JP2003059809A - Method of exposure, and method for manufacturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of exposure capable of suppressing overlay errors from occurring, when exposing different layers on a wafer. SOLUTION: Position information of marks, formed in a specific plurality of zoned regions including either zoned region between rows and columns of a plurality of zoned regions formed on a wafer in matrix, are respectively obtained (step 409). Information on rotational error and perpendicularity error of shot region as a specific type of transfer error about either by each row and by each column of matrix is obtained, based on the position information of the mark (step 413); and the pattern of mask are sequentially transferred in a plurality of zoned regions, while compensating respectively by each row and each column of the matrix, in using the information of the specific type of transfer error for a specific type of transfer error.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure method and a device manufacturing method, and more particularly, to an exposure method used in a lithography process for manufacturing a semiconductor device, a liquid crystal display device and the like, and the exposure method. The present invention relates to a device manufacturing method.

[0002]

2. Description of the Related Art In an exposure process using a projection exposure apparatus for manufacturing a semiconductor device or the like, a wafer such as a resist or a substrate such as a glass plate (hereinafter also referred to as "wafer" as appropriate) is usually coated. Multilayer circuit patterns are superimposed and transferred, but if the overlay accuracy between each layer is poor, the semiconductor element or the like cannot satisfy the predetermined circuit characteristics,
It may result in defective products, leading to a decrease in product yield.

Therefore, in order to accurately superimpose a mask or reticle (hereinafter referred to as "reticle") on which a circuit pattern is drawn and a pattern already formed on the wafer, in the exposure process, An alignment mark is attached to each of a plurality of shot areas in advance, and the mark position (coordinate value) on the stage coordinate system (generally defined by the measurement axis of a laser interferometer that measures the position of the wafer stage) And then aligning one shot area on the wafer with the reticle pattern based on this mark position information and the projection position information of the known reticle pattern (which is measured in advance). Is performed.

In the projection exposure apparatus, as a wafer alignment method, alignment marks of only some shot areas on the wafer are detected and the regularity of the arrangement of the shot areas is obtained in consideration of the throughput, so that each shot area is arranged. The mainstream is the global alignment method for aligning. And this global
As one of the alignment methods, for example, Japanese Patent Laid-Open No. 6-3
As disclosed in Japanese Patent Publication No. 49705, there is a so-called intra-shot multipoint EGA (enhanced global alignment) method in which the regularity of the arrangement of shot areas on a wafer is precisely specified by a statistical method.

The multi-point within-shot EGA method is provided with a reference point in each shot area on one wafer, and the reference point is set as the origin in each shot area.
Each alignment mark is formed, and the coordinate values on the stage coordinate system of five or more (in the case of a two-dimensional mark) alignment marks selected from three or more shot areas are measured, and from these measured values, After calculating the position coordinates (arrangement of shot areas) of all shot areas on the wafer using statistical calculation processing (such as the least square method), the wafer stage is stepped according to the calculated arrangement of the shot areas. is there.

Here, a brief description will be given of a method of statistical calculation processing performed by the multi-point within shot EGA method.
Selected alignment mark AM _N (N =
1, 2, ..., M) (n ≧ 1, 2, ...), to which the shot point SA _n (n = 1, 2, ...) Of the reference point is designed, the design coordinate value is (Cx _{N, n} , Cy _{N). , N} ), and the relative design value of the alignment mark AM _N with respect to the reference point is (Sx _{N, n} , Sy _{N, n} ), and the calculated coordinate value of the alignment mark AM _{N on} the stage coordinate system. (Fx
_{For N, n} , Fy _{N, n,} a linear model as shown by the following equation (1) is assumed.

[0007]

[Equation 1]

Further, the actually measured coordinate values (FMx _{N, n} , FMy _{N, n} ) of each alignment mark AM _N.
And the sum of squares E of the difference between the calculated coordinate values (Fx _{N, n} , Fy _{N, n} ) is expressed by the following equation (2).

[0009]

[Equation 2]

Therefore, parameters a, b, c, d, e, f, g, h, i and j that minimize the equation (2) are calculated. Then, the position information of each shot area is calculated from the calculated parameters a to j, the design position information of the reference point in each shot area, and the design relative position information of the alignment mark with respect to the reference point. .

In the above description, the parameters a to j are used for simplification of description, but each of these parameters is the following 10 error parameters, that is, the rotation error of the wafer and the wafer. In the X and Y directions (linear expansion and contraction of the wafer), orthogonality error of the stage coordinate system, offset in the X and Y directions of the wafer, rotation error of the shot area, orthogonality error of the shot area, X and Y of the shot area. This corresponds to a predetermined combination or replacement of directional scaling (linear expansion / contraction of the shot area). In other words, the above 10 error parameters can be obtained by obtaining the parameters a to j. In addition, using the statistical calculation processing described above,
Hereinafter, the calculation method for obtaining the individual error parameters is referred to as “in-shot multipoint EGA calculation” for convenience.

[0012]

In the case where the same exposure apparatus is used when the multilayer circuit patterns are superposed and sequentially transferred onto the wafer, the above-mentioned multipoint EGA within a shot is used.
By performing wafer alignment by the method, it is possible to accurately obtain the arrangement of the shot areas in which the patterns up to the front layer to be superimposed are formed. Further, when there is a transfer error in the shot area, for example, a so-called magnification error in which the size of the shot area is different from a designed value, in consideration of linear expansion / contraction of the shot area among the error parameters, for example, the projection optical system By adjusting the projection magnification of 1 before exposure, the magnification error can be accurately corrected. However, when the reticle pattern is transferred by superimposing it on the pattern up to the front layer using an exposure device different from the exposure device used to transfer the pattern up to the front layer to be superimposed,
Even if the wafer alignment is performed by the multi-point EGA method within a shot, for example, a rotation error in the shot area or an orthogonality error in the shot area cannot be completely corrected, and a residual error may occur. This is due to the difference in the exposure apparatus.

Here, the residual error caused by the difference of the exposure apparatus will be specifically described. As an example, a length measurement system used for measuring the position of a wafer, which is provided in a scanning projection exposure apparatus (scanning stepper) that exposes layers to be superposed, uses interference of laser light. The position of the wafer in the X direction during scanning exposure is measured by the laser light reflected by the X reflecting mirror (X moving mirror), and the X of the wafer is measured based on the position information.
The directional position shall be controlled. In this case, if the X-moving mirror is not flat and is deformed into a shape exaggeratedly shown in FIG. 8A as an example, and a so-called mirror bending is present, the position of the wafer in the X-direction is changed. The erroneous control causes an orthogonality error in each shot area as shown in FIG. 8 (B). Here, each shot area is arranged into an array B _{i, j} (i = 1, 2, ..., J = 1, 2, ...)
8B, when comparing shot areas (for example, B _1,6 and B _1,12 ) arranged in the same row, as shown in FIG. 8B, the orthogonality errors are almost the same, but different. Shot areas arranged in rows (for example, B
₂ , ₁₂ and B _3,12 ) are compared, the orthogonality error may be different.

In the shot areas arranged in the same row, the position information in the X direction of the wafer is measured by the laser light reflected by the same portion on the reflecting surface of the X moving mirror. This is because the position information in the X direction of the wafer is measured by the laser beams reflected by different portions on the reflecting surface of the X moving mirror in the shot areas arranged in different rows.

Conventionally, since the transfer error in all shot areas shows the same tendency, the information of the rotation error and the orthogonality error of the shot area is obtained, and the overlay error is superposed based on this information. When transfer is performed, in the case of the above specific example, the residual error becomes large and the overlay accuracy becomes poor.

Further, in the future, semiconductor elements will be further integrated, and with this, it is certain that the overlay accuracy required for the exposure apparatus will become more and more severe. further,
In order to improve productivity, it is highly possible that multiple layers will be used to expose different layers on the substrate. Considering the allowable total overlay error in the future, the overlay error caused by the above residual error will occur. The error is no longer negligible.

The present invention has been made under the above circumstances, and a first object thereof is to provide an exposure method capable of suppressing an overlay error that occurs when exposing different layers on a substrate. To do.

A second object of the present invention is to provide a device manufacturing method capable of improving the productivity of highly integrated devices.

[0019]

According to a first aspect of the present invention, there is provided an exposure method for transferring a pattern formed on a mask onto a substrate, which comprises a plurality of substrates formed in a matrix arrangement on the substrate. Obtaining position information of marks formed in a plurality of specific partitioned areas including one partitioned area of each row and each column of the matrix among the partitioned areas; and based on the positional information of the marks. And obtaining information of a specific type of transfer error relating to a divided area for each row or column of the matrix; using the information of the transfer error for the specific type of transfer error And a step of sequentially transferring the pattern of the mask to the plurality of divided areas while performing correction for each column or each column.

According to this, information of a specific type of transfer error is obtained for each row or each column, and a mask pattern is formed in each divided area while correcting for each row or each column based on the information of the transfer error. It is being transferred in sequence. Therefore, for example, when a mask pattern is superimposed and transferred to each divided area, even if the transfer error of a specific type related to the divided area differs for each row or column of the matrix, the residual error is further reduced compared to the conventional method. As a result, it is possible to accurately transfer the patterns by superimposing them on the respective partitioned areas.

