JP2003151874A - Position detecting method, exposure method and exposure equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position detecting method capable of finding the positional information of each section zone on a substrate with good accuracy. SOLUTION: At the time of successively obtaining the measured positional information of at least three specific section zones of a plurality of section zones on a substrate, a mark attached to each specific section zone individually is detected after the substrate is moved along a moving path in the specific direction (step 409 to 421). Thus, the detection error of the mark due to a difference in the direction of the moving path of the substrate can be reduced. Thereby, information with high accuracy can be obtained as the measured positional information of the specific section zone. Consequently, the positional information used for alignments with respective predetermined points at the plurality of section zones is calculated by a statistical operation by using each measured positional information (step 423) so as to permit the positional information of each section zone on the substrate to be found with good accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detection method, an exposure method and an exposure apparatus, and more particularly to a position detection method for detecting position information of a plurality of partitioned areas arranged on a substrate, and the position detection. The present invention relates to an exposure method using the method and an exposure apparatus suitable for carrying out the position detection method.

[0002]

2. Description of the Related Art In recent years, a step-and-repeat type or step-and-scan type exposure apparatus, a wafer prober, a laser repair apparatus, or the like has been used in the manufacturing process of devices such as semiconductor elements. In these devices, a plurality of chip pattern areas (shot areas) regularly (matrix) arranged on the substrate.
Position of each of the above with respect to a predetermined reference point (for example, processing point of various devices) in a stationary coordinate system (that is, a Cartesian coordinate system defined by a laser interferometer) that defines the moving position of the substrate. It is necessary to align them.

Particularly, in an exposure apparatus, when aligning a substrate (semiconductor wafer, glass plate, etc.) with a projection position of a pattern formed on a mask or a reticle (hereinafter, collectively referred to as a "reticle"), a manufacturing step is performed. In order to prevent a decrease in yield due to the occurrence of defective products in the above chips, it is desired that the alignment accuracy be constantly maintained with high accuracy.

Usually, in the exposure process, a circuit pattern (reticle pattern) of 10 or more layers is superposed and transferred onto the wafer, but if the superposition accuracy between the respective layers is poor, the characteristics of the circuit will be inconvenient. There is. In such a case, the chip does not satisfy the desired characteristics, and in the worst case, the chip becomes a defective product and the yield is reduced. Therefore, in the exposure step, an alignment mark is previously attached to each of the plurality of shot areas on the wafer,
The mark position (coordinate value) on the stage coordinate system is detected. Thereafter, wafer alignment is performed to align (position) one shot area on the wafer with the reticle pattern based on the mark position information and the position information of the known reticle pattern (which is premeasured). Be seen.

There are roughly two types of wafer alignment, and one is a die-by-die (D / D) alignment method in which the alignment mark is detected for each shot area on the wafer to perform alignment. . The other is a global alignment method in which alignment of each shot area is performed by detecting alignment marks of only some shot areas on the wafer to obtain the regularity of the arrangement of the shot areas. At present, the global alignment method is mainly used in the device manufacturing line in consideration of the throughput. In particular, at present, as disclosed in, for example, Japanese Patent Laid-Open Nos. 61-44429 and 62-84516, an enhanced method for precisely specifying the regularity of the arrangement of shot areas on a wafer by a statistical method is used.・ Global alignment (EGA) method is the mainstream.

The EGA method measures the position coordinates of only a plurality of shot areas (three or more are required, usually about 7 to 15 pieces) selected as specific shot areas in advance on one wafer, After calculating the position coordinates (arrangement of shot areas) of all shot areas on the wafer using the statistical calculation process (least square method etc.) from the measured values, the wafer stage is stepped according to the calculated arrangement of shot areas. It is something that goes. This EGA method has an advantage that a measurement time is short and an averaging effect can be expected with respect to a random measurement error.

Here, the statistical processing performed by the EGA method
The method of processing will be briefly described. M on wafer (m ≧ 3
Integers) specific shot areas (“sample shots”
Also called "region" or "alignment shot region"
The designed array coordinates of _n, Y_n) (N = 1, 2,
..., m), and the deviation from the designed array coordinates (Δ
X_n, ΔY_n) Is linear as shown in the following equation (1)
Assuming a model.

[0008]

[Equation 1]

Further, when the deviation (measured value) of the actual arrangement coordinates of each of the m sample shot areas from the designed arrangement coordinates is (Δx _n , Δy _n ), this deviation and the above linear model are used. The residual sum of squares E of the deviation from the assumed designed array coordinates is expressed by the following equation (2).

[0010]

[Equation 2]

Therefore, the parameters a, b, c, d, e, and f that minimize this equation may be obtained. In the EGA method, the array coordinates of all shot areas on the wafer are calculated based on the parameters a to f calculated as described above and the designed array coordinates.

[0012]

In the wafer alignment of the EGA method described above, when measuring the position coordinates of the alignment shot area, the marks individually attached to each alignment shot area can be sequentially detected by the alignment detection system. Has been done. At this time, the conventional E
In the GA type wafer alignment, a substrate movement path (usually a polygonal movement path) in which the movement between marks to be detected is the shortest distance has been adopted in order to maximize throughput.

However, recently, when transferring an ultrafine pattern having a device rule (practical minimum line width) of 130 μm or less, a mark position detection error by a level of alignment detection system which cannot be ignored occurs. It turned out to be. It is considered that, up to now, such a detection error of the alignment detection system could be ignored.

It is certain that the semiconductor device will be highly integrated in the future and the device rule will be further miniaturized accordingly. In order to cope with this, it is inevitable that the exposure apparatus is required to further improve its performance, and the detection error of the alignment detection system may become an obstacle to the achievement of the total overlay error that should be achieved by the future exposure apparatus. .

The present invention has been made under such circumstances, and a first object thereof is to provide a position detecting method capable of accurately obtaining position information of each partitioned area on a substrate.

A second object of the present invention is to provide an exposure method and an exposure apparatus capable of accurately forming a predetermined pattern in each partitioned area on a substrate.

[0017]

As a result of various experiments (including simulations) conducted by the inventor and others, as a result of repeated studies, the characteristics relating to the movement of the substrate stage (substrate) are slightly different when the directions are different. Therefore, in wafer alignment that employs movement paths in which the movement direction of the substrate is different immediately before the detection of the target mark, the difference in the movement direction of the substrate stage at the time of detecting the mark causes the detection error of the alignment detection system described above. It was found to be one of the major factors. The present invention has been made based on the novel findings obtained by the inventors, and adopts the following configurations (means).

According to a first aspect of the present invention, there is provided a position detecting method for detecting position information used for alignment with a predetermined point in each of a plurality of divided areas on the substrate, wherein the substrate is moved in a specific direction. A step of sequentially obtaining a plurality of actually measured position information obtained by detecting the mark on the substrate after moving along the line; and a predetermined point in each of the plurality of divided areas by statistical calculation using the actually measured position information. And a step of calculating position information used for position alignment of the position detection method.

In this specification, "positional information" means the amount of positional deviation from the design value of each specific divided area, or the relative position of each divided area with respect to a predetermined reference position (for example, for a mask in the case of an exposure apparatus). Position of the partitioned area on the board),
It includes all information about the position of each partitioned area, such as the center-to-center distance between the partitioned areas. Further, "alignment with a predetermined point in each of a plurality of partitioned areas on the substrate" is a concept including an operation of suppressing relative positional deviation between the mask and the substrate (shot area) during scanning exposure within an allowable range. is there. Here, the mark has some correspondence with at least one partitioned area on the substrate, and the correspondence is known when the mark is detected.

According to this, when the predetermined actually measured position information (position information obtained by detecting the mark) is sequentially obtained, the mark on the substrate is moved after the substrate is moved along the movement path in the specific direction. To be detected. Therefore, it is possible to reduce the above-described mark detection error caused by the difference in the direction of the movement path of the substrate (in the case of an actual device, the substrate stage on which the substrate is mounted). Thereby, highly accurate information can be obtained as the measured position information. Therefore, the position information of each partitioned area on the substrate can be accurately obtained by calculating the positional information used for alignment with a predetermined point in each of the plurality of partitioned areas by statistical calculation using each measured position information. It will be possible.

In this case, the detected mark is a mark individually attached to at least three specific partition areas on the substrate, and the measured position information is position information regarding each of the specific partition areas. Can be

In each of the position detecting methods described in claims 1 and 2, after a predetermined time elapses after the movement of the substrate along the movement path in the specific direction is completed, a predetermined time is waited until the positioning is completed, Although it is possible to detect a mark, the moving state of the substrate along the moving path for detecting the mark is the deceleration immediately before the stop state as in the position detecting method according to claim 3. Including the state, at the time when the deceleration state transits to the stop state, the positioning can be settled to the same degree.

In each of the position detecting methods described in claims 1 to 3, as in the position detecting method described in claim 4, the movement state of the substrate along the movement path for detecting the mark is: An acceleration state up to the same target speed and a deceleration state in which the target speed transits to a stop state can be included.

In each of the position detecting methods described in claims 1 to 4, as in the position detecting method described in claim 5, the moving distance of the substrate along the moving path for detecting the mark is: The distance may be equal to or larger than a predetermined threshold.

In each of the position detecting methods described in claims 1 to 5, as in the position detecting method described in claim 6, the actually measured position information is the predetermined point based on the design position information of the partitioned area. It is possible to calculate a parameter of a conversion formula for deriving the position information by the statistical calculation corresponding to the position deviation.

In each of the position detecting methods described in claims 1 to 6, as in the position detecting method described in claim 7, the actually measured position information is the stationary coordinate system defining the moving position of the substrate. The position information may be a coordinate value of a mark, and the position information may be a coordinate value on the stationary coordinate system of each of the divided areas.

The invention according to claim 8 is an exposure method which sequentially exposes a plurality of partitioned areas on a substrate to form a predetermined pattern in each of the partitioned areas, and the invention is any one of claims 1 to 7. A step of detecting the position information of each of the divided areas by using the position detection method described in the above item; and after sequentially moving each of the divided areas to an exposure reference position based on the detection result, exposing each of the divided areas. And an exposing step.

According to this, the position information of each partitioned area on the substrate can be accurately detected by using the position detecting method according to any one of claims 1 to 7. Then, each divided area is sequentially moved to the exposure reference position based on the position information, and then each divided area is exposed. Therefore, it is possible to accurately form a predetermined pattern in each partitioned area on the substrate.

According to a ninth aspect of the present invention, there is provided an exposure apparatus which sequentially exposes a plurality of divided areas on a substrate to form a predetermined pattern in each of the divided areas, and a substrate stage on which the substrate is placed. A mark detection system for detecting a mark existing on the substrate stage; a drive system for driving the substrate stage in at least a two-dimensional plane; and a position of the substrate stage in at least the two-dimensional plane. A position detection system; a mark on the substrate is detected using the mark detection system after moving the substrate stage on which the substrate is mounted via the drive system along a movement path in a specific direction, and Measured position information obtained based on the detection result,
A detection control device for sequentially detecting; a calculation device for calculating positional information used for alignment with a predetermined point in each of a plurality of divided areas by statistical calculation using the measured position information; and exposing each of the divided areas Immediately before, in order to sequentially move each partitioned area on the substrate to the exposure reference position, based on the position information calculated by the calculation device, the position detection system and the drive system are used to move the substrate stage of the substrate stage. An exposure apparatus including a movement control device that controls movement.

Here, similarly to the above, the mark has some correspondence with at least one divisional region on the substrate, and the correspondence is known when the mark is detected.

According to this, the detection control device detects the mark on the substrate by using the mark detection system after moving the substrate stage on which the substrate is mounted via the drive system along the movement path in the specific direction. Then, the measured position information obtained based on the detection result is sequentially detected. In this case, since the movement paths of the substrate stage are in the same direction, it is possible to reduce the mark detection error caused by the mark detection system due to the difference in the direction, and obtain highly accurate information as each measured position information. be able to.

Next, the calculating device calculates the position information used for the position alignment with the predetermined point in each of the plurality of divided areas by the statistical calculation using the above-mentioned measured position information.
This makes it possible to accurately obtain the position information of each partitioned area on the substrate.

Immediately before exposing each divided area, the movement control device sequentially moves each divided area on the substrate to the exposure reference position. Therefore, the position detection system is based on the position information calculated by the calculation device. And the drive system are used to control the movement of the substrate stage. Therefore, it becomes possible to accurately form a predetermined pattern in each partitioned area on the substrate.

In this case, as in the exposure apparatus according to the tenth aspect, the mark detected by the detection control device is a mark individually attached to at least three specific divided areas on the substrate, The measured position information can be position information regarding each of the specific divided areas.

In each of the exposure apparatuses described in claims 9 and 10, as in the exposure apparatus described in claim 11, the detection control device follows the movement path for detecting each of the actually measured position information. Controlling the movement of the substrate such that the movement state includes a deceleration state immediately before the stop state when the substrate is moved, and the positioning is settled to the same degree at the time of transition from the deceleration state to the stop state. Can be

In each of the above-mentioned exposure apparatuses according to claims 9 to 11, like the exposure apparatus according to claim 12, the detection control device follows the movement path for detecting each of the actually measured position information. The movement of the substrate may be controlled so that the movement state of the substrate includes an acceleration state up to the same target speed and a deceleration state in which the target speed transits to a stop state.

In each of the above-mentioned exposure apparatuses according to claims 9 to 12, like the exposure apparatus according to claim 13, the detection control device follows the movement path for detecting each of the actually measured position information. When the substrate is moved, the moving distance is
It is possible to control the movement of the substrate so that the same distance is equal to or more than a predetermined threshold value.

In each of the exposure apparatuses described in claims 9 to 13, like the exposure apparatus described in claim 14, the substrate stage can be of a floating type.

[0039]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIG.
~ It demonstrates based on FIG.

FIG. 1 shows an exposure apparatus 10 according to one embodiment.
A schematic configuration of 0 is shown. This exposure apparatus 100 is
This 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 (drive system) that drives 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 passing through the opening of the reticle blind passes through a relay lens system and a condenser lens system and illuminates a rectangular slit-shaped illumination area 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 at the center of a glass substrate as a mask substrate, and at least one pattern region is formed on both sides of the pattern region in the X-axis direction.
Pair of reticle alignment marks (neither 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. 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. The imaging characteristics (a part of the optical characteristics) such as magnification, distortion, coma, and field curvature 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).

On the bottom surface of the XY stage 20, a plurality of gas static pressure bearings (not shown), for example, air bearings are provided. The static pressure of the pressurized air ejected from the air bearings to the base surface (so-called pressure in the gap). ) And XY stage 2
The XY stage 20 and its mounted object are levitationally supported above the base surface through a predetermined clearance by a balance with 0 and its own weight (and preload) of the entire mounted object. As a drive device for the XY stage 20, for example, a magnetic levitation type linear actuator or the like may be used.
In this case, the XY stage 20 and its mounted object are levitationally supported above the base surface by the magnetic force.

The XY stage 20 not only moves 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 the 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 holding 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. Meter (hereinafter referred to as "wafer interferometer")
26) is provided so as to face the reflecting surface of the movable 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 wafer interferometer also has an X movable mirror. Although an X-wafer interferometer for measuring the directional position and a Y-wafer interferometer for measuring the Y-direction position are provided, they are shown as a movable mirror 24 and a wafer interferometer 26 as a representative in FIG. 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). The X-wafer interferometer and the Y-wafer interferometer are multi-axis interferometers having a plurality of length-measuring axes. In addition to the X and Y positions of the wafer table 18, rotation (θz rotation around the Z axis, X axis). It is also possible to measure rotation around θx rotation and rotation around Y axis). Therefore, in the following description, it is assumed that the wafer interferometer 26 measures the position of the wafer table 18 in the five-degree-of-freedom directions of X, Y, θz, θy, and θx. In addition, the coordinate system (X,
Y) is also referred to below as the stationary coordinate system.

The measurement value of the wafer interferometer 26 is the main controller 2
8 to the main controller 28, and the main controller 28 supplies the wafer 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.

On the wafer table 18, the reference plate FP is arranged so that its surface is at the same height as the surface of the wafer W.
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 a mark detection system. As the alignment detection system AS, for example, an alignment mark (or a reference mark on the reference plate FP) on the wafer W, which is imaged by a CCD camera or the like, is illuminated with light having a wide wavelength band using a halogen lamp or the like as a light source. An FIA (Field Image Alignment) type off-axis alignment sensor for image processing image data to measure a mark position is used.

The alignment control device 16 performs A / D conversion of the information from the alignment detection system AS, and refers to the measurement value of the wafer interferometer 26 to detect the mark position. The detection result is supplied from the alignment controller 16 to the main controller 28.

Further, in the exposure apparatus 100 of this 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 the R or a reference mark on the reticle stage RST (both not shown) and a mark on the reference plate FP. 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 comprises a so-called microcomputer (or workstation) including a CPU (central processing unit), memory (ROM, RAM), various interfaces and the like.

Next, the exposure processing operation in the exposure apparatus 100 configured as described above will be described with reference to the flowchart of FIG. The flowchart of FIG. 2 is
It corresponds to a series of processing algorithms executed by the CPU of main controller 28.

Here, the patterns of the second and subsequent layers formed on the reticle R are transferred onto the wafer W.
As a precondition, it is assumed that patterns and alignment marks up to the previous layer have already been formed in a plurality of shot areas on the wafer W.

In step 401 of FIG. 2, the reticle R designated on the reticle stage RST is loaded using a reticle loader (not shown).

At step 403, the wafer W is loaded on the wafer table 18 by using a wafer loader (not shown).

In step 405, the projection optical system P is detected by the reticle alignment microscope (not shown) described above.
Through L, the relative position of at least a pair of reference marks formed on the surface of the reference plate FP corresponding to at least a pair of the above-mentioned reticle alignment marks is detected. Then, from the measured values of the reticle interferometer 21 and the wafer interferometer 26 at that time, the reticle interferometer 2
The relationship between the reticle stage coordinate system defined by the length measurement axis 1 and the wafer stage coordinate system defined by the length measurement axis of the wafer interferometer 26 is obtained. That is, reticle alignment is performed in this manner.

In step 407, in order to perform wafer alignment by the above-mentioned EGA method, as an example, 8
Select sample shot areas. Then, as an example, as shown in FIG. 3 (A), the alignment marks attached to the sample shot areas are M (M _{1 to} M ₈ ).
And The number of sample shot areas may be three or more.

In step 409, the coordinate position of each alignment mark M, which is separated from the designed coordinate position on the stationary coordinate system by the predetermined distance L in the predetermined direction, is calculated, and the position is set to the starting point P (P _{1 to} P ₈ ). That is, the positional relationship between the designed coordinate position of the alignment mark M and the corresponding starting point P is the same for each of the alignment marks M _{1 to} M ₈ , and here, for convenience, FIG.
It is assumed that there is a relationship shown by a vector B in (A). A value equal to or larger than a predetermined threshold is used as the distance L. The threshold value is the minimum distance for detecting the alignment mark with high accuracy, and is the XY value at the time of detecting the alignment mark.
It depends on the moving speed (target speed) of the stage 20. The relationship between the target speed and the threshold value is measured in advance and stored in the RAM of main controller 28. Therefore, when the target speed is given, the threshold value can be uniquely obtained. For example, when the target speed is 175 mm / sec, a value of 10 mm is used as an example.

In step 411, in order to detect the alignment mark M, XY when the XY stage 20 is moved by the distance L from the starting point P in the direction indicated by the vector B.
The moving condition of the stage 20 is determined. Here, a moving condition is adopted in which the moving state of the XY stage 20 sequentially transits to an accelerating state, a constant velocity state, and a decelerating state. That is, the acceleration is determined so that the moving speed of the XY stage 20 smoothly reaches the target speed, and the XY stage 20 stops accurately at the position of the distance L from the starting point P, and at that time, the positioning is settled to a predetermined degree. Determine the deceleration as you are doing. The relationship between the target speed and the acceleration and deceleration is experimentally obtained in advance and stored in the RAM of the main controller 28 as a data table. Therefore, when the target speed is given, the optimum acceleration α1 and deceleration α2 can be obtained by referring to the data table and extracting the acceleration and deceleration corresponding to the target speed. And the deceleration α
Based on 2, the deceleration start position (Ld) is calculated.

At step 413, 1 is set to the counter k indicating the number of the alignment mark to be detected. Then, the alignment mark M ₁ is set as a detection target.

In step 415, the wafer stage drive system 22 is operated while monitoring the measurement value of the wafer interferometer 26 so that the starting point P _k (k = 1 in this case) is located at the detection center of the alignment detection system AS. Through XY stage 2
Move 0.

At step 417, the movement of the XY stage 20 is started in the direction indicated by the vector B with the acceleration α1. Then, based on the measurement value of the wafer interferometer 26, XY
When it is confirmed that the moving speed of the stage 20 has reached the target speed, the acceleration is stopped and the target speed is maintained. Next, when it is confirmed that the movement distance of the XY stage 20 has reached Ld based on the measurement value of the wafer interferometer 26, the deceleration α2
Start deceleration with. Furthermore, when it is confirmed that the moving distance of the XY stage 20 has reached L and the XY stage 20 has stopped, the position of the alignment mark M _k (k = 1 in this case) is detected with the detection center of the alignment detection system AS as a reference. To do.

In step 419, the value of the counter k is referred to, and it is determined whether or not the detection of the last alignment mark has been completed, that is, whether or not the positions of all the selected alignment marks have been detected. Where k
Since = 1, the determination in step 419 is denied and the process proceeds to step 421.

At step 421, the value of the counter k is incremented (+1) to the next alignment mark M _k.
Is detected and the process proceeds to step 415.

Thereafter, the processes and judgments of steps 415 → 417 → 419 → 421 are carried out until the judgment of step 419 is affirmed.

For all the selected alignment marks M
When the position detection is completed, the determination in step 419 is affirmative
Then, the process proceeds to step 423. That is, this embodiment
In the state, as shown in FIG.
Outgoing AS is P₁→ M₁→ P _Two→ M_Two→ P_Three→ M_Three→ P
_Four→ M_Four→ P₅→ M₅→ P₆→ M₆→ P₇→ M₇→ P ₈
→ M₈Relative to the wafer W in this order. Actually
The alignment detection system AS is fixed and the wafer W is moved.
However, in FIG.
Element detection system AS is described as moving.
It As a result, the alignment mark M₁~ M₈Detection of
Immediately before that, move the XY stage 20 in the same direction.
It is performed after moving the same distance under the same movement condition.

At step 423, so-called EGA calculation for calculating the array coordinates of all shot areas is performed based on the detection result of the selected alignment mark M by the statistical processing method performed by the above-mentioned EGA method.
As a result, the array coordinates of all shot areas on the wafer W on the stationary coordinate system are calculated.

In step 425, the counter j indicating the array number of the shot area is set to 1 and the first shot area is set as the exposure target area.

In step 427, the XY stage is set so that the position of the wafer W becomes the acceleration start position for exposing the exposure target area on the wafer W based on the array coordinates of the exposure target area calculated by the EGA calculation. 20 is moved, and the reticle stage RST is moved so that the position of the reticle R becomes the acceleration start position.

In step 429, 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 above relative scanning is performed by controlling the wafer stage drive system 22 and the reticle stage drive system 29 while monitoring the measurement values of the wafer interferometer 26 and the reticle interferometer 21. Then, different areas of the pattern area of the reticle R are sequentially illuminated with the illumination light IL,
The scanning exposure is completed when the illumination of the entire pattern area is completed. As a result, the pattern of the reticle R is reduced and transferred onto the exposure target area on the wafer W via the projection optical system PL.

In step 431, the counter j is referred to, and it is determined whether or not exposure has been performed on all shot areas. Here, j = 1, that is, only the exposure is performed on the first shot area, so the determination at step 431 is denied, and the routine proceeds to step 433.

In step 433, the value of the counter j is incremented (+1) to set the next shot area as the exposure target area, and the process returns to step 427.

Thereafter, the processings and judgments in steps 427 → 429 → 431 → 433 are repeated until the judgment in step 431 is affirmed.

When the transfer of the pattern to all the shot areas on the wafer W is completed, the determination at step 431 is affirmative, and the process proceeds to step 435.

At step 435, a wafer loader (not shown) is instructed to unload the wafer W. As a result, the wafer W is unloaded from the wafer table 18 by the wafer loader (not shown), and then the wafer W is transferred to the coater / developer (not shown) connected inline to the exposure apparatus 100 by the wafer transfer system (not shown). Be transported. Then, the exposure processing operation ends.

As is clear from the above description, in the position detecting method according to the present embodiment, steps 409-4 of FIG.
The process of 21 corresponds to the process of sequentially obtaining the measured position information, and the process of step 423 corresponds to the process of calculating the position information.

Further, in the exposure apparatus according to this embodiment, the wafer interferometer 26 and the main controller 28 constitute a position detection system, and the main controller 28 constitutes a detection controller, a calculator and a movement controller. To be done.

As described above, according to the position detecting method according to the present embodiment, the starting point separated by the predetermined distance in the predetermined direction from the designed position of the alignment mark is selected for each selected alignment mark. Since each is calculated and the XY stage 20 is moved from the starting point to detect the alignment mark, the moving direction of the XY stage 20 immediately before the detection is the same direction for all the alignment marks. Therefore, it is possible to reduce the above-described detection error of the alignment mark due to the difference in the moving direction of the XY stage 20. That is, the position information of each sample shot area can be accurately obtained.

Further, according to the present embodiment, since the EGA calculation is performed based on the detection result of the selected alignment mark, the parameters a ...
f can be calculated with high precision, and as a result, the array coordinates of each shot area can be obtained with high precision.

Further, according to this embodiment, when the XY stage 20 is moved to the alignment mark detection position, the positioning is settled to the same degree when the XY stage 20 transits from the deceleration state to the stop state. In addition, since the movement condition of the XY stage 20 is set, the alignment mark can be detected in a short time after the XY stage 20 reaches the detection position, and the decrease in throughput can be suppressed. .

Further, according to the present embodiment, since the moving condition in which the moving state of the XY stage 20 sequentially transits to the accelerating state, the constant velocity state and the decelerating state is adopted, the speed does not change suddenly. , The movement condition of the XY stage 20 can be set so that the positioning is settled to the same degree at the time when the XY stage 20 transits from the deceleration state to the stop state. Therefore, it is possible to suppress the decrease in throughput and improve the accuracy of detecting the alignment mark.

Further, according to the present embodiment, the acceleration α1 is determined so that the moving speed of the XY stage 20 does not suddenly change, so that the moving state of the XY stage 20 can be accurately known. That is, the movement control of the XY stage 20 can be performed with high accuracy, and as a result, the position information of each sample shot area can be obtained with high accuracy.

Further, according to this embodiment, the starting point P is
Since the distance L from the designed position of the alignment mark M is set to a predetermined threshold value or more, the movement control of the XY stage 20 can be stably performed, and as a result, each sample shot area The position information can be accurately obtained. Here, the value of the distance L is changed, the alignment mark M is detected, and E is detected based on the detection result.
Fig. 4 shows an example of the results of GA calculation and residual error measurement.
Is shown in. By the way, in the formula (1), the parameters a to f are used for simplification of the description.
Each of these parameters is an error parameter for the next six wafers (hereinafter, referred to as “wafer parameter”), that is, rotation θ (wafer rotation) for the arrangement of each shot area on the wafer, and scaling in the X and Y directions. (Linear expansion / contraction of wafer) This corresponds to a predetermined combination or replacement of six parameters of Sx, Sy, orthogonality Ort, and offsets Ox, Oy in the X and Y directions. In other words, by obtaining the parameters a to f, the above six wafer parameters can be obtained. FIG. 4 shows the residual errors regarding the rotation, orthogonality, and linear expansion and contraction (X direction and Y direction) of the wafer thus obtained. When the distance L is 10 mm or more, each residual error is extremely small. Has become.

In the present embodiment, since the movement between the alignment marks is not the shortest distance, the throughput is lower than in the conventional case. For example, when eight alignment marks are detected at the target speed of 175 mm / sec, the throughput is reduced. Is about 3 seconds, which is hardly a problem in the actual process.

Further, according to the exposure method of the present embodiment, the position of the wafer W is the acceleration start position for exposing the shot area on the wafer W based on the accurately calculated array coordinates of the shot area. Then, the exposure is performed. Therefore, the reticle pattern can be accurately formed in each shot area on the wafer W.

Further, according to the exposure apparatus of the present embodiment, X when detecting each selected alignment mark.
Since the moving direction of the Y stage 20 is fixed,
It is possible to reduce the above-described detection error of the alignment mark due to the difference in the moving direction of the XY stage 20.
That is, the position information of each sample shot area can be accurately obtained. Next, since the EGA calculation is performed using the highly accurate position information, the array coordinates of each shot area can be accurately obtained. Immediately before exposing the shot area, the XY stage 20 is moved so that the position of the wafer W becomes the acceleration start position for exposing the shot area on the wafer W based on the array coordinates calculated with high accuracy. To control. Therefore, the reticle pattern can be accurately formed in each shot area on the wafer W.

In the above embodiment, the XY stage 20 at the time of detecting the alignment mark (hereinafter referred to as “sample mark”) attached to the sample shot area.
The case where the moving state of the wafer W (that is, the wafer W) has the same acceleration and deceleration and the same moving distance has been described, but the present invention is not limited to this. That is, at least one of the acceleration, deceleration, and moving distance of the XY stage at the time of detecting each sample mark may be different, that is, the moving direction of the XY stage 20 at the time of detecting each sample mark is the same. It should be in the direction. Even in such a case, the detection of mark position information due to the difference in the characteristic relating to the movement of the XY stage 20 (for example, the mechanical movement characteristic of the XY stage 20) due to the difference in the moving direction of the XY stage 20 It is possible to effectively suppress the occurrence of error. However, if the movement distance is too short, the positioning and setting time of the XY stage becomes too long, which rather lowers the throughput. Therefore, it is desirable that the movement distance be a predetermined value or more.

Further, in the above embodiment, the case where the off-axis type FIA system (imaging type alignment sensor) is used as the alignment detection system has been described, but the invention is not limited to this, and any off-axis type alignment detection is performed. A system may be used. That is, the imaging method (image processing method) used in the FIA system or the like as the detection method.
Other than the above, for example, a method of detecting diffracted light or scattered light (LSA
(Laser Step Alignment) system, LIA (Laser Interfer)
(ometric Alignment) system) or the like. For example, an alignment mark on the wafer W is irradiated with a coherent beam almost vertically, and diffracted light of the same order (± first order, ± second order, ..., ±) generated from the alignment mark.
An alignment detection system for interfering and detecting (n-th order diffracted light) may be used. In this case, the diffracted light is detected independently for each order,
The detection result of at least one order may be used, or a plurality of coherent beams having different wavelengths may be applied to the alignment mark and diffracted light of each order may be interfered for each wavelength for detection.

The alignment detection system is an on-axis system (for example, TTL (Through The Lens) system).
But good. Further, the alignment detection system is not limited to one that detects the alignment mark in a state where the alignment mark is substantially stationary within the detection field of view of the alignment detection system. Relative movement method, such as L described above
The SA type or the homodyne LIA type may be used. In the case of the method of relatively moving the detection light and the alignment mark, it is desirable that the relative movement direction be the same as the movement direction of the XY stage 20 when detecting each of the alignment marks described above.

In the above embodiment, the coordinate value of the alignment mark in the sample shot area on the stationary coordinate system is used in the EGA calculation.
For example, the positional deviation amount from the designed coordinate value may be calculated for each shot area by statistical calculation using the positional deviation amount between the alignment mark and the mark on the reticle R or the index mark of the alignment detection system AS. Alternatively, the correction amount of the step pitch between the shot areas may be calculated. That is, as long as it is the positional information regarding the alignment mark and the information is appropriate for the statistical processing, any information may be used to perform the statistical calculation.

Further, in the above embodiment, the description has been made on the premise of the EGA system. However, instead of the EGA system, a so-called weighted EGA system disclosed in detail in, for example, Japanese Patent Laid-Open No. 5-304077 may be used. Alternatively, for example, a so-called in-shot multipoint EGA method disclosed in JP-A-6-349705 or the like may be used.

In the weighted EGA method, the position coordinates on the stationary coordinate system of at least three preselected sample shot areas among a plurality of shot areas on the wafer are measured. Then, for each shot area on the wafer,
Depending on the distance between the shot area (its center point) and each of the sample shot areas (its center point), or the distance between the shot area and a predetermined point of interest previously defined on the wafer, According to the distance between the point of interest and each of the sample shot areas, each position coordinate on the stationary coordinate system of the sample shot area is weighted,
In addition, by performing statistical calculation (least squares method, simple averaging process, etc.) using the weighted plurality of position coordinates, the position coordinates of each of the plurality of shot areas on the wafer on the stationary coordinate system are calculated. decide. Then, based on the determined position coordinates, each of the plurality of shot areas arranged on the wafer is aligned with a predetermined reference position in the stationary coordinate system.

In the intra-shot multipoint EGA method, a plurality of alignment marks are detected for each sample shot area to obtain a plurality of X and Y coordinates, respectively.
In addition to the wafer parameters corresponding to the expansion and contraction and rotation of the wafer used in the method, a model function including at least one of shot area rotation error, orthogonality, and shot parameter (chip parameter) corresponding to scaling is used as a parameter. The position information of each shot area, for example, the coordinate value is calculated by using this. Then, based on the determined position coordinates, each of the plurality of shot areas arranged on the wafer is aligned with a predetermined reference position in the stationary coordinate system.

Furthermore, in the above-described embodiment, the EGA method is assumed to be used, but any alignment method may be used, or an alignment mark may not be provided in each shot area. You may use the several alignment mark formed. In short, the same effect can be obtained by applying the present invention as long as a plurality of marks on an object are sequentially detected.

Further, in the above-described embodiment, the substrate is moved along the movement path in the specific direction when each of the plurality of marks is detected. Therefore, the movement locus of the substrate in the detection of all marks should be minimized as in the conventional method. However, one may be selected from a plurality of alignment modes such that the above-described embodiment is adopted in the accuracy-oriented mode and the conventional method is adopted in the throughput-oriented mode.

Further, for example, Japanese Patent Laid-Open No. 10-312961
In the gazette, there are combinations of mark visiting orders (n! (N factorial)) for detecting all alignment marks.
From among the above, various search methods (eg, linear programming, Lin
&Kernighan's solution method, K-Opt method, or genetic algorithm). Therefore, the method disclosed in the above publication is applied to the present invention, that is, in consideration of the moving direction and the moving distance of the substrate at the time of detecting each mark, the optimum moving sequence (the moving path of the substrate) by the above searching method is considered. ) May be determined.
As a result, it is possible to minimize the increase in the moving distance of the substrate caused by the application of the method disclosed in the above embodiment.

Further, in the above-mentioned embodiment, the case where the present invention is applied to the step-and-scan type scanning exposure apparatus has been described, but it goes without saying that the applicable range of the present invention is not limited to this. That is, it can be suitably applied to a step-and-repeat method, a step-and-stitch method, a mirror projection aligner, a photo repeater, and the like. Furthermore, the projection optical system PL may be any of a refraction system, a catadioptric system, and a reflection system, and may be any of a reduction system, a unity magnification system, and an enlargement system.

Further, 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 present invention is applicable not only to an exposure apparatus used for manufacturing a semiconductor element, but also for manufacturing a display including a liquid crystal display element, a plasma display, etc., for exposing a device pattern onto a glass plate, 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.

[0107]

As described above, the position detecting method according to the present invention has an effect that the position information of each partitioned area on the substrate can be accurately obtained.

Further, according to the exposure method and the exposure apparatus of the present invention, there is an effect that a predetermined pattern can be accurately formed in each divided area on the substrate.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a configuration of an exposure apparatus according to an embodiment.

FIG. 2 is a flowchart for explaining an embodiment of the present invention.

FIG. 3A is a diagram for explaining a relationship between an alignment mark and a starting point, and FIG. 3B is a diagram for explaining a movement path of a wafer when an alignment mark is detected. is there.

FIG. 4 is a diagram for explaining a relationship between a distance L and a residual error.

[Explanation of symbols]

20 ... XY stage (substrate stage), 22 ... Wafer stage drive system (drive system), 26 ... Wafer interferometer (part of position detection system), 28 ... Main controller (part of position detection system,
Detection control device, calculation device, movement control device), AS ... Alignment detection system (mark detection system), W ... Wafer (substrate).

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2F069 AA03 BB15 GG04 GG07 GG45                       GG58 GG59 HH09 MM24 NN08                       NN25                 2H097 CA13 GB00 KA03 LA10                 5F031 CA02 CA05 CA07 FA01 FA02                       FA04 FA07 HA13 HA53 JA01                       JA06 JA13 JA14 JA17 JA19                       JA28 JA30 JA38 JA45 JA50                       KA06 KA07 LA03 LA04 LA09                       MA27                 5F046 DB04 DB10 FC04 FC06

Claims (14)

[Claims] 1. A position detecting method for detecting position information used for alignment with a predetermined point in each of a plurality of partitioned areas on a substrate, the method comprising: moving the substrate along a moving path in a specific direction; A step of sequentially obtaining a plurality of actually measured position information obtained by detecting a mark on the substrate; a position used for alignment with a predetermined point in each of the plurality of divided areas by statistical calculation using the actually measured position information A position detecting method including a step of calculating information. 2. The detected mark is a mark individually attached to at least three specific partition areas on the substrate, and the actually measured position information is position information regarding each of the specific partition areas. The position detecting method according to claim 1, characterized in that 3. The movement state of the substrate along the movement path for detecting the mark includes a deceleration state immediately before a stop state, and when the transition from the deceleration state to the stop state occurs, positioning is performed. The position detection method according to claim 1, wherein the positions are set to the same degree. 4. The movement state of the substrate along the movement path for detecting the mark includes an acceleration state up to the same target speed and a deceleration state in which the target speed transits to a stop state. The position detecting method according to any one of claims 1 to 3. 5. The moving distance of the substrate along the moving path for detecting the mark is a distance equal to or more than a predetermined threshold value, according to any one of claims 1 to 4. Position detection method. 6. The measured position information corresponds to a position deviation from the predetermined point based on design position information of the partitioned area, and a parameter of a conversion formula for deriving the position information is calculated by the statistical calculation. The position detection method according to claim 1, wherein 7. The measured position information is a coordinate value of the mark on a stationary coordinate system that defines a moving position of the substrate, and the position information is a coordinate value on the stationary coordinate system of each of the partitioned areas. The position detecting method according to claim 1, wherein 8. The position detecting method according to claim 1, which is an exposure method of sequentially exposing a plurality of partitioned areas on a substrate to form a predetermined pattern in each of the partitioned areas. The step of detecting the positional information of each of the partitioned areas using the above; and the step of exposing each of the partitioned areas after sequentially moving the partitioned areas to an exposure reference position based on the detection result. Method. 9. An exposure apparatus that sequentially exposes a plurality of divided areas on a substrate to form a predetermined pattern in each of the divided areas, the substrate stage on which the substrate is mounted; A mark detection system for detecting existing marks; a drive system for driving the substrate stage in at least a two-dimensional plane; a position detection system for detecting a position of the substrate stage in at least the two-dimensional plane; The mark on the substrate is detected by using the mark detection system after moving the substrate stage on which the substrate is mounted via a system along a movement path in a specific direction, and is obtained based on the detection result. A detection control device that sequentially detects actually measured position information; and calculates position information that is used for alignment with a predetermined point in each of a plurality of divided areas by statistical calculation using each actually measured position information. And a position detection system based on the position information calculated by the calculation device for sequentially moving each divided region on the substrate to the exposure reference position immediately before exposing each divided region. And a movement control device that controls the movement of the substrate stage using the drive system. 10. The mark detected by the detection control device is a mark individually attached to at least three specific divided areas on the substrate, and the actually measured position information is:
The exposure apparatus according to claim 9, wherein the exposure information is position information regarding each of the specific partitioned areas. 11. The deceleration state, wherein the detection control device includes a deceleration state immediately before a stop state when the substrate is moved along the movement path for detecting each of the actually measured position information. 11. The exposure apparatus according to claim 9, wherein the movement of the substrate is controlled so that the positioning is settled to the same degree at the time of transition from the stop state to the stop state. 12. The detection control device, when moving the substrate along the moving path for detecting each of the actually measured position information, moves from the acceleration state up to the same target speed and the target speed. The exposure apparatus according to any one of claims 9 to 11, wherein the movement of the substrate is controlled so as to include a deceleration state that transits to a stop state. 13. The detection control device is configured such that, when the substrate is moved along the movement route for detecting each of the actually measured position information, the movement distance is equal to or more than a predetermined threshold value. The exposure apparatus according to any one of claims 9 to 12, which controls the movement of the substrate. 14. The exposure apparatus according to claim 9, wherein the substrate stage is a floating type.