JP2002296755A - Mask, position control accuracy measuring method, exposing method and device production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mask which can be suitably used for measuring the position control accuracy of a mask stage or substrate stage. SOLUTION: The mask is provided with a mask substrate (42) formed on a pattern plane (PA) so that the pattern of a first pair including a first pattern (TP1) and a second pattern (TP2), with which the form of an overlapped part is fixed without depending on an overlapping position in the case of overlapped transfer, and the pattern of a second pair including a third pattern (TP3) and a fourth pattern (TP4), with which the form of an overlapped part is changed while depending on a relative overlapping position in the case of overlapped transfer, having the same mutual position relation as a position relation between the first and second patterns can not be overlapped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a mask, a position control accuracy measuring method and an exposure method, and a device manufacturing method. More specifically, the present invention relates to a mask suitable for use in measuring the position control accuracy of a mask or a substrate, etc. Position of a mask (mask stage) or a substrate (substrate stage) using the mask;
Alternatively, a position control accuracy measuring method for measuring control accuracy of a relative position between the two, and an exposure for controlling at least one of a mask and a substrate based on the position control accuracy measured by the position control accuracy measuring method to perform exposure. And a device manufacturing method using the exposure method.

[0002]

2. Description of the Related Art Conventionally, in a lithography process for manufacturing a semiconductor device, a liquid crystal display device, or the like, a pattern formed on a mask or a reticle (hereinafter, collectively referred to as a “reticle”) is resisted through a projection optical system. There is used an exposure apparatus that transfers a wafer or a glass plate or the like onto which a substrate or the like is applied (hereinafter, also appropriately referred to as a “wafer”). In recent years, as an apparatus of this kind, from the viewpoint of emphasizing throughput, a step-and-repeat type reduction projection exposure apparatus (so-called “stepper”) or a step-and-scan type scanning type apparatus which is an improvement of this stepper has been used. 2. Description of the Related Art Sequentially moving projection exposure apparatuses such as exposure apparatuses are relatively frequently used.

In a step-and-repeat reduction projection exposure apparatus, a reticle pattern is transferred to a predetermined area on a wafer, and then the wafer is moved by a predetermined amount in a predetermined direction, and the reticle is moved to a next area on the wafer. Transfer the pattern. That is, positioning control of the wafer is performed before exposure. In a scanning exposure apparatus, exposure is performed while a reticle and a wafer are moved synchronously.

Semiconductor elements (integrated circuits) and the like are becoming highly integrated year by year, and accordingly, a projection exposure apparatus which is a manufacturing apparatus for semiconductor elements and the like is required to transfer a finer pattern with high precision. It has become. In order to transfer a pattern onto a wafer with high accuracy, it is necessary to transfer a reticle pattern accurately to a predetermined region on the wafer.

For this purpose, the wafer must be moved exactly in a predetermined direction by a predetermined amount. The movement of the wafer is performed by moving a wafer stage provided in the exposure apparatus and holding the wafer, and the position control accuracy of the wafer stage greatly affects the transfer accuracy. Further, in the case where a plurality of patterns are transferred while being superimposed on a plurality of layers (layers) on a wafer, higher position control accuracy is required.

In particular, in a scanning exposure apparatus, the position of the reticle (reticle stage) and the position of the wafer (wafer stage) at the start of scanning (start of acceleration), and the positional relationship between the two, depend on the pattern transfer accuracy and overlay. In addition to affecting the alignment accuracy, the synchronization accuracy between the reticle stage and the wafer stage during exposure also has a significant effect on the pattern transfer accuracy and the overlay accuracy.

That is, since the position control accuracy of each of the reticle stage and the wafer stage and the synchronization accuracy between the reticle stage and the wafer stage greatly affect the quality and productivity (including the yield) of the product, the position control of the wafer stage is performed. It is strongly desired to improve the accuracy (in the case of a static exposure apparatus), the position control accuracy of each of the reticle stage and the wafer stage, and the synchronization control accuracy of both stages (in the case of a scanning exposure apparatus).

Conventionally, the above-described position control accuracy, for example, the measurement of the positioning accuracy of the wafer stage (wafer), is generally performed by the following procedure. That is, first, the measurement pattern formed on the pattern surface of the measurement reticle is transferred to a predetermined area on the wafer positioned at the projection position (exposure position) of the measurement pattern. Next, the wafer stage is moved by a predetermined movement amount in a predetermined direction, and another area on the wafer is positioned at a projection position of the measurement pattern. The movement of the wafer stage at this time is performed by the stage control device while monitoring the measurement value of a length measuring device (for example, a laser interferometer) that measures the amount of movement of the wafer stage. When the positioning of the wafer is completed, the measurement pattern is transferred to another area on the wafer. Next, the transferred wafer is developed, and the distance between transfer images (for example, resist images) of the measurement pattern on the developed wafer is measured by an appropriate measuring device.
Then, the positioning accuracy of the wafer is determined based on the difference between the measured value and the movement amount.

As the above-mentioned measuring device, an SEM (scanning electron microscope) or the like can be used. For example, an alignment sensor provided in an exposure device (for example, an alignment detection system (for example, an alignment detection system used for wafer alignment)) can be used. A so-called LSA (Laser Step Alignment) that detects a diffracted light by scanning the laser beam and the resist image relatively.
so-called FIA (Field Image Alignment), which forms an image of an alignment mark or an alignment mark on an image sensor.
t)) may be used.

In the case of a scanning type exposure apparatus, the positioning accuracy of the reticle stage (reticle) can be obtained by the same method as the measurement of the positioning control accuracy of the wafer stage. However, in this case, contrary to the above, the reticle is moved by a predetermined amount while the wafer is kept still.

[0011]

However, in the above-mentioned conventional measuring method, the difference between the movement amount, which is the measured value of the length measuring device (for example, a laser interferometer, etc.), and the measured value of the distance between the respective transferred images. To obtain the amount of displacement directly from
When the displacement amount is small, there is a disadvantage that the displacement cannot be detected due to the detection limit of a measuring device (for example, the above-described alignment detection system) that measures the distance between the transferred images. Further, since the resolution of the laser interferometer for measuring the moving amount of the wafer stage (wafer) is about 0.5 nm, the above conventional measuring method is considered in consideration of the total overlay error allowed for a future projection exposure apparatus. Then, it is difficult to measure the position control accuracy with the required accuracy.

The present invention has been made under such circumstances, and a first object of the present invention is to provide a mask which can be suitably used for measuring the position control accuracy of a mask stage or a substrate stage.

A second object of the present invention is to provide a position control accuracy measuring method capable of accurately measuring the position control accuracy of a mask stage (mask) or a substrate stage (substrate).

[0014] A third object of the present invention is to provide an exposure method capable of realizing highly accurate exposure.

It is a fourth object of the present invention to provide a device manufacturing method capable of improving the productivity of a highly integrated device.

[0016]

According to the first aspect of the present invention, there is provided a first pattern (TP1) and a second pattern in which the shape of an overlapping portion becomes constant regardless of the overlapping position when transferred in an overlapping manner. (TP2) and the first pattern having the same mutual positional relationship as the positional relationship between the first pattern and the second pattern. The second set of patterns including the third pattern (TP3) and the fourth pattern (TP4), which change depending on the overlapping position, do not overlap each other.
The mask substrate (4) formed on the pattern surface (PA)
2) A mask provided with 2).

Consider, for example, the case where the accuracy of position control of a substrate stage of an exposure apparatus is measured using this mask. In this case, at least two exposures are performed with the mask stationary. For example, at the time of the first exposure, for example, by performing the exposure while limiting the illumination area so that only the first pattern and the third pattern are irradiated with the illumination light, the substrate positioned at a predetermined position is exposed. The first pattern and the third pattern are respectively transferred to the predetermined area. Then
After the substrate stage that holds the substrate is moved in a distance and a direction corresponding to the positional relationship between the first pattern and the second pattern, for example, the illumination area is illuminated so that only the second pattern and the fourth pattern are irradiated with illumination light. Is performed, the second pattern is superimposed on the transfer image of the first pattern, and the fourth pattern is transferred over the transfer image of the third pattern. .

As a result, the overlapped portions of the transferred images of the first pattern and the second pattern include a reference mark image (including a latent image, a resist image, etc .; hereinafter, a "reference mark image").
Is formed, and an image of a mark to be compared (hereinafter, referred to as a “comparison mark image”) is formed at an overlapping portion between the transferred images of the third pattern and the fourth pattern.

Here, the reference mark image has a fixed shape independent of the relative overlapping position of the first and second patterns, and the comparative mark image has a relative overlapping position of the third and fourth patterns. It has a shape that changes depending on the position. Therefore, from the difference in the shapes of the reference mark image and the comparison mark image, information (position shift amount and position shift direction) of the positioning accuracy (a type of position control accuracy) of the substrate stage can be obtained.

As an example, when the patterns are accurately superimposed according to the positional relationship, the first to fourth patterns are formed on the pattern surface of the mask so that the reference mark image and the comparison mark image have the same shape. Consider the case where it is formed. In this case, if the lengths of the corresponding portions of the reference mark image and the comparison mark image formed on the substrate by the two exposures are the same, the patterns can be accurately overlapped according to the positional relationship. Indicates that the position control of the substrate stage (substrate) has been correctly performed. On the other hand, if the lengths of the corresponding portions of the reference mark image and the comparison mark image are different, a shift occurs in the pattern overlapping position,
Information on the position control accuracy of the substrate stage can be obtained based on the difference in length between corresponding portions of the reference mark image and the comparison mark image.

In particular, in the case of a scanning type exposure apparatus, a mask is formed by the same method as that for measuring the information (position shift amount and direction) of the positioning control accuracy (a type of position control accuracy) of the substrate stage. Information (position shift amount and position shift direction) of the positioning accuracy (a type of position control accuracy) of the stage (mask) can be obtained. In this case, however, the mask is moved by a predetermined amount while the substrate is kept stationary, and the setting of the illumination area is the first.
The same settings are made for the second exposure and the second exposure.

In this case, the measurement of the lengths of the reference mark image and the comparison mark image may be performed on the latent image formed on the substrate without developing the substrate, or may be performed on the reference mark image and the comparison mark image. After developing the substrate on which the comparative mark image is formed, the process may be performed on a resist image formed on the substrate or an image (etched image) obtained by etching the substrate on which the resist image is formed. .

The lengths of the reference mark image and the comparison mark image may be measured by using, for example, an alignment detection system (LSA system, FIA system) provided in the exposure apparatus.

In this case, various patterns can be considered as the first to fourth patterns.
The first pattern is a pattern including at least one line pattern extending in a first direction, and the second pattern is formed at an angle θ1 (0 <θ1 <180) with respect to the first direction. °) is a pattern including at least one line pattern extending in the second direction, wherein the third pattern has a linear first portion extending in the first direction and a linear first portion extending in the second direction. The second pattern is a chevron-shaped pattern as a whole, and the fourth pattern includes a linear first portion extending in the first direction and the second portion.
The second pattern may have a linear second portion extending in the direction, and may be a chevron-shaped pattern that is opposite to the third pattern as a whole.

Here, the "angle" means a magnitude of an angle formed by the directions, and is a concept that does not include the angle direction (positive or negative). In this specification, as such a concept,
The vocabulary "angle" is used.

In this specification, “Yamagata” means
A shape composed of two linear portions extending in different directions, including a U-shape, a V-shape, and shapes deformed (eg, rotated, scaled (whole and part), etc.) It is. Further, the lengths of the first portion and the second portion do not necessarily have to be the same.

In the mask according to the first aspect, as in the mask according to the third aspect, the first pattern is a pattern including at least one line pattern extending in a third direction, and the second pattern is a second pattern. Is a pattern including at least one line pattern extending in a fourth direction forming an angle θ2 (0 <θ2 <180 °) with respect to the third direction, wherein the third pattern is formed in the third direction and the third direction. A pattern including at least one line pattern extending in a fifth direction at an angle θ2 / 2 with respect to the four directions, wherein the fourth pattern has an angle θ with respect to the fifth direction.
2 having a linear first portion extending in a sixth direction and a linear second portion extending in a seventh direction different from the sixth direction at an angle θ2 with respect to the fifth direction. Pattern.

In each of the masks according to the first to third aspects, the line widths of the first to fourth patterns may be various. However, as in the mask according to the fourth aspect,
The line widths of the first to fourth patterns may be equal. As in the mask according to claim 5, the line widths of the first to third patterns are equal and the line width of the fourth pattern is equal to the line width of the fourth pattern. It may be different from the line width of the first to third patterns,
Further, as in the mask according to claim 6, the first and second patterns may have a first line width, and the third and fourth patterns may have a second line width.

According to a seventh aspect of the present invention, there is provided a position control accuracy measuring method for measuring the accuracy of position control using the mask ( _RT ) according to any one of the first to sixth aspects. A first exposure step of transferring the first pattern (TP1) and the third pattern (TP3) on the mask onto the substrate (W);
Moving one of the mask and the substrate in a predetermined direction by a distance corresponding to a positional relationship between the first pattern and the second pattern (TP2); and a step of moving the first pattern and the substrate formed on the substrate. A second exposure step in which the second pattern and the fourth pattern (TP4) on the mask are respectively transferred onto the transfer image of the third pattern so as to overlap with each other;
A reference mark image (SM1) formed on an overlapping portion of a transfer image of the first pattern and the second pattern on the substrate
And a measurement step of measuring the length of the comparison mark image (HM1) formed at the overlapping portion of the transfer images of the third pattern and the fourth pattern, respectively; and the measurement of the reference mark image and the comparison mark image Calculating a position control accuracy based on the length.

According to this, first, after the first pattern and the third pattern on the mask are transferred onto the substrate in the first exposure step, any one of the mask and the substrate is transferred to the second pattern in the moving step. It moves in the distance and direction according to the positional relationship with the pattern. Then, when the movement of either the mask or the substrate is completed, in the second exposure step, the second pattern and the fourth pattern on the mask are transferred onto the substrate. As a result, the second pattern is transferred to be superimposed on the transfer image of the first pattern, and the fourth pattern is transferred to be superimposed on the transfer image of the third pattern. In an actual exposure apparatus, the movement of the mask is performed by moving the mask stage that holds the mask, and the movement of the substrate is performed by moving the substrate stage that holds the substrate.

As a result of the transfer of the second pattern and the fourth pattern on the mask, a reference mark image (eg, a latent image) is formed at an overlapping portion between the transferred images of the first pattern and the second pattern on the substrate. The comparative mark image is formed at the overlapping portion between the transferred images of the fourth pattern and the third pattern. In the measurement step, the lengths of the reference mark image and the comparison mark image are measured, and in the calculation step, the accuracy of the position control is calculated based on the measurement results. In this case, the reference mark image has a fixed shape that does not depend on the relative overlapping position of the first pattern and the second pattern.
It has a shape that changes depending on the relative overlapping position of the third pattern and the fourth pattern. Therefore, by comparing the lengths of the corresponding portions of the reference mark image and the comparison mark image, the shift information of the overlapping position can be obtained. That is, instead of measuring the distance between the transferred images as in the conventional case, the length of each of the corresponding portions of the reference mark image and the comparison mark image is measured to obtain a mask (mask stage).
Alternatively, the position control accuracy of the substrate (substrate stage) is determined.

That is, as an example, when patterns are accurately superimposed according to the positional relationship,
Consider a case where the first to fourth patterns are formed on the pattern surface of the mask such that the reference mark image and the comparison mark image have the same shape. In this case, if the lengths of the corresponding portions of the reference mark image and the comparison mark image formed on the substrate by the second exposure are the same, the patterns can be accurately overlapped according to the positional relationship. Has been done,
This indicates that the position of the mask (mask stage) or the substrate (substrate stage) has been correctly controlled.

On the other hand, if the lengths of the corresponding portions of the reference mark image and the comparison mark image are different from each other, there is a shift in the overlapping position of the pattern, and the difference in the lengths of the corresponding portions of the respective mark images. From the position of overlap, ie, mask (mask stage) or substrate (substrate stage)
Information on the position control accuracy can be obtained.

In this case, as in the position control accuracy measuring method according to claim 8, in the calculating step, at least one of the positioning accuracy of any of the mask and the substrate and the pattern overlay accuracy is calculated. It is good to do.

In the position control accuracy measuring method according to the seventh aspect, in the first exposure step and the second exposure step, as in the position control accuracy measurement method according to the ninth aspect, the mask and the substrate are separated. The exposure may be performed in a stationary state, or the exposure may be performed while moving the mask and the substrate in synchronization, as in the position control accuracy measurement method according to the tenth aspect.

In the position control accuracy measuring method according to the tenth aspect, as in the position control accuracy measuring method according to the eleventh aspect, in the calculating step, the synchronization accuracy between the mask and the substrate may be calculated. good.

According to a twelfth aspect of the present invention, there is provided an exposure method for transferring a mask pattern onto a substrate.
Measuring the position control accuracy by the position control accuracy measurement method according to any one of 11; performing position control of at least one of the mask and the substrate in consideration of the measured position control accuracy, Transferring the pattern of the mask onto the substrate.

According to this, the position control of at least one of the mask and the substrate is performed so that the optimum transfer is performed in consideration of the position control accuracy measured by each of the position control accuracy measurement methods according to claims 7 to 11. Then, the pattern of the mask is transferred onto the substrate. Therefore, the fine pattern can be transferred onto the substrate with high accuracy while maintaining the positional relationship between the mask pattern and the substrate in a desired relationship.

According to a thirteenth aspect of the present invention, there is provided a device manufacturing method including a lithography step, wherein the lithography step uses the exposure method according to the twelfth aspect.

According to this, in the lithography process, a fine pattern can be accurately transferred onto the substrate by the exposure method according to the twelfth aspect, and as a result, the productivity (yield of a highly integrated device) can be reduced. Included) can be improved.

[0041]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.
19 will be described.

FIG. 1 shows an exposure apparatus 100 according to an embodiment suitable for carrying out the position control accuracy measuring method and the exposure method according to the present invention. The exposure apparatus 100 is a step-and-scan projection exposure apparatus.

The exposure apparatus 100 includes an illumination system IOP and a reticle stage R for holding a reticle R as a mask.
ST (mask stage), a projection optical system PL for projecting an image of a pattern formed on a reticle R onto a wafer W as a substrate coated with a photosensitive agent (photoresist), a two-dimensional plane holding the wafer W ( XY moving in the XY plane)
A stage 20 (substrate stage), a drive system 22 for driving the XY stage 20, and a control system for these components are provided. This control system is mainly configured by a main control device 28 that integrally controls the entire device.

The illumination system IOP includes a light source such as a KrF excimer laser or an ArF excimer laser, a fly-eye lens or a rod-type (internal reflection type) integrator as an optical integrator or a homogenizer, a relay lens, a condenser lens, and a reticle blind. (All are not shown). In the illumination system IOP, a rectangular slit-shaped illumination area that is elongated in the X-axis direction in the visual field of the projection optical system PL defined by a reticle blind on a reticle R on which a circuit pattern or the like is drawn is substantially irradiated with illumination light IL. Illuminate with uniform illuminance.

The reticle stage RST includes an illumination system I
It is located below the OP in FIG. A reticle R is suction-held on the reticle stage RST via a vacuum chuck or the like (not shown). The reticle stage RST is used to position the reticle R for the purpose of positioning the reticle R in the Y-axis direction (the left-right direction on the paper surface in FIG. 1), the X-axis direction (a direction perpendicular to the paper surface in FIG.
It can be driven minutely in the direction of rotation about the axis) and can be driven in a predetermined scanning direction (here, the Y-axis direction) at a designated scanning speed.

A movable mirror 15 for reflecting a laser beam from a reticle laser interferometer (hereinafter referred to as a "reticle interferometer") 21 is fixed on reticle stage RST. The reticle interferometer 21 constantly detects, for example, with a resolution of 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. Although a reticle Y interferometer and a reticle X interferometer are provided, these are typically shown as a movable mirror 15 and a reticle interferometer 21 in FIG. Here, reticle Y interferometer and reticle X
One of the interferometers, for example, a reticle Y interferometer, has two measurement axes.
It is a two-axis interferometer having an axis, and in addition to the Y position of the reticle stage RST,
The θz direction can also 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 controls the reticle stage RST via the drive system 29 based on the position information of the reticle stage RST.
Drive.

Thus, reticle stage RST
The reticle R can be positioned (reticle alignment) with the center of the pattern of the reticle R (reticle center) substantially coincident with the optical axis AXp of the projection optical system PL. FIG. 1 shows a state in which this reticle alignment has been performed.

The projection optical system PL is arranged below the reticle stage RST in FIG. 1 so that the direction of the optical axis AXp is the Z-axis direction orthogonal to the XY plane. The projection optical system PL is a reduction system that is telecentric on both sides, and has a common optical axis A in the Z-axis direction.
A refractive optical system including a plurality of lens elements having X is used. Specific plural lenses among the lens elements are controlled by an imaging characteristic correction controller (not shown) based on a command from main controller 28, and optical characteristics (including imaging characteristics) of projection optical system PL, for example, magnification. , Distortion, coma aberration, field curvature and the like can be adjusted.