In this case, as in the exposure method according to the second aspect, the method further includes the step of obtaining information on the transfer error other than the specific type regarding the divided area by statistical calculation based on the position information of the mark. At the time of transferring the mask pattern, the transfer error other than the specific type may be corrected based on the transfer error information other than the specific type.

In each of the exposure methods described in claims 1 and 2, as in the exposure method described in claim 3, the information of the transfer error of the specific type is obtained by a statistical calculation process using the position information of the mark. You may ask.

The invention described in claim 4 is an exposure method for transferring a pattern formed on a mask onto a substrate in lot units, wherein each of n (n is a natural number) substrates from the beginning of the lot. Position information of marks formed in a plurality of specific partitioned areas including one partitioned area in each row and each column of the matrix among a plurality of partitioned areas formed in a matrix on the substrate And a step of obtaining information on a specific type of transfer error relating to a partitioned area for each row or column of the matrix based on the position information of the mark; all substrates in the lot On the other hand, at least the transfer error of the specific type is corrected using the information of the transfer error of the specific type for each row or column of the matrix while A step of sequentially transferring the pattern of the mask with the image region; an exposure method comprising.

According to this, the information of the transfer error of a specific type is obtained for each row or each column, and the mask pattern is formed in each divided area while correcting each row or each column based on the information of the transfer error. It is being transferred in sequence. So, for example,
When the mask pattern is superimposed and transferred to each divided area, the residual error can be further reduced compared to the conventional method even if the transfer error of a specific type regarding the divided area is different for each row or column of the matrix. As a result, it is possible to accurately superimpose and transfer the pattern on each divided area. Further, since the information of the specific type of transfer error obtained for the n substrates from the beginning of the lot is used for all the substrates in the lot, the information of the specific type of transfer error can be obtained with high accuracy. At the same time, the throughput can be improved.

In this case, as in the exposure method according to the fifth aspect, the method further includes a step of obtaining transfer error information other than the specific type regarding the divided area by statistical calculation based on the position information of the mark. At the time of transferring the mask pattern, the transfer error other than the specific type may be corrected based on the transfer error information other than the specific type.

In each of the exposure methods described in claims 4 and 5, the n is 2 as in the exposure method described in claim 6.
As described above, the information of the specific type of transfer error regarding the divided area for each row or column of the matrix is statistically calculated using the position information of the marks obtained for the n substrates from the lot head. It may be determined by the processing.

According to a seventh aspect of the present invention, there is provided an exposure method for exposing different layers on a substrate by using a plurality of exposure devices for transferring a pattern formed on a mask onto the substrate. A step of individually transferring the mask pattern onto a plurality of substrates by using respective exposure devices to form a plurality of divided areas on each substrate in a matrix arrangement; and a matrix arrangement on each substrate. A step of respectively obtaining position information of marks formed in a plurality of specific partitioned areas among the plurality of partitioned areas formed; and a specific type of partitioned area related to the partitioned areas based on the positional information of the marks obtained for each substrate. A step of obtaining transfer error information for each substrate and storing it as information of a specific type of transfer error relating to a divided area of the exposure device corresponding to each substrate; Transfer error of the specific type relating to the specific exposure apparatus that has performed exposure of the layer to be superposed among the layers up to the front layer of the substrate to be exposed when performing superposed exposure using the exposure apparatus of While correcting the transfer error of the specific type in consideration of the information of 1., the pattern of the mask is superposed on the transfer region arranged in a matrix on the substrate to be exposed and transferred sequentially.
Is an exposure method including.

According to this, for a plurality of exposure apparatuses, information of a specific type of transfer error regarding a divided area for each exposure apparatus is obtained and stored in, for example, a storage device. Then, when performing the transfer by superimposing, the information of the transfer error of the specific type in the specific exposure apparatus that has exposed the layer to be superposed is read, and the pattern is transferred in consideration of the information. There is. Therefore, the overlay accuracy can be improved without reducing the throughput.

The invention according to claim 8 is an exposure method for exposing different layers on a substrate by using a plurality of exposure devices for transferring a pattern formed on a mask onto a substrate. A step of individually transferring the mask pattern onto a plurality of substrates by using respective exposure devices to form a plurality of divided areas on each substrate in a matrix arrangement; and a matrix arrangement on each substrate. A step of respectively obtaining position information of marks formed in a plurality of specific partitioned areas among the plurality of partitioned areas formed; and a specific type of partitioned area related to the partitioned areas based on the positional information of the marks obtained for each substrate. A step of obtaining transfer error information for each substrate and storing it as information of a specific type of transfer error relating to a divided area of the exposure device corresponding to each substrate; When performing the exposure using the exposure apparatus of, the information of the transfer error of the specific type concerning the specific exposure apparatus used for the exposure of the specific layer after the next layer of the substrate to be exposed is taken into consideration. A step of sequentially transferring a mask pattern onto the substrate to be exposed while forming a plurality of divided areas in a matrix arrangement while correcting a transfer error.

According to this, for a plurality of exposure apparatuses, information of a specific type of transfer error regarding the divided area of each exposure apparatus is obtained and stored in, for example, a storage device. Then, when performing exposure using an arbitrary exposure apparatus of the plurality of exposure apparatuses, a transfer error of a specific type relating to a specific exposure apparatus used for exposure of a specific layer after the next layer of the substrate to be exposed is performed. Information is read out, and a transfer error of a specific type is corrected in consideration of a transfer error of a specific type that occurs during exposure of a specific layer based on the transfer error information. It is possible to improve the overlay accuracy with the layers.

In each of the exposure methods described in claims 7 and 8, as in the exposure method described in claim 9, the specific plurality of partitioned areas are formed in a matrix arrangement on each of the substrates. Of the plurality of partitioned areas, the plurality of partitioned areas include one partitioned area in each row and each column of the matrix, and a specific type of transfer error relating to the partitioned area of the exposure apparatus corresponding to each substrate. The information may include information on a specific type of transfer error relating to the divided area for each row or column of the matrix, which is obtained based on the position information of the marks of the specific plurality of divided areas. .

In each of the exposure methods described in claims 7 to 9, as in the exposure method described in claim 10, the specific plurality of partitioned areas are all partitioned areas on each of the substrates, Each partitioned area based on the measured positional information of each mark and the positional information of each partitioned area used for alignment with a predetermined point obtained by performing statistical processing calculation using the positional information of the mark The step of obtaining a non-linear component of the amount of positional deviation of the exposure apparatus and storing it as a correction value for the non-linear component of the amount of positional deviation of the exposure apparatus corresponding to each substrate. When performing exposure using the divisional area, in addition to the information on the transfer error of the specific type of the specific exposure apparatus, the correction value for the non-linear component of the positional deviation amount of the specific exposure apparatus is also taken into consideration. While correcting the transfer error and the positional deviation amount of fixed type, it is also possible to sequentially transfer the pattern of the mask to the plurality of divided areas.

An eleventh aspect of the present invention is an exposure method for transferring a pattern formed on a mask onto a substrate in lot units, and for each of n (n is a natural number) substrates from the beginning of the lot. Measuring the position information of the marks formed respectively corresponding to the plurality of divided areas formed in a matrix arrangement on the substrate; and the measured position information of the marks and the marks of the marks. Determining a non-linear component of the positional deviation amount of each of the divided areas based on the positional information of each of the divided areas used for alignment with a predetermined point obtained by performing a statistical processing calculation using the positional information; Obtaining information on a specific type of transfer error relating to a divided area for each row or column of the matrix based on the measured position information of the marks; For all the substrates in the matrix, at least the transfer error of the specific type is corrected for each row or column of the matrix by using the transfer error information, and the positional deviation amount of each divided area is corrected. And a step of sequentially transferring the pattern of the mask to the plurality of divided areas while correcting the non-linear component.

According to this, the non-linear component of the positional deviation amount of each divided area and the information of the specific type of transfer error for each row or each column are obtained, and the non-linear component of the positional deviation amount and the information of the transfer error are taken into consideration. Then, the mask pattern is sequentially transferred to each divided area. Therefore, for example, when a mask pattern is superimposed and transferred to each divided area, a specific type of transfer error relating to the divided area differs for each row or column of the matrix, and the deviation amount of the center position of each divided area also differs. However, it is possible to further reduce the residual error as compared with the conventional technique, and as a result, it is possible to transfer the pattern by superimposing the pattern on each divided region with high accuracy. Further, since the information of the specific type of transfer error and the non-linear component of the positional deviation amount obtained for n substrates from the beginning of the lot is used for all the substrates in the lot, the information of the specific type of transfer error is used. Also, the non-linear component of the positional deviation amount can be obtained with high accuracy, and the throughput can be improved.

In each of the exposure methods described in claims 1, 4, 9 and 11, as in the exposure method described in claim 12,
The information of the specific type of transfer error regarding the divided area for each row or each column of the matrix may be obtained by an external measuring device.

In each of the exposure methods according to any one of claims 1 to 12, various kinds of transfer errors of the specific type are conceivable, but as in the exposure method according to claim 13, The specific type of transfer error may include at least one of an orthogonality error and a rotation error of the coordinate axes of the partitioned area.

The invention described in Item 14 is a device manufacturing method including a lithography process, wherein the exposure method according to any one of Items 1 to 13 is used in the lithography process. It is a device manufacturing method.

