JP3304535B2 - Surface position detection method and projection exposure apparatus using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a surface position and a projection exposure apparatus using the same. More particularly, in the manufacture of semiconductor devices, an electronic circuit pattern formed on a reticle surface is projected onto a wafer surface by a projection optical system. When reducing projection to
By detecting surface position information (height information) of a plurality of points on the wafer surface, the exposure area of the wafer can be easily positioned on the best image forming plane of the projection optical system, and a good projected image can be obtained. The present invention relates to a surface position detection method and a projection exposure apparatus using the same.

[0002]

2. Description of the Related Art In recent years, a projection exposure apparatus for manufacturing a semiconductor device has been required to have a fine electronic circuit pattern, for example, a submicron to a half micron and high integration. Accordingly, a projection optical system having higher resolution than before is required. For this reason, for example, in a projection optical system, the NA is increased and the exposure wavelength is shortened.

In general, if the NA is increased to increase the resolution of the projection optical system, the allowable depth of focus of pattern projection becomes smaller. For this reason, many projection exposure apparatuses use a surface position detection device that detects a focal plane position of a projection optical system. The surface position detecting device not only detects and adjusts the height position (surface position) information of the exposure area on the wafer surface on which the pattern is to be transferred, but also tilts the exposure area on the wafer surface on which the pattern is to be transferred. And the like can be simultaneously detected and adjusted.

Conventionally, as an apparatus for detecting the surface position of the focal plane, a plurality of air sensors are provided around the exposure area on the wafer surface, and the exposure area is obtained from height information on the periphery of the exposure area obtained from the air sensor. There is known a method of calculating and adjusting the inclination, height position and the like.

In Japanese Patent Publication No. 2-10361, the height position of the central portion of the exposure area on the wafer surface is detected and adjusted by an oblique incidence type height position detecting optical system. The tilt in the exposure area is calculated and adjusted using a tilt detection optical system (collimator).

In Japanese Patent Application No. 3-157822, the present applicant forms a plurality of measurement points in an exposure area in an oblique incidence type projection optical system, and calculates and adjusts the inclination and height position of the exposure area. A proposed surface position detecting device is proposed.

Further, the applicant of the present invention has disclosed in Japanese Patent Application Laid-Open No. 2-102518 a height position detecting optical system for measuring a plurality of points in an exposure area on a wafer. A surface position detecting device that calculates and adjusts the inclination and height position of the surface has been proposed.

[0008]

In general, in an optical detection system, the influence of interference generated between light reflected on the surface of a resist applied on a wafer and light reflected on the surface of a wafer substrate. Is a problem. The effect of this interference is
In the above-described conventional example, the pattern-specific offset is measured in advance at each of a plurality of measurement points, and the measured values at the plurality of points are corrected at the time of each shot exposure. Measurement is being performed.

[0009]

[0010]

[0011]

[0012]

[0013]

[0014]

[0015]

[0016]

However, in the peripheral portion of the wafer, some of the plurality of measurement points may be located in a wafer region where no pattern has been subjected to the offset measurement. In such a case, it has been necessary to measure the surface position of the wafer using a plurality of remaining measurement points excluding the measurement points located in the wafer region having no pattern. Therefore, in the peripheral portion of the wafer, the number of measurement points decreases, and the correction accuracy of the surface position tends to deteriorate.

An object of the present invention is to form a plurality of surface position detection mechanisms in an exposure area on a wafer, to enable correction of the same surface position at the peripheral portion of the wafer as at the central portion, and to realize a pattern with high resolution. An object of the present invention is to provide a surface position detecting method which can be easily obtained and a projection exposure apparatus using the same.

[0019]

[0020]

According to the surface position detecting method of the present invention, the projection optical system includes a plurality of pattern areas on a second object on which a pattern on a first object is projected via a projection optical system. Detecting the surface position in the optical axis direction of the system, measuring the surface position in the optical axis direction at a plurality of measurement points, and correcting the measurement value at each measurement point with a correction value for each measurement point; In the detection method, a plurality of correction values are set for a predetermined measurement point among the plurality of measurement points, and the correction value is selected from among the plurality according to a position of the pattern area on the second object. Is selected. Also, the projection exposure apparatus of the present invention is a projection exposure apparatus that projects a pattern on a reticle onto a plurality of pattern areas on a wafer via a projection optical system, wherein each of the plurality of pattern areas has an optical axis direction. Surface position detecting means for detecting a surface position with respect to, the surface position detecting means measures the surface position in the optical axis direction of the projection optical system at a plurality of measurement points for each of the pattern areas, at each measurement point Means for correcting the measurement value with a correction value for each measurement point, the correction value for a predetermined measurement point of the plurality of measurement points, according to the position of each pattern region on the wafer It is characterized by having a function of selecting from a plurality of correction values for a predetermined measurement point.

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

FIG. 1 is a schematic view of an essential part of an embodiment of a projection exposure apparatus with a surface position detecting device, and FIG. 2 is an enlarged explanatory view of a part of FIG.

In FIG. 1, reference numeral 1 denotes a reduction projection optical system (projection lens system), and Ax denotes an optical axis of the projection optical system 1. 1a
Is a reticle on which a circuit pattern is formed, and is mounted on a reticle stage 1b. 1
An illumination system c uniformly illuminates the surface of the reticle 1a. The projection optical system 1 reduces and projects the circuit pattern on the reticle 1a surface onto the wafer 2 surface. The wafer 2 is fixed on the wafer stage 3 by suction. 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. The tilt can be adjusted with respect to a plane (xy plane) orthogonal to Ax. Thereby, the surface position of the wafer 2 placed on the surface of the wafer stage 3 can be arbitrarily adjusted. Reference numeral 4 denotes a stage control device, which controls driving of the wafer stage 3 based on a signal from a focus control device 18 described later.

SA is light irradiation means, SB is projection means, SC
Denotes photoelectric conversion means, which constitute a part of a surface position detecting device for detecting surface position information of the wafer 2 surface.
The projection means SB and the photoelectric conversion means SC use the detection means SB.
C.

In this embodiment, a circuit pattern on the reticle 1a surface is projected onto the wafer 2 by the projection optical system 1 using a surface position detecting device.
When projecting on the surface, the drive of the wafer stage 3 is controlled so that the exposure area on the surface of the wafer 2 is located within the allowable depth of focus of the projection optical system 1. Then, move the wafer stage 3 to X
The rectangular pattern area (shot) 39 is sequentially formed on the surface of the wafer 2 by sequentially moving on the −Y plane.

Next, each element of the surface position detecting device of this embodiment will be described. First, the light irradiating 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 comprises 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 a light beam from the light source 5 as a parallel light beam having a substantially uniform cross-sectional intensity distribution. Numeral 7 denotes a prism-shaped slit member, in which a pair of prisms are bonded so that their inclined surfaces are opposed to each other, and a plurality of openings (five pinholes) 71 to 75 are formed on this bonded surface by shielding light such as chrome. It is provided using a film.

FIG. 3 is a schematic diagram when the slit member 7 is viewed from the collimator lens 6 side. As shown in FIG. 3, a plurality of (four) pinholes 711 are provided.
~ 714. Other pinholes 72, 73,
74 also has a plurality of (four) minute pinholes 721-7.
24, 731-734, 741-744.

Reference numeral 8 denotes a lens system, which is composed of both telecentric systems and has a plurality of pinholes 71 to 7 of the slit member 7.
The five independent light beams 71a to 75a passing through 5 are guided to five measurement points 19 to 23 on the surface of the wafer 2 via the mirror 9.

At this time, with respect to the lens system 8, the plane on which the pinholes 71 to 75 are formed and the plane including the surface of the wafer 2 meet the conditions of Scheimpflug's
condition). Here, assuming that the imaging magnification of the pinholes _{71 to 75} by the lens system 8 is β _{8 (71)} to β _{8 (75)} , β _{8 (71)} <β _{8 (72} ) <β
_{8 (73)} <β _{8 (74)} <β _{8 (75)} , and the pinhole closer to the lens system 8 has a larger imaging magnification.

In this embodiment, the fine pinhole 7
11 to 714, 721 to 724, 731 to 732, 74
Since 1 to 744, 751 to 754 are very close to each other, almost the same imaging magnification β _{8 (71)} , β _{8 (72)} ,
β _{8 (73)} , β _{8 (74)} , and β _{8 (75)} .

In this embodiment, minute pinholes 711 to 714, 721 to 724, 731 to 73 are formed on the surface of the wafer 2.
4,741 to 744,751 to 754 so that the respective images are projected to almost the same size.
~ 714, 721-724, 731-734, 741-
The diameters D of 744, 751 to 754 are respectively expressed by D ₇₁ = D
_{711 to} D ₇₁₄ , D ₇₂ = D _{721 to} D ₇₂₄ , D ₇₃ = D ₇₃₁ to
_{D 734, D 74 = D 741} ~D 744, when the D ₇₅ = D ₇₅₁ ~D ₇₅₄ so as to satisfy the following relationship is set to diameter D ₇₁ to D _75.

D ₇₁ : D ₇₂ : D ₇₃ : D ₇₄ : D ₇₅ = β _{8 (75)} : β _{8 (74)} : β _{8 (73)} : β _{8 (72)} : β _{8 (71)} The lens system 8 includes N of each light flux 71a to 75a inside.
An aperture stop 40 for aligning A is provided.

The light beams 71a, 72a, 73a, 74
a, 75a are measurement points 19, 20, and
21, 22, 23 are formed.

Each measurement point 19, 20,.
As shown in FIG. 4, minute pinholes 711-714, 721-724, 731-734, 7
Images 41 to 744, 751 to 754 are projected.
In the present embodiment, the light irradiating means SA is constituted by the above-described elements 5, 6, 7, 8, and 9.

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

The five light beams 71a to 75a incident on the surface of the wafer 2 are perpendicular to the wafer 2 (the direction of the optical axis Ax).
As shown in FIG. 2, the wafer 2 was rotated from the X direction (shot arrangement direction) by θ ° (for example, θ = 22.5 °) in the XY plane so as to be observed independently from each other as shown in FIG. It is incident from the direction.

As a result, the present applicant has filed Japanese Patent Application No. Hei 3-1578.
As proposed in Japanese Patent No. 22, the spatial arrangement of each element is made appropriate, and highly accurate detection of surface position information is facilitated.

In this embodiment, each of the above elements 5, 6, 7,
A plurality of light beams (pinholes) are made incident on the surface of the wafer 2 by the light irradiating means SA composed of 8 and 9. In this embodiment, the number of measurement points on the surface of the wafer 2 is not limited to five but may be any number.

Next, a plurality of reflected light beams from the wafer 2
The projection unit SB that guides light onto the detection surface 17 of the photoelectric conversion unit SC as a position detection element made of a CD and forms an image will be described.

Numeral 11 denotes a light receiving lens, which is composed of both telecentric systems and reflects five reflected light beams from the surface of the wafer 2 via the mirror 10. And the light receiving lens 11
Form a pinhole image at each position 24-28 with respect to each measurement point 19-23.

Reference numeral 41 denotes a stopper aperture provided on the light receiving lens 11, which is provided in common for each of the measurement points 19 to 23. High-order diffracted light, which is noise light generated when reflected, is cut. Each position 24
The light beams from the pinhole images of Nos. To 28 enter five correction optical systems 12 to 16 provided independently.

Since the light receiving lens 11 of the correction optical systems 12 to 16 is a bi-telecentric system, the optical axes thereof 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. Re-imaging is performed on the surface 17 so that spot lights having the same size are formed. The photoelectric conversion means SC comprises a single two-dimensional CCD. In the present embodiment, the projection means SB is constituted by the above elements 10, 11, 12 to 16.

Each of the correction optical systems 12 to 16 has a plane-parallel plate having a predetermined thickness and a lens system.
It is coaxial or eccentric with respect to one optical axis. At this time, the parallel plane plate is used to correct the optical path length of each lens system. The lens system has a detection surface 17 at each of the measurement points 19 to 23.
It is provided to correct the above imaging magnification (projection magnification) so as to be substantially equal.

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, a plurality of measurement points 19 to 23 having different distances from the light receiving lens 11 are connected to the photoelectric conversion means SC. When an image is formed on the detection surface 17, the imaging magnifications thereof are different from each other.

Therefore, in this embodiment, correction optical systems 12 to 16 are provided for each measurement point, and these measurement points 19 to 2 are provided.
The projection magnification on the detection surface 17 is set to be substantially equal (this correction optical system is described in detail in Japanese Patent Application No. 2-44236, filed by the present applicant).

At this time, each measurement point 19 on the wafer 2 surface
The position of the pinhole image (spot light) incident on the detection surface 17 is changed depending on the surface positions (height direction, optical axis Ax direction) of No. to No. 23. The photoelectric conversion means SC detects a change in the position of the pinhole image at this time. Thus, in this embodiment, the surface position information of each of the measurement points 19 to 23 on the surface of the wafer 2 can be detected with the same accuracy.

The measurement points 19 to 23 on the surface of the wafer 2 and the detection surface 17 of the photoelectric conversion means SC are set to be conjugate to each other via the projection means SB (with respect to each of the measurement points 19 to 23). (Correcting the fall). 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
The position of the pinhole image on the detection surface 17 changes in response to a local change in 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 unit 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 of the measurement points 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 of each measurement point 19 to 23 from C (surface position information)
From this, position information on the surface of the wafer 2, that is, a position in the optical axis Ax direction (z direction), an inclination with respect to the XY plane, and the like are obtained.

Then, a signal relating to the driving amount of the wafer stage 3 is input to the stage controller 4 so that the surface of the wafer 2 is substantially coincident with the projection surface of the reticle 1a by the projection optical system 1. The stage control device 4 drives and controls the wafer stage 3 in accordance with an input signal from the focus control means 18 to adjust the position and orientation of the wafer 2.

In this embodiment, regarding the light receiving lens system 11,
The surface including the measurement points 19 to 23 and the positions 24 to 28 on the surface of the wafer 2 is defined by the Scheimpflug's condition.
condition). here,
Assuming that the imaging magnifications β _{11 (19) to} β _{11 (23)} of the respective pinhole images on the measurement points 19 to 23 by the light receiving lens system 11, β
_{11 (19)} <β11 ₍₂₀₎ <β11 ₍₂₁₎ <β11 ₍₂₂₎ <β11 ₍₂₃₎ , and the pinhole closer to the light receiving lens system 11 has a larger imaging magnification.

On the other hand, each correction optical system 12, 1
Positions 24, 25, 26, 2 according to 3, 14, 15, 16
The imaging magnification of each of the pinhole images formed at the positions 7 and 28 with respect to the incident positions 29, 30, 31, 32 and 33 is β
_{Assuming that 12 (24)} , β _{13 (25)} , β _{14 (26)} , β _{15 (27)} , β _{16 (28)} , the pinhole images on the measurement points 19, 20, 21, 22, ₂₃ are Incident positions 29, 30, 31, 32, 33
, The imaging magnifications are set to β _{12 (24)} , β _{13 (25)} , β _{14 (26)} , β _{15 (27)} , β such that the following equation holds.
_{16 (28)} is stipulated.

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) In} this embodiment, as disclosed in the above-mentioned Japanese Patent Application No. 3-157822, the correction optical systems 12 to 16 are used in the oblique incidence type projection optical system. A plurality of measurement points are selected so that the resolution and accuracy of height detection at each measurement point are substantially equal.

Next, before describing the features of the present embodiment, a case of measuring the topography in a test area on a wafer surface with a conventional surface position detecting apparatus will be described.

FIG. 20 shows that the present applicant disclosed in Japanese Patent Laid-Open No. 2-19813.
In the surface position detecting device proposed in Japanese Patent Application Publication No. 0-204, a beam having a constant beam diameter and a uniform intensity distribution within the beam diameter is formed on a wafer having a pattern 52 formed on a substrate 51 on which a resist 53 is applied and formed in a previous process. A schematic diagram showing a state in which a light beam 54 having a light beam is incident and reflected by the surface of the resist 53, the pattern 52, and the surface of the substrate 51, thereby forming a reflected light beam 540 having a different intensity distribution within the beam diameter. It is.

At this time, the step of the pattern 52 is small and the surface of the resist 53 is flat because the resist 53 is applied sufficiently thick.

FIG. 21 shows a resist 53 and a pattern 52.
Light beam 540 reflected and formed on the surface of the substrate 51
Is an intensity distribution 5 in a state where an image is formed on a light receiving element (not shown).
FIG.

In FIG. 20, a light beam 54 having a constant beam diameter and a uniform intensity distribution within the beam diameter is applied to a resist 53.
Is obliquely incident on the wafer on which is coated. At this time, the light beam 54 has a component 55 reflected on the surface of the resist 53.
0 and 560, and components 55 that pass through the resist 53 and reflect off the surface of the substrate 51 and then exit the resist 53 again.
After passing through the resist 53 and being reflected on the surface of the pattern 52, it is separated into a component 561 that goes out of the resist 53 again.

As described above, the reflected light beam 54 reflected by the wafer
0 is a combination of a component 550 reflected on the surface of the resist 53 and a component 551 reflected on the surface of the substrate 51, and a component 560 reflected on the surface of the resist 53 and a component reflected on the surface of the pattern 52. 561 are synthesized.

Therefore, in FIG. 20, the component 560 reflected on the surface of the resist 53 and the pattern 5
The reflectivity of the light flux obtained by combining the component 561 reflected on the surface of the resist 53 with the component 561 reflected on the surface of the resist 53 is better.
Assuming that the component 50 and the component 551 reflected on the surface of the substrate 51 are higher than the reflectance of the combined light beam (there may be the opposite depending on the interference condition of the thin film), as shown in FIG. A reflected light flux 540 indicating the intensity distribution 57 is formed.

As described above, the intensity distribution within the beam diameter of the reflected light beam changes depending on the position of the pattern arranged within the beam diameter of the incident light beam. Further, even if the position of the pattern arranged within the beam diameter of the incident light beam is the same, the intensity distribution within the beam diameter of the reflected light beam changes when the resist thickness changes and the interference condition of the thin film changes.

Then, when the center of gravity of the intensity distribution within the beam diameter of the reflected light beam formed on the light receiving element is detected and measured as the position of incidence of the reflected light beam on the light receiving element, the relative position between the pattern 52 and the incident light beam is measured. Due to the change in the position and the thickness of the resist, the center of gravity 58 of the intensity of the reflected light beam changes while the wafer is at the same position in the optical axis direction AX of the projection lens, and the measured value is the relative position between the pattern 52 and the incident light beam and the thickness of the resist. Will have a detection error corresponding to.

That is, as shown in FIG.
When the step of 2 is small and the resist 53 is applied sufficiently thick, the surface of the resist 53 is flat, and the center of gravity 58 of the intensity of the reflected light beam is detected even in the topographically equal region. When the method is used, a detection error may occur when measuring the topography of the wafer surface.