The XY stage 20 is actually a Y stage that moves on a base (not shown) in the Y axis direction.
An X stage is configured to move on the stage in the X-axis direction, and these are shown as XY stages 20 in FIG. A wafer table 18 is mounted on the XY stage 20, and a wafer W is held on the wafer table 18 via a wafer holder (not shown) by vacuum suction or the like.

The XY stage 20 not only moves in the scanning direction (Y-axis direction), but also allows a plurality of shot areas on the wafer W to be positioned in a projection area in a visual field conjugate to the illumination area. , And can also be moved in a non-scanning direction (X-axis direction) orthogonal to the scanning direction. Then, a step-and-scan operation of repeating an operation of scanning (scanning) exposing each shot area on the wafer W and an operation of moving to a scan start position (acceleration start position) for exposure of the next shot is performed.

The wafer table 18 minutely drives the wafer holder for holding the wafer W in the Z-axis direction and the tilt direction with respect to the XY plane. This wafer table 1
8 is provided with a movable mirror 24, which projects a laser beam on the movable mirror 24 and receives the reflected light, thereby measuring the position of the wafer table 18 in the XY plane. A total 26 is provided to face the reflecting surface of the movable mirror 24. Actually, the moving mirror is provided with an X moving mirror having a reflecting surface orthogonal to the X axis and a Y moving mirror having a reflecting surface orthogonal to the Y axis. 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 representatively the moving mirror 24, the laser interferometer 2
6 is shown. The X laser interferometer and Y laser
A laser interferometer is a multi-axis interferometer having a plurality of measuring axes,
In addition to the X and Y positions of the wafer table 18, rotation (yaw (θz rotation about the Z axis)), pitching (X
Rotation (θx rotation around the axis) and rolling (θy rotation around the Y axis) can also be measured. Therefore, in the following description, it is assumed that the laser interferometer 26 measures the positions of the wafer table 18 in the five degrees of freedom directions of X, Y, θz, θy, and θx.

The measured value of the laser interferometer 26 is
And the main controller 28 controls the laser interferometer 26
The position of the wafer table 18 is controlled by driving the XY stage 20 via the drive system 22 while monitoring the measured values of the above.

The Z direction position and the tilt amount of the surface of the wafer W are
For example, the measurement is performed by a focus sensor AFS including an oblique incidence type multipoint focal position detection system having a light transmitting system 50a and a light receiving system 50b disclosed in Japanese Patent Application Laid-Open No. 6-283403. The measurement value of the focus sensor AFS is also supplied to the main controller 28,
The main controller 28 controls the position and inclination of the wafer W in the optical axis direction of the projection optical system PL by slightly driving the wafer table 18 via the drive system 22 based on the measurement value of the focus sensor AFS. Has become.

That is, the position and orientation of the wafer W in the directions of five degrees of freedom of X, Y, Z, θx and θy are controlled via the wafer table 18 in this manner. Note that the remaining error of θz (yawing) is calculated based on the wafer table 18 measured by the laser interferometer 26.
Is corrected by rotating at least one of the reticle stage RST and the wafer table 18 based on the yawing information.

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

Further, in the present embodiment, an off-axis type alignment detection system AS as a mark detection system for detecting an alignment mark formed on the wafer W is provided on a side surface of the projection optical system PL. This alignment detection system AS has an alignment sensor called an LSA system and an FIA system, and can measure the position of the reference mark on the reference plate FP and the alignment mark on the wafer in the X and Y two-dimensional directions. It is.

Here, the LSA system is the most versatile sensor that irradiates a mark with a laser beam and measures the position of the mark by using the diffracted and scattered light. Have been. The FIA system is a sensor that illuminates a mark with broadband (broadband) light such as a halogen lamp and measures the mark position by processing the mark image, and is used effectively for an asymmetric mark on an aluminum layer or a wafer surface. You.

The alignment control device 16 A / D converts the information DS from the alignment detection system AS, and further performs arithmetic processing on the digitized signal to detect a mark position. This detection result is supplied from the alignment control device 16 to the main control device 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, JP-A-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 on reticle stage RST (both not shown) and a mark on reference plate FP. An alignment microscope is provided. The detection signals of these reticle alignment microscopes are supplied to the main controller 28 via the alignment controller 16.

Next, an example of a reticle used for measuring the position control accuracy of the wafer W (XY stage 20) and reticle R (reticle stage RST) according to the present invention will be described.

FIG. 2 shows an XY stage 20 and a reticle.
Reticle used for measuring position control accuracy of stage RST
Kuru R_TAn example is shown. FIG. 2 shows a reticle
R_TViewed from the pattern surface side (the lower surface side in FIG. 1).
It is a top view. This reticle R _TIs an almost square cell
In the center of a glass substrate 42 as a
PA is provided, and the pattern area PA is described later.
A measurement pattern is arranged. Also, the pattern area
Center of PA, ie, reticle R_TThe center of the (reticle
On both sides in the X-axis direction of the pattern area PA passing through
A pair of reticle alignment marks RM1 and RM2 are formed
Has been established.

Here, a description will be given of a measurement pattern arranged in the pattern area PA of the reticle _RT in the present embodiment.

In the pattern area PA, for example, a measurement pattern RP1 as shown in an enlarged manner in FIG. 3 is arranged.

The measurement pattern RP1 is a pattern for measuring the position control accuracy of the XY stage 20 and the reticle stage RST when the reticle stage RST is moved in the X-axis direction, and includes eight types of patterns TP1 to TP8. It is configured. The pattern TP1 (first pattern) is
Clockwise angle θ / 2 (0 <θ <18) with respect to the X axis
0 °), and extends in the first direction.
The pattern TP2 (second pattern) is the pattern TP
1 and a line pattern extending in the second direction at an angle θ / 2 counterclockwise in the drawing with respect to the X axis. In this case, the pattern TP2 is disposed below the sheet of the pattern TP1 (−X direction), and the center of the pattern TP1 and the center of the pattern TP2 are separated by ΔRX in the X-axis direction.

The pattern TP3 (third pattern) has a linear first portion extending in the first direction and a linear second portion extending in the second direction, and is a mountain-shaped pattern as a whole. The pattern TP4 (fourth pattern) is a pattern that forms a pair with the pattern TP3, and has a linear first portion extending in the first direction and a linear second portion extending in the second direction. It is a chevron-shaped pattern that is opposite to the pattern TP3 as a whole. In this case, the pattern TP4
Are arranged below the plane of the pattern TP3 (−X direction), and the center of the pattern TP3 and the pattern TP3
4 is separated by ΔRX in the X-axis direction.

That is, the positional relationship between the patterns TP3 and TP4 (the second set of patterns) is the same as the positional relationship between the patterns TP1 and TP2 (the first set of patterns).

The patterns TP5, TP6, TP7,
TP8 is the pattern TP1, TP2, TP, respectively.
3, TP4 is rotated 90 degrees counterclockwise in the plane of the paper.

That is, the pattern TP5 is a line pattern extending in the eighth direction (a direction making an angle θ / 2 clockwise with respect to the Y axis) by rotating the first direction by 90 degrees clockwise. Is a pattern that forms a pair with the pattern TP5, and forms a direction that forms an angle θ / 2 counterclockwise with respect to the Y axis, that is, a direction that forms an angle of 90 degrees with the second direction (hereinafter, for convenience, “ninth Direction)
This is a line pattern extending to. The pattern TP6 is arranged below the pattern TP5 in the drawing (-X direction), and the center of the pattern TP5 and the center of the pattern TP6 are separated by ΔRX in the X-axis direction.

The pattern TP7 has a first linear portion extending in the eighth direction and a second linear portion extending in the ninth direction, and is a chevron-shaped pattern as a whole. The pattern TP8 is a pattern that forms a pair with the pattern TP7, and has a linear first portion extending in the eighth direction and a linear second portion extending in the ninth direction. It is a mountain-shaped pattern in the opposite direction. In this case, the pattern TP8 is arranged below (in the −X direction) the plane of the pattern TP7, and the center of the pattern TP7 and the center of the pattern TP8 are separated by ΔRX in the X-axis direction. That is, the positional relationship between the pattern TP7 and the pattern TP8 is the same as the positional relationship between the pattern TP5 and the pattern TP6.

The patterns TP1 to TP4 are patterns for detecting a displacement in the Y-axis direction, and the patterns TP5 to TP8 are patterns for detecting a displacement in the X-axis direction. In the present embodiment, as an example, the patterns TP1 to TP8 have the same line width.

In the pattern area PA of the reticle _RT , the area where the measurement pattern RP1 is not arranged is a light-shielding pattern. That is, in the present embodiment, a part of the pattern area PA becomes a light transmitting portion, and the patterns TP1 to TP8 are formed as light shielding portions in the light transmitting portion.

Next, a brief description will be given of an operation flow when the reticle pattern is transferred onto the wafer W by the exposure apparatus 100 of the present embodiment and the positioning accuracy (a type of position control accuracy) of the XY stage 20 is measured. I do.

First, wafer W is loaded onto wafer table 18 by a wafer loader (not shown), and reticle _RT is loaded onto reticle stage RST by a reticle loader (not shown).

Main controller 28 determines that the center of a pair of reference marks (not shown) formed on the surface of reference plate FP provided on wafer table 18 substantially coincides with the optical axis of projection optical system PL. Thus, the reference plate FP is moved. This movement is performed by moving the XY stage 20 via the drive system 22 while monitoring the measurement result of the laser interferometer 26 by the main controller 28. Next, the main controller 28
Adjusts the position of reticle stage RST via drive system 29 such that the center (reticle center) of reticle _RT substantially matches the optical axis of projection optical system PL. At this time, for example, the relative position between the reticle alignment marks RM1 and RM2 and the corresponding reference mark is detected by the reticle alignment microscope (not shown) via the projection optical system PL.

Main controller 28 controls reticle alignment marks RM1 and RM2 based on the result of detection of the relative position detected by the reticle alignment microscope.
And reticle stage R via drive system 29 such that the relative position error with respect to the reference mark is minimized.
Adjust the position of ST in the XY plane. Thus, the reticle R _T center (reticle center) of an orthogonal coordinate system defined by the reticle R _T rotational angle even laser interferometer 26 measurement axes of with exact match substantially with the optical axis of the projection optical system PL Exactly coincide with the axes. That is, the reticle alignment is completed.

Next, the main controller 28 controls the illumination system IO
By adjusting the size and position of the opening of the reticle blind (not shown) in P, the irradiation area of the illumination light IL is adjusted to the reticle _RT.
The size and the position of the opening of the reticle blind (not shown) in the illumination system IOP are adjusted so as to coincide with the area where the measurement pattern RP1 is arranged. At the same time,
In the present embodiment, the main controller 28 moves the XY stage 20 via the drive system 22 while monitoring the measurement result of the laser interferometer 26. In this embodiment, the wafer has a surface coated with a positive resist as a photosensitive agent. W is moved to a position below the projection optical system PL. In the case of the present embodiment, since the area other than the area where the measurement pattern RP1 of the reticle _RT is arranged is a light-shielding pattern, the illumination area is set to coincide with the pattern area when setting the illumination area. You may do it.

In this state, main controller 28 performs the first time
Perform exposure. Here, the positioning precision of the XY stage 20 is
During exposure, the reticle is
Le R _TAnd wafer W, that is, reticle stage RST
The XY stage 20 remains stationary. This
R, reticle R_TIs projected through the projection optical system PL.
Reduced transfer to a photoresist layer on wafer W (first
Exposure step). At this time, the normal exposure dose (that is,
Exposure is performed with an appropriate amount according to the sensitivity characteristics of the resist). This
As a result, the resist layer on the wafer W is indicated by a dotted line in FIG.
Images of patterns TP1 to TP8 are transferred
You. Here, the transfer images TP1W to TP8W are respectively
It corresponds to the transfer image of the patterns TP1 to TP8.

Next, main controller 28 sets pattern TP
The XY stage 20 is moved by a predetermined amount in a predetermined direction based on the positional relationship between the XY stage 1 and the pattern TP2 (moving step). In the present embodiment, since the center of the pattern TP1 and the center of the pattern TP2 are separated by ΔRX in the X-axis direction, if the magnification of the projection optical system PL is, for example, １ ／, the distance of ΔRX / 4 Only -XY stage 2 in X direction
Move 0. At this time, main controller 28 moves XY stage 20 via drive system 22 while monitoring the measurement value of laser interferometer 26.

As described above, the target position (ΔRX / 4
When the positioning of the wafer W to the position moved only in the −X direction) is completed, the main controller 28 performs the same exposure (second exposure) as described above (second exposure step). At this time, exposure is performed at a normal exposure dose. Thereby, the images of the patterns TP1 to TP8 indicated by the solid lines in FIG. 4 are transferred. In this case, the patterns TP1, TP3, TP5, which have been transferred to the resist layer on the wafer W in the first exposure,
Patterns TP2, TP4, TP6, TP on the latent image of TP7
8 are transferred to overlapping positions. That is,
An image of the pattern TP2 is provided on the transfer image TP1W, and a transfer image TP3 is provided.
The image of the pattern TP4 is transferred to W, the image of the pattern TP6 is transferred to the transfer image TP5W, and the image of the pattern TP8 is transferred to the transfer image TP7W.

When the second exposure is completed, the wafer W is unloaded from the wafer table 18 by a wafer loader (not shown) in accordance with an instruction from the main controller 28, and then the wafer transfer system (not shown) The exposure apparatus 1
Coater (not shown) connected in-line to 00
Conveyed to developer.

The wafer W is developed in the coater / developer. Upon completion of the development, the wafer W
As an example, as shown in FIG. 5, transfer images TP1W and T
The reference mark image SM1 is placed on the overlapping portion of P2W,
The comparative mark image HM1 is located at the overlapping portion of 3W and TP4W, and the reference mark image SM is located at the overlapping portion of the transferred images TP5W and TP6W.
2, a comparison mark image HM2 is formed at the overlapping portion of the transfer images TP7W and TP8W. The reference mark image SM1 and the comparison mark image HM1 are mark images for detecting a displacement in the Y-axis direction, and the reference mark image SM2 and the comparison mark image HM2 are for detecting a displacement in the X-axis direction. It is a mark image.

Here, the fact that the shape of the reference mark image is constant regardless of the overlapping position will be described as an example with reference to FIG. FIG. 6A shows the wafer W
Transfer image T when the amount of movement in the −X direction is ΔRX / 4
FIG. 6B shows an overlapping state of the transfer images TP1W and TP2W when the amount of movement of the wafer W in the −X direction is smaller than ΔRX / 4 by ΔX1. FIG. 6C shows the -X of the wafer W.
The state where the transfer images TP1W and TP2W overlap each other when the amount of movement in the direction is greater than ΔRX / 4 by ΔX2 is shown. Since the transfer images TP1W and TP2W are linear images having the same line width and extending in different directions, as shown in FIG. 6, if the transfer amount of the wafer W is different, the transfer images TP1W and TP2W overlap. (The shape connecting the intersections is the shape of the reference mark image) is different, but the distance between the intersections does not change. Therefore, the shape of the reference mark image does not depend on the overlapping position, and has the same shape in any case.

On the other hand, how the comparison mark image changes depending on the overlapping position will be described with reference to FIG. 7 as an example. FIG. 7A shows an overlapping state of the transferred images TP7W and TP8W when the amount of movement of the wafer W in the −X direction is ΔRX / 4, and FIG. X
The transfer image TP7W and the transfer image TP8W overlap when the movement amount in the direction is smaller than ΔRX / 4 by ΔX3. FIG. 7C shows that the movement amount of the wafer W in the −X direction is ΔRX. Transfer image T when ΔX4 is larger than / 4
The overlapping state of P7W and TP8W is shown. Here, the transfer image TP7W and the transfer image TP8W are chevron images opposite to each other. Therefore, if the movement amount of the wafer W is different as shown in FIG.
The number of intersections when P8W overlaps (the shape connecting the intersections is the shape of the comparison mark image) and the distance between the intersections change. Therefore, the shape of the comparison mark image changes depending on the overlapping position. Note that the shape of the comparative mark image is not limited to a square (a rhombus or a parallelogram) depending on the value of the angle θ and the amount and direction of displacement of the overlapping position.
As shown in (C), a part of the quadrangle may be a missing polygon. However, in the following description, in the case where the shape of the comparison mark image is a polygon in which a part of a quadrangle is missing, it is assumed that there is no missing for convenience. This is because such treatment does not affect the measurement result.

For the above-mentioned reason, by comparing the shape of the reference mark image and the shape of the comparison mark image, the shift information (position shift amount and position shift direction) of the pattern overlapping position is obtained.
Can be requested. For example, if the patterns are arranged in the pattern area PA in a positional relationship such that the reference mark image and the comparison mark image have the same shape when the patterns are accurately superimposed, the comparison with the reference mark image is performed. The lengths of the corresponding portions of the mark images are measured, and if the measured values are the same, this indicates that the patterns have been correctly overlapped. On the other hand, if the measured values are different, a shift occurs in the pattern overlap position, and the shift information of the pattern overlap position can be obtained based on the difference between the lengths of both mark images.

In this embodiment, when the patterns are accurately superimposed, each of the patterns TP1 to TP has a positional relationship such that the reference mark image and the comparison mark image have the same shape.
4, and TP5 to TP8 are arranged in the pattern area PA, so that the longer diagonal length LS1 of the reference mark image SM1, the longer diagonal length LH1 of the comparison mark image HM1, and the reference mark image SM2 Longer diagonal length LS2, longer diagonal length L of comparison mark image HM2
From the measured value of H2, it is possible to obtain information on the displacement of the pattern overlapping position when the XY stage 20 is moved in the X-axis direction. In this embodiment, the reference mark image SM1 has a longer rectangular diagonal line oriented in the X-axis direction, and the reference mark image SM2 has a longer rectangular diagonal line Y.
Axial. Then, the reference mark images SM1, S
In each of M2, a pair of diagonal angles is θ. The comparative mark image HM1 has a longer rectangular diagonal line oriented in the X-axis direction, and the comparative mark image HM2 has a longer rectangular diagonal line oriented in the Y-axis direction. Further, each of the comparison mark images HM1 and HM2 has a pair of diagonal angles θ, like the reference mark images SM1 and SM2.

Therefore, the length measurement of the reference mark image and the comparison mark image formed on the wafer W is performed as follows (measurement step).

In the present embodiment, as an example, since the lengths of the reference mark image and the comparison mark image are measured using the alignment detection system AS, the main controller 28 receives the notification of the completion of the development from the coater / developer. The wafer W is transferred into the exposure apparatus by instructing a wafer transfer system (not shown), and the transferred wafer W is loaded on the wafer table 18 again by the wafer loader.

The main controller 28 converts the reference mark image SM1 formed on the wafer W into an alignment detection system A
Moving directly below S, the length LS1 of the longer diagonal line of the reference mark image SM1 is measured using, for example, an LSA system. Note that a method of measuring the line length of a wedge mark (a kind of diamond mark) using an LSA-based sensor is widely known as an SMP measurement technique, and thus the details of the measurement method are omitted.

Similarly, main controller 28 determines the length LS2 of the longer diagonal of other reference mark image SM2 and the length LH of the longer diagonal of comparison mark images HM1 and HM2.
1 and LH2 are measured.

Next, a method of calculating the positioning accuracy of the XY stage 20 based on the lengths of the reference mark image and the comparison mark image measured as described above will be described (calculation step).

First, the main controller 28 controls the XY stage 2
As described above, the displacement amount of the XY stage 20 (wafer W) in the X-axis direction when 0 is moved in the −X direction by ΔRX / 4 is calculated. The displacement amount in the X-axis direction is determined by the length LS2 of the reference mark image SM2 and the length LH of the comparison mark image HM2.
It is calculated using the measured value of 2.

Here, the main controller 28 controls the LS2 and L
The measured values of H2 are compared, and if they are the same value, when the XY stage 20 is moved in the −X direction by ΔRX / 4 in the moving step, the amount of movement of the wafer W in the −X direction is also Δ.
RX / 4, displacement in the X-axis direction (positioning error)
Judge that there is no.

On the other hand, the main controller 28 controls LS2 and LH2.
Are different from each other, it is determined that the amount of movement of the wafer W in the −X direction is not ΔRX / 4 and there is a displacement in the X axis direction. Here, a method of obtaining positional displacement information in the X-axis direction will be described, where the difference between the length LS2 of the reference mark image and the length LH2 of the comparison mark image is ΔSH2. When the comparative mark image is a polygon in which a part of a quadrangle is missing, it is possible to handle the comparative mark image in the same manner as a quadrangle by assuming that there is virtually no missing part.

Assuming that the length of the shorter diagonal line of the reference mark image SM2 is DS2, DS2 and LS2 are represented by the following (1).
It is in the relationship of the formula.

DS2 = LS2 × tan (θ / 2) (1)

Assuming that the length of the shorter diagonal line of the comparative mark image HM2 is DH2, DH2 and LH2 have the following equation (2).

DH2 = LH2 × tan (θ / 2) (2)

Here, assuming that the difference between DS2 and DH2 is ΔD2, ΔSH2 and ΔD2 which are the differences between LS2 and LH2.
Is expressed by the following equation (3) from the above equations (1) and (2).

ΔD2 = ΔSH2 × tan (θ / 2) (3)

This ΔD2 has a value equivalent to twice the distance between the center of the transferred image TP7W and the center of the transferred image TP8W. Therefore, if the amount of displacement in the X-axis direction is ΔX5,
The relationship between ΔX5 and ΔD2 is shown by the following equation (4).

ΔD2 = ΔX5 × 2 (4)

Therefore, from the above equations (3) and (4),
The following equation (5) is obtained.

ΔX5 = ΔSH2 × tan (θ / 2) ÷ 2 (5)

The main controller 28 calculates the difference between the length of the longer diagonal of the reference mark image SM2 and the length of the longer diagonal of the comparison mark image HM2. Then, the amount of displacement in the X-axis direction is obtained based on

Further, main controller 28 determines the direction of displacement (+ X direction or −X direction) from the magnitude relationship between the length of the reference mark image and the length of the comparison mark image. For example, when the length LS2 of the reference mark image is larger than the length LH2 of the comparison mark image, as shown in FIG. 8A, the wafer W (XY stage 20) moves in the + X direction from the expected position. When the length LH2 of the comparison mark image is longer than the length LS2 of the reference mark image, the wafer W (XY stage 20) is moved to the predetermined position, as shown in FIG. More shifted in the -X direction. In other words, the shape of the comparative mark image differs depending on the direction of the positional shift even if the positional shift amount is the same.

Therefore, when the position of the XY stage 20 is controlled so as to move by ΔRX / 4 in the −X direction, the main controller 28 controls the length LS2 of the reference mark image SM2 and the length LH2 of the comparison mark image HM2. However, if the relationship is as shown in FIG. 8A, for example, the movement amount of the wafer W is (ΔR
X / 4−ΔX5). For example, if the relationship is as shown in FIG. 8B, the moving amount of the wafer W is (ΔRX / 4).
+ ΔX5).

Next, main controller 28 controls XY stage 2
As described above, the displacement amount of the XY stage 20 (wafer W) in the Y-axis direction when 0 is moved in the −X direction by ΔRX / 4 is calculated. The amount of displacement in the Y-axis direction is determined by the length LS1 of the reference mark image SM1 and the length LH of the comparison mark image HM1.
It is calculated using the measurement value of 1. In the moving step, X
Since the Y stage 20 has not moved in the Y-axis direction, the wafer W should not move in the Y-axis direction. However, if the positioning accuracy of the XY stage 20 is poor, the wafer W may shift in the Y-axis direction. Therefore, the displacement in the Y-axis direction is measured.

Main controller 28 compares the measured values of LS1 and LH1 and, if they are the same value, determines the Y value of wafer W.
It is determined that there is no displacement in the axial direction. On the other hand, when the values of LS1 and LH1 are different, main controller 28
It is determined that the wafer W is shifted in the Y-axis direction. And
Main controller 28 determines the amount of displacement of wafer W in the Y-axis direction and the direction of displacement (+ Y direction or −Y direction) based on the measured values of LS1 and LH1 in the same manner as in the X-axis direction described above. Ask for.

The main controller 28 obtains the positioning accuracy when the XY stage 20 is moved in the X-axis direction from the positional deviation information in the X-axis direction and the Y-axis direction obtained as described above. Further, in the present embodiment, since the patterns are superposed, the accuracy of the pattern superposition control can be obtained.

Note that the above description is based on the assumption that X
Although the case where the Y stage 20 is moved in the −X direction is described, the positioning accuracy of the XY stage 20 is similarly obtained when the Y stage 20 is moved in other directions (the + X direction, the + Y direction, the −Y direction, etc.). Can be.

In this embodiment, in the moving step, XY
FIG. 9 shows an example of a transfer image formed on the wafer W in the second exposure step when the stage 20 is moved in the + X direction. The dotted line in FIG. 9 is a transferred image (latent image) transferred in the first exposure step, and the solid line is a transferred image (latent image) transferred in the second exposure step. XY stage 20
Is moved in the −X direction, a reference mark image is formed at each of the overlapping portions of the transfer images TP1W and TP2W and the overlapping portion of the transfer images TP5W and TP6W, and the transfer image T
P3W overlaps TP4W, and transfer images TP7W and T
A comparative mark image is formed on each of the overlapping portions of P8W. Then, based on the lengths of the reference mark image and the comparison mark image measured in the same manner as in the measurement step, the positioning accuracy of the XY stage 20 can be obtained in the same manner as in the calculation step.

As shown in FIG. 10, a reticle R _T ′ having a measurement pattern RP 1 ′ formed by rotating the measurement pattern RP 1 by 90 degrees clockwise in the XY plane is formed on the pattern surface. XY in the moving step
The positioning accuracy of the XY stage 20 when the stage 20 moves in the Y-axis direction can be obtained. Here, the measurement pattern RP1 'includes patterns TP1' to TP8 'obtained by rotating the patterns TP1 to TP8 by 90 degrees clockwise in the XY plane. in this case,
The patterns TP2 ', TP4', TP6 ', TP8'
Patterns TP1 ', TP3', TP5 ', TP, respectively
7 ', the center of the pattern TP1', the center of TP2 ', and the pattern TP3.
′ And the center of TP4 ′, the center of the pattern TP5 ′ and the center of TP6 ′, and the center of the pattern TP7 ′ and the center of TP8 ′ are separated by ΔRY in the Y-axis direction. In this case, in the moving step, if the magnification of the projection optical system PL is, for example, ４, the main controller 28 moves the XY stage 20 in the Y-axis direction by a distance of ΔRY / 4. For example, FIG. 11 shows an example of a transferred image formed on the wafer W in the second exposure step when the XY stage 20 is moved in the −Y direction in the moving step. A dotted line in FIG. 11 indicates a transferred image (latent image) transferred in the first exposure step, and a solid line indicates a transferred image (latent image) transferred in the second exposure step. FIG. 12 shows an example of a transferred image formed on the wafer W in the second exposure step when the XY stage 20 is moved in the + Y direction in the moving step. The dotted line in FIG. 12 is the transferred image (latent image) transferred in the first exposure step, and the solid line is the transferred image (latent image) transferred in the second exposure step. In any case, the overlap between the transfer image TP1'W of the pattern TP1 'and the transfer image TP2'W of the pattern TP2', and the overlap of the transfer image TP5'W of the pattern TP5 'and the transfer image TP6'W of the pattern TP6'. The reference mark image is provided in each part, and the pattern TP3 '
Transfer image TP3'W and transfer image TP4 of pattern TP4 '
'W overlapped portion and transfer image TP7 of pattern TP7'
A comparative mark image is formed at each overlapping portion of 'W and the transfer image TP8'W of the pattern TP8'. Then, based on the lengths of the reference mark image and the comparison mark image measured in the same manner as in the measurement step, X is calculated in the same manner as in the calculation step.
The positioning accuracy of the Y stage 20 can be obtained.
In this case, instead of using the reticle R _T ′,
The reticle _RT on which the measurement pattern RP1 is formed on the pattern surface may be rotated clockwise by 90 degrees in the XY plane.

As described above, the XY stage 20 is
The positioning accuracy when moving in the axial direction and the positioning accuracy when moving in the Y-axis direction can be obtained.

Next, reticle R _T (reticle stage R
A method for obtaining the positioning accuracy (a type of position control accuracy) in ST) will be briefly described. XY stage 2 mentioned above
The only difference from the case of obtaining the positioning accuracy of 0 is that the reticle stage RST is moved instead of moving the XY stage 20 in the moving process.

That is, in the moving process, the main controller 28 monitors the position information of the reticle stage RST from the reticle interferometer 21 while keeping the XY stage 20 stationary, based on the positional relationship of each pattern. The reticle stage RST is moved via the drive system 29. Here, for example, when using a reticle R _T ′ in which the measurement pattern RP1 ′ shown in FIG. 10 is arranged on the pattern surface, the reticle stage RST is moved by ΔR in the Y-axis direction.
The drive system 29 is controlled so as to move by Y. Thus, in the second exposure step, similarly to the case where the XY stage 20 is moved, the reference mark images are respectively formed on the overlapping portions of the transfer images TP1W and TP2W and the overlapping portions of the transfer images TP5W and TP6W. Images TP3W and TP
Comparative mark images are formed on the 4W overlapping portion and on the overlapping portions of the transferred images TP7W and TP8W. Then, main controller 28 obtains the positioning accuracy of reticle stage RST in a manner similar to the calculation step, based on the lengths of the reference mark image and the comparison mark image measured in the same manner as the measurement step. However, in this case, it is necessary to determine the positioning accuracy of the reticle stage RST by using the value obtained by multiplying the measured position shift amount by the reciprocal (four times) of the projection magnification as the true position shift amount.

Next, a method of obtaining the synchronization accuracy (a type of position control accuracy) between the XY stage 20 and the reticle stage RST during scanning exposure will be briefly described. The only difference from the above-described case of obtaining the positioning accuracy of the XY stage 20 is that in the first exposure step and the second exposure step, exposure is performed while moving the XY stage 20 and the reticle stage RST in synchronization. is there.

Main controller 28 includes a reticle stage RS
When the T and XY stages 20 are positioned at a predetermined scanning start position (acceleration start position), reticle stage RS
The relative scanning of the T and XY stages 20 in the Y-axis direction is started. When the two stages reach their respective target scanning speeds and reach a constant-speed synchronization state, the pattern area of the reticle _RT starts to be illuminated by the ultraviolet pulse light from the illumination system IOP, and scanning exposure is started. The relative scanning is performed by the main controller 28 controlling the drive systems 22 and 29 while monitoring the measurement values of the laser interferometer 26 and the reticle interferometer 21 described above.

At the time of the above-mentioned scanning exposure, main controller 28 controls moving speed Vr of reticle stage RST in the Y-axis direction.
And the moving speed Vw of the XY stage 20 in the Y-axis direction are equal to the projection magnification (1/4 or 1/5) of the projection optical system PL.
The synchronous control is performed so that the speed ratio is maintained according to.

When the first scanning exposure (first exposure process) on wafer W is completed, main controller 28 controls reticle stages RST and X in accordance with the positional relationship of the measurement pattern.
The Y stage 20 is positioned at the next scanning start position (acceleration start position) (moving step). The main controller 28
Performs the second scanning exposure (second exposure step) in the same manner as described above.