According to this, in the lithography process, highly accurate exposure is performed by each of the exposure methods described in claims 1 to 13, and the productivity (including yield) of highly integrated devices is improved. Is possible.

[0039]

BEST MODE FOR CARRYING OUT THE INVENTION << First Embodiment >> A first embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a schematic structure of an exposure apparatus 100 suitable for carrying out the exposure method according to the present invention. The exposure apparatus 100 is a step-and-scan type scanning projection exposure apparatus, that is, a so-called scanning stepper.

This exposure apparatus 100 includes a reticle stage R holding an illumination system IOP and a reticle R as a mask.
ST, reticle stage drive system 29 for driving reticle stage RST, projection optical system PL for projecting the image of the pattern formed on reticle R onto wafer W as a substrate coated with a photosensitive agent (photoresist), wafer W And a wafer stage drive system 22 for driving the XY stage 20, a control system for these, and the like. This control system is mainly composed of a main control device 28 that integrally controls the entire device.

The illumination system IOP includes a light source including a KrF excimer laser, an ArF excimer laser, and the like, and an illuminance uniformizing optical system including an optical integrator (a fly-eye lens, an internal reflection type integrator, a diffractive optical element, or the like), an illumination visual field. The illumination optical system includes a reticle blind as a diaphragm, a relay lens system, a condenser lens system and the like (all not shown).

According to the illumination system IOP, illumination light as exposure light generated by the light source (hereinafter referred to as "illumination light IL")
Is converted into a light flux having a substantially uniform illuminance distribution by the illuminance uniformizing optical system. The illumination light IL emitted from the illuminance uniformizing optical system reaches the reticle blind via the relay lens system. The light flux that has passed through the opening of the reticle blind passes through the relay lens system and the condenser lens system to illuminate the slit-shaped illumination area IAR on the reticle R held on the reticle stage RST with a uniform illuminance distribution.

The reticle stage RST has an illumination system I.
It is located below the OP in FIG. The reticle R is suction-held on the reticle stage RST via a vacuum chuck (not shown) or the like. Reticle stage RST has a Y-axis direction (left and right direction on the paper surface in FIG. 1), an X-axis direction (direction orthogonal to the paper surface in FIG. 1), and θz.
In addition to being capable of being finely driven in a direction (a rotation direction around the Z axis orthogonal to the XY plane), it can be driven at a scanning speed designated in a predetermined scanning direction (here, the Y axis direction).

A movable mirror 15 for reflecting a laser beam from a reticle laser interferometer (hereinafter referred to as "reticle interferometer") 21 is fixed on reticle stage RST, and the position on the moving surface of reticle stage RST is fixed. The reticle interferometer 21 is constantly detected with a resolution of, for example, about 0.5 to 1 nm. Here, in practice, a moving mirror having a reflecting surface orthogonal to the Y-axis direction and a moving mirror having a reflecting surface orthogonal to the X-axis direction are provided on reticle stage RST and correspond to these moving mirrors. Although a reticle Y interferometer and a reticle X interferometer are provided as a moving mirror 15 and a reticle interferometer 21 in FIG. Note that, for example, the reticle stage RST
It is also possible to form a reflection surface (corresponding to the reflection surface of the movable mirror 15) by mirror-finishing the end surface of the. Here, one of the reticle Y interferometer and the reticle X interferometer, for example, the reticle Y interferometer is a biaxial interferometer having two length measuring axes, and the reticle stage RST of the reticle stage RST is based on the measurement value of the reticle Y interferometer. In addition to the Y position, the rotation in the θz direction can be measured.

The position information of the reticle stage RST from the reticle interferometer 21 is sent to the main controller 28, and the main controller 28 sends the reticle stage drive system 29 through the reticle stage drive system 29 based on the position information of the reticle stage RST. Drive RST.

As an example of the reticle R, a pattern region is formed in the central portion of a glass substrate as a substantially square mask substrate, and the pattern region is formed on both sides of the pattern region in the X-axis direction.
At least one pair of reticle alignment marks (both not shown) are formed.

The projection optical system PL is arranged below the reticle stage RST in FIG. 1 so that its optical axis AXp is in the Z-axis direction orthogonal to the XY plane. This projection optical system PL is a bilateral telecentric reduction system here, and has a common optical axis A in the Z-axis direction.
A refracting optical system including a plurality of lens elements having Xp is used. The projection magnification of this projection optical system PL is, for example, 1/4, 1/5, 1/6 or the like. Further, a specific plurality of the lens elements can be finely moved, and their movement is controlled by an imaging characteristic correction controller (not shown) on the basis of a command from the main controller 28, so that the projection optical system PL can be controlled. Imaging characteristics (part of optical characteristics), such as magnification, distortion, coma,
Also, the field curvature and the like can be adjusted. Further, the image formation characteristic correction controller adjusts a control parameter (such as applied voltage) of the light source to shift the wavelength of the exposure light IL oscillated from the light source within a predetermined range, thereby forming the image formation characteristic of the projection optical system PL. Can be adjusted.

The XY stage 20 is a Y stage which actually moves in the Y-axis direction on a base (not shown), and the Y stage.
Although it is composed of an X stage which moves on the stage in the X axis direction, these are shown as an XY stage 20 in FIG. 1. The wafer table 18 is mounted on the XY stage 20, and the wafer W is held on the wafer table 18 by vacuum suction or the like via a wafer holder (not shown).

The XY stage 20 moves not only in the scanning direction (Y-axis direction) but also positions a plurality of shot areas on the wafer W in a projection area within the field of view of the projection optical system PL which is conjugate with the illumination area. Therefore, it is configured to be movable also in a non-scanning direction (X-axis direction) orthogonal to the scanning direction. Then, a step-and-scan operation is repeated in which the operation of scanning (scanning) each shot area on the wafer W and the operation of moving to the scanning start position (acceleration start position) for the exposure of the next shot are repeated.

The wafer table 18 is for finely driving the wafer holder that holds the wafer W in the Z-axis direction and in the inclination direction with respect to the XY plane. This wafer table 1
A movable mirror 24 is provided on the upper surface of 8, and a laser beam is projected onto the movable mirror 24 and the reflected light is received to measure the position of the wafer table 18 in the XY plane. A total of 26 is provided so as to face the reflecting surface of the moving mirror 24. Actually, the movable mirror is provided with an X movable mirror having a reflective surface orthogonal to the X axis and a Y movable mirror having a reflective surface orthogonal to the Y axis. Correspondingly, the laser interferometer also has an X movable mirror. An X laser interferometer for directional position measurement and a Y laser interferometer for Y direction position measurement are provided.
In FIG. 1, these are representative of the moving mirror 24 and the laser interferometer 2.
It is shown as 6. Note that, for example, the end surface of the wafer table 18 may be mirror-finished to form a reflection surface (corresponding to the reflection surface of the movable mirror 24). Further, the X laser interferometer and the Y laser interferometer are multi-axis interferometers having a plurality of length measuring axes, and rotate (yaw (θz rotation around Z axis)) in addition to the X and Y positions of the wafer table 18. , Pitching (θx rotation around the X axis) and rolling (θy rotation around the Y axis) are also measurable. Therefore, in the following description, it is assumed that the laser interferometer 26 measures the position of the wafer table 18 in the five-degree-of-freedom directions of X, Y, θz, θy, and θx. The coordinate system (X, Y) composed of the X coordinate and the Y coordinate measured in this way is also referred to as a stage coordinate system below.

The measurement value of the laser interferometer 26 is the main controller 2
8 to the main controller 28, the laser interferometer 26
The position control of the wafer table 18 is performed by driving the XY stage 20 via the wafer stage drive system 22 while monitoring the measurement value of 1.

Further, on the wafer table 18, a reference plate FP whose surface is at the same height as the surface of the wafer W is provided.
Is fixed. On the surface of the reference plate FP, various reference marks including reference marks used for so-called baseline measurement of an alignment detection system described later are formed.

On the side surface of the lens barrel of the projection optical system PL,
An off-axis type alignment detection system AS is attached. As this alignment detection system AS,
For example, by illuminating with a light having a wide wavelength band using a halogen lamp or the like as a light source, image data of the alignment mark (or the reference mark on the reference plate FP) on the wafer W imaged by a CCD camera or the like is image-processed and the mark is obtained. Off-axis of FIA (Field Image Alignment) system for measuring position
An alignment sensor is used.

The alignment control device 16 A / D-converts the information DS from the alignment detection system AS and detects the mark position by referring to the measurement value of the laser interferometer 26. The detection result is supplied from the alignment controller 16 to the main controller 28.

Further, in the exposure apparatus 100 of the present embodiment, although not shown, a reticle is provided above the reticle R via a projection optical system PL disclosed in, for example, Japanese Patent Laid-Open No. 7-176468. A pair of reticles composed of a TTR (Through The Reticle) alignment system using an exposure wavelength for simultaneously observing a reticle mark on R or a reference mark (both not shown) on reticle stage RST and a mark on reference plate FP at the same time. An alignment microscope is provided. The detection signals of these reticle alignment microscopes are supplied to main controller 28 via alignment controller 16.

The main controller 28 includes a CPU (central processing unit), a ROM (read only memory), and a RAM.
(Random access memory), a so-called microcomputer (or workstation) including various interfaces including a communication interface, etc. is included, so that the exposure operation can be performed accurately, for example,
Synchronous scanning of the reticle R and the wafer W, stepping of the wafer W, exposure timing, and the like are collectively controlled. Further, the main controller 28 is connected to the storage device 27 so that various data can be stored in and read from the storage device 27.

Next, the exposure processing operation of the exposure apparatus 100 configured as described above will be described with reference to the flowchart of FIG. The flowchart of FIG. 2 shows a processing algorithm of the main controller 28.

Here, as an example, the pattern of the second layer is transferred onto one lot of wafers W _k (for example, k = 1 to 25). As a prerequisite, each wafer W k is transferred.
It is assumed that a plurality of shot areas to which the pattern of the first layer including the alignment mark is transferred are already formed on _k by using another exposure apparatus (scanning stepper). In the present embodiment, it is assumed that, as the alignment marks, four two-dimensional marks whose positions in the X-axis direction and the Y-axis direction can be simultaneously detected are formed in four shot regions.

Further, each shot area is arranged in a matrix of Cy in the Y-axis direction (scanning direction) and Cx in the X-axis direction (non-scanning direction). In this embodiment, the scanning direction is called the row direction and the non-scanning direction is called the column direction.

In step 401 of FIG. 2, the reticle R designated on the reticle stage RST is loaded using a reticle loader (not shown). Here, as an example,
It is assumed that the reticle R has a pattern for the second layer.

In step 403, a counter k indicating the number of the loaded wafer from the beginning of the lot is set to 1, and the wafer W ₁ at the beginning of the lot is placed on the wafer table 18 using a wafer loader (not shown). To load.

In step 405, for example, at least a pair of reticle alignment marks and at least a pair of reference marks formed on the surface of the reference plate FP corresponding to the reticle alignment marks are projected by the reticle alignment microscope through the projection optical system PL. Detects the relative position of. Then, based on the measured values of the reticle interferometer 21 and the laser interferometer 26 at that time, the reticle stage coordinate system defined by the length measurement axis of the reticle interferometer 21 and the length measurement axis of the laser interferometer 26 are defined. Obtain the relationship with the wafer stage coordinate system. That is, reticle alignment is performed in this manner.

In step 407, first, the wafer stage drive system 22 is monitored while monitoring the measurement value of the laser interferometer 26.
The XY stage 20 is moved by a predetermined baseline value (design value) via the, and the reference plate FP is positioned immediately below the alignment detection system AS. Then, the alignment detection system AS is used to detect the reference mark (not shown) for baseline measurement formed on the surface of the reference plate FP. Further, based on each detection result of the reticle alignment microscope, the detection result of the alignment detection system AS, and the measurement value of the laser interferometer 26 at each detection, the baseline value of the alignment detection system AS, that is, the reticle. The positional relationship (baseline value) between the projected position of the pattern and the detection center of the alignment detection system AS is calculated.

In step 409, the wafer stage drive system 22 is operated based on the designed array coordinates of each shot area.
Alignment detection system AS for all shot areas via
Positions of all the alignment marks formed in each shot area are detected with the detection center of the alignment detection system AS as a reference while sequentially locating immediately below.

In step 410, the above-described multi-point shot EGA calculation is performed on the basis of the detected position information of each alignment mark, and 10 error parameters, that is, scaling of the wafer W _{k in} the X and Y directions (wafer W _k
Linear expansion and contraction of) the rotation error of the wafer W _k, X of the wafer W _k, Y direction offset, the stage coordinate system orthogonality error of, X in the shot area, linear expansion and contraction of the Y-direction scaling (shot area), the shot area The rotation error and the orthogonality error of the shot area are calculated. And the required 10
The array coordinates of each shot area are calculated from the individual error parameters, the design position information of the reference point in each shot area, and the design relative position information of the alignment mark with respect to the reference point. Array coordinates of the calculated shot area where the linear expansion and contraction of the wafer W _k, the rotation error of the wafer W _k, X of the wafer W _k, Y direction offset, orthogonality error of the stage coordinate system is considered. Further, the non-linear component of the positional deviation amount of each shot area is obtained from the position information of the alignment mark belonging to each shot area and the array coordinates of each shot area obtained by the multi-point shot EGA. Then, a correction value for the non-linear component of the displacement amount is obtained for each shot area, and is stored as displacement information in the storage device 2.
Store in 7. Further, out of the 10 error parameters obtained here, 8 error parameters (wafer W _k
Linear expansion and contraction, rotation error of the wafer _{W k,} X of the wafer _{W k,}
The offset in the Y direction, the orthogonality error of the stage coordinate system, and the linear expansion / contraction of the shot area are stored in the storage device 27 as wafer error information (information of transfer error other than a specific type).

In step 411, the counter i indicating the row number of the shot area is set to 1 to set the target shot area to the first row.

In step 413, at least four alignment marks are selected from at least three shot areas in the i-th row, and the in-shot multipoint EGA calculation is performed based on the position information of each selected alignment mark, eight error parameters, i.e. linear expansion and contraction of the wafer _{W k,} the rotation error of the wafer _{W k,} X of the wafer _{W k,} Y
A direction offset, a stage coordinate system orthogonality error, a shot area rotation error, and a shot area orthogonality error are obtained. Of the error parameters obtained here, information on the rotation error and the orthogonality error of the shot area is stored in the storage device 27 as shot error information (information of a specific type of transfer error) on the shot area of the i-th row. .

In step 415, the counter i is referred to, and the multi-point E in the shot is set for the shot areas of all the rows.
It is determined whether or not the GA calculation has been performed. Here, i =
Since the in-shot multipoint EGA calculation is only performed for the shot area of 1, ie, the first row, step 4
The determination at 15 is denied, and the process proceeds to step 417.

In step 417, the value of the counter i is incremented (+1) to make the shot area of the next row the target shot area, and the process returns to step 413.

Thereafter, the processing / judgment of steps 413 → 415 → 417 is repeated until the judgment of step 415 is affirmed.

When the intra-shot multipoint EGA calculation for the shot areas of all rows is completed, the value of the counter i is Cy.
Then, the determination in step 415 is affirmed, and the process proceeds to step 421.

In step 421, the counter i indicating the row number of the shot area is set to 1 and the shot area in the first row is set as the exposure target area.

At step 423, 1 is set to the counter j indicating the column number of the shot area, and the shot area in the first column is set as the exposure target area. That is, the shot area arranged in the first row and the first column becomes the exposure target area.

At step 425, the imaging magnification correction controller (not shown) of the projection optical system PL is controlled in consideration of the linear expansion / contraction of the shot area in the non-scanning direction included in the wafer error information, and the projection magnification of the projection optical system PL is adjusted. adjust. Further, the array coordinates of the exposure target area are corrected based on the positional deviation information of the exposure target area. Then, based on the corrected array coordinates, the XY stage 2 is set so that the position of the wafer W _k becomes the acceleration start position for exposing the exposure target region.
While moving 0, the reticle stage RST is moved so that the position of the reticle R becomes the acceleration start position.

In step 427, the reticle stage R
Relative scanning between the ST and XY stage 20 is started. When both stages reach their respective target scanning velocities and reach the constant velocity synchronous state, the pattern area of the reticle R starts to be illuminated by the illumination light IL from the illumination system IOP, and scanning exposure is started. The relative scanning is performed by monitoring the measurement values of the laser interferometer 26 and the reticle interferometer 21 and driving the wafer stage drive system 22 and the reticle stage drive while considering the wafer error information and the shot error information of the shot area of the i-th row. This is done by controlling the system 29. That is, in consideration of the linear expansion and contraction of the shot area in the scanning direction included in the wafer error information, reticle stage RST
Relative to the scanning speed of the XY stage 20 is adjusted, and the relative scanning axis direction between the reticle R and the wafer W is adjusted in consideration of the orthogonality error of the shot area in the i-th row. In addition, in consideration of the rotation error of the shot area of the i-th row, XY is set for the reticle stage RST.
The stage 20 is rotated in advance to perform relative scanning. Then, the areas of the reticle R having different pattern areas are illuminated by the illumination light I.
Sequential illumination is performed with L, and the scanning exposure is completed when the illumination of the entire pattern area is completed. Thus, the rotation error of the shot areas, perpendicularity error of the shot regions, the linear expansion and contraction of the shot area, linear expansion or contraction of the wafer W _k, the rotation error of the wafer W _k, X of the wafer W _k, Y direction offset, the stage coordinate system Error in the orthogonality and the non-linear component of the positional deviation amount are corrected, and the pattern of the reticle R is projected onto the projection optical system P.
It is reduced and transferred to the exposure target region on the wafer W _k via L.

In step 429, the counter j is referred to, and it is determined whether or not exposure has been performed on all shot areas in the i-th row. Here, j = 1, that is, only the shot area in the first column has been exposed. Therefore, the determination at step 429 is denied and step 43 is performed.
Move to 1.

In step 431, the value of the counter j is incremented (+1) to set the shot area in the next column in the same row as the exposure target area, and the process returns to step 425.

Thereafter, the processing / judgment of steps 425.fwdarw.427.fwdarw.429.fwdarw.431 is repeated until the judgment of step 429 is affirmed. As a result, the pattern is sequentially transferred to each shot area in the i-th row.

