KR100206631B1 - Projective explosing apparatus and a circut board explosing method - Google Patents

Abstract

[purpose]

Even if the height of the imaging surface of the projection optical system changes during the scanning exposure, the surface of the wafer is aligned with the imaging surface with high tracking accuracy continuously during the scanning exposure.

[Configuration]

The surface containing the image through the projection optical system 11 of the pattern in the illumination area 8 on the reticle 7 is defined as the first reference plane 62, the inclination angle θxp, etc. of the reference plane 62 is obtained, and the reticle 7 is obtained. In the case of scanning in the X direction, the inclined angle θ of the reference plane 65 is obtained by setting the upper surface that connects the attack image on the wafer 12 side of the center point of the illumination region 8 as the second reference plane 65. In the scanning exposure yarn, the inclination angle of the field of view field 13 of the wafer 12 is adjusted to the first reference plane 62, and the focal position of the wafer 12 is adjusted to the second reference plane 65.

Description

Exposure Method of Projection Exposure Apparatus and Circuit Board

1 is a block diagram showing a projection exposure apparatus of a step-and-scan method in which an embodiment of the present invention is applied.

FIG. 2 is a plan view showing a distribution of measurement points of focal positions on the wafer 12 of FIG.

FIG. 3 shows the light transmission slit plate 28 in FIG.

FIG. 4 is a diagram showing the vibrating slit plate 31 in FIG.

FIG. 5 shows the slit plate 31 in FIG. Fig. 5 is a configuration diagram showing the photoelectric detector 33 and signal processing system 34 in Fig. 5.

FIG. 6 is a configuration diagram in which a portion showing a configuration example of the actuator 16A in FIG. 1 is taken in cross section. FIG.

FIG. 7 is a configuration diagram including a partial perspective view showing the woofer 12 focus leveling mechanism in FIG. 1 and a control system thereof.

8A is a conceptual diagram showing a first reference plane 62 for the field of view field 13, and FIG. 8B is a conceptual diagram showing a second reference plane 65 for the exposure field on the wafer 12. FIG.

9 is a view for the inclination and height of the plane determined at the tips of the three actuators 16A to 16C.

FIG. 10 is a configuration diagram including a partial perspective view showing a focusing and leveling mechanism of the wafer 12 and its control system in FIG.

FIG. 11A is a conceptual diagram showing a state where the detection area of the multipoint AF sensor 25 enters onto the wafer 12 from the outside of the waiter 12, and FIG. 11B is a wafer 12 of the detection area of the multipoint AF sensor 25. FIG. A conceptual diagram showing a state coming out of the wafer 12 from an area on the top face), and FIG. 11C is a conceptual diagram showing a case where a part of the surface of the wafer 12 is in a groove shape.

12 is a configuration diagram of main parts when an AF sensor for detecting a wafer on a wafer other than the multi-point AF sensor 25 is provided in advance.

13 is an explanatory diagram of an example of a method of determining a wafer model when the wafer surface is deformed.

FIG. 14 is a block diagram schematically illustrating the projection exposure apparatus shown in FIGS. 1 and 10. FIG.

* Explanation of symbols for main parts of the drawings

12: wafer 16A: actuator

[Industrial Use]

The present invention relates to, for example, a projection exposure apparatus used in a photolithography process for manufacturing a semiconductor device (LSI, etc.), an imaging device (CCD, etc.), a liquid crystal display device (LCD, etc.) or a thin film magnetic head. In particular, the present invention relates to a scanning exposure type projection exposure apparatus such as a so-called step-and-scan method that sequentially transfers a mask pattern onto a photosensitive substrate by scanning the mask and the photosensitive substrate in synchronization with the projection optical system.

Conventional Technology

Conventionally, when manufacturing a semiconductor device or the like using photolithography technology, a step-end of exposing a reticle pattern as a mask to each shot region on a wafer (or glass substrate, etc.) to which a photoresist is applied as a photosensitive substrate is applied through a projection optical system. A repeating projection device (stepper or the like) is used. On the other hand, in recent years, a single chip such as a semiconductor element tends to be enlarged, and it is required to expose a larger area pattern onto a wafer. Thus, a projection exposure apparatus of a scanning exposure method has been developed in which the reticle and the wafer are synchronously scanned with respect to the projection optical system so that exposure to a shot area wider than the favorable exposure field of the projection optical system is possible.

