JP2010283243A - Exposure apparatus and device manufacturing method - Google Patents

Abstract

【Task】
For example, an exposure apparatus that is advantageous in terms of overlay accuracy even when the temperature distribution of the wafer is non-uniform is provided.
[Solution]
An exposure apparatus that measures the positions of a plurality of sample shots on a substrate, calculates an array of shots based on the measured positions, positions each shot according to the calculated array, and exposes the substrate. Measuring means for measuring the temperature distribution of the surface of the surface, and specifying a partial area of the surface based on the temperature distribution measured by the measuring means, selecting a plurality of sample shots for the partial area, and selecting A control unit that calculates an arrangement of shots based on measured positions of the plurality of sample shots.
[Selection] Figure 5

Description

  The present invention relates to an exposure apparatus that measures the positions of a plurality of sample shots on a substrate, calculates an array of shots, positions each shot according to the calculated array, and performs exposure.

Conventionally, alignment of wafers (substrates) (for example, alignment with respect to an original plate) is performed by measuring the amount of misalignment of alignment marks in a plurality of sample shots (deviation amount with respect to a design position), and arranging (positioning) all shots It was done by calculating. For example, parameters (shift, magnification, rotation angle, etc.) representing the positional deviation of the entire pattern (shot) formed on the wafer are calculated, and the wafer is aligned based on the calculated parameters.
In recent years, the overlay accuracy required for an exposure apparatus has increased, and the nonlinear component of the measured mark misregistration amount cannot be ignored. For this reason, zone alignment measurement is proposed in which the wafer surface is divided into a plurality of partial areas, and the position of the sample shot is measured for each partial area to calculate the shot arrangement (Patent Document 1).

Japanese Patent Laid-Open No. 2003-324055

The non-linear component exists roughly depending on whether the pattern on the wafer is originally formed non-linearly or due to non-uniform temperature distribution of the wafer in the exposure apparatus.
An object of the present invention is to provide an exposure apparatus that is advantageous in terms of overlay accuracy even when, for example, the temperature distribution of a wafer is not uniform.

  An exposure apparatus of the present invention for solving the above problems measures the positions of a plurality of sample shots on a substrate, calculates an array of shots based on the measured positions, and sets each of the shots according to the calculated array. An exposure apparatus that positions and exposes a shot, the measuring means for measuring the temperature distribution of the surface of the substrate, and the partial region of the surface is specified based on the temperature distribution measured by the measuring means, And a control unit that selects a plurality of sample shots with respect to the partial region and calculates an arrangement of the shots based on the measured positions of the selected sample shots.

  According to the present invention, for example, an exposure apparatus that is advantageous in terms of overlay accuracy can be provided even if the temperature distribution of the wafer is not uniform.

Hereinafter, an exposure apparatus according to a first embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view of an exposure apparatus for semiconductor manufacturing according to Embodiment 1 of the present invention.
The exposure apparatus of the first embodiment measures the positions of a plurality of sample shots 408, 409, 410, and 411 on the wafer 105 (substrate) shown in FIG. Furthermore, an array of shots 415 is calculated based on the measured position, and each shot 415 is positioned and exposed according to the calculated array. The reticle 101 is an original plate on which a semiconductor element manufacturing pattern 102 is formed. The projection optical system 103 is an optical system that projects the pattern 102 on the reticle 101 on the wafer 105 (substrate) on the XYθ stage 104 in a reduced scale. The control unit 106 is a control unit that controls the entire exposure apparatus. The console 107 is a part that inputs necessary information such as alignment data and exposure data to the control unit 106 and stores them in a storage device such as a built-in hard disk. The control unit 106 includes a plurality of computers, a memory, an image processing device, an infrared thermography device, an XYθ stage control device, and the like.

  Reticle 101 is sucked and held by reticle stage 108 that moves in the X, Y, and θ directions in accordance with a command from control unit 106. Reticle 101 has reticle alignment marks 109R and 109L and reticle marks 111R and 111L. Reticle alignment marks 109 </ b> R and 109 </ b> L are alignment marks used when aligning reticle 101 with projection optical system 103 in a predetermined positional relationship. Reticle marks 111R and 111L are marks for transferring to photochromic plate 110. In the exposure apparatus of the first embodiment, the reticle marks 111R and 111L are arranged on the reticle 101 at the same Y coordinate position.

  Reticle set marks 112R and 112L are formed on a member fixed to the barrel of projection optical system 103 so as to have a predetermined positional relationship with respect to projection optical system 103. The alignment of the reticle 101 with respect to the projection optical system 103 images the following two sets. That is, the imaging device 114 superimposes images of the set of the reticle alignment mark 109R and the reticle set mark 112R and the set of the reticle alignment mark 109L and the reticle set mark 112L via the mark observation mirrors 113R and 113L. Further, the reticle stage 108 is moved so that the positional deviation amount detected from the image output at this time is within a predetermined allowable value. The mark observation mirrors 113 </ b> R and 113 </ b> L can be moved in the X and Y directions by a command from the control unit 106.

  The motors 115X and 115Y are motors that move the XYθ stage 104 in the XY directions. Mθ (not shown) is a motor that rotates the XYθ stage 104 in the θ direction. Reference numerals 116X and 116Y denote mirrors fixed to the XYθ stage 104. The position of the XYθ stage 104 on the XYθ coordinate is constantly monitored by the laser interferometers 117X, 117Y, and 117θ and the mirrors 116X and 116Y. The XYθ stage 104 is further moved to a position commanded from the control unit 106 by the motors 115X and 115Y. The control unit 106 holds the XYθ stage 104 at a specified position based on the outputs of the laser interferometers 117X, 117Y, and 117θ even after the movement of the XYθ stage 104 is completed.

  The wafer stage 118 is a wafer holding stage that moves in the Z direction with respect to the XYθ stage 104, and the wafer 105 is held by suction on the wafer stage 118. The photochromic plate 110 is a flat plate coated with a photosensitive agent (for example, a spiropyran-based or spironaphthoxazine-based photochromic material) fixed on the XYθ stage 104 or the wafer stage 118, and has a high imaging surface of the projection optical system 103. It is provided in the vicinity. The transmittance of the photosensitizer temporarily changes with respect to light having an exposure wavelength from the exposure light source 119, and returns to the original transmittance with time. Therefore, the mark on the reticle 101 can be transferred, and after a certain time, the transferred pattern disappears and the mark can be transferred again.

  The exposure light source 119 is a light source for projecting and exposing the pattern 102 on the reticle 101 onto the wafer 105 on the wafer stage 118 via the projection optical system 103. The exposure light source 119 is also used as a light source when projecting and exposing the reticle marks 111R and 111L onto the photochromic plate 110 via the mark observation mirrors 113R and 113L and the projection optical system 103 by opening the mark exposure shutters 120R and 120L. The

  The off-axis scope 121 is a mark observing microscope having a focal plane at a heel position substantially equal to the projection optical system 103. The off-axis scope 121 captures an image of the mark transferred onto the wafer 105 or the photochromic plate 110 on the wafer stage 118. Based on the image output at this time, the control unit 106 calculates the distance that the captured mark is displaced from the center of the off-axis scope 121 in the XY direction. Measuring this shifted distance is referred to as baseline measurement. That is, the baseline measurement is to measure the distance (deviation) in the XY plane between the shot center position when aligning the wafer 105 and the shot center position during exposure (the optical axis position of the projection optical system 103). It is.

There are various baseline measurement methods, and a method using a photochromic plate is used in the first embodiment.
Although omitted in the following description, when the pattern 102 on the reticle 101 is aligned and transferred to the shot 415 on the wafer 105, the amount of deviation measured by the baseline measurement is reflected. The off-axis scope 121 can change the magnification. At the time of pre-alignment mark measurement described later, the off-axis scope 121 is switched to a low magnification to detect the mark in a wide field of view.

  The exposure shutter 122 is opened and closed to expose and transfer the pattern on the reticle 101 onto the wafer 105 via the projection optical system 103. The infrared camera 123 is connected to an infrared thermography device (not shown) provided in the control unit 106 (measurement means) that measures the temperature distribution on the surface of the wafer 105. The control unit 106 (control unit) specifies a partial region on the surface of the wafer 105 based on the temperature distribution measured by the control unit 106. Furthermore, regarding this partial area, a plurality of sample shots 408, 409, 410, and 411 are selected, and an array of shots 415 is arranged based on the measured positions of the selected sample shots 408, 409, 410, and 411. calculate.

The control unit 106 (control unit) causes the control unit 106 (measurement unit) to measure the temperature distribution for the other regions after the exposure of all the shots in the partial region, and specifies the partial region and samples shots 408, 409, 410 and 411 are selected and the arrangement of shots 415 is calculated.
Further, the control unit 106 (control unit) has a console 107 (input means) for specifying a partial region and inputting the specific value so that the temperature difference in the partial region is equal to or less than a specific value. The console 107 inputs a lower limit value of the area of the partial area.
The control unit 106 (control unit) estimates the temperature distribution on the surface of the wafer 105 based on the temperature distribution measured by the control unit 106 (measurement unit) and the history of exposure performed on the wafer 105. .
Further, the control unit 106 (control unit) estimates the temperature distribution on the surface of the wafer 105 based further on the material of the wafer 105.
The control unit 106 (control unit) estimates the temperature distribution on the surface of the wafer 105 based on the temperature distribution measured a plurality of times at different times by the control unit 106 (measurement means).
That is, the surface of the wafer 105 is divided into regions by estimating a change in temperature distribution from any one or more of the exposure amount, the exposed region, and the material of the substrate.
Further, the temperature distribution change data during the exposure of the wafer 105 is stored so that the temperature difference in the partial region is equal to or less than a specific value, and the temperature distribution change is determined by the acquired temperature distribution data and the stored temperature distribution change data. The surface of the wafer 105 is divided into regions.
Further, the step of measuring the temperature distribution of the wafer 105 so that the temperature difference in the partial region is not more than a specific value includes the following steps. That is, it includes a step of imaging the surface of the wafer 105 with the infrared camera 123 and a step of calculating the temperature distribution on the wafer 105 using the image data captured by the infrared camera 123.

  FIG. 2 is a plan view of the XYθ stage 104 as viewed from above (Z direction). The XYθ stage 104 of FIG. 1 will be described with reference to FIG. The position of the XYθ stage 104 in the XY direction is controlled by the lengths Lx and Ly measured by the interferometers 117X and 117Y. The position in the θ direction is calculated and controlled as Equation 1 below from the difference between the lengths Ly and Lθ measured by the interferometers 117Y and 117θ and the distance d between the laser beams of the interferometers 117Y and 117θ.

数式１において、θはレチクルセットマーク１１２Ｒ，１１２Ｌを結ぶ線によって決められる装置全体のＸ軸方向とＸＹθステージ１０４のＸ方向が一致する場合に０となるように、予め補正されているものとする。この補正量の求め方は、特許公報第２９８３７８５号に示されている。

In Equation 1, θ is corrected in advance so as to be 0 when the X-axis direction of the entire apparatus determined by a line connecting reticle set marks 112R and 112L and the X-direction of the XYθ stage 104 coincide. . A method for obtaining this correction amount is shown in Japanese Patent No. 2983785.

5 and 6 show the exposure apparatus according to the first embodiment in which a wafer 105 on which a pattern has already been formed is divided into regions according to the temperature distribution of the wafer 105, and a new pattern is superimposed and transferred for each region. It is a flowchart which shows a procedure.
The procedure in the exposure apparatus according to the first embodiment is controlled by the control unit 106, and the sequence will be described below.

  In the first embodiment, an infrared camera 123 connected to an infrared thermography device (not shown) provided in the control unit 106 is used for measuring the temperature distribution. The infrared camera 123 has a measurement temperature resolution of 0.02 ° C. using indium antimony (InSb) and a maximum frame rate of 1 KHz or more. The resolution is further refined by integrating the images. The infrared camera 123 is not installed with an inclination of 50 degrees or more with respect to a line perpendicular to the surface of the wafer 105. Since the temperature of the surface far from the infrared camera 123 is measured low, temperature correction is necessary. The infrared camera 123 is prevented from imaging the entire surface of the wafer 105 by the projection optical system 103. For this reason, the XYθ stage 104 is moved largely to pick up an image, or the movement of the XYθ stage 104 is reduced and picked up a plurality of times. For this reason, it is preferable to install a plurality of infrared cameras 123 to reduce the number of movements and imaging times.

  FIG. 4 shows a state in which a layout 403 that is a collection of shots 415 is superimposed on a state showing the temperature distribution of the wafer 105. The temperature distribution is divided into two regions, a first region 401 and a gray-displayed second region 402. A pattern of a layout 403 is formed on the wafer 105. The pre-alignment sample shots 404 and 405 are sample shots used for pre-alignment. Although the pre-alignment marks 406 and 407 are different from the actual configuration of the first embodiment, they are largely shown at clear positions for easy understanding.

  Sample shots 408, 409, 410, and 411 for alignment are sample shots selected in the second region 402. Alignment marks 412 and 413 are formed on alignment sample shots 408, 409, 410 and 411. Usually, more than two alignment marks are used, but in order to make the explanation easy to understand, in the first embodiment, description will be made with two alignment marks. A part of the layout 403 in the second region 402 can be regarded as the layout 414 for convenience.

  When the sequence is started, as shown in FIG. 5, first, in step S501, the reticle 101 is carried onto the reticle stage 108 and held by suction. In step S502, the reticle 101 is aligned with respect to the projection optical system 103 using the reticle set marks 112R and 112L and the reticle alignment marks 109R and 109L. That is, the imaging device 114 superimposes images of the set of reticle alignment mark 109R and reticle set mark 112R and the set of reticle alignment mark 109L and reticle set mark 112L via mark observation mirrors 113R and 113L, respectively. The reticle unit 108 is moved by the control unit 106 so that the two sets of positional deviations detected from the image output at the time of image capturing are within a predetermined tolerance, and the two sets are aligned.

  When the alignment is completed, a difference between the X-axis direction of the reticle 101 and the X-axis direction of the entire apparatus is obtained from the final result of the positional deviation amounts of the two sets that are within a predetermined allowable value. Is stored as a residual θr. Further, from the same final result, the position of the center of the reticle 101 can be obtained, and the value is stored as a vector R as shown in Equation 2 below. However, the vector R is obtained by multiplying the actual position of the reticle 101 in the first embodiment by the reduction magnification of the projection optical system 103 and further inverting the sign so as to represent the position of the inverted image.

  Next, in step S <b> 503, the wafer 105 is sent onto the wafer stage 118 by a transfer hand mechanism (not shown), and is sucked and fixed onto the wafer stage 118. Next, in step S504, the wafer 105 is pre-aligned with a slightly rough accuracy by using the mark of the pattern already formed on the wafer 105. First, a sample shot for pre-alignment is selected. An example of the selection method may be a method disclosed in JP-A-2001-267214.

  FIG. 4 is a view for explaining alignment marks and sample shots on the wafer 105 in the exposure apparatus of Embodiment 1 of the present invention. Next, as shown in FIG. 4, the pre-alignment marks 406 and 407 formed on the two pre-alignment sample shots 404 and 405 on the wafer 105 are sequentially moved below the off-axis scope 121. Further, the position of each mark is measured from the position of the mark detected from the captured image and the position coordinates of the XYθ stage 104 at that time, and the deviation amount of the entire wafer 105 is measured. As the deviation amount of the wafer 105, the elongation and rotation amount of the wafer 105 are stored in the matrix A and the shift amount of the wafer 105 is stored in the vector S as Equation 3 shown below.

ここで、βｘ，βｙは、ウエハ１０５のＸおよびＹ方向の伸び率を表わし、θｘ，θｙは、ウエハ１０５のＸおよびＹ方向の回転方向のずれ量を表わし、Ｓｘ，ＳｙはＸおよびＹ方向のシフトずれ量を表わす。これらは後のステップで参照する。ここでは、θの値が十分小さいため、ｓｉｎ（θ）≒θ，ｃｏｓ（θ）≒１と表現している。以降の数式でも同様な近似を行なっている。但し、このステップＳ５０４での計測ではウエハ１０５上の２マークの計測しかしないため、ウエハ１０５の回転方向のずれ量は、Ｘ方向とＹ方向を独立に求められない。このため、ウエハ１０５全体の回転誤差θを、下記に示す数式４として記憶する。

Here, βx and βy represent elongation rates in the X and Y directions of the wafer 105, θx and θy represent deviation amounts in the rotational direction of the wafer 105 in the X and Y directions, and Sx and Sy represent X and Y directions. Represents the amount of shift deviation. These will be referred to in later steps. Here, since the value of θ is sufficiently small, it is expressed as sin (θ) ≈θ, cos (θ) ≈1. Similar approximations are performed in the following mathematical expressions. However, since the measurement in step S504 only measures two marks on the wafer 105, the amount of deviation in the rotation direction of the wafer 105 cannot be obtained independently in the X direction and the Y direction. For this reason, the rotation error θ of the entire wafer 105 is stored as Equation 4 shown below.