When the transfer of the pattern to all the shot areas in the i-th row on the wafer W _k is completed, the value of the counter j becomes Cx, the determination at step 429 is affirmative, and the routine goes to step 433.

In step 433, the counter i is referred to, and it is determined whether or not the patterns have been transferred to the shot areas of all the rows. Here, i = 1, that is,
Since only the pattern has been transferred to the shot area of the first row, the determination at step 433 is denied and the routine proceeds to step 435.

In step 435, the value of the counter i is incremented (+1) to set the shot area of the next row as the exposure target area, and the process returns to step 423.

Thereafter, the processing / judgment from step 423 to step 435 is repeated until the judgment in step 433 is affirmed.

When the transfer of the patterns to the shot areas of all the rows on the wafer W _k is completed, the value of the counter i becomes Cy.
Then, the determination in step 433 is affirmed, and the process proceeds to step 437.

In step 437, the wafer loader (not shown) is instructed to unload the wafer W _k . This allows
Wafer W _k, due loader not shown, after being unloaded from above the wafer table 18 by the wafer transport system (not shown), is transported to the coater-developer (not shown) which is connected in-line in the exposure apparatus 100 It

In step 439, the value of the counter k is referred to, and it is determined whether or not the transfer of the pattern to all the wafers in the lot is completed. Here, k = 1, that is, only the first wafer W ₁ has been transferred, so the determination in step 439 is denied, and the process proceeds to step 441.

In step 441, the value of the counter k is incremented (+1) and the next wafer W _k is loaded on the wafer table 18 by using a wafer loader (not shown).

In step 443, the value of the counter k is referred to, and it is determined whether the loaded wafer W _k exceeds the nth wafer in the lot (fifth wafer in this embodiment, for example). Here, since k = 2, that is, the second wafer W ₂ is loaded, the determination in step 443 is denied, and the process returns to step 409.

Thereafter, the processing / judgment from step 409 to step 443 is repeated until the judgment in step 443 is affirmed.

When the transfer of the pattern from the head of the lot to the nth wafer W _n is completed, the value of the counter k at step 443 is n + 1, the determination at step 443 is affirmative, and the routine proceeds to step 445. .

In step 445, the value of the counter k is referred to, and it is determined whether the loaded wafer W _k is the n + 1th wafer in the lot. The value of the counter k here is n +
1, that is, since the n + 1th wafer W _{n + 1} in the lot is loaded, the determination in step 445 is positive,
Control goes to step 447.

In step 447, the positional deviation information and the shot error information of each wafer (n wafers) stored in the storage device 27 are read out and statistically calculated (for example, averaged) to newly generate the positional deviation information and the positional deviation information. It is stored in the storage device 27 as shot error information.

In step 449, position information of five or more alignment marks selected from three or more shot regions of all shot regions is detected, and based on the position information, multi-point EGA calculation in shot is performed. I do. Then, the array coordinates of each shot area are calculated from the obtained ten error parameters, the design position information of the reference point in each shot area, and the design relative position information of the alignment mark with respect to the reference point. . In addition, among the error parameters obtained here, the linear expansion and contraction of the wafer W _k ,
Rotational error of the wafer W _k, the wafer W _k X, Y direction offset, the stage coordinate system orthogonality error of linear expansion of the shot area is stored as the wafer error information in the storage device 27. Then, the process returns to step 421.

Hereinafter, steps 421 to 445.
Perform processing and judgment up to.

Next, at step 445, since the value of the counter k is n + 2, the determination at step 445 is denied and the routine proceeds to step 449. Then, until the determination in step 439 is affirmative, step 421
The processes and judgments from to step 449 are repeated.

When the transfer of the pattern to all the wafers W _k of the lot is completed, the determination in step 439 is affirmed and the process is completed.

As described above, according to the first embodiment, the exposure apparatus 100 is used for a plurality of shot areas formed in a matrix arrangement on the wafer W _k by using another exposure apparatus. in transferring by overlapping reticle pattern, it obtains the positional information of the alignment marks formed in each shot area on the wafer W _k, based on the position information, the shot error information on each shot area on each row of the matrix Looking for. The shot error information is used to correct the rotation error of the shot area and the orthogonality error of the shot area for each row of the matrix, and the patterns are sequentially transferred to each shot area. It is possible to reduce the residual error caused by the difference in the exposure apparatus used for exposing the layer to be exposed, as compared with the related art, and as a result, it is possible to transfer the pattern by superimposing it on each shot region with high accuracy.

Here, the residual error caused by the difference in the exposure apparatus will be specifically described. For example, a length-measuring system used for measuring the position of a wafer, which is provided in an exposure apparatus (scanning stepper) that exposes layers to be superimposed, includes a multi-axis interferometer having a plurality of length-measuring axes. And an X-reflecting mirror (X-reflecting mirror having a reflecting surface orthogonal to the X-axis
The yawing of the wafer W during scanning exposure (rotation about the Z axis by θz rotation) by the laser light reflected by the moving mirror).
Is measured, and yawing of the wafer W is corrected based on the measurement result. When the X-moving mirror has a mirror bend, an erroneous correction is made in an attempt to correct the yawing of the wafer W during scanning exposure, and a rotation error occurs in each shot area. In this case, as shown in FIG. 3 as an example, when the shot areas arranged in the same row are compared, the rotation errors of the shot areas are almost the same, but when the shot areas arranged in different rows are compared, the shot areas are shot. The rotation error of the area may be different.

This is similar to the case of the orthogonality error of the shot areas described above. In each shot area arranged in the same row, the influence of mirror bending on the transfer error is almost the same, but the shot areas are arranged in different rows. This is because the influence of the mirror bending on the transfer error is not necessarily the same in the shot area.

According to the first embodiment, the information of the rotation error and the orthogonality error of the shot area is obtained for each row of the matrix, and the transfer is performed in consideration of the information. In the exposure apparatus that exposes the layer to be exposed, the residual error can be reduced and the overlay accuracy can be improved as a result even if the above-mentioned mirror bending of the X moving mirror exists.

Further, the position of the reference point in the shot area may be affected by the bending of the mirror of the movable mirror or the effect of the process. According to the first embodiment, the in-shot multipoint EGA calculation is performed on all shot regions as the measurement target, and the positional deviation information regarding each shot region is obtained for each shot region based on the result. At the time of transfer, the positional deviation of the reference point of the shot area is corrected in consideration of the positional deviation information of the shot area to be transferred. Thereby, the overlay accuracy can be further improved.

Further, according to the first embodiment, the wafer
W_kAlignment mark formed on each shot area above
Each system calculated by statistical calculation based on the position information of the
The array coordinates of the hot region are the wafer W._kLinear expansion and contraction
Ha W_kRotation error, wafer W _kX, Y direction offset
Because the orthogonality error of the stage and stage coordinate system is taken into consideration,
Reducing overlay error due to these errors
You can Furthermore, before transferring, each shot area
Of the projection optical system P based on linear expansion and contraction in the non-scanning direction of
Adjust the projection magnification of L and run each shot area.
Reticle stage R based on linear expansion and contraction in the scanning direction
The relative speed between ST and XY stage 20 is adjusted.
Error due to magnification error in the shot area.
The difference can be reduced.

Furthermore, according to the first embodiment, the shot error information is obtained for each row of the matrix by statistical calculation using the position information of the alignment mark selected from the shot areas belonging to the same row. Therefore, as compared with the case where the shot error information is obtained for each shot area, the shot error information can be obtained with high accuracy without lowering the throughput.

Further, according to the first embodiment, the lot
Each wafer W from the beginning to the nth wafer _kAbout
Position information based on the position information of the
Shot error information is calculated, but lot of n + 1
Wafer W after the eyes_kFor the
From the beginning of the lot without calculating the calculation error information.
Each wafer W up to nth wafer_kMisalignment calculated in
Information and shot error information obtained by statistical calculation processing
The positional deviation information and the shot error information are used. this
Allows for superimposing without reducing throughput
The accuracy can be improved.

In the first embodiment, the positional deviation information and the shot error information are calculated for each wafer W _k from the beginning of the lot to the n-th wafer in advance, and the statistical calculation processing is performed on each information. And newly obtain the positional deviation information and shot error information in the lot. Then, when the wafers W _k in the lot are exposed next, the positional deviation information and the shot error information in the lot may be used for all the wafers W _k in the lot.

Further, in the first embodiment, the positional deviation information and the shot error information are calculated based on the positional information of the alignment marks for each wafer W _k from the head of the lot to the n-th wafer. Not limited to this,
For example, the positional deviation information and the shot error information may be calculated only for the _first wafer W _{1 in the} lot, and those values may be used for the subsequent wafers W _k . Thereby, the throughput can be further improved. Of course, for all of the wafer W _k, it may calculate the position displacement information and the shot error information.

In the first embodiment, when it is not necessary to consider the non-linear component of the positional deviation in each shot area, the positional deviation amount of each shot area is not detected (step 410 in FIG. 2). May be. However, in this case, for each wafer W _k from the head of the lot to the nth wafer W _k , in order to obtain the information on the array coordinates of each shot area and the wafer error, step 449 in FIG.
The same processing is performed.