By the second exposure step, a reference mark image and a comparison mark image are formed on wafer W. Then, main controller 28 obtains positional deviation information based on the lengths of the reference mark image and the comparison mark image measured in the same manner as in the measurement step, in the same manner as in the calculation step.

Further, main controller 28 obtains synchronization accuracy between XY stage 20 and reticle stage RST from the positional deviation information and the positioning accuracy of XY stage 20 and reticle stage RST which have already been measured. Note that the synchronization accuracy can be obtained for each moving direction of the XY stage 20 and the reticle stage RST (+ Y direction and -Y direction).

XY stage 2 obtained in this way
The data of 0 and the position control accuracy of the reticle stage RST are input to the main controller 28 of the exposure apparatus 100 and stored in a storage device (not shown). The main controller 28
Based on the accuracy data, the control data of the drive system 22 and the drive system 29 are controlled so that the positioning control of the XY stage 20 and the reticle stage RST and the synchronization control of the XY stage 20 and the reticle stage RST are accurately performed. adjust.

In the exposure apparatus 100 of the present embodiment,
As described above, the drive system 22 and the drive system 29 are controlled using the adjusted control data to perform positioning of the XY stage 20 and the reticle stage RST.
Scanning exposure is performed while performing synchronous control of the Y stage 20 and the reticle stage RST. Here, if the position cannot be controlled within the predetermined accuracy range, main controller 28 displays a warning on a display (monitor), or provides assistance to an operator or the like through the Internet (e-mail or the like) or a mobile phone. The need may be notified. Further, in this case, information necessary for adjustment of each drive system and sensors may be notified together. As a result, not only the work time for measurement of various data and the like but also the preparation period can be shortened, and the stop period of the exposure apparatus can be shortened, that is, the operation rate can be improved.

When the above equation (5) is modified, the following equation (6) is obtained.

ΔSH2 = ΔX5 × 2 ÷ tan (θ / 2) (6)

Here, if 2 ÷ tan (θ / 2) is set to M, the above equation (6) becomes the following equation (7).

ΔSH2 = ΔX5 × M (7)

From the above equation (7), it can be said that ΔSH2 is a value obtained by multiplying ΔX5 by M. That is, it is possible to measure the position shift amount while enlarging it. For example, if the displacement amount is 50
In order to increase the angle (M = 50), the angle θ should be set to about 4.6 degrees, and to increase the displacement amount 100 times (M = 100), the angle θ should be set to about 2.3 degrees. . Therefore, it is possible to arbitrarily set the enlargement ratio M of the displacement amount by changing the angle θ.

As described above, in the present embodiment, when measuring the position control accuracy of each stage described above, the shape of the overlapping portion becomes a constant shape regardless of the overlapping position when the images are transferred in an overlapping manner. A first set of patterns including a pattern and a second pattern has the same mutual positional relationship as the positional relationship between the first pattern and the second pattern, and the shape of the overlapping portion when transferred in an overlapping manner is changed. A second set of patterns including a third pattern and a fourth pattern that change depending on the relative overlapping position are formed on the pattern surface PA so as not to overlap each other as measurement patterns. A reticle _RT is used. Therefore, a reference mark image formed at an overlapping portion of the first pattern and the second pattern,
The positional displacement information of the pattern can be obtained from the shape of the comparative mark image formed at the overlapping portion of the third pattern and the fourth pattern.

In the present embodiment, since the line width of each pattern is equal, each transfer image of each pattern is affected by the same degree of aberration of the projection optical system PL. Therefore, the influence of aberration on the reference mark image and the comparison mark image formed in the overlapping portion of each pattern can be considered to be substantially the same. Therefore, it is possible to eliminate the influence of aberration in the positional displacement information of the pattern calculated from the lengths of the corresponding portions of the reference mark image and the comparison mark image, and as a result, the reticle stage R
The position control accuracy of the ST or XY stage 20 (or the control accuracy of the relative position of both stages) can be measured.

Further, since both the reference mark image and the comparison mark image have the same pair of diagonal angles θ, the defects such as the resist occurring at the sharp tip portions are the same in both images. In addition, the effect of the process on the development process or the etching process can be considered to be substantially the same. Therefore, as a result, it is possible to accurately measure the position control accuracy of the reticle stage RST or the XY stage 20 (or the control accuracy of the relative position of both stages).

Further, the length of the comparative mark image includes the actual positional deviation amount enlarged at a magnification corresponding to the diagonal angle θ. Therefore, by arranging each pattern so as to obtain an angle θ corresponding to a predetermined magnification, the conventional method cannot measure the distance due to the measurement limit (resolution) of a measuring device that measures the distance between transfer images. Even if the amount of misalignment is large, the amount of misalignment is measured by using the same measuring device as the related art (for example, an alignment detection system (LSA system, FIA system) of an exposure apparatus) without using a special device. It becomes possible. That is, apparently, the resolution of the measuring device can be increased. Therefore, as a result, reticle stage RST or XY stage 2
It is possible to measure the position control accuracy of 0 (or the control accuracy of the relative position of both stages).

Further, since the displacement can be enlarged and measured in this manner, a special device is not required, and for example, an alignment detection system (LSA system, FIA system) provided in the exposure apparatus can be used. ), Etc., it is possible to measure even a slight displacement amount which cannot be measured conventionally. Also, reticle stage RST
When the position of the XY stage 20 is controlled, a length measuring device (for example, a reticle interferometer 21
Or reticle stage RST or XY stage 2 with higher accuracy than before.
The position accuracy of 0 can be measured.

In the above embodiment, the XY stage 2
In measuring the position control accuracy of 0, the first exposure process and the second
In the exposure step, the illumination area is set to match the area where the measurement pattern RP1 of the reticle _RT is arranged. However, the present invention is not limited to this, and the patterns TP1, TP3, and TP3 are set prior to the first exposure step. The illumination area is set so that the illumination light is emitted only to the area including TP5 and TP7,
Prior to the second exposure step, patterns TP2, TP4, TP
6, an illumination area may be set so that illumination light is emitted only to an area including TP8.

Further, in the above embodiment, the case where the line width of each pattern is equal has been described. However, the present invention is not limited to this, and instead of the measurement pattern RP1, for example, shown in FIG. Measurement pattern R
A reticle on which P2 is arranged can be used. Here, in the measurement pattern RP1, the pattern TP4
TP in which line width is reduced to 代 わ り instead of TP8 and TP8
4A and TP8A are arranged.

When the measurement pattern RP2 is transferred onto the wafer W in the same manner as the measurement pattern RP1 described above, in the second exposure step, as shown in FIG. Latent image of wafer W
Formed on top. The dotted line in FIG. 14 is a transferred image (latent image) transferred in the first exposure step, and the solid line is a transferred image (latent image) transferred in the second exposure step. After the development of the wafer W, as shown in FIG. 15 as an example, the transfer image TP1W of the pattern TP1 and the transfer image TP of the pattern TP2
2W overlapping portion and transfer image TP5W of pattern TP5
The reference mark images SM1A and SM2A are formed at the overlapping portions of the transfer image TP6W of the pattern TP6 and the transfer image TP3W of the pattern TP3 and the transfer image TP4AW of the pattern TP4A, respectively, and the transfer image T of the pattern TP7.
Comparative mark images HM1A and HM2A are formed at the overlapping portions of P7W and the transfer image TP8AW of the pattern TP8A, respectively. Then, based on the lengths of the reference mark image and the comparison mark image measured in the same manner as in the measurement step, the position control accuracy of the reticle _RT and the wafer W can be obtained in the same manner as in the calculation step. However, in this case, the line widths of the patterns TP4A and TP8A are
Since the line width of P7 is の, the length of the longer diagonal line in the reference mark image is set as a reference, and this value is compared with the length of the longer diagonal line in the comparison mark image. The accuracy of the position control will be determined. That is,
The accuracy of the position control in the Y-axis direction is determined in the same manner as described above from the difference between half of the longer diagonal length LS1A of the reference mark image SM1A and the longer diagonal length LH1A of the comparison mark image HM1A. The accuracy of the position control in the X-axis direction is determined in the same manner as described above from the difference between 1/2 of the longer diagonal length LS2A of the reference mark image SM2A and the longer diagonal length LH2A of the comparison mark image HM2A. Ask for. Note that the line widths of the patterns TP4A and TP8A are not limited to の of the line widths of the patterns TP3 and TP7, and the line widths of the patterns TP4A and TP8A may be larger than the line widths of the patterns TP3 and TP7.

In this case, the patterns TP1 to TP3 and T
Each of the transfer images P5 to TP7 is affected by the aberration of the same projection optical system PL, but the transfer images of the patterns TP4A and TP8A have different patterns TP due to the difference in line width.
The transfer images 1 to TP3 and TP5 to TP7 are affected by different aberrations. Therefore, the influence of the aberration on the reference mark image is different from the influence of the aberration on the comparative mark image. That is, even if the positioning accuracy is the same, the transfer images of the patterns TP4A and TP8A are formed at different positions when the line widths of all the patterns are equal. This means that the length of the comparison mark image formed is different from the case where the line widths of all the patterns are equal. Therefore, it is possible to obtain a change in the transfer position due to the influence of the aberration based on the shift information of the overlapping position calculated from the length of the reference mark image and the length of the comparison mark image. This makes it possible to perform positioning control in consideration of the line width of the pattern.

In place of the measurement pattern RP1,
A reticle having a measurement pattern RP3 as shown in FIG. 16 can be used. In this reticle, the pattern T in the measurement pattern RP1 described above is used.
Pattern TP3 with changed line width instead of P3 and TP4
Patterns TP7B and TP8B with changed line widths are arranged instead of B, TP4B, and patterns TP7 and TP8. That is, the patterns TP1, TP2, TP5,
TP6 has the first line width, respectively, and the pattern TP3
B, TP4B, TP7B, and TP8B each have a second line width.

Also in this case, the measurement pattern RP described above is used.
In the same manner as in the case of 1, the shift information of the overlapping position can be obtained. In addition, here, the reference mark image is formed by superimposing transfer of the pattern having the first line width, and the comparative mark image is an image formed by superimposing transfer of the pattern having the second line width. The image is affected by the aberration corresponding to the first line width, and the comparative mark image is affected by the aberration corresponding to the second line width. That is,
Since the reference mark image and the comparison mark image are affected by different aberrations, even if the positioning accuracy of the superposition is the same, the position of the first mark and the second mark are different from each other. Pattern TP3B, TP4B and pattern T
Transfer images of P7B and TP8B are formed. This means that the length of the comparison mark image to be formed is different from the case where the first line width is equal to the second line width. Therefore, it is possible to obtain a change in the transfer position due to the influence of the aberration based on the shift information of the overlapping position calculated from the length of the reference mark image and the length of the comparison mark image. This allows
Positioning control can be performed in consideration of the line width of the pattern.