  In this measurement, the magnification of the off-axis scope 121 is switched to a low magnification, and the mark is detected in a wide field of view. In step S <b> 505, the entire surface of the wafer 105 or an unexposed area of the wafer 105 is imaged by the infrared camera 123. Depending on the position of the wafer 105, it is necessary to move the XYθ stage 104 to a position where the infrared camera 123 can image the entire surface of the wafer 105 or an unexposed area of the wafer 105. Here, the unexposed area indicates an area that has not been exposed yet. Initially, the entire area of the wafer 105 is an unexposed area. It is also possible to reduce the movement of the XYθ stage 104 by taking an image so that there is no portion not photographed by the plurality of infrared cameras 123.

  In step S506, the temperature distribution is calculated by analyzing with the infrared thermography device in the control unit 106 from the image data captured in step S505. In this case, since the temperature of the surface of the wafer 105 far from the infrared camera 123 is measured low, it is necessary to correct the temperature. In step S507, the temperature distribution of the unexposed area of the wafer 105 calculated in step S506 is checked to determine whether the unexposed area of the wafer 105 needs to be further divided. If it is necessary to further divide the area, the process proceeds to step S508. If it is not necessary to divide the area further, the process proceeds to step S509.

  As shown in FIG. 7, it has a console 107 (input means) having an input screen for inputting at least alignment data or exposure data to the control unit 106 (control unit). In order to divide the surface of the wafer 105 into regions, an input screen for parameters required in the first embodiment is shown. This input screen is displayed on the console 107 like other parameter setting screens, and a keyboard and mouse (not shown) are displayed. Enter a value on the touch panel. By a save button (not shown) displayed on the screen, it is saved in a storage device in the control unit 106 together with other parameters. A label 701 is a label indicating that it is a parameter input screen for dividing the surface of the wafer 105 into regions. An item 702 is an item for inputting a maximum temperature difference that can be regarded as the same region, and is input by a temperature (° C.).

  A screen 703 is a screen for inputting the minimum size of the region to be divided, and the proportion of the area of the wafer 105 corresponding to the region is input in proportion (%). That is, a value is input to the parameter input screen, and an area composed of a portion where the adjacent portion is equal to or less than the temperature difference input in the item 702 (all areas formed by dividing the unexposed area) is greater than the ratio input on the screen 703. If it is wider than the wafer 105, the process proceeds to step S508. Further, region division processing is performed. Basically, it is preferable to divide the region by the temperature difference. However, it is desirable to avoid a very narrow area. In some cases, it is preferable to determine the minimum size of the area to be divided for convenience of processing such as alignment. In the first embodiment, the minimum size is determined. Adopt a method to decide.

  In step S508, the unexposed area is divided into a plurality of partial areas based on the temperature distribution data of the unexposed area of the wafer 105 calculated in step S506. In the following description, the unexposed area is divided into a plurality of partial areas in step S508. However, the process in step S508 is not necessarily limited thereto. That is, it may be a process of specifying one partial area in the unexposed area without dividing the unexposed area into a plurality of partial areas. The partial area to be specified may be, for example, similar to the example of the partial area selected in step S509. In step S509, an appropriate area is selected from the unexposed areas of the wafer 105 divided in step S508. For example, an unexposed area adjacent to the exposed area is selected in consideration of the stage moving time. Alternatively, a region having the smallest area of the unexposed region that can reduce the temperature difference in the region is selected. Alternatively, in order to reduce the influence of the exposure energy of other areas, an area away from the area previously exposed in step S512 is selected. If no area division is required in step S507, the unexposed area is one area, and that is the area. First, when this processing is performed, since all the divided areas of the wafer 105 are unexposed areas, an appropriate area suitable for the first case is selected from the unexposed areas.

  Next, in step S510, a sample shot for alignment is selected from the unexposed areas selected in step S509. Here, a group of shots 415 included in the selected unexposed area is regarded as a layout for convenience, and is selected by a normal alignment sample shot selection method. For example, alignment sample shots 408 to 411 are selected from a convenient layout 414 including shots 415 in the second region 402 shown in FIG. 4 that can be regarded as a layout for convenience. The selection is performed by a computer in the control unit 106. An example of the selection method may be a method disclosed in JP-A-2001-267214.

Next, in step S511, alignment is performed using the sample shot selected in step S509.
In step S512, the shot 415 of the area selected in S509 is transferred by exposure. For example, in FIG. 4, the pattern 102 on the reticle 101 is exposed and transferred to a shot 415 of a convenient layout 414 in the second region 402 that can be regarded as a layout for convenience. The processing of step S511 and step S512 will be described in detail later using the flowchart of FIG.

In step S513, it is checked whether an unexposed area still remains. If an unexposed area remains, the process returns to step S505, and the process of the unexposed area described above is repeated from step S505 to step S513. If no unexposed area remains, the process proceeds to step S514.
In step S514, the wafer 105 that has been exposed and transferred is unloaded from the wafer stage 118 by a unillustrated unloading hand mechanism. Further, step S502 to step S515 are repeated until it is determined in step S515 that exposure transfer of all wafers 105 to be processed has been completed.

Next, the alignment of the unexposed area selected in step S511 and the exposure transfer of the unexposed area selected in step S512 will be described with reference to the flowchart of FIG.
First, the flowchart of FIG. 6A showing the alignment processing of the unexposed area selected in step S511 will be described. 6 is also processed by the control unit 106.

