JP5379638B2 - Exposure apparatus, exposure method, and device manufacturing method - Google Patents

Description

  The present invention relates to an exposure apparatus, an exposure method, and a device manufacturing method.

  In a step-and-scan type exposure apparatus, the height of all shot areas is measured for the first substrate among a plurality of substrates to be exposed continuously (for example, included in the same lot). The amount of deviation (in the height direction) for each shot area is corrected during exposure. For the second and subsequent substrates among the plurality of substrates to be exposed continuously, only the height of the first shot area is measured, and the height of the first shot area of the first substrate is measured. The difference is reflected in other shot areas to correct the shift amount for each shot area during exposure. Several proposals have been made regarding such techniques (see Patent Documents 1 and 2).

JP 2003-203838 A JP-A-10-294257

  However, in the conventional technique, when a rotating component or a tilting component (that is, a substrate state) differs between a plurality of substrates to be exposed continuously, the components are not taken into consideration at the time of exposure. May cause. For example, consider a case where the second and subsequent substrates have undulations while the height of the first shot region of the second and subsequent substrates is the same as the height of the first shot region of the first substrate. . In such a case, in the prior art, since the difference between the height of the first shot area of the second and subsequent substrates and the height of the first shot area of the first substrate is zero, other shot areas The difference (that is, the appropriate difference corresponding to the swell) is not reflected on the. As a result, the exposure is performed without taking into consideration the actual rotation component and tilt component, which causes defocusing.

  In addition, defocus can be reduced by measuring the height of all shot areas and correcting the shift amount for each shot area for all of a plurality of substrates to be exposed continuously. Processing speed (throughput) is greatly reduced.

  Therefore, the present invention has been made in view of the problems of the conventional technique, and an object of the present invention is to provide a technique capable of reducing defocus while suppressing a decrease in throughput.

  In order to achieve the above object, an exposure apparatus according to one aspect of the present invention is an exposure apparatus including a projection optical system that projects a mask pattern onto a substrate, and a driving unit that drives a chuck that holds the substrate. A measurement unit that measures height at a plurality of measurement points in each of a plurality of shot regions on the substrate, and controls the height measurement at the plurality of measurement points by the measurement unit, and the drive unit A control unit that controls the driving of the chuck according to the above, wherein the control unit exposes the first to n-th (n is a natural number) substrates among a plurality of substrates to be continuously exposed. Controls the measurement unit to measure the heights of a plurality of measurement points in the region of the first number of shot regions among the plurality of shot regions on the nth substrate, and the measurement unit Is the height of multiple measurement points measured? The height of the shot area is determined, and the drive unit is controlled to position each of the plurality of shot areas on the nth substrate on the image plane of the projection optical system, In the case of exposing the (n + 1) th and subsequent substrates, a plurality of shot regions in the second number of shot regions smaller than the first number among the plurality of shot regions on the (n + 1) th and subsequent substrates are used. The measurement unit is controlled to measure the height of the measurement point, and corresponds to the second number of shot areas on the n + 1 and subsequent substrates among the plurality of shot areas on the nth substrate. The first plane is obtained from the heights of the plurality of measurement points in the shot area to be obtained, and the second plane is obtained from the heights of the plurality of measurement points in the second number of shot areas on the (n + 1) th and subsequent substrates. Seeking the plurality of shot areas For each of these, the shift amount in the height direction of the substrate between the first plane and the second plane is calculated, and the n determined from the heights of a plurality of measurement points measured by the measurement unit. Based on the height obtained by adding the amount of shift in the height direction of the substrate to the height of each of the plurality of shot regions on the first substrate, each of the plurality of shot regions on the n + 1 and subsequent substrates is The drive unit is controlled to be positioned on the image plane of the projection optical system.

  Further objects and other aspects of the present invention will become apparent from the preferred embodiments described below with reference to the accompanying drawings.

  According to the present invention, for example, it is possible to provide a technique for reducing defocus while suppressing a decrease in throughput.

It is a figure which shows the structure of the exposure apparatus as 1 side surface of this invention. FIG. 2 is a diagram for explaining control of a drive unit and a measurement unit by a control unit in the exposure apparatus shown in FIG. 1. In the exposure apparatus shown in FIG. 1, it is a figure which shows the relationship between the shot area on a plate, and the measurement point in the area | region of a shot area. 2 is a flowchart for explaining an exposure operation of the exposure apparatus shown in FIG. In the exposure apparatus shown in FIG. 1, it is a figure which shows the relationship between the shot area on a plate, and the measurement point in the area | region of a shot area.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings. In addition, in each figure, the same reference number is attached | subjected about the same member and the overlapping description is abbreviate | omitted.

  FIG. 1 is a view showing the arrangement of an exposure apparatus 1 as one aspect of the present invention. The exposure apparatus 1 is a projection exposure apparatus that transfers a mask pattern onto a large substrate such as a glass plate for a liquid crystal device by a step-and-scan method. In this embodiment, the exposure apparatus 1 should be continuously exposed. A plurality of substrates (eg, contained in the same lot) are exposed.

  The exposure apparatus 1 includes a projection optical system 10 that projects the pattern of the mask 23 onto the plate 36. A mask stage 20 is disposed on the object plane side of the projection optical system 10, and a plate stage 30 is disposed on the image plane side of the projection optical system 10. The mask stage 20 and the plate stage 30 can be driven independently, and their positions are measured by the laser interference length measuring device 50.

  The mask stage 20 includes a stage substrate 21 and an XYθ stage 22 disposed on the stage substrate 21, and holds the mask 23 via a chuck (not shown). Therefore, the mask stage 20 holds the mask 23 so that it can be driven in each of the X-axis direction and the Y-axis direction and can be rotated in the XY plane. Note that the X-axis direction and the Y-axis direction are orthogonal to each other. An observation optical system 42 for observing the mask 23 and the plate 36 is disposed above the mask stage 20 via the projection optical system 10, and illumination optics for illuminating the mask 23 is further above the observation optical system 42. A system 44 is arranged.

  The plate stage 30 includes a Y-axis stage 32, an X-axis stage 33, and a θZ stage 34 that are disposed on a stage surface plate 31. A chuck 35 that holds the plate 36 is disposed on the θZ stage 34. Therefore, the plate stage 30 holds the plate 36 so that it can be driven in each of the X-axis direction, the Y-axis direction, and the Z-axis direction and can be rotated in the XY plane. As will be described later, the chuck 35 is driven by a driving unit 60 and cooperates with the Y-axis stage 32, the X-axis stage 33, and the θZ stage 34 to expose the surface of the plate 36 (shot) when the plate 36 is exposed. (Region) is positioned on the image plane (focal plane) of the projection optical system 10.

  The laser interference length measuring device 50 includes a laser head 51, interference mirrors 52 and 53, a first reflection mirror 54 attached to the θZ stage 34, and a second reflection mirror 55 attached to the stage substrate 21. Including. The position of the laser light from the laser head 51 (the position of the projection optical system 10 in the optical axis direction) is set to the position of the object plane of the projection optical system 10 for the mask stage 20. On the other hand, for the plate stage 30, the position of the laser light from the laser head 51 (the position in the optical axis direction of the projection optical system 10) is set to a position displaced by a distance L from the position of the image plane of the projection optical system 10. The

  The measurement unit 70 is disposed between the projection optical system 10 and the plate 36 and measures the height at a plurality of measurement points in each of a plurality of shot regions on the plate 36. The control unit 80 includes a CPU and a memory, and controls the entire exposure apparatus 1 (operation). For example, the control unit 80 controls the height measurement at a plurality of measurement points in the shot region on the plate 36 by the measurement unit 70 and also controls the driving of the chuck 35 by the drive unit 60.

  With reference to FIG. 2, control of the drive unit 60 and the measurement unit 70 by the control unit 80 will be described. As described above, the plate 36 is held by the chuck 35. The measurement unit 70 includes, for example, four Z measurement sensors 71, 72, 73, and 74, measures the height of an arbitrary position (measurement point) on the plate 36, and outputs the measurement result (height). Input to the controller 80. The control unit 80 determines the height of the shot region from the input measurement result, and the driving amount of the plate 36 by the driving unit 60 necessary for the surface on the plate 36 to be positioned on the image plane of the projection optical system 10. And the control data including the drive amount is input to the drive unit 60. The drive unit 60 includes, for example, four actuators 61, 62, 63, and 64. The drive unit 60 drives the chuck 35 in accordance with control data input from the control unit 80, and the surface on the plate 36 of the projection optical system 10 is driven. Position it on the image plane.

  Here, the control in the case of exposing a plurality of plates to be continuously exposed in the exposure apparatus 1 will be described. In the present embodiment, each of the plurality of plates has six shot areas in which three shot areas are arranged in the row direction and two shot areas are arranged in the column direction (from the first shot area to the sixth shot area). It shall have.

  When the first plate of the plurality of plates is exposed, the control unit 80, as shown in FIG. 3A, four measurement points in the area of all the shot areas among the six shot areas. The measurement unit 70 is controlled to measure the heights of MP1 to MP4. Further, the control unit 80 determines the heights of the six shot areas on the first plate from the heights of the four measurement points MP1 to MP4 in each of the six shot areas. Then, the control unit 80 causes the driving unit 60 to position each of the six shot regions on the first plate on the image plane of the projection optical system 10 based on the height of each of the plurality of shot regions. The first plate is exposed while being controlled.

  When exposing the second and subsequent plates of the plurality of plates, the control unit 80, as shown in FIG. 3B, within the two shot regions at the end of the six shot regions. The measurement unit 70 is controlled to measure the heights of the four measurement points MP1 to MP4. The two shot areas at the end are shots in which a straight line connecting the two shot areas passes through the center of the plate or the vicinity thereof. In the present embodiment, the first shot area and the fourth shot area (1 Diagonal shot area of the second shot area). Next, the control unit 80 has four measurement points MP1 to MP1 in the first shot area and the fourth shot area on the first plate (corresponding to shot areas in which measurement points are measured in the second and subsequent plates). The first plane P1 is obtained (calculated) from the height of MP4. Similarly, the control unit 80 obtains (calculates) the second plane Pn from the heights of the four measurement points MP1 to MP4 in the first shot area and the fourth shot area on the second and subsequent plates. . Thus, the control unit 80 obtains the first plane P1 that is an approximate plane of the first plate and the second plane Pn that is an approximate plane of the second and subsequent plates. Next, for each of the six shot regions on the plate, the control unit 80 shifts the first plane P1 and the second plane Pn in the height direction of the plate (the first plane P1 and the second plane Pn). The difference from the plane P2 is calculated. In addition, the control unit 80 adds heights of the six shot regions on the first plate to the heights of the first plane P1 and the second plane Pn in the plate height direction. (That is, the height of each of the six shot areas on the second and subsequent plates) is calculated. Then, based on the respective heights of the six shot areas on the second and subsequent plates, the driving unit 60 is controlled so as to position each of the six shot areas on the image plane of the projection optical system 10. The second and subsequent plates are exposed.

  Here, an example of processing for calculating the first plane P1 and the second plane Pn from the height of each measurement point in the shot area on the plate will be described. Arbitrary plane P is defined as Z = Ax + By + C (Formula 1), and constants A, B, and C that minimize the square of the difference between the measurement result (height) Z and the arbitrary plane P at each measurement point are derived. To calculate an approximate plane.

  The measurement point (position) in the shot region on the plate is (xi, yi), and the measurement result (height) at the measurement point (xi, yi) is zi. Here, when i = 1 to n, the maximum number of measurement results is n. Further, when Expression 1 is expressed by a determinant, the following Expression 2 is obtained.

Here, constants A, B, and C that minimize Equation 1 are obtained from Equation 3 below, which is obtained by developing Equation 2, where D is the right-hand side matrix of Equation 2 and E is the left-side matrix. Note that D ^T represents a transposed matrix of the matrix D, and (D ^T D) ⁻¹ represents an inverse matrix of (D ^T D).

Further, the following equation 4 is defined using constants A, B, and C obtained from equation 3, and the shot region on the plate is substituted into equation 4 as (x _mn , y _mn ) as the center coordinates of the shot region. Each height can be calculated. Accordingly, it is possible to calculate the amount of displacement in the height direction of the plate between the first plane P1 and the second plane Pn (difference between the first plane P1 and the second plane P2). Here, m represents the number of plates, and n represents the number of the shot area on the plate.
Z _mn = Ax _mn + By _mn + C (Formula 4)
Hereinafter, with reference to FIG. 4, the exposure operation of the exposure apparatus 1 (that is, the process of exposing a plurality of plates to be continuously exposed) will be described. Note that this exposure operation is realized by the control unit 80 controlling the respective units of the exposure apparatus 1 in an integrated manner as described above. In addition, each of the plurality of plates has six shot areas, similar to the arrangement of shot areas shown in FIGS. 3 (a) and 3 (b).

  In S402, it is determined whether or not the plate carried into the exposure apparatus 1 and held on the plate stage 30 (chuck 35) is the first plate among the plurality of plates. If it is determined that it is the first plate, the process proceeds to S404, and if it is determined that it is not the first plate (that is, the second and subsequent plates), the process proceeds to S410. .

  In S404 (first measurement step), the heights of the measurement points (four measurement points MP1 to MP4) in each of all the shot areas among the six shot areas on the first plate are measured. To do. Note that the measurement results (heights) of the measurement points in each of the six shot areas on the first plate are stored in the memory of the control unit 80 or the like.

  In S406 (first exposure step), each of the six shot areas on the first plate is exposed. Specifically, the height of each shot area is determined from the height of the measurement points in each of the six shot areas, and each of the six shot areas on the first plate is projected onto the projection optical system 10. The first plate is exposed while being positioned on the image plane. The heights of the six shot areas on the first plate are stored in the memory of the control unit 80 or the like.

  In S408, the plate exposed in S406 is carried out of the exposure apparatus 1, and the next plate to be exposed (that is, the second and subsequent plates) is carried into the exposure apparatus 1, and the process proceeds to S402. .

  In S410 (second measurement step), the height of the measurement point in each of the first shot area and the fourth shot area is measured among the six shot areas on the second and subsequent plates. . Note that the measurement results (heights) of the measurement points in each of the first shot area and the fourth shot area on the second and subsequent plates are stored in the memory of the control unit 80 or the like.

  In S412 (first calculation step), a first plane P1, which is an approximate plane of the first plate, is calculated using the measurement result in S404. Specifically, the first plane P1 is calculated from the height of the measurement point in each of the first shot area and the fourth shot area on the first plate.

  Similarly, in S414 (second calculation step), a second plane Pn that is an approximate plane of the second and subsequent plates is calculated using the measurement result in S410. Specifically, the second plane Pn is calculated from the height of the measurement point in each of the first shot area and the fourth shot area on the second and subsequent plates.

  In S416 (third calculation step), for each of the six shot regions on the plate, the first plane P1 calculated in S412 and the second plane P2 calculated in S414 in the plate height direction. The amount of deviation is calculated.

  In S418 (second exposure step), each of the six shot areas on the second and subsequent plates is exposed. Specifically, the height obtained by adding the shift amount in the height direction of the plate calculated in S416 to the height of each of the six shot regions on the first plate determined from the measurement result in S404. Ask. Based on this height, the second and subsequent plates are exposed while positioning each of the six shot regions on the second and subsequent plates on the image plane of the projection optical system 10.

  In S420, it is determined whether or not the plate exposed in S418 is the last plate among the plurality of plates. If it is determined that it is the last plate, the process proceeds to S422, the plate exposed in S418 is carried out of the exposure apparatus 1, and the exposure operation is terminated. If it is determined that it is not the last plate, the process proceeds to S424, where the plate exposed in S418 is carried out of the exposure apparatus 1, and the plate to be exposed next is carried into the exposure apparatus 1. , The process proceeds to S402.