Therefore, in this embodiment, C is used as the position detecting means.
The image of the reflected light beam incident on the detection surface 17 is subjected to image processing using a CD sensor, thereby eliminating measurement errors due to the distortion of the reflected light beam image caused by optical factors (such as thin film interference by resist) on the wafer. The topography in the test area is accurately measured.

Next, the structural features of this embodiment will be described.

FIG. 5 is a schematic sectional view showing an optical path when a light beam enters the wafer 2 of FIG. In FIG.
Is applied to the pattern 52 formed in the previous process.
A plurality of (four) minute light beams 611, 612, 613, 6 having substantially the same intensity formed by a plurality of (four) minute pinholes of one pinhole on the wafer 2 provided thereon.
14 are incident, and the plurality (four) of the minute light beams 611 to 611
614 is the surface of the resist 53, the pattern 52 and the substrate 5
A plurality of minute reflected light beams 615, 616, 617, and 6 having different intensities by being reflected by the surface
18 illustrates a state in which the pixel 18 is formed.

At this time, the step of the pattern 52 is small, and the surface of the resist 53 is flat because the resist 53 is applied sufficiently thick.

FIG. 6 is a view showing the state of the intensity distribution when a plurality of minute reflected light beams 615 to 618 reflected and formed on the surface of the resist 53, the pattern 52 and the substrate 51 form an image on the detection surface 17. FIG.

In FIG. 5, a plurality of minute light beams 611, 61 having substantially the same intensity formed by the minute pinholes are shown.
2,613,614 are obliquely incident on the wafer on which the resist 53 is applied. At this time, the minute light beam 61
1, 612 are components 6 reflected on the surface of the resist 53;
50 and 660, and components 6 that pass through the resist 53 and reflect off the surface of the substrate 51, and then exit the resist 53 again.
51 and 661. Also, the minute light beams 613, 6
14 are components 670 and 680 that are reflected on the surface of the resist 53, and components 67 that are transmitted through the resist 53 and reflected on the surface of the pattern 52, and then exit the resist 53 again.
1,681.

As described above, the minute reflected light beams 615 and 616 reflected on the wafer 2 are composed of the components 650 and 660 reflected on the surface of the resist 53 and the components 651 and 661 reflected on the surface of the substrate 51, respectively. Is done. The minute reflected light beams 617 and 618 reflected by the wafer 2
670, 680 reflected on the surface of the pattern and the pattern 52
Are combined with components 671 and 681 reflected by the surface.

Therefore, the reflectance of the minute reflected light fluxes 617 and 618 reflected by the wafer 2 due to the interference of the thin film in FIG.
Assuming that the reflectance is higher than the reflectance of the minute reflected light beams 615 and 616 reflected by the wafer (there may be the opposite depending on the interference condition of the thin film), as shown in FIG.
In FIG. 8, a bias occurs between the intensities of the respective light beams.

At this time, considering the center of gravity 601 of the intensity of the plurality of minute reflected light beams 615 to 618 in which the intensity of each light beam is deviated on the detection surface 17 in FIG.
Similarly to the center of gravity 58 of the intensity distribution 57 of the reflected light beam 540 described in the above, the intensity of each of the plurality of minute reflected light beams 615 to 618 depends on the position of the pattern arranged at the reflection point of the plurality of minute light beams 611 to 614. Change. Further, even if the positions of the patterns arranged at the reflection points of the plurality of light beams 611 to 614 are the same, the intensity of each of the plurality of minute reflected light beams 615 to 618 changes when the resist thickness changes and the interference condition of the thin film changes. (Intensities of the light beams 615 and 616 and the light beams 617 and 618 occur).

Therefore, in this embodiment, a plurality of minute reflected light beams 615, 6
16,617,618 individual centers 605,606,6
07,608. Individual centers 605, 60
From 6,607,608, the average value of these centers is set as the center 600 of the whole. The overall center 600 always shows a constant value even if there is a deviation between the intensities of the light beams in the plurality of minute reflected light beams 615 to 618.

Next, in FIG. 5, one of the plurality of minute light beams 611 to 614 is reflected at the boundary between the substrate 51 and the pattern 52, and the intensity distribution of the minute reflected light beam 618 is distorted. Will be described.

FIG. 7 shows a plurality of minute reflected light beams 615 to 617 formed by reflecting on the surface of the resist 53 and the substrate 51.
FIG. 7 is an explanatory diagram showing a state in which a minute reflected light beam 618 formed by reflection at the boundary between the resist 53 and the substrate 51 and the pattern 52 forms an image on the detection surface 17.

In this case, a plurality of minute light beams 615 to 618
, The measurement error due to the distortion of the intensity distribution of the light beam 618 is reduced to ４ by the averaging effect.

Further, a plurality of minute reflected light beams 615 to 618
When the individual centers 605 to 608 are obtained, the method shown in Japanese Patent Application No. 4-108634 previously proposed by the present applicant can be used to perform measurement with extremely small errors even when there is distortion in the intensity distribution of the reflected light flux. And

That is, each minute reflected light flux 615-6
18, a method of setting a slice level of a fixed ratio and obtaining a center from an intersection between the slice level and both edges of the reflected light image, a method of similarly obtaining a center from an intersection of the slice level and one edge of the reflected light image, A method in which a fixed ratio of slice levels is set at two points, an upper limit and a lower limit, and the center is determined from each level and the area surrounded by the reflected light beam image. The reflected light beam image when the surface to be measured is an ideal mirror surface is stored in a memory. A method is used in which the center is determined by matching with a reflected light beam image having a distorted intensity distribution.

As described above, in the present embodiment, a CCD sensor is used as a position detecting element, and the image of the reflected light beam on the detection surface 17 is detected by image processing, and a plurality of minute light beams used for the detected light beam are appropriately numbered. In this case, the topography in the inspection area on the wafer is accurately measured.

Next, a method for measuring a plurality of points on the wafer 2, measuring the topography in the inspection area on the wafer 2, and reflecting the measured values on the measured values at the respective measurement points will be described.

FIG. 8 is an explanatory diagram showing a positional relationship between a predetermined pattern area 39 on the wafer 2 shown in FIG. 2, a plurality of measurement points 19 to 23, and a grid 80 for topography measurement in a test area. It is.

In the state shown in FIG. 8, the predetermined pattern area 39 of the wafer 2 is different from the pattern on the reticle 1a.
It is aligned with respect to the XY plane. In this embodiment, it is assumed that the grating 80 in the figure includes a plurality of measurement points 19 to 23 (they need not be included), and the height position is fixed in the direction of the optical axis Ax of the projection lens system 1 of the wafer 2. In this state, the wafer stage 3 is moved into the XY plane, and the measurement of the surface position is sequentially performed using the measurement points 21. At this time, the number of grid points for measuring the surface position of the pattern area 39 and the interval between the grid points are appropriately selected, and the topography in the pattern area 39 is accurately measured.

FIG. 9A is a schematic diagram showing the topography of the pattern region 39, and FIG.
FIG. 4 is a diagram showing a topography cross section at the position of the alternate long and short dash line shown in FIG.

In this embodiment, an offset value (correction amount) for detecting the surface position of each pattern area 39 on the wafer 2 is calculated using the plurality of surface position data.

FIG. 10 is a flowchart showing a method of calculating the offset value (correction amount). Hereinafter, a method of calculating the offset value will be described with reference to the flowchart in FIG. 10 and FIGS.

First, the wafer stage 3 is driven by the stage controller 4 and the wafer 2 is moved in the XY plane, so that the pattern on the reticle 1a has a predetermined pattern area 39 on the wafer 2 (for example, the wafer 3). The first shot above) is aligned.

Next, the surface position in the pattern area 39 on the wafer 2 at this position is determined by a plurality of measurement points 19, 20, 21, and
22 and 23, and these measured values are calculated as f ₁₉ , f ₂₀ and f
_21, and f _22, f _23. Next, the projection lens 1 of the wafer 2
With the optical axis AX direction of, that is, the height direction fixed,
The wafer 2 is sequentially moved in the XY plane so that each grid point (n) of the grid 80 in FIG. 8 coincides with the pinhole image formation position (incidence of minute plural light beams) at the measurement point 21.

The surface of the wafer 2 is measured at the measurement point 21 for each of these n grid points to obtain n measured values (surface position data). These n measured values Aj (j = 1 to n)
And

At this time, a plurality of measurement points 19, 20, 21,
The measurement values 22 and 23 are calibrated to the xy plane on which the stage 3 is driven so that the respective measurement values indicate the same measurement value.

That is, when there are lattice points that coincide with a plurality of measurement points 19, 20, 21, 22, 23 among the n lattice points, the measured values of the corresponding lattice points are represented by A _o , A _p , a _q, for a _r, carry shake I Deployment When a _s is not performed, f ₁₉ ≠ a _o, of _{f 20 ≠ a p, f 21} = a q, f 22 ≠ a r, f 23 ≠ a s Relationship (if calibrated, f
₁₉ = A _o , f ₂₀ = A _p , f ₂₁ = A _q , f ₂₂ = A _r , f ₂₃ = A
_s . ).

Here, C ₁₉ = f ₁₉ -A _o , C ₂₀ = f ₂₀ -A _p , C ₂₁ = f ₂₁ -A _q = 0 C ₂₂ = f ₂₂ -A _r , C ₂₃ = f ₂₃ -A _{As s} , the values obtained by correcting the measured values of the plurality of measurement points 19, 20, 21, 22, 23 as follows are new measured values F ₁₉ , F
_20, and _{F 21, F 22, F 23} .

That is, assuming that F ₁₉ = f ₁₉ -C ₁₉ F ₂₀ = f ₂₀ -C ₂₀ F ₂₁ = f ₂₁ F ₂₂ = f ₂₂ -C ₂₂ F ₂₃ = f ₂₃ -C ₂₃ Is calculated.

Further, a plurality of measurement points 1 out of n grid points
If there is no grid point that matches 9, 20, 21, 22, 23, a plurality of measurement points 19, 20, 21, 22, 22,
23 Measurement values A _{o (inter.)} , A at a plurality of measurement point positions obtained by interpolation from the measurement values of the neighboring grid points
_{p (inter.), A q} (inter.), A r (inter.), with A s _(inter.), in the same manner as described above, the new measured values F ₁₉ performs correction, F _20, F ₂₁ , F ₂₂ and F ₂₃ are obtained.

This calibration is adjusted in advance so that the plurality of measuring points 19, 20, 21, 22, 23 of the present embodiment show the same measured value with respect to the xy plane on which the stage 3 is driven. You do not need to do it.

At this time, the following topography offset correction is calculated with F ₁₉ = f ₁₉ F ₂₀ = f ₂₀ F ₂₁ = f ₂₁ F ₂₂ = f ₂₂ F ₂₃ = f ₂₃ . (Figure 10,11,14,15,16 in advance the carry a flow chart of the operation of the in shake I Deployment of made state.) Performs a least square plane approximation to the next measured n data A _j, this using a linear component of the wafer 2 on the pattern region 39, n data a _J and five data F ₁₉ to F ₂₃ tilt correction, newly n data a _'j and five data F to calculate the _'19 ~F' _23.

In the pattern area 39 shown in FIG.
Numeral 1 is a topographically convex portion having a memory portion and the like formed thereon, and a region 92 is a topographically concave portion having a scribe line, a bonding pad and the like formed thereon.

At this time, the maximum value A ′ _max and the minimum value A ′ _min of the n data A ′ _j are obtained in the direction shown by the topography section 93 in FIG. 9B, that is, in the height direction. average a _'center (data a' becomes the median value of _j) 9
5 is calculated, and slice levels 94 and 96 at fixed intervals are set around this value.

The slice levels 94, 9 at the fixed intervals
Assuming that the range between 5,96 is S _upper and S _lower ,
In the newly calculated n data A ′ _j , the range S _upper
A ′ _k and the data included in the range S _lower as A ′ ₁ (where k = 1 to h, 1 = 1 to i,
h + i = n), the average value A ' _{upper of} the h data A' _k and the average value A ' _lower of the i data A' ₁ are calculated.

For example, when a wiring pattern is transferred onto the convex area 91 in which the memory section is formed, the wiring pattern has a smaller depth of focus than a pattern transferred onto the concave area. Each of multiple measurement points 1
For the measured values of 9, _{20, 21, 22, and 23} , the offset value (correction amount) is set to F ₁₉ '-A' _upper F ₂₀ '-A' _upper F ₂₁ '-A' _upper F ₂₂ '-A' _upper set to F ₂₃ '-A' _upper, subtracting the measured value.

That is, F ₁₉ − (F ₁₉ ′ −A ′ _upper ) F ₂₀ − (F ₂₀ ′ −A ′ _upper ) F ₂₁ − (F ₂₁ ′ −A ′ _upper ) F ₂₂ − (F ₂₂ ′ −A performs control of the surface position of the pattern region 39 with a value of _{- 'upper) F 23 (F} 23' -A 'upper), to the pattern region 91 and the pattern area 92, performing pattern transfer simultaneously.

A plurality of measurement points 19 to 23 in each pattern area are used as offset amounts (correction amounts) when detecting the wafer surface position of the remaining pattern area on wafer 2.
(F ₁₉ ′ −A ′ _upper ) to (F ₂₃ ′ −)
A ′ _upper ) is subtracted, and the surface position of the convex region 91 can be detected topographically.

Similarly, when the bonding pad is transferred onto the concave region 92, the pattern of the bonding pad has a greater depth of focus than the pattern transferred onto the convex region 91 in this case. Since it is small, the offset value (correction amount) is set to F ₁₉ ′ −A ′ _lower F ₂₀ ′ −A ′ _lower F ₂₁ ′ −A ′ with respect to the measurement value of each of the plurality of measurement points 19, 20, 21, 22, ₂₃ provide that _{lower F 22 '-A' lower F} 23 '-A' lower.

The procedure described above is programmed in advance in the focus control device 18 in FIG. 1, and the value of the offset amount (correction amount) is of course
8 is stored in the memory.

As the value of the offset amount (correction amount), (F ₁₉ ′ -A ′ _upper ) to (F ₂₃ ′ -A ′ _upper ) or (F ₁₉ ′ -A ′ _lower ) to (F ₂₃ ′ -A ′) Whether to use _lower ) is previously specified in the program in each step.

Then, based on the surface position data of a plurality of measurement points in the pattern area on the wafer 2 obtained by the apparatus shown in FIG. 1 and the offset amount (correction amount), the pattern area (surface to be inspected) is determined. The surface position is detected, and the wafer 2 is moved in the direction of the optical axis AX so that the difference between this surface position and the known image plane position of the projection lens 1 becomes zero, and a plane (xy) perpendicular to the optical axis AX is set. Reticle 1
The pattern image on a is focused on the pattern area of the wafer 2.

At this time, the surface position of the pattern area (surface to be inspected) is defined as a least-square plane calculated from the surface position data of a plurality of measurement points in the pattern area.

Then, such an operation is sequentially performed for each pattern area on the wafer 2, and the reticle 1 is transferred to each area.
The pattern on a is projected and transferred.

The measurement for calculating the offset amount (correction amount) need not be performed for each wafer, but may be performed using at least one of a plurality of wafers processed in the same process. Therefore, the correction amount is calculated using a predetermined pattern area of the first wafer of one lot and stored in the memory, and when the second and subsequent wafer surface positions of the same lot are detected, the offset stored in the memory is used. The amount (correction amount) may be used.

Alternatively, it is sufficient to perform measurement for calculating the offset amount (correction amount) on the first wafer every time the reticle type is exchanged. In any case,
The impact on overall throughput is minimal.

FIG. 11 is a flowchart showing the exposure operation when the offset amount (correction amount) is calculated for each lot. The offset amount (correction amount) calculation step 110 in the figure is the same as that in FIG. It is executed in the sequence shown.

In this embodiment, each range S _upper ,
In the offset amount (correction amount) for S _lower , which value to use depending on the process is previously selected and instructed in a program for performing pattern exposure. It may be automatically selected and determined regardless of the type.

The first is that simply the range S _upper and the range S _lower
Of these, the offset amount (correction amount) having the larger number of included data is automatically selected.

Second, a least-squares plane of the data measured corresponding to the grid points is obtained, and the data after correcting the linear component thereof is defined as A ′ _j (j = 1 to n). S
A ' _k is included in _upper and A' ₁ is included in range S _lower (where k = 1 to h, 1 = 1 to i,
h + i = n), the average value A ' _{upper of} the h data A' _k and the average value A ' _lower of the i data A' ₁ are calculated.

At this time, each of the plurality of measurement points 19, 20,
For the measured values of 21, 22, 23, the offset value (correction amount) is represented by F ₁₉ ′ − (k × A ′ _upper + 1 × A ′ _lower ) / n F ₂₀ ′ − (k × A ′ _upper + 1 × A ′) _{lower) / n F 21 '-} (k × A' upper + 1 × A 'lower) / n F 22' - (k × A 'upper + 1 × A' lower) / n F 23 '- (k × A' upper + 1 × A ′ _lower ) / n is automatically determined.

Thus, the surface position is set at the position of the center of gravity of the occupied area ratio with emphasis on a portion occupying a larger area in the pattern region 39.

Third, a two-dimensional CCD sensor 120 is arranged on the stage 3 as shown in FIG. In this case, the stage 3 is moved in the XY plane, and the two-dimensional CCD sensor 120 is positioned directly below the projection lens 1. Next, the stage 3 is moved to the optical axis A of the projection lens 1.
Move in the X direction and within a plane perpendicular to the optical axis AX (xy
The reticle 1a is proved by the illumination system 1c, and a pattern image on the reticle 1a is formed on a two-dimensional CCD sensor 120 attached to the stage 3.
From the two-dimensional light intensity distribution of the pattern image on the two-dimensional CCD sensor 120, two-dimensional information on the position distribution of the pattern on the reticle 1a projected and transferred to the pattern area 39 is obtained.

The two-dimensional information of the pattern image is stored in the memory, and it is determined to which part of the pattern area 39 the pattern image is transferred. Then, it is determined which of the lattice points A ′ _j has the pattern image, and the topography (height of the optical axis AX) of the lattice point having the pattern image is determined in either the range S _upper or the range S _lower . , The offset amount (correction amount) is automatically selected (F ₁₉ ′ −A ′ _{upper to} F ₂₃ ′ −A ′ _upper or F ₁₉ ′).
−A ′ _{lower to} F ₂₃ ′ −A ′ _lower ).

When the two-dimensional distribution of the pattern image is located substantially in both the range S _upper and the range S _lower , the offset value (correction amount) is set to F ₁₉ ′ − (A ′ _upper + A ′). _{lower) / 2 F 20 '-} (A' upper + A 'lower) / 2 F 21' - (A 'upper + A' lower) / 2 F 22 '- (A' upper + A 'lower) / 2 F 23' - (A ' _upper + A' _lower ) / 2 and an average of both offset values (correction amounts) are used.

FIGS. 14 and 15 show flowcharts for automatically setting the offset amount (correction amount) in this case.

In the third case, a light receiving element 131 having a pinhole 132 may be provided on the stage 3 instead of the two-dimensional CCD sensor 120 as shown in FIG.

In this case, in the area where the pattern image on the reticle 1a is projected by the projection lens 1, the grating 1
The stage 3 is moved in the XY plane so that each of the 30 grid points coincides with the position of the light receiving element 131 having a pinhole,
The light amount passing through the pinhole 132 at each lattice point position is measured by the light receiving element 131.

At this time, the light receiving element 131 with the pinhole 132 is maintained at substantially the height of the image plane of the projection lens 1 in the optical axis AX direction.

Also, the diameter of the pinhole 132 is
Suppose that the pattern image is sufficiently larger than the pattern image of the reticle 1a projected on the reticle 32 (up to about 100 μm = a diameter similar to the scribe line), and the number of the gratings 130 is the same as that of the grating 80 for the topography measurement. Or grid 8
It is good to include 0.

In this case, from the light intensity distribution at each grid point,
Two-dimensional information on the position distribution of the pattern on the reticle 1a projected and transferred to the pattern area 39 can be obtained.
The information of the light intensity distribution of each lattice point is stored in the memory, and it is determined which part of the pattern area 39 the pattern image is transferred. The setting of the offset amount (correction amount) is the same as described above.

FIG. 16 is a flowchart for automatically setting the offset amount (correction amount) in this case.

In the examples shown in FIGS. 13, 14, and 15,
After storing the two-dimensional information of the pattern image in the memory and determining in which part of the pattern area 39 the pattern image is to be transferred, grid points for topography measurement may be set.

FIG. 17 is a flowchart for automatically setting the offset amount (correction amount) in this case.

In the above embodiment, the method of obtaining the offset amount (correction amount) for the relatively simple memory chip of the wafer surface topography has been described. However, as in the case of an ASIC in which the wafer surface topography is more complicated. For such a chip, the offset amount (correction amount) may be determined as follows.

FIG. 18A is a schematic diagram showing a topography of a pattern region 390 of a chip such as an ASIC, and FIG. 18B is a diagram of a two-dot chain line shown in FIG.
FIG. 18C is a diagram showing a topography cross section at the position indicated by the alternate long and short dash line shown in FIG. 18A.

In the pattern region 390 of FIG. 18A, regions 910, 911, 912, and 913 are topographically convex, but have different heights, and a region 920 is formed with scribe lines, bonding pads, and the like. It has a concave topographically. Again, the inclination of the corrected n data A _'j and five data F' ₁₉
Far to calculate the to F _'23 is as defined above.

[0137] At this time, FIG. 18 (B), (C) direction shown in topography section 930 and 931, i.e. in the height direction, 'maximum position A of the _j' n pieces of data A _max, the minimum value A ' seek _min, '(the median of _j these average a data a) _center' 950 is calculated and set the slice level 940 and 960 at constant intervals around this value.

Further, the slice level 94 at the fixed interval is used.
The range between 0, 950 and 960 is defined as S _upper , S _lower
And

FIG. 19A shows a predetermined pattern area 39 on the wafer 2 shown in FIG.
Grating 80 for topography measurement, and regions 190 and 20 separating grid points of grating 80 for topography measurement
It is a figure which shows the positional relationship of 0,210,220,230.

FIG. 19B shows an area 19 for dividing grid points.
It is a figure which shows only 0, 200, 210, 220, 230, and is divided into five areas corresponding to the number of a plurality of measurement points 19-23.

In the case of this embodiment, each of the plurality of measurement points 19 to
A different offset amount (correction amount) is set for each.

That is, n data A ' _190j , A'
_{200j, A '210j, A'} 220j, and A _{'230 j} (data at the boundary of the region is assumed to be included I dub in both areas.).

Among the data A ′ _190j included in the area 190, the average value A ′ _{190upper of} the data included in the range S _upper defined by the slice levels 940 and 950,
The average value of the data included in the range S _lower defined by the slice levels 950 and 960 is A ′ _{190 lower} .

Similarly, regions 200, 210, and 22
Data A _'200j, A' contained in 0,230 _210j, A '
_{Even for 220j} and A ' _230j , the average values A' _200upper , A ' _210upper and A' of the data included in the range S _{upper
220upper,} A _'230upper and scope mean value A of the data contained in _{S lower' 200lower, A '210lower} , A'
_220lower , A ' _{Calculate 230lower} (At this time, generally, A'
_190upper ≠ A ' _200upper ≠ A' _210upper ≠ A ' _220upper
≠ A ' _230upper , A' _190lower ≠ A ' _200lower ≠
_A'210lower ≠ _A'220lower ≠ _A'230lower . ).

When the offset value (correction amount) is reflected, for example, when a pattern having a smaller depth than the pattern transferred to the concave area 920 is transferred onto the convex areas 910, 911, 912, and 913, each of them is reflected. Multiple measurement points 19, 2
To the measured value of 0,21,22,23, the offset value (correction amount) _{F 19 '-A' 190upper F 20} '-A' 200upper F 21 '-A' 210upper F 22 '-A' 220upper F 23 '-A' Set to _{230 upper} and subtract from the measured value.

[0146] That _{is, F 19 - (F 19 '} -A' 190upper) F 20 - (F 20 '-A' 200upper) F 21 - (F 21 '-A' 210upper) F 22 - (F 22 '-A and controls the surface position of the pattern region 39 with a value of _{- '220upper) F 23 (F} 23' -A '230upper),
Transfer the pattern.

Similarly, when a pattern having a smaller depth of focus than a pattern transferred to another area is transferred onto the concave area 920, each of the plurality of measurement points 19, 20, and 2 is transferred.
To the measured value of 1,22,23, the offset value (correction _{amount) F 19 '-A' 190lower F} 20 '-A' 200lower F 21 '-A' 210lower F 22 '-A' 220lower F 23 '- A ' _230lower .

The procedure described above is programmed in advance in the focus control device 18 shown in FIG. 1, and the value of the offset amount (correction amount) is of course
That is stored in the 8 memory, as the value of the offset amount (correction _{amount), (F 19 '-A'} 190upper) ~ (F 23 '-A' 230upper) or _{(F 19 '-A' 190lower)} ~ ( F ₂₃ is either used _'-A' 230lower), is similar to the example also the aforementioned points are those indicated in advance in the program by each step. or,
Also in the case of this example, the offset amount (correction amount) may be automatically selected and determined as in the above-described example.

If the pattern area to be measured has a distortion such as a local warp, the obtained offset amount (correction amount) includes an error due to the distortion.

When it is desired to reduce such errors and increase the accuracy of the offset amount (correction amount), the above-described measurement and calculation are performed for a plurality of pattern areas on the wafer, and a plurality of correction amounts are calculated. The average value may be determined as an offset amount (correction amount) to be actually used, or a plurality of different wafers (of the same pattern structure processed in the same process) may be used. If the actual offset amount (correction amount) is obtained from the average value of the offset amount (correction amount), the accuracy of the offset amount (correction amount) is further improved.

In the above embodiment, the center measurement point 21 of a plurality of measurement points is used to measure n measurement values A _j (j = 1 to n) at each grid point on the pattern area. Was
Instead of the central measuring point 21, peripheral measuring points 19, 20,
Any one of the measurement points 21, 21, 23 may be used.

Further, the wafer is moved to each grid point on the pattern area in the above embodiment so that the center measurement point 21 among the plurality of measurement points coincides with each other, and all the plurality of measurement points at this time (or The average value A ′ _upper and the average value A ′ _lower may be calculated using 5 × n (or ４4 × n) data of some measurement points). In this case, the operation of moving to each grid point on the pattern area is performed once, and the data increases five times (or up to four times). Therefore, the measurement accuracy of the offset amount (correction amount) can be improved without lowering the throughput. There are benefits to improve.

In the above embodiment, n measured values A _j (j = 1 to n) of each grid point on the pattern area are used as the measured values for calculating the average value A ′ _upper and the average value A ′ _lower. )
Only average value A ' _upper , average value A'
_As measurement values for calculating _lower , n measurement values A _j (j = 1 to n) of each grid point on the pattern area and a plurality of measurement points 19, 20, 21, 22, and 22 in the pattern area 2
Alternatively, both of the measured values F ₁₉ , F ₂₀ , F ₂₁ , F ₂₂ , and F ₂₃ may be used.

In the above embodiment, the topography of the wafer surface is determined by the slice levels 94, 95, 96 at regular intervals.
The range between the and S _upper, S _lower binarization has been determined offset amount (correction amount), further increase the number of slice levels, for example, the offset amount range for obtaining the (correction amount) S _upper, Subdivided into S _middle and S _lower ,
The offset amount (correction amount) for measuring the surface position may be determined from the data included in each range.

Further, in the above-described embodiment, only the example in which the measurement of the surface position of each lattice point is performed while the wafer stage is once stopped with respect to the surface position measuring device is shown, but the measurement is continuously performed without stopping the wafer stage. The measurement may be repeated at a certain sampling interval while feeding, and the surface position of each grid point may be measured. At this time, the light source 5 and the position detecting element 17 are controlled to periodically issue the light source and synchronize the surface position data.

Further, the grid points for the measurement in the above embodiment are as follows:
The collection is not limited to a rectangular grid at regular intervals, and may be an aggregate of measurement points having different coordinates distributed in a two-dimensional plane.

In the above embodiment, some of the measured values of each grid point on the pattern area show values (anomalous values due to dust or the like) that are farther apart from other measured values than the topography of the wafer surface. If it occurs, it is advantageous not to use this measured value (abnormal value due to dust or the like) for calculating the offset amount (correction amount). Therefore, in such a case, the offset amount (correction amount) is calculated from the remaining measured values excluding this measured value (abnormal value due to dust or the like).

FIG. 22 is a schematic view of a main part of Embodiment 1 of the present invention.
FIG. 23 is an enlarged explanatory view of a part of FIG. FIG.
23, the same elements as those shown in FIGS. 1 and 2 are denoted by the same reference numerals. Next, the configuration of this embodiment will be described sequentially.

In FIG. 22, reference numeral 1 denotes a reduction projection optical system (projection lens system), and Ax denotes an optical axis of the projection optical system 1.
A reticle 1a has a circuit pattern formed on its surface, and is mounted on a reticle stage 1b. An illumination system 1c uniformly illuminates the surface of the reticle 1a. The projection optical system 1 reduces and projects the circuit pattern on the reticle 1a surface onto the wafer 2 surface. The wafer 2 is fixed on the wafer stage 3 by suction. The wafer stage 3 has an optical axis Ax direction (z direction) of the projection optical system 1 and an optical axis A
A plane (x-x) that is movable in two directions (x, y directions) in a plane orthogonal to x (x-y plane) and orthogonal to the optical axis Ax.
The inclination can be adjusted with respect to the (y plane). Thereby, the surface position of the wafer 2 placed on the surface of the wafer stage 3 can be arbitrarily adjusted. Reference numeral 4 denotes a stage control device, which controls driving of the wafer stage 3 based on a signal from a focus control device 18 described later.

SA is light irradiation means, SB is projection means, SC
Denotes photoelectric conversion means, which constitute a part of a surface position detecting device for detecting surface position information of the wafer 2 surface.
The projection means SB and the photoelectric conversion means SC use the detection means SB.
C.

In this embodiment, the circuit pattern on the reticle 1a surface is projected onto the wafer 2 by the projection optical system 1 using the surface position detecting device.
When projecting on the surface, the drive of the wafer stage 3 is controlled so that the exposure area on the surface of the wafer 2 is located within the allowable depth of focus of the projection optical system 1. Then, move the wafer stage 3 to X
The rectangular pattern area (shot) 39 is sequentially formed on the surface of the wafer 2 by sequentially moving on the −Y plane.

Next, each element of the surface position detecting device of this embodiment will be described. First, the light irradiating 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 comprises 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 a light beam from the light source 5 as a parallel light beam having a substantially uniform cross-sectional intensity distribution.

Numeral 7 is a prism-shaped slit member.
A pair of prisms are bonded together such that their slopes face each other, and the bonding surface has a plurality of openings (five pinholes) 71 to 75. Reference numeral 8 denotes a lens system, which is composed of both telecentric systems, and which transmits five independent light beams 71a to 75a passing through a plurality of pinholes 71 to 75 of the slit member 7 via a mirror 9 to five measurement points 19 on the wafer 2 surface. The light is guided at an incident angle substantially equal to ２３23.
At this time, the size of the projected image is set to be a pinhole image that is substantially equal. Also, this lens system 8 has each light beam 7 therein.
An aperture stop 40 for adjusting the NA of 1a to 75a is provided. In this embodiment, each of the above elements 5, 6, 7, 8,
9 constitutes light irradiation means SA.

In this embodiment, the incident angle φ of each light beam from the light irradiating means SA on the surface of the wafer 2 (the angle formed with a vertical line on the wafer surface) is φ = 70 ° or more. A plurality of pattern areas (exposure area shots) 39 are arranged on the surface of the wafer 2 as shown in FIG. The five light beams 71a to 75a that have passed through the lens system 8 are incident on the measurement points 19 to 23 independent of each other in the pattern area 39.

The five light beams 71a to 75a incident on the surface of the wafer 2 are perpendicular to the wafer 2 (the direction of the optical axis Ax).
23, a direction rotated by θ ° (θ = 22.5 °) in the XY plane from the X direction (shot arrangement direction) on the surface of the wafer 2 so as to be observed independently from each other as shown in FIG. More incident. Thereby, the same effect as in the first embodiment is obtained.

The five pinholes 7 of the slit member 7
1 to 75 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.
The size and shape of the pinholes 71 to 75 of the slit member 7 and the distance from the lens system 8 are set so that pinhole images having substantially the same size are formed on the surface of the wafer 2.

In this embodiment, each of the above elements 5, 6, 7,
A plurality of light beams (pinholes) are made incident on the surface of the wafer 2 by the light irradiating means SA composed of 8 and 9. In this embodiment, the number of measurement points on the surface of the wafer 2 is not limited to five but may be any number.

Next, a plurality of reflected light beams from the wafer 2
The projection unit SB that guides light onto the detection surface 17 of the photoelectric conversion unit SC as a position detection element made of a CD and forms an image will be described.

Reference numeral 11 denotes a light receiving lens, which is composed of both telecentric systems, and reflects five reflected light beams from the surface of the wafer 2 via the mirror 10. And the light receiving lens 11
Form a pinhole image at each position 24-28 with respect to each measurement point 19-23. Reference numeral 41 denotes a stopper provided on the light receiving lens 11, which has the same effect as that of the first embodiment. Light beams from the pinhole images at the respective positions 24 to 28 enter five independently provided correction optical systems 12 to 16.

Since the light receiving lens 11 is a bi-telecentric system, the optical axes of the correction optical systems 12 to 16 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. Re-imaging is performed on the surface 17 so that spot lights having the same size are formed. The photoelectric conversion means SC comprises a single two-dimensional CCD. In the present embodiment, the projection means SB is constituted by the above elements 10, 11, 12 to 16.

Each of the correction optical systems 12 to 16 has a plane-parallel plate having a predetermined thickness and a lens system.
It is coaxial or eccentric with respect to one optical axis. At this time, the parallel plane plate is used to correct the optical path length of each lens system. The lens system has a detection surface 17 at each of the measurement points 19 to 23.
It is provided to correct the above imaging magnification (projection magnification) so as to be substantially equal.

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 the present embodiment, a plurality of measurement points 19 to 23 having different distances from the light receiving lens 11 are connected to the photoelectric conversion means SC. When an image is formed on the detection surface 17, the imaging magnifications thereof are different from each other.

Therefore, in this embodiment, correction optical systems 12 to 16 are provided for each measurement point, and these measurement points 19 to 2 are provided.
The projection magnification on the detection surface 17 is set to be substantially equal (this correction optical system is described in detail in Japanese Patent Application No. 2-44236, filed by the present applicant).

At this time, each measurement point 19 on the wafer 2
The position of the pinhole image (spot light) incident on the detection surface 17 is changed depending on the surface positions (height direction, optical axis Ax direction) of No. to No. 23. The photoelectric conversion means SC detects a change in the position of the pinhole image at this time. Thus, in this embodiment, the surface position information of each of the measurement points 19 to 23 on the surface of the wafer 2 can be detected with the same accuracy.

The measurement points 19 to 23 on the surface of the wafer 2 and the detection surface 17 of the photoelectric conversion means SC are conjugate to each other via the projection means SB (for each of the measurement points 19 to 23, (Correcting the fall). 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
The position of the pinhole image on the detection surface 17 changes in response to a local change in 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 of the measurement points 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 of each measurement point 19 to 23 from C (surface position information)
From this, position information on the surface of the wafer 2, that is, a position in the optical axis Ax direction (z direction), an inclination with respect to the XY plane, and the like are obtained. Then, a signal relating to the driving amount of the wafer stage 3 is input to the stage control device 4 so that the surface of the wafer 2 substantially matches the projection surface of the reticle 1a by the projection optical system 1.

The stage controller 4 drives and controls the wafer stage 3 in accordance with an input signal from the focus controller 18 to adjust the position and orientation of the wafer 2.

The displacement of the wafer stage 3 in the xy direction 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. Is input to the stage control device 4.

The stage controller 4 controls the position of the wafer stage 3 in the xy directions, and moves the wafer stage 3 in the z direction based on a signal input from the focus controller 18 via a signal line. Control and tilt control. This is the same in the first embodiment.

Next, a method of detecting the surface position of the pattern area 39 on the wafer 2 in this embodiment will be described.

As described above, the main factors of the detection error generated when the surface position of the wafer 2 is detected by the optical surface position detecting device shown in FIG. 22 are the light reflected on the resist surface of the wafer 2 and the substrate surface of the wafer 2. This is interference with reflected light. Since the influence of the interference varies depending on the pattern formed on the wafer substrate surface, the measurement error due to the interference is different for each of the plurality of measurement points 19 to 23.

In the reduction projection exposure apparatus as shown in FIG. 22, the pattern on the reticle 1a is sequentially transferred to each exposure area on the wafer 2 by the step & repeat method.
At this time, before performing the surface position detection and the pattern transfer, the alignment between the IC pattern already formed in the exposure area of the wafer 2 and the reticle pattern is performed.

