JPH0766120A - Surface position detector and fabrication of semiconductor employing it - Google Patents

Abstract

PURPOSE:To locate the entire exposing region within the allowable depth of focus of a projection optical system even if the wafer surface is inclining by varying the information relating to the heights of a plurality of measuring points in the exposing region on the surface of a wafer according to the size of the exposing region while retaining the similarity in the relative position of the plurality of measuring points. CONSTITUTION:Correction optical systems 12-16 are provided for respective measuring point 19-23 and the projective magnifications on the detection planes 17 thereof are substantially equalized. The position of a pinhole image incident to the detection plane 17 is varied depending on the position of the measuring points 19-23 on the surface of a wafer 2. The measuring points 19-23 on the surface of wafer are conjugated with the detection plane of a photoelectric converting means SC through a projection means SB. Consequently, the position of pinhole image on the detection plane 17 is varied depending on the height of the measuring points 19-23. The photoelectric converting means SC detects information relating the incident position of pinhole image on the detection plane 17 and delivers the information to a focus control means 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure apparatus for manufacturing a semiconductor element on a wafer surface when an electronic circuit pattern formed on the reticle surface is reduced and projected onto the wafer surface by a projection optical system. The surface position detecting device capable of detecting the surface position information (height information) of a plurality of points and easily positioning the exposure area of the wafer on the best image forming surface of the projection optical system and obtaining a good projection image. And a method for manufacturing a semiconductor device using the same.

[0002]

2. Description of the Related Art In recent years, projection exposure apparatuses for manufacturing semiconductor devices have been required to miniaturize electronic circuit patterns, for example, submicron to half-micron miniaturization and high integration. Accordingly, the projection optical system is required to have a higher resolution than ever before. Therefore, for example, in the projection optical system, the high N.V. A wavelength is shortened and the exposure wavelength is shortened.

Generally, in order to increase the resolution of a projection optical system, N. When A is increased, the allowable depth of focus for pattern projection becomes shallower. For this reason, many projection exposure apparatuses use a surface position detection device that detects the focal plane position of the projection optical system. With respect to this surface position detection device, not only is the height position (surface position) information of the exposure area (shot area) on the wafer surface on which pattern transfer is performed detected and adjusted, but also on the wafer surface on which pattern transfer is performed. There is a demand for being able to simultaneously detect and adjust the inclination of the exposure area.

For example, in Japanese Examined Patent Publication No. 2-10361, the height information of the central portion of the exposure area is detected and adjusted by an oblique incident height position detection optical system, and an oblique incident inclination detection optical provided separately from this is detected. An oblique incidence method has been proposed in which a system (collimator) detects and adjusts the tilt in the exposure area.

Further, the applicant of the present invention discloses in JP-A-4-354320, an exposure area (shot area) on the wafer surface.
A height position detection optical system for measuring a plurality of points is provided, and an inclination and a height position in an exposure area are calculated from height position information of the plurality of points, and an adjusted device for manufacturing a semiconductor element is proposed. .

[0006]

Generally, if the exposure area on the wafer surface for pattern transfer has unevenness or a smooth inclination, it is very difficult to position the exposure area within the allowable depth of focus of the projection optical system.

In the system proposed by the present applicant in Japanese Patent Laid-Open No. 4-354320, which uses an oblique projection optical system on an exposure area to detect height positions of a plurality of points, a plurality of measurement points are used. The mutual position of is fixed. Therefore, the area where multiple measurement points exist and the exposure area do not always match, and as the allowable depth of focus narrows, pattern transfer can be performed by changing the positions of multiple measurement points according to the size of the exposure area. A mechanism for positioning the entire exposure area within the allowable depth of the projection lens is desired.

However, in the system for detecting the height positions of a plurality of points by using the grazing incidence projection optical system, as proposed by the present applicant in Japanese Patent Laid-Open No. 3-246411, Therefore, it is necessary to provide a separate correction optical system, and the spatial arrangement of the correction optical system is largely restricted, and special consideration is required.

According to the present invention, the height information (surface position information) of a plurality of points in the exposure area on the wafer surface is adjusted to the size of the exposure area in consideration of the restriction on the spatial arrangement. It is detected by a surface position detection device having a variable mechanism that makes the mutual positions variable, and as a result, even if the wafer surface has an uneven shape or is tilted, the entire exposure area on the wafer surface is projected by the projection optical system. It can be easily located within the allowable depth of focus of. Accordingly, it is an object of the present invention to provide a surface position detecting device capable of manufacturing a high density semiconductor device and a method of manufacturing a semiconductor device using the surface position detecting device.

[0010]

The surface position detecting apparatus of the present invention comprises: (1-1) Light irradiating means for irradiating a plurality of light beams on a plurality of positions on a surface to be inspected in a diagonal direction and reflection on the surface to be inspected. Surface position detection having a plurality of light beams incident on the light receiving element surface, detecting the incident position information of the plurality of light beams on the light receiving element surface, and obtaining surface position information of the surface to be detected. In the apparatus, the light irradiating means has a first variable mechanism for similarly changing the incident positions of the plurality of light beams on the surface to be inspected, and the detecting means receives the light beams of the plurality of light beams. It is characterized in that it has a second variable mechanism for making the incident position on the element surface relatively variable.

In particular, in the second variable mechanism, even if the incident positions of the plurality of light beams on the surface to be measured change in a similar manner, the incident positions of the plurality of light beams on the light receiving element surface become constant. That is, the first variable mechanism includes a first lens system of both-side telecentricity and a plurality of first correction systems provided for each of the plurality of light beams, and the first lens system and the plurality of first lens systems. At least a part of one correction system is movable in the optical axis direction, and the second variable mechanism includes a second lens system that is telecentric on both sides, and a plurality of second lenses provided for each of the plurality of light beams.
It has a correction system, and at least a part of the second lens system and the plurality of second correction systems is movable in the optical axis direction.

Further, as a method of manufacturing a semiconductor element of the present invention, (1-2) when a semiconductor element is manufactured through a process of projecting and exposing a circuit pattern of a reticle onto a wafer surface by a projection optical system, A first variable mechanism that makes a plurality of light beams incident on a plurality of positions in a shot area on a surface from an oblique direction by similarly changing the incident positions, and a plurality of light beams reflected by the shot area on the wafer surface are incident on a light receiving element. Is incident on the light receiving element surface by detecting incident position information of the plurality of light beams to obtain surface position information of a shot area of the wafer surface. It is characterized in that the shot area is positioned on the image plane of the projection optical system based on position information, and then the circuit pattern of the reticle is projected and exposed onto the shot area on the wafer surface by the projection optical system. .

In particular, the second variable mechanism keeps the incident positions of the plurality of light beams on the light receiving element surface constant even if the incident positions of the plurality of light beams on the wafer surface change. That is, the first variable mechanism has a first lens system of both-side telecentricity and a plurality of first correction systems provided for each of the plurality of light beams, and the first lens system and the plurality of first correction systems are provided. At least a part of them is movable in the optical axis direction, and the second variable mechanism is a two-sided telecentric second
A lens system and a plurality of second correction systems provided for each of the plurality of light beams are provided, and at least a part of the second lens system and the plurality of second correction systems is movable in the optical axis direction. It is characterized by being present.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of the essential portions of a first embodiment of the present invention, and FIG.
FIG. 2 is an enlarged explanatory view of a part of FIG. 1.

In FIG. 1, 1 is a reduction type projection optical system (projection lens system), and Ax is the optical axis of the projection optical system 1. 1a
Is a reticle, a circuit pattern is formed on the surface thereof, and the reticle is placed on the reticle stage 1b. 1
Reference numeral c is an illumination system, which uniformly illuminates the surface of the reticle 1a. The projection optical system 1 reduces and projects the circuit pattern on the surface of the reticle 1a onto the surface of the wafer 2. The wafer 2 is adsorbed and fixed on the surface of the wafer stage 3. The wafer stage 3 is movable in two directions (x, y directions) in a plane (in an xy plane) orthogonal to the optical axis Ax direction (z direction) of the projection optical system 1 and the optical axis Ax, and The tilt can be adjusted with respect to a plane (xy plane) orthogonal to Ax. Thus, the surface position of the wafer 2 placed on the surface of the wafer stage 3 can be adjusted arbitrarily. A stage control device 4 drives and controls the wafer stage 3 based on a signal from a focus control device 18, which will be described later.

SA is a light irradiation means, SB is a projection means, SC
Is photoelectric conversion means, and these constitute a part of a surface position detecting device for detecting surface position information of the surface of the wafer 2.
The projection means SB and the photoelectric conversion means SC are combined with the detection means SB.
It constitutes C.

In this embodiment, a circuit pattern on the surface of the reticle 1a is projected on the wafer 2 by the projection optical system 1 by using a surface position detecting device.
When projecting onto the surface, the wafer stage 3 is drive-controlled so that the exposure area (shot area) on the surface of the wafer 2 is located within the allowable depth of focus of the projection optical system 1. Then, the wafer stage 3 is sequentially moved on the XY plane, whereby a rectangular pattern area (shot) 39 (for example, 20
mm × 20 mm) are sequentially formed on the surface of the wafer 2.

Next, each element of the surface position detecting device of this embodiment will be described. First, the light irradiation means SA for making a plurality of light beams incident on the surface of the wafer 2 will be described.

Reference numeral 5 denotes a light source, which is composed of a white lamp or an illumination unit configured to emit light having a plurality of different wavelengths. Reference numeral 6 denotes a collimator lens, which emits the light flux from the light source 5 as a parallel light flux whose cross-sectional intensity distribution is substantially uniform. Reference numeral 7 denotes a prism-shaped slit member, which has a plurality of openings (five pinholes) 71 to 75.

120, 130, 140, 150, 160
Is a correction optical system (first correction system), and the magnification, the resolution, the detection accuracy, etc. when detecting the height position information of a plurality of measurement points on the wafer surface are substantially equal to each other.
Regarding the correction optical system, the applicant of the present invention has disclosed that
Since it is proposed in Japanese Patent No. 246411, details thereof will be omitted.

Reference numeral 8 denotes a lens system (first lens system), which comprises both telecentric systems. Correction optical system 12 in which five independent light beams 71a to 75a that have passed through the plurality of pinholes 71 to 75 of the slit member 7 are provided for each optical path.
Images are formed at positions 710, 720, 730, 740, and 750 on the same plane at 0, 130, 140, 150, and 160. Then, the lens system 8 guides light through the mirror 9 to the five measurement points 19 to 23 on the surface of the wafer 2 at equal angles.

At this time, the projected images are made to be pinhole images having substantially the same size. Further, this lens system 8 has an N.V. It has an aperture stop 40 for aligning A. In this embodiment, each of the above elements 5,
6,7,8,9,120,130,140,150,1
The light irradiation means SA is composed of 60.