BACKGROUND ART As a projection exposure apparatus of a scanning exposure method, an aligner is conventionally known in which an entire reticle pattern is projected and sequentially exposed on the entire surface of one photosensitive substrate in the same multiple. In addition, the recently developed projection exposure apparatus is a step-and-scan method in which exposure to each shot region on a wafer is carried out in a reduced projection and scanning exposure method, and a movement between the shot regions is performed in a stepping manner.

In general, in the projection exposure apparatus, a large numerical aperture (NA) and a shallow depth of focus are used for the projection optical system, and a mechanism for fitting the surface of the wafer to the image plane of the projection optical system is necessary to transfer fine circuit patterns with high resolution. Do.

Thus, in the conventional exposure type exposure apparatus, for example, a tult sensor (leveling sensor) for measuring the square of the wafer surface with respect to the guide surface (traveling surface) of the wafer stage is implemented, and the projection optical system is referred to based on the guide surface. The inclination angle of the imaging surface is measured beforehand. The wafer surface is aligned parallel to the stool surface by the servo method so that the measured value by the tilt sensor converges on this tilting operation. This tilt angle control (auto leveling control) is used in combination with the so-called auto focus control that adjusts the height (focus position) of the wafer surface to the image plane position of the projection optical system, so that the entire depth region of the wafer is focused on the image plane. It fits in the range of. Also in the projection exposure apparatus of the scanning exposure method, the wafer surface is conventionally fitted to the image forming surface by the control method almost the same as that of the package exposure method.

In addition, the scanning exposure method, projects the (referred to below, ^[crude _Fields) projected area of the slit on the wafer through the projection optical system, the part pattern of the reticle. The large area in which the pattern image of the entire reticle is projected on this Joy field is sequentially called ^" Joy Field _" (corresponding to the short area).

In the conventional scanning exposure method, in particular, the step-and-scan projection exposure apparatus having a reduced magnification, since the reticle and the wafer are scanned independently of the projection optical system, the running surface of the reticle and the running concept of the wafer are set independently of each other. In addition, since the running surface of the reticle and the pattern forming surface of the reticle cannot be strictly parallel, the height of the imaging surface (the upper surface of the pattern of the reticle) of the projection optical system may change gradually depending on the scanning position of the reticle. As described above, when the height of the imaging surface gradually changes, a tracking error occurs due to the response speed of the autofocus control, and the surface of the exposure field (short region) of the wafer partially deviates from the depth of focus with respect to the imaging surface. Do not worry.

In addition, since the AF sensor and the tilt sensor detect the focal position and the inclination angle of the surface of the projection area (the slit-shaped field of view field in the scanning exposure method) which are the exposure targets of the wafer, the detection range is usually almost the projection area (or Joya field) was set inside. Therefore, the conventional squin focuses only on the exposure column to each projection area on the wafer and performs rebalancing control. When moving to the next projection area, the Z stage and the tilt stage are fixed by turning off the control of one focusing leveling. Then, positioning to the next projection area (or scanning start position) is performed, and the focusing and leveling control is started again. This is because the whole movement path to the next projection area (or the scanning start position) is not necessarily entered into the detectable area of each sensor, and it is difficult to continue focusing or leveling control outside the detectable area. In this way, if the surface of the wafer is inclined with respect to the stage guide surface in such a manner that the control of focusing and leveling is turned off during the movement, the focal position of the wafer surface is greatly changed before and after the movement. In this case, the next time the focusing and leveling control is started in the field of illumination to be exposed, the amount of pull, which is the difference between the defocus amount and the inclination angle, becomes large, and the adjustment time until the amount falls within a predetermined allowable value and stabilizes (draw time) ) Was long and there was an inconvenience that the efficiency (the number of wafers processed per unit time) of the exposure process was reduced as a crystal.

In particular, in the step-and-scan projection exposure apparatus, focusing and leveling are continuously performed on the wafer surface moving during scanning exposure. Therefore, the focusing and leveling operations are scattered in the case where there is a groove-shaped region (e.g., a so-called street line indicating a chip boundary in a semiconductor chip) that is not originally expected to be focused and leveled on the wafer surface. There was a discomfort that worsened or increased adjustment time.

Summary of the Invention

In view of the above, an object of the present invention is to provide a projection concentrating device which can align a wafer surface with a stool surface continuously with high tracking accuracy during scanning exposure even if the height of an image plane of the projection optical system changes during scanning exposure. .

In addition, the amount of deviation in the focus position when starting focusing after passing through a region in which there is a gap in the region where the focusing of the wafer surface is not subject to control or immediately after entering the region from outside the wafer is reduced. It is an object of the present invention to provide an exposure apparatus capable of shortening a drawing time (adjustment time) until the drawing is completed.

