JP3336357B2 - Alignment device and alignment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for performing relative alignment between a predetermined surface having a plurality of regions and a reference position, and more particularly to an exposure apparatus suitable for manufacturing semiconductor elements and liquid crystal display elements. The present invention relates to an apparatus and a method for aligning a mask or a reticle with a photosensitive substrate (a semiconductor wafer, a liquid crystal plate, etc.).

[0002]

2. Description of the Related Art In recent years, in a lithography process for manufacturing a semiconductor device, a step-and-repeat type reduction projection exposure apparatus (stepper) has been frequently used as an apparatus for transferring a reticle pattern onto a wafer with high resolution. Has become. In a stepper of this type, a shorter wavelength of exposure light and a higher numerical aperture (NA) are required as the integration of semiconductor elements becomes higher.
Has recently been developed, and the resolution line width on a wafer has recently reached sub-micron (about 0.5 μm). In order to transfer such a high-resolution pattern, alignment (overlay) accuracy corresponding to the resolution is required.

At present, the alignment method of the stepper is as follows.
For example, JP-A-61-44429 or JP-A-6-44429
As disclosed in Japanese Unexamined Patent Publication No. 2-84516, extended wafer global alignment (hereinafter referred to as enhancement global alignment: EGA) has become mainstream. The EGA method refers to, for example, seven shot areas located near the center of the wafer and its outer periphery among a plurality of shot areas formed on the wafer before performing the overlay exposure on one wafer. The positions of two sets (X, Y directions) of alignment marks associated with each designated shot area are measured (sample alignment) by the alignment sensor. Thereafter, based on the position measurement values and design values of these marks,
Error parameters relating to the arrangement characteristics of the shot areas on the wafer, namely, the offset of the wafer center position (X, Y directions), the expansion / contraction degree of the wafer (X, Y directions), the remaining rotation amount of the wafer, and the orthogonality of the wafer stage (or A total of six parameters (orthogonality of shot arrays) are determined by a statistical method (least square method or the like). Then, based on the determined parameter values, the design coordinate values of all shot areas on the wafer are corrected, and the wafer stage is sequentially positioned so that the wafer is positioned at the corrected coordinate values. Is a method of stepping.

The advantage of this EGA method is that it is not necessary to measure the mark position after measuring a small number (about 3 to 16) of mark positions compared to the total number of shots on the wafer prior to wafer exposure. Therefore, unlike the conventional global alignment method, an improvement in throughput can be expected.
Alignment accuracy is extremely good for other shot areas where sample alignment was not performed, and if sample alignment is performed for a sufficient number of shot areas, individual mark detection errors can be statistically calculated. Averaging means alignment for each shot (die-by-die or site-by-site method)
The same or higher alignment accuracy can be expected for all shot regions on the entire surface of the wafer.

Here, the operation of the overlay exposure by the EGA method will be briefly described with reference to FIG. In FIG. 17, a point D is a design first (1st) exposure position of a shot area to be formed on a wafer, and a point _MAL is a first exposure position (measured value) of a shot area SA _1st actually formed on the wafer. , And the point D _EG represents the second (2nd) exposure position on the calculation calculated by the EGA calculation. In performing the overlay exposure for the shot area SA _1st , first, the 2nd exposure position (ie, the 1st exposure position D) in design is converted (corrected) by the EGA calculation (the above conversion matrix) to obtain the 2nd exposure position _DEG ( In the figure, it is represented by a vector ega). Thereafter, when the wafer stage is stepped to the second exposure position _DG for exposure, the projected image of the reticle pattern is changed to the shot area SA _1st.
Is transferred to the shot area S on the wafer.
A _2nd will be formed. In FIG. 17, the difference between the first exposure position _MAL of the shot area SA _1st measured by the alignment sensor and the second exposure position D _EG (calculated value) of the shot area SA _2nd actually formed on the wafer is shown. That is, the overlay error) is
e is exaggerated. Normally, the overlay error (vector Ve) is zero or within a predetermined allowable value (for example, about 1/5 of the minimum resolution line width), and the shot areas SA _1st and SA _2nd substantially overlap each other, and Is formed on.

[0006]

However, in the prior art as described above, even when the reticle pattern is superposed and exposed on each shot area on the wafer by using the EGA method, the reticle pattern is not applied to all shot areas. There is a problem that the overlay error (corresponding to the vector Ve in FIG. 17) cannot fall within a predetermined allowable value. this is,
Each position coordinate of the actual shot area formed on the wafer includes a random position error with respect to the design position coordinate due to the influence of a process (development processing or the like). It is considered that the detection is caused by the presence of a measurement error due to the shape distortion of the mark itself or noise included in the measurement system. However, the stepper evaluates the error amount without actually analyzing and classifying what caused the overlay error.

The present invention has been made in consideration of the above points, and has as its object to provide a positioning apparatus capable of analyzing a cause of an overlay error and further improving overlay accuracy.

[0008]

In order to solve such a problem, according to the first aspect of the present invention, at least two of a plurality of exposure regions (shot regions SAn) formed in advance on a substrate. Mark detection means (X, Y-LSA) for detecting the position of the alignment mark with respect to the area
System) and at least 2 detected by the mark detecting means.
An exposure position calculating means (EGA operation unit 502) for calculating respective exposure positions for the plurality of exposure regions based on the positions of the two alignment marks, wherein ,
An exposure area (SA _2nd ) to be overlap-exposed to at least one evaluation exposure area (SA _1st ) in accordance with a calculated exposure position of the evaluation exposure area calculated by the exposure position calculating means. Displacement (ΔV)
_Is added to a calculated exposure position (D _EG ) related to the evaluation exposure area to calculate the true exposure position (M _VE ) for evaluation, and the true exposure position (M _VE ) and a measurement exposure position (M _AL ) of the evaluation exposure area obtained by detecting the position of the alignment mark with respect to the evaluation exposure area by the mark detection means. The first error component (e) generated according to the mark detection condition when the mark detection means detects the position of the alignment mark is obtained, and the measured exposure position (M _AL ) is determined. Based on the calculated exposure position (D _EG ), a second error component (a) generated according to an exposure position calculation condition when the calculated exposure position is calculated by the exposure position calculation means is calculated. Second calculation means ( Calculation unit 505); first setting means for setting the mark detection condition to an optimal detection condition so that the first error component obtained by the second calculation means is small; and A second setting unit (LSA calculation unit 60 or EGA calculation unit 502) for setting the exposure position calculation condition to an optimum calculation condition so as to reduce the second error component obtained by the unit. I decided that. According to the ninth aspect of the present invention, the position of the alignment mark of at least two of the plurality of exposure regions formed in advance on the substrate is detected, and the detected alignment is detected. A first step of obtaining a measurement exposure position for each of the at least two exposure regions based on the position of the mark for use; and a plurality of the plurality of measurement exposure positions based on the measurement exposure positions obtained in the first step. A second step of calculating a calculated exposure position for each of the exposure areas; and at least one of the plurality of exposure areas, for the evaluation exposure area, for the evaluation calculated in the second step. By adding the amount of displacement of the exposure region to be overlaid and exposed according to the calculated exposure position for the exposure region to the calculated exposure position for the evaluation exposure region, A third step of calculating a true exposure position of the evaluation exposure area, based on the true exposure position and a measurement exposure position related to the evaluation exposure area determined in the first step, In the first step, a first error component generated according to a mark detection condition when detecting the alignment mark is determined, and the first error component is determined based on the measured exposure position and the calculated exposure position. A fourth step of calculating a second error component generated in accordance with an exposure position calculation condition when calculating the calculated exposure position in the two steps, and a step of calculating the first error component so as to reduce the first error component. A fifth step of setting the mark detection condition to the optimum detection condition and setting the exposure position calculation condition to the optimum detection condition so that the second error component is reduced.

[0009]

According to the present invention, on the substrate on which a plurality of exposure regions are formed, the true exposure position (M _VE ) of the evaluation exposure region and the mark position information (M _AL ) obtained by the mark detection means are obtained. Do not necessarily match, the mark position information (M _AL ) and the calculated exposure position (D _EG )
(In other words, the calculation parameters of the exposure position calculation means) can vary depending on the position on the substrate of the exposure region for evaluation selected from the plurality of exposure regions. The deviation of the calculated exposure position (D _EG ) from the true exposure position (M _VE ) of the region was calculated. Then, based on the shift, an error generated when detecting the position information of the mark and an error generated when calculating the exposure position are analyzed separately, and according to the analysis result, the position information of the mark is obtained. A mark detection condition for the detection or an exposure position calculation condition for the exposure position calculation means to calculate the exposure position is set.

For this reason, along with the evaluation of the alignment accuracy, the signal processing conditions (for example, the slice level) for detecting the mark position and the shot arrangement (for example, the position or the number of the exposure area for evaluation) in the statistical calculation are changed (corrected). Therefore, it is possible to analyze how each condition improves the alignment accuracy.

[0011]

FIG. 2 is a perspective view showing a schematic configuration of a reduction projection type exposure apparatus (stepper) provided with an alignment apparatus of the present invention, and FIG. 3 is a schematic view of an illumination optical system of the stepper shown in FIG. It is a perspective view which shows a structure. As shown in FIG. 3, illumination light (g-line,
The i-line and the like) are reflected by the elliptical mirror 12, then reflected by the cold mirror 13 and focused on the second focal point of the elliptical mirror 12. Further, a condensing optical system 1 including a collimator lens and the like.
The illumination light that has passed through the optical integrator 4 and the optical integrator (fly-eye lens group) 15 and has undergone uniformization of the luminous flux reaches a mirror 17 via a relay lens system 16 and is reflected substantially vertically downward here. After that, the reticle R is illuminated with almost uniform illuminance via the condenser lens 18. Note that a KrF excimer laser light source or the like may be used as an exposure illumination light source.