  In step S601, the shot arrangement on the wafer 105 and the chip rotation are measured for each sample shot. In each shot pattern formed on the wafer 105, alignment marks 412 and 413 are arranged on the left and right of the shot as shown in FIG. Of the alignment marks 412 and 413, the alignment marks of the shots designated as sample shots in step S510 are sequentially moved under the off-axis scope 121. The position of each alignment mark is measured from the position of the alignment mark detected from the captured image and the position coordinates of the XYθ stage 104 at that time, and the amount of deviation of the entire wafer 105 is measured. Note that the magnification of the off-axis scope 121 at this time is switched to a high magnification to perform more precise measurement. Here, the designated sample shot is, for example, a plurality of shots 408, 409, 410, and 411 shown in FIG. The position of the center of the shot is (Dx, Dy), the position of the alignment mark in the shot is (mx, my), and the position of the alignment mark on the wafer 105 is represented by a vector M in Equation 5 shown below.

また、オフアクシススコープ１２１の位置を下記に示す数式６のベクトルＣで表す。

Further, the position of the off-axis scope 121 is represented by a vector C in Equation 6 below.

オフアクシススコープ１２１の位置を数式６で示されるベクトルＣで表わした場合は、アライメントマークを計測するために、ＸＹθステージ１０４を移動する目標位置は下記に示す数式７で表される。

When the position of the off-axis scope 121 is represented by a vector C represented by Equation 6, the target position for moving the XYθ stage 104 in order to measure the alignment mark is represented by Equation 7 shown below.

このベクトルの位置Ｐに移動した場合、アライメントマークは、オフアクシススコープ１２１で計測可能位置に見える。そこで撮像された画像から検出されたアライメントマークの位置と、その時のＸＹθステージ１０４の位置座標から各マークの位置が得られる。

When moved to the position P of this vector, the alignment mark appears as a measurable position on the off-axis scope 121. Therefore, the position of each mark is obtained from the position of the alignment mark detected from the captured image and the position coordinates of the XYθ stage 104 at that time.

  In step S602, it is checked whether or not the shots measured so far in the selected unexposed area are two or more shots necessary for correction parameter calculation. If two or more shots are measured (in the case of YES), the process proceeds to step S603, and if not (in the case of NO), the process proceeds to step S603.

  In step S603, the values of the deviation amounts βx, βy, θx, θy, Sx, Sy of the entire wafer 105 are newly obtained again using the detected deviation amounts of the respective marks and their measurement positions. In step S603, the matrix A and the vector S obtained in step S504 in the flowchart of FIG. In step S603, in the next measurement, the alignment marks 412 and 413 can be seen almost at the center of the off-axis scope 121.

  Later, in order to investigate the alignment state, the shift amounts βx, βy, θx, θy, Sx, Sy of the entire wafer 105 obtained in step S603 are stored for each divided area. Further, in the second embodiment to be described later, different correction parameters are used for each shot 415 in the exposure transfer process shown in FIG. 6B when exposing a plurality of areas at once. Therefore, the deviation amounts βx, βy, θx, θy, Sx, Sy of the entire wafer 105 obtained in step S603 are stored for each divided area.

  The matrix A and the vector S obtained in step S504 are stored separately, and may be used for calculating the shift amounts βx, βy, θx, θy, Sx, Sy of the entire wafer 105 even in the next selected region. good. However, these correction parameters obtained here only slightly correct the matrix A and the vector S calculated by the pre-alignment in step S504. For this reason, there is no problem even if these correction parameters obtained here are used in place of the matrix A and the vector S calculated in the pre-alignment in step S504. Further, the amount of the i-th chip rotation is obtained from the difference between the measured values of the left and right alignment marks of the i-th sample shot and the distance between the left and right marks as the following Expression 8.

さらに、これまで計測したサンプルショットの平均のチップローテーション量を下記に示す数式９として算出する。

Further, the average chip rotation amount of the sample shots measured so far is calculated as Equation 9 below.

下記の数式１０に示すように、ウエハローテーション部分を取り除き、レチクル１０１の回転残差分θｒを加算して、θｃをチップローテーション量として記憶しておく。

As shown in Equation 10 below, the wafer rotation portion is removed, the residual rotation difference θr of the reticle 101 is added, and θc is stored as a chip rotation amount.

同様に、チップ倍率も下記に示す数式１１として求める。

Similarly, the chip magnification is also obtained as Equation 11 shown below.

さらに、これまで計測したサンプルショットの平均のチップ倍率を下記に示す数式１２で算出する。

Further, the average chip magnification of the sample shots measured so far is calculated by the following formula 12.

下記の数式１３に示すように、ウエハ倍率（β＝（βｘ＋βｙ）／２）部分を取り除き、βｃをチップ倍率として記憶する。

As shown in Equation 13 below, the wafer magnification (β = (βx + βy) / 2) portion is removed, and βc is stored as the chip magnification.

また、マークのチップ内の位置（ｍｘ，ｍｙ）は、設計上の位置（計測基準位置）を（ｍＸ，ｍＹ）とし、チップローテーション、チップ倍率を考慮すると、下記の数式１４で示される。

Further, the position (mx, my) of the mark in the chip is represented by the following formula 14 when the design position (measurement reference position) is (mx, mY) and the chip rotation and the chip magnification are taken into consideration.

チップローテーション、チップ倍率を考慮したアライメントマークのウエハ１０５上の位置は下記の数式１５で示される。

The position of the alignment mark on the wafer 105 in consideration of the chip rotation and the chip magnification is expressed by the following formula 15.

