masking blades 20 to 23 are driven in the Z direction in conjunction with the scanning operations of the reticles 2 and 3.
<Correction between reticle differences>
Next, a method for reducing the difference between reticles generated by using two reticles will be described.

  In the case of exposing two reticles 2 and 3 having the same pattern information, the factors that degrade the accuracy are reticle deflection, reticle stage height error, and reticle drawing error. All of these factors appear as defocus, magnification error, one-sided blur, and distortion as a result of exposure.

  In this embodiment, the reticle measurement system 17 can measure the flatness and deflection of the two reticles 2 and 3 and the height of the reticle stages 4 and 5. Further, the pattern measurement sensor 14 mounted on the wafer stage 8 is irradiated with reticle transmission light, so that the drawing error of the two reticles 2 and 3 can be directly measured.

Information on the individual reticles 2 and 3 measured as described above is processed by the control device 16. Based on the measurement information, the control device 16 performs correction such as offsetting the positions of the reticle stages 4 and 5 as necessary, and correcting the reticles 2 and 3 by directly applying a correction force. In addition, the control device 16 instructs the lens correction device 15 to move the correction lens inside the projection optical system 6 (projection lens). Further, the control device 16 can correct the reticle difference by correcting the position information of the wafer stage 8.
<Acceleration / deceleration correction>
Next, correction performed at the time of acceleration / deceleration in the exposure apparatus of the present embodiment will be described.

  In this embodiment, since exposure is performed in a uniform acceleration state, a constant inertia force acts on the movable portion. Due to this inertial force, each part is deformed, and this deformation becomes an error factor. Examples of large influences of deformation include a bar mirror, a wafer stage top plate structure, a reticle stage top plate structure, and the reticle itself, which serve as a position reference for the wafer stage 8.

  The functions representing these deformations are functions that depend on acceleration, and also depend on stage coordinates, reticle stage selection, scanning direction, and the like. Therefore, in this embodiment, means for switching correction values according to conditions using a plurality of correction tables is provided.

  First, the correction table is created with X and Y functions of wafer coordinates. The plurality of correction tables are respectively created according to each condition such as which one of the reticle stages 4 and 5 is used for exposure, whether the scanning direction is + Y or −Y, acceleration exposure or deceleration exposure.

  The control device 16 (control system) selects a correction table that matches the exposure conditions, multiplies the correction table by acceleration, and generates a correction value. In the present embodiment, a plurality of correction tables are created, but correction values may be generated by a function calculation using a mathematical formula that takes into account the respective correction conditions.

  In the present embodiment, the speed during scanning exposure is sufficiently high and sequentially changes. For this reason, it is necessary to consider the light transmission delay time until the light transmitted through the reticle reaches the wafer. In the calculation based on the above estimation, the initial speed at the start of exposure is 0.44 m / s and the final speed is 0.94 m / s. The wafer stage produces a speed change of 0.5 m / s during that time. As a result, a position shift of about 1.7 nm occurs between the start point and the end point of the shot while the light passes through the lens corresponding to the air interval of about 1 m.

Therefore, in the above-described correction function or correction table, it is desirable that the correction value is a speed function of the wafer stage, and an offset value depending on the speed is added to the position command value in the scanning direction.
<Storing and sweeping exposure information>
According to the exposure method of the present invention, the wafer is exposed under the following conditions: (1) A reticle / B reticle, (2) accelerated exposure / decelerated exposure, and (3) up direction scanning / down direction scanning. Shots are mixed. Although the error due to this condition difference is minimized by the above-described correction, it cannot be made completely zero.

  Therefore, in this embodiment, as shown in FIG. 7, there are means for storing and saving these conditions in the control device 16 as history information of each shot, and means for transferring the history information outside the device. Based on this information, it is possible to perform alignment, overlay and inspection in consideration of shot conditions in the subsequent process.

  Next, a second embodiment of the present invention will be described.

  FIG. 5 is a plan view showing the configuration of the reticle stage in the present embodiment. As shown in FIG. 5, in this embodiment, three reticle stages 41, 42, 43 and three reticles 31, 32, 33 are provided.

  FIG. 6 is a diagram showing a driving profile of the wafer stage in the present embodiment. As shown in FIG. 6, the driving of the wafer stage in this embodiment is divided into three stages. First, at time A, equal acceleration exposure is performed on the reticle stage 41 (first reticle stage). Next, after skipping one shot intermittent shot, at time B, exposure with zero acceleration (constant velocity) is performed on the reticle stage 42 (second reticle stage). Finally, after skipping one shot intermittent shot, at time C, deceleration acceleration exposure is performed on the reticle stage 43 (third reticle stage).

  In the present embodiment, the number of reticle stages is not limited to three, and four or more reticle stages may be used. Even if exposure is performed using four or more reticles and four or more reticle stages, the same effect as described above can be obtained.

  Next, Embodiment 3 of the present invention will be described.

  The exposure apparatus of the present embodiment performs double exposure with two reticles (first reticle and second reticle) having different pattern information. In the double exposure, the second reticle exposure is superimposed on the exposure with the first reticle.

  FIG. 7 is a plan view showing an exposure order when performing double exposure in this embodiment.