A reticle R serving as a projection master has a reticle R outside the circuit pattern area PA (around the reticle).
Alignment mark R for positioning
X, RY ₁ and RY ₂ are formed. The reticle R is mounted on the reticle stage 19, and is positioned such that the center point RC of the pattern area PA substantially coincides with the optical axis AX of the projection optical system 1. The reticle stage 19 is configured to be two-dimensionally movable in a horizontal plane by drive motors 21 and 22, and has a laser light wave interference type length measuring device (hereinafter, referred to as an end) at its end.
Moving mirrors 23 and 24 for reflecting the laser beams from 25 and 26 are fixed. Interferometer 25, 2
Reference numeral 6 denotes a two-dimensional position of the reticle R, for example, 0.01 μm.
It is always detected with a resolution of about m. The initial setting of the reticle R is performed using alignment marks RX, RY ₁ ,
Based on the mark detection signal from the reticle alignment system (not shown) for detecting photoelectrically RY _2, it is performed by fine movement of the reticle stage 19.

In this embodiment, two sets of patterns (a main scale pattern RP ₁ and a sub scale pattern RP ₂ ) as shown in FIG. 4 are placed near the center point RC of the reticle R, for example.
It is formed at a predetermined interval ΔY in the Y direction. still,
Regarding the configuration of two sets of pattern groups as shown in FIG.
For example, it is disclosed in JP-B-63-38697. In FIG. 4, the lattice patterns 70x are provided at a constant pitch in the X direction, and the lattice patterns 70y are provided at the same pitch as the pattern 70x in the Y direction. Each of the lattice patterns 70x and 70y has a reference number of 2, 4, 6, 8 in the positive and negative directions with the center of the pattern being 0. The lattice patterns 71x and 71y are provided as an auxiliary to the lattice patterns 70x and 70y, and function as rough verniers here. Above, the main scale pattern RP ₁ is constituted by four grid pattern, grid pattern 71x, 71y may without particularly providing. The lattice pattern 80x to form a vernier pattern RP _2, 80 y is
Its pitch grating pattern 70x, with defined slightly larger pitch than the pitch of 70y, grid pattern 70x, each bar 70y when the bar mark superimposed a main scale pattern RP ₁ and vernier pattern RP ₂ The shape is determined so as to be sandwiched between the marks. Similarly, the pitches of the grid patterns 81x and 81y acting as rough verniers are set to be slightly larger than the pitches of the grid patterns 71x and 71y, and each bar mark is sandwiched between the bar marks of the grid patterns 71x and 71y. The shape is determined.

Now, as shown in FIG.
Is incident on the one-sided (or both-sided) telecentric projection optical system 1, and the projection optical system 1 reduces the projected image of the circuit pattern of the reticle R to 1/5 or 1/10, and Is imaged and projected onto one shot area SA on the wafer W on which a resist layer is formed.
The wafer holder 2 vacuum-adsorbs the wafer W,
The wafer stage 3 is provided to be slightly rotatable with respect to the wafer stage 3 that moves two-dimensionally in the X and Y directions. The drive motor 4 is fixed on the wafer stage 3 and rotates the wafer holder 2. The wafer stage 3 is two-dimensionally moved by the drive motors 5 and 6 in a step-and-repeat manner.
When the transfer exposure of the reticle R to the upper one shot area SA is completed, stepping is performed to the next shot position. A moving mirror 7 having a reflecting plane extending in the Y direction and a moving mirror 8 having a reflecting plane extending in the X direction are fixed to two orthogonal sides of the end of the wafer stage 3. The interferometer 9 projects a laser beam onto the movable mirror 8 to
The position (or the amount of movement) in the Y direction
m, and the interferometer 10 projects a laser beam onto the movable mirror 7 to detect the position (or the amount of movement) of the wafer stage 3 in the X direction with the same resolution. Note that the optical axis AX of the projection optical system 1 is configured to pass through the intersection of the length measurement axes (center lines of the laser beam) of the interferometers 9 and 10. Although not shown in FIG. 2, the stage controller 27 (see FIG. 1) controls the movement and positioning of the wafer holder 2 and the wafer stage 3 based on position measurement signals and the like from the interferometers 9 and 10. Is configured.

In FIG. 2, an off-axis type alignment optical system (Fi-Fi) fixed at a fixed interval from the projection optical system 1 and observing an alignment mark on the wafer W in an enlarged manner.
eldImage Alignment (FIA system) 20 is also shown.
Regarding the configuration and the like of the FIA system 20, see, for example,
Since it is disclosed in Japanese Patent No. 4103, a brief description will be given here. By irradiating the wafer W with illumination light having a predetermined wavelength width, the FIA system 20 forms an image of an alignment mark on the wafer and an index mark on an index plate conjugated with the wafer by an objective lens or the like. , ITV, C
An image is formed on the light receiving surface of an image sensor such as a CD camera. The video signal VS from the image pickup device is combined with a position measurement signal from the interferometers 9 and 10 and a FIA operation unit 61 (see FIG.
Reference). The FIA operation unit 61 calculates the shift of the mark image with respect to the index mark based on the waveform of the video signal VS, and outputs to the main controller 50 information on the mark position when the mark image is located at the center of the index mark.

Further, the stepper has a wide mark detectable range (search range) and a TTL (Through The Lens) type laser step device capable of high-speed alignment measurement.
An alignment (LSA) system is provided. LS
Regarding the configuration and the like of the A system, see, for example, JP-A-60-1307.
No. 42 or the aforementioned Japanese Patent Application Laid-Open No. 2-54103.

Although not shown, a laser beam generated from a laser light source such as He-Ne or Ar ions is expanded to a predetermined beam diameter by a beam expander and shaped into an elongated elliptical beam by a cylindrical lens.
The light enters the beam splitter 30 and is split into two light beams. The laser beam that has passed through the beam splitter 30 is reflected by a mirror 31, passes through a beam splitter 32, and is converged by an imaging lens group 33 so that the cross section becomes a band-shaped spot light. The light enters a first folding mirror 34 disposed between the system 1 and the system 1 so as not to shield the projection optical path of the circuit pattern image.
The first turning mirror 34 reflects the laser beam upward toward the reticle R. The laser beam is provided below the reticle R, enters a mirror 35 having a reflection plane parallel to the surface of the reticle R, and enters the entrance pupil Ep of the projection optical system 1.
It is reflected towards the center of. The laser beam from the mirror 35 is converged from the off-axis portion of the projection optical system 1 so that the principal ray is substantially perpendicular to the wafer W.
A belt-like spot light L elongated in the X direction toward X
The image is formed as YS.

Now, the spot light LYS is projected on the wafer W by X
It is used to scan the alignment mark of a diffraction grating extending in the direction relatively in the Y direction to detect the position of the mark. When the spot light LYS irradiates the mark,
From the mark, diffracted light (first-order light or more) and scattered light are generated together with specularly reflected light (zero-order light). The optical information returns to the beam splitter 34 through the projection optical system 1, the mirror 35, the mirror 34, and the imaging lens group 33 again, is reflected there, and is spatially conjugated with the pupil Ep of the projection optical system 1. And a condensing lens. The optical element 36 transmits high-order diffracted light (for example, ± 1st to 3rd-order diffracted light) or scattered light, blocks specularly reflected light (0th-order light), and mirrors the diffracted light or scattered light. The light is condensed on the light receiving surface of the photoelectric element 38 via 37. The photoelectric element 38 outputs a photoelectric signal corresponding to the amount of condensed diffracted light or scattered light. As described above, the mirror 31, the beam splitter 32, the imaging lens group 33, the mirrors 34 and 35, the optical element 36, the mirror 37, and the photoelectric element 38 include an alignment optical system that detects the position of the mark on the wafer W in the Y direction ( Hereinafter, referred to as a Y-LSA system).

On the other hand, another laser beam reflected by the beam splitter 30 is used as an alignment optical system (hereinafter, referred to as an alignment optical system) for detecting the position of the alignment mark on the wafer W in the X direction.
X-LSA). X-LSA system is YL
Mirror 41, beam splitter 4 just like SA system
2, imaging lens group 43, mirrors 44 and 45, optical element 4
6, a mirror 47, and a photoelectric element 48, and a strip-shaped spot light LXS elongated on the wafer W in the Y direction.
Is imaged.

The photoelectric signals LS from the photoelectric elements 38 and 48 are input to an LSA operation unit 60 (see FIG. 1) described later together with the position measurement signals from the interferometers 9 and 10, and the LSA operation unit 60 The photoelectric signal LS is sampled in synchronization with an up / down pulse signal generated for every unit movement amount of 3 (0.01 μm).
Then, after converting each sampling value into a digital value and storing the digital value in the memory in the order of addresses, the position of the alignment mark is detected by predetermined arithmetic processing, and this position information is output to the main controller 50. Note that the LSA calculation unit 60 may perform the waveform processing of the photoelectric signal according to the respective intensities of the diffracted light and the scattered light in parallel, and determine the position of the alignment mark from both the detection results.