アライメントマークのウエハ上の位置（Ｍｘ，Ｍｙ）は、実際には、ステップＳ６０３では計算式（１）の代わりに計算式（５）を使って算出される。マークを計測するために、ＸＹθステージ１０４を移動する目標位置の計算式（２）にも計算式（５）の結果が使われる。

The position (Mx, My) of the alignment mark on the wafer is actually calculated using the calculation formula (5) instead of the calculation formula (1) in step S603. In order to measure the mark, the result of the calculation formula (5) is also used for the calculation formula (2) of the target position for moving the XYθ stage 104.

  Next, in step S604, it is checked whether or not the measured shot is the last sample shot. If it is not the last (NO), the process is repeated from step S601. If it is the last shot (in the case of YES), the process ends. The deviation amounts βx, βy, θx, θy, Sx, Sy of the entire wafer 105 calculated in step S603, the chip magnification βc, and the chip rotation amount θc are values calculated from the measured values of all the shots of the sample shot. Further, the values calculated from the measurement values of all the sample shots are correction parameters used in steps S605 and S606 in FIG.

  Next, a flowchart showing the exposure transfer process for the selected unexposed area in step S512 shown in FIG. 6B will be described. The processing of this flowchart is also processed by the control unit 106. In step S <b> 605, the XYθ stage 104 is rotated in the θ direction by θw represented by the following equation 16 to align the shot arrangement with the reticle 101.

図３は、本発明の実施例１の露光装置におけるチップローテーション補正を説明する図である。図３（ａ）に示されるように置かれたウエハ１０５は、図３（ｂ）に示されるように回転される。ここで、既にウエハ１０５上に形成されたパターンにチップローテーションがないと仮定できる場合には、レチクル投影像３０１とショット４１５の向きが正確に一致したことになる。あるいは、ＸＹθステージ１０４を、下記の数式１７で示されるθｗだけ回転させ、各ショット４１５の平均の向きをレチクル１０１の向きに合わせても良い。

FIG. 3 is a view for explaining chip rotation correction in the exposure apparatus of Embodiment 1 of the present invention. The wafer 105 placed as shown in FIG. 3 (a) is rotated as shown in FIG. 3 (b). Here, when it can be assumed that there is no chip rotation in the pattern already formed on the wafer 105, the orientation of the reticle projection image 301 and the shot 415 exactly coincide. Alternatively, the XYθ stage 104 may be rotated by θw represented by the following mathematical formula 17 so that the average direction of each shot 415 matches the direction of the reticle 101.

この場合、ウエハ１０５は、図３（ｃ）のように回転され、図３（ｃ）では正確に表せないが、ウエハ１０５上に形成されたパターンにチップローテーションがある場合でも、レチクル投影像３０１とショット４１５の向きが正確に一致したことになる。

In this case, the wafer 105 is rotated as shown in FIG. 3C and cannot be accurately represented in FIG. 3C. However, even if the pattern formed on the wafer 105 has chip rotation, the reticle projection image 301 is displayed. And the direction of the shot 415 exactly match.

  Next, in steps S606, S607, and S608, the circuit pattern on the reticle 101 is exposed and transferred onto the wafer 105. That is, in step S606, the position coordinates Dix and Diy of the i-th shot 415 on the wafer 105 are obtained from the shot arrangement information previously determined by the console 107. Further, the movement target vector Ei of the XYθ stage 104 is obtained from the values of the matrix A and the vector S measured and corrected in steps S603 and S605 by the following equation 18, and the XYθ stage 104 is located at the position obtained by the equation 18. To move.

即ち、ＸＹθステージ１０４は、そのＸＹ方向の位置がウエハ１０５上のショット配列のθ方向（Ｚ軸回り）の回転誤差に基づいて、設計上のショット配列を補正演算した位置となるように移動することになる。

That is, the XYθ stage 104 moves so that the position in the XY direction becomes a position obtained by correcting the shot arrangement on the design based on the rotation error in the θ direction (around the Z axis) of the shot arrangement on the wafer 105. It will be.

In step S607, the exposure shutter 122 is opened and closed, and the pattern on the reticle 101 is exposed and transferred onto the wafer 105 via the projection optical system 103. Of course, any type of exposure light and control method may be used. For example, you may expose with a laser beam, an X-ray, and an electron beam. Further, any exposure method may be used. For example, a batch exposure method or a scanning exposure method may be used. In the determination in step S608, steps S606 to S608 are repeated until it is determined that the exposure of the last shot 415 on the wafer 105 is completed. Here, the process repeated from step S605 indicated by the dotted line 610 shown in FIG. 9 will be described in a second embodiment of the present invention described later.
By repeating steps S606 to S608, the pattern 102 on the reticle 101 is exposed and transferred onto the wafer 105 by using the correction parameter calculated in step S603 of FIG.

  As described above, the following steps are repeated until there is no unexposed area. That is, a step of obtaining a temperature distribution on the wafer 105, a step of dividing an unexposed region with an appropriate temperature difference, a step of selecting one region from the regions, and alignment with the selected region Measuring and calculating a position correction parameter. Further, the process of correcting the exposure position using the position correction parameter for the area where the position correction parameter is calculated and exposing and transferring the reticle pattern to the wafer 105 is repeated until there is no unexposed area. By repeating until there is no unexposed area, the alignment of the wafer 105 can cope with the non-linear component generated by the exposure apparatus in the alignment of the wafer 105, and the alignment accuracy is increased. I can do it. Further, it is possible to cope with a change in the temperature of the wafer 105 during exposure.