The projection apparatus according to the present invention illuminates a mask 7 on which a pattern for transfer is formed, and a predetermined exposure area (a field of illumination field) on a photosensitive stone substrate 12 through a projection optical system 11 on an image of a part of the pattern of the mask. The inclination angle and projection of the predetermined exposure area 13 on the substrate 12 in the projection exposure apparatus for transferring the image of the pattern of the mask 7 in the state projected on the surface 13 in order to the exposure field on the substrate 12. The first reference plane which determines the position detection sensor 25 which detects the focus position of the optical axis direction of the optical system 11, and the inclination angle detected by this position detection sensor by the projection image by the projection optical system 11 of the mask 7. Focusing angle controllers 16A to 16C 20 which control the inclination angle of the substrate 12 to match the inclination angle of the 62 and the focal position detected by the position detection sensor 25 are used as the running surface 10a of the mask 7. ) Inclination angle (0x) in the scanning direction and inclination angle of the mask 7 Focus position control units 16A to 16C and 20 are provided to control the optical axis direction positions on the substrate 12 so as to match the focal position of the second reference plane 65 determined according to the above.

In other words, in the projection exposure apparatus of this invention, the 1st reference surface 62 with respect to the projection area | region (field of illumination field) of the pann of a mask part, and the 2nd reference plane with respect to the exposure field on the board | substrate 12 obtained as a result of a scanning exposure. The 65 reference is controlled and the inclination angle of the board | substrate 12 is controlled based on the focal position of the 1st reference surface 65.

In this case, the inclination angle of the first reference plane 62 and the change state of the focus position of the second reference plane 65 are measured in advance and stored in the inclination angle controllers 16A to 16C and 20 and the focus position controllers 16A to 16C and 20, respectively. It is preferable that it is done.

This principle of the present invention will be described with reference to FIG. 8, which shows the main part of an embodiment of the present invention. In FIG. 8A, the two-dimensional inclination angles of the traveling surfaces (guide surfaces) 17a of the stage systems 14 15X and 15Y for scanning the substrate 12 are referred to as reference values (0, 0). The two-dimensional inclination angle indicates, for example, the inclination angles around the Y-axis and the X-axis, which are Cartesian coordinate systems in a plane perpendicular to the optical axis of the projection optical system 11. Then, the image plane of the field of view field 13, which is a projection image of a part of the mask 8, is set as the first reference plane 62, and the inclination angle of the first reference plane 62 with respect to the traveling surface 17a is set to (? Xp, θyp). The inclination angle of the surface of the substrate 12 is controlled by the inclination angle control unit with the inclination angles? Xp and? Yp of the first reference plane as the target values. As a result, the flat surface of the substrate 12 is set parallel to the first reference surface 62.

In this state, when the mask 7 and the substrate 12 are scanned, the first reference surface 62 is inclined with respect to the running surface 17a, so that the substrate 12 is in accordance with the position of the substrate 12 in the scanning direction. The position (height) in the Z direction changes. When the substrate 12 has the scanning direction in the + Y direction and the position of the substrate 12 is at the position XO shown in FIG. 8A, the z-direction of the zO substrate 12 is shown in FIG. 8B. When the position in the z direction when the position X is changed to zA is set as zA, the following relationship is approximately established.

zA = (X-XO) θxp + 20 .... Equation 1

Here, in order to consider the influence by the scanning of the mask 7, it is assumed that the forming surface of the pattern of the mask 7 is inclined at a predetermined angle in the scanning direction with respect to the running surface 10a of the mask 7. As a result, when the mask 7 is viewed in the X direction as shown in FIG. 8B, the position of the image plane at the center of the field of view is formed at an inclination angle (inclination angle around the Y axis) Θx with respect to the scanning direction. It moves along the second reference plane 65. In addition, the projection magnification from the mask of the projection optical system 11 to the substrate is set to x0 and x in the X-direction position of the mask 7 in the states of FIGS. 8A and 8B, respectively, where β (β is, for example, 1 / 4, 1/5, etc.), the following relationship holds when the projection optical system 11 projects all inverted images.

X-X0 = β (x-x0) ... Equation 2

In addition, since the inclination angle of the second reference plane 65 is the focal position when the θx plate 12 is at the position XO shown in FIG. 8A, the focal position at the center of the irradiation field in the state of FIG. 8B is expressed by the following equation. The focus position zB is displayed.

zB = (X-X0) Θx + z0 ... Equation 3

Therefore, the focusing control (auto focus control) which promotes the board | substrate 12 to az direction can be performed aiming at this focal position zB. However, in practice, the focal position of the substrate 12 changes to the focal position zA shown in Equation 1 in accordance with the square of the first reference plane 62, so that the defocus amount δz represented by the following equation occurs.