  As described above, the exposure apparatus 1 according to the present embodiment, when exposing the second and subsequent plates among the plurality of plates to be continuously exposed, the height of the measurement points in all the shot regions. Is not measured, but the height of the measurement point is measured within only a part of the shot area. Therefore, the exposure apparatus 1 has a processing speed (throughput) as compared with the case of measuring the heights of measurement points in all shot areas (that is, the heights of all shot areas) for all of the plurality of plates. The decrease can be suppressed. When the second and subsequent plates are exposed, the height difference between the first plane and the second plane in the height direction of the plurality of shot areas on the first plate is shifted. The height obtained by adding the amount is the height of each shot area of the second and subsequent plates. Therefore, even if the rotation component and tilt component (that is, the state of the substrate) differ between the plates to be continuously exposed, the component is taken into consideration at the time of exposure, and the data caused by the rotation component and tilt component of the plate. Focus can be reduced. Therefore, the exposure apparatus 1 can provide a high-quality device (liquid crystal device, semiconductor element, imaging element (CCD, etc.), thin film magnetic head, etc.) with high throughput and good economic efficiency. Such a device includes a step of exposing a substrate (glass plate, wafer, etc.) coated with a photoresist (photosensitive agent) using the exposure apparatus 1, a step of developing the exposed substrate, and other known steps. , Manufactured by going through.

  In the present embodiment, the first plane is calculated when the second and subsequent plates are exposed. However, when the first plate is exposed, the first plane is calculated and the control unit You may store in 80 memories. In the present embodiment, when the first plate is exposed, each shot area is exposed after measuring the heights of measurement points in the area of all shot areas on the plate. . However, measurement of the height of the measurement point in each shot area, such as measuring the height of the measurement point in the area of one shot area on the plate and exposing the one shot area, and such shot area These exposures may be repeated.

  Furthermore, in the present embodiment, the height of the measurement points in each of all shot areas is measured with the first plate, and within the areas of the two shot areas with the second and subsequent plates. The height of the measurement point is measured. However, even when the exposure operation of the exposure apparatus 1 is controlled as follows, a decrease in throughput can be suppressed as compared with the case where the heights of all shot areas are measured. Specifically, with respect to the nth plate (n is a natural number) from the top of the plurality of plates, the first number of shot regions in the plurality of shot regions on the nth plate are within the region of the first number of shot regions. Measure the height of the measurement point. Then, the height of the shot area is determined from the height of the measurement point in the first number of shot areas, and each of the plurality of shot areas on the nth plate is image plane of the projection optical system. The nth plate is exposed while being positioned at. On the other hand, with regard to the nth and subsequent plates of the plurality of plates, the measurement points in the second number of shot regions smaller than the first number among the plurality of shot regions on the nth and subsequent plates. Measure the height. Next, the first plane is calculated from the heights of the measurement points in the shot areas corresponding to the second number of shot areas on the (n + 1) th and subsequent plates among the plurality of shot areas on the nth plate. . Similarly, the second plane is calculated from the heights of the measurement points in the number of shot areas of the number of the platforms 2 on the (n + 1) th and subsequent plates. Then, the height obtained by adding the shift amount in the height direction of the plate between the first plane and the second plane to the height of each of the plurality of shot regions on the nth plate is set on the (n + 1) th plate. The (n + 1) th plate is exposed as the height of each of the plurality of shot regions. Note that the number of shot areas for measuring the height of the measurement point affects defocusing, so it must be set according to the allowable defocusing and the magnitude of the rotation component and tilt component existing on the plate. .

  Also, the measurement points in the shot area on the first plate and the measurement points in the shot areas on the second and subsequent plates cannot be arranged at the same position due to the layout or the like. Cases are also conceivable. For example, as shown in FIG. 5B, consider a case where only two measurement points MP5 and MP6 can be arranged in the region of the fourth shot region on the second and subsequent plates. In this case, as shown in FIG. 5 (a), two measurements in the fourth shot area on the second and subsequent plates are performed in the fourth shot area on the first plate. Two measurement points MP5 and MP6 corresponding to (the positions of) points MP5 and MP6 may be arranged. The first plane, which is an approximate plane of the first plate, is the measurement points MP1 to MP4 in the area of the first shot area on the first plate and the area of the fourth shot area. Is calculated from the measurement points MP5 and MP6. Similarly, the second plane which is an approximate plane of the second and subsequent plates is the measurement points MP1 to MP4 and the fourth shot area in the first shot area on the second and subsequent plates. It is calculated from the measurement points MP5 and MP6 in the region.

