JPH09246168A - Method and apparatus for scanning exposure and manufacture of device by use of this apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the number of generation of abnormal exposure shots to the minimum by the shift of a reticle during scanning exposure. SOLUTION: This apparatus causes a first mobile stage 4 which moves with a first substance 1 put on and a second mobile stage 5 which moves with a second substance 3 put on to perform scanning in synchronization with a projection optical system 2, and projects a pattern being on the first substance 1 onto the second substance 2 through the medium of the projection optical system. In this case, the position of the first substance 1 approximately fixed onto the first mobile stage 4 is measured during scanning exposure always, or when the first mobile stage 4 is at the starting position or at the finishing position of the scanning exposure, and the occurrence of a shift between the first mobile stage 4 and the first substance 1, and on the basis of the quantity of the detected shift the position of the first substance 1 is corrected during the scanning exposure alwalys, or before the start of the scanning exposure or after the finish of the scanning exposure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus used in a semiconductor manufacturing process, and more particularly to a projection exposure apparatus for projecting and transferring a reticle pattern onto a wafer. The present invention relates to a scanning exposure apparatus and method for scanning a reticle and a wafer in synchronization with a projection optical system.

[0002]

2. Description of the Related Art Recent advances in semiconductor device manufacturing technology have been remarkable, and the accompanying microfabrication technology has also advanced remarkably. In particular, the optical processing technology is mainly a reduction projection exposure apparatus having a resolution of sub-micron, commonly called stepper, and the numerical aperture (NA) of the optical system is expanded to further improve the resolution.
The exposure wavelength is being shortened.

Further, a conventional scanning exposure apparatus of the same size using a catoptric projection optical system is remodeled, a refracting element is incorporated in the projection optical system, and a reflecting element and a refracting element are combined, or only a refracting element is used. A scanning exposure apparatus that uses the configured reduction projection optical system to synchronously scan both the original stage (reticle stage) and the exposure substrate stage (wafer stage) at a speed ratio according to the reduction magnification is also drawing attention.

FIG. 19 shows an example of this scanning exposure apparatus.
A reticle 1 on which an original image is drawn is supported by a reticle stage 4 movable in the XYθ directions, and a wafer 3 which is a photosensitive substrate is supported by a wafer stage 5 movable in the XYθ directions. The reticle 1 and the wafer 3 are placed at optically conjugate positions via the projection optical system 2, and slit exposure light 6 extending in the X direction from the illumination system, not shown, illuminates the reticle 1, An image is formed on the wafer 3 in a size proportional to the projection magnification of the projection optical system 2. The scanning exposure scans the reticle 1 and the wafer 3 by moving both the reticle stage 4 and the wafer stage 5 with respect to the projection optical system 2 in the Y direction at a speed ratio according to the optical magnification with respect to the slit-shaped exposure light 6. Then, the entire surface of the pattern area 21 on the reticle 3 is transferred to the transfer area 22 on the wafer 3.

In order to perform scanning exposure, it is necessary to always perform scanning while accurately aligning the reticle 1 and the wafer 3. Therefore, the reticle stage 4 and the reticle 1 must be aligned, and the reticle 1 and the wafer 3 must be aligned.

Therefore, the following methods have hitherto been taken.
That is, as shown in FIG. 19, a plurality of reticle alignment marks 41 and 45 are arranged on the reticle 1, and alignment marks (reticle reference marks) 42 and 46 are also arranged on the reticle stage 4 at positions corresponding thereto.
First, the reticle alignment marks 41 and 45 of the reticle 1 and the reticle reference marks 42 and 46 of the reticle stage 4 are conveyed by an unillustrated conveying device onto an XYθ moving mechanism (not shown) on the reticle stage 4 and fixed by vacuum suction or the like. Are simultaneously observed with the reticle alignment observation microscopes 9 and 10 to determine the amount of deviation between the two marks. The reticle 1 is driven by an XYθ moving mechanism (not shown) of the reticle stage 4 so that the calculated deviation amount becomes zero. This completes the alignment between reticle 1 and reticle stage 4.

Next, the reticle stage 4 is driven so that the wafer alignment marks 43 and 47 on the reticle 1 are within the field of view of the wafer alignment observation microscopes 7 and 8. Wafer alignment marks 48 and 44 are arranged on the wafer 3 at positions corresponding to the wafer alignment marks 43 and 47 on the reticle 1 for each shot, and the wafer stage 5 is driven to perform wafer alignment on the wafer 3. The marks 48 and 44 are placed within the field of view of the wafer alignment observation microscopes 7 and 8. Then, the deviation amount between the two marks is measured. Wafer stage 5
The transfer area 22 of the wafer 3 is aligned with the pattern area 21 of the reticle 1 by driving the reticle 1 to measure the deviation amount between two marks in a plurality of shots and statistically processing the deviation amount of each shot. Correction is made to do. This completes the alignment between the reticle 1 and the wafer 3.

[0008]

However, in the above conventional example, the reticle 1 during exposure measures the position of the wafer stage 5 on the wafer 3 based on the measurement value of the interferometer 31 which measures the position of the reticle stage 4. Measuring interferometer 3
Since it is driven based on the measurement value of 5, there are the following drawbacks.

For example, assuming that the projection magnification of the lens is 1/4, the scanning speed of the reticle stage 4 is the wafer stage 5.
The scanning speed is 4 times the scanning speed, and if the throughput is emphasized, the acceleration and deceleration of the reticle stage 4 must be increased. For example, if the scanning speed of the wafer stage is 150
mm / s, the scanning speed of the reticle stage is 600
The speed is mm / s. In order to improve the throughput, the stationary reticle stage is 600 mm /
It is necessary to shorten the acceleration time required to accelerate to the speed of s as much as possible. Further, the reticle 1 is the wafer 3
This is about 8 times heavier than that of the above, and in such a case, there is a problem that the positional deviation between the reticle 1 and the reticle stage 4 is likely to occur during acceleration or deceleration during exposure. In order to prevent the positional deviation, it is sufficient to increase the suction area for fixing the reticle 1 by suction, but if this is done, there is a concern that the distortion of the reticle 1 will increase due to suction, so it cannot be increased unnecessarily.

If a positional deviation between the reticle 1 and the reticle stage 4 occurs during exposure, the reticle stage 4
Even if the relative position between the wafer stage 5 and the wafer stage 5 is controlled with high accuracy by the measurement values of the interferometers 31 and 35, the pattern region 21 on the reticle 1 is misaligned and transferred onto the wafer 3.

The detection of the misalignment of the reticle 1 is performed by moving the reticle stage 4 between the exposure of one shot and the exposure of the next shot by moving the reticle alignment marks 41 and 45 on the reticle 1 and the reticle stage. This can be achieved by observing the reticle reference marks 42 and 46 on the surface 4 simultaneously with the reticle alignment observation microscopes 9 and 10. However, it is not realistic because there is a problem that it takes time to move to the observation position and the throughput is significantly reduced.

An object of the present invention is to detect the occurrence of deviation of a reticle during scanning exposure and correct it to minimize the number of abnormal exposure shots caused by deviation, so that the device pattern on the reticle can be accurately printed on the wafer. It is to be transcribed.

Further, it is to prevent the generation of defective devices by notifying the operator of the location of the abnormal exposure shot due to the deviation.

[0014]

In order to achieve the above object, the scanning exposure apparatus according to the first embodiment of the present invention comprises a first movable stage on which a first object is mounted and which moves.
A second movable stage on which a second object is placed and moves, and the first and second movable stages are caused to scan in synchronization with a projection optical system, and the first object is passed through the projection optical system. In a scanning type exposure apparatus that projects the above pattern onto the second object, a position measuring unit that constantly measures the position of the first object that is substantially fixed on the first movable stage during scanning exposure, and the position measuring unit. Position deviation detection means for detecting the occurrence of a deviation between the first movable stage and the first object by an output signal from the means, and the position of the first object is constantly exposed during scanning exposure based on the deviation amount. It has a correction drive means for correcting. Preferably, the storage device further includes storage means for storing abnormal exposure shot information in which a positional deviation of the first object from the scan drive target position occurs during scanning exposure, and transmission means for transmitting the stored abnormal exposure shot information to an operator. .

The scanning exposure method according to the second aspect of the present invention includes a first movable stage on which a first object is placed and moves, and a second movable stage on which a second object is placed and moves. In a scanning type exposure method of scanning in synchronization with a projection optical system and projecting a pattern on the first object onto the second object via the projection optical system, the scanning exposure method is substantially fixed on the first movable stage. A position measuring step of constantly measuring the position of the first object during scanning exposure, and detecting that a deviation between the first movable stage and the first object has occurred from the position signal obtained in the position measuring step. And a correction drive step of constantly correcting the position of the first object during scanning exposure based on the amount of deviation that has occurred. Preferably, the method further includes a storage step of storing abnormal exposure shot information in which a positional deviation of the first object with respect to a scan drive target position occurs during scanning exposure, and a transmission step of transmitting the stored abnormal exposure shot information to an operator. .

In these configurations, during the scanning exposure of the position of the reticle suction-fixed on the first movable stage,
By constantly measuring, it is possible to detect and correct the deviation of the reticle with respect to the first movable stage during scanning exposure. This makes it possible to accurately transfer the device pattern on the reticle onto the wafer while minimizing the number of abnormal exposure shots due to the reticle displacement. Further, it is possible to prevent the occurrence of a defective device by detecting the occurrence of the reticle position deviation with respect to the scanning drive target position during the scanning exposure, storing the shot information in which the deviation occurred, and transmitting the information to the operator. .

The scanning exposure apparatus according to the third aspect of the present invention includes a first movable stage on which a first object is placed and moves, and a second movable stage on which a second object is placed and moves. Scanning exposure in which the first and second movable stages are scanned in synchronization with a projection optical system and the pattern on the first object is projected onto the second object via the projection optical system. In the apparatus, position measuring means capable of measuring the position of the first object substantially fixed on the first movable stage when the first movable stage is located at the scanning exposure start position or the scanning exposure end position, A position deviation detecting means for detecting an occurrence of a deviation between the first movable stage and the first object by an output signal from the position measuring means, and a position of the first object is scanned based on the deviation amount. Start exposure And having a correction drive means for correcting before or after the scanning exposure is completed. Preferably, further, storage means for storing abnormal exposure shot information in which a displacement of the first object with respect to the scan drive target value position during scanning exposure is stored, and transmission means for transmitting the stored abnormal exposure shot information to an operator. It is characterized by having.

The scanning exposure method according to the fourth aspect of the present invention includes a first movable stage on which a first object is placed and moves, and a second movable stage on which a second object is placed and moves. In a scanning type exposure method of scanning in synchronization with a projection optical system and projecting a pattern on the first object onto the second object via the projection optical system, the scanning exposure method is substantially fixed on the first movable stage. The position measurement step that enables the position of the first object to be measured when the first movable stage is located at the scanning exposure start position or the scanning exposure end position, and the position signal obtained in the position measurement step A position shift detecting step of detecting a shift between the first movable stage and the first object, and a position shift of the first object based on the generated shift amount before or after the scanning exposure starts or after the scanning exposure ends. And having a correction drive step of. Preferably, the method further includes a storage step of storing abnormal exposure shot information in which the positional deviation of the first object with respect to the scanning drive target position occurs during scanning exposure, and a transmission step of transmitting the stored abnormal exposure shot information to an operator. .

In these configurations, the throughput is measured by measuring the position of the reticle suction-fixed on the first movable stage when the first movable stage is positioned at the scanning exposure start position or the scanning exposure end position. It is possible to detect and correct the deviation of the reticle with respect to the reticle stage at the end of the scanning exposure without decreasing.
This makes it possible to accurately transfer the device pattern on the reticle onto the wafer while minimizing the number of abnormal exposure shots due to the reticle displacement. Further, it is possible to prevent the occurrence of a defective device by detecting the occurrence of the reticle position deviation with respect to the scanning drive target position during the scanning exposure, storing the shot information in which the deviation occurred, and transmitting the information to the operator. .

[0020]

【Example】

(First Embodiment) The present invention will be described in detail below with reference to the embodiments shown in the drawings. 1 and 2 show the first embodiment of the present invention.
2 shows a configuration of a scanning type exposure apparatus according to the embodiment of FIG. The flow is shown in FIG.

In FIGS. 1 and 2, the reticle 1 on which the original image is drawn has at least one end surface mirror-finished, and the beams 33, 34 from the laser interferometers 31, 32 are applied to the mirror surface portion. It is possible to measure the position of. The reticle 1 is placed on the reticle stage 4 which is driven and controlled in the XYθ directions by the length measuring means 104 and the drive control means 103, and the reticle stage 4 is
It is supported by a device body (not shown). The length measuring unit 104 measures the position in the scanning direction (Y direction in the drawing) by the laser interferometers 31 and 32, and measures the position in the non-scanning direction (X direction in the drawing) by the position measuring sensor 51 such as a capacitance sensor. To do. The wafer 3, which is a photosensitive substrate, is placed on the wafer stage 5 which is driven and controlled in the XYθ directions by the laser interferometers 35 and 37 and the drive control means 103, and the wafer stage 5 is supported by an apparatus body (not shown). There is. The reticle 1 and the wafer 3 are placed at optically conjugate positions via the projection optical system 2, and slit exposure light 6 extending in the X direction from the illumination system (not shown) is emitted by the reticle 1.
Is illuminated, and an image is formed on the wafer 3 in a size proportional to the projection magnification of the projection exposure system 2. The scanning exposure is performed by moving both the reticle stage 4 and the wafer stage 5 in the Y direction at a speed ratio according to the optical magnification with respect to the slit-shaped exposure light 6 to scan the reticle 1 and the wafer 3. The entire surface of the pattern area 21 on the wafer 3 is transferred to the transfer area 22 on the wafer 3.

The details of this embodiment will be described with reference to the flow chart of FIG.

First, prior to placing the reticle 1 on the reticle stage 4, the reticle stage 4 is driven to a reference position of the apparatus main body to perform alignment, that is, so-called origin position driving is executed. When the reticle 1 is mounted on the reticle stage 4 by a transport device (not shown) after the origin position drive is stopped and the reticle stage 4 is stationary, the reticle alignment marks 41 and 45 on the reticle 1 and the reticle alignment marks 41 and 45 are fixed. Both of the reticle reference marks 42 and 46 on the stage 4 are arranged to be within the field of view of the reticle alignment observation microscopes 9 and 10 (FIG. 4).
Step a).

In this state, the relative displacement of the reticle reference marks 42 and 46 on the reticle stage relative to the reticle alignment mark 41 or 45 on the reticle 1 is measured by the reticle alignment observation microscopes 9 and 1.
The signal obtained is observed photoelectrically at 0 and the obtained signal is detected by the mark detecting means 1.
01 and sends the relative positional relationship information to the arithmetic processing means 102.

Based on this information, the reticle 1 is moved in the XYθ directions, and alignment is performed so as to eliminate the relative displacement of each. By the above procedure, the reticle 1 is correctly positioned on the reticle stage 4 (step b in FIG. 4).

In this state, the beam positions are set so that the beams 33, 34 of the laser interferometers 31, 32 hit the side surface of the reticle 1. Further, the position on the side surface of the reticle 1 where the laser interferometer beams 33 and 34 strike is changed to a mirror surface 61.
And keep it. With this configuration, the position of the reticle 1 can be measured by the laser interferometers 31 and 32.

The laser interferometers 31 and 32 are reset when the origin position driving of the reticle stage 4 is completed and the alignment of the mounted reticle 1 is completed, and the origins of the laser interferometers 31 and 32 are set. (Figure 4
Step c).

Further, the position measurement sensor 51 such as a capacitance sensor for measuring the position of the reticle 1 in the X direction is used to measure the position of the reticle 1, and the measured value is stored as the reticle origin measured value X0. The capacitance sensor having a measurement resolution of about 5 nm is available on the market. If the reticle origin measurement is performed once for each wafer exposure, it can be performed at intervals of about 1 minute. Therefore, it is only necessary to guarantee the measurement stability in about 1 minute, so that a high degree of measurement stability can be obtained (step d in FIG. 4).

Next, according to the measurement values of the laser interferometers 31 and 32, the drive control means 103 controls the reticle stage 4.
The wafer alignment marks 43, 47 on the reticle 1.
Is driven in the Y direction by a predetermined amount so that the image data is within the field of view of the wafer alignment observation microscopes 7, 8. Further, the wafer stage 5 is driven in the X and Y directions by a predetermined amount so that the wafer alignment marks 44 and 48 on the wafer 3 are within the field of view of the wafer alignment observation microscopes 7 and 8. Wafer 3 for wafer alignment mark 43 or 47 on reticle 1
The relative position deviation of the upper wafer alignment marks 48, 44 is photoelectrically observed by the wafer alignment observation microscopes 7, 8 and the signals obtained are processed by the mark detection means 101 to obtain the relative positional relationship information of each. It is sent to the arithmetic processing means 102. This processing is executed for several shots, and the relative positional relationship information obtained from each shot is statistically processed,
The XY coordinates of the center of each shot are found so that the pattern area 21 on the reticle 1 and the transfer area 22 of each shot already exposed on the wafer 3 coincide with each other (step e in FIG. 4).

Next, according to the measurement values of the laser interferometers 31 and 32, the drive control means 103 controls the reticle stage 4.
To the exposure start position. Similarly, laser interferometer 3
According to the measured values of 5 and 37, the drive control unit 103 also drives the wafer stage 5 to the exposure start position which is deviated from the XY coordinates of each shot center by a predetermined amount (step f in FIG. 4).

Consider a case where a positional shift of the reticle 1 as shown in FIG. 3 occurs after the start of scanning exposure. Let Y1 and Y2 be the measurement values of the laser interferometers 32 and 31, Y1o be the drive target value in the Y direction, and Y2o be the measurement value of the sensor 51 that measures the position of the reticle 1 in the X direction. , The beam spacing of 32 is L,

[0032]

[Equation 1] Becomes Therefore, the inclination of the reticle 1 can be corrected by first driving the θ drive mechanism of the reticle stage 4 by Δθ. Next, the measurement is performed again, the shift amount is calculated, and the X drive shift of the reticle 1 can be corrected by driving the X drive mechanism of the reticle stage 4 by ΔX. Furthermore Y
The deviation in direction can be corrected by driving the Y driving mechanism of the reticle stage 4 by ΔY (step g in FIG. 4).

Although the deviation correction driving of the reticle 1 is always executed, the exposure accuracy is affected in the case of a large deviation. Therefore, the deviation occurrence detection means of the reticle 1 is XY
The measured value of θ is always observed, and it is determined that the abnormal deviation occurs only when the set tolerance is deviated (step h in FIG. 4).

To detect the deviation in the X direction, the absolute value of ΔX in the above equation (2) is always observed, and the preset tolerance value Xt is set.
It is recognized that abnormal deviation occurs when ΔX becomes larger than that. To detect the deviation in the Y direction, the absolute value of ΔY in the above equation (3) is constantly observed and compared with a preset tolerance value Yt, and when ΔY becomes larger, it is recognized that an abnormal deviation has occurred. In the deviation detection in the θ direction, the absolute value of Δθ in the above equation (1) is always observed and compared with a preset tolerance value θt, and when Δθ becomes larger, it is recognized that an abnormal deviation has occurred.

The alignment accuracy between the pattern area 21 on the reticle 1 and the transfer area 22 on the wafer 3 is generally required to be 1/3 or less of the designed line width. For example, if the design line width is 0.3 μm, the alignment accuracy is 100 n.
m or less. The details of the alignment accuracy include alignment accuracy, process factors, synchronization error between the reticle stage and wafer stage, and reticle misalignment error. Assuming that the alignment accuracy is 100 nm, the allowable value of the reticle misalignment error is assumed to be about 10 nm. This is the value on the wafer, so if converted to the value on the reticle, the projection magnification of the optical system is set to 1/4
Becomes Therefore, the tolerance values Xt, Y in the XYθ directions
The values of t and θt are 40 nm, 40 nm and 0.4, respectively.
It is desirable to set the value to about ppm.

It takes some time from the occurrence of the displacement of the reticle 1 to the completion of the XYθ correction drive. Therefore, if an abnormal deviation exceeding the tolerance value occurs during exposure of a certain shot, the shot becomes an abnormal exposure. The shot determined as abnormal deviation by the deviation occurrence detection means is recorded as a shot number in the storage means in the apparatus as an abnormal exposure shot, and after the exposure of all shots is completed, the operator takes appropriate measures. The abnormal exposure shot is displayed on the display device so that it can be performed (step i in FIG. 4). FIG. 16 shows a display example of the abnormal exposure shot on the display device.

Now, the mirror surface portion 61 of the end face of the reticle 1 will be described. The surface accuracy of the mirror surface portion 61 is preferably set to about λ / 20 (where λ is the wavelength of the interferometer) so as not to adversely affect the measurement accuracy even if the irradiation positions of the laser interferometer beams 33 and 34 change. . For example, if the wavelength λ is 633
nm, the surface accuracy λ / 20 of the mirror surface portion 61 is 31 nm.
Becomes

Further, the perpendicularity (horizontal and vertical directions) of the mirror surface portion 61 with respect to the optical axes of the laser interferometer beams 33 and 34 is also important. As is well known, the deviation of the squareness causes a cosine error and adversely affects the measurement accuracy. For example, when the optical path length of the laser interferometer beams 33 and 34 is 800 mm, a squareness of 2 '(minute) is required to suppress the cosine error to about 40 nm.

That is, the reticle alignment mark 41,
This means that the parallelism between the line connecting 45 and the mirror surface portion 61 should be within 2 '(minutes). In other words, it means that the parallelism between the pattern area 21 and the mirror surface portion 61 is within 2 ′ (minutes). If the perpendicularity between the line connecting the reticle reference marks 42 and 46 and the laser interferometer beams 33 and 34 is measured in advance, the cosine error due to this error can be calculated and can be corrected. Further, the alignment residual between the reticle alignment marks 41 and 45 and the reticle reference marks 42 and 46 can be obtained by measurement and can be corrected. Therefore, it is desirable that the parallelism between the line connecting the reticle alignment marks 41 and 45 and the mirror surface portion 61 is within 2 '(minute). It should be noted that the mirror surface portion 61 is sufficient not only on the end faces on which the laser interferometer beams 33 and 34 are irradiated, but only on the vicinity of the irradiation portion.

(Second Embodiment) The second embodiment of the present invention will be described in detail below. 5 and 6 show a second embodiment of the present invention.
2 shows a configuration of a scanning type exposure apparatus according to the embodiment of FIG. The flow is shown in FIG.

In the above-described first embodiment, the laser interferometer beam 3 by the scanning drive of the reticle stage 4 is used.
Since a cosine error due to a change in the optical path lengths of 3 and 34 becomes a problem, a highly accurate numerical value is required for the parallelism between the pattern area 21 and the mirror surface portion 61. Therefore, the manufacturing cost of the reticle becomes high, but in the second embodiment, a configuration is adopted in which the accuracy required for the parallelism is reduced.

In FIGS. 5 and 6, the reticle 1 on which the original image is drawn is placed on the reticle stage 4 which is drive-controlled in the XYθ directions by the length measuring means 104 and the drive control system 103, and the reticle stage 4 is It is supported by a device body (not shown). The length measuring unit 104 performs position measurement in the scanning direction (Y direction in the drawing) by the laser interferometers 81 and 82 fixed on the reticle stage 4 and the laser interferometer 31 fixed on the apparatus main body (not shown). The position measurement in the non-scanning direction (X direction in the figure) is similarly performed by the laser interferometer 83 fixed on the reticle stage 4. The wafer 3, which is a photosensitive substrate, has a laser interferometer 35,
The wafer stage 5 is mounted on the wafer stage 5 whose drive is controlled in the XYθ directions by the drive controller 37 and the drive control means 103, and the wafer stage 5 is supported by the apparatus main body (not shown). The reticle 1 and the wafer 3 are optically placed at a conjugate position via the projection optical system 2, and X in the figure from an illumination system (not shown).
The slit-shaped exposure light 6 extending in the direction illuminates the reticle 1, and an image is formed on the wafer 3 in a size proportional to the projection magnification of the projection exposure system 2. For scanning exposure, the reticle stage 4 and the wafer stage 5 are used for the slit-shaped exposure light 6.
Both are moved in the Y direction at a speed ratio corresponding to the optical magnification to scan the reticle 1 and the wafer 3, and the entire pattern area 21 on the reticle 3 is transferred to the transfer area 22 on the wafer 3.

Details of this embodiment will be described with reference to the flow chart of FIG. First, prior to placing the reticle 1 on the reticle stage 4, the reticle stage 4 is driven to the reference position of the apparatus main body to perform alignment, that is, so-called origin position driving is executed. When the reticle 1 is mounted on the reticle stage 4 by a transport device (not shown) after the origin position drive is stopped and the reticle stage 4 is stationary, the reticle alignment marks 41 and 45 on the reticle 1 and the reticle alignment marks 41 and 45 are fixed. Both the reticle reference marks 42 and 46 on the stage 4 are within the field of view of the reticle alignment observation microscopes 9 and 10 (step a in FIG. 8). In this state, the reticle alignment marks 41 on the reticle 1 are aligned. Or reticle stage 4 for 45
The relative positional deviations of the reticle reference marks 42 and 46 on the upper side of the reticle are observed by the observation microscopes 9 and 10 for reticle alignment.
The signal obtained is observed photoelectrically with the mark detection means 10
1 to process the relative positional relationship information of each processing unit 1
Send to 02. Based on this information, the reticle 1 is moved in the XYθ directions, and alignment is performed so as to eliminate the relative positional deviation of each. With the above procedure, the reticle 1 is correctly positioned on the reticle stage 4 (step b in FIG. 8).

In this state, laser interferometers 81, 82, 8
The beam position is set so that the laser interferometer beam No. 3 hits the side surface of the reticle 1. In addition, reticle 1
The position where the laser interferometer beam hits on the side of is set as a mirror surface. With this configuration, the position of the reticle 1 can be measured by the laser interferometers 81, 82, 83. In this state, the laser interferometers 81, 82, and 83 are reset to find the origin (step c in FIG. 8). Thereafter, the Y-direction position measurement value of the reticle 1 is the same as the measurement value of the laser interferometer 31. A value obtained by adding the measurement values of the laser interferometer 81 is used. Assuming that the measurement value of the laser interferometer 31 is Yi1 and the measurement value of the laser interferometer 81 is YS1, the measurement value Y of the reticle 1 in the Y direction is

[0045]

[Equation 2] Becomes K is a constant.

Next, according to the measured values of the laser interferometer 31 and the laser interferometer 81, the drive control means 103 moves the reticle stage 4 to the wafer alignment marks 43 and 47 on the reticle 1 and the wafer alignment observation microscopes 7 and 8 are arranged.
A predetermined amount is driven in the Y direction so that it falls within the field of view. Further, the wafer stage 5 is driven in the X and Y directions by a predetermined amount so that the wafer alignment marks 44 and 48 on the wafer 3 are within the field of view of the wafer alignment observation microscopes 7 and 8. Wafer alignment marks 48, 4 on the wafer 3 with respect to the wafer alignment marks 43 or 47 on the reticle 1.
The relative positional deviation of No. 4 is photoelectrically observed by the wafer alignment observation microscopes 7 and 8 and the obtained signal is processed by the mark detecting means 101, and the relative positional relationship information of each is sent to the arithmetic processing means 102. This processing is executed for several shots, and the relative positional relationship information obtained from each shot is statistically processed, and the pattern area 21 on the reticle 1 and the transfer area 22 of each shot already exposed on the wafer 3 are Obtain the XY coordinates of the center of each shot so that they match (see FIG. 8).
Step d).

Next, the drive control means 103 drives the reticle stage 4 to the exposure start position according to the measured values of the laser interferometer 31 and the laser interferometer 81. Similarly, the drive control means 1 according to the measurement values of the laser interferometers 35 and 37.
The wafer stage 5 is also driven by 03 to an exposure start position which is deviated by a predetermined amount from the XY coordinates of the center of each shot (step e in FIG. 8).

Consider a case where a positional deviation of the reticle 1 occurs as shown in FIG. 7 after the start of scanning exposure. Laser interferometers 81 and 82 measuring the position of the reticle 1 in the Y direction
Let YS1 and YS2 be the measured values, Yi1o be the drive target position of the reticle stage 4, and X1 be the measured value of the laser interferometer 83 that measures the position of the reticle 1 in the X direction.
The mounting interval of the laser interferometers 81 and 82 is L,

[0049]

(Equation 3) Becomes Therefore, the inclination of the reticle 1 can be corrected by first driving the θ drive mechanism of the reticle stage 4 by Δθ. Next, the measurement is performed again, the shift amount is calculated, and the X drive shift of the reticle 1 can be corrected by driving the X drive mechanism of the reticle stage 4 by ΔX. Furthermore Y
The deviation in the direction can be corrected by driving the Y driving mechanism of the reticle stage 4 by ΔY (step f in FIG. 8).

Although the deviation correction driving of the reticle 1 is always executed, the exposure accuracy is affected in the case of a large deviation. Therefore, the deviation occurrence detection means of the reticle 1 is XY
The measured value of θ is always observed, and it is judged that the abnormal deviation occurs only when the set tolerance is deviated. The tolerance value and the like are as described in the first embodiment, and the tolerance values Xt, Yt, and θt in the XYθ directions are 4 respectively.
It is desirable that the values are about 0 nm, 40 nm, and 0.4 ppm (step g in FIG. 8).

Information storage of the abnormal exposure shot, display on the display device, and the like are as described in the first embodiment (step h in FIG. 8).

In the second embodiment, laser interferometers 81, 82, 83 for measuring the position of the reticle are used.
Since the optical path length is substantially constant, a high degree of parallelism between the pattern area 21 and the mirror surface portion 61 of the reticle end surface is not required.

Laser interferometer 8 used in the second embodiment
In order to realize the function equivalent to 1, 82, 83,
It is also possible to use the position measurement sensor such as the electrostatic capacity sensor used for the measurement in the X direction of the embodiment. An example of such a configuration is shown in FIGS. In this case, the reticle alignment marks 41 and 45 and the reticle reference marks 42 and 46
Position measurement sensors 51, 52 at the end of alignment with
The measured value of 53 may be stored as an initial value and used for subsequent processing.

As the position measuring sensors 51, 52 and 53 used in the first and second embodiments, a light projecting element and a light receiving element are arranged so as to sandwich the reticle 1, and the optical path is blocked by the reticle 1. A so-called transmissive sensor that utilizes the fact that the output of the light receiving element changes due to the above may be used.

It is also possible to use a laser interferometer as the position measuring sensor 51 in the X direction of the first embodiment.

(Third Embodiment) The third embodiment of the present invention will be described in detail below. 11 and 12 show the structure of a scanning exposure apparatus according to the third embodiment of the present invention. FIG.
5 shows the flow.

In FIGS. 11 and 12, the reticle 1 on which the original image is drawn has a length measuring means 104 and a drive control means 103.
The reticle stage 4 is mounted on a reticle stage 4 which is driven and controlled in the XYθ directions by the reticle stage 4, and is supported by an apparatus main body (not shown). The length measuring unit 104 measures the position in the scanning direction (Y direction in the drawing) by the laser interferometer 31. The wafer 3 which is a photosensitive substrate is a laser interferometer 3
5, 37 and the drive control means 103 are mounted on the wafer stage 5 which is driven and controlled in the XYθ directions, and the wafer stage 5 is supported by an apparatus body (not shown). The reticle 1 and the wafer 3 are placed at optically conjugate positions via the projection optical system 2, and slit exposure light 6 extending in the X direction from the illumination system (not shown) is emitted by the reticle 1.
Is illuminated, and an image is formed on the wafer 3 in a size proportional to the projection magnification of the projection exposure system 2. The scanning exposure is performed by moving both the reticle stage 4 and the wafer stage 5 in the Y direction at a speed ratio according to the optical magnification with respect to the slit-shaped exposure light 6 to scan the reticle 1 and the wafer 3. The entire surface of the pattern area 21 on the wafer 3 is transferred to the transfer area 22 on the wafer 3.

Details of this embodiment will be described with reference to the flow chart of FIG. First, prior to placing the reticle 1 on the reticle stage 4, the reticle stage 4 is driven to the reference position of the apparatus main body to perform alignment, that is, so-called origin position driving is executed. When the reticle 1 is mounted on the reticle stage 4 by a transport device (not shown) after the origin position drive is stopped and the reticle stage 4 is stationary, the reticle alignment marks 41 and 45 on the reticle 1 and the reticle alignment marks 41 and 45 are fixed. Both of the reticle reference marks 42 and 46 on the stage 4 are within the field of view of the reticle alignment observation microscopes 9 and 10 (FIG. 15).
Step a).

In this state, the relative displacement of the reticle reference marks 42 and 46 on the reticle stage with respect to the reticle alignment mark 41 or 45 on the reticle 1 is measured by the reticle alignment observation microscopes 9 and 1.
The signal obtained is observed photoelectrically at 0 and the obtained signal is detected by the mark detecting means 1.
01 and sends the relative positional relationship information to the arithmetic processing means 102.

Based on this information, the reticle 1 is moved in the XYθ directions, and the alignment is performed so that the relative positional deviations between them are eliminated. By the above procedure, the reticle 1 is correctly positioned on the reticle stage 4 (step b in FIG. 15).

In this embodiment, the reticle stage 4
Is driven to the scanning exposure start position or the scanning exposure end position (the reticle normally reciprocates, so these two positions are the same), the reticle alignment is within the visual field of the reticle alignment observation microscopes 9 and 10. Mark 7
1, 73 and the reticle reference marks 72, 74, or the reticle alignment marks 75, 77 and the reticle reference marks 76, 78 are arranged so as to enter.

First, the reticle alignment mark 71,
The reticle stage 4 is driven to the 73 side, and the reticle alignment mark 71 and the reticle reference mark 72, and the reticle alignment mark 73 and the reticle reference mark 7 are driven.
Each of the relative positional deviations of No. 4 is photoelectrically observed by the reticle alignment observation microscopes 9 and 10, and the obtained signals are processed by the mark detecting unit 101 to calculate the relative positional relationship information of each of them. Send to. This deviation is XYθ
The difference amounts are respectively stored (step c in FIG. 15). The amount of this deviation is Z10XYθ.

Similarly, the reticle alignment mark 75,
The reticle stage 4 is driven to the 77 side, and the relative positional deviations of the reticle alignment mark 75 and the reticle reference mark 6 and the reticle alignment mark 77 and the reticle reference mark 8 are stored as XYθ deviation amounts ( Figure 15 step d). This displacement amount is set to Z20XYθ Next, the alignment between the reticle 1 and the wafer 3 is executed as in the first and second embodiments (step e in FIG. 15).

Next, the drive control means 103 drives the reticle stage 4 to the exposure start position according to the measurement value of the laser interferometer 31. Similarly, laser interferometers 35 and 37
The wafer stage 5 is also driven by the drive control unit 103 to an exposure start position which is deviated by a predetermined amount from the XY coordinates of the center of each shot according to the measured value of (step f in FIG.

One scanning exposure (for example, forward path) is completed,
At the time when the reticle stage 4 is stopped ((b) in FIG. 12 and t1 in FIG. 13), the amount of deviation between the reticle alignment marks 71, 73 and the reticle reference marks 72, 74 is measured. This amount of deviation is Z11XYθ.

The difference between this deviation amount and the initial deviation amount Z10XYθ obtained in the step c of FIG.
The absolute value of the difference between the θ components is compared with a preset tolerance value, and if it exceeds the tolerance value, correction drive is executed (step g in FIG. 15). A shot that deviates from the set tolerance is judged as an abnormal shift. The tolerance value and the like are as described in the first embodiment,
The tolerance values in the XYθ directions are 40 nm and 40, respectively.
When the correction drive, which is desirable to have a value of about 0.4 nm for nm, is completed, the next scanning exposure (for example, the return pass) is executed. At the time when the scanning exposure is completed and the reticle stage 4 is stopped ((c) in FIG. 12 and t2 in FIG. 13), the amount of deviation between the reticle alignment marks 75, 77 and the reticle reference marks 76, 78 is measured. The amount of this deviation is Z21XYθ.

The difference between this deviation amount and the initial deviation amount Z20XYθ obtained in the step d of FIG.
The absolute value of the difference of the θ component is compared with a preset tolerance value, and if it exceeds the tolerance value, correction driving is executed (step h in FIG. 15).

Step g and step h in FIG. 15 are repeated to perform exposure over the entire surface of the wafer.

Information storage of the abnormal exposure shot, display on the display device, and the like are as described in the first embodiment (step i in FIG. 15).

Next, the relationship between the size of the pattern area 21 on the reticle 1 and the reticle alignment marks 71, 73, 75, 77 that can be observed at the scanning exposure start or end position will be described.

As shown in FIG. 13, the scanning distance from the end of exposure in the pattern area 21 to the stop of the reticle stage 4 is constant regardless of the size of the pattern area 21. Therefore, if the pattern area 21 becomes narrower, the total traveling distance of the reticle stage 4 during scanning exposure becomes shorter.

Therefore, the reticle alignment mark 7
As shown in FIG. 14, the arrangement of 1, 73, 75, 77 on the reticle 1 is preferably changed to an optimum position depending on the size of the pattern area 21 so that the pattern can be observed at the scanning exposure start or end position.

With this, it is possible to detect the occurrence or non-occurrence of the reticle shift without reducing the throughput.

Next, an embodiment of a device manufacturing method using the above-described scanning type exposure apparatus and method will be described.
FIG. 17 shows a flow of manufacturing minute devices (semiconductor chips such as IC and LSI, liquid crystal panels, CCDs, thin film magnetic heads, micromachines, etc.). In step 1 (circuit design), the circuit of the semiconductor device is designed. Step 2
In (mask production), a mask on which a designed circuit pattern is formed is produced. On the other hand, in step 3 (wafer manufacturing), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the mask and wafer prepared above. The next step 5 (assembly) is called a post-process, which is a process of forming a semiconductor chip using the wafer manufactured in step 4, and includes an assembly process (dicing, bonding), a packaging process (chip encapsulation), etc. including. Step 6
In (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 18 shows a detailed flow of the wafer process. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted in the wafer. In step 15 (resist processing), a photosensitive agent is applied to the wafer.
In step 16 (exposure), the circuit pattern of the mask is printed and exposed on the wafer by the above-described exposure apparatus.
Step 17 (development) develops the exposed wafer.
In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), the resist that is no longer needed after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

By using the manufacturing method of this embodiment, a highly integrated semiconductor device, which has been difficult to manufacture in the past, can be manufactured at low cost.

[0077]

As described above, according to the present invention, the scanning exposure is performed by constantly measuring the position of the reticle suction-fixed on the reticle stage during the scanning exposure, or at the scanning exposure start position or the scanning exposure end position. By detecting and correcting the misalignment between the reticle stage and the reticle, the number of abnormal exposure shots due to the misalignment of the reticle can be minimized, and the device pattern on the reticle can be accurately transferred onto the wafer. It has become possible.

Further, it is possible to prevent the occurrence of defective devices by detecting the occurrence of the reticle position deviation during scanning exposure, storing the shot information in which the deviation occurred, and transmitting this information to the operator. It was

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention.

FIG. 2 is a top view of the reticle stage according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of reticle misalignment in the first embodiment of the present invention.

FIG. 4 is a flow chart of the first embodiment of the present invention.

FIG. 5 is a schematic view of a main part of a second embodiment of the present invention.

FIG. 6 is a top view of a reticle stage according to a second embodiment of the present invention.

FIG. 7 is an explanatory diagram of reticle misalignment in the second embodiment of the present invention.

FIG. 8 is a flow chart of a second embodiment of the present invention.

FIG. 9 is a schematic view of a main part when a position measuring sensor is used in the second embodiment of the present invention.

FIG. 10 is a top view of the reticle stage when a position measuring sensor is used in the second embodiment of the present invention.

FIG. 11 is a schematic view of a main part of a third embodiment of the present invention.

FIG. 12 is a top view of a reticle stage according to a third embodiment of the present invention.

FIG. 13 is a timing chart of scanning exposure in the third embodiment of the present invention.

FIG. 14 is a top view of the reticle stage when the pattern area of the third embodiment of the present invention is narrow.

FIG. 15 is a flow chart of the third embodiment of the present invention.

FIG. 16 is a diagram showing a display example of a reticle abnormal displacement occurrence shot according to the present invention.

FIG. 17 is a semiconductor device manufacturing flow.

FIG. 18 is an explanatory diagram for a wafer process.

FIG. 19 is a schematic view of a main part of a conventional example.

[Explanation of symbols]

1: reticle, 2: projection optical system, 3: wafer, 4: reticle stage, 5: wafer stage, 6: exposure light, 7,
8: Observation microscope for wafer alignment, 9, 10: Observation microscope for reticle alignment, 21: Pattern area, 2
2: transfer area, 31, 32: laser interferometer (for reticle position measurement), 33, 34: laser interferometer beam (for reticle position measurement), 35, 37: laser interferometer (for wafer position measurement), 36, 38: Laser interferometer beam (for wafer position measurement), 41, 45, 71, 73, 7
5, 77: reticle alignment mark, 42, 46,
72, 74, 76, 78: reticle reference mark, 43,
47: Wafer alignment mark (reticle side), 4
4, 48: Wafer alignment mark (wafer side), 5
1: Position measurement sensor (X side), 52, 53: Position measurement sensor (Y side), 61: Mirror surface part for measurement by laser interferometer, 81, 82, 83: Laser interferometer, 1
01: mark detecting means, 102: arithmetic processing means, 10
3: Drive control means, 104: Length measuring means.

Claims (19)

[Claims] 1. A first movable stage that mounts and moves a first object, and a second movable stage that mounts and moves a second object, and projects the first and second movable stages. In a scanning type exposure apparatus that scans in synchronization with an optical system and projects a pattern on the first object onto the second object via the projection optical system, the scanning exposure apparatus is substantially fixed on the first movable stage. Position measuring means for constantly measuring the position of the first object during scanning exposure, and position deviation detection for detecting occurrence of deviation between the first movable stage and the first object based on an output signal from the position measuring means. A scanning type exposure apparatus comprising: a means and a correction drive means for constantly correcting the position of the first object based on the generated deviation amount during scanning exposure. 2. The position measuring means sets at least one end surface of the first object into a mirror surface state, and irradiates the mirror surface portion with a light beam of a laser interferometer to measure the position of the first object. The scanning exposure apparatus according to claim 1, wherein the scanning exposure apparatus is configured as described above. 3. The position measuring means is configured to measure a deviation amount of the first object in the scanning direction of the first movable stage, a deviation amount in a non-scanning direction, and a deviation amount in a rotation direction. The scanning exposure apparatus according to claim 1, wherein: 4. The position measurement means measures the value of a laser interferometer that measures the position of the first movable stage and the position measurement that measures the position of the first object placed on the first movable stage. The scanning exposure apparatus according to claim 1, wherein a value obtained by adding the measurement value of the sensor is used as the position of the first object. 5. The scanning exposure apparatus according to claim 4, wherein a laser interferometer is used as a position measuring sensor which is mounted on the first movable stage and measures the position of the first object. 6. The position deviation detecting means independently permits the deviation amount of the first object in the scanning direction of the first movable stage, the deviation amount in the non-scanning direction, and the deviation amount in the rotation direction. 2. The scanning exposure apparatus according to claim 1, wherein the value can be set, and when the deviation amount is larger than an allowable value, it is recognized that an abnormal deviation has occurred. 7. A device manufacturing method using the scanning exposure apparatus according to claim 1. Description: 8. A first movable stage on which a first object is placed and moves, and a second movable stage on which a second object is placed and moves are scanned in synchronization with a projection optical system, and the projection is performed. In a scanning exposure method of projecting a pattern on the first object onto the second object via an optical system, the position of the first object substantially fixed on the first movable stage is constantly measured during the scanning exposure. And a position deviation detecting step of detecting that a deviation between the first movable stage and the first object has occurred based on the position signal obtained in the position measuring step; The first
And a correction driving step for constantly correcting the position of the object during scanning exposure. 9. A method of manufacturing a device, wherein the scanning exposure method according to claim 8 is used. 10. A first movable stage that mounts and moves a first object, and a second movable stage that mounts and moves a second object, and projects the first and second movable stages. In a scanning type exposure apparatus that scans in synchronization with an optical system and projects a pattern on the first object onto a second object in the previous period via the projection optical system, the scanning exposure apparatus is substantially fixed on the first movable stage. Position measuring means capable of measuring the position of the first object when the first movable stage is positioned at the scanning exposure start position or the scanning exposure end position, and the first movable stage and the first movable stage based on an output signal from the position measuring means. Positional deviation detecting means for detecting occurrence of deviation between the first objects, and correction driving means for correcting the position of the first object based on the amount of deviation occurring before the start of scanning exposure or after the end of scanning exposure. A scanning type exposure apparatus comprising: 11. The position measuring means arranges a plurality of marks for aligning the first object on the first object so that the marks can be measured at the scanning exposure start position and the scanning exposure end position. The scanning type exposure apparatus according to claim 10. 12. The scanning exposure according to claim 11, wherein the position of the mark for aligning the first object is changed to an optimum position in accordance with an exposure range on the first object. apparatus. 13. A device manufacturing method using the scanning exposure apparatus according to claim 10. 14. A first movable stage on which a first object is placed and moves, and a second movable stage on which a second object is placed and moves are scanned in synchronization with a projection optical system, and the projection is performed. In a scanning exposure method of projecting a pattern on the first object onto the second object via an optical system, the position of the first object substantially fixed on the first movable stage is set to the first movable stage. A position measurement step that enables measurement when is located at the scanning exposure start position or the scanning exposure end position, and a deviation between the first movable stage and the first object is generated by the position signal obtained in the position measurement step. And a correction driving step of correcting the position of the first object based on the amount of deviation that has occurred before or after the scanning exposure starts. Scanning exposure method. 15. A method for manufacturing a device, wherein the scanning exposure apparatus according to claim 14 is used. 16. A projection optical system, comprising: a first movable stage that carries a first object and moves, and a second movable stage that carries a second object and moves. In the scanning type exposure apparatus, which scans in synchronization with, and projects the pattern on the first object onto the second object via the projection optical system, the first exposure device that is substantially fixed on the first movable stage. When a displacement of one object with respect to a scan drive target position occurs, a storage unit that stores the exposure shot information in which the displacement occurs and a transmission unit that transmits the stored exposure shot information to an operator are provided. Scanning exposure device. 17. A method of manufacturing a device, wherein the scanning exposure apparatus according to claim 16 is used. 18. A first movable stage on which a first object is placed and moves, and a second movable stage on which a second object is placed and moves are scanned in synchronization with a projection optical system and the projection is performed. In a scanning exposure method of projecting a pattern on the first object onto the second object via an optical system, a positional deviation of the first object, which is substantially fixed on the first movable stage, from a scan drive target position. When occurs,
A scanning type exposure method comprising: a storage step of storing exposure shot information in which the positional deviation has occurred, and a transmission step of transmitting the stored exposure shot information to an operator. 19. A device manufacturing method using the scanning exposure method according to claim 18.