Next, referring to FIG. 1, a description will be given of a main control unit 50 for integrally controlling the entire apparatus having the above configuration. FIG.
Is a block diagram showing a schematic configuration of a control system of the apparatus according to the present embodiment, and it is assumed that the main control apparatus 50 constantly receives a position measurement signal PDS from the interferometers 9 and 10. In FIG. 1, the signal data storage unit 62 stores X, YL
The photoelectric signal LS from the SA system (the photoelectric elements 38 and 48), for example, the waveform data converted into a digital value by the LSA operation unit 60 can be stored. In FIG. 1, FIA
The video signal VS from the system 20 (imaging element) can also be stored. The alignment (ALG) data storage unit 501 can input mark position information (that is, array coordinate values M _AL n of shot areas) from both the LSA operation unit 60 and the FIA operation unit 61. The EGA operation unit 502 calculates an array coordinate value D _EG n of the shot area on the wafer W based on the mark position information stored in the ALG data storage unit 501 by a statistical operation method. Is sent to the sequence controller 504 and the storage unit 506. EG
The A operation unit 502 calculates operation parameters prior to the array coordinate values D _EG n, namely, the offset of the wafer center position (X and Y directions), the expansion and contraction degree of the wafer (X and Y directions), the remaining rotation amount of the wafer, and the wafer. The orthogonality of the stage or the orthogonality of the shot array (transformation matrices A and O described later) is also calculated, and these parameters are also stored in the storage unit 506.

An exposure (EXP) shot map data section 503 stores a designed exposure position (array coordinate value Dn) of a shot area to be exposed on the wafer, and the design value is stored in the EGA arithmetic unit 502 and the sequence controller. 504. Sequence controller 504
Determines a series of procedures for controlling the movement of the wafer stage 3 during alignment or step-and-repeat exposure based on the above data. Here, FIG.
Inside, a device (keyboard or the like) 63 for inputting commands from the operator or various measurement data (vernier measurement value ΔV or the like described later) and an analysis result (described later) of the overlay error calculated by the arithmetic unit 505 are displayed. Equipment (CRT, etc.) 6
4 is shown.

The storage unit 506 stores calculation parameters from the EGA calculation unit 502, array coordinate values D _EG n for calculating shot areas, input data from the input device 63, and the like. The calculation unit 505 also stores data (array coordinate values D _EG n and vernier measurement values ΔV calculated in the shot area) stored in the storage unit 506 and measurement data of the shot area stored in the ALG data storage unit 501. The overlay error (vector v) is analyzed for each shot area on the wafer based on the array coordinate values M _AL n, that is, the error (vector e) generated at the time of detecting the mark position and the error of the shot area to be sample-aligned on the wafer. And the error (vector a) generated at the time of the statistical operation in accordance with the position (or the number thereof) in (1), and the analysis is performed, and the analysis result (that is, the diagram of the displacement vectors v, e, and a described later) is It is displayed on the display device 64. Further, the arithmetic unit 505 determines the LSA arithmetic unit 6 according to the analysis result of the overlay error.
0 (or FIA operation unit 61) (for example, waveform analysis algorithm, algorithm
The slice level, etc.) and the EGA shot arrangement (that is, the position and number of shot areas to be sample-aligned) in the EGA arithmetic unit 502 are changed (corrected) in calculation, and the vectors (v ), (E) and (a) are calculated (details will be described later). The simulation result (the diagram of the three displacement vectors v, e, and a) in the calculation unit 505 is displayed on the display device 64 each time the signal processing condition or the condition related to the EGA shot arrangement is changed. Therefore, from the diagram displayed on the display device 64, the operator can know how the above-mentioned conditions improve the alignment accuracy. Further, the operator obtains the signal processing condition and the optimum condition of the EGA shot arrangement from the above result, and inputs these conditions from the input device 63 to the stepper (calculation unit 505), thereby obtaining the LSA calculation unit 60 and the EGA calculation unit. It is possible to set optimum processing conditions for 502. It should be noted that the above conditions are changed based on a command from the arithmetic unit 505 based on the LSA
The arithmetic unit 60 and the EGA arithmetic unit 502 perform each.

Next, a method of analyzing the overlay error in this embodiment will be described with reference to FIG. FIG. 5 is a schematic flowchart illustrating an example of the operation of the present embodiment. In this embodiment, EGA is performed using the X, Y-LSA system.
It is assumed that the overlay error generated when performing the alignment of the system is analyzed. In the stepper shown in FIG. 2, the sequence controller 504 uses the information stored in the EXP shot map data section 503, that is, the designed array coordinate values (Dxn, Dy) of the shot area SAn.
n), the wafer stage 3 is stepped, and the pattern of the reticle R (the main scale pattern RP shown in FIG. 4)
₁ ) is sequentially transferred onto the wafer W (step 10).
0).

After the 1st exposure is completed, the wafer W is carried out of the stepper and then subjected to a developing process or the like by a coater developer (not shown). As a result, a plurality of circuit patterns (shot areas SAn) and alignment marks Mx and My are formed on the wafer W in a matrix as shown in FIG. Further, the wafer W having the resist layer formed on the surface is carried into a stepper and loaded on the wafer stage 3. At this time, in the inside of the stepper, the overlapping with the shot area SAn (2nd)
In preparation for exposure, the reticle R is shifted by ΔY in the Y direction in parallel with the wafer processing. The reticle R is moved by servo-controlling the reticle stage 19 according to position measurement signals from the interferometers 21 and 22. As a result, the reticle R is accurately shifted by ΔY, and the vernier scale pattern RP ₂ (FIG. 4) is positioned at the coordinate position of the main scale pattern RP ₁ at the time of the first exposure (step 10).
1).

The wafer W loaded on the wafer stage 3 is first placed with an accuracy of several tens μm or less by a mechanical pre-alignment device (not shown).
Next, the sequence controller 504 performs pre-alignment of the wafer W using the FIA system 20 and the X-LSA system. First, the FIA system 20 includes two shot areas (for example, shot areas SA ₁₁ and SA _{12 in} FIG. 6) formed near the outer periphery of the wafer W and substantially symmetrically with respect to the center of the wafer (Y axis). The position in the Y direction is detected. On the other hand, in the X-LSA system, a shot area near the outer periphery of the wafer W and substantially equidistant from the two shot areas SA ₁₁ and SA ₁₂ (for example, the shot area S in FIG. 6)
A ₁₃ ) The position in the X direction is detected. Further, based on the mark position information of the three shot areas stored in the ALG data storage unit 501, the sequence controller 504 determines the amount of displacement (rotation error) of the wafer W with respect to the rectangular coordinate system XY defined by the interferometers 9 and 10. Is calculated). Thereafter, by driving the wafer holder 2 and the wafer stage 3 in accordance with the amount of the positional shift, the pre-alignment of the wafer W is completed. As a result, the relative displacement between the reticle R and the wafer W (shot area SAn) is corrected with an accuracy of 1 μm or less (Step 102).

By the way, even after the completion of step 102 (pre-alignment), for example, as shown in an exaggerated manner in FIG. 7, the moving coordinate system (orthogonal coordinate system XY) of the wafer stage 3 is used.
, The rotation error θ of the arrangement coordinate system αβ of the shot area SAn (rotation that could not be corrected by pre-alignment) remains. Note that FIG. 7 shows only the shot areas arranged on the α axis and the β axis.

Therefore, in the next step 103, before the EGA calculation, the mark positions of all the shot areas SAn on the wafer W are measured using the X, Y-LSA system.
The sequence controller 504 causes the wafer stage 3 to step according to the designed array coordinate values (Dxn, Dyn) of the shot area stored in the EXP shot map data unit 503, and finely moves the wafer stage 3 for each shot area. X, Y-LSA system spot light LX
S and LYS are relatively scanned with the alignment marks Mx and My. ALG than this, the original mark the position of the LSA computing unit 60 in a predetermined signal processing conditions are calculated, these position information array coordinate values _{(M AL xn, M AL yn} ) as
The data is stored in the data storage unit 501. At this time, the signal data storage unit 62 also stores the waveform data of the photoelectric signal LS output from the photoelectric elements 38 and 48 for each mark of all the shot areas SAn.

Here, the measuring operation of the LSA system will be briefly described with reference to FIG. FIG. 8 shows an example of the relative scanning between the mark Mx and the spot light LXS and the waveform of the photoelectric signal LS. As shown in FIG. 8A, the mark Mx is in the form of a diffraction grating having a constant pitch in the Y direction orthogonal to the relative scanning direction (X direction), and the mark Mx emits the spot light LXS by fine movement of the wafer stage 3. Scanning is performed so as to traverse substantially parallel. At this time, the signal LS from the photoelectric element 48 has a waveform as shown in FIG.
In the LSA operation unit 60, the signal waveform as described above is compared with a predetermined slice level Vr, and the center point of each intersection between the rising and falling slice levels Vr of the signal waveform is defined as the center position of the mark Mx in the X direction. It is determined. Although the signal waveforms shown in FIG. 8B maintain the symmetry, the signal waveforms shown in FIG.
Even if the mark has the same pitch configuration as that of FIG.
8C, an asymmetric waveform is not obtained, a clear peak is not obtained as shown in FIG.
As shown in (E), a peak which is originally one peak may cause a mountain crack. In the case of the waveform as shown in FIG. 8D, it is determined that the mark is not suitable for detecting the mark position by the waveform analysis algorithm, and may be rejected in advance. In the case of a peak cracking waveform, depending on the degree, adjacent two
1 when one peak is within a certain interval determined by the mark width
Considering one mark waveform, the mark center position can be measured by setting the slice level.

Next, the above-mentioned Japanese Patent Application Laid-Open No. 61-44429 is described.
According to the method disclosed in Japanese Patent Application Laid-Open Publication No. H10-209, array coordinate values (D _EG xn, D _EG yn) of all the shot areas SAn on the wafer W are calculated. First, EGA calculation unit 502 is the array coordinate values of all the shot areas SAn stored in ALG data storage unit 501 in step _{103 (M AL xn, M AL} yn) among the plurality of positions in the vicinity of the outer periphery of the wafer W Shot area (for example, shot areas SA _{1 to} SA ₇ in FIG. 6)
The array coordinate value of is read out. Then, the measurement on the array coordinate values of shot areas SA ₁ -SA ₇ thus read out (M _AL x
n, and M _AL yn), ALG shot map data portion 504
, The regularity of the shot arrangement on the wafer W to be aligned by the step-and-repeat method based on the design arrangement coordinate values (Dxn, Dyn), that is, the mapping relational expression shown in the following equation 1. (Determinant M _AL n = A · D n +
The transformation matrices A and O in O) are determined. However, the transformation matrices A and O in the above relational expression include, as parameters, the remaining rotation error θ, the orthogonality ω, the scaling errors Rx and Ry, and the offset errors Ox and Oy, respectively. , O is a matrix with two rows and one column.

[0031]

(Equation 1)

The transformation matrices A and O are represented by the following equations (2) and (3).

[0033]

(Equation 2)

[0034]

(Equation 3)

[0035] Here, the shot area on the wafer, the array coordinate values _{(M AL xn, M AL yn} ) on the measurement and arrangement coordinate value of the design (Dxn, Dyn) residuals against (εXn, εYn )
Exists, and the above equation 1 can be rewritten as the following equation 4.

[0036]

(Equation 4)

Therefore, the EGA calculation unit 502 determines the values of the parameters of the transformation matrices A and O by calculation (least square method) so that the above-mentioned residual terms are minimized. The conversion matrices A and O calculated as described above are stored in the storage unit 506 (step 104). Thereafter, the EGA operation unit 502 calculates the array coordinate values (D _EG xn, D _EG yn) of all the shot areas SAn on the wafer W according to the above equation (1).
Is calculated (step 105). Therefore, if the wafer stage 3 is stepped according to the coordinate values (D _EG xn, D _EG yn), the projected images of the reticle pattern are accurately superimposed and exposed on all the shot areas SAn. Here, the array coordinate values (D _EG xn, D _EG y) of the shot area calculated by the EGA calculation unit 502
n) is the sequence controller 504 and the storage unit 506
And sent to. Incidentally, the reason the array coordinate values calculated by the EGA calculation and _{(D EG xn, D EG yn} ) , in order to use the least squares method in EGA calculation, array coordinate values in the calculation (D _EG xn, D
_{This is because EG} yn) does not always coincide with the measured array coordinate values ( _MAL xn, _MAL yn) in all shot areas on the wafer (details will be described later).

Next, the sequence controller 504 overlapping previous array coordinate values _{(D EG xn, D EG yn} ) gradually the wafer stage 3 is stepped in accordance with the projected image of the reticle pattern for each shot area SAn on wafer W Exposure is performed together (2nd exposure). As a result, the sub-scale pattern is superimposed on the main scale pattern formed by the first exposure and transferred (step 106).

The wafer W 2nd exposure is completed is unloaded from the stepper, the development or the like is performed, is near the center of each shot area SAn overlapped and main scale pattern RP ₁ and vernier pattern RP ₂ A vernier is formed. Thereafter, the wafer W is carried into another set of observation apparatus (not shown), where X and main scale pattern RP ₁ and vernier pattern RP ₂ for each shot region, Y-direction position deviation amount .DELTA.Vx, delta
Vy is measured (step 107). The deviation amounts ΔVx and ΔVy measured for each shot area are input to the storage unit 506 via the input device 63 by the operator (step 108). The vernier measurement may be performed optically or visually, and the device configuration and measurement method may be any. In this embodiment, the operator vernier measurement values (ΔVx, ΔVx
Although y) is input to the main controller 50, the vernier may be observed and measured using, for example, the FIA system 20, and in this case, the operator does not need to input data. There are advantages.

Next, the arithmetic unit 505 stores the vernier measured values ΔVx and ΔVy from the storage unit 506 and the array coordinate values of the shot area formed by the second exposure, that is, the array coordinate values (D _EG xn, D _EG yn)
, The true array coordinate values (M _VE xn, M _VE yn) of the shot area formed by the first exposure are calculated. here,
The vernier measurement values ΔVx and ΔVy are misalignment of the first shot area (main scale pattern RP ₁ ) with respect to the second shot area (sub scale pattern RP ₂ ) transferred according to the calculated array coordinate values (D _EG xn, D _EG yn). It represents the quantity. Therefore, by adding the vernier measured values ΔVx and ΔVy as offsets to the calculated array coordinate values (D _EG xn and D _EG yn), the true array coordinate values (M
_VE xn, M _VE yn). The calculated array coordinate values (M _VE xn, M _VE yn) are stored in the storage unit 506 (Step 109).

Further, the arithmetic unit 508 stores a case in the storage unit 509.
Actual array coordinate values (D_EGx
n, D_EGyn), and true array coordinate values of the first shot area
(M_VExn, M_VEyn) and the ALG data storage unit 501
Arrangement coordinate value (M_AL
xn, M_ALyn), the first shot area SA_1st
And 2nd shot area SA_2ndAnd the overlay error (vector
Is analyzed for each shot area, and this analysis result is displayed.
It is displayed on the display device 64 (step 110). This state
This will be briefly described with reference to FIG. In FIG. 9, point D is
Exposure positions in the design of the first shot area (coordinate values Dxn, Dxn
yn), the point Ma is the measurement exposure in the 1st shot area (dotted line).
Light position (coordinate value M_ALxn, M_ALyn), point D_EGIs the 2nd show
Area SA _2ndActual exposure position (coordinate value D_EGxn, D_EG
yn), point Mv is the first shot area SA_1stTrue exposure position
(Coordinate value M_VExn, M_VEyn).

As is apparent from FIG. 9, the point Mv is shifted from the point D to the point D.
The vector v to the _EG represents the overlay error and the vector v
Is a vector e from the point Ma to the point Mv and a point D _EG from the point Ma.
To the vector a. Here, the vector e is a difference between the true exposure position of the 1st shot area SA _1st and the measurement value, that is, an error that may occur at the time of detecting a mark position (hereinafter, referred to as a signal processing condition in the LSA operation unit 60). LSA error). LS
As one of the causes of the A error, for example, the optimum signal processing condition for the signal waveform as shown in FIG.
It is considered that this is caused by not being set in the SA operation unit 60. The vector a is the first shot area S
A difference between the measured value of A _1st and the exposure position of the second shot area SA _2nd , that is, the 1st selected in the EGA calculation
The position of the shot area on the wafer W or the number thereof (E
Error (hereinafter referred to as E
GA error). Therefore, the overlay error (vector v) is mainly due to the LSA error (vector e) mainly due to the signal processing conditions and ESA mainly due to the EGA shot arrangement.
The arithmetic unit 505 displays the diagram of the three vectors v, e, and a for each shot area on the display device 64, and stores the analysis result in the storage unit 506. As a result, the operator can know the overlay error in all the shot areas on the wafer, and also the causes of the error (LSA error, EGA error). The display method on the display device 64 may be arbitrary. For example, only the vectors v of all the shot areas are displayed on the screen, and for a shot area having a large vector v, the area is enlarged and displayed according to an instruction of the operator. That is, three vectors v, e, and a may be displayed on the same screen.

Next, an operation (simulation) for minimizing the overlay error (vector v) will be described with reference to FIG. Here, step 100
To 109 have already been completed, the waveform data for each mark in all shot areas on the wafer is stored in the signal data storage unit 62, and the true array coordinate values (M _VE xn, M _VE xn, M _VE yn) is also stored in the storage unit 506.

In this embodiment, as shown in FIG. 9, the overlay error (vector v) can be classified into an LSA error (vector e) and an EGA error (vector a). Therefore, to minimize the overlay error (vector v):
LSA error (vector e) and EGA error (vector a)
Are minimized, in other words, the LSA operation unit 6
0 (for example, algorithm slice level voltage value, etc.) and EGA
It can be seen that it is only necessary to optimize each of the GA shot arrangements (here, the EGA shot arrangement indicates the positions and numbers of a plurality of shot areas on the wafer necessary for determining the conversion matrices A and O). . Therefore, in the present embodiment, the signal processing condition and the EGA shot arrangement are changed, and the LSA error and the EGA error under each condition are obtained by simulation.
It is assumed that the GA shot arrangement is optimized. Accordingly, in the present embodiment, it is assumed that a plurality of signal processing conditions and EGA shot arrangement conditions specified in advance by the operator are stored in the storage unit 506.

If the mark position is accurately detected in the LSA calculation unit 60, the points Ma and Mv shown in FIG.
The error (vector e) should be small. That is, evaluating the LSA error (vector e) is
The signal processing conditions of the arithmetic unit 60 are evaluated. If the LSA error is sufficiently small, it can be said that the waveform processing has been performed under appropriate conditions. Conversely, if the LSA error is large, it cannot be said that the waveform processing has been performed under appropriate conditions, and it is necessary to review the signal processing conditions. So first, L
Optimization of signal processing conditions for minimizing the SA error (vector e) will be described.