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

Claims (5)

An exposure apparatus including a projection optical system that projects a mask pattern onto a substrate,
A drive unit for driving a chuck for holding a substrate;
A measurement unit that measures the height at a plurality of measurement points in each of a plurality of shot areas on the substrate;
A control unit for controlling the height measurement at a plurality of measurement points by the measurement unit, and for controlling the driving of the chuck by the drive unit;
Have
The controller is
When exposing the first to n-th (n is a natural number) of the plurality of substrates to be exposed continuously, the first number of the plurality of shot areas on the n-th substrate is exposed. The measurement unit is controlled to measure the height of a plurality of measurement points in the shot region, and the height of the shot region is determined from the heights of the plurality of measurement points measured by the measurement unit. , Controlling the driving unit to position each of the plurality of shot areas on the nth substrate on the image plane of the projection optical system,
When exposing the n + 1st and subsequent substrates among the plurality of substrates, the second number of shot regions smaller than the first number among the plurality of shot regions on the n + 1st and subsequent substrates are exposed. The measurement unit is controlled to measure the heights of a plurality of measurement points in the region, and the second number on the n + 1 and subsequent substrates among the plurality of shot regions on the nth substrate. A first plane is obtained from the heights of a plurality of measurement points in the shot area corresponding to the shot area, and from the heights of the plurality of measurement points in the second number of shot areas on the (n + 1) th and subsequent substrates. A second plane is obtained, and a deviation amount in the height direction of the substrate between the first plane and the second plane is calculated for each of the plurality of shot regions, and a plurality of the measurement values measured by the measurement unit are calculated. The above determined from the height of the measurement point Based on the height obtained by adding the amount of shift in the height direction of the substrate to the height of each of the plurality of shot regions on the first substrate, each of the plurality of shot regions on the n + 1 and subsequent substrates is An exposure apparatus that controls the drive unit to be positioned on an image plane of the projection optical system.   2. The exposure apparatus according to claim 1, wherein the first number of shot areas includes all shot areas among a plurality of shot areas on the nth substrate. The second number of shot areas includes two shot areas at an end of a plurality of shot areas on the (n + 1) th and subsequent substrates,
3. The exposure apparatus according to claim 1, wherein a straight line connecting the two shot regions passes through the center of the n + 1 and subsequent substrates or in the vicinity thereof. An exposure method for exposing a substrate using an exposure apparatus provided with a projection optical system that projects a mask pattern onto the substrate,
First of measuring heights of a plurality of measurement points in a first number of shot areas among a plurality of shot areas on the first to nth substrates among a plurality of substrates to be exposed continuously. Measuring steps,
The height of the shot area is determined from the height of the plurality of measurement points measured in the first measurement step, and each of the plurality of shot areas on the nth substrate is an image of the projection optical system. A first exposure step of exposing the nth substrate while being positioned on a surface;
The height of a plurality of measurement points in a second number of shot areas less than the first number among the plurality of shot areas on the (n + 1) th and subsequent substrates among the plurality of substrates is measured. 2 measurement steps;
A first plane is calculated from the heights of a plurality of measurement points in a shot area corresponding to the second number of shot areas on the n + 1 and subsequent substrates among the plurality of shot areas on the nth substrate. A first calculating step for calculating;
A second calculation step of calculating a second plane from the heights of a plurality of measurement points in the second number of shot areas on the n + 1st and subsequent substrates;
Deviation in the height direction of the substrate between the first plane calculated in the first calculation step and the second plane calculated in the second calculation step for each of the plurality of shot regions. A third calculation step for calculating the quantity;
The amount of shift in the height direction of the substrate is added to the height of each of the plurality of shot areas on the nth substrate determined from the heights of the plurality of measurement points measured in the first measurement step. A second exposure step of exposing the n + 1st and subsequent substrates while positioning each of the plurality of shot areas on the n + 1st and subsequent substrates on the image plane of the projection optical system based on the height of ,
An exposure method comprising: Exposing the substrate using the exposure apparatus according to any one of claims 1 to 3,
Developing the exposed substrate;
A device manufacturing method characterized by comprising:

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