The optical surface position detecting device is a projection lens system 1
, And the reticle 1 a is also positioned at a fixed position with respect to the projection lens system 1. Therefore, if the surface position is detected after the reticle pattern is aligned with the exposure area of the wafer 2, the measurement points 19 to 23
Approximately the same height position in each exposure region arranged on the wafer 2 is detected.

This means that the measurement points 19 to 23 detect the height positions of the portions having the same substrate (pattern) structure in each exposure area.

Therefore, the influence of the interference between the light reflected on the resist surface of the wafer 2 and the light reflected on the substrate surface of the wafer 2 on the detection result may be a value specific to each measurement point in the exposure area. As expected, the inventor has confirmed by experiment that an almost constant detection error actually occurs in each measurement.

By applying this phenomenon to surface position detection, a detection error at each measurement point is measured in advance, and the detection error at each measurement point is calculated from surface position data for each measurement point in the exposure area. How to correct and get accurate surface position information,
The present applicant has proposed in Japanese Patent Application Laid-Open No. 2-102518.

In this publication, the positional relationship between the exposure area 39 and the measuring points 19 to 23 of the surface position detecting device is different from the rectangular connecting the measuring points 19, 20, 22, and 23 as shown in FIG. When the exposure area 39 is smaller, some of the plurality of measurement points may be located in the wafer area where there is no pattern at the periphery of the wafer.

In this case, the above-described detection error for each measurement point is corrected from the surface position data related to each measurement point in the exposure area around the wafer including the measurement point located in the wafer area having no pattern. If so, accurate surface position information may not be obtained.

Therefore, in the exposure area around the wafer,
It is necessary to perform wafer surface position measurement using a plurality of remaining measurement points excluding the measurement points located in the wafer region where there is no pattern. As a result, the number of measurement points in the peripheral portion of the wafer decreases, and the accuracy of correcting the surface position may deteriorate.

In this embodiment, the deterioration of the correction accuracy of the surface position in the exposure area in the peripheral portion of the wafer at this time is improved by the method described below.

FIG. 25 shows a layout of an exposure area 39 formed regularly on the wafer 2 along the x-axis and the y-axis.

At this time, the positional relationship between the exposure area 39 and the measuring points 19 to 23 of the surface position detecting device is such that a rectangular exposure connecting the measuring points 19, 20, 22, and 23 has a rectangular shape as shown in FIG. It is assumed that the area 39 is smaller. Then, whether each of the measurement points 19 to 23 is on the pattern,
As shown in FIG. 25, the exposure area is divided into nine areas A to I. Exposure area 39 (plural) in each area of A to I
The positional relationship between and the measurement points 19 to 23 is shown in a to i of FIG. In FIG. 26, a black circle indicates a case where there is a measurement point on the pattern, and a white circle indicates a case where there is no measurement point on the pattern.

That is, considering the area on the pattern and the area without the pattern for each of the measurement points 19 to 23, the following table is obtained.

[0196]

[Table 1] Here, for each of the measurement points 19 to 23, it is assumed that the detection error (offset correction amount) in the area on the pattern and the area not on the pattern is obtained.

First, a method of obtaining a detection error in an area where the measurement points 19 to 23 are on the pattern will be described.

As shown in FIG. 24, measurement points 19 to 23 are set for the exposure area 39, and the measurement point 21 is located substantially at the center of the exposure area 39. When the surface position is measured, the optical axis AX is set.
As described above, the mounting position of the surface position detecting device is adjusted in advance.

The remaining measurement points 19, 20, 22, 23 are:
At the periphery (outside) of the exposure area 39,
The origins of the height measurement of ２３23 are adjusted so as to be on the same plane, and this plane is made to substantially coincide with the best imaging plane of the reduction projection lens system 1.

Here, assuming that the measurement point 21 is located at the point (x, y) on the xy coordinates, the measurement points 19, 20, 22,
(X + δx, y + δy), (x +
δx, y−δy), (x−δx, y + δy), (x−δx,
y-δy). At this time, the origin of the xy coordinate system is the intersection between the xy plane and the optical axis AX.

Next, an exposure area 39 for offset measurement unique to each measurement point caused by the wafer structure.
Are determined in advance from the area A in which all the measurement points 19 to 23 are on the pattern.

First, the wafer stage 3 is moved so that the measurement point 21 is located in an area without a pattern outside the exposure area 39 on the wafer 2, and the height position measurement value of the measurement point 21 (optical axis A
The wafer 2 is fixed at a height position that is almost zero (X direction) (the position in the optical axis AX direction is a predetermined exposure region 39).
Shall be kept constant during the measurement. ).

This operation is necessary to set the origin of the height position measurement value (in the direction of the optical axis AX) of the measurement point 21 in an area where the pattern is not affected.

Then, by moving the wafer stage 3 stepwise, one of a plurality of predetermined exposure areas 39 on the wafer 2 is sequentially sent directly below the projection lens system 1 to align with the reticle pattern. . At this time, movement control of the wafer stage 3 is performed using an output signal from the laser interferometer.

Then, the direction of the optical axis AX at the measurement points 19 to 23 of the exposure region 39 on the wafer 2, that is, the height positions z ^pattern ₁₉ to z ^pattern ₂₃ are detected by the surface position detecting device. Signal corresponding to the height position z ^pattern ₁₉ ~z ^pattern ₂₃ is input from the position detection element 17 to the focus controller 18.

This measurement is to be performed sequentially for all of the plurality of predetermined exposure areas 39.

[0207] Here, the surface position at the measuring points 19 to 23 of each exposure area 39 on the wafer 2 z ^pattern ₁₉ ~z ^pattern
₂₃ is z ^pattern ₁₉ = f ₁₉ (x + δx, y + δy) + c ^pattern ₁₉ z ^pattern ₂₀ = f ₂₀ (x + δx, y−δy) + c ^pattern ₂₀ z ^pattern ₂₁ = f ₂₁ (x, y) + c ^pattern ₂₁ z ^pattern ₂₂ = F ₂₂ (x−δx, y + δy) + c ^pattern ₂₂ z ^pattern ₂₃ = f ₂₃ (x−δx, y−δy) + c ^pattern ₂₃

The method of obtaining the x and y coordinates of this function is shown in FIG.
4, 25. Since the actual surface position detection is performed for each specific exposure area to be detected, z
The values of ^pattern _{19 to} z ^pattern ₂₃ (surface position data) are x,
It becomes a discrete value for y. Δx and δy are shown in FIG.
Is the distance between each of the measurement points described with reference to FIG.

[0209] Thus, from the value of z ^pattern ₁₉ ~z ^pattern ₂₃ obtained for each measuring point 19 to 23 of the plurality of exposure regions 39, of each set (measurement point z ^pattern ₁₉ ~z ^pattern ₂₃ The surface shape of the wafer 2 can be estimated for each set. The above-mentioned f _{19 to} f ₂₃ represent, for each of the measurement points 19 to 23, functions of only x and y that do not include the constant term of the surface shape function obtained by, for example, polynomial approximation, and c ^pattern _{19 to} c ^pattern ₂₃
Indicates a constant term of the surface shape function.

The measured values at the respective measurement points 19 to 23 are
Even if the light reflected by the resist surface and the light reflected by the substrate surface of the wafer 2 are affected by the interference, the measurement points 19 to 23 detect the position of the wafer surface having the same surface shape of the substrate surface. There is no difference in what you do.

The z ^pattern _{19 to} z at each measurement point in each exposure area
The surface shape of the wafer 2 inferred from the value of the ^pattern ₂₃ should be exactly the same from the viewpoint of physically measuring the same surface, that is, the same wafer surface. However, since the surface position detection of each measurement point is affected by the interference of the substrate structure unique to each measurement point for each measurement of each exposure region as described above, there is a constant amount of constant shift.

Therefore, assuming that a true function indicating the surface shape of the wafer 2 is f (x, y), z ^pattern _{19 to} z ^pattern ₂₃
Can be rewritten as:

Z ^pattern ₁₉ = f (x + δx, y + δy) + c ^pattern ₁₉ z ^pattern ₂₀ = f (x + δx, y−δy) + c ^pattern ₂₀ z ^pattern ₂₁ = f (x, y) + c ^pattern ₂₁ z ^pattern ₂₂ = f ( x−δx, y + δy) + c ^pattern ₂₂ z ^pattern ₂₃ = f (x−δx, y−δy) + c ^pattern ₂₃ Here, the order and expansion formula of the surface of the surface shape function f (x, y) are given by a predetermined polynomial. since the predetermined form of the measured values z ^pattern ₁₉ ~z ^pattern ₂₃ a surface position de - used as data, minimum 2 surface shape at each measurement point by multiplicative function f (x,
The coefficients and constant terms c ^pattern _{19 to} c ^pattern ₂₃ of y) are calculated.

In this method, for example, the least squares method of ∬ [｛f ₂₁ (x, y) + c ^pattern ₂₁ ｝ −z ^pattern ₂₁ (x, y)] ² dxdy = 0 is solved for the measurement point 21. Execute the surface shape function f
₂₁ The coefficient of (x, y) and the constant term c ^pattern ₂₁ are determined.

Next, the surface shape function is represented by f (x, y) =
Other measurement points 19, 20, and 2 are defined as f21 (x, y).
For 2, 23, {[{f ₂₁ (x + δx, y + δy) + c ^pattern ₁₉ } −z ^pattern ₁₉ (x + δx, y + δy)] ² dxdy = 0 {[{f ₂₁ (x + δx, y−δy) + c ^pattern ₂₀ } − z ^pattern ₂₀ (x + δx, y−δy)] ² dxdy = 0∬ [｛f ₂₁ (x−δx, y + δy) + c ^pattern ₂₂ ｝ −z ^pattern ₂₂ (x−δx, y + δy)] ² dxdy = 0∬ [｛ f ₂₁ (x−δx, y−δy) + c ^pattern ₂₃ ｝ −z ^pattern ₂₃ (x−δx, y−δy)] ² dxdy = 0.

However, for the measurement points 19, 20, 22, and 23, the coefficient of the surface shape function f ₂₁ (x, y) is
Determined value against, i.e. a fixed value shall be determined only constant terms ^{_{c pattern 19, c pattern 23,}} c pattern 23, c pattern 23 with the least squares method.

The constant terms c ^pattern ₁₉ to c obtained here
^{Using the pattern} ₂₃ , an offset correction amount to be reflected at the time of surface position measurement is determined as described later.

Here, the calculation accuracy of the coefficient of the surface shape function f (x, y) increases as the measured value (surface position data) increases, so that the exposure to be detected is adjusted in accordance with the required correction accuracy. What is necessary is just to determine the number of areas.

The method of obtaining a detection error from the constant term of the surface shape function f (x, y) is disclosed in
No. 102,518. This method is hereinafter referred to as “surface shape function constant method”.

Next, a method of obtaining a detection error in an area where the measurement points 19, 20, 22, and 23 are not on the pattern will be described.

As described above, in the surface position detecting apparatus of this embodiment, the pinhole images on the measuring points 19 to 23 are formed almost equally, and the correction optical system is provided for each measuring point. The magnification, resolution, and accuracy for detecting the height position of each of a plurality of measurement points are substantially equal to each other. Further, the aperture stop 40 provided in the lens system 8
Are almost the same, and the exit side is made telecentric by the lens system 8, and the measuring points 19 to 75 of the light fluxes 71a to 75a are set.
23 are incident at substantially the same angle.

That is, the surface position detecting device of this embodiment is
The optical characteristics of the plurality of measurement points 19 to 23 are all equal.

Therefore, the measurement points 19, 20, 22, 23
Since the detection error of the area where the pattern is not above the pattern shows the same value if the substrate structure under the measurement point is the same, the result is the same regardless of which measurement point is used among the measurement points. Indicates a thing.

By using this fact, a detection error in an area not on the pattern is determined.

First, each exposure area 3 for measuring a detection error
9, B, C, D, E where the measurement point 19 is not on the pattern
It is assumed that a plurality of sections are determined in advance from each of the sections. The aforementioned “surface shape function constant method” is performed on the predetermined exposure region 39. At this time, the measurement is performed using all the measurement points 19 to 23.

Wafer 2 at measurement points 19, 20, 22, and 23
The measured value in the optical axis AX direction of the upper exposure area 39 is z ^outside ,
The surface shape function is f (X, Y), and the wafer 2 at the measurement point 21 is
The measured value of the upper exposure area 39 in the optical axis AX direction is z ′ ^pattern ₂₁ , and the surface shape function is f (x, y).

Then, the surface positions z ^outside and z ' ^pattern ₂₁
Is as follows: z ^outside = f (X, Y) + c ^outside z ′ ^pattern ₂₁ = f (x, y) + c ′ ^pattern ₂₁

At this time, z ^outside , f (X, Y) takes the following values depending on the area. That is, in the area B, the values of the measurement points 19 and 22 are obtained, and z ^outside (X, Y) = z ^outside ₁₉ (x + δx, y + δy) f (X, Y) = f (x + δx, y + δy) and z ^outside (X, Y Y) = z ^outside ₂₂ (x−δx, y + δy) f (X, Y) = f (x−δx, y + δy) In the area C, the values of the measurement points 19 and 20 are obtained, and z ^outside (X, Y) = z ^outside ₁₉ (x + δx, y + δy) f (X, Y) = f (x + δx, y + δy) and z ^outside (X, Y) = z ^outside ₂₀ (x + δx, y−δy) f (X, Y) = f (x + δx, y-δy) In the D area, the values of the measurement points 20 and 23 are obtained. z ^outside (X, Y) = z ^outside ₂₀ (x + δx, y-δy) f (X, Y) = f (x + δx, y-δy) and z ^outside (X, Y) = z ^outside ₂₃ (x−δx, y−δy) f (X, Y) = f (x−δx, y− δy) In the area E, the values of the measurement points 22 and 23 are obtained. z ^outside (X, Y) = z ^outside ₂₂ (x−δx, y + δy) f (X, Y) = f (x−δx, y + δy) and z ^outside (X, Y) = z ^outside ₂₃ (x−δx, y−δy) f (X, Y) = f (x−δx, y−δy)

The coefficient and constant term c ^outside _{19 of} the surface shape function f (X, Y) and the coefficient and constant term c of f (x, y)
^{The pattern} ₂₁ is calculated by the least squares method using the measured values z ^pattern and z ′ ^pattern ₂₁ as surface position data.

In this method, the minimum of {[{f ₂₁ (x, y) + c ′ ^pattern ₂₁ } −z ′ ^pattern ₂₁ (x, y)] ² dxdy = 0 is obtained for the measurement point 21 as described above. It is executed to solve the square method, and the surface shape function f
₂₁ The coefficient of (x, y) and the constant term c ′ ^pattern ₂₁ are determined.

Next, the surface shape function is represented by f (X, Y) =
As f ₂₁ (X, Y), the operation is performed so as to solve the least squares method of ｛[｛f ₂₁ (X, Y) + c ^outside ｝ −z ^outside (X, Y)] ² dXdY = 0.

However, the coefficient of the shape function f ₂₁ (x, y) is a value determined for the measurement point 21, that is, a fixed value, and only the constant term c ^outside is determined by the least square method.

In this way, the measurement points 19, 20, 22,
If the detection error is obtained in the peripheral area where the pattern 23 is not on the pattern, the number of shots that can be selected for the detection error measurement in the layout of the exposure area 39 shown in FIG. Thus, the number of shots that can be selected from the area A in the area A is more than 12, and it is possible to obtain the detection error in the peripheral area with the same or higher accuracy as the area A.

The constant terms c ^outside , c ′ obtained here
^{Using the pattern} ₂₁ , an offset correction amount to be reflected at the time of surface position measurement is determined as described later.

As described above, the detection errors in the area where the measurement points 19 to 23 are above the pattern and in the area where the measurement points 19, 20, 22, and 23 are not above the pattern were obtained. next,
A method of calculating an offset to be reflected when measuring a surface position will be described.

The obtained constant terms c ^pattern _{19 to} c
^{The pattern} ₂₃ , c ^outside , and c ′ ^pattern ₂₁ may be used as an offset.

That is, assuming that the respective offsets when the measurement points 19 to 23 are on the pattern are PT ₁₉ to PT ₂₃ , PT ₁₉ = c ^pattern ₁₉ PT ₂₀ = c ^pattern ₂₀ PT ₂₁ = c ^pattern ₂₁ PT ₂₂ = c ^pattern ₂₂ PT ₂₃ = c ^pattern ₂₃

When the measurement points 19, 20, 22, and 23 are not on the pattern, the offset of each measurement point is OS in common, and OS = c ^outside .

(Here, since c ^pattern ₂₁ = c ′ ^pattern ₂₁ , c ^pattern ₂₁ was used as the offset PT ₂₁ of the measurement point 21.) The offset of the measurement point 21 was set to the pattern on the wafer. The value may be obtained by exposure and an experiment, or may be a value automatically measured by another method proposed by the present applicant in Japanese Patent Application Laid-Open No. 2-198130. This value is assumed to be CT and stored in the memory in advance.

That is, PT ₂₁ = CT.

At this time, when the measurement points 19, 20, 22, and 23 are on the pattern, the respective offsets are: PT ₁₉ = c ^pattern ₁₉ -c ^pattern ₂₁ + CT PT ₂₀ = c ^pattern ₂₀ -c ^pattern ₂₁ + CT PT ₂₂ = c ^pattern _22- c ^pattern ₂₁ + CT PT ₂₃ = c ^pattern _23- c ^pattern ₂₁ + CT

When the measurement points 19, 20, 22, and 23 are not on the pattern, the offset of each measurement point is as follows: OS = c ^outside −c ′ ^pattern ₂₁ + CT

As described above, the offset of the measurement point 21 is obtained by an experiment or the like, and the other offsets PT _{19 to} PT ₂₃ are obtained as the difference of the constant term c ^pattern ₂₁ of the measurement point 21.
By calculating S as the difference of the constant term c ′ ^pattern ₂₁ of the measurement points 21, the offsets PT _{19 to} P
The reliability of _T23 and the OS can be improved.

The offsets PT ₁₉ -P determined here are
T ₂₃ and OS are stored in memory.

Now that the offset to be reflected on each measurement point has been set, how to reflect the offset at the time of exposure will be described.

After the offset setting is completed, the first
The wafer stage 3 is moved so that the exposure area is directly below the projection lens system 1, and the first exposure area is aligned with the reticle pattern. After the alignment is completed, the surface positions of the five measurement points 19 to 23 in the first exposure area are detected by the surface position detection device, and the respective measurement points are detected in the focus control device 18 based on the output signal from the photoelectric conversion means SC. Form surface position data.

[0247] The focus control unit 18, a memory - and designed to read the offset OFS ₁₉ ~OFS ₂₃ of each measuring point 19-23 from. At this time, the first exposure region in belongs to the area (A to I) of FIG. 25 throat, offset OFS ₁₉ ~OFS ₂₃ reading shall take values in accordance with the table below.

[0248]

[Table 2] Values Z ₁₉ -Z obtained by correcting the surface position data z ₁₉ -z ₂₃ of the first exposure area by the read offsets OFS ₁₉ -OFS _23.
Calculate ₂₃ .

That is, it is assumed that Z ₁₉ = z ₁₉ -OFS ₁₉ Z ₂₀ = z ₂₀ -OFS ₂₀ Z ₂₁ = z ₂₁ -OFS ₂₁ Z ₂₂ = z ₂₂ -OFS ₂₂ Z ₂₃ = z ₂₃ -OFS ₂₃ . Focus control unit 18, based on this new surface position data Z ₁₉ to Z _23, determining the least square plane of the first exposure region.

Further, the focus control device 18 inputs a command signal corresponding to the calculated result of the least square plane to the stage control device 4 so that the position and the inclination of the wafer 2 on the wafer stage 3 in the optical axis AX direction are determined. It is adjusted (corrected). As a result, the first exposure area on the wafer 2 is positioned at the best image forming plane of the projection lens system 1. After the adjustment of the surface position, the first exposure area is exposed to transfer the reticle pattern.

When the exposure for the first exposure area is completed,
The wafer stage 3 is driven so that the second exposure area on the wafer 2 is directly below the projection lens system 1, and the same surface position detection, surface position adjustment, and exposure operation as described above are performed. After performing this series of operations until the exposure of the final exposure area is completed,
The wafer 2 is unloaded from the wafer stage 3.

The above-described determination of the detection error (offset correction amount) at each measurement point on the wafer surface needs to be performed for each process in which a pattern to be formed is different.

However, it is sufficient that the frequency be performed once for each step. If the detection error (offset correction amount) is determined at the beginning of each step and the value is stored in the memory in the control device, Production can be performed with almost no reduction in the throughput of semiconductor chip production.

Since the offset correction amount caused by the detection is a value unique to each measurement point, the number of exposure areas (the number of shots) used to determine a surface shape function (including a constant term)
Is appropriately determined from the focus accuracy required for the apparatus.

That is, a small number is required in a step where the demand for the focus accuracy is loose, and a large number is required in a step where the demand is low. However, even if the number of measurement shots in the area A and the surrounding area is 24 in total, the time required for stepping between each shot is 0.4 seconds, and the measurement time is 0.2 seconds, the offset accompanying the detection The time required to determine the correction amount is less than about 15 seconds. As described above, the detection offset correction amount is determined only for the first wafer of a large number of lots in each lot, and for the subsequent wafers, the value obtained for the first wafer is used. The drop is almost negligible.

Further, after the measurement in the areas A and B to E is performed simultaneously, the detection errors c ^pattern _{19 to} c ^pattern
₂₃ and c ^outside may be calculated.

The measurement procedure in this case is shown in FIGS.
This is simply shown in the flowchart of FIG.

In the above embodiment, the measurement point 2 in the area A is used.
1 is performed so as to solve the least-squares method such that ｛[｛f ₂₁ (x, y) + c ^pattern ₂₁ ｝ −z ^pattern ₂₁ (x, y)] ² dxdy = 0, and the surface shape function f 21
(X, y) coefficient and constant term cpattern21
Is determined, and the constant terms c ^pattern ₁₉ , ₂₀ , ₂₂ , and
₂₃ , the surface shape function f (x, y) = f ₂₁ (x,
y).

Here, the least squares method may be solved for other measurement points in the area A, and the constant term of the remaining measurement points may be determined using the surface shape function obtained for this measurement point. .

Further, the least squares method is solved for each of the measurement points 19 to 23 in the area A, and the surface shape function f ₁₉ (x, y)
To f ₂₃ (x, y), and f ₁₉ (x, y) to f ₂₃ (x, y).
The function obtained by averaging the coefficients of each order of y) is f
_average (x, y).

Then, the surface shape function f (x, y) = f
_{As the average} (x, y), the least squares method is again solved for all the measurement points 19 to 23, and the constant terms c ^pattern _{19 to} c
^{When the pattern} ₂₃ is determined, the calculation accuracy of the surface shape function f (x, y) is improved by the large number of samples.
The calculation accuracy of ^pattern _{19 to} c ^pattern ₂₃ is also improved.

FIG. 30 shows a wafer 2 according to the second embodiment of the present invention.
It is explanatory drawing of the upper pattern area. In the present embodiment, the positional relationship between the exposure area 39 and the measurement points 19 to 23 of the surface position detecting device is such that the rectangle connecting the measurement points 19, 20, 22, and 23 and the rectangle of the exposure area 39 are almost as shown in FIG. It is an example in the case of being equal.

Depending on whether each of the measurement points 19 to 23 is on the pattern or on the boundary, the exposure area is divided into 17 areas A to Q as shown in FIG.

When each measurement point is on the boundary of the pattern, there are 12 possible positional relationships as shown in case-1 to case-12 in FIG. In FIG. 32, circles represent measurement points,
The hatched portion shows a part of the measurement point on the pattern. The presence of twelve types of positional relationship between the measurement point and the pattern boundary means that there are also twelve types of detection errors (offset correction amounts) in the area where the measurement point is in the boundary region.

Here, when the area on the pattern and the area in the boundary area are considered for each of the measurement points 19 to 23, the following table is obtained.

[0266]

[Table 3] Furthermore, in the area in the boundary area, the measurement points 19, 20, 2
As shown in the table below, Nos. 2 and 23 differ in the positional relationship between the measurement point and the pattern.

[0267]

[Table 4] Then, there are five types of detection errors in the area above the pattern, and 1 in the area in the boundary area with the pattern.
It is necessary to find two types, that is, a total of 17 types of detection errors.

Hereinafter, a method for simultaneously obtaining the detection error of the area where the measurement point is above the pattern and the detection error of the area where the measurement point is in the boundary area with the pattern will be described.

First, an exposure area 3 for measuring a detection error
9 is determined in advance from at least one shot or more from the B to Q areas (in this case, 16 shots or more. The area of A may be included).

First, the wafer stage 3 is moved so that the measurement point 21 is located in an area without a pattern outside the exposure area 39 on the wafer 2, and the height position measurement value of the measurement point 21 (optical axis A
The wafer 2 is fixed at a height position where the height is almost zero (X direction) (the position in the optical axis AX direction is to be kept constant during the subsequent measurement of the exposure area 39 in the remaining B to Q areas). .).

This operation is necessary for setting the origin of the height position measurement value (optical axis AX direction) of the measurement point 21 in an area where the pattern is not affected.

By moving the wafer stage 3 stepwise, a predetermined exposure area 39 in the area B is set.
Is sent directly below the projection lens system 1 to align with the reticle pattern. At this time, movement control of the wafer stage 3 is performed using an output signal from the laser interferometer.

Then, the measurement point 1 of the exposure area 39 in the B area
The optical axis AX direction of 9 to 23, i.e. the height position _{z 19, z 20, z 21} , z 22, z 23, is detected by the surface position detecting apparatus. A signal corresponding to each height position is input from the photoelectric conversion unit SC to the focus control device 18. This measurement is sequentially performed on all of the predetermined exposure regions 39 in the B to Q areas.

Next, calculation is performed using the measurement points 21 existing on the pattern in all the exposure areas 39 in the B to Q areas.

That is, the surface position z21 of the measurement point 21 in each of the exposure areas 39 in the B to Q areas is represented by the surface shape function z ^pattern ₂₁ = f ₂₁ (x, y) + c ^pattern _{21 in the same} manner as described above. And

The above f ₂₁ (x, y) represents a function of only x and y which does not include the constant term of the surface shape function obtained by the polynomial approximation or the like for each measurement point 21, and c ^pattern ₂₁ represents this surface shape. Indicates the constant term of the function.

[0277] Here, the surface shape function f ₂₁ (x, y) curved surface of degree and deployment type, since predetermined in the form of a predetermined polynomial, surface position measurements z ₂₁ of B~Q zone Using the data as the data, the surface shape function f ₂₁ (x,
The coefficient of y) and the constant term c ^pattern ₂₁ are calculated.

This method may be executed so as to solve the following equation: {[{f ₂₁ (x, y) + c ^pattern ₂₁ } −z ₂₁ (x, y)] ² dxdy = 0.

The obtained constant term c ^pattern ₂₁ is used to determine an offset correction amount to be reflected at the time of surface position measurement, as described later. The surface shape function f ₂₁ (x, y) obtained here is the measurement point 19 , 20, 22, and 23 are used to determine the offset associated with the detection.

First, a method of obtaining a detection error in an area where the measurement points 19, 20, 22, and 23 are on the pattern will be described.

As for the measurement point 19, in the D, E, G, H, I, O, and P areas where the measurement point 19 is on the pattern,
The measured value of the surface position is z ^pattern ₁₉ . Then, the surface shape function of the measurement point 19 in this area is represented by f (X, Y) + c ^pattern
_{19 is} assumed. At this time, c ^pattern ₁₉ is a constant term of the surface shape function.

Here, it is assumed that the z ^pattern ₁₉ and the surface shape function f (X, Y) not including the constant term take the following values in each of the above-mentioned areas.

Z ^pattern ₁₉ (X, Y) = z ^pattern ₁₉ (x + δx, y + δy) f (X, Y) = f ₂₁ (x + δx, y + δy) f ₂₁ (x + δx, y + δy) is , The surface shape function f ₂₁ (x,
y), coordinate values (x + δx, y + δ) corresponding to the measurement point 19
y).

Then, as described above, z ^pattern ₁₉ (x + δx, y + δy) = f ₂₁ (x + δx, y + δy) + c ^pattern ₁₉ can be expressed.

The coefficients of the surface shape function f ₂₁ (x, y) are fixed to values obtained by executing the least squares method on the above-mentioned measurement points 21 and D, E, G, H, I , O, and P, the measured value z ^pattern ₁₉ is used as the surface position data, and only the constant term c ^pattern ₁₉ is newly calculated using the least squares method.

In this method, the coefficient of f ₂₁ (x, y) is fixed and is not subjected to the least squares method. For the constant term c ^pattern ₁₉ , {[{f ₂₁ (x + δx, y + δy) + c ^pattern ₁₉ } −z ^pattern ₁₉ (x + δx, y + δy)] ² dxdy = 0.

In the same manner as described above, for the measurement point 20, B, E, F, H, I, J,
Measurements z ^pattern ₂₀ in the Q area surface position de - used as data, the coefficient of f ₂₁ (x, y) is not fixed to the minimum square method of the subject, with respect to the constant term c ^pattern _20, ∬ [{ f ₂₁ (x + δx, y−δy) + c ^pattern ₂₀ ｝ −z ^pattern ₂₀ (x + δx, y−δy)] ² dxdy = 0

As for the measurement point 22, the measurement value z ^pattern ₂₂ of the C, D, F, G, H, M, and N areas where the measurement point 22 is on the pattern is used as the surface position data, and f ₂₁ ( x,
The coefficient of y) is fixed and not subject to the least squares method. For the constant term c ^pattern ₂₂ , ∬ [｛f ₂₁ (x−δx, y + δy) + c ^pattern ₂₂ ｝ −z ^pattern ₂₂ (x−δx, y + δy) )] ² dxdy = 0.

As for the measurement point 23, the measurement value z ^pattern ₂₃ in the B, C, F, G, I, K, and L areas where the measurement point 23 is on the pattern is used as the surface position data, and f ₂₁ ( x,
The coefficient of y) is fixed and not subjected to the method of least squares, and for the constant term c ^pattern ₂₃ , ｛[｛f ₂₁ (x−δx, y−δy) + c ^pattern ₂₃ ｝ −z ^pattern ₂₃ (x−δx , Y−δy)] ² dxdy = 0.

The constant terms c ^pattern ₁₉ and c obtained here
^{The pattern} ₂₀ , c ^pattern ₂₁ , and c ^pattern ₂₃ are used to determine an offset correction amount to be reflected at the time of surface position measurement as described later.

Next, a method of obtaining the detection offset in an area where the measurement points 19, 20, 22, and 23 are on the boundary of the pattern will be described below.

The positional relationship between the measurement points and the pattern is shown in FIG.
The case where the arrangement is as shown in case-1 will be described.

The measurement points in the arrangement shown in case-1 in FIG. 32 are measurement point 19 in the B and J areas and measurement point 2 in the B and K areas.
2. Then, the measured value of the surface position of the measurement points 19 and 22 in this area is 1z ^border ₁ , and the surface shape function is f (X, Y)
+ C ^border ₁ At this time, c ^border ₁ is a constant term of the surface shape function.

Then, the surface position z ^border ₁ becomes z ^border ₁ = f (X, Y) + c ^border ₁ .

Here, it is assumed that z ^border ₁ and the surface shape function f (X, Y) not including a constant term take the following values in the B area. _{^{That, z border 1 (X, Y}} ) = z pattern 19 (x + δx, y + δy) f (X, Y) = f 21 (x + δx, y + δy) and z border 1 (X, Y) = z pattern 22 (x-δx , Y + δy) f (X, Y) = f ₂₁ (x−δx, y + δy), and f ₂₁ (x + δx, y + δy) is applied to the surface shape function f ₂₁ (x, y) at the measurement points 19 and 22 in the same manner as described above. The corresponding coordinate values (x + δx, y + δy) and (x−δx, y + δ
y).

Similarly, in the J area, the value of z ^border ₁ (X, Y) = z ^pattern ₁₉ (x + δx, y + δy) f (X, Y) = f ₂₁ (x + δx, y + δy), and in the K area, z ^{border 1} ₁ (X, Y) = z ^pattern ₂₂ (x−δx, y + δy) f (X, Y) = f ₂₁ (x−δx, y + δy)

Then, the measured value z ^{border of the} B, J, K areas
₁ the surface position de - used as data, the coefficient of the surface shape function f ₂₁ is not fixed to the minimum square method of the subject, to perform the method of least squares with respect to the constant term c ^border _1.

That is, the equation of {[{f (X, Y) + c ^border ₁ } −z ^border ₁ (X, Y)] ² dXdY = 0 may be solved.

The measurement points in the arrangement shown in case-2 of FIG. 32 are measurement point 20 in the D and O areas and measurement point 2 in the D and N areas.
3. Then, the measured value of the surface position of the measurement points 20 and 23 in this area is z ^border ₂ , and the surface shape function is f (X, Y) +
^Let c ^border ₂ .

Then, the measured value z ^{border of the} D, N, O area
₂ the surface position de - used as data, the coefficient of the surface shape function f ₂₁ is fixed and performs the least square method with respect to the constant term c ^border _2.

That is, the equation of {[｛f (X, Y) + c ^border ₂ ｝ −z ^border ₂ (X, Y)] ² dXdY = 0 may be solved.

The measurement points in the arrangement shown in case-3 in FIG. 32 are measurement point 19 in the C and M areas and measurement point 2 in the C and L areas.
0. The measured value of the surface position of the measurement points 19 and 20 in this area is z ^border ₃ , and the surface shape function is f (X, Y) +
c ^border ₃

Then, the measured values z ^{border of the} C, M and L areas
₃ the surface position de - used as data, the coefficient of the surface shape function f ₂₁ is fixed and performs the least square method with respect to the constant term c ^border _3.

That is, the following equation may be solved: {[{f (X, Y) + c ^border ₃ } −z ^border ₃ (X, Y)] ² dXdY = 0.

The measurement points in the arrangement shown in case-4 in FIG. 32 are measurement point 22 in the E and P areas and measurement point 2 in the E and Q areas.
3. Then, the measured value of the surface position of the measurement points 22 and 23 in this area is z ^border ₄ , and the surface shape function is f (X, Y) +
c ^border ₄ .

Then, the measured values z ^{border of the} E, P, and Q areas
₄ the surface position de - used as data, the coefficient of the surface shape function f ₂₁ is fixed and performs the least square method with respect to the constant term c ^border _4.

That is, the equation of {[{f (X, Y) + c ^border ₄ } −z ^border ₄ (X, Y)] ² dXdY = 0 may be solved.

In case-2 to case-4, the measured value z
^border ₂ , z ^border ₃ , z ^border ₄ and surface shape function f
(X, Y) is defined in the same manner as in case-1 depending on each area, but the value is different. The detailed description is the same as described above, and will not be repeated.

The positional relationship between the measurement point and the pattern is shown in FIG.
The case where the arrangement is as shown in case-5 will be described. Of FIG.
The measurement point in the arrangement shown in case-5 is the measurement point 1 in the F area.
9, a measurement point 20 in the K area and a measurement point 22 in the L area. Then, the measured values of the surface positions of the measurement points 19, 20, and 22 in this area are z ^border ₅ , and the surface shape function is f (X, Y) +
^Let c ^border ₅ . At this time, c ^border ₅ is a constant term of the surface shape function.

Then, the surface position z ^border ₅ becomes z ^border ₅ = f (X, Y) + c ^border ₅ .

Here, it is assumed that z ^border ₅ and the surface shape function f (X, Y) not including the constant term take the following values in the F area.

That is, z ^border ₅ (X, Y) = z ^pattern ₁₉ (x + δx, y + δy) f (X, Y) = f ₂₁ (x + δx, y + δy), and f ₂₁ (x + δx, y + δy) is the same as described above. The coordinate value (x + δx, y + δy) corresponding to the measurement point 19 is substituted into the surface shape function f ₂₁ (x, y).

Similarly, in the K area, the value of z ^border ₅ (X, Y) = z ^pattern ₂₀ (x + δx, y-δy) f (X, Y) = f ₂₁ (x + δx, y-δy) is obtained. Then, the value of z ^border ₅ (X, Y) = z ^pattern ₂₂ (x−δx, y + δy) f (X, Y) = f ₂₁ (x−δx, y + δy) is obtained.

Then, the measured values z ^{border of the} F, K, and L areas
₅ surface position de - used as data, the coefficient of the surface shape function f ₂₁ is not fixed to the minimum square method of the subject, to perform the method of least squares with respect to the constant term c ^border _5.

That is, the equation of {[{f (X, Y) + c ^border ₅ } −z ^border ₅ (X, Y)] ² dXdY = 0 may be solved.

The measurement points in the arrangement shown in case-6 of FIG. 32 are the measurement point 19 in the Q area, the measurement point 22 in the I area, and J
The measurement point 23 of the area. Then, the measured value of the surface position of the measurement points 19, 22, and 23 in this area is z ^border ₆ , and the surface shape function is f (X, Y) + c ^border ₆ .

Then, the measured values z ^{border of the} Q, I, and J areas
₆ surface position de - used as data, the coefficient of the surface shape function f ₂₁ is fixed and performs the least square method with respect to the constant term c ^border _6.

That is, the equation of {[解 f (X, Y) + c ^border ₆ ｝ −z ^border ₆ (X, Y)] ² dXdY = 0 may be solved.

The measurement points in the arrangement shown in case-7 in FIG. 32 are the measurement point 20 in the P area, the measurement point 22 in the O area, and H
The measurement point 23 of the area. Then, z ^border ₇ measurements of the surface position of the measuring points 20, 22, 23 in this zone, the surface shape function f (X, Y) + a c ^border _7.

Then, the measured values z ^{border of the} P, O, and H areas
₇ surface position de - used as data, the coefficient of the surface shape function f21 is fixed and performs the least square method with respect to the constant term c ^border _7.

That is, the equation of {[解 f (X, Y) + c ^border ₇ ｝ −z ^border ₇ (X, Y)] ² dXdY = 0 may be solved.

The measurement points in the arrangement shown in case-8 of FIG. 32 include the measurement point 19 in the N area, the measurement point 20 in the G area, and
The measurement point 23 of the area. Then, the measured values of the surface positions of the measurement points 19, 20, and 23 in this area are set to z ^border ₈ , and the surface shape function is set to f (X, Y) + c ^border ₈ . And N,
The measured value z ^border ₈ of the G and M areas is used as surface position data, the coefficient of the surface shape function f ₂₁ is fixed, and the constant term c ^border
_The least squares method is performed on ₈ .

That is, the equation of {[解 f (X, Y) + c ^border ₈ ｝ −z ^border ₈ (X, Y)] ² dXdY = 0 may be solved.

In cases 6 to 8, the measured values z
^border ₆ , z ^border ₇ , z ^border _8, and the surface shape function f (X,
Y) is defined in the same way as in case-5, but with different values, depending on each zone. The detailed description is the same as described above, and will not be repeated.

The positional relationship between the measurement points and the pattern is shown in FIG.
The case where the arrangement is as shown in case-9 will be described. Of FIG.
The measurement points in the arrangement shown in case-9 are the measurement points 23 in the O and P areas. Then, the measured value of the surface position of the measurement point 23 in this area is z ^border ₉ , and the surface shape function is f (X, Y) + c
^border ₉ At this time, c ^border ₉ is a constant term of the surface shape function.

Then, the surface position z ^border ₉ becomes z ^border ₉ = f (X, Y) + c ^border ₉ .

Here, it is assumed that z ^border ₉ and the surface shape function f (X, Y) not including a constant term take the following values in the O and P areas.

That is, z ^border ₉ (X, Y) = z ^pattern ₂₃ (x−δx, y−δy) f (X, Y) = f ₂₁ (x−δx, y−δy), and f ₂₁ (x −δx, y−δy) is obtained by substituting the coordinate values (x−δx, y−δy) corresponding to the measurement point 23 into the surface shape function f ₂₁ (x, y) as described above.

[0329] Then, O, measured values z ^border ₉ of P zone surface position de - used as data, the coefficient of the surface shape function f21 without fixing with the least squares method of the subject, the minimum relative constant term c ^border ₉ Perform the square method.

That is, the following equation may be solved: {[{f (X, Y) + c ^border ₉ } −zb ^border ₉ X, Y)] ² dXdY = 0.

The measurement points in the arrangement shown in case-10 of FIG. 32 are the measurement points 20 in the M and N areas. The measured value of the surface position of the measurement point 20 in this area is z ^border ₁₀ , and the surface shape function is f
(X, Y) + c ^border ₁₀ Then, the measured value z ^border ₁₀ of the M and N areas is used as surface position data, the coefficient of the surface shape function f ₂₁ is fixed, and the least square method is performed on the constant term c ^border ₁₀ .

That is, the equation of {[{f (X, Y) + c ^border ₁₀ } −z ^border ₁₀ (X, Y)] ² dXdY = 0 may be solved.

The measurement points in the arrangement shown in case-11 of FIG. 32 are the measurement points 19 in the K and L areas. The measured value of the surface position of the measurement point 19 in this area is z ^border ₁₁ , and the surface shape function is f
(X, Y) + c ^border ₁₁ Then, the measured values z ^border ₁₁ of the K and L areas are used as surface position data, the coefficient of the surface shape function f ₂₁ is fixed, and the least square method is performed on the constant term c ^border ₁₁ .

That is, the equation of {[{f (X, Y) + c ^border ₁₁ } −z ^border ₁₁ (X, Y)] ² dXdY = 0 may be solved.

The measurement points in the arrangement shown in case-12 in FIG. 32 are the measurement points 22 in the J and O areas. The measured value of the surface position of the measurement point 22 in this area is z ^border ₁₂ , and the surface shape function is f
(X, Y) + c ^border ₁₂ Then, the measured value z ^border ₁₂ of the J and O areas is used as surface position data, the coefficient of the surface shape function f ₂₁ is fixed, and the least square method is performed on the constant term c ^border ₁₂ .

That is, the following equation may be solved: {[｛f (X, Y) + c ^border ₁₂ ｝ −z ^border ₁₂ (X, Y)] ² dXdY = 0.

Note that, in cases 10 to 12, the measured value z
^border ₁₀ , z ^border ₁₁ , z ^border _12, and surface shape function f
(X, Y) is defined in the same way as in case-9, but has different values, depending on each zone. The detailed description is the same as described above, and will not be repeated.

As described above, the detection offset in the area where the measurement points 19 to 23 are on the pattern and the detection offset in the area where the measurement points 19, 20, 22, and 23 are on the pattern boundary are obtained.

The next calculated constant term c ^pattern _{19 to} c
^pattern ₂₃ and, using each of the values of c ^border ₁ ~c ^border _12, to calculate an offset to be reflected upon Similarly surface position measurement and the above-described embodiments.

That is, assuming that the respective offsets when the measurement points 19 to 23 are on the pattern are PT ₁₉ to PT ₂₃ , PT ₁₉ = c ^pattern ₁₉ PT ₂₀ = c ^pattern ₂₀ PT ₂₁ = c ^pattern ₂₁ PT ₂₂ = c ^pattern ₂₂ PT ₂₃ = c ^pattern ₂₃

When the measurement points 19, 20, 22, and 23 are on the boundary of the pattern, the offset of each measurement point is represented by BD ₁ to BD ₁ .
Assuming BD ₁₂ , BD ₁ = c ^border ₁ BD ₂ = c ^border ₂ BD ₃ = c ^border ₃ BD ₄ = c ^border ₄ BD ₅ = c ^border ₅ BD ₆ = c ^border ₆ BD ₇ = c ^border ₇ BD ₈ = c ^border ₈ BD ₉ = c ^border ₉ BD ₁₀ = c ^border ₁₀ BD ₁₁ = c ^border ₁₁ BD ₁₂ = c ^border ₁₂

When the offset with respect to the measurement point 21 is a CT obtained in advance by an experiment or the like in the same manner as in the above-described embodiment, each of the cases where the measurement points 19, 20, 22, and 23 are on the pattern is obtained. the offset PT _19, PT _20, P
When _{T 22, PT 23, PT 19} = c pattern 19 -c pattern 21 + CT PT 20 = c pattern 20 -c pattern 21 + CT PT 22 = c pattern 22 -c pattern 21 + CT PT 23 = c pattern 23 -c pattern ₂₁ + CT.

When the measurement points 19, 20, 22, and 23 are on the boundary of the pattern, the offset of each measurement point is represented by BD ₁ to BD ₁ .
Assuming BD ₁₂ , BD ₁ = c ^border ₁ -c ^pattern ₂₁ + CT BD ₂ = c ^border ₂ -c ^pattern ₂₁ + CT BD ₃ = c ^border ₃ -c ^pattern ₂₁ + CT BD ₄ = c ^border ₄ -c ^pattern ₂₁ + CT BD ^{_{5 = c border 5 -c pattern 21}} + CT BD 6 = c border 6 -c pattern 21 + CT BD 7 = c border 7 -c pattern 21 + CT BD 8 = c border 8 -c pattern 21 + CT BD 9 = c border 9 - c ^pattern ₂₁ + CT BD ₁₀ = c ^border ₁₀ -c ^pattern ₂₁ + CT BD ₁₁ = c ^border ₁₁ -c ^pattern ₂₁ + CT BD ₁₂ = c ^border ₁₂ -c ^pattern ₂₁ + CT

The offsets PT _{19 to} PT determined here
Stores ₂₃ and 12 offset BD ₁ ~BD ₁₂ into memory.

Thus, the offset to be reflected on each measurement point has been set. The method of reflecting the offset at the time of exposure is the same as in the above-described embodiment, and the offset OF of each of the measurement points 19 to 23 read from the memory by the focus control device 18 is used.
S ₁₉ ~OFS _23, the exposure area 31 throat areas (A to
It belongs to Q) and takes a value according to the following table.

[0346]

[Table 5] Using the read offsets OFS _{19 to} OFS ₂₃ ,
A value Z ₁₉ to which the surface position data z _{19 to} z ₂₃ of the exposure area is corrected
To calculate the Z _23.

That is, similarly to the above-mentioned Embodiment 2, Z ₁₉ = z ₁₉ -OFS ₁₉ Z ₂₀ = z ₂₀ -OFS ₂₀ Z ₂₁ = z ₂₁ -OFS ₂₁ Z ₂₂ = z ₂₂ -OFS ₂₂ Z ₂₃ = z ₂₃ -OFS ₂₃ The least square plane of the exposure area is obtained based on these new surface position data Z _{19 to} Z ₂₃ . A series of operations for transferring the reticle pattern is the same as in the above-described second embodiment, and a description thereof will not be repeated.

By using the method of this embodiment, even when the measurement point is in the boundary area of the pattern and there are 17 types of detection errors to be corrected, the detection error amount can be calculated using the “surface shape function constant method”. It is possible to decide. Moreover, the detection error (offset correction amount) can be determined with the same number of measurement shots as compared with the second embodiment, and the detection error (offset correction amount) is determined by one of many lots in each lot. As in the above-described embodiment, the reduction in throughput can be almost neglected by performing the process only for the second wafer and using the value obtained for the first wafer for the next wafer.

The procedure for determining the above detection error (offset correction amount) is briefly shown in the flowchart of FIG.

FIG. 34 is a schematic view of a main part of a third embodiment of the present invention.
FIG. 35 is an enlarged explanatory view of a part of FIG.

In FIGS. 34 and 35, the same elements as those shown in FIGS. 1 and 2 are denoted by the same reference numerals.

Next, part of the structure of this embodiment is shown in FIG.
A description will be given while overlapping with the first embodiment in FIG.

In FIG. 34, reference numeral 1 denotes a reduction projection optical system (projection lens system), and Ax denotes an optical axis of the projection optical system 1.
A reticle 1a has a circuit pattern formed on its surface, and is mounted on a reticle stage 1b. An illumination system 1c uniformly illuminates the surface of the reticle 1a. The projection optical system 1 reduces and projects the circuit pattern on the reticle 1a surface onto the wafer 2 surface. The wafer 2 is fixed on the wafer stage 3 by suction.

The wafer stage 3 has the optical axis A of the projection optical system 1.
A plane (xy plane) that is movable in two directions (x, y directions) in a plane (xy plane) orthogonal to the x direction (z direction) and the optical axis Ax, and is orthogonal to the optical axis Ax. The tilt can be adjusted with respect to.

Thus, the surface position of the wafer 2 placed on the surface of the wafer stage 3 can be adjusted arbitrarily. Reference numeral 4 denotes a stage control device, which controls driving of the wafer stage 3 based on a signal from a focus control device 18 described later.

[0356] SA is light irradiation means, SB is projection means, SC
Denotes photoelectric conversion means, which constitute a part of a surface position detecting device for detecting surface position information of the wafer 2 surface.
The projection means SB and the photoelectric conversion means SC use the detection means SB.
C.

In this embodiment, the circuit pattern on the reticle 1a surface is projected onto the wafer 2 by the projection optical system 1 using the surface position detecting device.
When projecting on the surface, the drive of the wafer stage 3 is controlled so that the exposure area on the surface of the wafer 2 is located within the allowable depth of focus of the projection optical system 1. Then, move the wafer stage 3 to X
The rectangular pattern area (shot) 39 is sequentially formed on the surface of the wafer 2 by sequentially moving on the −Y plane.

Next, each element of the surface position detecting device of this embodiment will be described. First, the light irradiating 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 comprises 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 a light beam from the light source 5 as a parallel light beam having a substantially uniform cross-sectional intensity distribution.

Reference numeral 7 denotes a prism-shaped slit member.
A pair of prisms are bonded together such that their slopes face each other, and the bonding surface has a plurality of openings (five pinholes) 71 to 75. Reference numeral 8 denotes a lens system, which is composed of both telecentric systems, and which transmits five independent light beams 71a to 75a passing through a plurality of pinholes 71 to 75 of the slit member 7 via a mirror 9 to five measurement points 19 on the wafer 2 surface. The light is guided at an incident angle substantially equal to ２３23.

At this time, a pinhole image having substantially the same size of the projected image is obtained. Further, the lens system 8 has an aperture stop 40 therein for adjusting the NA of each of the light beams 71a to 75a. In this embodiment, each of the above elements 5,
Light irradiation means SA is constituted by 6, 7, 8, and 9.

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

The five light beams 71a to 75a incident on the surface of the wafer 2 are perpendicular to the wafer 2 (the direction of the optical axis Ax).
35, a direction rotated by θ ° (θ = 22.5 °) in the XY plane from the X direction (shot arrangement direction) on the surface of the wafer 2 so as to be observed independently from each other as shown in FIG. More incident. Thereby, the same effect as in the first embodiment is obtained.

The five pin holes 7 of the slit member 7
1 to 75 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.
The size and shape of the pinholes 71 to 75 of the slit member 7 and the distance from the lens system 8 are set so that pinhole images having substantially the same size are formed on the surface of the wafer 2.

In this embodiment, each of the above elements 5, 6, 7,
A plurality of light beams (pinholes) are made incident on the surface of the wafer 2 by the light irradiating means SA composed of 8 and 9. In this embodiment, the number of measurement points on the surface of the wafer 2 is not limited to five but may be any number.

Next, a plurality of reflected light beams from the wafer 2
The projection unit SB that guides light onto the detection surface 17 of the photoelectric conversion unit SC as a position detection element made of a CD and forms an image will be described.

[0367] Reference numeral 11 denotes a light receiving lens, which is composed of both telecentric systems. Five reflected light beams from the surface of the wafer 2 are incident on the light receiving lens 11 via the mirror 10. The light receiving lens 11 forms a pinhole image at each position 24 to 28 with respect to each of the measurement points 19 to 23. 4
Reference numeral 1 denotes a stopper provided on the light receiving lens 11, which has the same effect as that of the first embodiment. The light fluxes from the pinhole images at the respective positions 24 to 28 are independently provided with five correction optical systems 1.
Light is incident on 2-16.

The correction optical systems 12 to 16 have their light axes parallel to each other since the light receiving lens 11 is a bi-telecentric system, and the pinhole images formed at the positions 24 to 28 are detected by the photoelectric conversion means SC. Re-imaging is performed on the surface 17 so that spot lights having the same size are formed. The photoelectric conversion means SC comprises a single two-dimensional CCD. In the present embodiment, the projection means SB is constituted by the above elements 10, 11, 12 to 16.

Each of the correction optical systems 12 to 16 has a plane-parallel plate having a predetermined thickness and a lens system.
It is coaxial or eccentric with respect to one optical axis. At this time, the parallel plane plate is used to correct the optical path length of each lens system. The lens system has a detection surface 17 at each of the measurement points 19 to 23.
It is provided to correct the above imaging magnification (projection magnification) so as to be substantially equal.

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 the present embodiment, a plurality of measurement points 19 to 23 having different distances from the light receiving lens 11 are provided by the photoelectric conversion means SC. When an image is formed on the detection surface 17, the imaging magnifications thereof are different from each other.

Therefore, in this embodiment, correction optical systems 12 to 16 are provided for each measurement point, and these measurement points 19 to 2 are provided.
The projection magnification on the detection surface 17 is set to be substantially equal (this correction optical system is described in detail in Japanese Patent Application No. 2-44236, filed by the present applicant).

At this time, each measurement point 19 on the wafer 2
The position of the pinhole image (spot light) incident on the detection surface 17 is changed depending on the surface positions (height direction, optical axis Ax direction) of No. to No. 23. The photoelectric conversion means SC detects a change in the position of the pinhole image at this time. Thus, in this embodiment, the surface position information of each of the measurement points 19 to 23 on the surface of the wafer 2 can be detected with the same accuracy.

Also, the measurement points 19 to 23 on the surface of the wafer 2 and the detection surface 17 of the photoelectric conversion means SC are conjugate to each other via the projection means SB (for each of the measurement points 19 to 23, (Correcting the fall). 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
The position of the pinhole image on the detection surface 17 changes in response to a local change in 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 of the measurement points 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 of each measurement point 19 to 23 from C (surface position information)
From this, position information on the surface of the wafer 2, that is, a position in the optical axis Ax direction (z direction), an inclination with respect to the XY plane, and the like are obtained. Then, a signal relating to the driving amount of the wafer stage 3 is input to the stage control device 4 so that the surface of the wafer 2 substantially matches the projection surface of the reticle 1a by the projection optical system 1.

The stage control device 4 drives and controls the wafer stage 3 in accordance with an input signal from the focus control means 18 and adjusts the position and orientation of the wafer 2.

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. Is input to the stage control device 4.

The stage controller 4 controls the position of the wafer stage 3 in the xy directions, and moves the wafer stage 3 in the z direction based on a signal input from the focus controller 18 via a signal line. Control and tilt control. This is the same in the first embodiment.

Next, a method of detecting the surface position of the pattern area 39 on the wafer 2 in this embodiment will be described.

As described above, the main factors of the detection error generated when the surface position of the wafer 2 is detected by the optical surface position detecting device shown in FIG. 34 are the light reflected on the resist surface of the wafer 2 and the substrate surface of the wafer 2. This is interference with reflected light. Since the influence of the interference varies depending on the pattern formed on the wafer substrate surface, the measurement error due to the interference is different for each of the plurality of measurement points 19 to 23.

In the reduction projection exposure apparatus as shown in FIG. 34, the pattern on the reticle 1a is sequentially transferred to each exposure area on the wafer 2 by the step & repeat method.
At this time, before performing the surface position detection and the pattern transfer, the alignment between the IC pattern already formed in the exposure area of the wafer 2 and the reticle pattern is performed.

The optical surface position detecting device is a projection lens system 1
, And the reticle 1 a is also positioned at a fixed position with respect to the projection lens system 1. Therefore, if the surface position is detected after the reticle pattern is aligned with the exposure area of the wafer 2, the measurement points 19 to 23
Approximately the same height position in each exposure region arranged on the wafer 2 is detected.

This means that the measurement points 19 to 23 detect the height positions of the portions having the same substrate (pattern) structure in each exposure area.

For this reason, the influence of the interference between the light reflected on the resist surface of the wafer 2 and the light reflected on the substrate surface of the wafer 2 on the detection result may be a value specific to each measurement point in the exposure area. As expected, the inventor has confirmed by experiment that an almost constant detection error actually occurs in each measurement.

By applying this phenomenon to surface position detection, a detection error at each measurement point is measured in advance, and the detection error at each measurement point is obtained from surface position data for each measurement point in the exposure area. How to correct and get accurate surface position information,
The present applicant has proposed in Japanese Patent Application Laid-Open No. 2-102518.

In this embodiment, the positional relationship between the exposure area 39 and the measurement points 19 to 23 of the surface position detecting device is determined by the rectangle connecting the measurement points 19, 20, 22, and 23 and the exposure area 39 as shown in FIG. It is assumed that the rectangles are almost equal.

At this time, the measurement point 21 is located substantially at the center of the exposure area 39, and intersects with the optical axis AX when measuring the surface position.
The surface position detecting device adjusts the mounting position in advance. The remaining measurement points 19, 20, 22, and 23 are located in the periphery of the exposure area 39, and the origin of the height measurement of the measurement points 19 to 23 is adjusted in advance so that they are on the same plane. The projection lens system 1 is made to substantially coincide with the best imaging plane.

At this time, depending on whether each of the measurement points 19 to 23 is on the pattern or on the boundary, the exposure area is divided into 17 areas A to Q as shown in FIG.

When each of the measurement points is on the boundary of the pattern, there are 12 possible positional relationships as shown in case-1 to case-12 in FIG. In FIG. 38, circles indicate measurement points, and hatched portions indicate a part of the measurement points on the pattern. The positional relationship between the measurement point and the pattern boundary is 12
The fact that the measurement points are present means that there are 12 types of detection errors (offset correction amounts) in the area where the measurement point is in the boundary area.

Here, considering the area on the pattern and the area on the boundary area for each of the measurement points 19 to 23, the following table is obtained.

[0391]

[Table 6] Further, in the area in the boundary area, the measurement points 19, 20, 2
As shown in the following table, Nos. 2 and 23 differ in the positional relationship between the measurement point and the pattern.

[0392]

[Table 7] Then, there are five types of detection errors in the area above the pattern, and 1 in the area in the boundary area with the pattern.
It is necessary to find two types, that is, a total of 17 types of detection errors.

In the third embodiment of the present invention, when the positional relationship between the measurement point and the pattern is, for example, in the arrangement shown in case-9 in FIG. 38, that is, the offset of the measurement point 23 in the O and P areas is as follows. Is determined.

The measurement points 21 for a plurality of exposure areas are set in advance.
Is determined as f (X, Y), and the measured value of the surface position of the measurement point 23 in the O and P areas is defined as z ^border ₉ X, Y). Time, surface shape function f
The coefficient of 21 is fixed and not subjected to the least squares method, and the least squares method is executed for the constant term c ^border ₉ .

That is, the equation of {[｛f (X, Y) + c ^border ₉ ｝ −z ^border ₉ (X, Y)] ² dXdY = 0 is solved, and the value of the constant term c ^border ₉ is changed to O, P This is an offset of the measurement point 23 in the area.

However, in this method, the xy coordinates of the measurement point 21 are (x, y), and the xy coordinates of the measurement point 23 are (x−δx,
y−δy), the surface position of the measurement point 23 is (δx, δ
y) Since the offset value is determined by extrapolating with a surface shape function representing the distant measurement point 21 and assuming that the difference from the extrapolated value is the measurement error caused by the influence of interference.
Change in topography between measurement points 21 and 23 (irregularities)
If there is, a measurement error may occur in the obtained offset value.

When the number of predetermined exposure regions for determining the offset value is large, the change in the topography is reduced to an amount that can be substantially ignored by the averaging effect. When the offset of the measurement point 23 in the O and P areas shown in case-9 is obtained, only two exposure areas for determining the offset value can be selected. It may be an error amount.

Therefore, in the present embodiment, even when there are irregularities in the exposure region such as the peripheral portion of the wafer, the influence of the local topography is improved by using the method described below.

First, an exposure area 3 for measuring a detection error
9 is determined in advance to four areas of K, M, O, and Q.

[0400] The reasons for selecting the four areas of K, M, O, and Q are as shown in the table below.

[0401]

[Table 8] This is because a total of 17 types of detection errors can be included, including 5 types of detection errors in the area above the pattern and 12 types of detection errors in the area in the boundary area with the pattern.

Further, the surface position detecting apparatus of this embodiment forms a plurality of pinhole images on the measuring points 19 to 23 almost equally, and provides a correction optical system for each measuring point to perform a plurality of measurement. The magnification, resolution, and accuracy for detecting the height position of each measurement point are substantially equal to each other.

Further, the NA is made substantially the same by the aperture stop 40 provided in the lens system 8, and the exit side is made telecentric by the lens system 8, so that each light beam 71a to 75
The light is incident on the measurement points 19 to 23 at a at substantially the same angle.

That is, the surface position detecting device of this embodiment is
The optical characteristics of the plurality of measurement points 19 to 23 are all equal. Therefore, it is possible to determine the detection error of the measurement points 19, 20, 22, and 23 using the measurement point 21.

First, the wafer stage 3 is moved, and the exposure area 39 in the K area on the wafer 2 is sent directly below the projection lens system 1 to align with the reticle pattern.
At this time, movement control of the wafer stage 3 is performed using an output signal from the laser interferometer. Then, the wafer 2 is fixed at a height position where the height position measurement value (in the optical axis AX direction) of the measurement point 21 becomes substantially zero.

Next, in the diagonal direction to the upper right of the exposure area 39 in the K area (indicated by a dashed line), (n + 1)
There are three measurement points. The measurement points necessarily include the positions of the measurement points 19, 21, and 23 shown in FIG. or,
(N + 1) measurement points arranged in a straight line are provided in a diagonal direction to the left (indicated by a chain line). This measurement point is shown in FIG.
Are necessarily included in the positions of the measurement points 20, 21, 22 shown in FIG.

Then, while the position in the direction of the optical axis AX is maintained at the above-mentioned height position, the wafer stage 3 is sequentially moved stepwise in the diagonal direction to the upper right, so that the wafer stage 3 is linearly arranged (n + 1).
At each position, the height position is measured using only the measurement point 21. The height position measurement value at this time, the _{^{F K r (m) (m}} = 1~n + 1).

Further, while the position in the direction of the optical axis AX is maintained at the above-described height, the wafer stage 3 is sequentially moved stepwise in the diagonally upward direction to the left, and at (n + 1) positions arranged in a straight line. , The height position is measured using only the measurement point 21.
The height position measurement value at this time, the _{^{F K l (m) (m}} = 1~n + 1). The height position F ^K _r (m), signal F ^K _l (m) corresponding to the measuring point 21 is input from the position detection element 17 to the focus controller 18, a memory - are stored in.

Similarly, each of the exposure areas 39 in the M, O, and Q areas on the wafer 2 is moved just below the projection lens system 1 by moving the wafer stage 3 and aligned with the reticle pattern. Shall be measured sequentially.
These height position measurement _{^{value, F K r (m) (}} m = 1~n + 1) F M l (m) (m = 1~n + 1) F O r (m) (m = 1~n + 1) F O _l (m) (m = 1 to n + 1) F ^Q _r (m) (m = 1 to n + 1) F ^Q _l (m) (m = 1 to n + 1)

This height position F ^M _r (m), F ^M _l (m), F
_{^{O r (m), F O}} l (m), F Q r (m), the signal of the measurement point 21 corresponding to F ^Q _l (m) is input from the position detection element 17 to the focus controller 18, a memory -Is stored.

Next, a method of obtaining a correction value for a measurement error will be described.

[0412] The exposure area 39 existing in the K area is shown in FIG.
It has a planar structure as shown in FIG. Reference numeral 91 denotes an area in which memories and the like are formed, and reference numeral 92 denotes a scribe line area in which bonding pads and the like are formed. It is assumed that the exposure region 39 is adjacent to the left, lower left, and lower sides of the exposure region 39 existing in the K area, but the wafer region 93 in which no pattern is formed is adjacent in the other surrounding directions. .

[0413] The cross-sectional structure in the diagonal direction to the upper right of the exposure region 39 existing in the K area has the structure shown in Fig. 39B. Area 9 where memory and the like are formed
Reference numeral 1 denotes a convex topography, a scribe line area 92 on which a bonding pad or the like is formed shows a concave topography, and a wafer area 93 on which no pattern is formed further shows a concave topography. . However, the surface of the exposed region 39 shows an almost flat topography with the resist layer 50 applied over the entire surface.

FIG. 39 (B) shows a case where there is no inclination with respect to the xy plane on which the wafer stage 3 moves.

FIG. 39 (C) shows a case where the exposure area 39 in the K area located at the periphery of the wafer has a warp on one side.

FIG. 40A shows the exposure area 3 in the K area.
Reference numeral 9 denotes a height position measurement value of the measurement point 21 when the wafer stage 3 is moved diagonally to the upper right while the position in the optical axis AX direction is maintained at the above-described height position. Solid line 60
Indicates a continuous height position measurement value of the measurement point 21 obtained when the wafer stage 3 is continuously moved.
The white circles indicate height position measurement values of the measurement points 21 at (n + 1) positions arranged in a straight line by sequentially moving the wafer stage 3 stepwise.

In the present configuration example, the reflectance at the surface of the resist layer 50 is increased by setting the incident angle φ of the measurement light in FIG. 34 to 70 degrees or more, and the height near the surface of the resist layer 50 is increased. As described above, the component transmitted through the resist layer and reflected on the wafer substrate is not zero, but the component reflected on the surface of the resist layer 50 and the component reflected on the wafer substrate are measured as described above. The interference causes a measurement error in the measured value of the height position.

[0418] As can be seen from the measurement values 61 to 65 in Fig. 40 (A), this measurement error is caused when the measurement point 21 is located at the boundary between the regions 91 and 92 or the regions 92 and 93 having different interference conditions. It becomes the most remarkable when doing. The measurement point 21 is
If they are located in the same region, the topography of the surface of the resist layer 50 will be measured almost faithfully. Therefore, this measurement error starts to occur when the measurement point 21 starts on an area where the interference conditions are different, and the range in which the measurement error occurs is the range where the measurement point 21 passes through the boundary, that is, on the wafer. It is within the size of the measurement point 21.

FIG. 40B shows the measurement point 2 when the exposure area 39 in the K area shown in FIG. 39C has a warp on one side.
1 is a height position measurement value. It is generally considered that warpage or the like is generated in the peripheral portion of the wafer, and the influence of the warp or the like is removed from the measured values in FIG.
After correcting the measured value to the state shown in FIG. 40A, the correction amount of the detection error must be determined.

As a result of many experiments, in FIG. 40 (B), the half cycle (one peak or valley of the measurement value) of the measurement error due to the influence of the interference observed in the measurement values 61 to 65 is at most a wafer. The diagonal length of the exposure area 39 (~ 30 m) which is equal to or less than the size of the upper measurement point 21 (~ 3 mm)
m), the height measurement value measured by moving the wafer stage is a “high-frequency component”, whereas the effect of wafer warpage is a “low-frequency component”. It was confirmed that approximation was possible at most with a cubic curve.

In this measurement, if the sampling interval of the (n + 1) measurement points is set to be equal to or smaller than the size of the measurement points 21 on the wafer, components such as warpage can be obtained with sufficient accuracy. It was confirmed that it could be approximated by a cubic curve.

The influence of wafer warpage and the like in FIG. 40B is obtained as follows.

That is, the cubic curve is defined as f _bend ^K _r (m) = am ³ + b m ² + cm + d. Here, a, b, c, and d are constants.

The least squares method is performed on the constants a to d of the cubic curve f _bend (m) using discrete measurement values F ^K _r (m).

That is, the calculation of {f _bend ^K _rm } −F ^K _r (m)) ² dm = 0 (m = 1 to n + 1) is performed to determine f _bend ^K _r (m).

The component f such as the sled determined in this way is
_{The bend} ^K _r (m) is shown in FIG.

Next, the measured value F in FIG.
^{For K} _r (m), a value excluding components such as sled, that is, F _pattern ^K _r (m) = F ^K _r (m) −f _bend ^K _r (m) (m = 1 to n + 1) calculate. Here, F _pattern ^K _r (m) is _calculated as shown in FIG.
The state is corrected to the state shown in FIG.

[0428] Hereinafter, similarly ^{_{∫ {f bend K l (m}} ) -F K l (m)} 2 dm = 0 ∫ {f bend M r (m) -F M r (m)} 2 dm = 0 ∫ ^{_{{f ben d M l (m}} ) -F M l (m)} 2 dm = 0 ∫ {f bend O r (m) -F O r (m)} 2 dm = 0 ∫ {f bend O l (m ) −F ^O _l (m)｝ ² dm = 0 ∫ ｛f _bend ^Q _r (m) −F ^Q _r (m)｝ ² dm = 0 ∫ ｛f _bend ^Q _l (m) −F ^Q _l (m) ^{) 2 dm = 0 (m =} 1~n + 1) is calculated, and after determining the coefficients of the cubic ^{_{curve, F pattern K l (m)}} = F K l (m) -f bend K l (m) ^{_{F pattern M r (m) =}} F M r (m) -f bend M r (m) F pattern M l (m) = F M l (m) -f ben d M l (m) F pattern O r ( _{^{m) = F O r (m}} ) -f bend O r (m) F pattern O l (m) = F O l (m) -f bend O l (m) F pattern Q r (m) = F Q r (m) −f _bend ^Q _r (m) F _pattern ^Q _l (m) = F ^Q _l (m) −f _{b end} ^Q _l (m) (m = 1 to n + 1) is calculated to remove the influence of warpage and the like.

First, with respect to the measurement point 21 at the center of the exposure area 39, “measurement points 19, 20, 22, 2 on the pattern”
The relative error amount PT ₁₉ of 3 " _{', PT 20', PT 22} ', PT
₂₃ 'and "Measurement points 19, 20, 22, 2 on the boundary area
3 of case-1 ~case-12 relative error amounts BD ₁ '~BD of "
_{Find 12} '.

[0430] That ^{_{is, PT 19 '= F pattern O}} r (n + 1) -F pattern O r ((n / 2) +1) PT 20' = F pattern Q l (1) -F pattern Q l (( n / 2) +1) PT ₂₂ ′ = F _pattern ^M _l (n + 1) −F _pattern ^M _l ((n / 2) +1) PT ₂₃ ′ = F _pattern ^K _r (1) −F _pattern ^K _r ((n / 2) +1), and BD ₁ ′ = F _pattern ^K ₁ (n + 1) −F _pattern ^K ₁ ((n / 2) +1) BD ₂ ′ = F _pattern ^O ₁ (1) − F _pattern ^O _l ((n / 2) +1) BD ₃ ′ = F _pattern ^M _r (n + 1) −F _pattern ^M _r ((n / 2) +1) BD ₄ ′ = F _pattern ^Q _r (1 ) −F _pattern ^Q _r ((n / 2) +1) BD ₅ ′ = F _pattern ^K _l (1) −F _pattern ^K _l ((n / 2) +1) BD ₆ ′ = F _pattern ^Q _r (n +1) −F _pattern ^Q _r ((n / 2) +1) BD ₇ ′ = F _pattern ^O _l (n + 1) −F _pattern ^O _l ((n / 2) +1) BD ₈ ′ = F _{pattern ^{M r (1) -F pattern M}} r ((n / 2) +1) BD 9 '= F pattern O r (1) -F pattern O r ((n / 2) +1) BD 10' = F pattern ^M _l (1) -F _pattern ^M _l ((n / 2) +1) BD ₁₁ ′ = F _pattern ^K _r (n + 1) −F _pattern ^K _r ((n / 2) +1) BD ₁₂ ′ = F _pattern ^Q _l (n + 1) −F _pattern ^Q _l ((n / 2) +1).

Here, assuming that the offset to be reflected on the measured value of the measuring point 21 is PT ₂₁ , the pattern is exposed on the wafer, obtained by an experiment, and the value C stored in the memory in advance is obtained.
If T, PT ₂₁ = CT is determined.

As described above, the peripheral measurement points 19, 20, and 2
The reliability of the entire offset value is improved by using an experimental value as an offset of the measurement point 21 which is a reference of the height position measurement of 2, 23.

Then, 17 types of offsets reflected on the measured values of the measuring points 19 to 23, ie, the offsets PT _{19 to} PT reflected on the “measuring points 19 to 23 on the pattern”.
T ₂₃ and “Measurement points 19, 20, 22, 2 on the boundary area
The offsets BD _{1 to} BD ₁₂ reflected as “case-1 to case-12 of No. 3” are as follows.

That is, PT ₁₉ = PT ₁₉ '+ CT PT ₂₀ = PT ₂₀ ' + CT PT ₂₁ = CT PT ₂₂ = PT ₂₂ '+ CT PT ₂₃ = PT ₂₃ ' + CT and BD ₁ = BD ₁ '+ CT BD ₂ = BD _{2 '+ CT BD 3 = BD} 3' + CT BD 4 = BD 4 '+ CT BD 5 = BD5' + CT BD 6 = BD 6 '+ CT BD 7 = BD 7' + CT BD 8 = BD 8 '+ CT BD 9 = BD 9' _{+ CT BD 10 = BD 10 '} + CT BD 11 = BD 11' + CT BD 12 = BD 12 '+ and CT.

The four offset PTs obtained here
_{19, PT 20, PT 22,} PT 23 and 12 offset B
D _{1 to} BD ₁₂ are stored in the memory.

Now that the offset to be reflected on each measurement point has been set, how to reflect the offset at the time of exposure will be described.

After the offset setting is completed, the first
The wafer stage 3 is moved so that the exposure area is directly below the projection lens system 1, and the first exposure area is aligned with the reticle pattern. After the alignment is completed, the surface positions of the five measurement points 19 to 23 in the first exposure area are detected by the surface position detection device, and the respective measurement points are detected in the focus control device 18 based on the output signal from the position detection element 17. Form surface position data.

[0438] The focus control unit 18, a memory - and designed to read the offset OFS ₁₉ ~OFS ₂₃ of each measuring point 19-23 from.

At this time, the offset OFS _{19 to be} read depends on which area (A to Q) in FIG. 37 the first exposure area belongs.
OFS ₂₃ takes a value according to the following table.

[0440]

[Table 9] In offset OFS ₁₉ ~OFS ₂₃ read, first surface position data of the five measurement points in the exposure area - calculating the value Z ₁₉ to Z ₂₃ with the corrected data z ₁₉ to z _23.

That is, Z ₁₉ = z ₁₉ -OFS ₁₉ Z ₂₀ = z ₂₀ -OFS ₂₀ Z ₂₁ = z ₂₁ -OFS ₂₁ Z ₂₂ = z ₂₂ -OFS ₂₂ Z ₂₃ = z ₂₃ -OFS ₂₃ . Focusing controller 18, the new surface position de - based on the data Z ₁₉ to Z _23, determining the least square plane of the first exposure region.

Further, the focus control device 18 inputs a command signal corresponding to the calculated result of the least square plane to the stage control device 4 so that the position and inclination of the wafer 2 on the wafer stage 3 in the direction of the optical axis AX are determined. It is adjusted (corrected). As a result, the first exposure area on the wafer 2 is positioned at the best image forming plane of the projection lens system 1. After the adjustment of the surface position, the first exposure area is exposed to transfer the reticle pattern.

When the exposure for the first exposure area is completed,
The wafer stage 3 is driven so that the second exposure area on the wafer 2 is directly below the projection lens system 1, and the same surface position detection, surface position adjustment, and exposure operation as described above are performed. After performing this series of operations until the exposure of the final exposure area is completed,
The wafer 2 is unloaded from the wafer stage 3.

As described above, the determination of the detection error (offset correction amount) at each measurement point on the wafer surface needs to be performed for each process in which a pattern to be formed is different.

However, it is sufficient that the frequency be performed once for each step. If the detection error (offset correction amount) is determined at the beginning of each step and the value is stored in the memory in the control device, Production can be performed with almost no reduction in the throughput of semiconductor chip production.

If four points in the K, M, O, and Q areas are measured in eleven points in the diagonal directions of upward and downward ascending, step movement and position adjustment between each shot are performed. If the time required for measurement is 0.4 seconds, the movement between measurement points in the diagonal direction, and the measurement time is 0.2 seconds, the time required for obtaining the detection error (offset correction amount) is about 2 seconds.
It's just under 0 seconds.

As described above, the detection error (offset correction amount) is determined only for the first wafer among many lots in each lot, and the value obtained for the first wafer is used for subsequent wafers. Then, the decrease in throughput can be almost ignored.

The measuring procedure in this case is briefly shown in the flowcharts of FIGS. 41 and 42.

In the fourth embodiment, the offset of the measurement point 21 is determined by experiment, and the remaining offset is determined based on this value. However, all offsets are automatically set as described below, and the offset setting is performed. It is also possible to improve workability.

The measurement error caused by the influence of the interference in the area K shown in FIG. 40A becomes remarkable when the measurement point is located at the boundary of the pattern as described above, and the measured value shown in FIG. Patterns below the measurement point as in areas 62 and 63 are areas 91 and 9
Even if it is the same at the boundary of 2, if the arrangement of the areas is reversed,
Even though the magnitude (absolute value) of the generated measurement error is the same, the sign is reversed.

Here, when considering (n + 1) height position measurement values, the measurement values 62 and 63 and 61 and 64 cancel each other, but the scribe line area 92 and the area 93 where the pattern is not formed. Measurement value 65 of the boundary region of
Only the remaining result.

Therefore, considering the average value of the (n + 1) height position measurement values in the K area shown in FIG. 40A, [1 / (n + 1)] · Σ ｛F ^K _r ( m)｝ = C _pattern ^K _r (m = 1 to n + 1) and converge to a constant value shown at 80 in FIG.

[0453] Next, in the position of the K areas and centrosymmetric on the wafer 2 in FIG. 43, a value obtained by correcting the components of the warp or the like of the right upstream of the measurement values in the O area "F _pattern ^O _r (m)" a Show.

Here, when considering (n + 1) height position measurement values, the measurement values 62 and 63 and 61 and 64 cancel each other out, and the scribe line area 92 and the area 93 where no pattern is formed are compared. Only the measured value 65 of the boundary region remains in the opposite sign to the K area shown in FIG.

Therefore, (n +
Given the average value of 1) of the height position measurement value, [1 / (n + 1 )] · Σ {F O r (m)) = C pattern O r and (m = 1 to n + 1) 43 Converges to a constant value indicated by 81.

Then, the following value becomes [1 / (n + 1)] Σ ｛{F _pattern ^K _r (m) + F _pattern ^O _r (m)} = C _pattern ^K _r + C _pattern ^O _r = 0, and the interference The measurement error caused by the influence of the above cancels out.

Similarly, between the measured values of the area at the centrally symmetric position on the wafer 2, [1 / (n + 1)] Σ ｛F _pattern ^K _l (m) + F _pattern ^O _l (m )｝ = C _pattern ^K _l + C _pattern ^O _l = 0 and [1 / (n + 1)] Σ ｛{F _pattern ^M _r (m) + F _pattern ^Q _r (m)} = C _pattern ^M _r + C _pattern ^Q _r = 0 and occurs at [1 / (n + 1) ] · Σ {F pattern M l (m) + F pattern Q l (m)} = C pattern M l + C pattern Q l = 0 , and the influence of interference Measurement errors will cancel each other out.

The applicant of the present invention has proposed a method of setting an offset of each measurement point using the sum of the measured values where the measurement errors cancel each other, in Japanese Patent Application Laid-Open No. 2-198130.
Using this method, the offset of each measurement point is set as follows.

[0459] That ^{_{is, PT 19 = F pattern O r}} (n + 1) - (C pattern K r + C pattern O r) PT 20 = F pattern Q l (1) - (C pattern M l + pattern Q l) PT ^{_{21 = F pattern K r ((}} n / 2) +1) - (C pattern K r + C pattern O r) PT 22 = F pattern M l (n + 1) - (C pattern M l + C pattern Q l) PT ₂₃ = F _pattern ^K _r (1)-(C _pattern ^K _r + C _pattern ^O _r ) and BD ₁ = F _pattern ^K _l (n + 1)-(C _pattern ^K _l + C _pattern ^O _l ) BD ₂ = F _pattern ^O _l (1) − (C _pattern ^K _l + C _pattern ^O _l ) BD ₃ = F _pattern ^M _r (n + 1) − (C _pattern ^M _r + C _pattern ^Q _r ) BD ₄ = F _pattern ^Q _r (1) − (C _pattern ^M _r + C _pattern ^Q _r ) BD ₅ = F _pattern ^K _l (1) − (C _pattern ^K _l + C _pattern ^O _l ) BD ₆ = F _pattern ^Q _r (n + 1) − (C _pattern ^M _r + C _pattern ^Q _r ) BD ₇ = F _pattern ^O _l (n + 1) − (C _pattern ^K _l + C _pattern ^{O _{l) BD 8 = F pattern M}} r (1) - (C pattern M r + C pattern Q r) BD 9 = F pattern O r (1) - (C pattern K r + C pattern O r) BD 10 = F pattern M _{l (1) - (C pattern} M l + C pattern Q l) BD 11 = F pattern K r (n + 1) - (C pattern K r + C pattern O r) BD 12 = F pattern Q l (n + 1) - and ^{_{(C pattern M l + C pattern}} Q l).

[0460] At this time, the offset of the measuring point ^{_{21, PT 21 = F pattern Q l}} ((n / 2) +1) - (C pattern M l + C pattern Q l C) or the like may be used.

The five offset PTs obtained here
_{19 ~PT 23,} and 12 stores offset BD ₁ ~BD ₁₂ into memory. The method of reflecting the offset at the time of exposure is as described above, and the description is omitted.

[0462] Also, when I'll set the offset as shown below, it is possible to reduce the influence of random errors due to _{^{F K r (m) ~F Q}} l noise and the like at the time of measurement of (m).

[0463] ^{_{Here, C pattern = (C pattern K}} r + C pattern O r + C pattern K l + C pattern O l + C pattern M r + C pattern Q r + C pattern M l + C pattern Q l) / 8 and, F _pattern ( (n / 2) +1) = ｛F _pattern ^K _r ((n / 2) +1) + F _pattern ^K _r ((n / 2) +1) + F _pattern ^M _r ((n / 2) +1) + F _pattern ^M _l ((n / 2) +1) + F _pattern ^O _r ((n / 2) +1) + F _pattern ^O _l ((n / 2) +1) + F _pattern ^Q _l ((n / 2) +1 ) + F _pattern ^Q _l ((n / 2) +1)｝ / 8.

Then, the offset of each measurement point is set as follows. ^{_{That, PT 19 = F pattern O r}} (n + 1) -C pattern PT 20 = F pattern Q l (1) -C pattern PT 21 = F pattern ((n / 2) +1) -C pattern PT 22 = _{^{Fpattern M l (n + 1)}} -Cpattern PT 23 = Fpattern K r (1) -Cpattern ^{_{and, BD 1 = F pattern K l}} (n + 1) -C pattern BD 2 = F pattern O l (1) -C _pattern BD ₃ = F _pattern ^M _r (n + 1) -C _pattern BD ₄ = F _pattern ^Q _r (1) -C _pattern BD ₅ = F _pattern ^K _l (1) -C _pattern BD ₆ = F _pattern ^Q _r ( _{n + 1) -C pattern BD 7} = F pattern O l (n + 1) -C pattern BD 8 = F pattern M r (1) -C pattern BD 9 = F pattern O r (1) -C pattern BD 10 = F _pattern ^M _l (1) -C _pattern BD ₁₁ = F _pattern ^K _r (n + 1) -C _pattern BD ₁₂ = F _pattern ^Q _l (n + 1) -C _pattern

The five offset PTs obtained here
_{19 ~PT 23,} and 12 stores offset BD ₁ ~BD ₁₂ into memory. The method of reflecting the offset at the time of exposure is as described above, and the description is omitted.

Next, an embodiment of a method of manufacturing a semiconductor device using an exposure apparatus that has performed the above-described surface position detecting method will be described. FIG. 44 shows a semiconductor device (IC or LSI)
2 shows a flow of manufacturing a semiconductor chip such as a liquid crystal panel or a CCD.

In step 1 (circuit design), the circuit of the semiconductor device is designed. Step 2 is a process for making a mask on the basis of the circuit pattern design. On the other hand, in step 3 (wafer manufacturing), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer. The next step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer created in step 4, and includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). including. In step 6 (inspection), an operation check test of the semiconductor device created in step 5 is performed.
An inspection such as a durability test is performed. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 45 shows a detailed flow of the wafer process. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. Step 1
In 5 (resist processing), a photosensitive agent is applied to the wafer. Step 16 (exposure) uses the above-described exposure apparatus to print and expose the circuit pattern of the mask onto the wafer.

In step 17 (developing), the exposed wafer is developed. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

By using the manufacturing method of this embodiment, it is possible to manufacture a highly integrated semiconductor device which has been conventionally difficult to manufacture.

[0471]

According to the present invention, in a system in which a focal plane position detecting mechanism for a plurality of measurement points is formed, even in a pattern area at a peripheral portion of a wafer, correction accuracy of a surface position equivalent to a pattern area at a central portion can be obtained. Therefore, the entire pattern area on the wafer can be located within the allowable depth, and the yield of the pattern area located on the peripheral portion of the wafer having a large warp is significantly improved. A position detection method and a projection exposure apparatus using the same can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic view of a main part of an embodiment of a projection exposure apparatus with a surface position detecting device.

FIG. 2 is an explanatory view of a part of FIG. 1;

FIG. 3 is an explanatory diagram of the pinhole (and a plurality of minute pinholes) in FIG. 1;

FIG. 4 is an explanatory view when a plurality of minute pinholes are projected on a wafer.

FIG. 5 is an explanatory diagram showing the behavior of each light flux of a plurality of minute pinholes on a wafer surface.

FIG. 6 is an explanatory diagram showing a plurality of minute pinhole images reflected by a wafer on the detection surface of FIG. 1;

FIG. 7 is an explanatory view showing a plurality of minute pinhole images reflected by a wafer on the detection surface of FIG. 1;

FIG. 8 is an explanatory diagram showing positions of a grid and a pattern area for topography measurement.

FIG. 9 is an explanatory diagram showing a topography of a pattern area.

FIG. 10 is a flowchart of an offset value (correction value) calculation method;

FIG. 11 is a flowchart showing an exposure operation including setting of an offset value.

FIG. 12 shows a two-dimensional CCD sensor 12 on a stage 3.
Figure with 0 placed

FIG. 13 is a diagram in which a light receiving element 131 having a pinhole 132 is arranged on a stage 3.

FIG. 14 is a flowchart for automatically setting an offset amount (correction amount).

FIG. 15 is a flowchart for automatically setting an offset amount (correction amount).

FIG. 16 is a flowchart for automatically setting an offset amount (correction amount).

FIG. 17 is a flowchart for automatically setting an offset amount (correction amount).

FIG. 18 is an explanatory diagram showing a topography of a pattern region.

FIG. 19 is a diagram showing a position of a grid and a pattern region for topography measurement.

FIG. 20 is a diagram showing a behavior of a light beam on a wafer surface in a conventional example.

FIG. 21 is a diagram showing an intensity distribution of a light beam reflected by a wafer on a position detecting element in a conventional example.

FIG. 22 is a schematic diagram of a main part of the first embodiment of the present invention.

FIG. 23 is an explanatory view of a part of FIG. 22;

FIG. 24 is a schematic diagram showing a positional relationship between an exposure area and a measurement point in the first embodiment.

FIG. 25 is a layout diagram in which an exposure region regularly formed on a wafer in the first embodiment is sectioned;

FIG. 26 is a diagram showing a positional relationship between a plurality of measurement points and an exposure area.

FIG. 27 is a flowchart of an offset value calculating method according to the first embodiment.

FIG. 28 is a flowchart of an offset value calculating method according to the first embodiment.

FIG. 29 is a flowchart of an offset value calculating method according to the first embodiment.

FIG. 30 is a schematic diagram showing a positional relationship between an exposure area and a measurement point in the second embodiment.

FIG. 31 is a layout diagram in which an exposure region regularly formed on a wafer in the second embodiment is sectioned;

FIG. 32 is a diagram showing a positional relationship between measurement points and pattern boundaries.

FIG. 33 is a flowchart of an offset value calculating method according to the second embodiment.

FIG. 34 is a schematic view of a main part of a third embodiment of the present invention.

FIG. 35 is an explanatory view of a part of FIG. 34;

FIG. 36 is a schematic diagram showing a positional relationship between an exposure area and a measurement point in the third embodiment.

FIG. 37 is a layout diagram in which an exposure region regularly formed on a wafer in the third embodiment is sectioned;

FIG. 38 is a diagram showing a positional relationship between a plurality of measurement points and an exposure area.

FIG. 39 is a schematic view showing the positional relationship between the exposure regions and the pattern structure.

FIG. 40 is a schematic diagram showing a measured value of a height position and a component of a sled with and without a sled.

FIG. 41 is a flowchart showing a measurement error measurement procedure;

FIG. 42 is a flowchart showing a measurement error measurement procedure;

FIG. 43 is a schematic diagram showing measured values of a height position in which a component of a sled is corrected.

FIG. 44 is a diagram of a semiconductor device manufacturing flow.

FIG. 45 is a diagram of a wafer process.

[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 means 5 light source 6 collimator lens 7 slit member 8 lens system 9, 10 mirror 12 to 16 correction optical system 17 position detection Element (CCD) 18 Focus control device 71 to 75 Pinhole 711 to 714 Micro pinhole 721 to 724 Micro pinhole 731 to 734 Micro pinhole 741 to 744 Micro pinhole 751 to 754 Micro pinhole

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/027 G03F 9/02

Claims (14)

(57) [Claims] When detecting a surface position of each of a plurality of pattern regions on a second object onto which a pattern on a first object is projected via a projection optical system in the optical axis direction of the projection optical system, A surface position detection method comprising: measuring a surface position in the optical axis direction at a plurality of measurement points, and correcting a measurement value at each measurement point with a correction value for each measurement point, wherein a predetermined one of the plurality of measurement points A plurality of correction values are set for the measurement points, and the correction values are selected from the plurality according to the positions of the respective pattern areas on the second object. 2. The apparatus according to claim 1, wherein the plurality of measurement points include a central point and a plurality of points around the center, and the predetermined measurement points include a plurality of points around the center. Surface position detection method. 3. When detecting the surface position of each pattern area, the plurality of surrounding measurement points are located at four corners of the pattern area to be detected or four measurement points located outside. The surface position detecting method according to claim 2, comprising: 4. A method according to claim 1, further comprising: setting a plurality of areas each including one or more of the pattern areas on the second object, and setting the correction value for the predetermined measurement point for each of the plurality of areas. The surface position detection method according to claim 1. 5. The surface position according to claim 1, wherein a surface position of the pattern area is detected using a result of correcting a measurement value at each of the measurement points with the correction value and a least square method. Detection method. 6. A method for manufacturing a semiconductor device, comprising using the surface position detecting method according to claim 1. 7. A projection exposure apparatus capable of performing focus control on each pattern area on a wafer using the surface position detection method according to claim 1. 8. A projection exposure apparatus for projecting a pattern on a reticle onto a plurality of pattern areas on a wafer via a projection optical system, wherein a surface position of each of the plurality of pattern areas in the optical axis direction is detected. Surface position detecting means, wherein the surface position detecting means measures a surface position in the optical axis direction of the projection optical system at a plurality of measurement points for each of the pattern regions, and measures a measured value at each measurement point Means for correcting with a correction value for each point, wherein the correction value for a predetermined measurement point of the plurality of measurement points is related to the predetermined measurement point in accordance with a position of the pattern area on the wafer. A projection exposure apparatus having a function of selecting from a plurality of correction values. 9. The method according to claim 8, wherein the plurality of measurement points include a central point and a plurality of points around the center, and the predetermined measurement points include four points around the center. Projection exposure equipment. 10. When detecting the surface position of each pattern area, the plurality of surrounding measurement points are located at four corners of the pattern area to be detected or four measurement points located outside. 10. The projection exposure apparatus according to claim 9, comprising: 11. A plurality of areas each including one or more of the pattern areas are set on the wafer, and the correction value for the predetermined measurement point is set for each of the plurality of areas. The projection exposure apparatus according to claim 8. 12. The projection exposure according to claim 8, wherein a surface position of the pattern area is detected using a result obtained by correcting a measurement value at each of the measurement points with the correction value and a least squares method. apparatus. 13. The surface position detecting means obliquely projects a plurality of light beams onto the wafer, re-projects a plurality of light beams reflected by the wafer onto a detection surface, and obtains the surface position on the wafer. 9. A plurality of oblique incidence type position detection systems for measuring a vertical position change of a pattern area to be detected as a position change of the plurality of light beams on the detection surface. The projection exposure apparatus according to claim 1. 14. A device comprising: a step of exposing a reticle pattern onto a wafer using the projection exposure apparatus according to claim 8; and a step of developing the exposed wafer. Production method.