In the above-described embodiment, the second set of patterns for forming the comparative mark image includes a linear first portion extending in the first direction and a linear second portion extending in the second direction. And, as a whole, mountain-shaped patterns TP3 and TP7,
It has a linear first portion extending in the first direction and a linear second portion extending in the second direction, and has patterns TP3, T
It is composed of P7 and a chevron pattern TP4, TP8 in the opposite direction, but is not limited to this. For example, one pattern constituting the second set of patterns is:
Instead of a mountain shape, a line pattern may be used. For example,
As shown in FIG. 17, in the measurement pattern RP1, a line pattern TP3C extending in the X-axis direction as the fifth direction instead of the pattern TP3, and a line pattern TP7C extending in the Y-axis direction instead of the pattern TP7 are arranged. Further, instead of the pattern TP4, a first portion extending in a sixth direction forming an angle θ with respect to the X-axis direction and a second portion extending in a seventh direction different from the sixth direction forming an angle θ with respect to the X-axis direction are formed. TP4C that has a chevron pattern as a whole
A measurement pattern RP4 in which a pattern TP8C having a shape obtained by rotating the pattern TP4C by 90 degrees counterclockwise in the drawing in place of the pattern TP8 may be used. In this case, the direction of the pattern TP1 (third direction) is the same as the first direction, and the direction of the pattern TP2 (fourth direction) is the same as the second direction.

When the measurement pattern RP4 is transferred onto the wafer W in the same manner as in the case of the measurement pattern RP1 described above, in the second exposure step, as shown in FIG. Latent image of wafer W
Formed on top. The dotted line in FIG. 18 is a transfer image (latent image) transferred in the first exposure step, and the solid line is a transfer image (latent image) transferred in the second exposure step. After the development, as shown in FIG. 19 as an example, the transferred image TP of the pattern TP1
The reference mark image SM is provided at the overlapping portion of the transfer image TP2W of the pattern TP2 and the transfer image TP5W of the pattern TP5 and the transfer image TP6W of the pattern TP6.
1C and SM2C are formed, and comparative mark images HM1C and HM2C are respectively formed in an overlapping portion of the transferred image TP3CW of the pattern TP3C and the transferred image TP4CW of the pattern TP4C and an overlapping portion of the transferred image TP7CW of the pattern TP7C and the transferred image TP8CW of the pattern TP8C. It is formed.

The shapes of the reference mark images SM1C and SM2C are squares (diamonds) each having a pair of diagonal angles of an angle θ.
The shape of each of the comparative mark images HM1C and HM2C is an isosceles triangle having a pair of base angles of an angle θ. Even in this case, the shape of the comparison mark image is a shape that changes depending on the overlapping position. That is, the comparison mark image HM1
The shapes of C and HM2C are isosceles triangles each having a base of the X-axis direction and the Y-axis direction and a pair of base angles of an angle θ.
The comparative mark image HM1C has a base length LH1C extending in the X-axis direction, and the comparative mark image HM2C has a base length LH2C extending in the Y-axis direction as the comparative mark image length. The position control accuracy of the reticle stage (reticle) or wafer stage (wafer) can be obtained based on the measured lengths of the reference mark image and the comparison mark image in the same manner as in the calculation step.

In particular, when a resist image is obtained by developing a wafer, or when an etched image is obtained by etching a wafer on which a resist image is formed, a pair of diagonals in a reference mark image and a comparative mark are compared. 2 in the image
Since the two internal angles are the same angle θ, in both images, the defects such as resist occurring at the sharp tip portions are almost the same, and the influence of the process in the developing process or the etching process is almost the same. Can be considered to be. Therefore, it is possible to accurately measure the position control accuracy of the reticle stage (reticle) or wafer stage (wafer).

In this case, the patterns TP3 and TP
7 instead of pattern TP3C and pattern TP7C
A pattern having a chevron in a direction opposite to the above can be used. Further, the positions of the patterns TP3C and TP4C and the positions of the patterns TP7C and TP8C may be interchanged.

Even in this case, the length of the comparison mark image includes the actual positional deviation amount enlarged by a magnification corresponding to the angle θ between the two inner angles. Therefore, by arranging each pattern so as to obtain an angle θ corresponding to a predetermined magnification, in the conventional method, the measurement cannot be performed due to the measurement limit (resolution) of the measurement device that measures the distance between transfer images. Even with a large amount of misalignment, a special measuring device is not required and the same measuring device as the conventional one (for example, an alignment detection system (LSA system, FIA
) Can be used to measure the displacement amount. That is, apparently, the resolution of the measuring device can be increased. Therefore, as a result, it is possible to measure the position control accuracy of the reticle or wafer with higher accuracy. Further, as described above, it is also possible to determine the influence of the aberration of the projection optical system on the transfer position by making the line width of some patterns different from that of other patterns.

In the above description, the case where the reference mark image is formed by overlapping transfer of line patterns having the same line width is described, but the present invention is not limited to this.
For example, when line patterns having different line widths are superimposed and transferred, the overlapping portion becomes a parallelogram. However, even if this is the case, the overlapping portion has a constant shape regardless of the overlapping position, and is used as a reference mark image. be able to. That is, when the images are superimposed and transferred, the image formed on the overlapping portion only needs to have a constant shape regardless of the overlapping position, and the shape is not limited.

In the above embodiment, a measurement pattern composed of eight types of patterns is used, but the present invention is not limited to this. For example, when measuring the displacement information in the X-axis direction when the XY stage 20 is moved in the X-axis direction, it may be constituted by four types of patterns TP5 to TP8.

Further, instead of the pattern (TP1, TP2, TP5, TP6) for forming the reference mark image, a line and space pattern in which a plurality of line patterns in the same direction are periodically arranged may be used. good.
In this case, since a reference mark image is obtained for each line pattern, the reticle stage (reticle) or wafer can be more accurately used by using the average value (simple average or weighted average) of the lengths of the reference mark images. The position control accuracy of the stage (wafer) can be measured.

Similarly, in the pattern (TP3, TP4, TP7, TP8, etc.) for forming the comparative mark image, a plurality of patterns having the same shape may be arranged. In this case, a plurality of comparison mark images are obtained, and the average value (simple average or weighted average) of the lengths of the respective comparison mark images is obtained.
Is used, it becomes possible to measure the position control accuracy of the reticle stage (reticle) or wafer stage (wafer) with higher accuracy.

Further, in the above embodiment, a measurement pattern having one kind of positional relationship is used, but a measurement pattern having a plurality of positional relationships may be used. For example, the position control accuracy is measured for each of a plurality of movement amounts of the substrate, and the relationship between the movement amount and the position control accuracy can be obtained.

In the above embodiment, the measurement pattern is arranged only at one place in the pattern area of the reticle. However, the measurement pattern is arranged at a plurality of places in the pattern area. An average value (such as a simple average value or a weighted average value) of positional deviation information or position control accuracy obtained for each may be obtained. As a result, it is possible to obtain the position control accuracy of the reticle stage (reticle) or wafer stage (wafer) with higher accuracy (or the control accuracy of the relative position of both stages).

Further, in the above embodiment, as described above, since a series of measurement operations are automatically performed by connecting the coater / developer in-line, a great merit such as reduction in human load is expected.

In the above embodiment, the case where the diagonal lines of the reference mark image and the comparison mark image are in the X-axis direction and the Y-axis direction has been described. This is for the purpose of obtaining a good result, and the present invention is not limited to this.

Further, in the above embodiment, the position control accuracy of the reticle or the wafer is measured based on the length of the diagonal line between the reference mark image and the comparison mark image. However, the present invention is not limited to this. In other words, if the length of the corresponding portion of both mark images is the same, the position control accuracy of the reticle or wafer can be measured. Therefore, position shift information is calculated based on the lengths of a plurality of corresponding portions, and the position control accuracy of the reticle stage (reticle) or wafer stage (wafer) is calculated from the average value (simple average value or weighted average value). You may ask.

In the above embodiment, the length of the resist image is measured. However, for example, the length of a latent image or an image obtained by etching a wafer on which a resist image is formed is measured. You may do it.

Further, in the above embodiment, the length of the transferred image is optically detected by the alignment detection system or the like. However, the present invention is not limited to this.
(Electrical Critical Dimension: a measuring method using electric resistance) or the like.

In the above-described embodiment, the measurement pattern is formed as a light-shielding portion having a predetermined shape in the light-transmitting portion. It may be formed. However, in this case, it is preferable to use a negative type photoresist as a photosensitive agent applied to the wafer.

Further, a drawing error of the measurement pattern formed on the reticle may be detected in advance, and the determination may be made in consideration of the detection result when calculating the above-described position control accuracy. As a result, it is possible to obtain the position control accuracy of the reticle stage (reticle) or wafer stage (wafer) with higher accuracy (or the control accuracy of the relative position of both stages).

Further, in the above embodiment, the case where the present invention is applied to the step-and-scan type scanning exposure apparatus has been described. However, it is needless to say that the applicable range of the present invention is not limited to this. That is, the present invention 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.

In particular, in the case of a step-and-repeat type projection exposure apparatus, in the first exposure step and the second exposure step, exposure is performed while the substrate stage and the mask stage are stationary, thereby performing the same operation as in the above embodiment. Thus, the position control accuracy of the mask stage (mask) or the substrate stage (substrate) can be obtained.

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

The light source of the exposure apparatus to which the present invention is applied is not limited to a KrF excimer laser or an 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, a fiber doped with, for example, erbium (or both erbium and ytterbium) is used as the exposure illumination light, for example, a single-wavelength laser beam in the infrared or visible range oscillated from a DFB semiconductor laser or a fiber laser. A harmonic that has been amplified by an amplifier and wavelength-converted to ultraviolet light using a nonlinear optical crystal may be used.

Further, the present invention relates to an exposure apparatus for transferring a device pattern onto a glass plate, which is used not only for an exposure apparatus used for manufacturing a semiconductor element but also for a display including a liquid crystal display element and a plasma display. Exposure equipment used in the manufacture of thin-film magnetic heads for exposing device patterns onto ceramic wafers, imaging devices (such as CCDs), micromachines, and DNA chips, as well as exposure used in the manufacture of masks or reticles. It can also be applied to devices and the like.

In the above embodiment, the case where the length of the reference mark image and the comparison mark image are measured using the LSA system of the alignment detection system AS when measuring the position control accuracy of the mask and the substrate has been described. However, the present invention is not limited to this. For example, the image of each mark image may be captured using the FIA system of the alignment detection system AS, and the length measurement of each mark image may be measured by image processing based on the image signal. Even in this manner, the position control accuracy of the mask stage (mask) or the substrate stage (substrate) can be obtained with the same or higher accuracy as in the above embodiment.

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

FIG. 20 shows devices (semiconductor chips such as ICs and LSIs, liquid crystal panels, CCDs, thin-film magnetic heads,
A flow chart of a manufacturing example of a DNA chip, a micromachine, etc.) is shown. As shown in FIG. 20, first, in step 301 (design step), a function / performance design of a device (for example, circuit design of a semiconductor device) is performed, and a pattern design for realizing the function is performed. Subsequently, in step 302 (mask manufacturing step), a mask on which the designed circuit pattern is formed is manufactured. On the other hand, in step 303 (wafer manufacturing step), a wafer is manufactured using a material such as silicon.

Next, in step 304 (wafer processing step), actual circuits and the like are formed on the wafer by lithography using the mask and the wafer prepared in steps 301 to 303, as will be described later. Next, step 305 (device assembly step)
In, 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 necessary.

Finally, step 306 (inspection step)
In step 305, 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. 21 shows a detailed flow example of step 304 in the case of a semiconductor device. In FIG. 21, step 311 (oxidation step)
In, 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
At 14 (ion implantation step), ions are implanted into the wafer. Steps 311 to 314 described above
Each of them constitutes a pre-processing step in each stage of wafer processing, and is selected and executed according to a necessary process in each stage.

In each stage of the wafer process, when the above-mentioned pre-processing step is completed, the post-processing step is executed as follows. In this post-processing step, first, in step 3
In 15 (resist forming step), a photosensitive agent is applied to the wafer. Subsequently, in step 316 (exposure step), the circuit pattern of the mask is transferred to the wafer by the exposure apparatus and the exposure method of the above embodiment. Next, in step 317 (development step), the exposed wafer is developed, and in step 318 (etching step), the exposed members other than the portion where the resist remains are removed by etching. Then, in step 319 (resist removing step), unnecessary resist after etching is removed.

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

According to the device manufacturing method of this embodiment as described above, the exposure apparatus and the exposure method of the above embodiment are used in the exposure step, and the accuracy data measured by the above-described position control accuracy measurement method is used. Stage (mask) with high accuracy based on control data adjusted in consideration of
Alternatively, since the position of the substrate stage (substrate) is controlled, highly accurate exposure is performed, and a highly integrated device can be manufactured with high productivity.

[0174]

As described above in detail, according to the present invention, it is possible to provide a mask that can be suitably used for measuring the position control accuracy of a mask stage or a substrate stage.

Further, according to the position control accuracy measuring method according to the present invention, there is an effect that the position control accuracy of the mask stage (mask) or the substrate stage (substrate) can be accurately measured.

According to the exposure method of the present invention,
There is an effect that highly accurate exposure can be realized.

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

[Brief description of the drawings]

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

FIG. 2 is a diagram showing an example of a reticle used for measuring position control accuracy.

FIG. 3 is a diagram illustrating an example of a measurement pattern used for measuring position control accuracy (X-axis direction) of a mask and a substrate.

4 is a view showing an example of a transferred image (latent image) formed on a resist layer when performing double exposure using a reticle on which a measurement pattern shown in FIG. 3 is formed (wafer) In the -X direction).

FIG. 5 is a view showing the resist image of FIG. 4;

FIGS. 6A to 6C are diagrams for explaining the relationship between the shape of the reference mark image and the overlapping position.

FIGS. 7A to 7C are diagrams for explaining the relationship between the shape of the comparative mark image and the overlapping position.

FIGS. 8A and 8B are diagrams for explaining the relationship between the shape of the comparative mark image and the direction of displacement of the superposition position.

9 is a view showing an example of a transferred image (latent image) formed on a resist layer when performing double exposure using a reticle on which the measurement pattern shown in FIG. 3 is formed (wafer) In the + X direction).

FIG. 10 shows the position control accuracy of the mask and the substrate (Y-axis direction).
FIG. 6 is a diagram showing an example of a measurement pattern used for measurement of the measurement.

11 is a diagram showing an example of a transferred image (latent image) formed on a resist layer when double exposure is performed using the reticle on which the measurement pattern shown in FIG. 10 is formed (wafer) In the -Y direction).

12 is a diagram illustrating an example of a transferred image (latent image) formed on a resist layer when performing double exposure using a reticle on which the measurement pattern illustrated in FIG. 10 is formed (wafer) In the + Y direction).

FIG. 13 is a diagram illustrating an example of a measurement pattern different from that of FIG. 3;

14 is a view showing an example of a transferred image (latent image) formed on a resist layer when performing double exposure using a reticle on which the measurement pattern shown in FIG. 13 is formed (wafer) In the -X direction).

FIG. 15 is a view showing the resist image of FIG. 14;

FIG. 16 is a diagram showing an example of a measurement pattern different from FIGS. 3 and 13;

FIG. 17 is a diagram showing an example of a measurement pattern different from FIGS. 3, 13 and 16;

18 is a view showing an example of a transferred image (latent image) formed on a resist layer when performing double exposure using a reticle on which the measurement pattern shown in FIG. 17 is formed (wafer) In the -X direction).

FIG. 19 is a view showing the resist image of FIG. 18;

FIG. 20 is a flowchart illustrating an embodiment of a device manufacturing method according to the present invention.

FIG. 21 is a flowchart of a process in step 304 of FIG. 20;

[Explanation of symbols]

20 XY stage, 21 reticle interferometer, 26 laser interferometer, 28 main controller, 42 glass substrate (mask substrate), RP1 measurement pattern, SM1 reference mark image (for X-axis direction measurement) , SM2... Reference mark image (Y
HM1 ... comparison mark image (for X-axis direction measurement), HM2 ... comparison mark image (for Y-axis direction measurement), TP
1: first pattern, TP2: second pattern, TP3: third pattern (first line width), TP3B: third pattern (second line width), TP4: fourth pattern (first line width) , TP4A... Fourth pattern (second line width), PA.
Pattern area (pattern plane), PL: Projection optical system, R _T
… Reticle (mask), R… reticle (mask), RS
T: reticle stage, W: wafer (substrate).

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03F 7/22 G03F 7/22 H 9/00 9/00 H H01L 21/027 H01L 21/30 502P F-term (Reference) 2F065 AA21 CC20 JJ02 PP03 PP12 TT02 2H095 BA01 BA02 BA05 BB02 BB31

Claims (13)

[Claims] A first set of patterns including a first pattern and a second pattern in which the shape of an overlapping portion becomes a constant shape regardless of an overlapping position when transferred in an overlapping manner;
The third pattern and the fourth pattern have the same mutual positional relationship as the positional relationship between the pattern and the second pattern, and the shape of the overlapping portion changes depending on the relative overlapping position when transferred in an overlapping manner. A mask comprising a mask substrate formed on a pattern surface of the second set of patterns so that the patterns do not overlap with each other. 2. The first pattern is a pattern including at least one line pattern extending in a first direction, and the second pattern has an angle θ1 with respect to the first direction.
(0 <θ1 <180 °), the pattern including at least one line pattern extending in the second direction, wherein the third pattern includes a linear first portion extending in the first direction and the second direction. The second pattern is a chevron-shaped pattern as a whole, and the fourth pattern is a linear first portion extending in the first direction and a linear first portion extending in the second direction. 2. The mask according to claim 1, wherein the mask has two portions, and is a chevron-shaped pattern as a whole opposite to the third pattern. 3. 3. The first pattern includes at least one line pattern extending in a third direction, and the second pattern has an angle θ2 with respect to the third direction.
(0 <θ2 <180 °), the pattern including at least one line pattern extending in a fourth direction, wherein the third pattern has an angle θ2 / 2 with respect to the third direction and the fourth direction, respectively. A pattern including at least one line pattern extending in the fifth direction, wherein the fourth pattern forms an angle θ2 with the fifth direction.
A linear first portion extending in the second direction and a linear second portion extending in a seventh direction different from the sixth direction forming an angle θ2 with the fifth direction, and having a chevron pattern as a whole. The mask according to claim 1, wherein: 4. The mask according to claim 1, wherein the first to fourth patterns have the same line width. 5. The line width of the first to third patterns is equal, and the line width of the fourth pattern is different from the line width of the first to third patterns. The mask according to claim 1. 6. The method according to claim 1, wherein the first and second patterns have a first line width, and the third and fourth patterns have a second line width. The mask according to claim 1. 7. A position control accuracy measuring method for measuring the accuracy of position control using the mask according to claim 1, wherein the first and third patterns on the mask are arranged on a substrate. A first exposing step of transferring onto the substrate; a moving step of moving one of the mask and the substrate in a predetermined direction by a distance corresponding to a positional relationship between the first pattern and the second pattern; forming on the substrate The transferred images of the first pattern and the third pattern are combined with the second pattern and the fourth pattern on the mask.
A second exposure step of transferring the patterns in an overlapping manner; a reference mark image formed on an overlapping portion of a transfer image of the first pattern and the second pattern on the substrate;
A measuring step of measuring the length of each of the comparison mark images formed at the overlapping portion of the transfer image of the pattern and the fourth pattern; and position control based on the measured lengths of the reference mark image and the comparison mark image. A calculating step of calculating the accuracy of the;
Position control accuracy measurement method including: 8. The position control accuracy measurement according to claim 7, wherein in the calculation step, at least one of a positioning accuracy of one of the mask and the substrate and a pattern overlay accuracy is calculated. Method. 9. The position control accuracy measuring method according to claim 7, wherein in the first exposure step and the second exposure step, the exposure is performed with the mask and the substrate kept stationary. 10. The position control accuracy measurement method according to claim 7, wherein in the first exposure step and the second exposure step, the exposure is performed while the mask and the substrate are moved in synchronization. 11. The calculation step according to claim 10, wherein the synchronization accuracy between the mask and the substrate is calculated.
The position control accuracy measurement method described in 1. 12. An exposure method for transferring a pattern of a mask onto a substrate, wherein the step of measuring position control accuracy by the position control accuracy measurement method according to claim 7. Performing a position control of at least one of the mask and the substrate in consideration of the measured accuracy of the position control, and transferring a pattern of the mask onto the substrate. 13. A device manufacturing method including a lithography step, wherein the lithography step uses the exposure method according to claim 12.