  According to the exposure apparatus of the first embodiment described above, the wafer 105 is nonlinearly deformed by heat among the nonlinear components created by the exposure apparatus when the wafer 105 is aligned by having the following steps. It is possible to deal with the components and increase the alignment accuracy. That is, the method includes a step of obtaining a temperature distribution of the wafer 105 and a step of dividing the surface of the wafer 105 by the temperature distribution. Further, the method includes a step of calculating alignment correction parameters for each region and calculating a position correction parameter, and a step of correcting an exposure position using the position correction parameter for each region and exposing and transferring a reticle pattern to the wafer 105.

  Next, an exposure apparatus according to Embodiment 2 of the present invention will be described. In the first embodiment, the region is divided by the temperature distribution, one region of the divided regions is aligned and exposed, and another region is processed again from the region division by the temperature distribution. In the first embodiment, the temperature on the wafer 105 is changed even during the processing of the wafer 105. However, the temperature change on the wafer 105 during processing may be small relative to the required alignment accuracy. For this reason, there is a case where it is desired to improve the throughput rather than the case where the temperature on the wafer 105 being processed corresponds to the change, and this embodiment corresponds to this. The exposure apparatus according to the second embodiment divides the area according to the initial temperature distribution, performs area unit alignment on all the divided areas, and then performs position correction on all shots on the wafer 105. Exposure. The control unit 106 (control unit) divides the surface of the wafer 105 into a plurality of partial regions based on the temperature distribution measured by the control unit 106 (measurement means). Further, for each of the divided partial areas, sample shot selection and shot arrangement calculation are performed.

A processing procedure in the exposure apparatus according to the second embodiment will be described with reference to the flowchart in FIG. In the second embodiment, the wafer 105 on which a pattern has already been formed is divided into regions according to the temperature distribution of the wafer 105, the region unit is aligned with respect to the entire region, and position correction is performed on all shots on the wafer 105. A new pattern is transferred while being transferred. This process is processed by the control unit 106.
Since the configuration of the exposure apparatus of the second embodiment is mostly the same as that of the exposure apparatus of the first embodiment, the process displayed in gray in the flowchart of FIG. 8 is the same as the process of the flowchart of FIG. Is omitted. That is, steps S501 to S508 are the same as steps S801 to S808, steps S510 and S511 are the same as steps S810 and S811, and steps S514 and S515 are the same as steps S814 and S815.

Here, the processing of steps S809, S812, and S813 will be described.
In step S809, an appropriate area is selected from the unexposed areas on the surface of the wafer 105 divided in step S808. For example, in consideration of the stage moving time, an unexposed area adjacent to the exposed area is selected. If it is not necessary to divide the area in step S807, the unexposed area is one area, which means that area. In addition, when this processing is performed for the first time, since all the divided areas of the wafer 105 are unexposed areas, an appropriate area suitable for the first case is selected from the areas.

  In step S812, it is checked whether there is an unaligned area yet. If there is an unaligned area yet, the process proceeds to step S809, and the process is repeated from the area where the area is selected from the remaining areas. If there is no unaligned area yet, the process proceeds to step S813.

  In step S813, the pattern 102 on the reticle 101 is exposed and transferred to the shot 415 in the layout 403 on the wafer 105, and the processing in the second embodiment is performed as shown in the flowchart of FIG. Are continuously exposed. The difference between the first embodiment and the second embodiment is that the process that is repeated at the time of exposure is not repeated from step S606, but is repeated from step S605 indicated by the dotted line 610. That is, since the rotation errors θx and θy of the entire wafer 105 calculated for each region are different, even if exposure is performed in units of divided regions or exposure is performed in the order of Row and Column regardless of the region, each time the region changes, step S605 is performed. This is because θ correction driving of the XYθ stage 104 is required. For this reason, this step S605 may always be executed as shown in the flowchart of FIG. 6, or may be executed only when necessary because there is a determination (not shown) and the area changes. In addition, the temperature of the wafer 105 is monitored using the infrared camera 123 during exposure, and when the temperature difference appears in the unexposed area beyond a certain level, the processing of the wafer 105 is switched to the method of the first embodiment. You can also.

  According to the second embodiment described above, by including the following steps, the alignment of the wafer 105 can cope with a nonlinear component in which the wafer 105 is deformed by heat among the nonlinear components produced by the exposure apparatus. Can improve the throughput and increase the alignment accuracy. That is, the method includes a step of obtaining a temperature distribution with respect to the wafer 105 and a step of dividing an unexposed region by an appropriate temperature difference. Further, the step of calculating the position correction parameter by performing alignment measurement for each of the plurality of regions continuously, and correcting the exposure position using the position correction parameter for the plurality of regions, and the reticle pattern on the wafer 105. And exposing and transferring to the substrate.

Next, an exposure apparatus according to Embodiment 3 of the present invention will be described. In the first and second embodiments described above, the region is divided according to the acquired temperature distribution of the wafer 105. However, it is also possible to determine the division of the region by predicting the change in temperature distribution due to the thermal energy of shot exposure and the change in temperature distribution due to the passage of time caused by the thermal energy diffusion. It is necessary to consider the material of 105.
In the third embodiment, in the temperature distribution calculation in step S506 in FIG. 5 and step S806 in FIG. 8, the imaging data captured in steps S505 and S805 is analyzed by the infrared thermography apparatus in the control unit 106, and the wafer 105 Calculate the temperature distribution across the entire surface. In this case, since the temperature of the surface of the wafer 105 far from the infrared camera 123 is measured low, the temperature is corrected. However, in consideration of the exposure amount, exposure area, and material of the wafer 105 at that time, a change in temperature distribution due to thermal energy of shot exposure and a change in temperature distribution due to the passage of time caused by thermal energy diffusion are expected. The temperature distribution is corrected so that the region can be properly divided.

  According to the third embodiment described above, the region is divided by predicting the change in temperature distribution from the exposure amount, the exposure area, the material of the wafer 105, and the like. With this area division, in the alignment of the wafer 105, it is possible to deal with a nonlinear component in which the wafer 105 is deformed by heat among the nonlinear components generated by the exposure apparatus, and the alignment accuracy can be increased. Furthermore, it is possible to cope with a change in the temperature of the wafer 105 due to exposure.

Next, an exposure apparatus according to Embodiment 4 of the present invention will be described. In the first and second embodiments described above, the region is divided according to the acquired temperature distribution of the wafer 105. However, in the fourth embodiment, it is possible to determine the division of the region by predicting the change in the temperature distribution of the wafer 105 acquired using the change data of the temperature distribution of the wafer 105 stored during the previous exposure. In the fourth embodiment, in step S512 of FIG. 5 and step 813 of FIG. 8, the temperature distribution is calculated by analyzing the image data captured by the infrared camera 123 using the infrared thermography apparatus in the control unit 106. Further, change data of the temperature distribution during exposure is recorded in a storage device in the control unit 106.
In the temperature distribution calculation in step S506 and step S806, the temperature distribution is calculated by analyzing with the infrared thermography apparatus in the control unit 106 from the image data captured in step S505 and step S805. In this case, the temperature of the wafer 105 surface far from the infrared camera 123 is measured low. For this reason, the temperature is corrected, but the temperature distribution so that the region can be appropriately divided so as to be suitable at the time of alignment and exposure in consideration of the change data of the temperature distribution during exposure recorded at step S512 and step 813 at that time. Make corrections.

  According to the fourth embodiment described above, the temperature distribution change data is predicted by the step of storing the temperature distribution change data during exposure, the acquired temperature distribution data, and the stored temperature distribution change data. And dividing the surface of the wafer 105 into regions. For this reason, in the alignment of the wafer 105, it is possible to deal with a nonlinear component in which the wafer 105 is deformed by heat among the nonlinear components generated by the exposure apparatus, and the alignment accuracy can be increased. Furthermore, it is possible to cope with a change in the temperature of the wafer 105 due to exposure.

(Example of device manufacturing method)
A device (semiconductor integrated circuit element, liquid crystal display element, etc.) is a step of exposing a substrate (wafer, glass plate, etc.) coated with a photosensitive agent using the exposure apparatus of any of the embodiments described above, and its exposure. And a step of developing the formed substrate. Processes for processing the developed substrate include etching, resist stripping, dicing, bonding, packaging, and the like.

1 is a perspective view of a semiconductor exposure apparatus according to Embodiment 1 of the present invention. It is the top view which looked at the XY (theta) stage which comprises the semiconductor exposure apparatus of FIG. 1 from the upper direction (Z direction). It is a figure explaining the chip | tip rotation correction | amendment in the exposure apparatus of Example 1 of this invention. It is the figure which overlapped the layout which is a collection of shots on the figure which shows the temperature distribution of the wafer in Example 1 of this invention. It is a flowchart which shows the process sequence of the exposure apparatus which concerns on Example 1 of this invention. It is a flowchart of the step regarding alignment and exposure of the exposure apparatus which concerns on Example 1 of this invention. It is an input screen of the parameter required in order to divide the wafer surface in Example 1 of the present invention. It is a flowchart which shows the process sequence of the exposure apparatus which concerns on Example 2 of this invention. It is a flowchart of the step regarding alignment and exposure of the exposure apparatus which concerns on Example 2 of this invention.

105: Wafer, 106: Control unit, 107: Console, 108: Reticle stage, 118: Wafer stage, 121: Off-axis scope, 404, 405: Pre-alignment sample shot, 406, 407: Pre-alignment mark, 408- 411: Sample shot for alignment selected in second region 402, 412 and 413: alignment mark

Claims (10)

An exposure apparatus that measures positions of a plurality of sample shots on a substrate, calculates an array of shots based on the measured positions, positions each shot according to the calculated array, and exposes the shots,
Measuring means for measuring the temperature distribution of the surface of the substrate;
Based on the temperature distribution measured by the measuring means, the partial region of the surface is specified, a plurality of sample shots are selected with respect to the partial region, and based on the measured positions of the selected plurality of sample shots A control unit for calculating the arrangement of shots;
An exposure apparatus comprising:   After the exposure of all the shots of the partial area is completed, the control unit causes the measurement unit to measure the temperature distribution with respect to the other areas, specifies the partial area, selects the sample shot, and calculates the shot arrangement. The exposure apparatus according to claim 1, wherein:   The control unit divides the surface into a plurality of partial regions based on the temperature distribution measured by the measuring unit, and selects a sample shot and sets the shot arrangement for each of the divided partial regions. The exposure apparatus according to claim 1, wherein calculation is performed.   The exposure apparatus according to claim 1, wherein the control unit specifies the partial region so that a temperature difference between the partial regions is equal to or less than a specific value.   The exposure apparatus according to claim 4, further comprising an input unit that inputs the specific value.   The exposure apparatus according to claim 1, further comprising an input unit that inputs a lower limit value of the area of the partial region.   The control unit estimates the temperature distribution of the surface of the substrate based on the temperature distribution measured by the measuring unit and the history of exposure performed on the substrate. The exposure apparatus according to any one of 1 to 6.   The exposure apparatus according to claim 7, wherein the controller estimates a temperature distribution on the surface of the substrate further based on a material of the substrate.   The said control part estimates the temperature distribution of the surface of the said board | substrate based on the said temperature distribution measured in multiple times at the different time by the said measurement means, The Claim 1 thru | or 6 characterized by the above-mentioned. Exposure device. A step of exposing the substrate using the exposure apparatus according to claim 1;
Developing the substrate exposed in the step;
A device manufacturing method comprising:

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