δz = 2B-za = (X-X0) Θx-θxp) ... equation

Therefore, the actual focusing control can be performed so that the defocus amount δz in Expression 4 is zero. In addition, the inclination angle 0xp of the first reference plane 62 and the inclination angle Θx of the second reference plane 65 may be obtained by, for example, a test print and stored. As a result, it is possible to change the position of the z direction of the board | substrate 12 according to the projection surface as the whole mask 7, while fitting the inclination angle of the board | substrate 12 with the image plane of the projection image in the field of view of the mask 7. do.

In addition, the projection exposure apparatus according to the present invention includes a projection optical system 11 for projecting the pattern on the mask 7 onto the photosensitive substrate 12 and a substrate resin 14 for moving the substrate to the image plane side of the projection optical system 11. An exposure apparatus having an image of 15x, 15y, and 17 and dispensing the pattern of the mask 7 onto the substrate 12 positioned with this substrate stage, in the direction of the optical axis of the projection optical system 11 of the substrate 12. A focal position detection sensor 43 for detecting the focal position and a stage focal position detecting sensor 43 for detecting the height in the optical axis direction of the projection optical system 11 of the substrate stages 14, 15x, 15y and 17; On the surface state of the substrate 12 at the second focal position determined based on the first focal position detected by the substrate focal position detection sensor 25 and the height detected by the stage focal position detection sensor 43. Focus position clause to select one focus position along Is provided with a portion (154, 155) and the focus position control section (16A, to about 16C) for controlling the focal position of the substrate 12 depending on the focal position selected by the focal position switching.

In this case, for example, as shown in FIG. 11A, when passing through the outer region of the substrate 12 during the movement to the next projection region, the focus position detection for the substrate may not be carried out. Pseudo-focusing control using a pseudo focusing position using a second focusing position determined by adding, for example, a predetermined offset to the height of the substrate stage detected by the stage focusing position detecting sensor 43 Is done. Thereby, the defocus amount at the time of focusing the board | substrate focal position using the detection sensor 25 can be reduced.

Moreover, the projection exposure apparatus of this invention projects the projection optical system 11 and the board | substrate 12 which project a part of the pattern of the pattern on the mask 7 to the predetermined exposure area | region 13 on the photosensitive board | substrate 12, and a projection optical system ( Pattern of the mask 7 by having the substrate stages 14, 15x, 15y, and 17 moving on the upper surface side of 11) and scanning the mask 7 and the substrate 12 in synchronization with the projection optical system 11. A scanning type exposure apparatus which sequentially transfers an image onto a substrate 12, comprising: a substrate focal position detection sensor 25 for detecting a focal position in the optical axis direction of the projection optical system 11 of the substrate 12; 16A of stage position detection sensors which detect the height of the optical-axis direction of the projection optical system 11 of this board | substrate stage, and the memory | storage part which stores the step information as design data of the surface of the board | substrate 12. 155, the first focal position Z detected by the focal position detection sensor 25 for the substrate, and One according to the step information of the substrate 12 stored in the storage unit 155 at the second focal position Z 'determined based on the height PZ detected by the focal position detection sensor 16A for tape. And a focus position control section 16A to 16C for controlling the focus position of the substrate 12 in accordance with the focus position selected by the focus position switching section.

That is, this projection exposure apparatus is a projection exposure apparatus of a scanning exposure method, and is formed in the grooves 68, such as a street line, in one projection area | region on the board | substrate 12 as shown, for example in FIG. 11C. In this case, if the focusing is always performed using the focal position detection sensor 25 for the substrate in the projection area, the tracking accuracy is weakened immediately after the groove 68. Thus, in the region including the groove 68, the height detected by the focusing position detecting sensor 16A for the stage is also focused based on, for example, the second focusing position determined by adding a predetermined offset. The following followability becomes favorable.

In these cases, it is preferable to provide an arithmetic unit 158 that predicts the second focal position z 'based on the height PZ detected by the stage focal position detection sensor 43 and a predetermined model. The predetermined model means step information in the projection area of the substrate 12, for example.

EXAMPLE

EMBODIMENT OF THE INVENTION Hereinafter, the Example of the projection exposure apparatus by this invention is described with reference to drawings. This embodiment applies the present invention to a projection exposure apparatus of a step end scan method.

