JP2001215316A - Method of producing diffraction optical device and method for exposure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the position with high accuracy even on a substrate coated with a photoresist. SOLUTION: The method includes a step of irradiating the rugged pattern on a sample 106 coated with a photoresist with a tracking beam so as to detect the relative position of a converged beam 105 and the sample 106 when the sample 106 is exposed to the converged beam 106 for exposure. The tracking beam is made incident on the sample 106 so as to satisfy the relation of cosθ=λ/4nd, wherein d is the height of the rugged pattern, λ is the wavelength of the tracking beam, n is the refractive index of the photoresist at wavelength λand θ is the incident angle of the tracking beam on the rugged pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a diffractive optical element and an exposure method for exposing a ring pattern, and further relates to a method for manufacturing the same and a diffractive optical element manufactured using the exposure method. The present invention relates to an optical system, an optical device, and an exposure apparatus.

[0002]

2. Description of the Related Art In recent years, a diffractive optical element has been attracting attention as an optical element. In this method, when an annular pattern is formed on a glass substrate and irradiated with light, the light is diffracted at an angle corresponding to the period of the annular ring and plays a role like a lens.

FIG. 8 shows an example of a diffractive optical element. FIG.
(A) is a diffractive optical element called a Fresnel zone plate, in which a metal film such as chromium is deposited on a glass substrate,
By drawing a Fresnel zone by a lithography process or the like, a light-shielding portion where a metal film or the like remains and a light-transmitting portion without a film are formed. FIG. 8B is a cross-sectional view of a Fresnel lens in which one period of the periodic structure in the radial direction of the annular zone forms a continuous curved surface, and is formed by cutting or pressing. FIG. 8C shows a diffractive optical element called a binary optics element, which is obtained by processing the surface of a glass substrate into a stepped cross-sectional structure by a plurality of lithography processes.

A conventional rotary exposure apparatus for manufacturing a diffractive optical element having an annular pattern as shown in FIG. 8 is shown in FIG.
Shown in

In FIG. 9, reference numeral 901 denotes a light source for exposure;
02 is an illumination optical system, 903 is a shutter system, 904 is a converging optical system, 905 is a converging beam, 906 is a sample which is a glass substrate, 907 is a rotary stage, and 908 is a concentric annular pattern. . 901 to 9
Reference numeral 04 denotes an exposure optical system 909. An electromagnetic wave (e.g., ultraviolet light) from the light source 901 is shaped into a beam suitable for exposure by the illumination optical system 902, and is converged to a desired beam spot size on the sample 906 through the converging optical system 904. By rotating the stage 907, an annular pattern is exposed on the sample. Further, the stage 907 or the optical system 909 relatively moves in the radial direction of the sample, so that concentric circular patterns having different radii are exposed.

[0006]

Conventionally, when manufacturing a diffractive optical element as shown in FIG. 8 (c), first, a first layer is coated with a resist, patterned by exposure, and etched to form irregularities on the substrate surface. A step structure is sequentially formed on the element surface by applying the second layer again by resist application, pattern exposure, and etching. When the exposure is performed by overlapping the third and fourth layers to process a further multi-step structure, a series of processes similar to the above are repeated. At this time, the problem is the overlay accuracy with the already processed lower layer.

In the case of exposure using a rotary exposure apparatus as shown in FIG. 9, if the center of the concentric circular pattern of the first layer and the rotation center of the stage when exposing the second layer do not coincide, the two layers are shifted laterally. Is manufactured. When superposing more layers, the centers of all the patterns need to coincide with the rotation center of the stage.
A manufacturing error due to the misalignment causes a decrease in diffraction efficiency, which is one index of the optical performance of the diffractive optical element.

As a conventional technique for solving this problem, there is provided a method of manufacturing a diffractive optical element which detects a position of a pattern formed before the overlay exposure and performs alignment based on the detected position information. The method is disclosed in JP-A-8-15
No. 509.

In the method disclosed in Japanese Patent Application Laid-Open No. 8-15509, the edge of the pattern area on the substrate surface is detected through the applied photoresist, but the refractive index of the glass substrate of the diffractive optical element is Since the refractive index of the photoresist is close to the refractive index of the photoresist and the reflectance at the interface is extremely small, the signal contrast for detecting the edge portion is low, which is insufficient for securing high position detection accuracy.

The present invention has been made in view of the above prior art, and has as its object to provide a method capable of performing position detection with high accuracy even on a substrate coated with a photoresist as a photosensitive material. I do.

[0011]

According to a first aspect of the present invention, when a substrate coated with a photoresist is exposed to a first electromagnetic wave beam, second irregularities on the substrate are exposed. Irradiating an electromagnetic wave beam to detect a relative position between the first electromagnetic wave beam and the substrate, wherein the height of the irregularities is d, the wavelength of the second electromagnetic wave beam is λ,
Assuming that the refractive index of the photoresist at the wavelength λ is n and the incident angle θ of the second electromagnetic wave beam to the substrate, the second electromagnetic wave beam is incident on the substrate so as to satisfy cos θ = λ / 4nd. It is characterized by having

It is preferable that the method of manufacturing a diffractive optical element according to the first aspect of the present invention includes a step of changing the relative position of the substrate based on the detected information on the relative position of the substrate with respect to the first electromagnetic wave beam.

[0013] The second invention of the present application is an exposure step in which a substrate coated with a photoresist is placed on a rotary stage, and the rotary stage is rotated with respect to a first electromagnetic wave beam to expose the substrate to an annular pattern. A method of irradiating a second electromagnetic wave beam to a boundary between an exposed portion of the photoresist exposed by the first electromagnetic wave beam and a non-exposed portion of the photoresist, the first electromagnetic wave beam and the substrate. It is characterized by detecting a relative position.

In the exposure method according to the second aspect of the present invention, it is preferable that the relative position is changed based on the detected relative position information of the substrate with respect to the first electromagnetic wave beam.

Further, the third invention of the present application is an exposure apparatus used for exposing the substrate in the method of manufacturing a diffractive optical element of the first invention of the present application, wherein the means for supplying the first electromagnetic wave beam; It is characterized by having means for holding a substrate and means for detecting the relative position of the substrate.

According to a fourth aspect of the present invention, there is provided an exposure apparatus used for exposing the substrate in the exposure method of the second aspect of the present invention, wherein the means for supplying the first electromagnetic wave beam, the rotating stage, Means for detecting the relative position of the substrate.

The diffractive optical element of the fifth invention of the present application is
Exposure of the substrate coated with photoresist using the exposure method of the invention, a series of processes for forming the substrate surface unevenness using a pattern obtained by developing the photoresist is repeated a plurality of times It is characterized by being manufactured by forming a staircase structure thereon.

An optical system according to a sixth aspect of the present invention is characterized in that it has a diffractive optical element manufactured by the method for manufacturing a diffractive optical element according to the first aspect of the present invention or the diffractive optical element according to the fifth aspect of the present invention.

An optical apparatus according to a seventh aspect of the present invention includes the optical system according to the sixth aspect of the present invention.

An exposure apparatus according to an eighth aspect of the present invention includes the optical system according to the sixth aspect of the present invention.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Various embodiments according to the present invention will be described below.

(Embodiment 1) FIG. 1 is a schematic configuration diagram of a rotary exposure apparatus for explaining a first embodiment. This embodiment is an embodiment in which a concentric step pattern (annular pattern) already processed on a sample in a previous process is used as a guide for tracking.

In FIG. 1, reference numeral 101 denotes a light source for supplying an exposure light beam (first electromagnetic wave beam), 102 denotes an illumination optical system,
103 is a shutter system, 104 is a converging optical system, 105 is a converging beam, 106 is a sample, 107 is a rotating stage, 1
Reference numeral 08 denotes an annular pattern that has already been processed on the sample 106 in the previous step. Reference numeral 109 denotes a light source for supplying a tracking light beam (second electromagnetic wave beam); 110, an irradiation optical system; 111 and 112, mirrors; 115, incident light;
16 is an outgoing light, 113 is a light receiving optical system, 114 is a detection system,
117 is a processing system. Reference numerals 101 to 104 and an exposure optical system 118 are provided, and reference numerals 109 to 114 are fixedly provided in the exposure optical system 118 as tracking systems.

An exposure light beam from a light source 101 shaped into a beam suitable for exposure by an illumination optical system 102 is converged to a desired beam spot size on a sample 106 via a shutter system 103 and a converging optical system 104. In exposing the annular pattern, a sample (glass substrate or the like) 106 coated with a photoresist is rotated by a rotating stage 107 to irradiate the sample 106 with an exposure light beam. Then, the rotary stage 107 or the exposure optical system 118 is relatively moved in the radial direction 119 of the sample 106 to expose concentric patterns having different radii. In this embodiment, the exposure optical system 118 is fixed, and has an X stage (not shown) for moving the rotary stage 107 in the direction 119 with respect to the exposure optical system 118.

In this embodiment, a series of processes such as resist coating, exposure, development, and processing (etching or deposition) are repeated a plurality of times to form a step structure on the sample 106, as shown in FIG. He produces a diffractive optical element called a binary optics element. Here, the exposure step in the above series of processes will be described.

First, in the step of exposing the first layer, the sample 1
While rotating the rotary stage 107 on which 06 is mounted, the rotary stage 107 is step-moved in the direction of 119. Convergent beam 105
Is located at a radial position where exposure is not required, the shutter 103 is closed and the resist applied to the sample 106 is not exposed. The sample 106 is moved by the step movement.
Has reached the radial position of the ring pattern to be exposed,
The shutter 103 is opened, and the convergent beam 105 exposes the radial position with the width of the convergent spot. Since the stage 107 is rotating, the exposed pattern has an annular shape.
When the convergent beam 105 continues to the center of rotation of the rotary stage 107, the exposure of the first layer is completed.

Next, the exposure process for the second and subsequent layers will be described. Second
In the exposure step after the layer, the sample 106 is once removed from the rotating stage 107, and a step of concentric pattern unevenness is formed through processing such as development and etching by another process device. In addition, since the sample 106 is once removed from the rotary stage 107 and mounted on the rotary stage again, the center of the annular pattern does not always coincide with the rotation center of the rotary stage 107.

FIG. 2 is an enlarged view of the sample 106. FIG.
2A is a top view, and FIG. 2B is a cross-sectional view taken along a line AA '. In FIG. 2A, 201 is a convergent beam to be exposed, 202 is a tracking beam, 203 is a ring already exposed in the current process, 204 is a ring currently being exposed,
Reference numeral 205 denotes a lower annular pattern. In FIG. 2B, reference numeral 206 denotes a profile of a lower annular pattern,
Reference numeral 208 denotes an exposed resist, and reference numeral 209 denotes an area irradiated with a tracking beam. Since the tracking system is fixed to the exposure optical system 118, the positional relationship between the spots 201 and 202 is always constant.

At the time of exposure of the second layer, if the center of the lower annular pattern 205 coincides with the rotation center of the rotary stage 107, the step of the lower annular pattern 205 is shifted in the radial direction (arrow r in FIG. 2). Direction). However, if the rotation centers do not match, the step will vibrate in the direction of r according to the rotation cycle.

The tracking beam supplied from the light source 109 shown in FIG. 1 is shaped by the irradiation optical system 110 and is made incident on the edge of the uneven step of the lower annular pattern 205 as shown by 209. The light reflected and scattered by the step is passed through the light receiving optical system 113, and is transmitted to the CCD.
And the like. The intensity distribution of light detected by the detection system 114 changes when the ring pattern 205 moves in the radial direction, and becomes constant when the ring pattern 205 does not move. However, as described above, since the refractive index of the glass substrate as the sample 106 is close to the refractive index of the unexposed resist and the reflectance at the interface is extremely small, the signal contrast for detecting the edge of the step becomes low, It is difficult to ensure high position detection accuracy. Therefore, in this embodiment,
When the height of the step of the unevenness is d, the wavelength of the tracking beam is λ, the refractive index of the resist at the wavelength λ is n, and the incident angle θ with respect to the step of the tracking beam, cos θ = λ / 4nd (1) is satisfied. A tracking beam is incident on the sample 106.

When the tracking beam is incident on the sample 106 so as to satisfy this condition, the center of the reflected light becomes dark under the interference condition. Therefore, it is necessary to detect the movement of the depression of the intensity distribution of the intensity distribution monitored by the detection system 114. Therefore, it is possible to easily detect that the step in the lower layer moves in the radial direction, and high position detection accuracy can be secured. Now, when the height d of the step is 250 nm, the wavelength λ of the tracking beam is 1.3 μm, and the refractive index n of the resist at the wavelength λ is 1.45, the incident angle with respect to the resist is set to about 40 ° by the above interference condition. Then, the incident angle θ with respect to the step in the resist is about 30 °, and the center of the reflected light becomes dark, so that position detection with high accuracy becomes possible.

FIG. 3 shows an example of the intensity distribution detected by the detection system 114. FIG. 3B shows the intensity distribution when there is a step in the lower layer at the center of the tracking beam, FIG. 3A shows the intensity distribution when the step is shifted to the left, and FIG. 3C shows the intensity distribution when the step is shifted to the right. ing. If the exposure light beam is ultraviolet light and the resist has a property of being sensitive to electromagnetic waves in the ultraviolet region, infrared light (wavelength 1.3 μm) is used as the tracking beam.
By using m) and making the wavelength different from the wavelength of the exposure light beam, tracking (position detection) can be performed without exposing the resist. Alternatively, the resist can be prevented from being exposed to the tracking beam even if a tracking beam having a weak intensity that does not have the sensitivity of the resist is used.

When the detection system 114 detects that the unevenness of the step moves to the left or right, the processing system 117 sends a signal to an X stage (not shown) and performs feedback so as to keep the position of the lower annular pattern constant. I do. In this way, the sample 106 is reciprocated on the X stage while being rotated on the rotary stage 107, so that even if the center of the lower annular pattern does not coincide with the rotation center of the rotary stage 107, the center of the layer currently being exposed and the lower layer are exposed. Are performed so that the centers of the circles coincide with each other.

The tracking beam spot 20
Since the desired positional relationship between 2 and the spot 201 of the convergence beam for exposure changes depending on the radius of the ring during exposure, the position of the tracking beam is mirrored from the design data of the ring pattern and the current exposure radius. 111, 112
, Or offset the data of the intensity distribution of the detection system to correct the feedback signal.
In addition, since the sensitivity of tracking detection varies depending on the height of the step in the lower layer, the refractive index of the resist, and other process factors, the wavelength, polarization, incident angle, and the like of the tracking beam are optimized depending on the process and the sample.

According to the present embodiment, since a rotary exposure apparatus having high overlay exposure accuracy can be provided, a diffraction optical element having high diffraction efficiency and little unnecessary light can be manufactured.

(Embodiment 2) FIG. 4 is an enlarged view of a sample (substrate) for explaining the first embodiment. The configuration of the rotary exposure apparatus is the same as that of the first embodiment shown in FIG.

The present embodiment is an embodiment in which tracking is performed by irradiating a tracking beam on a boundary between a photosensitive portion and a non-exposed portion of a resist that has been exposed and deteriorated by an exposure light beam. This embodiment is particularly suitable for the first
This is effective when exposing a concentric pattern of the layer. FIG.
, 401 is a converging spot of an exposure light beam, 402 is a spot of a tracking beam, 403 is an annular pattern currently being exposed, and 404 is an exposed annular pattern.

As in the first embodiment, the tracking beam is applied to the sample 106 through the irradiation system 110. In this embodiment, the tracking beam is applied to the exposed ring pattern 404 other than the currently exposed ring pattern 401. The exposed portion of the resist (photosensitive portion) has a change in refractive index, surface shape, etc., compared to the non-photosensitive portion (non-photosensitive portion) due to a chemical reaction. By irradiating the tracking beam to the portion, the intensity distribution of the reflected light indicates the position of this boundary portion. By processing the signal output from the detection system 114 and feeding it back to the X stage so as to keep this intensity distribution constant, even if the rotation stage 107 is deviated from the axis, a concentric circle with a desired radial position is drawn. It becomes possible to do.

Also in the present embodiment, the relative position between the spot 402 of the tracking beam and the spot 401 of the convergence beam for exposure changes in a desired positional relationship depending on the radius of the ring during exposure. The position of the tracking beam is controlled by the mirrors 111 and 112 based on the data and the current exposure radius, or the detection system 114
The data of the intensity distribution is offset and the feedback signal is corrected. Also, the refractive index of the resist,
Since the tracking detection sensitivity fluctuates due to other process factors, the wavelength, polarization, incident angle, and the like of the tracking beam are optimized depending on the process and the sample.

According to the present embodiment, it is possible to provide a rotary exposure apparatus having high positioning accuracy, and to manufacture a diffractive optical element having high diffraction efficiency and little unnecessary light.

(Embodiment 3) FIG. 5 is a schematic configuration diagram of a rotary exposure apparatus for explaining a third embodiment. The present embodiment is an embodiment in which a tracking beam irradiates a guide on a sample other than a pattern or a deteriorated portion. In particular, in the present embodiment, the periphery of the sample is used as this guide.

In FIG. 5, reference numeral 501 denotes a light source for supplying an exposure light beam, 502 denotes an illumination optical system, 503 denotes a shutter system,
Reference numeral 504 denotes a converging optical system, 505 denotes a converging beam, 506 denotes a sample, 507 denotes a rotating stage, and 508 denotes an annular pattern. Reference numeral 509 denotes a light source for supplying a light beam for tracking; 510, an irradiation optical system; 511, a half mirror;
5 is an incident light and an outgoing light, 513 is a light receiving optical system, 514 is a detection system, and 517 is a processing system. Reference numerals 501 to 504 denote an exposure optical system 518, and reference numerals 509 to 514 denote a tracking system 521, which are driven along a guide 520 by a drive unit (not shown).

The exposure light beam from the light source 501 shaped into a beam suitable for exposure by the illumination optical system 502 is converged to a desired beam spot size on the sample 506 via a shutter system 503 and a converging optical system 504. When exposing the ring pattern, the sample 506 coated with the photoresist is rotated by a rotating stage 507 to irradiate the sample 506 with an exposure light beam. Then, the rotary stage 507 or the exposure optical system 518 is relatively moved in the radial direction 519 of the sample 506, thereby exposing concentric patterns having different radii. In this embodiment, the exposure optical system 518 is fixed, and the rotation stage 507 is mounted on the exposure optical system 518.
, Which is moved in the direction of 519 with respect to.

In this embodiment, as in the first embodiment, a series of processes of resist coating, exposure, development, and processing (etching or deposition) is repeated a plurality of times to form a step structure on the sample 506, and FIG. A diffractive optical element called a binary optics element as shown in FIG. Here, the exposure step in the above series of processes will be described.

First, in the exposure step of the first layer, the sample 5
While rotating the rotary stage 507 on which 06 is mounted, the rotary stage 507 is step-moved in the direction of 519. Convergent beam 505
Is located at a radial position that does not require exposure, the shutter 503 is closed and the resist applied to the sample 506 is not exposed. The sample 506 is moved by the step movement.
Has reached the radial position of the ring pattern to be exposed,
The shutter 503 is opened, and the convergent beam 505 exposes its radial position with the width of the convergent spot. Since the stage 507 is rotating, the exposed pattern has an annular shape.
When this is continued and the convergent beam 505 advances to the rotation center of the rotary stage 507, the exposure of the first layer is completed.

In the step of exposing the first layer, the tracking system 521 adjusts the sample 506 so as to satisfy the above equation (1).
The outer periphery (outer edge) of the light source is irradiated with light, and the position is detected by the reflected and scattered light.
By driving the X stage based on the position information detected in step 1, the desired relationship between the outer periphery of the sample 506 and the exposure convergent beam is maintained. Then, rotate the stage 507 to X
When the tracking system 521 is moved by the stage, the tracking system 521 is also moved along the guide 520 with a movement amount substantially equal to the movement amount of the rotating stage 507, so that the tracking beam is always irradiated near the outer periphery of the sample 506, It is possible to monitor the reflected light. The tracking system 521 is fixed at the position of the guide 519 so that the distance between the outer circumference of the sample 506 and the desired ring becomes constant during the exposure of the ring having the desired radius, and the outer circumference is positioned with respect to the tracking beam spot. By feeding back to the X stage so as not to fluctuate, the ring whose position with respect to the outer periphery is compensated is exposed.

Next, the exposure process for the second and subsequent layers will be described. Second
In the exposure step after the layer, the sample 506 is once removed from the rotary stage 507, and a step of concentric pattern unevenness is formed through processing such as development and etching by another process device. In addition, since the sample 506 is once removed from the rotary stage 507 and mounted on the rotary stage again, the center of the annular pattern does not always coincide with the rotation center of the rotary stage 507. But,
Since the pattern of the first layer is exposed and processed concentrically with the outer periphery, by exposing with the same exposure method and tracking method as the first layer, the circular pattern of the second layer and thereafter is also concentric with the outer periphery of the sample 506. As a result, concentric circles are exposed with the annular pattern of the first layer.

The tracking beam uses the outer corners and side walls of the sample 506 as a tracking guide,
The same effect can be obtained by using an annular groove for tracking provided near the outer periphery of the sample 506.

According to the present embodiment, it is possible to provide a rotary exposure apparatus with high positioning accuracy, and to manufacture a diffractive optical element with high diffraction efficiency and little unnecessary light.

(Embodiment 4) In the fourth embodiment, tracking is performed while modulating a tracking beam. “Modulation” in the present embodiment refers to deflecting a beam.

The configuration of the rotary exposure apparatus of this embodiment is shown in FIG.
Is substantially the same as the first embodiment shown in FIG.
Reference numeral 10 includes an acousto-optic modulation element so that the spot of the tracking beam reciprocates slightly in the radial direction of the sample. A sawtooth wave is input to the acousto-optic modulator, and the forward path is moved slowly with respect to the backward path. When the beam moves in the radial direction, a change appears in the reflected light or the scattered light when passing through the step in the lower layer or the boundary of the resist altered portion (photosensitive portion) exposed on the previous circumference. The change in the reflected light is detected, and the phase of the signal is compared with the waveform input to the acousto-optic modulator. If the phase does not change, a certain interval is maintained at the step between the convergent beam and the lower layer used as a reference, or at the boundary between the affected portions of the resist exposed on the previous circumference.
The information based on this phase is processed and fed back to the X stage to correct the position of the rotating stage 107. The same effect can be obtained by providing the illumination optical system of the second or third embodiment with a similar effect.

In this modulation method, a piezo element or the like is used in addition to the acousto-optic modulation element, and the mirror 11 shown in FIG.
A similar effect can be obtained by vibrating 1.

(Fifth Embodiment) In the fifth embodiment, tracking is performed while modulating the tracking beam, as in the fourth embodiment.
Refers to changing the light intensity of the beam.

The configuration of the rotary exposure apparatus of this embodiment is also the same as that of FIG.
However, the tracking light source 109 in FIG. 1 is a light source that can change the amount of light (light intensity) by changing a current or a voltage, and uses, for example, a semiconductor laser or the like. . In the present embodiment, the amount of the tracking beam is modulated at a constant frequency when the relative position is detected by irradiating the step on the pattern already processed in the previous process with the tracking beam. Detection system 114
After the reflected light is detected by the processing unit 117, unnecessary electric noise is removed by extracting only the signal of this frequency by the electric filter in the processing system 117, and a tracking signal with a high S / N ratio can be obtained. . A similar intensity-modulated light source can be obtained by using a two-wavelength light source having a slightly different frequency in addition to changing the current and voltage of the light source. The same effect can be obtained by providing the tracking light source of the second or third embodiment with a similar effect.

(Embodiment 6) The sixth embodiment uses a plurality of convergent beams for pattern exposure. In the rotary exposure apparatus of the first embodiment, by providing a plurality of exposure optical systems 118, it is possible to improve the exposure throughput. The plurality of optical systems converge at different convergent spot diameters, so that a beam with a large spot diameter shares an inner pattern with a small radius and a beam with a small spot diameter shares an outer pattern with a large radius. By arranging the sample at slightly different radial positions and at different angular positions of the sample, the effect of improving the throughput can be obtained.

(Embodiment 7) In the seventh embodiment, a plurality of tracking beams are provided for one pattern exposure beam. In the rotary exposure apparatus of the first embodiment, a plurality of sets of the tracking systems 109 to 114 may be arranged. FIG. 6 is an enlarged view around the convergent spot of the sample when a plurality of tracking beams are used. Reference numeral 601 denotes a converging spot of an exposure light beam, 602a and b denote tracking beam spots, 603 denotes an annular pattern currently being exposed, 604 denotes an exposed annular pattern, and 605 denotes a pattern step already processed in the previous process. .

The spot 602a irradiates the pattern step 605 already processed in the previous step, and the detection system detects the reflected light or the scattered light. On the other hand, spot 602
b irradiates a beam on the boundary between the photosensitive portion and the non-photosensitive portion of the already exposed annular pattern, and the detection system detects the reflected light or the scattered light. The signal detection is the same as in the first and second embodiments. The position information obtained by these two signals is processed by the processing system and fed back to the X stage, so that the position of the convergence beam for exposure can be accurately adjusted to a desired position with respect to the lower layer pattern and the outer annular pattern. Can be controlled. To share the processing system, 2
Position detection can also be performed by irradiating both of the two tracking beams to the step of the processed pattern or by irradiating the boundary between the photosensitive portion and the non-photosensitive portion of the exposed circular pattern.

Further, in order to simplify the optical system, the beam is split into a plurality of beams by a beam splitter from one tracking beam light source, and the number of spots is set at a position on the light source side almost conjugate with the sample surface by the tracking irradiation optical system. It is also possible to obtain a plurality of spots by arranging a mask provided with holes according to the above, illuminating the mask and forming an image with an irradiation optical system.

In the first to seventh embodiments described above, the deviation between the rotation axis and the center of the sample is corrected by applying feedback to an X stage (not shown). This is an example of a method of applying feedback. If the X stage cannot be finely moved, only the coarse movement is performed on the X stage. The minute relative position correction by feedback is performed by fine movement on the side of the exposure optical system or reflection in the exposure optical system. The relative position may be finely adjusted by fine adjustment of an optical system such as a mirror.

(Embodiment 8) Next, an embodiment of a semiconductor exposure apparatus using a diffractive optical element manufactured by the method described in Embodiments 1 to 7 as a projection optical system will be described.

FIG. 7 shows semiconductor devices such as ICs and LSIs,
FIG. 3 is a schematic diagram of a main part of an exposure apparatus used in an exposure process when manufacturing an imaging device such as a CCD and a device such as a magnetic head. 7, reference numeral 71 denotes a light source, 72 denotes a pattern-formed reticle, 73 denotes a reticle stage, 74 denotes a lens barrel, 75 denotes a diffractive optical element, 76a to 76c denote ordinary refractive lenses, 77 denotes a wafer, and 78 denotes a wafer stage. It is. The projection optical system 79 of the exposure apparatus according to the present embodiment includes a combination of a diffractive optical element 75 and refraction lenses 76a to 76c.

In the exposure apparatus of the present embodiment, in the exposure step, the wafer 77 coated with the resist by the wafer stage 78 is positioned at a desired position, and the height of the wafer 77 is adjusted to a focus position by a focus detection means (not shown). Adjust to Then, a shutter (not shown) is opened, the reticle 72 is illuminated by the illumination light from the light source 71, and the pattern on the reticle 72 is projected and exposed on the wafer 77 by the projection optical system 79. Also, lenses 76a to 76c
At least one of them is capable of moving up and down slightly to cope with expansion and contraction of the wafer 77 due to thermal distortion and the like.
The magnification correction and the aberration correction of the projection optical system 79 can be performed.

In this embodiment, since the diffractive optical element 75 is used for the projection optical system 79, it is possible to realize a projection optical system having high optical performance while reducing the thickness of the optical member.
For example, even when an ultraviolet light source such as an ArF excimer laser is used as an exposure light source, a projection optical system with high transmittance and less deterioration can be realized.

Further, since the diffractive optical element 75 having high diffraction efficiency and less adverse effects such as unnecessary diffracted light is used for the projection optical system 79, a semiconductor exposure apparatus suitable for semiconductor exposure requiring high resolution can be provided.

The diffractive optical element manufactured by the method described in each of the first to seventh embodiments can be widely applied not only to the exposure apparatus described in the present embodiment but also to general-purpose optical equipment.

[0066]

As described above, according to the method and the method for manufacturing a diffractive optical element of the present invention, position detection can be performed with high accuracy even on a substrate coated with a photoresist.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a rotary exposure apparatus for explaining a first embodiment.

FIG. 2 is an enlarged view of a main part of the sample according to the first embodiment.

FIG. 3 is a diagram illustrating an intensity distribution detected by the detection system according to the first embodiment.

FIG. 4 is an enlarged view of a main part of a sample according to a second embodiment.

FIG. 5 is a schematic configuration diagram of a rotary exposure apparatus for explaining a third embodiment.

FIG. 6 is an enlarged view of a main part of a sample according to a seventh embodiment.

FIG. 7 is a schematic configuration diagram of an exposure apparatus of an eleventh embodiment.

FIG. 8 is an explanatory diagram of a diffractive optical element.

FIG. 9 is a schematic configuration diagram of a conventional rotary exposure apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Light source for exposure 102 Illumination optical system 103 Shutter system 104 Convergent optical system 105 Convergent beam 106 Sample 107 Rotating stage 108 Concentric pattern 109 Tracking light source 110 Irradiation optical system 111 Mirror 112 Mirror 113 Light receiving optical system 114 Detection system 115 Incident light 116 Outgoing light 117 Processing system 118 Exposure optical system

Claims (18)

[Claims] A first substrate coated with a photoresist;
When exposing with an electromagnetic wave beam, the method includes irradiating a second electromagnetic wave beam to the unevenness on the substrate to detect a relative position between the first electromagnetic wave beam and the substrate. d, the wavelength of the second electromagnetic wave beam is λ, the refractive index of the photoresist at the wavelength λ is n,
Wherein the second electromagnetic wave beam is incident on the substrate so that cos θ = λ / 4nd is satisfied when the incident angle θ of the electromagnetic wave beam with respect to the unevenness is set. 2. The method of manufacturing a diffractive optical element according to claim 1, further comprising the step of changing the relative position of the first electromagnetic wave beam based on the detected information on the relative position between the first electromagnetic wave beam and the substrate. Method. 3. The method according to claim 1, further comprising the step of irradiating the second electromagnetic wave beam while modulating it.
A method for manufacturing the diffractive optical element according to the above. 4. The method of manufacturing a diffractive optical element according to claim 1, wherein said first electromagnetic wave beam and said second electromagnetic wave beam are electromagnetic waves having different wavelengths. 5. The method for manufacturing a diffractive optical element according to claim 1, wherein the second electromagnetic wave beam is an electromagnetic wave having an intensity not exposing the photoresist. 6. An exposure method for arranging a substrate coated with a photoresist on a rotary stage and exposing the substrate to an annular pattern by rotating the rotary stage with respect to a first electromagnetic wave beam. A second electromagnetic wave beam is applied to a boundary portion between a photosensitive portion exposed by the first electromagnetic wave beam and a non-exposed portion of the photoresist to detect a relative position between the first electromagnetic wave beam and the substrate. An exposure method, comprising: 7. The exposure method according to claim 6, wherein the relative position is changed based on information on the detected relative position between the first electromagnetic wave beam and the substrate. 8. The exposure method according to claim 6, wherein the irradiation is performed while modulating the second electromagnetic wave beam. 9. The exposure method according to claim 6, wherein said first electromagnetic wave beam and said second electromagnetic wave beam are electromagnetic waves having different wavelengths. 10. The exposure method according to claim 6, wherein the second electromagnetic wave beam is an electromagnetic wave having an intensity that does not expose the photoresist. 11. The exposure method according to claim 6, wherein the substrate is exposed with a plurality of the first electromagnetic wave beams. 12. The exposure method according to claim 6, wherein a plurality of the second electromagnetic wave beams are irradiated to detect a relative position between the first electromagnetic wave beam and the substrate. . 13. An exposure apparatus used for exposing the substrate in the method of manufacturing a diffractive optical element according to claim 1, wherein: a means for supplying the first electromagnetic wave beam; An exposure apparatus comprising: means for holding the substrate; and means for detecting a relative position of the substrate. 14. An exposure apparatus used for exposing said substrate in the exposure method according to claim 6, wherein said means for supplying said first electromagnetic wave beam; Means for detecting a relative position of the substrate. 15. A substrate coated with a photoresist is exposed by using the exposure method according to claim 6, and the surface of the substrate is formed to have irregularities using a pattern obtained by developing the photoresist. A diffractive optical element manufactured by forming a staircase structure on a substrate by repeating a series of processes described above a plurality of times. 16. An optical system comprising the diffractive optical element manufactured by the method for manufacturing a diffractive optical element according to claim 1 or the diffractive optical element according to claim 15. 17. An optical apparatus comprising the optical system according to claim 16. 18. An exposure apparatus comprising the optical system according to claim 16.