In this embodiment, the incident angle φ of each light beam from the light irradiation means SA on the wafer 2 surface (the angle formed by the perpendicular line standing on the wafer surface) is φ = 70 ° or more. As shown in FIG. 2, a plurality of pattern areas (exposure area shots) 39 are arranged on the wafer 2 surface. 5 that passed through the lens system 8
The two light beams 71a to 75a are incident on the measurement points 19 to 23 of the pattern region 39, which are independent of each other.

The five light beams 71a to 75a incident on the surface of the wafer 2 are perpendicular to the wafer 2 (direction of the optical axis Ax).
As shown in FIG. 2, when observed from above, they are incident on the surface of the wafer 2 from the direction rotated by θ ° in the XY plane from the X direction (shot arrangement direction). In addition, the five pinholes 71 to 71 of the slit member 7
75 correction optical systems 120, 130, 140, 150, 1
Positions 710, 720, 730, 74 formed at 60
0 and 750 are provided on the same plane conjugate with the wafer 2 so as to satisfy the Scheimpflug condition with the surface of the wafer 2. Further, the size and shape of the pinholes 71 to 75 of the pinhole member 7, the correction optical system 120, 130, 140, 15
0, 160, and the lens system 8 are set so as to form pinhole images of substantially the same size on the surface of the wafer 2.

In this embodiment, each of the above elements 5, 6, 7, 1
A plurality of light fluxes (pinholes) are made incident on the surface of the wafer 2 by the light irradiation means SA composed of 20, 130, 140, 150, 160, 8, and 9. In the present embodiment, the number of measurement points on the surface of the wafer 2 is not limited to five, and any number may be used.

Next, a plurality of reflected light beams from the surface of the wafer 2 are converted into C
The projection means SB that guides light onto the detection surface (light receiving element surface) 17 of the photoelectric conversion means SC as a position detection element made of a CD to form an image will be described.

Reference numeral 11 denotes a light receiving lens (second lens system), which is composed of both telecentric systems. The five reflected light beams from the surface of the wafer 2 are reflected by the mirror 10 and enter the light receiving lens 11.

Reference numeral 41 denotes a stopper diaphragm provided in the lens system 11, which is a height generated when each light beam is reflected at each measurement point 19, 20, 21, 22, 23 on the wafer 2 on which a pattern is formed. The next diffracted light is cut.

The light-receiving lens 11 has measurement points 19-2.
3, the pinhole image is formed at each position 24-28. The light fluxes from the pinhole images at the positions 24 to 28 are independently provided with five correction optical systems (second correction systems) 12 to 16
The light is entering.

Since the light receiving lenses 11 of the correction optical systems 12 to 16 are both telecentric systems, their optical axes are parallel to each other and the pinhole images formed at the respective positions 24 to 28 are detected by the photoelectric conversion means SC. The images are re-imaged on the surface 17 so that the spot lights have the same size. The photoelectric conversion means SC is composed of a single two-dimensional CCD. In this embodiment, the above-mentioned elements 10, 11, 12 to 16 constitute a projection means SB.

The correction optical systems 12 to 16 each have a plane-parallel plate having a predetermined thickness and a lens system.
It is coaxial or eccentric with respect to the optical axis of 1. At this time, the plane parallel plate is used to correct the optical path length of each lens system. The lens system is provided to correct the image forming magnifications (projection magnifications) on the detection surface 17 of the measurement points 19 to 23 so as to be substantially equal to each other.

That is, in the oblique incidence imaging optical system in which a plurality of light beams are obliquely incident on the wafer surface as in this embodiment, the light receiving lens 1 is used.
When a plurality of measurement points 19 to 23 having different distances from 1 are imaged on the detection surface 17 of the photoelectric conversion means SC, the imaging magnifications thereof are different from each other.

Therefore, in this embodiment, correction optical systems 12 to 16 are provided for the respective measurement points, and the respective measurement points 19 to 2 are provided.
The projection magnifications of No. 3 and No. 3 on the detection surface 17 are made substantially equal (this correction optical system is described in detail in Japanese Patent Application Laid-Open No. 3-246411 of the present applicant).

At this time, each measurement point 19 on the wafer 2 surface is measured.
The position of the pinhole image (spot light) incident on the detection surface (light receiving element surface) 17 is changed depending on the surface positions (height direction, optical axis Ax direction) of 23. The photoelectric conversion means SC detects the position change of the pinhole image at this time. As a result, in this embodiment, the surface position information of the measurement points 19 to 23 on the wafer 2 surface can be detected with the same accuracy.

Further, the measurement points 19 to 23 on the wafer 2 surface and the detection surface 17 of the photoelectric conversion means SC are conjugated with each other via the projection means SB (for each measurement point 19 to 23). I am performing fall correction). As a result, the position of the pinhole image on the detection surface 17 does not change due to the local inclination of each of the measurement points 19 to 23, and the optical axis A on the surface of the wafer 2 does not change.
The position of the pinhole image on the detection surface 17 is changed in response to the local change of the height position of each measurement point in the x direction, that is, the height of the measurement points 19 to 23. The photoelectric conversion means SC detects the incident position information of the pinhole image incident on the detection surface 17. The incident position information of the pinhole image at each measurement point 19 to 23 obtained by the photoelectric conversion unit SC is input to the focus control unit 18.

The focus control means 18 is a photoelectric conversion means S.
Height information (surface position information) of each measurement point 19 to 23 from C
Then, the position information of the surface of the wafer 2, that is, the position in the optical axis Ax direction (z direction), the inclination with respect to the XY plane, and the like are obtained.

Then, a signal relating to the drive amount of the wafer stage 3 is input to the stage controller 4 so that the surface of the wafer 2 substantially coincides with the projection surface of the reticle 1a by the projection optical system 1.

On the other hand, the displacement of the wafer stage 3 in the xy directions is measured by a known method using a laser interferometer (not shown), and a signal indicating the amount of displacement of the wafer stage 3 is transmitted from the laser interferometer via a signal line. Input to the stage control device 4.

The stage control device 4 controls the position of the wafer stage 3 in the xy directions, and at the same time, drives and controls the wafer stage 3 in the z direction in response to an input signal from the focus control means 18, whereby the position of the wafer 2 is determined. I am adjusting my posture.

Next, the arrangement features of the respective elements when a light beam is made incident on a plurality of measurement points (19 to 23) on the surface of the wafer 2 to form a pinhole image in this embodiment will be described.

A plurality of measurement points 19 to 23 on the surface of the wafer 2 in this embodiment are set at four corners of the rectangular pattern area (shot) 39 of the wafer 2 and substantially the centers of the four corners as shown in FIG. is doing. Then, the light irradiation means SA causes an angle θ (θ in the figure) from the X direction of the rectangular pattern area 39.
= 22.5 °) Each pinhole 71 to
The luminous flux of 75 is emitted to each of the measurement points 71 to 75.

At this time, each pinhole 7 of the light irradiation means SA
The light beams from 1 to 75 are made incident on the surface of the wafer 2 so as to be observed independently of each other when observed from the vertical direction of the wafer 2.

The mechanism for changing the mutual positions of a plurality of measurement points in this embodiment will be described below separately for the mechanism in the light irradiation means SA and the mechanism in the detection means SBC. The lens system 8 of the light irradiation means SA is composed of four lenses 81 to 84 as shown in FIGS. When changing the position of the measurement point, the positions of the lenses 81 to 84 and the aperture stop 40 are changed in the optical axis direction by the first variable mechanism to change the projection magnification.

For example, when the measurement points 19 to 23 are arranged so that they are contained in the exposure area 39 having the size shown in FIG. 3A, the lens system 8 is in the state shown in FIG. In the same figure, for simplicity, only the image formation state of the measurement points 19 and 21 is shown. (Other measurement points 20, 22, and 23 are the same as the measurement point 19.) At this time, the correction optical systems 120 to 160 are shown in FIG.
In this state, only those corresponding to the measurement points 19 and 21 are shown. Although the correction optical system 140 is fixed, the correction optical systems 120, 130, 150, 160 are movable in the optical axis direction with the same structure (first variable mechanism).

At this time, the pinhole 71 of the slit member 7
˜75 is an image forming point 710 by the correction optical system 120 to 160.
To 750 are image-forming magnifications β ₁₂₀ (71) to β ₁₆₀ (75), respectively. The image forming points 710 to 750 are imaged on the measuring points 19 to 23 by the lens system 8, and the image forming magnifications at this time are set to β.
₈ (710) to β ₈ (750). In this embodiment, the composite magnifications are set to the same value, β (SA).

That is, β (SA) = β ₁₂₀ (71) × β ₈ (710) = β ₁₃₀ (72) × β ₈ (720) = β ₁₄₀ (73) × β ₈ (730) = β ₁₅₀ (74 ) × β ₈ (740) = β ₁₆₀ (75) × β ₈ (750).

In addition, in FIG. 4, the luminous flux 73a and the other measuring points 19 for the measuring point 21 which is telecentric on both sides,
Luminous fluxes 71a, 72a, 74 corresponding to 20, 22, 23
a and 75a on the incident side (light source 6 side) are D ₈ (7
10), D ₈ (720), D ₈ (740), D ₈ (750), and the distances on the emitting side (wafer 2 side) are D ₈ (19), D ₈ (20), and D, respectively.
₈ (22) and D ₈ (23) (only D ₈ (710) and D ₈ (19) are shown) D ₈ (19) / D ₈ (710) = D ₈ (20) / D ₈ (720 ) = D ₈ (22) / D ₈ (740) = D ₈ (23) / D ₈ (750) = β ₈ (730).

Next, a case will be described in which the positions of the measurement points 19 to 23 are changed so as to be contained in the exposure area 39 having the size shown in FIG. 3B. Figure 4 before changing the position
In this state, the image forming point 7 of the light beams 71a and 73a on the light source 6 side is
The plane 700 on which 10, 730 exists and the plane 200 on which the imaging points 190 and 210 on the surface to be inspected exist share the same line of intersection with the plane 800 in which the aperture stop 40 in the lens system 8 exists. . (It is a state where the Sch-eimpflug's condition is satisfied.) At this time, the measurement points 19 and 21 of the surface to be inspected coincide with the image forming points 190 and 210, and the wafer surface 2 which is the surface to be inspected is the image forming point It coincides with the plane 200 on which 190 and 210 exist.

In the state of FIG. 5, the lenses 81 to 84 and the aperture stop 4 are arranged so that the lens system 8 changes the projection magnification while maintaining the telecentric state on both the incident side and the emitting side.
The image formation state when the position of 0 is changed in the optical axis direction is shown. In the figure, the plane 200 on which the image formation points 190 and 210 are present is the plane 70 on which the image formation points 710 and 730 are present.
0 and a plane 80 in which the aperture stop 40 in the lens system 8 exists
Since they are formed so as to share the same line of intersection with 0, they do not coincide with the wafer surface 2, which is the surface to be inspected. In this state, the image defocuses at the remaining measurement points (only the measurement point 19 is shown) except the measurement point 21 on the wafer 2.

Therefore, as shown in the state of FIG. 6, the lenses 81 to 84, so that the projection magnification becomes the state of FIG. 3B while maintaining the telecentric state on both the incident side and the outgoing side.
The positions of the aperture stop 40 and the aperture stop 40 are changed in the optical axis direction, and at the same time, the image forming point 710 of the light beam 71a on the light source side is changed so that all the measurement points 19 to 23 are imaged on the wafer 2.

At this time, image forming points 710 and 730 on the light source 6 side
Plane 770 in which the aperture exists and the aperture stop 4 in the lens system 8.
The plane 200 on which the image forming points 190 and 210 that share the same line of intersection with the plane 800 on which 0 exists is the same as the wafer surface 2 which is the surface to be inspected (the plane 700 in FIG. , The plane where the image formation points 710 and 730 in FIG. 5 exist.)

[0052] When changing the light source 6 side of the imaging point 710 of the light beam 71a, each imaging magnification of the measuring points 19 to 23 by the lens system 8 for imaging point 710-750 in the state of FIG. 6 beta _'8 (71) ~β 'and ₈ (75). Further, the correction optical systems 120 to 160 for the slits 71 to 75 in the state of FIG.
Of the image forming points 710 to 750 by β ′ ₁₂₀
(710) to β ′ ₁₆₀ (750), and the composite magnifications of the respective values are the same, β (SA).

[0053] That is, β '(SA) = β ' 120 (71) × β '8 (710) = β' 130 (72) × β '8 (720) = β' 140 (73) × β '8 ( _{730) = β '150 (74} ) × β' 8 (740) = β '160 (75) × β' 8 (750) of such relationship is established, the correction optical system 120, 130,
150 and 160 are changed in the optical axis direction.

Even if the measurement points 19 to 23 are arranged at the magnification shown in FIG. 3B, the lens system 8 is arranged as shown in FIG. 6 and the correction optical systems 120 to 160 are arranged as shown in FIG.
The images of the slits 71 to 75 are the points 710 to 7 on the plane 770.
50 and measurement points 19 to 23 on the wafer 2 which is the surface to be inspected
Is imaged.

Further, in FIGS. 5 and 6, the luminous flux 73a corresponding to the measurement point 21 which is telecentric on both sides and the luminous fluxes 71a and 72 corresponding to the other measurement points 19, 20, 22, and 23.
Letting the distances of a, 74a, and 75a on the emitting side (wafer 2 side) be D' ₈ (19), D' ₈ (20), D' ₈ (22), and D' ₈ (23), respectively.
( 'Illustrated only ₈ (19) D D ₈ and _{(710) D)' 8 (} 19) / D 8 (710) = D '8 (20) / D 8 (720) = D' 8 (22) / D ₈ (740) = D relationship _{'8 (23) / D 8} (750) = β' 8 (730) is established.

Here, the lens system 8 is placed on the incident side (the light source 6 side).
The telecentric correction optical system 120-
Since 160 is parallel to the optical axis direction, it is easy to create a mechanical moving mechanism, and the correction optical systems 120 to 16
This is because even if 0 moves, they do not interfere with each other.

Further, the lens system 8 is telecentric on the emitting side (wafer 2 side), as described above, because of the distance intervals D '(19), D' (20), D '(22), D' (23). This is to make the rate of change of all equal to β ′ ₈ (730), and this makes it possible to change the relative intervals of the measurement points 19 to 23 while keeping the similar shape.

On the other hand, the lens system 11 of the detecting means SBC is
As shown in FIGS. 9 and 10, it is composed of four lenses 111 to 114. When changing the position of the measurement point, the positions of the lenses 111 to 114 and the stopper diaphragm 41 are changed in the optical axis direction by the second variable mechanism to change the projection magnification.

First, a case will be described in which the measurement points 19 to 23 are arranged so as to fit in the exposure area 39 having the size shown in FIG. 3 (A). At this time, the lens system 11 is shown in FIG.
It is in the state of. In the figure, measurement point 1 is shown for simplicity.
Only the imaging state of 9, 21 is shown (measurement points 20, 2
The measurement points 2 and 23 are the same as the measurement point 19. ).

The correction optical systems 12 to 16 at this time are shown in FIG.
In this state, only those corresponding to the measurement points 19 and 21 are shown. Although the correction optical system 14 is fixed, the other correction optical systems 12, 13, 15, 16 have the same structure (second variable mechanism) and are movable in the optical axis direction.

Here, the measuring points 19 to 23 are the lens system 11.
The image forming magnification when forming an image on the image forming points 24 to 28 by
Imaging magnification when each and _{β 11 (19) ~β 11 (} 23), imaging points 24 to 28 by the correction optical system 12 to 16, for imaging the light incident positions 29-33 on the position detecting element 17 , Β ₁₂ (2
4) to β ₁₆ (28). In the present embodiment, the composite magnifications are set to the same value, β (SBC).

That is, β (SBC) = β ₁₁ (19) × β ₁₂ (24) = β ₁₁ (20) × β ₁₃ (25) = β ₁₁ (21) × β ₁₄ (26) = β ₁₁ (22 ) × β ₁₅ (27) = β ₁₁ (23) × β ₁₆ (28).

Further, the luminous flux 73a corresponding to the measurement point 21 which is telecentric on both sides in FIG.
Light fluxes 71a, 72a corresponding to 9, 20, 22, 23,
The distance on the incident side (wafer 2 side) of 74a and 75a is D
The distances of ₁₁ (19), D ₁₁ (20), D ₁₁ (22), D ₁₁ (23) and the emission side (light source 6 side) are D ₁₁ (24), D ₁₁ (25), D ₁₁ (27), respectively. ), D
₁₁ (28) (only D ₁₁ (24) and D ₁₁ (19) are shown) D ₁₁ (24) / D ₁₁ (19) = D ₁₁ (25) / D ₁₁ (20) = D ₁₁ (27 ) / D ₁₁ (22) = D ₁₁ (28) / D ₁₁ (23) = β ₁₁ (21).

Next, a case will be described in which the positions of the measurement points 19 to 23 are changed so as to be contained in the exposure area 39 having the size shown in FIG. 3B.

In the state of FIG. 9 before changing the position, the image forming points 24 of the light beams 71a and 73a on the position detecting element 17 side,
A plane 1200 in which 26 exists and an image forming point 19 on the surface to be inspected
The plane 200 in which 0 and 210 exist shares the same ray with the plane 1100 in which the stopper diaphragm 41 of the lens system 11 exists (a state in which the Scheimpflug's condition is satisfied).

At this time, the measurement points 19 and 21 on the surface to be inspected coincide with the image forming points 190 and 210, and the wafer surface 2 as the surface to be inspected coincides with the plane 200 on which the image forming points 190 and 210 exist. ing.

The state of FIG. 10 shows an image-forming state in which the lens system 11 changes the projection magnification so as to correspond to the state of FIG. 3 (B). The reason for changing the projection magnification of the lens system 11 is as follows.

When the lens system 11 remains at the same projection magnification as in the state of FIG. 9, when the position of the measurement point is moved by the light irradiation means SA, the luminous flux on the emitting side (position detecting element 17 side) The distance between the light beam 73a and the light beams 71a, 72a, 74a, 75a changes, and the light beams 71a, 72a, 74a,
75a does not enter the correction optical systems 12, 13, 15, and 16 (only the light beams 71a and 73a are shown).

Each luminous flux 71a, 72a, 74a, 75
Moving the correction optical systems 12, 13, 15, 16 in the plane perpendicular to the optical axis in accordance with the position of the lens system 11 in the plane perpendicular to the optical axis has a small spatial margin, There may be cases where they interfere with each other. Therefore, similarly to the lens system 8, the lens system 11 changes the projection magnification while keeping the both-side telecentric state, and the correction optical system 1
Correction is made for changes in the respective object point positions for 2, 13, 15, and 16.

Since the lens system 8 of the lens system 11 is telecentric on the exit side (wafer 2 side), it naturally becomes the telecentric on the entrance side (wafer 2 side).

Further, by making the lens system 11 telecentric on the exit side (position detecting element 17 side), changes in the positions of the image forming points 24 to 28 when the projection magnification is changed are corrected in parallel with each other. It is made to occur only in the optical axis direction of the optical systems 12 to 16 to facilitate the creation of a mechanical moving mechanism and prevent the correction optical systems 120 to 160 from interfering with each other when they are moved.

In FIG. 10, the luminous flux 73a corresponding to the measuring point 21 which is telecentric on both sides and the other measuring point 1
Light fluxes 71a, 72a corresponding to 9, 20, 22, 23,
The distances of 74a and 75a on the emitting side (position detecting element 17 side) are D ₁₁ (24), D ₁₁ (25), D ₁₁ (27), and D ₁₁ (28) (D ₁₁ (24) and D ₁₁ (24)). ₁₁ (19) only shown).

Further, the image forming magnifications when the measuring points 19 to 23 are imaged on the image forming points 24 to 28 by the lens system 11 are β ′ ₁₁ (19) to β ′ ₁₁ (23), respectively.

For the distance between the light beams, D ₁₁ (24) / D ₁₁ (19) = D ₁₁ (25) / D ₁₁ (20) = D ₁₁ (27) / D ₁₁ (22) = D ₁₁ ( _{28) / D 11 (23)} = β '11 relationship holds in (21).

The lens system 11 maintains a telecentric state on both the incident side and the emitting side, and β ′ ₁₁ (21) = β ₁₁ (21) × {β ′ ₈ (730) / β ₈ (730)} ⁻¹ The positions of the lenses 111 to 114 and the stopper diaphragm 41 are moved in the optical axis direction so that the above relationship holds.

Then, in the state of FIGS. 4 and 9, D ₁₁ (24) = D ₁₁ (19) × β ₁₁ (21) = D ₈ (19) × β ₁₁ (21) = D ₈ (710) × β ₈ (730) × β ₁₁ (21).

Even in the states of FIGS. 6 and 10, D ₁₁ (24) = D ′ ₁₁ (19) × β ′ ₁₁ (21) = D ′ ₈ (19) × β ′ ₁₁ (21) = {D ₈ ( _{710) × β '8 (730} )} × β' 11 (21) = {D 8 (710) × β '8 (730)} × [β 11 (21) × {β' 8 (730) / β 8 (730)} ⁻¹ ] = D ₈ (710) × β ₈ (730) × β ₁₁ (21), and keep D ₁₁ (24) constant regardless of the change in the positions of measurement points 19 to 23. (D ₁₁ (25), D ₁₁ (27), D ₁₁ (2
The same applies to 8). ).

Next, the correction optical system 1 in the state of FIG.
The adjustment of the positions of 2, 13, 15, 16 will be described.

The plane 20 on which the imaging points 190 and 210 exist
0 and a plane 1250 in which the image forming points 24 and 26 exist so as to share the same line of intersection with the plane 1100 in which the stopper diaphragm 41 in the lens system 11 exists (the plane in the figure). Reference numeral 1200 is a plane where the image formation points 24 and 26 in FIG. 9 exist.) In this state, the image is defocused on the position detecting element 17 at the remaining image forming points 24, 25, 27 and 28 excluding the image forming point 26 (only the image forming point 24 is shown).

In this embodiment, the images of all the image forming points 24 to 28 are formed on the position detecting element 17. Therefore, in the state of FIG. 12, the correction optical system 1 is applied to the image formation points 24 to 28.
2 to 16 image points 29 to 3 on the position detecting element 17
Each three of imaging magnification and _{β '12 (24) ~β'} 16 (28). The correction optical systems 12, 13, 15, and the correction optical systems 12 and 13 are controlled by the second variable mechanism so that the combined magnifications become equal to each other, β ′ (SBC).
16 is changed in the optical axis direction.

[0081] That is, β '(SBC) = β ' 11 (19) × β '12 (24) = β' 11 (20) × β '13 (25) = β' 11 (21) × β '14 ( and the _{26) = β '11 (22} ) × β' 15 (27) = β as established the relationship _{'11 (23) × β'} 16 (28).

When the measurement points 19 to 23 are arranged at the magnification shown in FIG. 3B, the lens system 11 and the correction optical systems 12 to 16 are arranged as shown in FIG. 12 in the light irradiation means SBC. The images of the pinholes 71 to 75 of the slit member 7 are
Measurement points 19 to 23 on the wafer 2, which is the surface to be inspected, and FIG.
Images are formed at points 24 to 28 on the plane 1250 of 0 and incident points 29 to 33 on the position detection element 17.

In the above embodiment, the mechanism for changing the mutual positions of a plurality of measuring points has been described.
When the arrangement of 3 is the magnification shown in FIG.
The composite magnification β (SA) in A, the composite magnification β (SBC) in the detection means SBC, and the arrangement of the measurement points 19 to 23 are shown in FIG.
In the case of the magnification shown in (B), the combined magnification β '(SA) in the light irradiation means SA and the combined magnification β' (SB in the detection means SBC.
Between C), β (SA) ≠ β ′ (SA) and β (SBC) ≠ β ′
The relationship of (SBC) is established.

In the above-mentioned embodiment, the measurement point 19
3 to 23 have the magnification shown in FIG. 3 (A), the combined magnification β (SA) in the light irradiation means SA, the combined magnification β (SBC) in the detection means SBC, and the arrangement of the measurement points 19 to 23. In the case of the magnification shown in FIG. 3B, the combined magnification β ′ (SA) in the light irradiation means SA and the combined magnification β ′ (S in the detection means SBC.
The relationship with BC) may be as follows.

When the arrangement of the measurement points 19 to 23 is the magnification shown in FIG. 3B, the correction optical system 140 corresponding to the measurement point 21 in the light irradiation means SA is replaced with the other correction optical systems 120 and 13.
Like 0, 150, 160, it has a structure movable in the optical axis direction, β ′ (SA) = β ′ ₁₂₀ (71) × β ′ ₈ (710) = β ′ ₁₃₀ (72) × β ′ ₈ (720 _{) = β '140 (73)} × β' 8 (730) = β '150 (74) × β' 8 (740) = β '160 (75) × β' 8 (750) = β relationship (SA) The correction optical systems 120 to 160 may be changed in the optical axis direction so that According to this, measurement point 1
Even if the arrangements of 9 to 23 are changed, the size of each measurement point can always be kept constant.

The arrangement of the measuring points 19 to 23 is shown in FIG.
In the case of the magnification shown in, the correction optical system 14 corresponding to the measurement point 21 in the detection means SBC is replaced with the other correction optical systems 12, 13,
15 and 16 and the movable structure in the optical axis direction as well, β '(SBC) = β ' 11 (19) × β '12 (24) = β' 11 (20) × β '13 (25) = _{β '11 (21) × β} ' 14 (26) = β '11 (22) × β' 15 (27) = β '11 (23) × β' 16 (28) = β relationship holds for (SBC) As described above, the correction optical systems 12 to 16 may be changed in the optical axis direction. According to this, the measurement points 19-
Even if the arrangement of 23 is changed, the detection magnification and the detection accuracy of each measurement point can always be kept constant.

The arrangement of the measurement points 19 to 23 is shown in FIG.
In the case of the magnification shown in, the correction optical system 140 corresponding to the measurement point 21 in the light irradiation means SA is replaced with another correction optical system 120,
Similar to 130, 150 and 160, the structure is such that it can move in the optical axis direction, and at the same time, the measuring point 21 in the detecting means SBC.
The correction optical system 14 corresponding to
As movable structure in the optical axis direction in the same manner as 3,15,16, β '(SA) = β' 120 (71) × β '8 (710) = β' 130 (72) × β '8 (720 _{) = β '140 (73)} × β' 8 (730) = β '150 (74) × β' 8 (740) = β '160 (75) × β' 8 (750) = β (SA) and, β '(SBC) = β' 11 (19) × β '12 (24) = β' 11 (20) × β '13 (25) = β' 11 (21) × β '14 (26) = β' _{11 (22) × β '15} (27) = β' 11 (23) × β '16 (28) = β so that the relationship is satisfied in (SBC), the correction optical system 120 to 160,
Also, the correction optical systems 12 to 16 may be changed in the optical axis direction.

According to this, even if the arrangement of the measuring points 19 to 23 is changed, the size of each measuring point can be always kept constant, and the detection magnification and the detection accuracy of each measuring point can be improved. Can also be kept constant.

[0089]

As described above, according to the present invention, the height information (surface position information) of a plurality of points in the exposure area on the wafer surface is exposed while taking into consideration the space restrictions for providing the correction optical system. By changing the relative positions of a plurality of measurement points while maintaining a similar shape in accordance with the size of the area, even if the wafer surface has an uneven shape or is tilted, A surface position detecting apparatus and a semiconductor element manufacturing method using the same, which can easily position the entire exposure area of the device within the allowable depth of focus of the projection optical system and thereby manufacture high density semiconductor elements. Can be achieved.

[Brief description of drawings]

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

FIG. 2 is an enlarged explanatory view of a part of FIG.

FIG. 3 is an enlarged explanatory view of a part of FIG.

FIG. 4 is an explanatory view of the vicinity of the first lens system in FIG.

5 is an explanatory view of the vicinity of the first lens system in FIG.

6 is an explanatory diagram of the vicinity of the first lens system in FIG.

FIG. 7 is an explanatory diagram of the vicinity of the first correction system in FIG.

FIG. 8 is an explanatory diagram of the vicinity of the first correction system in FIG.

9 is an explanatory view of the vicinity of the second lens system in FIG.

10 is an explanatory view of the vicinity of the second lens system in FIG.

11 is an explanatory diagram of the vicinity of the second correction system in FIG.

12 is an explanatory diagram of the vicinity of the second correction system in FIG.

[Explanation of symbols]

 SA light irradiation means SB projection means SC photoelectric conversion means 1 projection lens 1a reticle 2 wafer 3 wafer stage 4 stage control device 5 light source 6 collimator lens 7 slit member 8 lens system 9,10 mirror 11 light receiving lens 12-16 second correction System 17 Detection surface 18 Focus control device 71 to 75 Pinhole 120, 130, 140, 150, 160 First correction system

Claims (6)

[Claims] 1. A light irradiation means for irradiating a plurality of light beams to a plurality of positions on a surface to be inspected from an oblique direction, and a plurality of light beams reflected by the surface to be inspected are incident on a light receiving element surface, and onto the light receiving element surface. A surface position detecting device for detecting incident position information of the plurality of light beams to obtain surface position information of the surface to be detected, wherein the light irradiating means is provided on the surface to be detected of the plurality of light beams. It has a first variable mechanism that changes the incident position on
The surface position detection device, wherein the detection means has a second variable mechanism that relatively changes the incident positions of the plurality of light beams on the light receiving element surface. 2. The second variable mechanism keeps the incident positions of the plurality of light beams on the light receiving element surface constant even if the incident positions of the plurality of light beams on the surface to be inspected change in a similar manner. The surface position detecting device according to claim 1, wherein 3. The first variable mechanism has a bilateral telecentric first lens system and a plurality of first correction systems provided for each of the plurality of light beams, and the first lens system and the plurality of first correction systems. At least a part of the system is movable in the optical axis direction, and the second variable mechanism is a two-sided telecentric second system.
A lens system and a plurality of second correction systems provided for each of the plurality of light beams are provided, and at least a part of the second lens system and the plurality of second correction systems is movable in the optical axis direction. The surface position detecting device according to claim 1, wherein 4. When manufacturing a semiconductor device through a process of projecting and exposing a circuit pattern of a reticle onto a wafer surface by a projection optical system, a plurality of light beams are obliquely applied to a plurality of positions in a shot area on the wafer surface. A first variable mechanism for making incident positions similar to each other and making them incident, and a second variable mechanism for making a plurality of light beams reflected by the shot area of the wafer surface incident on the light receiving element while making incident positions similarly variable, The incident position information of the plurality of light beams on the light receiving element surface is detected to obtain the surface position information of the shot area of the wafer surface, and the shot area is moved to the image surface of the projection optical system based on the surface position information. A method of manufacturing a semiconductor device, comprising: projecting and exposing a circuit pattern of the reticle onto a shot area on the wafer surface by the projection optical system after positioning the reticle. 5. The second variable mechanism is configured to make the incident positions of the plurality of light beams on the light receiving element surface constant even if the incident positions of the plurality of light beams on the wafer surface are changed. The method for manufacturing a semiconductor device according to claim 4, wherein 6. The first variable mechanism has a bilateral telecentric first lens system and a plurality of first correction systems provided for each of the plurality of light beams, and the first lens system and the plurality of first correction systems. At least a part of the system is movable in the optical axis direction, and the second variable mechanism is a two-sided telecentric second system.
A lens system and a plurality of second correction systems provided for each of the plurality of light beams are provided, and at least a part of the second lens system and the plurality of second correction systems is movable in the optical axis direction. 5. The method for manufacturing a semiconductor device according to claim 4, wherein