FIG. 1 shows the projection exposure apparatus of the present embodiment, and in this FIG. 1, the first relay lens 2 and the blind line are exposed to the illumination light IL for exposure in the tube system 1 including a light source, an optical integrator, and the like. Slit-shaped illumination area of the pattern formation surface (lower surface) of the reticle 7 with uniform illuminance distribution through the variable field aperture) (3), the second relay lens (4), the mirror (5) and the main condenser lens (6). Illuminate (8). The bezel surface of the reticle blind 3 is substantially parallel to the reticle 7 patch shape surface, and the position and shape of the illumination illumination region 8 are set by the position and shape of the opening of the reticle blind 3.

The image through the optical system 11 of the pattern in the illumination area 8 on the reticle 7 is projected and exposed into the sullet-shaped coarse field field 130 on the photoresist coated wafer 12. Here, on the optical axis of the projection optical system 11 Take the Z-axis in parallel and take the X-axis to the ground in Fig. 1 and the X-axis parallel to the ground in Fig. 1 in a two-dimensional plane perpendicular to its optical axis.The reticle 7 is held on the reticle stage 9 and reticle stage 9 is driven by, for example, a linear motor in the scanning direction X on the reticle base 10. By means of a moving mirror 18 on the reticle stage 9 and an external laser interferometer 19. The X-axis of the reticle 7 is measured and this X-coordinate is supplied to the subject system 20 that controls the operation of the entire apparatus.The main control system 20 supplies the reticle stage drive system 21 and the reticle stage 9 to each other. Of the reticle 7 through its position and movement speed Control is performed.

The wafer 12, on the other hand, is held on the Z tilt stage 14 through a waiter holder, not shown. The Z tilt stage 14 is mounted on the Y stage 15Y via actuators 16A to 16C that are free to move in three Z directions. The Y stage 15Y is arranged to be moved on the stage 15X in the Y direction by, for example, a screw thread method. The X stage 15X is arranged to move in the X direction on the apparatus base 17 by, for example, a screw thread method. By stretching three actuators 16A to 16C in parallel, adjustment of the position (focal position) of the Z tilt scale 14 in the Z direction is performed, and the amount of expansion and contraction of the three actuators 16A to 16C is adjusted. By adjusting them individually, the inclination angles around the X and Y axes of the Z tilt stage 14 are adjusted.

In addition, the X coordinate of the wafer 12 is always monitored by the laser interferometer 23X of the movable mirror 22X for the X-axis fixed to the upper end of the Z tilt resin 14, and the movement rule 22Y for the Y-axis (see The Y coordinate of the wafer 12 is always monitored and supplied to the detected X coordinate Y coordinate main control system 20 by the external laser interferometer 23Y.

Here, a configuration example of the actuators 16A to 16C will be described.

FIG. 6 is a sectional view of the actuator 16A. In FIG. 6, the drive mechanism housing well 40 is fixed on the Y stage 15X of FIG. 1, and the screw 41 in the drive mechanism housing 40 is fixed. The rotation is freely received and the rotary encoder 43 for detecting the rotation angle is connected to the left end of the sending screw 41 through the coupling 42, and the rotary motor is connected to the right end of the sending screw 41 through the coupling 44. 45 is connected. In addition, the nut 39 is fitted to the sending screw 41 and the sloped portion 36A whose upper end is inclined through the support 38 is fixed to the nut 39, and the rotating body (36A) is fixed to the upper end of the sloped portion 36A. 36B) is in contact. The rotating body 36B is embedded in the Z ult stage 14 of FIG. 1 so that rotation can not move freely and transversely.

Moreover, the slope part 36A is supported so that the slope part 36A can move to the direction parallel to the sending screw 41 along the ridge guide 37. As shown in FIG. In this case, a control signal indicating the burn speed in the wafer stage control system 24 of FIG. 1 is supplied to the rotary motor 45, and the rotary motor 45 rotates the screw 41 sent at the indicated drive speed (angular speed). Let's do it. As a result, the nut 39 moves in the X direction along the screw thread 41, and the slope 36A also moves along the screw thread 41. As shown in FIG. Therefore, the rotating agent 36B which contacts the upper end of the slope part 36A rotates and displaces in the up-down direction (Z direction) with respect to the drive mechanism housing | casing 40. As shown in FIG. Further, by measuring the rotational angular velocity of the screw (41) by means of the rotary encoder 43, the moving speed in the downward direction of the rotating body 36B is detected. It is the same structure as other actuator 16B, 16C.

