JPH0396219A - Aligning method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an alignment technique, in particular, to measuring the positions of marks formed at multiple locations on an alignment target,
Regarding alignment technology that performs alignment work based on this measurement data, it is applied, for example, to reduction projection exposure equipment that exposes circuit patterns on a wafer in a step-and-repeat manner in the manufacturing process of semiconductor devices. This article concerns techniques that are effective when used in alignment techniques. [Prior Art] As an alignment method used in a step-and-repeat reduction projection exposure apparatus, for example, Japanese Patent Laid-Open No. 61
-Described in Publication No. 44429? There is a way to In other words, this alignment method sequentially aligns each of a plurality of chip patterns regularly arranged on the substrate to be processed along set array coordinates with respect to a predetermined reference position using a step-and-repeat method. The method includes the following steps: Prior to the step-and-repeat alignment, some of the plurality of chip patterns are aligned with the reference position by moving the substrate to be processed based on the designed arrangement coordinate values of the chip patterns; The process of actually measuring each ■ position. When it is assumed that the designed array coordinate values and the actual array coordinate values to be aligned by the step-and-repeat method have a unique relationship including a predetermined error parameter, the plurality of actual measured values and determining the error parameter so that an average deviation between the actual array coordinate value and the actual array coordinate value is minimized. The actual array coordinate values are calculated based on the determined error parameter and the designed array coordinate values, and during step-and-repeat alignment, the calculated actual array coordinates all{! a step of positioning the substrate to be processed according to the processing target; [INI to be solved by the invention] In such a positioning method, an X, yt set or two sets of reference marks are inserted into each exposure shaft of the step-and-repeat method, and these marks are is used to measure the position error and deformation of the wafer, perform alignment with respect to the reference mark for each shot, and perform exposure. At this time, if the amount of deformation of the wafer is loppm, a deviation of approximately 0.15 μm will remain in the 15 mm span within the shoot. However, in conventional alignment methods, this error is not corrected. The reason why this error has not been corrected in the past is as follows. (1) Since the size of Sig7 is small at 15mm,
Wafer deformation can be ignored. (2) In order to correct errors in the syllot, it is necessary to perform position measurements at multiple points within the syllot, but this not only reduces throughput, but also increases the size of the device due to multiple optical systems and increases the This will lead to increased costs. However, with the current trend toward higher integration and thinning, the margin for alignment has become smaller, and the influence of errors caused by wafer deformation has become relatively large, making it impossible to ignore errors within the sitat. It has become. An object of the present invention is to provide an alignment method that can easily measure and correct intra-slot errors. The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings. [Means for Solving the Problems] Representative inventions disclosed in this application will be summarized as follows. That is, it is an alignment method applied to an exposure method in which a wafer on which circuit patterns and alignment marks have already been formed is sequentially overlaid and exposed with a next layer pattern by a step-and-repeat method for each job, Each of the alignment marks formed at a plurality of locations on the wafer is sequentially aligned in a step-and-repeat manner to each of the reference positions corresponding to the marks determined by the design of the pattern to be exposed, A positioning method for accurately performing exposure for each shipment for each positioning, characterized by comprising the following steps. The alignment mark formed on the wafer by actually sequentially moving the wafer based on the designed Go reference position prior to the step-and-repeat alignment involving exposure for each job. A process in which position measurements are performed for some of the groups. A step in which each composite error (ΔX, ΔY) at the position of each mark is determined from the difference between the measured value for each mark and the value at the reference position corresponding to each mark. Through statistical calculation processing using these compound errors (ΔX, ΔY), off {! ｝fl
Difference (X-tt, Y-tt), Elongation error (P.P
, ), and a process in which rotational errors (θx, θy) are determined, respectively. A step in which the determined expansion/contraction error (P., PW) is used to determine the magnification error (S.) within the shot. A step in which the determined rotation error (θx, θy) is used to determine the rotation error (Sσ) within the ship. A step in which each error determined in this manner is corrected during actual positioning using the step-and-repeat method involving exposure for each shot. [Operation] Positional misalignment errors within the chict are caused by deformation and misalignment of the entire wafer as the object to be aligned. Therefore, according to the above-mentioned means, the deformation and positional deviation of the entire wafer as an alignment target is determined by position measurement at multiple points on the wafer as an alignment target, and from the results, the amount of deformation within the shoot is further determined. , the positional deviation is found. Then, by correcting the amount of deformation and positional deviation within the shaft and aligning, most of the errors within the shaft are corrected and the position is aligned without having to measure the position of multiple points within the shaft. ．． [Embodiment] Fig. 1 is a flowchart showing a positioning method commonly used in a reduction projection exposure apparatus which is an embodiment of the present invention, Fig. 2 is a perspective view showing the reduction projection exposure apparatus, and Fig. 3 is a flow diagram showing a wafer A schematic plan view of a wafer showing the coordinate system of the cut point in alignment. Figure 4 is a schematic diagram showing the offset of the cut point, which is one of the causes of wafer error. A schematic diagram showing the expansion/contraction error, Figure 6 is a schematic diagram showing the rotation of the X-axis of the chaiyot, Figure 7 is a schematic diagram showing the rotation of Y Yuzu in the chiyot, and Figure 8 also shows the rotation error of the chiyot. The schematic diagram, Fig. 9 is a schematic diagram showing the magnification error of Schott, and Fig. 1O is a schematic diagram showing the orthogonality error of Schott, and Figs. 11, 12, and 13 explain the effect. These are schematic diagrams for each method. In this embodiment, the present invention is applied to an I! ! Step-and-repeat reduction projection exposure system in the process
I will clarify an example of how to align the position in a stepper (stepper). Before explaining the alignment method of the present invention, a reduction projection exposure apparatus will be briefly explained. Second
The figure is a perspective view showing an overview of the reduction projection exposure system. In the figure, an original image of a semiconductor device pattern is drawn on a reticle 6, and a copy of this is projected onto a wafer 1 through a reduction projection lens 7. This lens 7 is designed to have a telecentric link system on the wafer side. The wafer l is automatically transferred from the cassette 8 onto the loading table 9,
After rough positioning is performed by the pre-alignment device 1O, the transfer arm 11 vacuum-chucks the chuck 13 on the XY stage 12. On the other hand, the reticle 6 is
The reticle alignment optical system 20 performs positioning so that its center coincides with the center of the reduction projection lens 7. In the case of the reduction projection exposure apparatus according to this embodiment, a through-the-lens position detection X system 2l and a position detection Y system 22 are provided for positioning the reticle 6 and the wafer l. This detection system irradiates the alignment mark formed on the wafer l with light of a wavelength to which the resist is not sensitive, and scans a slit to detect the specular reflection position from the mark using a photomultiplier tube. It is configured to detect 6 window patterns. Further, the wafer l is arranged to have its position measured by a laser interferometer length measuring needle 30. Then, from these measurement data, the deviation of the wafer pattern from the design grid position is determined. A laser beam 31 emitted from a laser beam length meter 30 is separated by a spectrometer 32. One laser beam 3l is transmitted to an X-axis mirror 33 attached to the XY stage l2.
is irradiated. This irradiation light is reflected by the X-axis ξ mirror 33 and returns to the laser beam length measuring meter 30, and the Xi! of the xY stage 12! am is detected. Further, the other laser beam 31 is transmitted to the XY stage l2 via mirrors 34 and 35, respectively.
The beam is irradiated onto the Y-wheel poison roller 36 attached to the. The laser beam 31 irradiated and reflected by this Y-wheel mirror 36 passes through the mirrors 34, 35 and the spectroscope 32, and reaches the laser interferometer 30, where it reaches the Y-wheel of the XY stage l2.
! Spells are now detected. The xY stage 12 is controlled to move in the X-axis direction with high precision by an X-axis motor 37, and is also controlled to move 11 m with high precision in the Y-axis direction by a Y-axis motor 38. ．． On the other hand, the wafer l on the chuck 13 whose work has been completed is transferred to the unloading table 4 by the transfer arm tt.
Transferred onto 0. This unloading table 40
The wafers transferred thereto are sequentially accommodated in a collection cassette 41 by an air bearing mechanism provided on the unloading table 40, for example. Next, a case will be described in which a positioning method, which is an embodiment of the present invention, is applied to this exposure apparatus. Note that this alignment method is performed for the second and subsequent layers of the wafer 1 as the alignment target, and the circuit pattern and alignment marks have already been formed on the wafer 8. ．． The wafer l, on which patterns and alignment marks have already been formed, is subjected to rough alignment in the XY directions and the rotational direction by having alignment marks placed at two points on the wafer l by a real alignment device. Ru.゛Clearly, in the case of this exposure device, XY
Since there is no rotation mechanism on the stage l2, it is positioned on the pre-alignment device 10 so that the rotational error is minimized. The wafer 1 transferred and attracted onto the chuck 13 is further subjected to global alignment using the two shots 2 inside the wafer 1. In shot 2, all X marks A and Y marks A are arranged. For example, as shown in FIG.
A shot 2 inside is placed under the reduction projection lens 7,
It is moved and positioned by stage l2. Along with this movement, the error position with respect to the design value (design shot) in the Y direction is determined based on the data of the position detection Y system 22, and the error position in the X direction is determined based on the data of the tag position detection X system 2. A similar amount of error is required. Next, in the same way, the XY position is moved for shot 2 called B in wafer l, and the error with respect to the design (j! (designed shot)) is determined. From the above results, the The rotation, the offset in the XY directions (off), and the expansion and contraction of the wafer 1 in the Wafer 1 is moved in a step-and-repeat manner and positioned appropriately, and the reticle position is transferred to wafer 1 each time.Nowadays, where even higher precision is required, after global alignment, , the detection of the X mark A. and the Y mark A is performed for each shot.The XY stage 12
is precisely controlled, or, as shown in FIG. 2, residual error correction in x and Y is performed by a reticle fine movement system 42 that supports the reticle 6, and then Silat exposure is performed. In the case of such "in-situ exposure method" chip alignment, as shown in FIGS. 11(a), 12(a), and 13(a), the elongation error of the wafer etc., the error between shots is corrected and
LrJA (b), Figure 12 (b) and Figure 13 (1)
) will be performed, respectively. However, as shown in Figures 11 (0)) and 12 (in Figures BL and 13), errors within the shot remain. Therefore, in order to perform highly accurate alignment as shown in FIGS. 11(C), 12(C), and 13(C), it is necessary to correct this error. As a means of performing this highly accurate positioning, two points within the same slit, for example, in FIG. 11(a), (
A. , , A, 1) and ( A −* , A yz
) There is a method for performing position measurement using alignment marks and correcting errors in the scint based on this measurement data. However, in this case, multiple position detection systems are required, so
The equipment cost is high, and since it measures two points at the same time, it is impossible to remove false detections from linearity.
Correction within the system is performed with the false detection still included. As a result, the reliability of positioning decreases, and when multiple measurements within a shot are performed using one detection system, the throughput decreases due to the increase in the number of measurement points within the shot. In view of these circumstances, the alignment method according to this embodiment uses the symbol
Instead of aligning multiple points within the wafer, errors within the wafer are corrected based on the measurement results of the wafer's positional deviation and deformation. That is, based on the data obtained by position measurement at two points within the wafer, the wafer expansion/contraction MPy# and the wafer rotation amount θy are:
It is determined by the following formula. Py-(ΔYl-ΔY.)/D...(1)
I y − (A X I−ΔXi/D −
(2) Simply put, this result is the amount of expansion/contraction correction in Chironto,
This is used as a rotation correction amount for the shoot, and the correction can be executed by a magnification correction mechanism and a reticle rotation a mechanism, which will be described later. Furthermore, the following methods are available for highly accurate correction. In this embodiment, the positions of a plurality of marks placed on a wafer as an alignment target based on design data are measured by chimp alignment. The composite errors ΔX and ΔY, which are expressed as the difference between the measured results and the design data, are expressed by the error factors shown in Figure 2 below. ΔX ”X *g t + P *+θ, +Sa +
S? l +S@+3,1ε・
...(3》ΔY turtle Y*tt+Pw+θ,+Sθ+S+*
+S*+S. +ε． (
4) Here, X sf t % Y me t is the fourth
As shown in the figure, this is the offset of the shot 2 with respect to the designed shot 43 in the XY axis directions. P. , P
7 is shot 4 by design, as shown in FIG.
This is the expansion/contraction error of Shit 2 in the XY axis direction with respect to 3. θx, θy are XY of the position ν2 with respect to the designed position 43, as shown in FIGS. 6 and 7.
The rotational error in the axial direction, Ss, is the rotational error of the shaft 2 relative to the shaft 43 due to design, as shown in FIG. Shi against! This is the magnification error of cut 2. Also,
Sa is a nonlinear distortion error within a shot, and ε is a nonlinear position error occurring during step-and-repeat. Furthermore, So is the orthogonality error of the sitat with respect to the sitat 43 due to design, as shown in Figure 1O. Among these error factors, other components except for the nonlinear distortion error S in the position and the nonlinear position error ε are based on the results previously measured in chip alignment as linear errors of the wafer. It can be calculated using statistical methods. Using this method, each error factor, excluding the above-mentioned Ss and ε, is expressed as a linear equation by averaging processing and regression calculation from the coordinate data obtained by chimp alignment within the wafer.
Below, we will explain the formulas for calculating each error in sequence. In the case of this embodiment, only the detection of the X mark and Y mark in sheet I7 is executed. As shown in Figure 3,
The position measurement error for any hit is ΔXi-i, ΔYj
．． It is represented by j. ? Fuset X. (2) Ymtz is calculated by the following formula, which calculates the average of all measured data. j-1 izenl Here, Nj, N, is the number of measurement data of each matrix. Here, N is the number of measurement data, M. %M, is the matrix. At this time, each chapter's expansion and contraction P. , P, and rotation θ of each axis
x and θy are calculated before offset calculation. That is,
After the expansion/contraction and axis rotation of the wafer are calculated, the offset is calculated. Expansion and contraction of each chapter P. , P, and rotation of each axis θyo, θ,
is obtained by regression calculation using K L s averaged for each column and vj averaged for each row in the following equation. Here, S. , S, is the exposure pitch. j-1 i=1 From the above results, the coordinates of the center of the shot to be exposed on the wafer, X t* % Y tx, with the wafer center as the origin, are expressed as follows. Xzw-Xatt +p x-L x 10θy-Ly
-0!9Ytm-Y-tt +p y H L y+θ
(X-L x -Ofi) Here, Lx, Ly indicate the distance of each shot center from the wafer center by X, Y@. Also, the magnification error SN and rotation error Sθ within a shot are expressed by the following equations. S N = (Px + Py) / 2
−07) So = (θχ+θy)/2
・=Q Next, the magnification error within the shot S.
4, and a specific method for correcting the rotation error Sθ in the shot. First, the shayot magnification error S. We will explain the correction method for . In the reduction projection exposure apparatus according to this embodiment, the reduction projection lens 7 is configured so that the wafer side is telecentric, so that even when the wafer 1 is moved in the optical axis direction of the lens 7, However, the magnification of the shot hardly changes. On the other hand, since the reticle side is not configured to form a telecentric link, when the reticle 6 is moved in the optical axis direction, the magnification changes. Therefore, this principle is utilized to correct the siggon magnification error S1. That is, by moving the reticle 6 up and down by the fine movement mechanism 42, the magnification error is corrected. However, the magnification error correction method is not limited to this method. For example, in the case of an optical system in which the reticle side is also telecentric, correction can be made by moving part of the reduction lens. The magnification error S can also be corrected by pressure inside the lens or by filling a gas with a different refractive index in the middle of the L optical system. Next, a method of correcting the rotational error Sθ in the shot will be explained. This rotational error Sθ is caused by the rotational movement mechanism 42 of the reticle,
This can be corrected using the reticle alignment optical system 20. In other words, the shot rotation angle is directly corrected as the reticle rotation angle. Note that if the reticle is not rotated, that is, if the reticle rotation fine movement mechanism 42 is not installed, the correction can be made using a wafer rotation movement mechanism. By the above calculation, the offset error CX. tt, Y-tr), expansion/contraction error (Px,
Py), rotation error (θX, θy), as well as intra-shot magnification error (S.) and rotation error (SQ), the actual positioning is performed using a step-and-repeat method with exposure for each shot. It will be executed. At this time, the error determined as described above is caused by the X-axis motor 37, Y-axis motor 38, reticle fine movement *t*,
It is automatically corrected by operating the rotary fine motor horizontally, etc. Here, the magnification error CSM ) and the rotation error (
Since S#) is determined as a single value for one wafer, correction for each shot is substantially performed at the same time as the initial alignment. According to the above embodiment, the following effects can be obtained. (1) The amount of wafer deformation is approximately 10 ppm depending on the process.
A linear error of approximately 0.15 μm/15 mm may occur within the seat. The positioning method according to this embodiment corrects most of these errors, making it possible to perform highly accurate positioning. (2) Furthermore, by not performing measurements within the sitat, it is possible to prevent a decrease in throughput, and there is no need to perform correction operations for each sitat.
This makes it possible to further prevent throughput from decreasing. (Normally, errors in reticle manufacturing include in-line errors, and there may also be changes in magnification during transfer due to the M thermal effect of the optical system due to wafer exposure. Positional deviations other than wafer deformation may occur) Since positioning can be performed to minimize errors, it is possible to achieve even higher accuracy. It is necessary to perform positioning within the shot.At this time, in order to prevent a decrease in throughput, false detections can be eliminated by using a small number of measurement points, achieving highly accurate positioning. Although the invention made by the present inventor has been specifically explained above based on examples, the present invention is not limited to the above-mentioned examples, and can be modified in various ways without departing from the gist thereof. Needless to say, in the above embodiment, as shown in the equation 0, aS, the force t piece Ilkx which takes the average of the deformation amounts of X and Y
Alternatively, by using only the measurement result of Y, the magnification error S. and rotation error Sθ can be corrected. In addition, by averaging processing and linear regression calculation, the position of Uehachi,
Although the deformation is calculated, the L deformation of the wafer can be calculated using other statistical processing calculations such as the method of least squares, and is not limited to the above calculation formula. Furthermore, the orthogonality error within the shoot caused by the wafer orthogonality deformation error (see FIG. 13(a)) included in the nonlinear error within the shoot is calculated by S. Then, this orthogonality error S. is expressed by the following equation. S. One (θ.-θV)
...09 At the same time, S. 1θyo, or θ,
By setting (to), it is possible to separate the rotation error component of the (to) equation and the orthogonality deformation component of the OI equation, so that highly accurate positioning can be performed. Among these, the correction for the rotational error component can be performed by the previously described correction method for the rotational error Sa. In addition, in the case of a projection optical system that uses a lens, the correction for the orthogonal deformation can be performed using the same principle as the correction for the magnification error S4 due to the movement of the reticle in the optical axis direction described above. can. In other words, correction can be performed by slightly moving the diagonal position in the optical axis direction with respect to the center of the reticle by using the upper and lower movement mechanisms independent of the four corners of the reticle, thereby elastically deforming the reticle.
At this time, residual errors occur in the magnification and rotation direction. In the embodiment described above, the XY table holding the wafer is used as a reference, and errors in scale, rotation, etc. are corrected with respect to this reference. In addition to adjusting linear errors such as scale and orthogonality in order to use the x-Y stage as an absolute reference, it is important to minimize nonlinear errors including yawing and pitching in advance. In addition, prior to wafer measurement, the pattern position error (R)1, Rθ, R●) regarding the reticle during reticle manufacturing.
, and the transfer position error (L., Le
%t,o), and set S,1', Sθ', So' so that the alignment error between the pattern transferred onto the wafer and the reference pattern on the wafer is minimized.
By correcting this, it is possible to achieve even higher accuracy. SM ″ = SM + Rn + Ln
...(2l)Sθ'=Sθ+Rθ+L. e
...(22) So' = S6 + R
o + Lo...(23) Furthermore, 1
The method of measuring the position of multiple points for each shot and correcting the shot position and shot position errors takes time, but it can prevent false detections and can be expected to improve accuracy. Therefore, the previous correction Is. ',Sθ',S
．． ′ by adding a constant value, TS)1′, “rsθ′,
Let Tso' be Tso'. TSM ' = S + <' ±TI4 ・
・・(24)TSθ′=Sθ′±Tθ・
...(25) TSO' = SQ' ±T0
...(26) This TSM', TSθ', TS
．． ' was determined by in-situ measurement based on S. ，
Sθ,S. If is within this range, the intra-shot measurement results are used to perform alignment. On the other hand, if it exceeds this range, it is assumed that a false detection has occurred, and SN', S
θ', 30' is used to perform intra-synthetic correction. In the above embodiments, it has been described that the intra-shot errors are corrected in all cases, but if the wafer deformation and positional errors are minute and the intra-shot correction accuracy is less than or equal to the intra-shot correction accuracy,
Alternatively, for products and processes that do not require correction, it is effective to perform correction selectively. In the above description, the invention made by the present inventor is mainly applied to the exposure technology in semiconductor device manufacturing, which is the background field of application of the invention, but the invention is not limited thereto.

For example, the step-and-repeat XL? It can be applied to measurement techniques that measure the electrical characteristics of each chip using a step-and-repeat method, such as a stepper or a projection-type stencil with equal magnification. The present invention can be applied to at least a technique in which step-and-repeat is repeated for an alignment target and work is performed for each unit area of the alignment target. [Effects of the Invention] The effects obtained by typical inventions disclosed in this application are as follows. In a step-and-repeat exposure method for wafers, prior to actual alignment, position measurement is performed for some of the alignment marks, and statistical processing based on this measurement data is used to calculate errors and siggots for the entire wafer. By determining internal errors and correcting these errors during actual positioning, it is no longer necessary to measure the position within the shot, allowing for highly accurate positioning even within the shot without reducing throughput. can be realized.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing a positioning method commonly used in a reduction projection exposure apparatus that is an embodiment of the present invention. FIG. 2 is a perspective view of the reduction projection exposure apparatus, and FIG. A schematic plan view of a wafer showing the system, Fig. 4 is a schematic diagram showing shot offset, which is one of the causes of wafer error, Fig. 5 is a schematic diagram showing the shot expansion/contraction error, and 6rA is the same. Figure 7 is a schematic diagram showing the rotation of the shot on the X axis, Figure 7 is a schematic diagram showing the rotation of the shot on the Y axis, Figure 8 is a schematic diagram showing the rotation error of the shot, and Figure 9 is a schematic diagram showing the rotation error of the shot. FIG. 10 is a schematic diagram showing the magnification error. FIG. 10 is a diagram also showing the orthogonality error of the scissor. FIGS. Wafer, 2...shot, 3...chip,
4... Positioning mark, 5... Incomplete shot,
6... Reticle, 7... Reduction projection lens, 8...
Cassette, 9...Loading table, 1 0-...
・Bria alignment device, 1l...transfer arm, 12
-XY stage, ta-... chuck, 20-... reticle alignment optical system, 21... position detection X system,
22...Position detection YF. 3 0-... Laser interferometer length meter, 3l... Laser light, 32... Spectrometer, 33...
・X-axis roller, 34, 35...Mirror, 3 6-Y
Axis rolling roller, 3 7-X-axis motor, 3B/-y-axis motor, 40... Unloading table, 41...
・Collection cassette, 42... Reticle fine movement system, 43.
...by design.

Claims (1)

[Claims] 1. Each of the alignment marks formed at a plurality of locations on the alignment target is sequentially aligned to each of preset reference positions with respect to these by a step-and-repeat method. In the above alignment method, prior to the step-and-repeat alignment, position measurements are performed for some of the alignment marks, and the overall error is determined by calculations based on this measurement data, and further, Based on this overall error and the measurement data, the error within the small area at each time when the positioning is performed sequentially using the step-and-repeat method is determined, and then, with this small area error and the overall error corrected, A positioning method characterized by sequentially performing positioning using a step-and-repeat method. 2. An alignment method applied to an exposure method in which a wafer on which a circuit pattern and an alignment mark have already been formed is sequentially overlaid and exposed using a step-and-repeat method for each shot, Each of the alignment marks formed at a plurality of locations on the wafer is sequentially aligned in a step-and-repeat manner to each reference position corresponding to the mark determined by the design of the pattern to be exposed. A positioning method for accurately performing exposure for each shikaft each time the positioning is performed, the method comprising the following steps. The group of alignment marks formed on the wafer by actually sequentially moving the wafer based on a designed reference position prior to the step-and-repeat alignment involving exposure for each shot. A process in which position measurements are performed for some of the . A step in which each composite error (ΔX, ΔY) at the position of each mark is determined from the difference between the measured value for each mark and the value at the reference position corresponding to each mark. Through statistical calculation processing using these compound errors (ΔX, ΔY), the offset error (X
_o_f_f, Y_o_f_f), expansion/contraction error (P_x,
P_y) and rotation error (θ_x, θ_y) are each determined. The obtained expansion/contraction error (P_x, P_y) is used,
A step in which the magnification error (S_M) within the shoot is determined. The determined rotation error (θ_x, θ_y) is used to determine the rotation error (S_δ) within the shot. A step in which each error determined in this way is corrected during actual positioning in a step-and-repeat method involving exposure for each shot. 3. The second aspect of the present invention is characterized by comprising a step of using the determined rotation errors (θ_x, θ_y) to determine the orthogonality error (S_ω) for each shot.
Alignment method described in section.