In the first embodiment, the position information of all alignment marks belonging to all shot areas on the wafer Wk is _obtained in step 409 of FIG. Detection of quantity (Fig. 2
If the step 410) of step 1) is unnecessary, the present invention is not limited to this, and the position information about at least four (in the case of a two-dimensional mark) alignment marks selected from at least three shot areas for each row. Should be obtained.

Further, in the first embodiment described above, the case where the step-and-scan type exposure apparatus 100 is used when exposing the second layer has been described. However, the step-and-repeat type exposure apparatus is used. May be used. However, in this case, since the exposure (collective exposure) is performed with both the reticle and the wafer stationary, it is not possible to perform a strict correction for the orthogonality error of the shot area. However, by rotating the reticle (reticle stage), it is possible to reduce the overlay error due to the orthogonality error of the shot area to some extent. Therefore, in this case, when the second layer is exposed, the reticle stage is controlled so that the error, which is the sum of the rotation error of the shot area and the orthogonality error, is minimized.

In the first embodiment, the shot is
Positional deviation information and shot error information by multi-point EGA calculation
It is seeking information, but is not limited to this. An example
For example, a lot of wafers W_kSame as the first layer pattern
The exposure apparatus 1 is placed on the test wafer on which the
00 is used to transfer the pattern of the second layer, not shown
Using an external measuring device such as an overlay measuring device, the first layer
Registration error between eye pattern and second layer pattern
Position error and position information based on the measurement result.
You may ask for error information. And in this way
Storage device for position deviation information and shot error information obtained by
The wafer W of the lot is stored in 27. _kSecond layer on top
Position information and shot error information when exposing
The data is read from the storage device 27 and transferred in consideration of this information.
It is possible to improve the overlay accuracy by taking a copy.
You can

Further, in the above-described first embodiment, when the pattern of the second layer is superposed on the pattern of the first layer transferred by using another exposure apparatus, the pattern of the second layer is transferred by using the exposure apparatus 100. However, the present invention is not limited to this. For example, when the pattern of the fourth layer is transferred using the exposure apparatus 100 onto the wafer _Wk onto which the patterns of the first layer to the third layer have already been transferred using a plurality of other exposure apparatuses. , May be matched with the pattern of the second layer. In short, one of the layers up to the front layer may be used as the reference layer when superposed. Ultimately, the result of overlaying all layers is important.

<< Second Embodiment >> The second embodiment of the present invention will be described below with reference to the flowchart of FIG. 4 focusing on the differences from the first embodiment. The flowchart of FIG. 4 shows a processing algorithm of the main controller 28. Here, one lot of wafers W _k (for example, k = 1
25), the pattern of the second layer is formed on the exposure apparatus 10 described above.
0 is used for the transfer, and the preconditions are the same as those in the first embodiment.

Further, in the second embodiment, a plurality of (for example, M, M) used for exposing different layers on the wafer W _k in advance.
Position exposure information and shot error information regarding the shot area for each exposure device, the storage device 2
7 is stored.

That is, by individually using each exposure apparatus,
Test the reticle pattern that includes a fixed alignment mark
Wafer Wt_m(M = 1, 2, ..., M)
Transfer each wafer Wt_mForm multiple shot areas on top
To do. Then, each wafer Wt _mAfter developing
Transfer to the overlay measurement device (external measurement device) and overlay
Wafer Wt_mAlignment
Position for each shot area based on position information
The shift information and the shot error information are obtained. Exposure apparatus 10
At 0, the main controller 28 is positioned from the overlay measuring device.
The shift information and the shot error information are provided to, for example, a net (not shown).
It is received via the network and stored in the storage device 27.

In step 501 of FIG. 4, the reticle R designated on the reticle stage RST is loaded using a reticle loader (not shown).

In steps 503 and 505, the same processing as steps 405 and 407 in the first embodiment is performed.

At step 507, the counter k indicating the number of the loaded wafer from the top of the lot is set to 1
Is set, and the _first wafer W ₁ of the lot is loaded on the wafer table 18 by using a wafer loader (not shown).

In step 509, the positional deviation information and the shot error information regarding the shot area in the specific exposure apparatus which has exposed the layer (reference layer) to be superposed among the layers up to the previous layer are stored from the storage device 27. read out.

At step 511, the same processing as step 449 in the first embodiment is performed.

In steps 513 to 529, the same processing as steps 421 to 437 in the first embodiment is performed.

At step 531, the value of the counter k is referred to, and it is determined whether or not the transfer of the pattern to all the wafers in the lot is completed. Here, k = 1, that is, only the first wafer W ₁ has been transferred, so the determination at step 531 is negative, and the process proceeds to step 533.

In step 533, the value of the counter k is incremented (+1), and the next wafer W _k is loaded on the wafer table 18 by using a wafer loader (not shown). Then, the process returns to step 511.

Thereafter, the processing / judgment from step 511 to step 533 is repeated until the judgment in step 531 is affirmed.

When the transfer of the pattern to all the wafers W _k of the lot is completed, the determination at step 531 is affirmed and the process is completed.

As described above, according to the second embodiment, the positional deviation information and the shot error information regarding the shot area for each exposure apparatus are previously set for a plurality of exposure apparatuses used to expose different layers on the wafer. Is acquired and stored in the storage device 27. Then, when the reticle patterns are superposed and transferred by the exposure apparatus 100 onto a plurality of shot areas formed in a matrix arrangement on the wafer W _k , the reference layer to be superposed is exposed. The positional deviation information and the shot error information of a specific exposure apparatus are read from the storage device 27, and the reticle pattern is sequentially transferred to each shot area in consideration of them, so that the residual error due to the difference of the exposure apparatus is eliminated. As a result, it is possible to reduce the number of patterns, and as a result, it is possible to improve the pattern overlay accuracy without reducing the throughput.

Further, in the second embodiment, the positional deviation information and the shot error information are obtained for each exposure apparatus used for exposing different layers on the wafer W _k . However, the exposure apparatus having a twin stage is used. In the case of, the positional deviation information and the shot error information are further obtained for each stage.

In the second embodiment, the wafer W
_The positional deviation information and the shot error information are obtained for each exposure apparatus used for exposing different layers on _k . However, if it is not necessary to consider the nonlinear component of the positional deviation in each shot area, the positional deviation information is obtained. You don't have to.

Further, in the above first and second embodiments, the case where the specific exposure apparatus that exposed the reference layer to be superposed is the step-and-scan type exposure apparatus has been described. -And-repeat type exposure apparatus may be used. However, in this case, exposure (batch exposure) is performed with both the reticle and the wafer stationary.

<< Third Embodiment >> The third embodiment of the present invention will be described below with reference to the flowchart of FIG. 5 focusing on the differences from the first and second embodiments. The flowchart of FIG. 5 shows a processing algorithm of the main controller 28.

Here, as an example, the exposure apparatus 100 is used to transfer the pattern of the first layer onto one lot of wafers W _k (eg, k = 1 to 25), and the second and subsequent layers are transferred. The case where the pattern is transferred to be superimposed on the pattern of the first layer by using the exposure apparatus will be described. In addition, Cy-shaped virtual areas in the Y direction (row direction) and Cx in the X direction (column direction) are set on the wafer W _k , and the reticle pattern is transferred using the virtual areas as target areas. To do.

Further, in the third embodiment, similar to the second embodiment, the positions of the shot areas of the exposure apparatuses are set in advance for a plurality of exposure apparatuses used for exposing different layers on the wafer W _k. It is assumed that the shift information and the shot error information are stored in the storage device 27.

At step 601, the reticle R designated on the reticle stage RST is loaded using a reticle loader (not shown).

In steps 603 and 605, the same processing as steps 405 and 407 in the first embodiment is performed.

At step 607, the counter k indicating the number of the loaded wafer from the top of the lot is set to 1
Is set, and the _first wafer W ₁ of the lot is loaded on the wafer table 18 by using a wafer loader (not shown).

In step 609, positional deviation information and shot error information regarding a shot area in a specific exposure apparatus which performs overlay exposure using the pattern of the first layer as a reference layer among the second and subsequent layers are stored. Device 27
Read from.

In step 611, the counter i indicating the line number of the target area is set to 1 and the target area on the first row is set as the exposure target area.

At step 613, the counter j indicating the column number of the target area is set to 1 and the target area on the first column is set as the exposure target area. That is, the target area set in the first row and the first column becomes the exposure target area.

In step 615, the array coordinates of the exposure target area are corrected based on the positional deviation information in the specific exposure apparatus. Then, based on the corrected array coordinates, the XY stage 20 is moved so that the position of the wafer W _k becomes the acceleration start position for exposing the exposure target region, and the position of the reticle R becomes the acceleration start position. To move reticle stage RST.

At step 617, the reticle stage R
Relative scanning between the ST and XY stage 20 is started. And
Both stages reach their target scan speeds and synchronize at a constant speed
When the state is reached, the illumination light IL from the illumination system IOP causes
The pattern area of the reticle R begins to be illuminated and scanning exposure is performed.
Is started. The above relative scanning is performed by the laser interferometer 26 and
And the measurement value of the reticle interferometer 21 are monitored,
Shot error in shot area of i-th row in exposure apparatus
Wafer stage drive system 22 and reticle considering information
This is performed by controlling the stage drive system 29. You
That is, the shot area of the i-th row in the specific exposure apparatus
Of the reticle R and the wafer W considering the orthogonality error of
Adjusting the scanning axis direction relative to a specific exposure device
Considering the rotation error of the shot area of the i-th row in
Forecast the XY stage 20 against the reticle stage RST
Rotation to perform relative scanning. And of Reticle R
Areas having different pattern areas are sequentially illuminated with the illumination light IL.
The illumination of the entire pattern area is completed.
Scanning exposure is completed. This allows for specific exposure equipment
Rotation error of shot area, orthogonality of shot area
The reticle R
Wafer W through the projection optical system PL _kDew on
The image is reduced and transferred to the light target area.

In step 619, the counter j is referred to, and it is determined whether or not the exposure has been performed on all the target areas in the i-th row. Here, j = 1, that is, only the target area in the first column has been exposed. Therefore, the determination at step 619 is negative, and the process proceeds to step 621.

At step 621, the value of the counter j is incremented (+1) to set the target area of the next column in the same row as the exposure target area, and the process returns to step 615.

Thereafter, the processing / judgment of steps 615 → 617 → 619 → 621 is repeated until the judgment of step 619 is affirmed.

When the transfer of the pattern to all the target areas in the i-th row on the wafer W _k is completed, the value of the counter j is Cx.
Therefore, the determination at step 619 is affirmative, and the process proceeds to step 623.

In step 623, the counter i is referred to, and it is determined whether or not the patterns have been transferred to the target areas of all the rows. In this case, i = 1, that is, only the pattern is transferred to the target area on the first row, so the determination at step 623 is negative, and the routine proceeds to step 625.

In step 625, the value of the counter i is incremented (+1) to set the target area of the next row as the exposure target area, and the process returns to step 613.

Thereafter, the processing / judgment from step 613 to step 625 is repeated until the judgment in step 623 is affirmed.

When the transfer of the pattern to the target areas of all the rows on the wafer W _k is completed, the value of the counter i becomes Cy, and the determination at step 623 is affirmative, and step 62
Move to 7.

At step 627, the wafer loader (not shown) is instructed to unload the wafer W _k . This allows
Wafer W _k, due loader not shown, after being unloaded from above the wafer table 18 by the wafer transport system (not shown), is transported to the coater-developer (not shown) which is connected in-line in the exposure apparatus 100 It

At step 629, it is determined whether or not the transfer of the pattern to all the wafers W _{k of the} lot is completed by referring to the value of the counter k. Here, k = 1, that is, only the first wafer W ₁ has been transferred, so the determination in step 629 is denied, and the process proceeds to step 631.

In step 631, the value of the counter k is incremented (+1) and the next wafer W _k is loaded on the wafer table 18 by using a wafer loader (not shown). Then, the process returns to step 611.

Thereafter, the processing / judgment from step 611 to step 631 is repeated until the judgment in step 629 is affirmed.

When the transfer of the pattern to all the wafers W _k of the lot is completed, the determination in step 629 is affirmed, and the process is completed.

As described above, according to the third embodiment, the positional deviation information and the shot error information regarding the shot area for each exposure apparatus are previously set for a plurality of exposure apparatuses used for exposing different layers on the wafer. Is acquired and stored in the storage device 27. Then, when the reticle pattern is transferred to the matrix-shaped virtual area set on the wafer W _k by using the exposure apparatus 100, the first layer of the layers transferred from the exposure apparatus 100 is selected from the next and subsequent layers. The positional deviation information and the shot error information of a specific exposure apparatus that performs overlay exposure using the pattern as a reference layer are read from the storage device 27, and the patterns are sequentially transferred to each virtual area in consideration of them, so that the specific area is transferred. It is possible to suppress the overlay error when transferring with the exposure device, and consequently improve the overlay accuracy of the patterns.

In the third embodiment, among the layers after the next layer, another specific exposure apparatus for performing overlay exposure using the pattern of the first layer transferred by the exposure apparatus 100 as a reference layer. However, in the case of the step-and-repeat exposure apparatus, the shot error information does not have to include the orthogonality error of the shot area.

In the third embodiment, which layer is to be used as the reference layer for superposition can be designated in advance by the operator via an input device (not shown). If there is no instruction from the operator, main controller 28 automatically selects the exposure apparatus that is expected to have the largest overlay error, and corrects it based on the positional deviation information and shot error information in that exposure apparatus. May be done.

In addition, when the pattern of the previous layer has already been transferred onto the wafer, the first embodiment or the second embodiment
Instead of performing the correction on the previous layer as in the third embodiment, the correction may be performed on the next and subsequent layers as in the third embodiment. Ultimately, the result of overlaying all layers is important. It should be noted that the operator can instruct which of the corrections is to be performed in advance through an input device (not shown).

In each of the above embodiments, when the scanning direction is the row direction and the shot areas in the same row are compared, the rotation error and the orthogonality error in the shot area are almost the same, and the shot areas in different rows are compared. By comparison, the rotation error and the orthogonality error of the shot area may be different, but the shot area is not limited to this. For example, a Y moving mirror having a reflecting surface orthogonal to the Y axis reflects the light. In the length measurement system that detects the yawing of the wafer by the laser beam generated, if the Y moving mirror has a bend in the mirror, erroneous yawing correction is performed. In this case,
The influence of the mirror bending on the rotation error of the shot areas is similar when comparing the shot areas arranged in the same column, but not necessarily the same when comparing the shot areas arranged in different columns. Therefore, in this case, the rotation error of the shot area may be obtained for each column and corrected for each column.

Further, in each of the above-described embodiments, the rotation error and the orthogonality error of the shot area are obtained for each row, but the present invention is not limited to this. For example, the rotation error and the orthogonality error for each row, At least one of the rotation error and the orthogonality error for each column may be obtained. For this, which error should be taken into consideration may be appropriately selected according to the degree of influence of the bending of the mirrors of the X and Y movable mirrors on each of the above errors.

Further, in the second and third embodiments,
The positional deviation information and the shot error information about the other exposure apparatus obtained by the overlay measuring apparatus are received via the network, for example, and are stored in the storage device 27. You may input each information via. Further, it is also possible to use the exposure apparatus 100 to obtain the positional deviation information and shot error information for other exposure apparatuses without using the overlay measurement apparatus.

Further, in the second and third embodiments, as the plurality of exposure apparatuses used for exposing different layers on the wafer, an exposure apparatus for performing wafer alignment based on the measurement value of the reference wafer, and a laser. An exposure apparatus that performs wafer alignment based on the measurement value of the interferometer may coexist. An exposure device for exposing the reference layer,
When the wafer alignment reference is different between the exposure apparatus that performs exposure by superimposing on the reference layer, the correction is performed in consideration of the difference in the wafer alignment reference.

Furthermore, the light source of the exposure apparatus to which the present invention is applied is not limited to the KrF excimer laser or the ArF excimer laser, but may be an F ₂ laser (wavelength 157 nm) or another pulsed laser light source in the vacuum ultraviolet region. good. In addition, for example, erbium (or both erbium and ytterbium) -doped fiber is used as exposure illumination light, for example, a single-wavelength laser light in the infrared region or visible region emitted from a DFB semiconductor laser or a fiber laser. It is also possible to use a harmonic wave that is amplified by an amplifier and converted into ultraviolet light by using a nonlinear optical crystal.

Further, the projection optical system PL may be any of a refraction system, a catadioptric system, and a reflection system, and may be a reduction system, a unit magnification system, and an enlargement system.

Further, the present invention is applicable not only to an exposure apparatus used for manufacturing a semiconductor element, but also for an exposure apparatus for transferring a device pattern onto a glass plate, which is used for manufacturing a display including a liquid crystal display element and a plasma display. Exposure used for manufacturing a thin film magnetic head, such as an exposure device for transferring a device pattern onto a ceramic wafer, an image pickup device (CCD, etc.), a micromachine, a DNA chip, and a mask or reticle. It can also be applied to devices and the like.

<< Device Manufacturing Method >> Next, an embodiment of a device manufacturing method using each of the exposure methods described above will be described.

In FIG. 6, devices (semiconductor chips such as IC and LSI, liquid crystal panel, CCD, thin film magnetic head, D
A flow chart of an example of manufacturing an NA chip, a micromachine, etc. is shown. As shown in FIG. 6, first, in step 301 (design step), device function / performance design (for example, circuit design of a semiconductor device)
And design the pattern to realize the function. Continuing, step 302 (mask making step)
At, a mask on which the designed circuit pattern is formed is manufactured. On the other hand, step 303 (wafer manufacturing step)
In, a wafer is manufactured using a material such as silicon.

Next, in step 304 (wafer processing step), the mask and wafer prepared in steps 301 to 303 are used to form an actual circuit or the like on the wafer by a lithography technique, as will be described later. Next, step 305 (device assembly step)
In step 3, device assembly is performed using the wafer processed in step 304. This step 305 includes processes such as a dicing process, a bonding process, and a packaging process (chip encapsulation) as needed.

Finally, step 306 (inspection step)
In step 3, inspections such as an operation confirmation test and a durability test of the device manufactured in step 305 are performed. After these steps, the device is completed and shipped.

FIG. 7 shows a detailed flow example of step 304 in the case of a semiconductor device. In FIG. 7, in step 311 (oxidation step), the surface of the wafer is oxidized. Step 312
In the (CVD step), an insulating film is formed on the wafer surface. In step 313 (electrode forming step), electrodes are formed on the wafer by vapor deposition. Step 3
In 14 (ion implantation step), ions are implanted in the wafer. Steps 311 to 314 described above
Each of them constitutes a pretreatment process of each stage of wafer processing, and is selected and executed according to the required treatment in each stage.

At each stage of the wafer process, after the above-mentioned pretreatment process is completed, the posttreatment process is executed as follows. In this post-treatment process, first, step 3
In 15 (resist formation step), a photosensitive agent is applied to the wafer. Subsequently, in step 316 (exposure step), the circuit pattern of the mask is transferred onto the wafer by the exposure method of each of the above embodiments. Next, in step 317 (developing step), the exposed wafer is developed, and in step 318 (etching step), exposed members other than the portion where the resist remains are removed by etching. And step 319
In the (resist removing step), the unnecessary resist after etching is removed.

By repeating these pre-processing step and post-processing step, multiple circuit patterns are formed on the wafer.

When the device manufacturing method of this embodiment as described above is used, the exposure method of each of the above-described embodiments is used in the exposure step, so that highly accurate overlay exposure is performed and a highly integrated device is obtained. Can be manufactured with high productivity.

[0172]

As described in detail above, according to the exposure method of the present invention, it is possible to suppress the overlay error that occurs when the different layers on the substrate are exposed.

Further, according to the device manufacturing method of the present invention, there is an effect that the productivity of highly integrated devices can be improved.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a configuration of an exposure apparatus used in a first embodiment.

FIG. 2 is a flowchart for explaining the first embodiment of the exposure method according to the present invention.

FIG. 3 is a diagram for explaining a shot rotation error due to deformation of an X moving mirror.

FIG. 4 is a flow chart for explaining a second embodiment of the exposure method according to the present invention.

FIG. 5 is a flowchart for explaining a third embodiment of an exposure method according to the present invention.

FIG. 6 is a flowchart for explaining an embodiment of a device manufacturing method according to the present invention.

7 is a flowchart of the process in step 304 of FIG.

8A and 8B are views for explaining a shot orthogonality error due to deformation of an X moving mirror.

[Explanation of symbols]

100 ... Exposure device, R ... Reticle (mask), W ... Wafer (substrate).

Claims (14)

[Claims] 1. An exposure method for transferring a pattern formed on a mask onto a substrate, wherein each row and each column of the matrix among a plurality of partitioned regions formed in a matrix on the substrate. Obtaining position information of marks formed in a plurality of specific divided areas each including one of the divided areas; either row-by-row or column-by-column of the matrix based on the position information of the marks For obtaining a specific type of transfer error information relating to the partitioned area of the plurality of partitions while correcting the specific type of transfer error for each row or column of the matrix using the transfer error information. A step of sequentially transferring the pattern of the mask onto a region, and an exposure method. 2. The method further includes a step of obtaining information on a transfer error other than the specific type relating to the divided area by statistical calculation based on the position information of the mark, and when transferring the mask pattern, a transfer other than the specific type is performed. The exposure method according to claim 1, wherein a transfer error other than the specific type is also corrected based on error information. 3. The exposure method according to claim 1, wherein the information of the transfer error of the specific type is obtained by a statistical calculation process using the position information of the mark. 4. An exposure method for transferring a pattern formed on a mask onto a substrate in lot units, wherein n (n is a natural number) substrates from the beginning of the lot are arranged in a matrix on each substrate. Obtaining position information of marks formed in a plurality of specific partitioned areas each including one partitioned area in each row and each column of the matrix among the partitioned areas formed in step a.
Obtaining information on a specific type of transfer error relating to a partitioned area for each row or column of the matrix based on the position information of the mark; at least the above for all substrates in the lot. The transfer error of a specific type is sequentially corrected using the information of the transfer error of the specific type for each row or each column of the matrix, and the pattern of the mask is sequentially transferred to the plurality of divided areas. Exposure method. 5. The method further includes the step of obtaining information on a transfer error other than the specific type with respect to the divided area by statistical calculation based on the position information of the mark, and when transferring the mask pattern, transfer other than the specific type is performed. The exposure method according to claim 4, wherein a transfer error other than the specific type is also corrected based on error information. 6. The n is 2 or more, and the information of a specific type of transfer error regarding the divided area for each row or column of the matrix is obtained for n substrates from the top of the lot. The exposure method according to claim 4 or 5, wherein the exposure method is obtained by a statistical processing calculation using mark position information. 7. An exposure method for exposing different layers on a substrate by using a plurality of exposure devices that transfer a pattern formed on a mask onto a substrate, wherein the plurality of exposure devices are individually used. Transferring the pattern of the mask onto a plurality of substrates to form a plurality of partitioned areas in a matrix arrangement on each substrate; a plurality of partitioned areas formed in a matrix arrangement on each substrate A step of obtaining the positional information of the marks formed in a plurality of specific divided areas, and the information of a specific type of transfer error regarding the divided areas for each substrate based on the positional information of the marks obtained for each substrate. Asked
A step of storing as information on a transfer error of a specific type relating to a divided area of the exposure apparatus corresponding to each substrate; and when performing overlay exposure using any exposure apparatus of the plurality of exposure apparatuses, While correcting the transfer error of the specific type in consideration of the information of the transfer error of the specific type regarding the specific exposure device that has performed exposure of the layer to be overlapped among the layers up to the front layer of the substrate, A step of superimposing and sequentially transferring a mask pattern on a transfer area arranged in a matrix on the substrate to be exposed, 8. An exposure method for exposing different layers on a substrate by using a plurality of exposure devices for transferring a pattern formed on a mask onto a substrate, wherein the plurality of exposure devices are individually used. Transferring the pattern of the mask onto a plurality of substrates to form a plurality of partitioned areas in a matrix arrangement on each substrate; a plurality of partitioned areas formed in a matrix arrangement on each substrate A step of obtaining the positional information of the marks formed in a plurality of specific divided areas, and the information of a specific type of transfer error regarding the divided areas for each substrate based on the positional information of the marks obtained for each substrate. Asked
A step of storing as information of a transfer error of a specific type relating to a divided area of the exposure device corresponding to each substrate; and when performing exposure using any exposure device of the plurality of exposure devices, A pattern of a mask on the substrate to be exposed while correcting the transfer error of the specific type in consideration of the information of the transfer error of the specific type related to a specific exposure apparatus used for exposing a specific layer after the next layer. Sequentially forming a plurality of partitioned areas in a matrix arrangement, and exposing the same. 9. The specific plurality of partitioned areas is one of the partitioned areas in each row and each column of the matrix among the plurality of partitioned areas formed in a matrix arrangement on each substrate. A plurality of divided areas including one, the information of a specific type of transfer error regarding the divided areas of the exposure device corresponding to each substrate, the matrix obtained based on the position information of the marks of the specific plurality of divided areas 9. The exposure method according to claim 7, further comprising information on a specific type of transfer error relating to a divided area for each of the rows and the columns. 10. The specific plurality of partitioned areas are all partitioned areas on each of the substrates, and statistical processing calculation is performed using measured position information of each mark and position information of the mark. Non-linear component of the amount of positional deviation of the exposure apparatus corresponding to each substrate is obtained by obtaining a non-linear component of the amount of positional deviation of each of the divided regions based on the position information of each of the divided regions used for alignment with the obtained predetermined point. And a step of storing as a correction value for the component, the information of the transfer error of the specific type of the specific exposure apparatus when performing exposure using an arbitrary exposure apparatus of the plurality of exposure apparatuses. In addition, the correction value for the non-linear component of the positional deviation amount of the specific exposure apparatus is also taken into consideration to correct the transfer error and the positional deviation amount of the specific type related to the divided area, and the mass area is divided into the plurality of divided areas. The exposure method according to any one of claims 7-9, characterized in that sequentially transferring the pattern of. 11. An exposure method for transferring a pattern formed on a mask onto a substrate in lot units, wherein n (n is a natural number) substrates from the beginning of the lot are arranged in a matrix on each substrate. Measuring the positional information of the marks formed respectively corresponding to the plurality of divided areas formed by the above; and the statistical processing using the measured positional information of the respective marks and the positional information of the marks. A step of obtaining a non-linear component of the positional displacement amount of each of the divided areas based on the positional information of each of the divided areas used for alignment with a predetermined point obtained by calculation; and the measured position information of the mark A step of obtaining information on a specific type of transfer error relating to a divided area for each row or column of the matrix based on , At least the transfer error of the specific type is corrected for each row or column of the matrix by using the transfer error information, and while correcting the non-linear component of the positional deviation amount of each of the divided areas, A step of sequentially transferring the pattern of the mask to a plurality of partitioned areas; 12. The information of a specific type of transfer error relating to a partitioned area for each row or column of the matrix is obtained by an external measuring device. 11. The exposure method according to any one of 11. 13. The exposure method according to claim 1, wherein the specific type of transfer error includes at least one of an orthogonality error and a rotation error of a coordinate axis of the partitioned area. . 14. A device manufacturing method including a lithography process, wherein the exposure method according to any one of claims 1 to 13 is used in the lithography process.