Here, the signal processing conditions in the LSA arithmetic unit 60 in this embodiment indicate a waveform analysis algorithm, an algorithm slice level, a processing gate width, and the like. Note that the processing gate width is determined around a design mark position. As the waveform analysis algorithm, for example, there are three algorithms described below. Now, in the first algorithm, after smoothing the signal waveform in the section determined by the predetermined processing gate width, this signal waveform is sliced at the level set by the algorithm slice level, and shown in FIG. 8B. As described above, when there are intersections on the left and right of the signal waveform, the center point of the intersection is detected as a mark position. In the second algorithm, after performing a smoothing of the signal waveform in a section equal to or higher than a predetermined level L ₁ (voltage value), a plurality of slice levels are set at regular intervals with a level L ₂ close to a peak value, Find the intersection at each slice level and its length. Then, based on the length at each slice level, a slice level at which the slope of the signal waveform is maximum in a portion below the level set by the algorithm slice level is selected, and the center point of the intersection at that level is selected as the mark position. Is detected. The third algorithm is
The signal waveform is sliced at the level set by the algorithm slice level, and its center point is determined as a reference position. Next, after performing smoothing of the signal waveform in a section equal to or higher than a predetermined level L ₁ (voltage value), a plurality of slice levels are set at regular intervals with a level L ₂ close to the peak value, and each slice level is set. , And the midpoint difference (that is, the difference from the center point at the adjacent slice level). Then, the region where the center point at each slice level is not far away from the previously obtained reference position and each center point is stable (that is, the midpoint difference is small and the slice level is the longest continuous Area), and a center point in the area is detected as a mark position.

First, the arithmetic unit 505 selects a predetermined signal processing condition, for example, a level value of the slice level Vr, from the storage unit 506, and changes the signal processing condition of the LSA arithmetic unit 60 (step 200). Next, the LSA operation unit 60 sequentially reads out the waveform data from the signal data storage unit 62, and under the newly set conditions (slice level), the mark positions (coordinate values M _AL xn, M _AL yn). Thereafter, the mark position information is stored in the ALG data storage unit 501 (Step 201).

Next, the arithmetic unit 505 array coordinate values obtained in step _{201 (M AL xn, M AL} yn) and the true array coordinate values read from the storage unit _{506 (M VE xn, M VE} yn) and , The LSA error (vector e) is calculated for each shot area, and the vector e of each shot area is displayed on the display device 64. The LSA error calculated in this way is stored in the storage unit 506 in association with the signal processing conditions set in the LSA operation unit 60 (Step 202). Thereafter, the arithmetic unit 505 determines whether or not simulation has been performed for all the signal processing conditions previously set in the storage unit 506 by the operator (step 203). Here, since the simulations for all the conditions have not been completed, step 20 is executed.
Return to 0. The calculation unit 505 repeatedly executes steps 200 to 202 until the simulation ends, and proceeds to the next step 204 when the simulation ends under all conditions. As the signal processing conditions set in advance in the storage unit 506, only the algorithm slice level is changed or only the waveform analysis algorithm (or processing gate width) is changed. May be set as described above, or a condition combining these may be set.

When the simulation has been completed for all the signal processing conditions, the arithmetic unit 505 stores in the storage unit 5
Based on the LSA error under each condition stored in 06, a signal processing condition that minimizes the LSA error in each shot area is selected, and this condition is set as the optimum condition in the LSA calculation unit 60 (step 204). . As a result, LS
The signal processing conditions in the A operation unit 60 are optimized, and the detection accuracy of the mark position in the LSA system is improved. In other words, under the signal processing conditions set as described above,
The point Ma shown in FIG. 9 is closest to or coincides with the point Mv.

By the way, even if steps 200 to 203 are repeatedly executed and simulation is performed under all signal processing conditions, the LSA error may not be reduced. Alternatively, even under the processing conditions set as the optimum conditions as described above, the LSA error may not be slightly small. Therefore, the calculation unit 505 calculates the LSA error in each shot area calculated under the optimal condition (the storage unit 506).
It is determined whether or not it is necessary to analyze the LSA error in more detail based on the stored (step 20).
5) If the LSA error does not become small even after repeating the simulation, it is determined that the analysis of the LSA error is necessary, and the process proceeds to the next step 206. On the other hand, the LSA in each shot area is optimized by optimizing the signal processing conditions as described above.
If the error is sufficiently small, the process immediately proceeds to step 208. Here, the calculation unit 505 may calculate a standard deviation (or an average value) from the LSA errors in all shot areas, for example, and determine whether or not this value exceeds a predetermined value. In this embodiment, LS
It is assumed that the A error has not become small, and the process proceeds to the next step 206. Therefore, the signal processing conditions in the LSA operation unit 60 are arbitrary conditions, for example, initial conditions (the conditions in step 103), or step 200.
This means that the processing conditions in the simulation performed last in steps 202 to 202 are set. Here, the calculation unit 505 determines whether analysis of the LSA error is necessary. However, the operator observes the LSA error under each condition displayed on the display device 64 and determines whether the analysis is necessary. You may do it.

Next, the calculation unit 505 analyzes the LSA error (vector e) using the linear least squares method (step 206). It should be noted that the linear least squares method is the aforementioned E
This is exactly the same method as the GA operation, and the LSA error (vector e) is converted to a linear component (hereinafter, LSA) by this operation.
This can be divided into a residual error) and a remaining component (hereinafter, referred to as a random error).

Therefore, the arithmetic unit 505 reads the true array coordinate values (M _VE xn, M _VE yn) of the shot area from the storage unit 506, and sets LS
A measured array coordinate value of the shot area detected under the signal processing conditions set in the A operation unit 60 ( _MAL x
n, M _AL yn) is read from the ALG data storage unit 501. At this time, the calculation unit 505 sets the shot area S on the wafer.
A plurality of shot areas, for example, shot areas SA _{1 to} SA ₇ (FIG. 6) are designated from An, and their coordinate values are read from each of the ALG data storage unit 501 and the storage unit 506. Thereafter, using the read array coordinate values, the calculation unit 505 determines the conversion matrices B and C in the matrix shown in the following Expression 5 by the same method as the EGA calculation (step 104), and stores the values. Stored in the section 506. Note that the transformation matrix B is a matrix of 2 rows and 2 columns, and C is a matrix of 2 rows and 1 column. The number of shot areas used for determining the conversion matrices B and C may be two or more. For example, the number of shot areas may be determined using array coordinate values of all shot areas.

[0053]

(Equation 5)

[0054] In addition, the calculating unit 505, the determined transformation matrix B, and using C and equation 5, performs the conversion of measurement on the array coordinate values of the shot area _{(M AL xn, M AL yn} ), the storage unit the converted coordinates as _{(M er xn, M er yn} ) 5
06. Thereafter, the arithmetic unit 505 stores the data in the storage unit 50.
Stored three arrays coordinate values _{6 (M AL xn, M AL} yn),
Analyze the LSA error (vector e) for each shot area based on (M _VE xn, M _VE yn) and (M _er xn, M _er yn)
This analysis result is displayed on the display device 64 (step 20).
7). This situation will be described with reference to FIG. 11, but here, only the differences from FIG. 9 will be described. Incidentally, the point M _er in FIG. 11 represents a shot position converted by Equation 5 (coordinates _{M er xn, M er yn)} .

As is apparent from FIG. 11, the LSA error (vector e) is obtained by _calculating the vector e _R from the point Ma to the point _Mer ,
It is divided from the point M _er to the vector r to the point Mv. Here, since the vector e _R is calculated by the linear least squares method, it represents the linear component (LSA residual error) of the LSA error (vector e), and the vector r is the remaining component (excluding the linear component of the LSA error) That is, a random error including a non-linear component) is represented. As a result, L
The SA error (vector e) is replaced by the LSA residual error (vector e).
_R ) and a random error (vector r). The operation unit 505 includes three vectors e, e _R , and r
Is displayed on the display device 64 for each shot area, and the analysis result is stored in the storage unit 506. At this time, the vector e _R (or r) of each shot area, only the transformation matrices B and C (or the values of each parameter), or a combination thereof may be displayed on the display device 64.

Since the LSA residual error (vector e _R ) always has a certain tendency as described above, the LSA residual error is used as it is for the measurement results of the LSA system and the LSA operation unit 60 on the actual process wafer. In other words, by updating the EGA operation result (transformation matrices A and O) with the LSA residual error (transformation matrices B and C), LS
As a result, the position detection accuracy of the A system and the LSA operation unit 60 is improved (details will be described later).

With the above operation, the LSA operation unit 6
Optimization of signal processing conditions at 0 (and analysis of LSA error)
Will end. By the way, if the signal processing conditions are optimized as described above so that the mark position can be accurately detected, the point Ma shown in FIG.
And the point D _EG approach, and the EGA error (vector a) should be small. That is, evaluating the EGA error (vector a) evaluates the accuracy of the EGA calculation. If the EGA error is sufficiently small, it can be said that the EGA shot arrangement is set to an appropriate condition. Conversely, E
If the GA error is large, it cannot be said that the EGA shot arrangement is set to an appropriate condition, and it is necessary to review the EGA shot arrangement. Therefore, next, optimization of the EGA shot arrangement for minimizing the EGA error (vector a) will be described.

The operation unit 505 stores the data from the storage unit 506.
Fixed EGA shot arrangement (number of shots and their positions)
And the EGA calculation unit 502
The layout is changed (step 208). Next, EG
The A operation unit 502 sets the newly set EGA series.
Arrangement for measurement of each shot area corresponding to the boat arrangement
Standard value (M_ALxn, M_ALyn) is the ALG data storage unit 501
From the array, and the array coordinates in design (Dxn, Dyn)
From the EXP shot map data section 503.
The array coordinate values read from the ALG data storage unit 501
(M_ALxn, M_ALyn) is set in the previous step 204
It is a value detected under the signal processing conditions. Scold
After that, the EGA operation unit 502 arranges each shot area
Coordinate value (M _ALxn, M_ALyn) and (Dxn, Dyn)
Then, the transformation matrices A and O are
decide. The calculated transformation matrices A and O are stored in a storage unit.
506 is stored. Further, the EGA operation unit 50
2 is obtained by using the calculated transformation matrices A and O and the above equation 1.
And the array coordinates of all shot areas SAn on the wafer W
Value (D_EGxn, D_EGyn), and stores the calculation result in the storage unit.
506 (step 209).

Next, the arithmetic unit 505 is calculated array coordinate values as described above _{(D EG xn, D EG yn} ) and, ALG array coordinate values read out from the data storage unit _{501 (M AL xn, M AL} yn)
Then, the EGA error (vector a) is calculated for each shot area, and the vector a of each shot area is displayed on the display device 64. The EGA error calculated in this way is stored in the storage unit 506 in association with the EGA shot arrangement set in the EGA calculation unit 502 (Step 210). Thereafter, the arithmetic unit 505 executes all EGs set in the storage unit 506 by the operator in advance.
It is determined whether a simulation (calculation of an EGA error for each shot area) has been performed for the A shot arrangement (step 211), and steps 208 to 210 are repeatedly executed until the simulation is completed.

As the EGA shot arrangement conditions set in the storage unit 506, the shot positions are determined in advance, and only by changing the number of shots or by specifying the shot position while keeping the number of shots constant. It may be simply changed, or a condition combining these may be set. By the way, when the simulation is completed for all the EGA shot arrangements, the arithmetic unit 505 determines, based on the EGA errors under each condition stored in the storage unit 506, the EGA shot arrangement in which the EGA error in each shot area is minimized. Is selected, and this arrangement is set in the EGA calculation unit 502 as an optimal condition (step 212). As a result, the EGA operation unit 5
02, in other words, under the shot arrangement set as described above, the point _DEG shown in FIG. 9 comes closest to or coincides with the point Ma, and the EGA shot arrangement Optimization is completed.

FIGS. 12 and 13 show the state of the overlay error (vector v) after the optimization of the signal processing conditions and the EGA shot arrangement. FIG. 12 shows a case where the LSA error (vector e) is sufficiently reduced by optimizing the signal processing conditions, and FIG. 13 shows a case where the LSA error (vector e) is not reduced even if the signal processing conditions are optimized. I have. As is clear from FIG. 12, when the signal processing conditions and the EGA shot arrangement are optimized,
LSA error (vector e) and EGA error (vector a)
Are sufficiently small, and accordingly, the overlay error (vector v) is also sufficiently small (or almost zero).
Become. Therefore, as long as a process wafer under the same conditions as the wafer used in the above analysis (for example, the type of wafer, the type and thickness of resist and base, and the wafer processing conditions are desirably the same) is used, By performing the mark position detection and the EGA calculation under the conditions set as described above, the overlay error in the EGA method can always be minimized or almost zero, and high-precision alignment can be realized. Becomes From the above, the optimum signal processing conditions and the EGA shot arrangement (further, the conversion matrix B,
C), and it is desirable to store these values in the storage unit 506 in association with the above conditions.

On the other hand, in FIG. 13, since the LSA error (vector e) is not small, even if the mark position is detected or the EGA calculation is performed on the actual process wafer under the above conditions, the overlap is larger than a predetermined allowable value. Alignment errors may remain. Therefore, the LSA error is not reduced, and LSA
If the SA residual error (vector e _R ) always has a certain tendency, the LSA system and the LSA
The LSA residual error is added to the measurement result by the arithmetic unit 60 as it is. In other words, the EGA calculation equation (Equation 1) calculated under the above conditions is converted into the conversion matrices B and C (step 20) determined when calculating the LSA residual error.
Update using 6). That is, the following Expression 6 is obtained from Expressions 1 and 5.

[0063]

(Equation 6)

As a result, by the EGA calculation (Equation 6), the apparent array coordinate value (point D) of the shot area is converted into the point D _EG ′, that is, the EGA calculation accuracy is improved. The overlay error (the distance between the point M _VE and the point D _EG ′) can be reduced. Expression 6 is a true array coordinate value of the shot area (M _VE xn, M _VE yn).
And the array coordinate values (Dxn, Dyn) on the design,
It goes without saying that this is exactly the same as the case of calculating the transformation matrix in the A operation expression.

As described above, in this embodiment, in order to simulate the LSA error (vector e) and the EGA error (vector a), a plurality of signal processing conditions and EGA shot arrangements specified in advance by the operator are stored in the storage unit 506. Although it is stored, for example, every time the operator (or the arithmetic unit 505) simulates the LSA error or the EGA error, the next signal processing condition or the EGA shot arrangement is determined based on the simulation result. The determined conditions may be set for the LSA operation unit 60 and the EGA operation unit 502. In this case, the LSA error or EG
There is an advantage that the number of simulations of the A error can be reduced as compared with the above embodiment.

Further, simulation of the LSA error (vector e), in particular, changing the signal processing conditions (step 20)
When performing 0), several shot areas (for example, shot areas located near the center and the outer periphery of the wafer) are selected from a plurality of shot areas on the wafer, and each shot mark of the selected shot area is selected. A signal waveform (for example, FIG. 8C) may be displayed on the display device 64. Displaying the signal waveform in this manner is useful for determining the next signal processing condition in the simulation of the LSA error, and has an effect that the number of simulations can be further reduced. Note that the number of shot areas for displaying the signal waveform may be one.

Similarly, when simulating the EGA error (vector a), particularly when changing the EGA shot arrangement (step 208), a plurality of shot areas (or on the wafer) corresponding to the EGA shot arrangement to be simulated next. From among all the shot areas, several shot areas (or all shot areas may be selected) are selected, and the LSA error (vector e), the LSA residual error (vector e _R ),
And at least one of a random error (vector r)
May be displayed on the display device 64. Such a display is useful for determining the next EGA shot arrangement in the simulation of the EGA error, and has an effect that the number of simulations can be further reduced.

In calculating the transformation matrices B and C, the LSA error (vector e) in all shot areas on the wafer (or only a plurality of shot areas SA _{1 to} SA ₇ specified in advance) may be used. Is displayed on the display device 64. Then, for example, the tendency (direction and magnitude) of the vector e is extremely different from the tendency of the entire wafer (in other words, the random error r is extremely large).
If the shot areas are excluded from the designated shots used to calculate the conversion matrices B and C in advance, the conversion matrices B and C can be calculated with higher accuracy.
If the shot area removed here is not designated as an EGA shot even when optimizing (simulating) the EGA shot arrangement, the EGA shot can be obtained.
It is possible to reduce the number of shot placement simulations, and as a result, the EGA calculation accuracy on the process wafer is improved.
The A error (vector a) is minimized.

Further, if the EGA error (vector a) does not become small even when the simulation of the EGA shot arrangement is performed, for example, the shot area on the wafer is divided into several blocks, and the EGA calculation (conversion matrix) is performed for each block. A and O), and the EGA shot arrangement may be optimized in block units. Further, for example, when the scaling error near the outer periphery of the wafer is extremely large, all the shot areas on the wafer are divided into a circular first area centered on the wafer center and an annular second area outside the area. Area (for example, an area including only the shot area located at the outermost periphery)
The optimization of the A shot arrangement may be performed using only the shot area in the first area. When an EGA calculation is performed on an actual process wafer in accordance with the EGA shot arrangement determined under such conditions, an overlay error in a shot area in the second area may increase.
In an actual process wafer, it is desirable to separately execute an EGA operation or perform alignment by a die-by-die or site-by-site method for a shot region in the second region.

Further, in the above embodiment, the storage unit 506 is used in advance.
When the simulation is completed for all the signal processing conditions and EGA shot arrangements set in
05 (or the operator) selects the optimum condition based on the simulation result stored in the storage unit 506 in association with each condition, and sets the selected condition in the LSA operation unit 60 and the EGA operation unit 502. (Steps 204 and 212). However,
For example, every time the operator (or the arithmetic unit 505) simulates the LSA error or the EGA error, the simulation result is compared with the simulation result already stored in the storage unit 506, and the simulation result is improved. That is, LSA error or EG
Only when the A error is small, the data stored in the storage unit 506 (the simulation result associated with the above condition) may be rewritten (updated). In this case, the LSA operation unit 60 is immediately operated in accordance with the data stored in the storage unit 506 without selecting the optimum conditions when all the signal processing conditions and EGA shot arrangements set in the storage unit 506 are completed. Optimum conditions can be set for the EGA calculation unit 502 and the EGA calculation unit 502. Further, since it is not necessary to store all the signal processing conditions set in the storage unit 506 and the simulation results of the EGA shot arrangement in the storage unit 506, there is an advantage that the storage capacity can be reduced. If the LSA error and the EGA error do not become small even when the simulation is performed for all the conditions, the conditions in the last simulation performed are set in the LSA operation unit 60 and the EGA operation unit 502.
At this time, it is preferable that the calculation unit 505 stores the simulation result under the last condition in the storage unit 506.

In the flowchart shown in FIG. 5, the mark positions of all the shot areas on the wafer are detected after the end of step 102. However, in step 103, it is necessary to determine the conversion matrices A and O. The mark position measurement (and storage of waveform data) may be performed only for the short shot areas, and the mark measurement and the like may be performed for the remaining shot areas in parallel with the second exposure in step 106.

Further, as disclosed in, for example, Japanese Patent Application Laid-Open No. 1-179317, if the stepper body and the coater developer (and a separate inspection device or the like) are inlined, all the operations in the above embodiment can be performed. Can be automated,
It goes without saying that the operator does not need to intervene. Also, by constructing such a system, it is possible to analyze overlay errors including (considered) processing conditions (development, etching conditions, etc.) for wafers,
In addition, optimization of signal processing conditions and EGA shot arrangement can be performed.

In the above embodiment, the EGA
Although the analysis of the overlay error in the fine alignment of the method has been described, the alignment method suitable for the present invention is not limited to the EGA method (further, the least square method), and the stepping position of the wafer stage prior to the overlay exposure. Any method other than the least squares method may be used. Even in the case of the global alignment method in which the displacements of the entire wafer in the X, Y and rotational directions are corrected collectively before exposure, the overlay error can be analyzed by the same operation as in the above embodiment. . Further, even in the method of performing alignment for each shot (die-by-die or site-by-site method), the overlay error can be analyzed by performing the same operation as in the above embodiment. . However, in the die-by-die or site-by-site method, the point D _EG in the above embodiment is used.
And the point _MAL coincide with each other, so that an error (LSA) that may occur when the mark position is detected by the alignment sensor is detected.
(Corresponding to an error), the error can be analyzed separately for the linear component and the remaining component.

In the above embodiment, the case where the LSA system is used as the alignment sensor has been described. However, the present invention can be applied to any type of alignment sensor. That is, the detection method may be any of the TTR method, the TTL method, and the off-axis method, and the detection method may be the LSA method as described above or the image processing method such as the FIA system 20. In addition, for example, a one-dimensional diffraction grating formed on a wafer is irradiated with a coherent parallel beam from two directions to form one-dimensional interference fringes on the diffraction grating. An alignment sensor of a type that photoelectrically detects the intensity of the diffracted light (interference light) (hereinafter, referred to as a laser interferometric alignment; LIA system) may be used. This system includes a heterodyne system in which a constant frequency difference is given to parallel beams from two directions, and a homodyne system without a frequency difference. In particular, the heterodyne type LIA system has a phase difference between a photoelectric signal (optical beat signal) of interference light from a diffraction grating on a wafer and an optical beat signal of reference interference light separately created from two transmitted light beams. By calculating (within ± 180 °), a positional deviation within ± (2P) / 4 of the grating pitch (2P) is detected. The detailed configuration is described in, for example, JP-A-2-227602 or JP-A-2-2723.
No. 05 and the like. The difference from the above-described embodiment when the above-described alignment sensor is used is only the signal processing conditions that can be changed at the time of optimization. Hereinafter, referring to FIG. 14 and FIG.
The signal processing conditions in each of the A systems will be briefly described.

FIG. 14A shows a state of wafer mark WM ₁ detected by FIA system 20, and FIG.
Indicates the waveform of the image signal obtained at that time. FIG.
As shown in (A), FIA system 20 (imaging element not shown)
Is electrically scanned along an image of the bar mark and index mark FM _1, FM ₂ of the three wafer marks WM ₁ to scan line VL. At this time, since only one scanning line is disadvantageous in terms of the S / N ratio, the level of the image signal obtained by a plurality of horizontal scanning lines entering the video sampling area VSA (dashed line) is determined for each pixel in the horizontal direction. It is better to add and average As shown in FIG. 14B, the image signal has a waveform portion corresponding to each of the index marks FM ₁ and FM ₂ on both sides, and the FIA operation unit 61 processes this waveform portion at the slice level SL _2. in search of the center position of each mark (position on pixels), seeking the center position x _0. Instead of obtaining the respective center positions of the index mark FM _1, FM _2, by obtaining the respective positions of the right edge and the left edge of the index mark FM ₂ of the index mark FM _1, the center position x
You may ask for ₀ . On the other hand, here, FIG.
As shown in FIG. 4B, the waveform on the image signal has a bottom at a position corresponding to the left edge and the right edge of each bar mark, and the FIA operation unit 61 determines the slice level SL.
After determining the center position of each bar marks performs waveform processing by _1, it calculates the center position x _C of the wafer mark WM ₁ by averaging the positions. Further, the difference Δx (= x ₀ −x _C ) between the previously obtained position x ₀ and the mark measurement position x _C is calculated, and the wafer when the wafer mark WM ₁ is positioned in the observation area of the FIA system 20 is calculated. A value obtained by adding the position of the stage 3 and the difference Δx is output as mark position information.

Therefore, the signal processing conditions that can be changed in the FIA system 20 as described above include a waveform analysis algorithm, a slice level SL ₁ (voltage value), a contrast limit value, and a processing gate width Gx (width Gx on a pixel) Center position and its width). Further, as a waveform analysis algorithm, when obtaining the center position of each bar mark, of the outer slope BS _1L , BS _1L , BS _1R and BS _2L , BS _2R corresponding to the left edge and the right edge of the bar mark, There is a mode using only BS _2R , a mode using only inner slopes BS _1R and BS _2L , a mode using outer slopes BS _1L and BS _2R , and a mode using inner slopes BS _1R and BS _2L .

Next, signal processing conditions in the LIA system (particularly, the heterodyne system) will be described with reference to FIG.
As shown in FIG. 15, the one-dimensional diffraction grating WM on the wafer
For _two, the two coherent beams (parallel light flux) BM _1, BM ₂ frequency difference Δf is incident at an intersection angle (2ψ _0), is on the diffraction grating WM ₂ pitch P (However, the grating pitch 2P) Is produced. This interference fringe IF has a frequency difference Δf in the pitch direction of the diffraction grating WM _2.
And the speed V is V = Δf
Is represented by the relational expression P. As a result, the diffraction grating WM ₂
From FIG. 15, diffracted light B ₁ (-1), B ₂ (+1),
.. Occur. The suffixes 1 and 2 indicate the incident beam B
M ₁ and BM ₂ are indicated, and the number in parentheses indicates the diffraction order. Normally, in the LIA system, a reference signal separately generated from the photoelectric signal of the interference light of ± 1st-order diffracted light B ₁ (-1) and B ₂ (+1) traveling along the optical axis AX, and two transmitted light beams The position shift is detected by obtaining the phase difference between the interference signal and the photoelectric signal. Or 0-order diffracted light B ₂ (0) and −2
The amount of displacement detected from the phase difference between the photoelectric signal of the interference light with the second-order diffracted light B ₁ (-2) and the reference photoelectric signal, the zero-order diffracted light B ₁ (0) and the _second-order diffracted light B ₂ (+ The position shift amount may be obtained by adding and averaging the position shift amount detected from the phase difference between the photoelectric signal of the interference light with 2) and the reference photoelectric signal.

Therefore, it can be changed in the LIA system as described above.
The signal processing conditions are the interference light to be photoelectrically detected (the next
Number). That is, ± 1 order in LIA system
Diffracted light B₁(-1), B_Two1st mode using (+1), 0 next time
Origami B_Two(0) and the second-order diffracted light B ₁(-2), and zero-order diffracted light
B₁(0) and the second-order diffracted light B_TwoThe second mode using (+2),
Further, the intensity of the interference light in the first mode and the second mode is reduced.
Compare and use the one with the larger intensity value.
There are three modes. When optimizing the LIA system, these three modes are used.
Change the two modes to perform the simulation.
You.

In this embodiment, the true array coordinate values (M _VE
xn, M _VE yn), a vernier for visual observation (FIG. 4) was used. For example, two sets of patterns as shown in FIG. 16, that is, main scale patterns (RX _1a , RX _1b )
And (RY _1a , RY _1b ) and the vernier pattern (RX _2a , RX
_2b ) and (RY _2a , RY _2b ), the positional deviation amounts (ΔVx, ΔVy) of the two can be inspected independently of each other in a separate inspection device (and an alignment sensor of a stepper).
Can be automatically measured, and the measurement accuracy can be improved. Regarding measurement technology using this type of pattern,
For example, since it is disclosed in JP-A-2-31142, the description is omitted here. In FIG. 16, a state in which the sub-scale pattern is superimposed on the main scale pattern is indicated by a dotted line. For example, the positional deviation amount ΔVx in the X direction is
By measuring the distance Ly of the intersecting portion (hatched portion), it is calculated from the relational expression of ΔVx = (LY−Ly) / 2 · tan (α / 2). Here, LY is a distance (design value) when the main scale pattern and the sub scale pattern are accurately overlapped without being displaced in the X direction. Also, without using the pattern group shown in FIG. 16, for example, a diffraction grating mark Mx as shown in FIG. 8A is used for both the main scale pattern and the sub scale pattern, and the two are separated by a predetermined distance (design value). When the image is transferred onto the wafer at a distance only, the distance between the two is measured and the difference from the design value is obtained, whereby the amount of positional deviation can be automatically measured in the same manner as described above.

In the above embodiment, only the optimization of the signal processing conditions in the LSA system has been described. However, for the same process wafer, the optimization of the signal processing conditions is also performed in the FIA system or the LIA system. By selecting an alignment sensor that minimizes the error corresponding to the vector e in the embodiment and storing this alignment sensor in the storage unit 506 in association with the type of the process wafer, it is possible to further improve the overlay accuracy. Becomes possible. In the above embodiment to form a main scale pattern RP ₁ and vernier pattern RP ₂ in the same reticle, but it was decided to perform overlay exposure by moving the reticle by a predetermined distance, of course the two Patterns may be formed on separate reticles, and reticle exchange may be performed before overlapping exposure. Further, even when forming the main scale pattern RP ₁ and vernier pattern RP ₂ in the test reticle, or to form a portion of the device reticle (e.g. multi-die In the reticle street line corresponding region) It does not matter.

Further, in the above embodiment, when the exposure is completed, the wafer is developed and etched, and various measurements (for example, vernier measurement, mark position measurement, etc.) are performed using the pattern formed on the underlayer on the wafer. For example, a mark or vernier image (latent image) formed by performing double exposure on the resist layer, or a mark or a mark formed by performing only development processing on the wafer. Various measurements may be performed using the vernier resist image. Here, when a latent image is used, the second exposure is performed after a mark image (latent image) formed by the first exposure is detected by the alignment sensor, whereas when a resist image is used, the first exposure and the second exposure are performed. When the second exposure is completed, development processing is performed, and various types of formation are performed using the resulting resist images. In other words, when a resist image is used, the mark image formed on the resist layer by the first exposure is also exposed by the second exposure, and a resist image of the mark may not be formed even if the development process is performed. Therefore, in such a case, when performing the second exposure, a light-shielding layer (chrome or the like) is formed in advance in a partial area of the reticle corresponding to the mark image formed by the first exposure, or a reticle in the illumination optical system. It is necessary to drive a variable blind disposed in a plane substantially conjugate with the reticle to shield the area of the reticle from light so that the mark image of the resist layer is not exposed.

In the above embodiment, the vernier measurement (step 107) is performed to determine the true coordinate position M _VE of the first shot area, whereby the overlay error (vector v) and the LSA error (vector e) and the EGA are calculated. The analysis was performed separately for the error (vector a). Here, when the vernier measurement is not performed, for example, the point M _VE shown in FIG.
_Will match the point _MAL . However, even in such a case, if a simulation is performed under the above signal processing conditions, the points M _VE and M _AL approach each other, and the tendency of the change of the LSA error (vector e) according to the above conditions can be known. . Therefore, in the present invention, the vernier is not necessarily required, and the signal processing conditions can be optimized without performing the vernier measurement.

The case where the positioning apparatus according to the present invention is applied to a stepper has been described. However, an exposure apparatus other than the stepper (an X-ray exposure apparatus, an electron beam exposure apparatus having a plurality of divided masks, etc.), a step and The same effect as that of the present embodiment can be obtained by applying the present invention to an apparatus for sequentially inspecting in a repeat system or an apparatus for irradiating a part of the elements on a wafer with a laser beam to repair defective elements. .

[0084]

As described above, according to the present invention, the analysis (evaluation) of the overlay (alignment) accuracy can be calculated separately for the error generated when detecting the mark position and the error generated when calculating the exposure position. It is possible to know the cause of the occurrence in more detail. Further, since the error generated when detecting the mark position and the error generated when calculating the exposure position can be analyzed independently, it is possible to further improve the alignment accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a schematic configuration of a control system of a reduction projection type exposure apparatus provided with an alignment apparatus of the present invention.

FIG. 2 is a perspective view showing a schematic configuration of a reduction projection type exposure apparatus provided with an alignment apparatus of the present invention.

FIG. 3 is a perspective view showing a schematic configuration of an illumination optical system of the reduction projection type exposure apparatus shown in FIG.

FIG. 4 is a plan view showing an example of a configuration of a main scale pattern and a sub scale pattern formed on a reticle.

FIG. 5 is a schematic flowchart illustrating an example of an operation of analyzing a registration error according to the embodiment of the present invention.

FIG. 6 is a plan view showing a state of a plurality of shot regions formed on a wafer.

FIG. 7 is a diagram provided for describing an EGA calculation.

FIG. 8 is a view for explaining a state of mark position measurement by the LSA system.

FIG. 9 is a view for explaining a state of an analysis result of an overlay error according to the embodiment of the present invention.

FIG. 10 is a schematic flowchart showing an example of an operation for minimizing an overlay error in the embodiment of the present invention.

FIG. 11 is a view for explaining an analysis result of an LSA error according to the embodiment of the present invention.

FIG. 12 is a view for explaining signal processing conditions at the time of mark position detection and an overlay error when optimizing EGA shot arrangement in statistical calculation in the embodiment of the present invention.

FIG. 13 is a view for explaining a state of an overlay error when a large LSA error remains in the embodiment of the present invention.

FIG. 14 is a view for explaining a state of mark position measurement by the FIA system.

FIG. 15 is a view for explaining how mark positions are detected by the LIA system.

FIG. 16 is a diagram showing another example of a main scale pattern and a sub scale pattern formed on a reticle.

FIG. 17 is a diagram provided for explanation of a conventional technique.

[Description of Signs] 3 wafer stage 9, 10 interferometer 60 LSA calculation unit 61 FIA calculation unit 62 signal data storage unit 63 input device 64 display device 501 alignment data storage unit 502 EGA calculation unit 503: Exposure shot map data section 504: Sequence controller 505: Calculation section 506: Storage section W: Wafer

Claims (12)

(57) [Claims] 1. A mark detecting means for detecting a position of a registration mark for at least two exposure areas among a plurality of exposure areas formed in advance on a substrate; and at least two mark areas detected by the mark detecting means. An exposure position calculating unit configured to calculate respective exposure positions for the plurality of exposure regions based on the position of the alignment mark, wherein at least one of the plurality of exposure regions
The exposure area is calculated by the exposure position calculation means.
The calculated exposure position for the evaluation exposure area
The amount of misalignment of the exposure area
By adding to the computational exposure position to an exposure area for the serial evaluation, a first calculating means for calculating the true exposure position of the exposure region for the evaluation, and the true exposure position, exposure for the evaluation The mark detection unit determines the position of the alignment mark based on the measurement exposure position of the evaluation exposure region obtained by detecting the position of the alignment mark with respect to the area by the mark detection unit. A first error component generated according to a mark detection condition at the time of detection is obtained, and
On the basis of the measured exposure position and the calculated exposure position, a second error component generated according to an exposure position calculation condition when the calculated exposure position is calculated by the exposure position calculation means is calculated. A second calculating means for obtaining; a first setting means for setting the mark detecting condition to an optimum detecting condition so that the first error component obtained by the second calculating means is small; A second setting unit that sets the exposure position calculation condition to an optimum calculation condition so that the second error component obtained by the calculation unit is reduced. 2. The method according to claim 1, wherein the positional shift amount is obtained by aligning the second pattern with the first pattern formed in advance in the exposure area for evaluation in accordance with the calculated exposure position.
The positioning device according to claim 1, wherein the positioning device is obtained by projecting . 3. A display device for displaying a result calculated by the first calculation device and the second calculation device, wherein the first setting device can change the mark detection condition to a condition different from each other. The second setting means can be changed to the exposure position calculation conditions of different conditions, and the display means displays a display each time the mark detection condition is changed by the first setting means. 3. The positioning apparatus according to claim 2, wherein the display is updated each time the exposure position calculation condition is changed by the second setting unit. 4. The apparatus according to claim 1, wherein said first calculating means and said second calculating means determine a first exposure value between said true exposure position and said calculated exposure position.
Calculating a displacement vector, a second displacement vector between the true exposure position and the measured exposure position, and a third displacement vector between the measured exposure position and the calculated exposure position. The display means comprises: the first displacement vector and the second displacement vector;
4. The apparatus according to claim 3, wherein a diagram of the first, second, and third displacement vectors is displayed so that the sum of the displacement vector and the third displacement vector becomes the third displacement vector. 5. . 5. The method according to claim 1, wherein the first setting unit sets a detection condition that minimizes the error component from a plurality of mark detection conditions as the optimum detection condition. The positioning apparatus according to any one of claims 1 to 4, wherein a calculation condition that minimizes the error component is set from among a plurality of calculation conditions as the calculation condition. 6. The apparatus according to claim 1, wherein said first calculation means and said second calculation means further analyze said first error component based on said true exposure position and said measured exposure position. The positioning device according to claim 4 or 5, wherein 7. The mark detection means captures an image of the alignment mark, detects a position of the alignment mark based on an image signal obtained by capturing the image, and the mark detection condition is: 7. The positioning apparatus according to claim 1, wherein the signal processing condition is a signal processing condition of the image signal. 8. The exposure position calculation condition is a number of the exposure regions or a position of the exposure region when the at least two exposure regions are selected from the plurality of exposure regions. The positioning device according to any one of claims 1 to 6. 9. A plurality of exposure areas formed in advance on a substrate, wherein the positions of the alignment marks of at least two exposure areas are detected, and the detected positions of the alignment marks are detected.
Based on, its for the at least two exposed areas
A first step of determining an exposure position on each measurement, and at least two exposure areas determined in the first step.
A second step of calculating a calculated exposure position for each of the plurality of exposure regions based on the measurement exposure position with respect to the plurality of exposure regions ;
The evaluation calculated in the second step for the exposure area
Weight according to the calculated exposure position for the exposure area for
The displacement amount of the exposure area to be subjected to the joint exposure is used for the evaluation
A third step of calculating a true exposure position of the exposure area for evaluation by adding the calculated exposure position to the calculated exposure position of the exposure area; and A first error component generated according to a mark detection condition at the time of detecting the alignment mark in the first step is obtained based on the measurement exposure position with respect to the exposure area for evaluation, Calculating a second error component generated according to an exposure position calculation condition when calculating the calculated exposure position in the second step, based on the exposure position and the calculated exposure position. Four steps: setting the mark detection condition to an optimal detection condition so that the first error component is reduced; and setting the exposure position calculation condition to an optimal detection condition so that the second error component is reduced. For detection conditions Alignment method characterized by having a fifth step of constant. 10. A detection condition for minimizing the error component among a plurality of mark detection conditions is set as the optimum detection condition, and a plurality of exposure position calculation conditions are set as the optimum calculation condition. The alignment method according to claim 9 , wherein a calculation condition that minimizes the error component is set. 11. The mark detection condition is a signal processing condition of an image signal obtained by imaging the alignment mark when detecting the position of the alignment mark. The alignment method according to claim 9 or claim 10 . 12. The exposure position calculation condition is a number of the exposure regions or a position of the exposure regions when selecting the at least two exposure regions from the plurality of exposure regions. The alignment method according to claim 9 or claim 10 .