  In a shot arrangement of n rows × m columns on a wafer, first, from the bottom to the second row are first exposed with a first reticle (here, a B reticle). Thereafter, in the same manner as in the first embodiment, intermittent shots are placed between the two reticle stages, and acceleration / deceleration exposure is performed with a stepping stone, so that the pattern of the A reticle is superimposed on the pattern of the B reticle. Unlike the first embodiment, each shot is exposed twice while a line feed is performed line by line.

  Next, the operation of the exposure apparatus when exposing two types of reticle patterns will be described in more detail.

  In general, one of the patterns split by double exposure is a pattern mainly composed of vertical lines, and the other is a pattern mainly composed of horizontal lines, or different exposure patterns such as critical lines and trim lines. . For this reason, it is necessary to select the optimal illumination light conditions and the numerical aperture of the lens according to such a pattern.

In this embodiment, there is switching means for switching the illumination mode and the numerical aperture during a short time t1 + t5, t3 in the gap between two reticle exposures. By switching the illumination mode and numerical aperture with this switching means, the optimum illumination mode and numerical aperture can be selected.

Next, a method for manufacturing a device (semiconductor device, liquid crystal display device, etc.) according to an embodiment of the present invention will be described. In this method, an exposure apparatus to which the present invention is applied can be used.

  A semiconductor device is manufactured through a pre-process for producing an integrated circuit on a wafer (semiconductor substrate) and a post-process for completing the integrated circuit on the wafer produced in the pre-process as a chip product. The pre-process can include a step of exposing the wafer coated with the photosensitive agent using the exposure apparatus described above, and a step of developing the wafer exposed in the step. The post-process can include an assembly process (dicing, bonding) and a packaging process (encapsulation). Moreover, a liquid crystal display device is manufactured by passing through the 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 exposure apparatus, and the step And a step of developing the glass substrate exposed in step (b). The device manufacturing method of this embodiment is more advantageous than the conventional one in at least one of device performance, quality, productivity, and production cost. The exposure apparatus of each of the above embodiments can be applied to an exposure apparatus for manufacturing a MEMS element, an imaging element, a magnetic head, etc., in addition to a semiconductor integrated circuit element and a liquid crystal display element.

  As described above, according to the exposure apparatus of each of the embodiments, it is possible to perform scanning exposure without requiring stage settling time and without causing a vibration that becomes a problem during exposure, so that both high accuracy and high throughput can be achieved. Is possible. In addition, a high throughput can be obtained even with a small thrust stage, which contributes to cost reduction of the apparatus. Therefore, according to each of the above embodiments, an exposure apparatus with improved throughput can be provided.

  The embodiment of the present invention has been specifically described above. However, the present invention is not limited to the matters described as the above-described embodiments, and can be appropriately changed without departing from the technical idea of the present invention.

1: illumination system 2, 3: reticle 4, 5: reticle stage 6: projection optical system 7: wafer 8: wafer stage 16: controller 100: scanning exposure apparatus

Claims (8)

An exposure apparatus for exposing a substrate by projecting a pattern of a first original plate and a second original plate,
An original plate scanning means that holds the first original plate and the second original plate side by side in a scanning direction, and is movable in the scanning direction;
Substrate scanning means that holds the substrate and is movable in the scanning direction;
Illuminating means for illuminating the original plate;
Projection means for projecting light from the original plate onto the substrate;
Control means for controlling the original scanning means, the substrate scanning means and the illumination means,
The control means exposes the first shot of the substrate through the first original plate in a first period of accelerating the original plate scanning means and the substrate scanning means in synchronization with each other, and In a second period in which the original scanning unit and the substrate scanning unit are decelerated in synchronization with each other, the second shot of the substrate arranged in the scanning direction with respect to the first shot is changed to the second shot An exposure apparatus that controls the original scanning unit, the substrate scanning unit, and the illuminating unit so that exposure is performed through the original.   The exposure apparatus according to claim 1, wherein the second shot has an interval of one shot or more in the scanning direction with respect to the first shot.   3. The original plate scanning unit includes a first original stage that holds the first original plate and a second original stage that holds the second original plate. Exposure equipment.   The control means sequentially exposes the first shot through the first original plate and the second shot through the second original plate, then rearranges the second shot, 4. The exposure apparatus according to claim 1, wherein control is performed so that a third shot is exposed through the first master and a fourth shot is exposed through the first original plate in order. 5. .   The control means performs control so that the original scanning means and the substrate scanning means are accelerated at a constant acceleration in the first period and decelerated at a constant acceleration in the second period. An exposure apparatus according to any one of claims 1 to 4.   6. The illumination unit according to claim 1, wherein the illumination unit includes an adjustment unit that adjusts an intensity of illumination light according to a speed of at least one of the original plate scanning unit and the substrate scanning unit. Exposure device. The pattern of the first original plate and the pattern of the second original plate are different from each other,
The control means exposes the shot through the other of the first original plate and the second original plate after exposing the shot through one of the first original plate and the second original plate, The exposure apparatus according to claim 1, wherein the original scanning unit, the substrate scanning unit, and the illumination unit are controlled. 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: