JP2000182930A - Method and device for exposure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow stacking at higher precision when mix-and-match is performed between devices for step-and-scan exposure. SOLUTION: Related to an exposure method using mix-and-match method while a plurality of step-and-scan type exposure devices are used, a second exposure is performed scanning in the direction orthogonal to the scan direction at first exposure. Thus, when mix-and-match is performed between devices for step-and-scan exposure, stacking at higher precision is allowed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an exposure method and an exposure apparatus, and more particularly to an exposure method and an exposure apparatus of a step-and-scan type.

[0002]

2. Description of the Related Art As the degree of integration of a semiconductor device increases, the circuit pattern of an LSI element constituting the semiconductor device becomes finer. In order to make the pattern finer, it is required not only to reduce the line width but also to improve the dimensional accuracy and positional accuracy of the pattern. Many technologies have been developed to meet these demands. Among them, for example, the exposure technology using X-ray is promising as the next generation technology of the exposure technology using ultraviolet rays currently used. Have been watched.

The X-ray exposure technology that is currently being developed uses synchrotron radiation, and is applied to a stepper through a mirror for expanding the exposure area, a beam line composed of a Be thin film serving as a vacuum partition, and the like. The exposure system uses the guided light, and performs one-to-one proximity exposure using a 1: 1 mask. In many cases, by moving the above-described mirror, the exposure area is enlarged, and the exposure area is sequentially moved on the substrate to be exposed, using a so-called step-and-scan exposure method. I have.

On the other hand, the circuit configuration of a semiconductor device is increasing in complexity, and at present, 20 or more exposure steps may be required to complete one product. It is rare that a fine pattern is required, and it is not necessary to process all the exposure steps using a very expensive exposure apparatus at the most advanced state, and there is a high possibility that wasteful costs will be incurred. For this reason, a so-called mix-and-match method that uses an expensive state-of-the-art device for forming a fine pattern and an inexpensive device for forming a slightly loose pattern is generally used.

[0005]

However, when exposure is performed a plurality of times using the above-described step-and-scan type exposure apparatus, the following problem occurs. That is,
In the case of using such a step-and-scan type exposure apparatus, the exposure transfer position often deviates from the ideal position due to an inherent error of the stage, fluctuation of the stage, distortion inherent to the optical system, and the like. When exposing and transferring a different layer in a subsequent exposure step on a base formed with a deviation in the previous exposure step, a superposition error may occur if the deviation of the base is ignored. Will increase.

In particular, when separate step-and-scan type exposure apparatuses are used for the first exposure step and the second exposure step, the deviation of the exposure transfer position from the ideal position in the first exposure step greatly affects. As a result, there is a problem that the overlay error in the subsequent exposure process is significantly increased.

[0007] It has also been found that even when the above-mentioned mix-and-match method is performed, such an overlay error becomes large and a characteristic tendency is observed.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an exposure method and an exposure apparatus capable of performing more accurate overlay.

[0009]

(Structure) In order to solve the above-mentioned problems, a first aspect of the present invention is to provide a step-and-
Performing a first exposure using a scan type exposure apparatus, and using a step-and-scan type exposure apparatus, performing a scan in a direction orthogonal to the scan direction at the time of the first exposure. And performing an exposure step.

A second aspect of the present invention is a step of performing a first exposure using a step-and-scan type exposure apparatus, and a step of performing the first exposure using a step-and-scan type exposure apparatus. Performing a second exposure while performing scanning in a direction parallel to the scanning direction at the time of exposure.

Further, a third aspect of the present invention is a step
Performing a first exposure using an and scan type exposure apparatus, detecting a part of the pattern formed by the first exposure, and performing the first exposure based on the detected signal. Comparing the deviation in the direction perpendicular to the scanning direction and the deviation in the parallel direction at the time of the scanning, and using a step-and-scan type exposure apparatus, the direction orthogonal to the direction of the larger deviation in the two directions. Performing a second exposure while performing scanning.

In the first, second and third aspects of the present invention described above, it is desirable to have the following configuration. (1) A part of the pattern formed by the first exposure is detected, and the second exposure is performed while absorbing a shift of the first exposure based on the detected signal.

(2) A part of the pattern formed by the first exposure is detected, and the second exposure is performed while controlling at least one of a scan speed, a magnification, and a stage position based on the detected signal. To do.

(3) The first exposure and the second exposure are exposures using a mix-and-match method. In a fourth aspect of the present invention, a step of performing a first exposure to form a pattern, a step of detecting a part of the formed pattern, and a step of detecting a deviation of the pattern based on a detected signal. A step of determining the largest direction, and a step of performing the second exposure while scanning in a direction orthogonal to the direction in which the deviation is the largest using a step-and-scan type exposure apparatus. An exposure method is provided.

In the fourth aspect of the present invention, it is desirable to have the following configuration. (1) Detecting a part of the formed pattern and performing the second exposure while absorbing a shift of the pattern based on a detected signal.

(2) A part of the formed pattern is detected, and scanning speed, magnification,
Performing the second exposure while controlling at least one of the stage positions.

(3) The first exposure and the second exposure are exposures using a mix-and-match method. A fifth aspect of the present invention is a step-and-scan type exposure apparatus including a rotatable sample stage on which a sample to be exposed is mounted, and an exposure optical system for controlling exposure of the sample to be exposed. Detecting means for detecting a part of the pattern on the sample to be exposed formed by the first exposure; and a scanning direction at the time of the first exposure based on a signal detected by the detecting means. Comparing means for comparing the displacement in the orthogonal direction and the displacement in the parallel direction, and performing a scan in the direction perpendicular to the direction of the larger displacement among the displacements in both directions based on a comparison result of the displacement by the comparing means. Control means for adjusting the rotation of the sample stage to control the orientation of the sample to be exposed on which the first exposure has been performed, in order to enable the exposure to be performed. Provide equipment.

Still further, according to a sixth aspect of the present invention, there is provided a step comprising a rotatable sample stage on which a sample to be exposed on which a pattern is formed is mounted, and an exposure optical system for controlling exposure of the sample to be exposed. An and-scan type exposure apparatus, comprising: a detection unit for detecting a part of a pattern on the sample to be exposed; and a direction in which the pattern displacement is greatest based on a signal detected by the detection unit. The determining means for determining, based on the determination result by the determining means, to adjust the rotation of the sample stage so that it is possible to perform exposure by scanning in a direction orthogonal to the direction in which the deviation is the largest. An exposure apparatus comprising: a control unit configured to control a direction of the sample to be exposed.

(Operation) According to the first aspect of the present invention, when performing the step-and-scan type exposure, the scanning direction is made substantially orthogonal between the first exposure and the second exposure. The influence of an error caused by the inherent distortion of the optical system can be extremely reduced, and high-accuracy superposition can be performed. In particular, when performing mix-and-match between different step-and-scan apparatuses, the effect of the superposition is great.

According to a second aspect of the present invention, there is provided a method comprising:
In the case of performing the AND-scan type exposure, the scan direction is made substantially parallel (identical) between the first exposure and the second exposure, so that the influence of the inherent error and fluctuation of the stage is extremely reduced. This enables high-accuracy superposition. In particular, when performing mix-and-match between different step-and-scan apparatuses, the effect of the superposition is great.

Further, according to the third aspect of the present invention, the displacement of the background caused in the first exposure is detected in advance before performing the second exposure step, and based on the detected signal, the displacement of the second exposure step is detected. It is determined whether the scanning is performed in a direction parallel to the scanning direction of the first exposure step or in a direction orthogonal to the scanning direction.
Therefore, regardless of whether the deviation in the direction orthogonal to the scan direction in the first exposure step is large or the deviation in the parallel direction is large, the second exposure step is performed with smooth and high-precision alignment in any case. It is possible.

Still further, according to the fourth aspect of the present invention, a shift of a pattern formed by performing the first exposure is detected in advance before performing the second exposure step, and based on the detected signal, The direction in which the pattern shift is greatest is determined. By using a step-and-scan type exposure apparatus and performing scanning in a direction orthogonal to the direction having the largest deviation, the second exposure step can be performed with smooth and high-precision alignment. It is possible. Further, according to the fifth and sixth aspects of the present invention, it is possible to provide an exposure apparatus capable of performing the second exposure step with smooth and high-precision alignment similarly to the above operation.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the exposure method and the exposure apparatus according to the present invention will be described in detail with reference to the drawings. (First Embodiment) FIG. 1 is a flowchart showing the steps of a first embodiment of the present invention. FIG. 2 is a plan view showing a shift in exposure on the substrate to be exposed. FIG. 2B is a plan view showing a substrate to be exposed (wafer), and FIG. 2A is a plan view showing a shift in exposure in one chip.

As shown in FIG. 1, first, a resist is applied to a substrate (wafer) 1 shown in FIG. 2 and heat treatment is performed before exposure. Next, a first exposure process in the first scan direction 4 is performed using a first step-and-scan type exposure apparatus using ultraviolet light as a light source. Reference numeral 2 denotes a chip, which indicates an exposure unit. Although this first step-and-scan type exposure apparatus is not shown, its operation mechanism is as follows.

That is, the first step-and-scan type exposure apparatus uses a KrF excimer laser as exposure light. Ultraviolet light having a wavelength of 248 nm generated by the KrF excimer laser light source enters the mask through the illumination optical system, forms an image of the mask on the substrate to be exposed through the imaging optical system, and performs exposure. The imaging area of the imaging optical system is smaller than the chip size, but is configured to expand the exposure area by simultaneously scanning the mask and the substrate to be exposed.

Specifically, the mask stage on which the mask is mounted and the wafer stage on which the substrate to be exposed is mounted
The respective stages are connected to a mask stage drive system and a wafer stage drive system, and drive control of each stage is performed based on information obtained from a stage position detection mechanism and an alignment optical system included in each stage drive system. As a result, the exposure area is enlarged, and so-called step-and-scan type exposure in which the exposure area moves on the substrate to be exposed is performed.

After performing the first exposure step described above, FIG.
As shown in (1), heat treatment and development after exposure are completed, and thereafter, the wafer 1 undergoes processes such as etching, cleaning, and film formation. Next, as shown in FIG. 1, after a resist application and a heat treatment before exposure are performed again, a second step-and-scan exposure apparatus using X-rays as a light source is used to perform a first scanning direction. A second exposure step is performed by scanning in a direction perpendicular to the direction of Step 4.

Here, the second step-and-scan type exposure apparatus 100 uses synchrotron radiation (SOR) as shown in FIG. Synchrotron radiation emitted from the synchrotron ring 101 is incident on a beam line 103 made of a Be thin film or the like serving as a vacuum partition from an X-ray extraction port 102. Further, the synchrotron radiation light includes an aperture 104 for limiting an X-ray area, an X-ray reflection mirror 105 for expanding an exposure area, an X-ray detector 107, an X-ray shutter 108,
After passing through the separation window 106 and the X-ray intensity distribution adjusting means 123, X
The light enters the line exposure chamber 109. An X-ray reflection mirror driving system 111 is connected to the X-ray reflection mirror 105, and the attitude and the like of the X-ray reflection mirror 105 are controlled by the X-ray reflection mirror control system 110 via the driving system 111.

On the other hand, in the X-ray exposure chamber 109, the X-ray mask 112 is held by the mask stage 113, and the substrate to be exposed 114 is held by the wafer stage 115. The mask stage driving system 116 and the wafer stage driving system 1
The mask stage control system 118 and the wafer stage control system 119 are connected to these drive systems.

Reference numeral 120 denotes an alignment optical system. The optical system 120 uses the alignment mark in the X-ray mask 112 and the alignment mark of the exposure area on the substrate 114 to be positioned in accordance with the position of the exposure area in real time. A signal is detected. This signal is transmitted to the alignment control system 121, and pattern position information of the X-ray mask 112 and pattern position information of the substrate 114 to be exposed are formed in the alignment control system 121 based on the signal.

The position information is transmitted to an X-ray reflection mirror control system 110, a mask stage control system 118, a wafer stage control system 119, etc., and the drive control of the X-ray reflection mirror 105, the mask stage 113, and the wafer stage 115 is performed. As a result, the alignment operation and the exposure process between the inside of the X-ray mask 112 and the substrate to be exposed 114 are sequentially performed.

That is, a one-to-one proximity exposure is performed using an equal-magnification mask as the X-ray mask 112, and the exposure area is enlarged by moving the X-ray reflection mirror 105. A so-called step-and-scan type exposure method, which moves sequentially on the top, is performed. A gap sensor 122 sets a gap between the X-ray mask 112 and the substrate 114 to be exposed.

Next, as shown in FIG. 1, after the heat treatment and the development after the exposure are completed again, the wafer 1 is sent to the next exposure step through the steps of etching, cleaning or film formation. To go.

The most significant feature of this embodiment is that in the first exposure step using ultraviolet light and the second exposure step using X-rays, the scanning directions of exposure are substantially orthogonal to each other.

As shown in FIGS. 2A and 3A,
When exposure is performed using a step-and-scan type exposure apparatus, the exposure transfer position often deviates from the ideal position due to a stage-specific error and a distortion inherent to the optical system. In the case of a primary distortion such as a mere magnification error, it is possible to correct the exposure transfer position irrespective of the scanning direction by performing the magnification correction. Higher order distortions exist.

When exposure transfer to another layer is performed in the second exposure step on the base formed with a shift in the first exposure step as described above, if the shift in the base is ignored, Although the registration error increases, if the displacement of the base can be detected and the subsequent exposure transfer can be performed in accordance with the detection, the increase in the registration error can be suppressed.

In the present embodiment, step-and-
As a feature of the scanning type exposure apparatus, the region 3a to be exposed and transferred at the same time has a strip shape. Therefore, FIG.
As shown in FIG. 3A and FIG. 3A, the above-mentioned higher-order distortion with respect to the ideal exposure region 6 is such that the deviation from the central axis becomes large as in the exposure region 5 and the longitudinal direction of the strip. (R) Appears mainly depending on 7. At this time, the magnitude of the distortion in the r direction 7 is δ _r and s perpendicular to the longitudinal direction of the strip.
Direction size of the distortion of the (first scanning direction) 4 as [delta] _s, shown in the characteristic diagram shown in FIG. 3 (b) the relationship between r and [delta] _r and [delta] _s. The relationship (ratio) between δ _r and δ _s also changes with the change in _r, and it can be seen that there is a second-order or higher-order distortion that cannot be ignored.

FIG. 4 is a plan view showing the exposure method of the present embodiment. As shown in FIG. 4, in the present embodiment, in the second exposure step, a region to be exposed and transferred
As b, scanning is performed in the direction 10 orthogonal to the longitudinal direction of the strip-shaped region 3b. Further, the scanning direction 10 in the second exposure step is set to the same direction as the longitudinal direction 7 of the strip-shaped exposure area 3a in the first exposure step. In such a configuration, the position of the base pattern is
Then, by finely adjusting the scan speed or the stage position based on the detected signal, the position of the strip-shaped exposure region 3b on the substrate 1 to be exposed is corrected, and the exposure region 9 is transferred. By the second exposure step, an area substantially the same as the exposure area 5 in the first exposure step can be exposed and transferred, and high-order distortion can be corrected.

More specifically, the substrate 1 to be exposed
By scanning the stage, the mark position on the substrate 1 to be exposed is detected and stored, and in actual exposure, a position is adjusted based on the stored mark position. Immediately after, the mark position and focus of the area to be exposed are detected, and the method of performing exposure while applying feedback is performed. The mark position on the substrate 1 to be exposed is detected for each chip 2 and fine adjustment of the alignment is performed for each chip. An exposure method or the like can be applied.

As described above, when correcting second-order or higher-order distortion, the effect cannot be obtained unless the first-order magnification correction with a lower order and a large error component is not sufficiently performed. It may not be able to fully demonstrate. Usually step-and-
In a scanning type exposure apparatus, in the direction perpendicular to the scanning direction, the magnification is corrected by finely adjusting the reduction ratio of the optical system, and in the direction parallel to the scanning direction, the mask or the substrate stage to be exposed is scanned. The magnification can be corrected by finely adjusting the speed.

However, when the substrate to be exposed expands and contracts, there is a non-uniform component in the surface due to non-uniformity of the process and unevenness of the flatness of the stage surface on which the substrate to be exposed is mounted. There is. In order to cope with such non-uniform component correction, it is desirable that the magnification correction is not a method of performing uniform correction over the entire surface of the substrate to be exposed, but a method of performing fine adjustment during exposure.

That is, in conjunction with the previous embodiment, the second
In the exposing step, the mark formed in the first exposing step is detected, and based on the detected signal, scanning is performed in a direction orthogonal to the scanning direction in the first exposing step. By performing the exposure while controlling the magnification, the stage position, and the stage position, it is possible to perform high-accuracy alignment.

In contrast to the previous embodiment, when the second exposure step using ultraviolet rays is performed after the first exposure step using X-rays, the influence of distortion of the optical system is relatively small. A pattern which is greatly affected by the distortion of the optical system is superimposed on the base pattern. Even in such a case, the present invention can be effectively applied. That is, the distortion generated in the second exposure step may be measured in advance, and correction may be made at the time of the first exposure based on the data.

Further, the present invention is not limited to the combination of the ultraviolet exposure apparatus and the X-ray exposure apparatus as the combination of the exposure apparatuses, but may be used between the ultraviolet exposure apparatuses of different wavelengths, or between these exposure apparatuses and the electron beam batch transfer exposure apparatus. It is possible to use a combination between various exposure apparatuses using the step-and-scan method, such as a combination.

(Second Embodiment) FIG. 5 is a flowchart showing steps of a second embodiment of the present invention. FIG. 6 is a plan view showing a shift in exposure on the substrate to be exposed. FIG.
FIG. 6B is a plan view showing a substrate to be exposed (wafer), and FIG.
(A) is a plan view showing a shift of exposure in one chip.

As shown in FIG. 5, first, a resist is applied to the substrate (wafer) 11 shown in FIG. 6 and heat treatment is performed before exposure. Next, a first exposure process in the first scan direction 14 is performed using a first step-and-scan type exposure apparatus using X-rays as a light source. This first
Is the first step-and-scan type exposure apparatus
The embodiment shown in FIG. In addition,
In FIG. 6, reference numeral 12 denotes a chip, which indicates an exposure unit.

After performing the above-described first exposure step, FIG.
As shown in (1), heat treatment and development after exposure are completed, and thereafter, the wafer 1 undergoes processes such as etching, cleaning, and film formation. Next, as shown in FIG. 5, after the application of the resist and the heat treatment before exposure are performed again, the first step-and-scan type exposure apparatus using ultraviolet light as a light source is used for the first step.
Second scanning by scanning in a direction parallel to the scanning direction 14
Is performed. As the second step-and-scan type exposure apparatus, the same one as in the first embodiment is used.

Next, as shown in FIG. 5, after the heat treatment and the development after the exposure are completed again, the wafer 1 is sent to the next exposure step through the steps of etching, cleaning or film formation. To go.

The most significant feature of this embodiment is that in the first exposure step using X-rays and the second exposure step using ultraviolet rays, the scanning directions of exposure are substantially parallel to each other. .

As shown in FIG. 6A, when exposure is performed using a step-and-scan type exposure apparatus, the exposure transfer position becomes ideal due to the inherent error of the stage and the fluctuation of the stage. It often shifts from the position. The area 13a to be exposed and transferred at the same time has a strip shape, and the direction orthogonal to the longitudinal direction is the scanning direction 14. As shown in FIG. 6A, the region 13a is misaligned with respect to the longitudinal direction of the strip-shaped region 13a.
5 is distorted.

When exposure transfer to another layer is performed in the second exposure step on the base formed with a shift in the first exposure step as described above, if the shift in the base is ignored, Although the registration error increases, if the displacement of the base can be detected and the subsequent exposure transfer can be performed in accordance with the detection, the increase in the registration error can be suppressed.

FIG. 7 is a plan view showing the present embodiment and a conventional exposure method. FIG. 7A shows a conventional exposure method, and FIG.
(B) is a plan view showing the exposure method of the present embodiment. As shown in FIG. 7A, in the case of the ordinary step-and-repeat method, in the second exposure step, only a very small number of alignment marks 18a in the exposure area are used to perform exposure transfer to another layer. In such a case, even if the alignment between the alignment marks 18a is perfect, the exposure area becomes distorted like 16 or 17, and an overlay error occurs. .

On the other hand, as in the exposure method of the present embodiment shown in FIG. 7B, the alignment mark 18b of the base pattern formed in the first exposure step is detected.
If the second exposure step is performed while correcting the exposure transfer position based on the detection result, it is possible to prevent an increase in overlay error.

That is, as shown in FIG. 7 (b), the area to be exposed and transferred simultaneously in the second exposure step is
As b, scanning is performed in the direction 20 orthogonal to the longitudinal direction of the strip-shaped region 13b. Further, the scan direction 20 in the second exposure step is set to a direction parallel to the scan direction 14 in the first exposure step. In such a configuration, the position of the base pattern is detected by the alignment mark 18b, and the scan speed or the stage position is finely adjusted based on the detected signal, so that the strip-shaped exposure region 1 is obtained.
The position and the like of 3b on the substrate 11 to be exposed
Transfer 9 By this second exposure step, an area almost the same as the exposure area 15 in the first exposure step can be exposed and transferred, and an overlay error can be prevented.

More specifically, the substrate 1 to be exposed
By scanning the first stage, a mark position on the substrate 11 to be exposed is detected and stored, and during actual exposure, a position is adjusted based on the stored mark position, The method of always detecting the mark position and the focus of the area to be exposed immediately afterward, performing the exposure while giving feedback, detecting the mark position on the substrate 11 to be exposed for each chip 12, and performing fine adjustment of the alignment for each chip Exposure method can be applied.

Furthermore, in order to achieve higher overlay accuracy, it is desirable to have a magnification correction function. Usually, between the first exposure step and the second exposure step, the substrate to be exposed goes through various steps such as etching and film formation. However, through these steps, the substrate to be exposed is caused by film stress. Subject to some expansion and contraction. The degree of expansion and contraction is on the order of ppm. For example, in the case of a chip of about 40 mm, expansion and contraction of about 1 ppm
In some cases, a chip size error of about m may be caused, and may not be ignored for high-accuracy alignment.

Normally, in a step-and-scan type exposure apparatus, in the direction perpendicular to the scanning direction, the magnification is corrected by finely adjusting the reduction ratio of the optical system, and in the direction parallel to the scanning direction. The magnification can be corrected by finely adjusting the scanning speed of the mask or the substrate stage to be exposed.

However, when the substrate to be exposed expands and contracts, there are non-uniform components in the surface due to non-uniformity of the process and unevenness of the flatness of the stage surface on which the substrate to be exposed is mounted. There is. In order to cope with such non-uniform component correction, it is desirable that the magnification correction is not a method of performing uniform correction over the entire surface of the substrate to be exposed, but a method of performing fine adjustment during exposure.

That is, in addition to the second embodiment, the second
In the exposure step, the mark formed in the first exposure step is detected, and based on the detected signal, the mark is scanned in a direction parallel to the scan direction in the first exposure step. By performing the exposure while controlling the magnification, the stage position, and the stage position, it is possible to perform high-accuracy alignment.

The present invention can be effectively applied to the case where the second exposure step using X-rays is performed after the first exposure step using ultraviolet rays, contrary to the previous embodiment. It is.

Further, the present invention is not limited to the combination of the ultraviolet exposure apparatus and the X-ray exposure apparatus as the combination of the exposure apparatuses, but may be used between the ultraviolet exposure apparatuses having different wavelengths or between these exposure apparatuses and the electron beam batch transfer exposure apparatus. It is possible to use a combination between various exposure apparatuses using the step-and-scan method, such as a combination.

(Third Embodiment) FIG. 8 is a flowchart showing the steps of a third embodiment of the present invention. FIG. 9 is a plan view showing a shift in exposure on the substrate to be exposed. FIG.
9B is a plan view showing a substrate to be exposed (wafer), and FIG.
(A) is a plan view showing a shift of exposure in one chip.

As shown in FIG. 8, first, a resist is applied to the exposed substrate (wafer) 21 shown in FIG. 9 and a heat treatment is performed before the exposure. Next, a first exposure process in the first scan direction 24 is performed using a first step-and-scan exposure apparatus using ultraviolet light as a light source. As the first step-and-scan type exposure apparatus, the same one as in the first embodiment is used. The area 23 to be exposed and transferred at the same time has a strip shape, and the direction orthogonal to the longitudinal direction is the scanning direction 24. In FIG. 9, reference numeral 22 denotes a chip, which indicates an exposure unit.

After performing the first exposure step described above, FIG.
As shown in (2), heat treatment and development after exposure are completed, and thereafter, the wafer 21 undergoes processes such as etching, cleaning, and film formation.

Next, as shown in FIG. 8, the displacement of the background caused in the first exposure step is detected. For example, the alignment mark on the base formed by the first exposure process is
Before performing the exposure step. Next, based on the detected signal, the scan direction 24 in the first exposure step
And the displacement in the direction orthogonal to the displacement and the displacement in the parallel direction are compared.

This comparison can be performed, for example, as follows. That is, as realized in the measurement of distortion with respect to the reference grid using a coordinate measuring device or an overlay accuracy measuring device, the deviation from the reference coordinates is quantified, and the numerical value is compared with the scanning direction in the first exposure step. This can be done by comparing the components in the orthogonal direction and the components in the parallel direction.

Next, as shown in FIG. 8, after the application of the resist and the heat treatment before the exposure are performed again, a second step-and-scan type exposure apparatus using X-rays as a light source is used. An exposure step is performed. This first step and
The scanning exposure apparatus shown in FIG. 12 is used as in the first embodiment.

Here, what is important in the present embodiment is the pattern position information comparing means 124 connected to the alignment control system 121, the wafer stage rotation controlling means 125 connected to the comparing means 124, and the rotation control. A wafer stage rotation drive system 126 connected to the means 125 and the wafer stage 115.

The pattern position information of the X-ray mask 112 and the pattern position information of the substrate to be exposed 114 are transmitted from the alignment control system 121 to the pattern position information comparing means 124, and the comparing means 124 compares the above-mentioned shift. Will be The information of the comparison result is transmitted to the wafer stage rotation control means 125, and the rotation drive system 126 drives the wafer stage 115 to rotate around its central axis to set the scan direction on the wafer. I have.

In the second exposure step, the second exposure is performed while scanning is performed in the direction orthogonal to the direction of the larger shift among the shifts in the orthogonal direction and the shift in the parallel direction described above. As shown in FIG. 9A, in this case, the region 25 exposed in the first exposure process is distorted with respect to the ideal exposure region 26, and the scan direction in the first exposure process is The shift in the direction parallel to 24 is larger than the shift in the direction perpendicular to the direction. Therefore, the second exposure step is performed while scanning in the direction orthogonal to the scan direction 24 in the first exposure step. This second exposure step corresponds to the right path in the flowchart of FIG.

The operation of the step-and-scan type exposure apparatus 100 shown in FIG. 12 will now be described. The substrate 21 (114 in FIG. 12) is a wafer stage 115
Placed on An alignment mark provided on the exposed substrate 21 is detected by the alignment optical system 120, and based on a signal detected by the optical system 120, a shift and a parallel shift in a direction orthogonal to the scan direction at the time of the first exposure are performed. Are compared by the pattern position information comparing means 124. On the basis of the comparison result by the comparison means 124, the wafer stage rotation control means 125 and the wafer stage rotation control means 125 perform scanning in the direction orthogonal to the direction of the large deviation of the two directions to perform the second exposure. Wafer stage 1 using stage rotation drive system 126
The direction of the substrate 21 to be exposed is controlled by adjusting the rotation of 15.

Next, as shown in FIG. 8, after the heat treatment and the development after the exposure are completed again, the wafer 21 is sent to the next exposure step through the steps of etching, cleaning, or film formation. To go.

The most significant feature of this embodiment is that the displacement of the background caused in the first exposure step is detected, and the displacement in the direction orthogonal to the scan direction in the first exposure step and the parallel displacement are detected based on the detected signal. The second exposure is performed by comparing the deviations in different directions and performing scanning in a direction orthogonal to the direction of the larger deviation in the two directions.

As described above, when a step-and-scan type exposure apparatus is used, the exposure in the first exposure step is caused by the inherent error of the stage, the fluctuation of the stage, the distortion inherent to the optical system, and the like. The transfer position often deviates from the ideal position. As described above, the direction of the displacement of the base that occurs in the first exposure process is determined by the steps used.
It varies depending on the type of the AND-scan type exposure apparatus, and in reality, it cannot be unconditionally determined.

For example, as described above, in the first embodiment, a shift occurs in a direction parallel to the scan direction in the first exposure step, and in the second embodiment, a shift occurs in a direction orthogonal to the scan direction. . Also, as in the present embodiment, the first
In the exposure step, a shift in a direction parallel to the scan direction and a shift in a direction orthogonal to the scan direction are both generated, and the shift as a whole may be the sum of these shifts.

According to the present embodiment, the displacement of the background caused in the first exposure step is detected in advance before the second exposure step is performed, and the scan in the second exposure step is performed based on the detected signal. It is determined whether to perform the scanning in the direction parallel to or perpendicular to the scanning direction of the first exposure process. Therefore, regardless of whether the deviation in the direction perpendicular to the scan direction in the first exposure step is large or the deviation in the parallel direction is large, the second exposure step is performed with smooth and accurate alignment in any case. It has been found that it is possible to obtain good results. In this case, in order to realize high-precision distortion correction, it is desirable to correct a large distortion component by optical correction in the longitudinal direction of the exposure area and correct a small component by fine adjustment of the stage movement. Can be

Contrary to the above-described embodiment, the shift in the direction perpendicular to the scan direction 24 in the first exposure step may be larger than the shift in the parallel direction. In this case, the following operation is performed. Do. FIG. 10 is a plan view showing the exposure shift on the substrate to be exposed in that case. FIG.
FIG. 10B is a plan view showing a substrate (wafer) to be exposed, and FIG.
(A) is a plan view showing a shift of exposure in one chip.

As shown in FIG. 10A, an area 35 to be exposed in the first exposure step is distorted with respect to an ideal exposure area. The shift in the orthogonal direction is larger than the shift in the parallel direction. In the second exposure step, the second exposure is performed while performing scanning in the direction orthogonal to the direction of the larger deviation among the deviation in the orthogonal direction and the deviation in the parallel direction. As a result, the scan in the first exposure step is performed. The second exposure process is performed while scanning in a direction parallel to the direction 34. This second exposure step corresponds to the left path in the flowchart of FIG. Even in this case, the second exposure step can be performed with smooth and high-accuracy alignment. In FIG. 10, 31
Is a substrate to be exposed (wafer), 32 is a chip (exposure unit),
An area 33 is simultaneously exposed and transferred.

More specifically, the substrate 2 to be exposed
By scanning the stages 1 and 31, mark positions on the exposed substrates 21 and 31 are detected and stored, and at the time of actual exposure, alignment is performed based on the stored mark positions. A method of always detecting the mark position and the focus of the area to be exposed immediately after the exposure, and performing the exposure while giving feedback; detecting the mark positions on the exposed substrates 21 and 31 for each of the chips 22 and 32; For example, a method of exposing while performing fine adjustment of the alignment can be applied.

Further, similarly to the first and second embodiments,
In order to achieve higher overlay accuracy, it is desirable to have a magnification correction function. That is, in a normal step-and-scan type exposure apparatus, in the direction perpendicular to the scanning direction, the magnification is corrected by finely adjusting the reduction ratio of the optical system, and in the direction parallel to the scanning direction, The magnification can be corrected by finely adjusting the scanning speed of the mask or the substrate stage to be exposed.

Here, in the expansion and contraction of the substrate to be exposed, there are non-uniform components in the surface due to the non-uniformity of the process and the unevenness of the flatness of the stage surface on which the substrate to be exposed is mounted. There are cases. In order to cope with such non-uniform component correction, it is desirable that the magnification correction is not a method of performing uniform correction over the entire surface of the substrate to be exposed, but a method of performing fine adjustment during exposure.

Therefore, in conjunction with the previous embodiment, at the time of the second exposure step, the mark formed by the first exposure step is detected, and based on the detected signal, the mark of the first exposure step is detected. By performing exposure while controlling the scanning speed, magnification, and stage position while scanning in a direction orthogonal to or parallel to the scanning direction at the time, highly accurate positioning can be performed.

Also, as described in the first embodiment, contrary to the previous embodiment, when the second exposure step using ultraviolet rays is performed after the first exposure step using X-rays, Also, the present invention can be effectively applied.

Further, the present invention is not limited to the combination of the ultraviolet exposure apparatus and the X-ray exposure apparatus, as in the first and second embodiments, but may be the combination between various exposure apparatuses using the step-and-scan method. Can be used.

(Fourth Embodiment) FIG. 11 shows a fourth embodiment of the present invention.
FIG. 9 is a plan view showing a shift of a pattern on a substrate to be exposed in the embodiment. FIG. 11B shows a substrate to be exposed (wafer).
FIG. 11A is a plan view showing a pattern shift in one chip.

As shown in FIG. 11, the first exposure step (not limited to the step-and-scan type exposure method,
Other exposure methods may be used. ), A wiring group 44 is formed as a pattern on the chip (exposure unit) 42 of the substrate to be exposed (wafer) 41 in the longitudinal direction of the chip 42. The wiring group 44 is formed to extend in the lateral direction 46 of the chip 42. An interlayer insulating film (not shown) is formed on the wiring group 44.

In the present embodiment, the wiring group 44
For each of these, a contact hole 45 for electrically connecting the wiring group 44 and an upper wiring formed in a later step is formed at any part of the interlayer insulating film. In order to form a resist pattern for opening the contact hole 45, as shown in FIG. 12, a second step-and-scan exposure apparatus using X-rays as a light source is used to apply and expose a resist. Exposure is performed on the exposed substrate 41 that has been subjected to the previous heat treatment.

Here, the step-and-
The scanning X-ray exposure apparatus differs from that of the third embodiment in that a pattern position information determining means 127 is provided instead of the pattern position information comparing means 124.

The pattern position information of the X-ray mask 112 and the pattern position information of the substrate to be exposed 114 are transmitted from the alignment control system 121 to the pattern position information determining means 127. A large direction is determined, and information of the determination result is transmitted to the wafer stage rotation control means 125. The rotation drive system 126 drives the wafer stage 115 to rotate around its central axis, thereby setting the scan direction on the wafer. Is being done.

The most significant feature of this embodiment is that a part of the pattern (the wiring group 44 and the other conductive layers) formed by the first exposure is detected, and the pattern is shifted based on the detected signal. Determines the largest direction,
The second exposure is performed using an AND-scan type exposure apparatus while performing scanning in a direction orthogonal to the direction in which the displacement is greatest.

That is, as a part of the pattern, for example, a part of the wiring group 44 or an alignment mark provided separately from the wiring group is used, the position is detected, and the position of the wiring group 44 is determined based on the detected signal. The direction in which the deviation is the largest is determined.

This determination can be made, for example, as follows. That is, as is realized in the measurement of distortion with respect to the reference grid using a coordinate measuring device or an overlay accuracy measuring device, the deviation from the reference coordinates is quantified, and the direction in which the numerical value becomes maximum is determined. It is possible.

In the present embodiment, the substrate 4 to be exposed is subjected to various steps such as etching of a wiring film and formation of an interlayer insulating film between the first exposure step and the second exposure step.
The one wiring group 44 undergoes some expansion and contraction due to the film stress. The wiring group 44 is particularly susceptible to expansion and contraction in the longitudinal direction 46, so that the position of the contact hole 45 to be opened in the longitudinal direction 46 is greatly shifted. Since it is necessary to perform the second exposure step in accordance with this positional deviation, the second exposure may be performed while scanning in a direction 47 orthogonal to the direction of the deviation (longitudinal direction 46). . In this case, the region to be exposed and transferred at the same time is a strip-shaped region 43 parallel to the wiring group 44, and scanning is performed in a direction 47 orthogonal to the longitudinal direction 46 of this region 43.

Here, the operation of the step-and-scan type exposure apparatus 100 shown in FIG. 12 will be described. Similarly to the third embodiment, the substrate 41 to be exposed (11 in FIG. 12)
4) is mounted on the wafer stage 115. The alignment mark provided on the substrate 41 to be exposed is detected by the alignment optical system 120, and based on the signal detected by the optical system 120, the direction in which the pattern (wiring group 44) has the largest displacement (wiring group 44). Is determined by the pattern position information determining means 127. This determination means 1
Based on the determination result by the wafer 27, the wafer is rotated by using the wafer stage rotation control means 125 and the wafer stage rotation drive system 126 so that the exposure can be performed by scanning in the direction 47 orthogonal to the direction of the determined shift. The direction of the substrate 41 is controlled by adjusting the rotation of the stage 115.

Next, after the heat treatment and the development after the exposure are completed again, the wafer 41 is sent to the next exposure step through processes such as etching and cleaning for forming the contact hole 45.

According to the present embodiment, even when the underlying pattern is deviated from the ideal position, for example, when the wiring group 44 expands and contracts in the longitudinal direction 46 and the position of the contact hole 45 is largely deviated, It is possible to perform the second exposure step with smooth and highly accurate alignment,
It has been found that good results are obtained. In this case, in order to realize high-precision distortion correction, it is desirable to correct a large distortion component by optical correction in the longitudinal direction of the exposure area and correct a small component by fine adjustment of the stage movement. Can be

More specifically, the substrate 4 to be exposed
By scanning the first stage, the mark position on the substrate 41 to be exposed is detected and stored, and during actual exposure, a position is adjusted based on the stored mark position, The method of always detecting the mark position and the focus of the area to be exposed immediately afterward, performing the exposure while applying feedback, detecting the mark position on the substrate 41 to be exposed for each chip 42, and finely adjusting the alignment for each chip Exposure method can be applied.

The present invention is not limited to the above embodiment. For example, it is also possible to scan in a direction perpendicular to the direction in which the deviation of the positional deviation is large, instead of in the direction perpendicular to the direction in which the absolute value of the positional deviation is large.

That is, in the fine adjustment of the stage movement, generally, the adjustment of the high frequency component is apt to cause the deterioration of the accuracy because the stage moves at a high speed. Easy. For this reason, scanning is performed in a direction orthogonal to the direction in which the required variation in correction is large, and correction in the direction having large variation, that is, high frequency component, is performed by optical correction. Is desirably corrected by fine adjustment of the stage movement. In addition, various modifications can be made without departing from the spirit of the invention.

[0100]

As described above, according to the exposure method and exposure apparatus of the present invention, when performing step-and-scan exposure, it is possible to perform high-accuracy superposition on a base pattern. Become.

[Brief description of the drawings]

FIG. 1 is a flowchart showing steps according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a shift in exposure on a substrate to be exposed according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram illustrating a shift in exposure on a substrate to be exposed according to the first embodiment of the present invention.

FIG. 4 is a plan view showing an exposure method according to the first embodiment of the present invention.

FIG. 5 is a flowchart showing steps according to a second embodiment of the present invention.

FIG. 6 is a plan view showing exposure deviation on a substrate to be exposed according to a second embodiment of the present invention.

FIG. 7 is a plan view showing an exposure method according to the first embodiment of the present invention and a conventional exposure method.

FIG. 8 is a flowchart showing steps according to a third embodiment of the present invention.

FIG. 9 is a plan view showing exposure shift on a substrate to be exposed according to a third embodiment of the present invention.

FIG. 10 is a plan view showing an example of another shift of exposure on a substrate to be exposed according to a third embodiment of the present invention.

FIG. 11 is a plan view showing a pattern shift on a substrate to be exposed according to a fourth embodiment of the present invention.

FIG. 12 is a schematic view showing the structure of a step-and-scan type exposure apparatus according to the present invention.

[Explanation of symbols]

1, 11, 21, 31, 41: substrate to be exposed (wafer) 2, 12, 22, 32, 42: exposure unit (chip) 3a, 3b, 13a, 13b, 23, 33, 43: exposure to be exposed simultaneously Areas 4, 10, 14, 20, 24, 34, 44, 47 ... Scanning directions 5, 15, 16, 17, 25, 35 ... Transfer pattern shapes to be actually exposed (distortion is emphasized) 26: ideal transfer pattern shape 7, 46: strip longitudinal direction (scan orthogonal direction) 8, 18a, 18b: alignment mark 9, 19: pattern shape transferred by the second exposure when correction is performed 44: wiring group 45: contact hole

Claims (18)

[Claims] A step of performing a first exposure using a step-and-scan type exposure apparatus; and a step of performing a first exposure using a step-and-scan type exposure apparatus. Performing a second exposure while scanning in a direction orthogonal to the first direction. 2. The method according to claim 1, wherein a part of the pattern formed by the first exposure is detected, and the second exposure is performed while absorbing a shift of the first exposure based on a detected signal. The exposure method according to claim 1, wherein 3. A part of the pattern formed by the first exposure is detected, and the second exposure is performed while controlling at least one of a scan speed, a magnification, and a stage position based on the detected signal. 3. The exposure method according to claim 1, wherein the exposure is performed. 4. The first exposure and the second exposure,
4. The exposure method according to claim 1, wherein the exposure is performed using a mix-and-match method. 5. A step of performing a first exposure using a step-and-scan type exposure apparatus, and a step of performing a first exposure using a step-and-scan type exposure apparatus. Performing a second exposure while scanning in a parallel direction. 6. The method according to claim 1, wherein a part of the pattern formed by the first exposure is detected, and the second exposure is performed while absorbing a shift of the first exposure based on a detected signal. The exposure method according to claim 5, wherein 7. A part of the pattern formed by the first exposure is detected, and the second exposure is performed while controlling at least one of a scan speed, a magnification, and a stage position based on the detected signal. 7. The exposure method according to claim 5, wherein the exposure is performed. 8. The first exposure and the second exposure,
8. The exposure method according to claim 5, wherein the exposure is performed using a mix-and-match method. 9. A step of performing a first exposure using a step-and-scan type exposure apparatus, a step of detecting a part of a pattern formed by the first exposure, and Comparing the deviation in the direction orthogonal to the scanning direction and the deviation in the parallel direction based on the first exposure based on the first exposure, and using a step-and-scan type exposure apparatus, Performing a second exposure while scanning in a direction orthogonal to the direction of the shift. 10. The method according to claim 1, wherein a part of the pattern formed by the first exposure is detected, and the second exposure is performed while absorbing a shift of the first exposure based on a detected signal. The exposure method according to claim 9, wherein 11. A part of the pattern formed by the first exposure is detected, and the second exposure is performed while controlling at least one of a scan speed, a magnification, and a stage position based on the detected signal. 10. The method according to claim 9, wherein
Or the exposure method according to 10. 12. The exposure method according to claim 9, wherein the first exposure and the second exposure are exposures using a mix-and-match method. 13. A step of performing a first exposure to form a pattern, a step of detecting a part of the formed pattern, and a step of detecting a direction in which the pattern is largest based on a detected signal. The decision process and the step-and-
Performing a second exposure while scanning in a direction orthogonal to the direction of the largest deviation using a scanning type exposure apparatus. 14. The exposure according to claim 13, wherein a part of the formed pattern is detected, and the second exposure is performed while absorbing a shift of the pattern based on a detected signal. Method. 15. The method according to claim 15, wherein a part of the formed pattern is detected, and the second exposure is performed while controlling at least one of a scan speed, a magnification, and a stage position based on the detected signal. The exposure method according to claim 13, wherein the exposure method is performed. 16. The exposure method according to claim 13, wherein the first exposure and the second exposure are exposures using a mix-and-match method. 17. A step-and-scan type exposure apparatus comprising: a rotatable sample stage on which a sample to be exposed is mounted; and an exposure optical system for controlling exposure of the sample to be exposed. Detecting means for detecting a part of a pattern on the sample to be exposed formed by one exposure, and a direction orthogonal to a scanning direction at the time of the first exposure based on a signal detected by the detecting means. Comparing means for comparing the displacement and the displacement in the parallel direction, and performing the second exposure by performing scanning in a direction orthogonal to the direction of the larger displacement among the displacements in the two directions based on a comparison result of the displacement by the comparing means. Control means for adjusting the rotation of the sample stage to control the direction of the sample to be exposed on which the first exposure has been performed. 18. A step-and-scan type exposure apparatus comprising: a rotatable sample stage on which a pattern-formed sample to be exposed is mounted; and an exposure optical system for controlling exposure of the sample to be exposed. Detecting means for detecting a part of the pattern on the sample to be exposed; determining means for determining a direction in which the pattern displacement is greatest based on a signal detected by the detecting means; The rotation of the sample stage is adjusted to control the orientation of the sample to be exposed so that the scanning can be performed in a direction orthogonal to the direction in which the deviation is the largest and the exposure can be performed based on the determination result by the means. An exposure apparatus, comprising: