JP2003100612A - Surface position detecting apparatus, method of adjusting the focusing apparatus, surface position detecting method, exposing apparatus and method of manufacturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface position detecting apparatus and method capable of accurately detecting the surface position to be detected, a method of adjusting the focusing apparatus which enables accurate calibration manipulation, an exposing apparatus which can improve the exposing accuracy and a method of effectively manufacturing device of the high integration density. SOLUTION: The detecting surface 76 of a wave-front aberration measuring unit 75 is set to the focusing surface of a projected optical system PL using an AF sensor 45 based on the reference position previously stored in a control system 33. A measuring beam RL including an image of pin-hole PH of a test reticle Rt is controlled to be incident to the wave-front aberration measuring unit 75 to measure the wave- front aberration information of the projected optical system PL and this measuring beam RL is developed to various elements including the defocus element using the polynomial of Zernike. Location of the detecting surface 76 is adjusted to make zero the defocus element and the location of the detecting surface 76 is measured again with the AF sensor 45. The AF sensor 45 can be calibrated by updating the location information of the detecting surface 76 with the re-measurement of the reference location.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface position detecting device and a surface position detecting method for detecting the position of a surface to be inspected with respect to an image forming surface of an optical system. The present invention also relates to a method for adjusting a focusing device that aligns a surface to be inspected with a focusing position of an optical system such as an autofocus device. Further, the present invention is, for example, a semiconductor device,
An exposure apparatus used in a photolithography process in the manufacturing process of devices such as liquid crystal display elements, image pickup elements, thin film magnetic heads, high frequency filters, and laser diodes,
It also relates to a method of manufacturing the device.

[0002]

2. Description of the Related Art A focusing device using a surface position detecting device of this type, which is used as, for example, an exposure device for manufacturing a semiconductor element, is a so-called oblique incidence type autofocus device (hereinafter referred to as "AF device"). ".) Is known. This AF apparatus includes a projection unit that projects an image of a pattern illuminated by a predetermined light from a diagonal direction on the surface of a wafer that is a surface to be inspected, and a light receiving unit that receives reflected light of the image of the pattern on the wafer surface. Is equipped with. Then, the position of the wafer surface is detected by comparing the detection position of the reflected light of the image of the pattern in the light receiving unit with a preset reference position.

Here, in the AF device, it is necessary to set the reference position to the detection position of the reflected light in a state where the wafer surface is arranged at the position of the image plane of the projection optical system. Such a reference position setting operation is generally called focus calibration (hereinafter referred to as “calibration operation”).

For example, the following is known as this calibration operation. That is, openings having a predetermined pattern are provided on the wafer stage that holds the wafer. This opening is arranged in a plane including the wafer surface in the optical axis direction of the projection optical system. The opening is illuminated from the inside of the wafer stage with predetermined light (light having the same wavelength as the exposure light, or exposure light), and the calibration light that has passed through the opening is made incident on the projection optical system. The calibration light that has passed through the projection optical system is reflected by the surface of the reticle arranged on the object plane of the projection optical system. The light reflected by this reticle is incident on the projection optical system again, and an image of the aperture is projected on the aperture on the wafer stage. Then, at least a part of the light reflected by the reticle enters the wafer stage through the opening, and is received by the light receiving element arranged in the wafer stage so as to face the opening.

Here, the image of the aperture projected on the wafer stage is closest to the size of the aperture when the aperture is at the image plane of the projection optical system, and the illuminance is large. Become. On the other hand, as the aperture moves away from the position of the image plane of the projection optical system, the projected image of the aperture becomes blurry and its illuminance also decreases. Therefore, the wafer stage is moved in the optical axis direction of the projection optical system, and the position of the image plane of the projection optical system is detected from the position where the amount of light received by the light receiving element is maximum. And
In this state, the detection position of the reflected light in the light receiving unit of the AF device is set to the reference position.

[0006]

However, in the above-mentioned conventional configuration, the calibration light reciprocates in the projection optical system during the calibration operation of the AF device. This calibration light is greatly affected by various aberrations remaining in the projection optical system. The image of the aperture projected on the wafer stage after being reflected by the reticle may be deformed or misaligned due to the aberrations. For this reason, there is a problem in that the amount of reflected light received by the reticle that passes through the opening of the light receiving element is reduced, and the accuracy of detecting the position of the image plane in the projection optical system may be reduced.

In particular, in recent years, the degree of integration of semiconductor elements has remarkably increased, and the miniaturization of patterns has been remarkable. Along with this, the demand for higher resolution of the exposure apparatus is remarkably increasing. In order to meet such an increasing demand, in exposure apparatuses, the wavelength of exposure light is being shortened and the numerical aperture of the projection optical system is being expanded. Here, when increasing the numerical aperture of the projection optical system, there is a problem that the depth of focus becomes shallow. As described above, in the exposure apparatus, it becomes necessary to strictly align the surface of the wafer with the position of the image plane of the projection optical system prior to the exposure. For this purpose, it is necessary to improve the accuracy of alignment with the position of the image plane in the AF device, and it is necessary to perform the calibration operation of the AF device with higher accuracy.

The present invention has been made by paying attention to the problems existing in such conventional techniques. An object of the present invention is to provide a surface position detecting device and a surface position detecting method capable of detecting the position of a surface to be inspected more accurately, and an adjusting method of a focusing device capable of more accurate calibration operation. . Another object of the present invention is to provide an exposure apparatus capable of improving exposure accuracy and capable of exposure to a finer pattern, and a device manufacturing method capable of manufacturing a highly integrated device with high yield.

[0009]

In order to achieve the above object, the invention according to claim 1 of the present application provides a surface position detection equipped with a detection mechanism for detecting the position of the surface to be inspected with respect to the image plane of the optical system. In the apparatus, a wavefront aberration measuring mechanism that obtains wavefront aberration information of the optical system, and corrects position information of the surface to be detected detected by the detecting mechanism based on the wavefront aberration information obtained by the wavefront aberration measuring mechanism. And a correction device.

According to the first aspect of the present invention, when detecting the position of the surface to be inspected with respect to the image plane of the optical system, the position information of the surface to be inspected is corrected based on the wavefront aberration information of the optical system. To be done. Therefore, the influence of various aberrations remaining in the optical system is eliminated from the position information of the surface to be inspected, and the position information of the surface to be inspected with respect to the image plane of the optical system can be detected more accurately.

The invention according to claim 2 is the invention according to claim 1, wherein the image forming surface of the optical system is based on position information of the surface to be detected detected by the detecting mechanism. And an adjusting mechanism for adjusting the relative position of the surface to be inspected,
A control mechanism for controlling the wavefront aberration measuring mechanism, and for obtaining the wavefront aberration information of the optical system after the relative position is adjusted by the adjusting mechanism.

According to the invention described in claim 2, in addition to the operation of the invention described in claim 1, based on the position information of the surface to be detected with respect to the image plane of the optical system detected by the detection mechanism. The relative position between the image plane and the surface to be inspected is adjusted. In this state, since the wavefront aberration information of the optical system is obtained, it is possible to more accurately grasp the influence of the wavefront aberration information of the optical system on the position information of the surface to be inspected.

The invention according to claim 3 of the present application is the invention according to claim 1 or 2, wherein the correction mechanism uses the defocus component of the wavefront aberration information to perform the detection. The position information of the surface to be detected detected by the mechanism is corrected.

According to the invention of claim 3 of the present application, in addition to the function of the invention of claim 1 or 2,
The defocus component of the wavefront aberration information changes according to the position of the surface to be inspected with respect to the image plane of the optical system. Therefore, it is possible to easily and more accurately grasp the separated state of the surface to be inspected from the image plane.

The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the wavefront aberration measuring mechanism has a surface to be inspected. It is characterized in that it is mounted in a fixed or detachable manner with respect to a member-to-be-tested member holding mechanism for holding a member.

In the invention according to claim 4 of the present application, in addition to the operation of the invention according to any one of claims 1 to 3, position information of the surface to be detected detected by the detection mechanism is provided. Can be easily and accurately corrected as required. In particular, when the wavefront aberration measuring mechanism is detachably mounted on the member-to-be-inspected holding mechanism, the wavefront aberration measuring mechanism can be removed when it is unnecessary, and the entire apparatus including the optical system can be downsized. Become.

The invention according to claim 5 of the present application is the invention according to any one of claims 1 to 4, wherein the wavefront aberration measuring mechanism is within the image plane of the optical system. The wavefront aberration information of the optical system is obtained at a plurality of measurement positions, and the correction device corrects the position information of the test surface based on the obtained plurality of wavefront aberration information. .

According to the invention described in claim 5, in addition to the operation of the invention described in any one of claims 1 to 4, for example, a field curvature or an image plane curvature is formed on an image forming surface of an optical system. In the case where the image plane tilt occurs, it becomes possible to distribute the depth of focus of the optical system at each measurement position based on the wavefront aberration information at the plurality of measurement positions.

In the invention according to claim 6 of the present application, in the invention according to claim 5, the detection mechanism detects the position of the surface to be detected within the image plane of the optical system. A plurality of detection positions are set, and at least one measurement position of the plurality of measurement positions coincides with at least one of the plurality of detection positions.

According to the sixth aspect of the present invention, in addition to the operation of the fifth aspect of the invention, the wavefront aberration information of the optical system is obtained at the detection position for detecting the position of the surface to be inspected. Therefore, it becomes possible to more accurately correct the position information of the surface to be detected at the detection position.

The invention according to claim 7 of the present application is based on a detection mechanism for detecting the position of the surface to be inspected with respect to the image plane of the optical system, and position information of the surface to be inspected detected by the detection mechanism. Then, in the adjusting method of the focusing device including the adjusting mechanism for adjusting the relative position between the image plane of the optical system and the surface to be inspected, the wavefront aberration information of the optical system is obtained, and the obtained wavefront aberration information is obtained. The relative position between the image plane of the optical system and the surface to be inspected in the adjusting mechanism is corrected based on the above.

In the invention according to claim 7 of the present application, the relative position between the image plane of the optical system and the surface to be inspected is corrected based on the wavefront aberration information of the optical system, so that the relative position is unexpected. It is possible to accurately eliminate the deviation that has occurred.

The invention according to claim 8 is a surface position detecting method for detecting a position of a surface to be inspected with respect to an image forming surface of an optical system, based on wavefront aberration information of the optical system,
It is characterized in that the position information of the detected surface to be detected is corrected.

In the invention described in claim 8 of the present application, almost the same operation as that of the invention described in claim 1 is achieved. The invention according to claim 9 of the present application is an exposure apparatus for transferring a pattern on a mask onto a substrate via a projection optical system, wherein the surface according to any one of claims 1 to 6 is used. It is characterized by including a position detecting device, and the surface position detecting device detects a position of a surface of the substrate with respect to an image forming surface of the projection optical system.

According to the ninth aspect of the present invention, the position of the substrate surface can be detected more accurately, and the alignment of the substrate surface with the image plane of the projection optical system or the alignment position in the vicinity thereof can be performed. The accuracy of operation is improved.

According to a tenth aspect of the present invention, in a device manufacturing method including a lithography step, exposure is performed in the lithography step by using the exposure apparatus according to the ninth aspect. is there.

According to the tenth aspect of the present invention, the exposure accuracy is improved, and it becomes possible to manufacture a highly integrated device with a high yield. Next, technical ideas further included in the invention described in each of the claims will be described below together with their actions.

(1) The detection mechanism receives a light projecting system for irradiating the surface to be inspected with predetermined light obliquely and a light reflected from the surface to be inspected from the light projecting system. 7. The surface position detecting device according to claim 6, further comprising a light receiving system, wherein the plurality of detection positions are set by the light projecting system and the light receiving system.

Therefore, according to the configuration described in (1), a predetermined pattern is inserted in the light projecting system, an image of the pattern is projected on the surface to be inspected, and the image of the pattern is used. By receiving the reflected light on the surface to be inspected by the light receiving system, it is possible to easily set a plurality of detection positions.

(2) The surface position detecting device according to any one of claims 1 to 6, wherein the wavefront aberration measuring mechanism comprises a Shack-Hartmann system wavefront aberration measuring device.

Therefore, according to the structure described in (2), the wavefront aberration information of the optical system can be detected by the wavefront aberration measuring device having a simple structure.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) A first embodiment of the present invention will be described below with reference to FIGS.

First, the schematic structure of the exposure apparatus will be described. As shown in FIG. 1, the exposure light source 21 emits pulsed light such as KrF excimer laser light, ArF excimer laser light, and F2 laser light as the exposure light EL. The exposure light EL serves as an optical integrator, for example, a fly-eye lens 2 including a large number of lens elements.
Incident on 2. A large number of secondary light source images corresponding to the respective lens elements are formed on the emission surface of the fly-eye lens 22. A rod lens may be used as the optical integrator. The exposure light EL emitted from the fly-eye lens 22 is relay lenses 23a and 23b, a reticle blind 24, and a mirror 2.
5. A circuit pattern of a semiconductor element or the like is drawn through the condenser lens 26, and is incident on the reticle R as a mask placed on the reticle stage RST.

Here, the composite system of the fly-eye lens 22, the relay lenses 23a and 23b, the mirror 25, and the condenser lens 26 superimposes the secondary light source image on the reticle R, and illuminates the reticle R with uniform illuminance. The illumination optical system 27 is configured. The reticle blind 24 is
The light shielding surface is arranged so as to have a conjugate relationship with the pattern area of the reticle R. That reticle blind 2
Reference numeral 4 is composed of a plurality of movable light-shielding plates (for example, two L-shaped movable light-shielding plates) that can be opened and closed by the reticle blind drive unit 28. By adjusting the size (slit width or the like) of the opening formed by these movable light-shielding plates, the illumination area for illuminating the reticle R is arbitrarily set.

The reticle stage RST can be moved in a predetermined direction (scanning direction (Y direction)) by a reticle stage drive unit 29 composed of a linear motor or the like. In addition, in FIG. 1, a projection optical system PL described later is used.
The direction along the optical axis AX is the Z direction, the direction orthogonal to the optical axis of the projection optical system PL and the paper surface is the X direction, and the direction orthogonal to the optical axis of the projection optical system PL and the paper surface is the Y direction. Further, the reticle stage RST is capable of finely moving in a plane perpendicular to the optical axis AX of the exposure light EL in the X direction perpendicular to the scanning direction and being capable of fine rotation about the optical axis AX. keeping.

At the end of the reticle stage RST,
A movable mirror 31 that reflects the laser beam from the interferometer 30 is fixed. The interferometer 30 constantly detects the position of the reticle stage RST in the scanning direction, and the position information is sent to the reticle stage controller 32. The reticle stage control unit 32 controls the operation of the entire exposure apparatus, and controls the reticle stage drive unit 29 based on the position information of the reticle stage RST under the control of the main control system 33 that constitutes the correction mechanism and the control mechanism. The reticle stage RST is controlled and moved.

The exposure light EL that has passed through the reticle R is
For example, the light enters the projection optical system PL that is telecentric on both sides. The projection optical system PL reduces the projected image obtained by reducing the circuit pattern on the reticle R to, for example, 1/5 or 1/4,
A substrate W whose surface is coated with a photoresist having photosensitivity to the exposure light EL and a wafer W as a test member
It is formed on the exposed surface Wf which is the surface to be inspected.

The wafer W is held on the wafer stage WST via a Z stage 36 and a wafer holder 37 which constitute an adjusting mechanism and a member holding mechanism to be inspected. Z
The stage 36 is a Z stage drive unit 3 including a motor and the like.
8, the optical axis of the projection optical system PL can be tilted in any direction with respect to the optimum image plane of the projection optical system PL, and the optical axis AX direction (Z
Direction). Further, wafer stage WST is not only moved in the scanning direction (Y direction) by wafer stage drive unit 39 such as a motor, but also a plurality of shot areas SAij (FIG. 3) divided on exposure surface Wf of wafer W. It is also configured to be movable in a direction (X direction) perpendicular to the scanning direction so that it can be moved arbitrarily with respect to the reference (see). As a result, each shot area SAij on the wafer W is
A step-and-scan operation in which scanning exposure is repeated every time is possible.

A movable mirror 41 that reflects the laser beam from the interferometer 40 is fixed to the end of the wafer stage WST, and the interferometer 40 constantly detects the position of the wafer stage WST in the X and Y directions. To be done. The position information (or speed information) of wafer stage WST detected by interferometer 40 is sent to wafer stage controller 42. Then, under the control of the main control system 33, the wafer stage controller 42 controls the wafer stage driver 39 based on the position information (or speed information) of the wafer stage WST.

Here, when the circuit pattern on the reticle R is scanned and exposed on the shot area SAij on the wafer W by the step-and-scan method, the illumination area on the reticle R is a rectangle (slit) on the reticle blind 24. Shaped into a shape. This illumination area has a longitudinal direction in a direction orthogonal to the scanning direction (+ Y direction) on the reticle R side. Then, by scanning the reticle R at a predetermined speed Vr during exposure, the circuit pattern on the reticle R is sequentially illuminated from one end side to the other end side in the slit-shaped illumination region. This allows
The image of the circuit pattern on the reticle R in the illumination area is exposed through the projection optical system PL to the exposure surface W of the wafer W.
The projection area is formed by projecting on f.

Since the wafer W has an inverted image forming relationship with the reticle R, the wafer W is moved in a direction opposite to the scanning direction of the reticle R (-Y direction) in synchronization with the scanning of the reticle R at a predetermined speed. Scan at Vw. As a result, the entire surface of the shot area SAij of the wafer W can be exposed. The scanning speed ratio Vw / Vr accurately corresponds to the reduction magnification of the projection optical system PL, and the image of the circuit pattern on the reticle R is accurately reduced and transferred onto each shot area SAij on the wafer W. It

Above the wafer stage WST, a focus position detection system (hereinafter, AF position detection system as a detection mechanism for detecting the position in the Z direction of the exposure surface Wf which is the surface to be inspected of the wafer W held by the wafer holder 37. 45),
The projection optical system PL is arranged so as to sandwich it from the left and right.
The AF sensor 45 employs a so-called grazing incidence optical system, and a projection system 45a for irradiating the exposure surface Wf of the wafer W with predetermined illumination light obliquely from above and an exposure of the wafer W with a projection image based on the illumination. The light receiving system 45b receives the image forming light (reflected light) of the reflected image from the surface Wf. The position information from the AF sensor 45 is sent to the main control system 33, and the main control system 33 sends the Z stage drive unit 3 via the wafer stage control unit 42 based on the position information.
Control eight. As a result, the Z stage 36 is moved in the Z direction, and the exposure surface Wf of the wafer W is arranged at the best focus position which is substantially coincident with the image forming surface of the projection optical system PL.

Next, the configuration of these AF sensors 45 will be described in more detail. As shown in FIG. 2, the projection system 45a of the AF sensor 45 uses, as the predetermined illumination light, illumination light having a wavelength different from that of the exposure light EL and not exposing the photoresist on the wafer W to light. It is guided through an optical fiber bundle 46 from a non-illuminating light source. The illumination light emitted from the optical fiber bundle 46 passes through the condenser lens 47, and is provided with a number of slit-shaped openings SP-ij (i = 1 to 7, j =
1 to 7, see FIG. 6).

The illumination light transmitted through the pattern forming plate 48 is projected onto the exposure surface Wf of the wafer W through the lens 49, the mirror 50 and the irradiation objective lens 51. This allows
In a predetermined shot area SAij of the exposure surface Wf, the image AF- of the slit-shaped opening SP-ij on the pattern forming plate 48 is formed.
ij (i = 1 to 7, j = 1 to 7, see FIG. 5) is 4 in the X direction and the Y direction with respect to the optical axis AX of the projection optical system PL.
The image is projected and imaged obliquely from the direction inclined by 5 °. The illumination light reflected by the exposure surface Wf of the wafer W is generated by the projection optical system PL.
Condensing objective lens 5 of the light receiving system 45b arranged in a direction inclined by 45 ° with respect to the optical axis AX of the X direction and the Y direction.
2. After passing through the rotation direction vibration plate 53 and the imaging lens 54, it is re-projected on the light receiving surface of the light receiving device 55 which constitutes the position detecting mechanism. As a result, the image of the slit-shaped opening SP-ij on the pattern forming plate 48 is re-imaged on the light receiving surface of the light receiver 55.

The rotation direction vibration plate 53 includes a vibration device 56.
And is vibrated as described later under the control of the main control system 33. On the light receiving surface of the light receiver 55, a large number of light receiving sensors SI-ij (i = 1 to 7, j = 1 to 7,
(See FIG. 7) are provided, and those light receiving sensors SI
The detection signal from -ij is supplied to the signal processing device 57.
The signal processing device 57 synchronously detects the detection signal from each of the light receiving sensors SI-ij with the drive signal of the vibration device 56,
A large number of focus signals that form the position information of the exposure surface Wf of the wafer W can be obtained. The signal processing device 57 supplies a large number of focus signals to the main control system 33.

Next, the operation of the AF sensor 45 will be described in detail. FIG. 6 shows the pattern forming plate 48.
FIG. Here, for convenience of explanation, an X′-Y ′ coordinate system inclined by 45 ° is defined as shown in the figure. The pattern forming plate 48 has seven slit-shaped openings SP.
-11 to SP-17 are formed side by side in the X'direction. Further, the pattern forming plate 48 is formed with seven slit-shaped openings SP-11 to SP-71 aligned in the Y ′ direction. That is, a total of 49 slit-shaped openings SP-ij (i = 1 to 7, j = 1 to 7) are formed in the square or rectangular pattern forming plate 48 so as to form a rhombus as a whole. ing.

Then, the slit-shaped openings SP-ij are formed by the illumination light emitted from the optical fiber bundle 46.
As shown in FIG. 5, the pattern image formed by
Is projected obliquely with respect to the X and Y directions on the exposure surface Wf. That is, 1 on the exposure surface Wf of the wafer W
Within the one shot area SAij, the seven detection points AF-11 to AF-17 in the first row and the seven detection points in the second row are arranged in the X direction in order from the top in the Y direction in FIG. AF-21 to AF-27, similarly the detection point AF-31 in the third row
~ AF-37, similarly the detection points AF-41 to AF-4 in the 4th row
7, similarly to the detection points AF-51 to AF-57 of the fifth row, the detection points AF-61 to AF-67 of the sixth row, and the detection points AF-71 to AF-77 of the seventh row, respectively. Each opening S
All 49 images corresponding to P-ij are projected. Here, each of the detection points AF-ij has a predetermined area and can also be referred to as a detection area.

FIG. 7 shows the arrangement of the light receiving sensors SI-ij (i = 1 to 7, j = 1 to 7) on the light receiver 55. Here, for convenience of description, as shown in FIG.
Define a 5'tilt X'-Y 'coordinate system. The light receiver 5
On the 5 side, seven light receiving sensors SI-11 to SI-17 are X '
They are arranged side by side. In addition, the light receiver 5
On the 5, the seven light-receiving sensors SI-11 to SI-71 are Y '.
They are arranged side by side. That is, a total of 49 light receiving sensors SI-ij are arranged in a square or rectangular light receiver 55 so as to form a rhombus as a whole, and a slit shape (not shown) is formed on each light receiving sensor SI-ij. The diaphragm is arranged.

Then, an image of the pattern of the slit-shaped aperture SP-ij projected on each detection point AF-ij in FIG. 5 is re-formed on each of these light receiving sensors SI-ij. For example, the image of the pattern of the slit-shaped opening SP-11 is imaged on the detection point AF-11 on the exposure surface Wf of the wafer W, and is further imaged on the light receiving sensor SI-ij.

Here, the rotation direction vibration plate 53 of FIG.
Is reciprocally oscillated so as to oscillate the position of each image in the lateral direction of the aperture width of the diaphragm when the reflected light from the exposure surface Wf is re-imaged on the light receiver 55. The detection signal detected by each light receiving sensor SI-ij is sent to the signal processing device 57.
Is supplied to. The signal processing device 57 synchronously detects each detection signal with a signal of the rotational vibration frequency,
For each detection point AF-ij on the wafer W, a position signal corresponding to the position of the projection optical system PL in the optical axis direction is generated and supplied to the main control system 33.

Next, the control operation of the Z stage 36 will be described. As shown in FIG. 3, the Z stage 36 is
It is supported on the lower surface member on the lower surface of the Z stage 36 through three supporting mechanisms 60 to 62. Each support mechanism 60
Up to 62 are independently expandable and contractable in the focus direction (direction parallel to the optical axis AX of the projection optical system PL, that is, Z direction). Then, the AF sensor 45
Under the control of the main control system 33, the support mechanism drive unit 63 is controlled on the basis of the position information of the exposure surface Wf of the wafer W based on the information about the reference position of the Z stage 36 stored in the main control system 33 beforehand. ~ 65 through each support mechanism 60 ~ 62
The amount of expansion and contraction is adjusted. Here, the reference position of the Z stage 36 is a position at which the exposure surface Wf of the wafer W placed on the Z stage 36 is arranged at the best focus position of the projection optical system PL. is there.

With this adjustment, the exposure surface Wf of the wafer W is moved to the best focus position of the projection optical system PL by Z.
While the alignment position of the stage 36 is set,
The inclination angles of the Z stage 36 in the X and Y directions are set to desired values. This controls the height and leveling of the Z stage 36. Each support mechanism 60-62
Height sensors 66 to 68 that can detect the amount of displacement of each of the support mechanisms 60 to 62 in the focus direction with a resolution of, for example, about 0.01 μm are attached in the vicinity of.

By the way, when the positions where the support mechanisms 60 to 62 are arranged are fulcrums TL1 to TL3, respectively,
The two fulcrums TL1 and TL2 are arranged on a straight line parallel to the Y axis. Further, the fulcrum TL3 is the two fulcrums T
It is arranged on the perpendicular bisector of the line segment connecting L1 and TL2.

Then, as described above, when the leveling control of the Z stage 36 is completed, that is, when the exposure surface Wf of the wafer W becomes substantially parallel to the image plane of the projection optical system PL, the Z stage 36. Focus control, that is, the aligning operation of the exposure surface Wf of the wafer W with respect to the target reference position is performed. In this case, the alignment of the exposure surface Wf is performed by displacing the three support mechanisms 60 to 62 by the same amount.

Next, the projection optical system PL as an optical system.
A configuration for measuring the wavefront aberration of is described. As shown in FIG. 1, the movable mirror 7 is provided between the fly-eye lens 22 and the relay lens 23a of the illumination optical system 27.
The movable mirror drive unit 72 is arranged so that the movable mirror 1 can move in and out of the optical path of the exposure light EL. In the vicinity of the movable mirror 71, a measurement light source 73 that emits continuous light having a wavelength that substantially matches the wavelength of the exposure light EL as the measurement light RL is arranged. The measurement light source 73 is set so that its output has a smaller peak power than that of the exposure light EL.

The movable mirror 71 has the projection optical system P.
When measuring the aberration of L, the measurement light RL is inserted into the optical path of the exposure light EL, reflects the measurement light RL emitted from the measurement light source 73, and enters the measurement light RL from the illumination optical system 27 into the projection optical system PL. Let On the other hand, at the time of exposure, the movable mirror 71 is arranged so as to retreat from the optical path of the exposure light EL so as not to obstruct the irradiation of the exposure light EL onto the reticle R.

As the continuous light, for example, a single-wavelength laser in the infrared region or visible region emitted from a DFB semiconductor laser or a fiber laser is used, for example, with a fiber amplifier doped with erbium (or both erbium and ytterbium). A harmonic or the like that is amplified and wavelength-converted into ultraviolet light using a non-linear optical crystal is used.

For example, if the exposure light EL is ArF excimer laser light (λ = 193 nm), it is output when the oscillation wavelength of the single wavelength laser is within the range of 1.51 to 1.59 μm. It is preferable that the 8th harmonic within the range of 189 to 199 nm is the measurement light RL.
Further, 193 to 194 outputted by narrowing the oscillation wavelength within the range of 1.544 to 1.553 μm
The 8th harmonic within the nm range is more preferable as the measurement light RL because its wavelength is substantially the same as that of the ArF excimer laser light.

As shown in FIG. 1, the wafer stage W
A mounting recess 74 is formed in the Z stage 36 on ST. A wavefront aberration measuring unit 75 as a wavefront aberration measuring device for detecting the wavefront aberration of the projection optical system PL is detachably attached to the mounting recess 74. The wavefront aberration measuring unit 75 has a detection surface (incident surface on which the measurement light RL that has passed through the projection optical system PL is incident) 76 that faces the projection optical system PL, and the height of the detection surface 76 is equal to that of the wafer W. It is arranged so as to substantially match the height of the exposure surface Wf.

As shown in FIGS. 4 and 9, a collimator lens system 77 is provided inside the wavefront aberration measuring unit 75.
, Relay lens system 78, and microlens array 79
And an image pickup device (CCD) 80. The collimator lens system 77 converts the measurement light RL entering the wavefront aberration measurement unit 75 into the parallel light PB from the objective lens 81 formed of a plane parallel plate on which the detection surface 76 is formed. The objective lens 81 and the collimator lens system 77 constitute an objective optical system that faces the projection optical system PL, and the first surface thereof forms the detection surface 76 and substantially coincides with the image plane of the projection optical system PL. It is located in. The focus position Fp of the collimator lens system 77 on the projection optical system PL side is set so as to be located on the detection surface 76.

In the microlens array 79, the microlenses are arranged in a plane orthogonal to the optical axis of the parallel light PB.
The two-dimensionally arranged parallel light PB is divided into a plurality of light beams, and the divided light beams are condensed on the CCD 80 for each lens. The CCD 80 detects the position (imaging position) of the condensing point for each microlens. Then, the CCD 80 outputs a signal relating to the position of each condensing point received to the wavefront aberration detection unit 8
2 (see FIG. 1).

The wavefront aberration detecting section 82 calculates wavefront aberration information of the projection optical system PL based on the inputted information of the positions of the respective focusing points, and the information concerning the calculated wavefront aberration is subjected to the main control. Output to system 33.

Before measuring the wavefront aberration information of the projection optical system PL by the wavefront aberration measuring unit 75,
The AF sensor 45 detects the distance between the image plane of the projection optical system PL based on the reference position stored in the main control system 33 in advance and the detection plane 76 of the wavefront aberration measuring unit 75. As a result, assuming that the image of the pattern is on the image forming surface based on the reference position, the positional deviation between the image of the pattern and the detection surface 76 is detected. As the pattern here, a pinhole pattern 83 (see FIG. 8) that is arranged in the object plane of the projection optical system PL, that is, on the lower surface of the test reticle Rt and has a plurality of pinholes PH of a predetermined diameter is used.

Next, a method of measuring the wavefront aberration information of the projection optical system PL will be described. First, the wavefront aberration measuring unit 75 described above is mounted in the mounting recess 74 formed in the Z stage 36 on the wafer stage WST. And
The pinhole pattern 8 is formed on the reticle stage RST.
The test reticle Rt (see FIG. 8) on which 3 is formed is placed. Then, the movable mirror driving unit 72 causes the movable mirror 71 to enter the optical path of the exposure light EL. In this state, the measurement light source 73 emits the measurement light RL, and the measurement light RL is moved to the movable mirror 71 and the relay lenses 23a, 23.
The pinhole pattern 83 on the test reticle Rt is irradiated with light through the mirror b, the mirror 25, and the condenser lens 26. Thereby, the images of the plurality of pinholes PH are formed on the image forming surface of the projection optical system PL. In this state, wafer stage drive unit 39 drives wafer stage WST in the XY plane, and the center of detection surface 76 in wavefront aberration measurement unit 75 is imaged on the imaging surface of projection optical system PL. It corresponds to an image of a desired image height among the images of the pinhole PH.

Next, as shown in FIGS. 1 and 4, from the projection system 45a of the AF sensor 45 to the wavefront aberration measuring unit 75.
Slit light is projected onto the detection surface 76 of the
The reflected light from is received by the light receiving system 45b. Thus, the distance between the detection surface 76 of the wavefront aberration measuring unit 75 and the image plane of the projection optical system PL (here, the image formation of the projection optical system PL based on the reference position stored in advance in the main control system 33). The positional deviation of the detection surface 76 with respect to the surface) is detected. The detection information from the AF sensor 45 is sent to the main control system 33, and the main control system 33 moves the Z stage 36 in the Z direction to detect the wavefront aberration measuring unit 75 with respect to the image plane of the projection optical system PL. Adjust the position of surface 76.

As described above, when measuring the wavefront aberration information of the projection optical system PL using the wavefront aberration measuring unit 75, the Z stage 36 is moved in the Z direction based on the detection result of the AF sensor 45. , The Z stage 36 is arranged in a prestored reference position. That is, the detection surface 7 of the wavefront aberration measurement unit 75
The wavefront aberration information of the projection optical system PL is measured in a state where 6 is arranged on the image plane of the projection optical system PL based on the reference position.

As shown in FIG. 9, the measurement light RL is converted into a spherical wave SW by passing through the pinhole PH. The spherical wave SW is incident on the projection optical system PL, and when the aberration remains in the projection optical system PL, the spherical wave S is generated.
The wavefront WF of W is distorted. The spherical wave SW emitted from the projection optical system PL forms an image on the detection surface 76 of the wavefront aberration measuring unit 75 held on the wafer stage WST or in the vicinity thereof, and thereafter enters the inside of the wavefront aberration measuring unit 75. . The spherical wave SW incident on the inside of the wavefront aberration measuring unit 75 is converted into parallel light PB by the collimator lens system 77. Here, when there is no aberration in the projection optical system PL as shown in FIG. 10A, the wavefront WFpn of the parallel light PB becomes a flat surface. On the other hand, FIG.
When there is an aberration in the projection optical system PL as shown in 0 (b), the wavefront WFpa of the parallel light PB is a distorted surface.

The parallel light PB is divided into a plurality of light beams by the microlens array 79 and condensed on the CCD 80. Here, as shown in FIG. 10A, when there is no aberration in the projection optical system PL, the parallel light P
Since the wavefront WFpn of B is a plane, the parallel light PB is incident along the optical axis AXml of each lens. Therefore, the focused spot Fn of each lens exists on the optical axis AXml of each lens.

On the other hand, as shown in FIG. 10B, when the projection optical system PL has an aberration, the wavefront WFpa of the parallel light PB becomes a distorted surface as described above. Therefore, the parallel light PB incident on each lens is
Has a different wavefront inclination for each lens. Along with this, the focused spot Fa of each lens exists on the perpendicular line AXp with respect to the inclination of the wavefront, and the focused spot Fn when the aberration does not exist.
It will be displaced with respect to. The CCD 80 detects the position of each light-converging spot Fa that has been displaced.

Next, in the wavefront aberration detecting section 82, the light beam passes through the respective focused spot positions Fn in the case where the projection optical system PL given in advance has no aberration and the projection optical system PL to be measured, The detection result of each of the condensed spot positions Fa of the light beam received by the CCD 80 is compared. The wavefront aberration information in the projection optical system PL is calculated by obtaining the positional deviation amount of the focused spot position Fa for each lens with respect to the focused spot Fn based on the comparison result. Then, as shown in FIG. 11, the measured wavefront aberration information is converted into various aberration components, that is, defocus components, image point movements, by Zernike polynomials.
Expands to astigmatism, coma, spherical aberration, etc. Then
Aberrations remaining in the projection optical system PL are corrected by the image formation characteristic control unit 94 described later based on the obtained aberration components.

In this case, in the above embodiment, the wavefront aberration measuring unit 75 for the image plane of the projection optical system PL is used.
The position shift of the detection surface 76 is detected by the AF sensor 45 provided in the exposure apparatus main body. Therefore, the detection surface 76 of the wavefront aberration measuring unit 75 is set to the projection optical system P.
It is possible to accurately perform alignment with the image forming plane based on the reference position of L. Therefore, the wavefront aberration measuring unit 75
It is possible to make the detection surface 76 and the image forming surface of the projection optical system PL substantially coincide with each other.

As a result, the wavefront aberration information measured by the wavefront aberration measuring unit 75 is converted into another by using the Zernike polynomial while suppressing the defocus component which is one component in the aberration component developed by the Zernike polynomial. Aberration components, that is, image point movement, astigmatism, coma, spherical aberration, and the like can be measured. Then, based on the wavefront aberration information obtained in this way, it is possible to accurately correct the imaging characteristics of the projection optical system PL.

Next, a configuration for correcting the aberration of the projection optical system PL will be described. As shown in FIG. 1, in the projection optical system PL, the lens element 86 of the first group closest to the reticle R is fixed to the first supporting member 87, and the lens element 88 of the second group is the second supporting member 89. It is fixed to. The lens element 90 below the lens element 88 of the second group is fixed to the lens barrel portion 91. The first support member 87 is connected to the second support member 89 by a plurality of expandable / contractible (for example, three, two in FIG. 1) first drive elements 92. The second
The support member 89 is connected to the lens barrel 91 by a plurality of expandable and contractable second drive elements 93. Each drive element 9
Reference numerals 2 and 93 are connected to the imaging characteristic control unit 94.

Here, the main control system 33, based on the wavefront aberration information of the projection optical system PL input from the wavefront aberration detecting section 82, causes the image forming characteristic control section 94 to drive the drive elements 92. , 93 is commanded. This allows
The relative positions of the lens elements 86 and 88 are changed so that the image forming characteristics of the projection optical system PL are corrected.

Next, the AF sensor 45 is based on the defocus component obtained by expanding the wavefront aberration information of the projection optical system PL by the Zernike polynomial.
A method of calibrating (focus / calibration) will be described.

First, the projection system 45a of the AF sensor 45
Thus, the pattern image AF-ij of the slit-shaped opening SP-ij is formed on the detection surface 76 of the wavefront aberration measuring unit 75. In this state, the wafer stage WST is arranged at the reference position stored in advance in the main control system 33 based on the position information from the AF sensor 45. Then, an image of the pinhole PH on the test reticle Rt is formed on the detection surface 76 of the wavefront aberration measurement unit 75. Then, wafer stage drive unit 39 drives wafer stage WST in the XY plane to match the center of detection surface 76 with the image of pinhole PH at the desired image height. In this state, the wavefront aberration information of the projection optical system PL is measured and the defocus component is obtained from the wavefront aberration information according to the method described above.

The defocus component obtained at this time is
Projection optical system P generated when wafer stage WST is arranged at a reference position stored in advance in main control system 33.
A projection optical system PL for the image plane of L and the exposure surface Wf of the wafer W
It shows the amount of positional deviation in the optical axis direction (Z direction). Therefore, the main control system 33 controls the Z stage 3 by the Z stage drive unit 38 via the wafer stage control unit 42.
6 is moved in the Z direction so that the defocus component becomes zero. As a result, the detection surface 76 of the wavefront aberration measuring unit 75 is brought into a fitting state in which the detection surface 76 matches the actual image formation surface of the projection optical system PL.

Here, the wavefront aberration measuring unit 75
Is arranged such that its detection surface 76 is substantially flush with the exposure surface Wf of the wafer W placed on the Z stage 36 of the wafer stage WST. Therefore, the position of the detection surface 76 is the alignment position of the wafer W when the wafer W is exposed.

Then, the main control system 33, in this adjusted state, detects the detection surface 76 of the wavefront aberration measuring unit 75.
The position information of the image of the slit-shaped aperture SP-ij that is reflected on the CCD 80 of the AF sensor 45 and re-formed on the CCD 80 is stored as a new reference position. When the pattern on the reticle R is transferred onto the wafer W, the main control system 33 aligns the exposure surface Wf of the wafer W with the image formation surface of the projection optical system PL based on this new reference position. The Z stage 36 is moved by the Z stage drive unit 38 so as to be retracted.

Therefore, according to this embodiment, the following effects can be obtained. (B) This exposure apparatus is provided with the AF sensor 45 for detecting the position of the exposure surface Wf of the wafer W with respect to the image plane of the projection optical system PL, and the wafer stage WST is provided with the wavefront aberration information of the projection optical system PL. A desired wavefront aberration measuring unit 75 is attached. The main control system 33, which controls the operation of the entire exposure apparatus, includes the wavefront aberration measurement unit 7
The position information of the exposure surface Wf of the wafer W detected by the AF sensor is corrected on the basis of the wavefront aberration information of the projection optical system PL obtained in Step 5.

In this exposure apparatus, when detecting the position of the exposure surface Wf of the wafer W with respect to the image plane of the projection optical system PL, the position information of the exposure surface Wf is based on the wavefront aberration information of the projection optical system PL. Will be corrected. Therefore, the influence of various aberrations remaining in the projection optical system PL is eliminated from the position information of the exposure surface Wf of the wafer W, and the position information of the exposure surface Wf with respect to the image plane of the projection optical system PL is detected more accurately. can do.

(B) In this exposure apparatus, the main control system 33
Is the exposure surface Wf of the wafer W detected by the AF sensor 45.
The relative position between the image forming surface of the projection optical system PL and the exposure surface Wf of the wafer W is adjusted based on the position information of the detection surface 76 of the wavefront aberration measuring unit 75 arranged on the same plane.
Further, the main control system 33 controls the wavefront aberration measuring unit 75, adjusts the relative position between the image forming surface of the projection optical system PL and the detection surface 76 of the wavefront aberration measuring unit 75, and then adjusts the wavefront of the projection optical system PL. Aberration information is requested.

That is, in this exposure apparatus, the AF sensor 4
Based on the position information of the detection surface 76 of the wavefront aberration measuring unit 75 with respect to the image formation surface of the projection optical system PL detected in 5, the relative position between the image formation surface and the detection surface 76 is adjusted. Then, in this state, the wavefront aberration information of the projection optical system PL is obtained. Therefore, in the position information of the exposure surface Wf of the wafer W, the influence of the wavefront aberration information (defocus component etc.) of the projection optical system PL can be grasped more accurately, and the position information of the exposure surface Wf of the wafer W can be obtained. The detection accuracy can be further improved.

(C) In this exposure apparatus, the main control system 33
However, the wafer W detected by the AF sensor 45 using the defocus component of the wavefront aberration information of the projection optical system PL.
The position information of the exposure surface Wf is corrected.

In this exposure apparatus, according to the position of the detection surface 76 of the wavefront aberration measuring unit 75 arranged in the same plane as the exposure surface Wf of the wafer W with respect to the image formation surface of the projection optical system PL, the wavefront aberration information is displayed. The defocus component changes. Therefore, the separation state of the exposure surface Wf of the wafer W from the image plane of the projection optical system PL can be grasped easily and more accurately, and the image plane of the projection optical system PL and the exposure surface Wf of the wafer W can be grasped.
The relative position with respect to can be adjusted easily and more accurately.

(D) This wavefront aberration measuring unit 75
Is detachably mounted on the wafer stage WST holding the wafer W. Therefore, the position information of the exposure surface Wf of the wafer W detected by the AF sensor 45 is
Not only can it be easily and accurately corrected as required, but the wavefront aberration measuring unit 75 can be removed when the wavefront aberration measurement is unnecessary, and the projection optical system P
The entire exposure apparatus including L can be downsized.

(E) In this exposure apparatus, the AF sensor 4
5 is an exposure surface W of the wafer W within the image plane of the projection optical system PL.
A plurality of detection points AF-ij for detecting the position of f are set, that is, an image of the slit-shaped opening SP-ij is projected. Then, the plurality of detection points AF-ij
Thus, the wavefront aberration measuring unit 75 can measure the wavefront aberration information.

In this exposure apparatus, the exposure surface Wf of the wafer W is
The wavefront aberration information of the projection optical system PL is obtained at the detection point AF-ij for detecting the position of. Therefore, the position information of the exposure surface Wf of the wafer W at each detection point AF-ij is
It can be corrected more accurately.

(F) In this exposure apparatus, the main control system 33
And the exposure surface W of the wafer W stored by the AF sensor 45.
The reference position of the Z stage 36, which is a prerequisite for the position measurement of f, is corrected based on the wavefront aberration information of the projection optical system PL. Then, the alignment position of the exposure surface Wf of the wafer W with respect to the image plane of the projection optical system PL is corrected based on the corrected reference position.

Therefore, in this exposure apparatus, the AF sensor 45 can be calibrated more accurately. This allows
It is possible to prevent the exposure surface Wf of the wafer W from being unexpectedly displaced from the image plane of the projection optical system PL. In other words, the position of the exposure surface Wf of the wafer W can be detected more accurately, and the accuracy of the alignment operation of the exposure surface Wf with the image plane of the projection optical system PL is improved. Therefore, in this exposure apparatus, the exposure accuracy can be improved, and exposure of a finer pattern can be handled.

(Second Embodiment) Next, a second embodiment of the present invention will be described focusing on parts different from the first embodiment.

In the second embodiment, as shown in FIG. 12, the projection optical system PL is based on the measurement result of the wavefront aberration information of the projection optical system PL at a plurality of image height positions (detection points AF-ij). 2 shows an example in which the alignment position of the exposure surface Wf of the wafer W is adjusted when the image plane IS has a field curvature or the like. Here, FIG. 12A is an example in the case where the image plane IS of the projection optical system PL is curved, and FIG. 12B shows the image plane IS in addition to the field curvature. This is an example of the case where the image plane tilt occurs.

When the image plane IS of the projection optical system PL has a field curvature as shown in FIG. 12A, the portion of the image plane IS closest to the projection optical system PL and the wafer most. The part on the W side is the optical axis direction (Z direction) of the projection optical system PL.
Moreover, the projection optical system PL may not be within the range of the depth of focus. Particularly, in the exposure apparatus for manufacturing a semiconductor element, not only the exposure light EL has a shorter wavelength due to the remarkable miniaturization of the circuit pattern in recent years, but also the numerical aperture (NA) of the projection optical system PL is increased. It is getting bigger and bigger. Due to such an increase in the numerical aperture of the projection optical system PL, the depth of focus of the projection optical system PL is becoming shallower.

On the other hand, in the example shown in FIG. 12 (a), the main control system 33 uses the same method as in the first embodiment to determine the wavefronts of the projection optical system PL for a plurality of detection points AF-ij. Obtain aberration information. Then, the main control system 33
Calculates the defocus component from each of the wavefront aberration information and calculates the average position of the defocus component. The main control system 33 newly sets the reference position of the Z stage 36 based on this average position, and stores the new reference position again. As a result, the AF sensor 45 is calibrated.

Then, the main control system 33 uses the calibrated AF
While the sensor 45 is used to detect the exposure surface Wf of the wafer W, the Z stage drive unit 38 is controlled to set the wafer W on the alignment surface TS set based on the average position.
The Z stage 36 is driven so that the exposed surfaces Wf of the two coincide with each other. As a result, the degree of freedom of the depth of focus at each detection point AF-ij is distributed in the curved image formation surface IS, and the exposure surface Wf is limited to the focus of the projection optical system PL at all detection points AF-ij. It is possible to fit within the depth.

Further, as shown in FIG. 12B, when the image plane IS of the projection optical system PL is further tilted, the same as in FIG. 12A described above. By the way
The main control system 33 obtains the average position of the defocus component from the wavefront aberration information at the plurality of detection points AF-ij.
Then, the Z stage 36 is driven so that the exposure surface Wf of the wafer W coincides with the set alignment surface TS set based on the average position.

In this case, the main control system 33 controls the wafer W
So that the exposure surface Wf of the Z stage 36 corresponds to the image plane tilt of the projection optical system PL.
The drive amount of each of the support mechanisms 60 to 62 is changed. As a result, even when the image plane IS of the projection optical system PL has an image plane inclination as well as an image plane inclination,
The deviation of the projection optical system PL with respect to the image formation plane IS on the entire exposure surface Wf of the wafer W is suppressed to a small level, and the projection optical system PL is
Can be within the depth of focus of.

Therefore, according to the present embodiment, in addition to the effects (a) to (f) in the first embodiment,
The following effects can be obtained. (G) In this exposure apparatus, the wavefront aberration measuring unit 75
Is to obtain the wavefront aberration information of the projection optical system PL at a plurality of image height positions in the image plane of the projection optical system PL, and the main control system 33 determines the position of the wafer W surface based on the obtained plurality of wavefront aberration information. It is designed to correct information.

In this exposure apparatus, for example, the projection optical system PL
In the case where an image plane curvature, an image plane inclination, or the like is generated on the image forming plane of, the depth of focus of the projection optical system PL at each image height position is distributed based on the wavefront aberration information at a plurality of image height positions. It will be possible. Here, as the numerical aperture of the projection optical system PL is increased and the wavelength of the exposure light EL is further shortened, the depth of focus of the projection optical system PL is becoming shallower. On the other hand, by adopting the above configuration, the degree of freedom of the depth of focus at an image height position with a sufficient depth of focus within the limited depth of focus can be changed to an image height position with a small depth of focus. The relative position between the image plane of the projection optical system PL and the exposure surface Wf of the wafer W can be adjusted appropriately.

(Third Embodiment) Next, a third embodiment of the present invention will be described focusing on the points different from the above-mentioned embodiments.

In the third embodiment, as shown in FIG. 13, the pinhole pattern 101 for generating the spherical wave SW in the measurement light RL is provided on the reticle stage RST. The pinhole pattern 101 is provided on both ends of the reticle stage RST in the scanning direction (Y direction) and on the outer peripheral edge portion 103 of the reticle mounting portion 102 on which the reticle R is mounted. This pinhole pattern 101 has a plurality of pinholes PH arranged in a line in a direction intersecting the scanning direction of reticle stage RST.

When this pinhole pattern 101 is used, the reticle stage driving unit 29 causes the reticle stage driving unit 29 to form an image of the pinhole PH at a desired image height position on the image plane of the projection optical system PL. The stage RST is driven in the Y direction and the pinhole pattern 101 is arranged at a predetermined position. Then, similarly to each of the above-described embodiments, the measuring light RL is irradiated onto the pinhole PH of the pinhole pattern 101 to generate the spherical wave SW, which is incident on the wavefront aberration measuring unit 75 via the projection optical system PL. Projection optical system PL
The wavefront aberration information of is obtained.

Next, a procedure for obtaining the distribution of wavefront aberration information in the XY plane using this pinhole pattern 101 will be described. First, pinhole pattern 1
01 is arranged at a predetermined position in the Y direction, and by using some of the pinholes PH arranged in the X direction, the wavefront aberration measurement unit 75 is sequentially made to correspond to the images of the pinholes PH, and the wavefront aberration information is obtained respectively. taking measurement. Next, while moving the reticle stage RST in the Y direction by a predetermined distance,
The wavefront aberration measuring unit 75 is also moved correspondingly, and the same measurement of wavefront aberration information is repeated.

Therefore, according to this embodiment, the following effects can be obtained in addition to the effects described in (a) to (g) in each of the above embodiments. (H) In this exposure apparatus, the pinhole pattern 101 for generating the spherical wave SW at the time of measuring the wavefront aberration information is provided on the reticle stage RST. Therefore, it is not necessary to separately prepare a test reticle Rt in which the pinhole PH is formed at the time of measuring the wavefront aberration, and it is possible to reduce the number of components used at the time of measuring the wavefront aberration. Further, this pinhole pattern 101 does not need to be attached / detached outside the system depending on whether or not the wavefront aberration information is necessary, and it is possible to reduce the possibility that the pinhole PH is inadvertently deformed, and the accuracy is long-term. Wavefront aberration information can be measured. Further, since it is not necessary to attach / detach the pinhole pattern 101, the stop time of the exposure apparatus at the time of measuring the wavefront aberration information can be shortened, and the throughput of the exposure apparatus can be improved.

(Modification) The embodiment of the present invention may be modified as follows. In the first embodiment, the AF sensor 45 is based on the defocus component of the wavefront aberration information of the projection optical system PL.
After the calibration is performed, the wavefront aberration information of the projection optical system PL is measured again, and the Z stage 36 is moved in the Z direction so that the defocus component of the wavefront aberration information becomes zero. The main control system 33 then re-images the slit-shaped aperture SP on the CCD 80 of the AF sensor 45 in this state.
The position information of −ij may be stored again as the reference position. Further, these series of operations may be repeated until the defocus component of the wavefront aberration information of the projection optical system PL measured after the revision of the reference position becomes almost zero.

In this case, the AF sensor 45 can be calibrated more accurately, and the position information of the exposure surface Wf of the wafer W with respect to the image plane of the projection optical system PL can be detected with higher accuracy. it can.

In the second embodiment, some of the detection points AF-ij among the measurement results of the wavefront aberration information of the projection optical system PL at a plurality of image height positions (detection points AF-ij).
There may be a case where the defocus component in is particularly large and the degree of freedom of the depth of focus is particularly small.
In such a case, for example, the wafer W
The alignment position of the exposed surface Wf may be adjusted.

That is, the main control system 33 finds the average position of the defocus components of the other detection points AF-ij, excluding the measurement result at the detection point AF-ij having a large defocus component, and newly calculates this average position. The reference position may be stored again. Further, among the detection points AF-ij having a large defocus component, a new reference position may be stored again based on the defocus component of the detection point AF-ij having the smallest degree of freedom of the depth of focus. . However, in this case, the degree of freedom of the depth of focus at the other detection points AF-ij needs to be sufficiently secured.

In the third embodiment, as the pinhole pattern 101 on the reticle stage RST,
A plurality of rows of pinholes PH may be provided in a row in the scanning direction of reticle stage RST.

In each of the above embodiments, the wavefront aberration measuring unit 75 is used as the Z stage 36 on the wafer stage WST.
The wavefront aberration measuring unit 75 may be detachably attached to the notch provided on the side surface or the corner of the Z stage 36.

Further, the wavefront aberration measuring unit 75 is set to Z
It may be arranged such that it is directly fixedly arranged on the stage 36 or is mounted via the wafer holder 37. In this case, when measuring the wavefront aberration of the projection optical system PL, the wafer stage WST is moved along the direction of the optical axis AX of the projection optical system PL, and the detection surface 76 of the wavefront aberration measuring unit 75 is set to the above-mentioned. It is necessary to match the image plane of the projection optical system PL.

In such a case, there is no need to provide the mounting recess 74 on the wafer stage WST, and the structure of the wafer stage WST can be simplified.

In each of the above embodiments, the movable mirror 71
Is placed so that it can enter and leave the optical path of the exposure light EL, and the measurement light R
Although L is guided to the projection optical system PL, the measurement light source 73
The movable mirror 71 may be detachably attached to the illumination optical system 27. In this case, the movable mirror 71 may be a fixed type. Also,
The exposure light EL from the exposure light source 21 may be used as it is without providing the measurement light source 73 to measure the wavefront aberration of the projection optical system PL.

In such a case, the effect that the peripheral structure of the illumination optical system 27 can be simplified can be obtained. In each of the above embodiments, the Z-stage 36 is used to measure the wavefront aberration measuring unit 75 with respect to the image plane of the projection optical system PL.
Although the adjusting mechanism for adjusting the position of the detection surface 76 of is configured, the adjusting mechanism is configured by the imaging characteristic control unit 94,
By changing the position of the image plane of the projection optical system PL, the detection plane 76
It is also possible to adjust the relative position between and the image plane of the projection optical system PL.

Even in this case, the same effect as that of the above-described embodiment can be obtained. In each of the above embodiments, the image forming characteristic of the projection optical system PL is adjusted by the image forming characteristic control unit 94 and the driving elements 92, 93. However, for example, each lens element 86,
You may make it adjust between 88 and 90 with washers etc. with different thickness. Further, the projection optical system PL may be housed in a plurality of divided lens barrels, and the distance between the lens barrels may be changed.

In such a case, the effect that the peripheral structure of the projection optical system PL can be simplified can be obtained. In each of the above-mentioned embodiments, the following may be adopted as an optical member for generating the spherical wave SW in the measurement light RL incident on the projection optical system PL. That is, when measuring the wavefront aberration of the projection optical system PL, the reticle stage R is used instead of the test reticle Rt.
An opening may be formed on the ST, and the pinhole pattern 101 may be formed on the transparent plate attached so as to close the opening. In addition, the same pinhole pattern 101 may be formed on a normal device reticle.

In each of the above embodiments, the pulsed light of the excimer laser light is used as the exposure light EL used in the exposure apparatus. However, for example, a harmonic of a metal vapor laser or a YAG laser, or a g-line or h-line is used. , Continuous rays such as bright lines of ultra-high pressure mercury lamps such as i-line may be used.

In each of the above embodiments, the measurement light RL is set to D
The harmonics of the FB semiconductor laser or the fiber laser are used, but as the measurement light RL, for example, a rare gas discharge lamp such as an argon lamp, a krypton lamp, or a xenon lamp,
Xenon-mercury lamps, halogen lamps, fluorescent lamps, incandescent lamps, mercury lamps, sodium lamps, metal halide lamps, and other ultraviolet light, visible light or infrared light, or harmonics of light obtained by converting those lights into single wavelengths, Harmonics such as YAG laser light and metal vapor laser light may be used.

In each of the above-described embodiments, the method of measuring the aberration of the projection optical system PL as the wavefront aberration by the Shack-Hartmann method is adopted, but the wavefront aberration of the projection optical system PL is calculated from the optical image complex amplitude distribution by the phase restoration method. A so-called PSF (point spread function) method for obtaining

In each of the above-described embodiments, the projection optical system PL of the exposure apparatus is embodied as the test optical system for measuring the wavefront aberration, but an optical apparatus different from the exposure apparatus, such as a wafer inspection / measuring machine, is used. It may be embodied in a wavefront aberration measuring device of an optical system.

In each of the above-described embodiments, the present invention is embodied as a scanning exposure type exposure apparatus for manufacturing a semiconductor element, but may be embodied as an exposure apparatus that performs collective exposure by a step-and-repeat method, for example. . Further, it may be embodied as an exposure apparatus for manufacturing a microdevice such as a liquid crystal display element, an image pickup element, a thin film magnetic head, or an exposure apparatus for manufacturing a photomask such as a reticle.

In each of the above embodiments, the projection optical system PL
As an example, a refraction-type optical system in which all optical elements are refraction-type lenses has been described. On the other hand, the projection optical system may be composed of a reflective element (mirror) or a catadioptric system composed of a refractive lens and a reflective element. The projection optical system PL is not limited to the reduction system, and may be a unity magnification system or an enlargement system.

The exposure apparatus of each of the above embodiments can be manufactured by the following procedure, for example. That is,
The illumination optical system 27 composed of a plurality of lenses and the projection optical system PL are incorporated into the exposure apparatus main body for optical adjustment, and the reticle stage RST and wafer stage WST consisting of a large number of mechanical parts are attached to the exposure apparatus main body to perform wiring and piping. Connect. Then, the exposure apparatus is further subjected to comprehensive adjustment (electrical adjustment, operation confirmation, etc.). It is desirable to manufacture this exposure apparatus in a clean room in which the temperature and cleanliness are controlled.

The lenses 22, 23a, 23b and 26 of the illumination optical system 27 and the projection optical system P in each of the above embodiments.
Examples of the glass material of the L lens elements 86, 88, 90 include fluorite, quartz, lithium fluoride, magnesium fluoride, strontium fluoride, lithium-calcium-aluminum-fluoride, and lithium-strontium-aluminum-. Crystals such as fluoride,
Fluoride glass made of zirconium-barium-lanthanum-aluminum, quartz glass doped with fluorine,
Quartz glass doped with hydrogen in addition to fluorine, quartz glass containing an OH group, and improved quartz such as quartz glass containing an OH group in addition to fluorine can also be used.

Next, an embodiment of a method for manufacturing a microdevice (hereinafter simply referred to as “device”) using the above-described exposure apparatus in a lithography process will be described.
FIG. 14 shows devices (semiconductor elements such as IC and LSI, liquid crystal display elements, image pickup elements (CCD etc.), thin film magnetic heads,
It is a figure which shows the flowchart of the manufacturing example of a micromachine etc.). As shown in FIG. 14, first, step S201.
In the (design step), a device function / performance design (for example, a circuit design of a semiconductor device) is performed, and a pattern design for realizing the function is performed. Continuing,
In step S202 (mask manufacturing step), a mask (Rectile R or the like) on which the designed circuit pattern is formed
To produce. On the other hand, in step S203 (substrate manufacturing step), a substrate (wafer W when a silicon material is used) is manufactured using a material such as silicon or a glass plate.

Next, in step S204 (substrate processing step), using the mask and the substrate prepared in steps S201 to S203, an actual circuit or the like is formed on the substrate by a lithography technique or the like, as described later. Next, in step S205 (device assembly step), device assembly is performed using the substrate processed in step S204. This step S205 includes processes such as a dicing process, a bonding process, and a packaging process (chip encapsulation, etc.) as necessary.

Finally, in step S206 (inspection step), inspections such as an operation confirmation test and a durability test of the device manufactured in step S205 are performed. After these steps, the device is completed and shipped.

FIG. 15 is a diagram showing an example of a detailed flow of step S204 of FIG. 14 in the case of a semiconductor device. In FIG. 15, in step S211 (oxidation step), the surface of the wafer W is oxidized. In step S212 (CVD step), an insulating film is formed on the surface of the wafer W. In step S213 (electrode forming step), electrodes are formed on the wafer W by vapor deposition.
In step S214 (ion implantation step), ions are implanted in the wafer W. Steps S211 to S above
Each of 214 constitutes a pretreatment process of each stage of wafer processing, and is selected and executed in accordance with a required process in each stage.

At each stage of the wafer process, when the above-mentioned pretreatment process is completed, the posttreatment process is executed as follows. In this post-processing step, first, step S
At 215 (resist forming step), a photosensitive agent is applied to the wafer W. Subsequently, in step S216 (exposure step), the circuit pattern of the mask (reticle R) is transferred onto the wafer W by the lithography system (exposure apparatus) described above. Next, step S21.
In 7 (development step), the exposed wafer W is developed,
In step S218 (etching step), the exposed member other than the portion where the resist remains is removed by etching. Then, in step S219 (resist removing step), the resist that has become unnecessary after etching is removed.

By repeating these pre-processing and post-processing steps, multiple circuit patterns are formed on the wafer W. If the device manufacturing method of the present embodiment described above is used, the exposure apparatus described above is used in the exposure step (step S216), and the exposure light E in the vacuum ultraviolet region is obtained.
The resolution can be improved by L, and the exposure amount can be controlled with high accuracy. Therefore, as a result, a highly integrated device having a minimum line width of about 0.1 μm can be manufactured with high yield.

[0131]

As described above in detail, according to the first and eighth aspects of the present invention, it is possible to more accurately detect the position information of the surface to be detected with respect to the image plane of the optical system. .

According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, the detection accuracy of the position information of the surface to be inspected can be further improved.
According to the invention of claim 3 of the present application, in addition to the effect of the invention of claim 1 or 2, adjustment of the relative position between the imaging surface of the optical system and the surface to be inspected is performed. It can be done easily and more accurately.

According to the invention of claim 4 of the present application, in addition to the effect of the invention of any one of claims 1 to 3, the surface to be detected detected by the detection mechanism The position information of can be easily and accurately corrected as needed. In particular, when the wavefront aberration measuring mechanism is detachably mounted on the member-to-be-inspected holding mechanism, the size of the entire apparatus including the optical system can be reduced.

According to the invention described in claim 5, in addition to the effect of the invention described in any one of claims 1 to 4, in a limited depth of focus, The relative position between the image plane of the optical system and the surface to be inspected can be adjusted appropriately.

According to the invention of claim 6, in addition to the effect of the invention of claim 5, the position of the surface to be detected at the detection position for detecting the position of the surface to be detected. The information can be corrected more accurately.

According to the invention described in claim 7, the focusing device can be calibrated more accurately. Further, according to the invention of claim 9 of the present application, it is possible to improve the exposure accuracy, and it is possible to cope with the exposure of a finer pattern.

According to the tenth aspect of the present invention, it is possible to manufacture a highly integrated device with a high yield.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of an exposure apparatus of the present invention.

FIG. 2 is a schematic configuration diagram mainly showing the AF sensor of FIG.

FIG. 3 is a schematic configuration diagram showing the Z stage of FIG. 1 and its control configuration.

FIG. 4 is a cross-sectional view showing the internal configuration of the wavefront aberration measurement unit of FIG.

5 is a plan view showing an image of a slit-shaped aperture projected on a shot area of the wafer of FIG.

FIG. 6 is a plan view showing the pattern forming plate of FIG.

FIG. 7 is an explanatory diagram showing an arrangement of the light receiving sensors of FIG.

FIG. 8 is a plan view showing the test reticle shown in FIG.

9 is an explanatory diagram related to a method of measuring wavefront aberration by the wavefront aberration measuring unit of FIG.

FIG. 10A is an explanatory diagram relating to a measurement state of wavefront aberration in the wavefront aberration measurement unit when there is no aberration in the projection optical system and in FIG. 10B when there is aberration in the projection optical system.

FIG. 11 is an explanatory diagram regarding development of an aberration component by a Zernike polynomial.

12A and 12B show an image plane in the projection optical system in the second embodiment of the exposure apparatus according to the present invention when the image plane is curved, and FIG. Explanatory drawing regarding the case where inclination has arisen.

FIG. 13 is a plan view showing a reticle stage in a third embodiment of the exposure apparatus of the present invention.

FIG. 14 is a flowchart of an example of manufacturing a micro device.

15 is a detailed flowchart of the substrate processing of FIG. 14 in the case of a semiconductor device.

[Explanation of symbols]

30 ... Focus position detection system (AF sensor) as a detection mechanism, 33 ... Main control system that constitutes a correction mechanism and control mechanism, 36 ... Z that constitutes an adjustment mechanism and a member-to-be-inspected holding mechanism
Stage, 75 ... Wavefront aberration measuring unit as wavefront aberration measuring device, AF-ij ... Detection point (image of slit-shaped aperture) constituting detection position, IS ... Image plane, PL ... Projection optical system as optical system, R ... Reticle as a mask, W ... Substrate and wafer as a member to be inspected, Wf ... Exposure surface forming a surface to be inspected.

Continued front page    F term (reference) 2F065 AA03 BB02 BB27 DD02 DD05                       EE08 FF04 FF10 FF51 GG04                       GG05 JJ03 JJ05 JJ26 LL02                       LL10 LL12 LL30 MM02 PP11                 5F046 AA25 BA04 BA05 CB12 CB17                       CB25 CC01 CC02 CC03 CC05                       CC16 DA13 DA14 DB01 DB05                       DC10 DC12

Claims (10)

[Claims] 1. A surface position detecting device having a detection mechanism for detecting the position of a surface to be inspected with respect to an image forming surface of an optical system, wherein a wavefront aberration measuring mechanism for obtaining wavefront aberration information of the optical system and the wavefront aberration measurement. A surface position detection device comprising: a correction device that corrects position information of the surface to be detected detected by the detection mechanism based on wavefront aberration information obtained by the mechanism. 2. An adjusting mechanism that adjusts a relative position between an image forming surface of the optical system and the surface to be inspected based on position information of the surface to be inspected detected by the detecting mechanism, and the wavefront aberration measurement. The surface position detection mechanism according to claim 1, further comprising: a control mechanism that controls a mechanism to obtain wavefront aberration information of the optical system after the relative position is adjusted by the adjustment mechanism. 3. The correction mechanism corrects the position information of the surface to be detected detected by the detection mechanism using a defocus component of the wavefront aberration information. The surface position detection device according to claim 2. 4. The wavefront aberration measuring mechanism, with respect to a test member holding mechanism for holding a test member having the test surface,
The surface position detection device according to any one of claims 1 to 3, wherein the surface position detection device is fixedly or detachably mounted. 5. The wavefront aberration measuring mechanism obtains wavefront aberration information of the optical system at a plurality of measurement positions within an image forming plane of the optical system, and the correction device uses the obtained plurality of wavefront aberration information. The surface position detection device according to claim 1, wherein the position information of the surface to be inspected is corrected based on the surface position detection device. 6. The detection mechanism sets a plurality of detection positions for detecting the position of the surface to be inspected in an image formation plane of the optical system, and at least one of the plurality of measurement positions is set. The surface position detection device according to claim 5, wherein a measurement position coincides with at least one of the plurality of detection positions. 7. A detection mechanism for detecting the position of the surface to be inspected with respect to the image formation surface of the optical system, and an image formation surface of the optical system based on position information of the surface to be detected detected by the detection mechanism. In an adjusting method of a focusing device including an adjusting mechanism for adjusting a relative position to the surface to be inspected, wavefront aberration information of the optical system is obtained, and the optical system in the adjusting mechanism is obtained based on the obtained wavefront aberration information. A method for adjusting a focusing device, which comprises correcting the relative position between the image forming surface of the object and the surface to be inspected. 8. A surface position detecting method for detecting a position of a surface to be detected with respect to an image forming surface of an optical system, wherein position information of the surface to be detected to be detected is corrected based on wavefront aberration information of the optical system. A surface position detection method characterized by: 9. An exposure device for transferring a pattern on a mask onto a substrate via a projection optical system, comprising the surface position detection device according to claim 1. An exposure apparatus, wherein the surface position detection device detects the position of the surface of the substrate with respect to the image formation surface of the projection optical system. 10. A method of manufacturing a device including a lithography step, wherein exposure is performed using the exposure apparatus according to claim 9 in the lithography step.