In addition, the actuators 16A to 16C may be configured using, for example, a laminated piezoelectric element (piezo element) or the like in addition to the method of using a rotary motor as shown in FIG. Thus, when using the drive element which displaces linearly as actuator 16A-16C, as an encoder for detecting the position of Z direction, a lanania encoder, such as an optical or a capacitive stone, can also be used.

Returning to FIG. 1, the main control system 20 controls the operations of the X stage 15X, Y stage 15Y, and Z tilt stage 14 through the wafer stage driver 24 based on the supplied coordinates. For example, in the case of performing exposure by the scanning exposure method, the projection optical system 11 projects the inverted image at a projection magnification β (β is for example 1/4) and the reticle 7 through the reticle stage 9. ), Through the X stage 15X, the wafer 12 through the X stage 15X in synchronization with the measurement of the velocity VR in the + X direction (or -Y direction) with respect to the illumination region 8. Or scan at the speed VW (= β VR) in the + Y direction.

Next, a configuration of a multi-point focus position detector (hereinafter referred to as ^[ multi-point AF sensor _] 25) for detecting a position (focus position) in the Z direction on the surface of the wafer 12 will be described. Non-photosensitive detection light is irradiated to the photoresist from the light source 26 in 25. The detection light illuminates a plurality of slits in the optical tactical slit plate 28 through the cone sensor lens 27 and differs in their slit. Fifteen of the field of view field 13 on the oblique wafer 12 and the front and rear areas 35A and 35B (see FIG. 2) before and after the oblique wafer 12 with respect to the optical axis of the projection optical system 11 through the objective lens 29 Projected to measurement points P11 to P51.

2 shows the arrangement of those measurement points P11 to P51 on the wafer 12. In this FIG. 2, the area | regions 35A and 35B which read first are set to the + X direction and the -X direction side with respect to the slit-shaped illumination field field 13, respectively. The measurement points P210 of three rows by three columns are set in the field of view 13, and three measurement points P51 to P53 are set in the area 35A to be read first. From the information of the focal positions at nine measurement points in the drawing, the average focal position and the inclination angle in the field of view field 13 are obtained, and if necessary, the focal position at three measurement points in the area 35A (or 35B) to be read first. Using the information, the level difference of the surface of the wafer 12 is corrected.

In FIG. 1, the reflected light at these measurement points is condensed on the vibration slit plate 31 through the condensing lens 30, and the sullet image projected to those measurement points on the vibration slit plate 31 is re-imaged. The vibrating slit plate 31 vibrates in a predetermined direction by an exciter 32 driven by the drive signal DS in the main control system 20. Whether light passing through a plurality of slits of the vibrating slit plate 31 is photoelectrically converted by the plurality of photoelectric conversion elements on the photoelectric detector 33 and supplied to these photoelectric conversion signal processor 34 and signal processed, 20 is supplied.

FIG. 3 shows the light transmission slit plate 28 in FIG. 1, and now in FIG. 3, the light transmission slit plate 28 has slits at positions corresponding to the on-wafer measurement points P11 to P53 in FIG. (28 11) to (28 53) are formed. On the vibrating slit plate 31 of FIG. 1, as shown in FIG. 4, the slits 31 11 to 32 53 are respectively located at positions corresponding to the wafer-shaped measurement points P11 to P53 of FIG. The vibration slit plate 31 is vibrated in the measurement direction orthogonal to the longitudinal direction of each slit by the exciter 32.

Next, FIG. 5 shows the photoelectric detector 33 and the signal processing system 34 in FIG. In FIG. 5, the first row of photoelectric conversion elements 33 11 to 33 13 on the photoelectric detector 33 is reflected at the measurement points P11 to P13 in FIG. ), The transmitted light of the corresponding slit is incident. The second to fourth photoelectric conversion substrates 33 21 to 33 43 on the photoelectric detector 33 are respectively reflected at the measurement points P21 to P43 in FIG. 2 and also in the vibrating slit plate 31. Light passing through the corresponding slit is incident. The fifth row of photoelectric conversion elements 33 51 to 33 53 on the photodetector 33 are respectively reflected at the measurement points P51 to P53 in FIG. 2 and corresponding slits in the oscillating slit plate 31. Light passing through is incident. The detection signals at the photoelectric conversion elements 33 11 to 33 53 are supplied to the synchronous rectifiers 47 11 to 47 53 through the heavy amplifiers 46 11 to 46 53. The synchronous rectifiers 47 11 to 47 53 each focus in a predetermined range almost in proportion to the focal position of the corresponding measurement point by synchronous rectifying the input detection signal using the drive signal DS for the exciter 32. Generate a signal. In this embodiment, the focus signals output from the synchronous rectifiers 47 11 to 47 53 are respectively measured in the projection optical system in the state in which the reticle 7 is stopped at the center of the scanning direction, for example, in FIG. The calibration is carried out so that it becomes 0 when it fits in the formed (best focus surface) of (11).

The focus signals output from the synchronous rectifiers 47 11 to 47 53 are supplied in parallel to the multiplexer 48 and the multiplexer 48 is switched in the microprocessor (WPU) 50 in the main control system 20. The focus signal selected in sequence from the focus signal supplied in synchronization with the signal is supplied to the analog / digital (A / D) converter 49, and the digital focus signal output from the A / D converter 49 is in turn the main control system ( 20 is stored in the memory 51 in FIG.

FIG. 7 shows the drive system in the three actuators 16A to 16C in FIG. In the main control system 20 of FIG. 7, the digital positions representing the focal positions at the measurement points P11 to P53 of FIG. 2 are respectively located in the respective addresses 51 11 to 51 53 of the memory 51. The focus signal is stored. In addition, these focus signals are rewritten in order of predetermined sampling periods. Among these addresses, the focus signals read out from addresses 51 21 to 51 43 corresponding to the measurement points in the field of view field 13 in FIG. 2 are supplied to the least-squares calculation unit 52 in parallel. The least-squares calculation unit 52 matches the surface of the field-of-field 13 with the least square method based on nine focus signals corresponding to the nine measurement points P21 to P43 in the field-of-field 13. The plane is determined and the inclination angle 0 x around the focal position (Z coordinate) Z, Y around the predetermined plane center and the inclination angle 0y around the X axis are obtained. These inclination angles [theta] x inclination angle [theta] y and the focal position Z are supplied to the subtracting portions 54A and 54C.

Further, the signals read from addresses 51 11 to 51 13 and 51 51 to 51 53 in the memory 51, i.e., correspond to the points in the first reading areas 35A and 35B in FIG. The focus signal is supplied to the correction section 53 which is read first. In the first correction unit 53, for example, detection of shock is performed on the surface of the wafer 12.

In addition, in the main control system 20 of the present embodiment, the first memory unit 55 and the second memory unit 56 are provided. The first spatula part 55 has an inclination angle θxp around the Y-side circumference of the second reference plane representing the imaging plane in the field of view field 13 on the wafer 12 and a square θyp around the X-axis and a reticle ( The focal position zO of the image forming surface at the center of the field of illumination field 13 when the center of 7) is on the optical axis of the projection optical system 11 is stored. On the other hand, in the second memory section 56, a square angle Θx is stored around the Y axis of the second reference plane (relative to the scanning direction) indicating the imaging plane on the entire surface of the exposure field (short region) on the wafer 12. .

Here, the first and second reference planes will be described in detail with reference to FIGS. 8A and 8B. FIG. 8A is a simplified illustration of the stage system of FIG. The reticle stage 9 which scans the reticle 7 in the X direction in FIG. 8A now moves along the running surface (guide surface) 10a, and the hatton forming surface of the reticle 7 is placed on the running surface 10a. The solution is inclined with respect to the predetermined angle. In addition, the X stage 15X which scans the wafer 12 in the X direction is determined along the traveling surface 17Z, and the inclination angles around the Y axis and the X axis of the traveling surface 17a are adjusted to (0, 0). It shall be done.

In this case, the image plane in which the pattern of the reticle 7 in the illumination region 8 is projected to the field of view field 13 through the projection optical system 11 with the article 7 at the center in the scanning direction is The inclination angle θxp θ yp around the Y axis X axis with respect to the traveling surface 17a of the first reference plane 62, the first reference plane 62, and the second reference plane 62, and the focal positions z0 of the reference planes 62 in advance Saved. The surface of the wafer 12 is set to conform to the first reference plane 62 by controlling the amount of expansion and contraction of the three actuators 16A to 16C (see FIG. 7). However, in FIG. 8A, when the position of the reticle 7 moves in the X direction along the running surface 10a and the illumination region 8 fluctuates in the Z direction, the image plane of the image in the field of view 13 is the first reference plane 62. ) Fluctuates in the Z direction for life. The twenty-first reference plane indicates the amount of variation in the Z direction of the first reference plane 62.

For example, when the scanning direction of the wafer 12 is set to the + X direction, the focal position when the position of the wafer 12 is at the position XO shown in Fig. 8A is shown as z0 and the position of the wafer 12 is shown in Fig. 8B. When the focal position at the time of changing to the illustrated position X is zA, the following relationship is approximately established.

zA = (X-X0) θxp + z0 ... equation 1

Here, in order to consider the influence by the scanning of the reticle 7, it is assumed that the pattern forming surface of the reticle 7 is inclined at a predetermined angle in the scanning direction with respect to the running surface 10a of the rackle 7. As a result, as shown in FIG. 8B, the position of the image plane in the center of the field of the Iewooe Joya field where the reticle 7 was scanned in the X direction is the second reference plane 65 (an inclination angle with respect to the scan direction (the Y-axis perimeter) The angle of inclination at) is the plane of Θx).

That is, the distance in the X direction between the point 63A on the pattern forming surface of the reticle 7 on the optical axis AX of the projection optical system 11 and the point 64A separated in the + X direction from this point in FIG. 8A (x-x0 ) The dose magnification of the projection optical system 11 with the point 64B as the point 64B on the point 63A and the point 63B spaced on the wafer 12 by the distance X-X0 in the X direction. Using B (for example, 1/4, 1/5, etc.), the following relationship is assumed.

X-X0 =-β (x-x0) ... Equation 2

Further, since the square of the second reference plane 65 is Θx and the focal position when the substrate 12 is at the position X0 shown in Fig. 8A is z0, the focal position in the center of the irradiation field in the state of Fig. 8B is almost Convert to the focal position zB shown in equation (3).

zB = (X-X0) Θx + z0 ... Equation 3

Thereafter, the reticle 7 and the wafer 12 are scanned at a speed ratio β in the -X direction and the + X direction, respectively, with the inclination angle and the focal position of the wafer 12 fixed in the state shown in FIG. 8A, as shown in FIG. 8B. As described above, when the point 64A on the reticle 7 reaches the optical axis AX, the point 64B reaches the optical axis AX on the wafer 12. But on the reticle AX. However, since the illumination region on the reticle 7 is displaced in the Z direction, the position of the shop 64C through the projection optical system 11 of the point 64A on the reticle 7 is spaced δz in the Z direction with respect to the point 64B. As far away. Here, in FIG. 8, the first square 63B on the wafer 12 side and the current store 64C pass along the same plane as the square θyp of the first reference plane 62. When the reference plane 65 is used, a straight line connecting the shops through the projection optical system 11 on the optical axis AX of the reticle 7 when the reticle 7 and the wafer 12 are scanned in the -X and + X directions, respectively This is on the second reference plane 65. In other words, the image forming surface of the pattern of the reticle projected on the exposure field (short region) on the wafer 12 becomes the reference surface.

In the present embodiment, the square angle θx around the Y axis of the second reference plane 65 is measured in advance. Thus, the distance δz between the point 64B on the wafer 12 and the shop 64C in FIG. 8B is determined by using the square angle θx p of the first reference plane 62 and the inclination angle x of the second reference plane 65. Becomes

δz = zB-zA = (X-X0) (Θx-θxp) ... Equation 4

Thus, focusing (autofocus) is performed by changing the heights of the three actuators 16A to 16C in parallel by the interval δz. Leveling is already complete at this point.

Returning to FIG. 7, the first reference planes in the first storage unit 55 are supplied to the subtracting units 54A and 54B as the target values of the inclination angles, respectively. In the subtracting sections 54A and 54B, the inclination angle deviation Δθx (= θxp-θx) Δθy (= θxp-θy) is supplied to the target position / speed conversion unit 58, respectively. The inclination angle θxp in the first storage unit 55 and the focal locus z0 of the image forming surface in the mood state and the inclination angle θx of the second reference plane in the second storage unit 56 are supplied to the focus position correcting unit 57. In addition, the Z-talt stage 14 (the X coordinate of the wafer 12) measured by the laser interferometer 23X of the X-axis is supplied to the focus position corrector 57 and the target position / speed converter 58, and The Y coordinate of the Z tilt stage 14 measured by the laser interferometer 23Y is supplied to the target position / speed converter 58.

The focus position correcting unit 57 calculates the gap amount δz of the focus position from Equation 4 by using X coordinate of the Z tilt stage 14 in the reference state as X coordinate of the current Z tilt stage 14 as X. The focus position z0 is added to the gap δz to obtain the target focus position zP, the target focus zP is obtained, and the target focus position zP is supplied to the subtractor 54C. As a result, the deviation? Z (= zP-z) of the focus position is supplied from the subtraction section 54C to the target position / speed conversion section 58.

In the target position / speed conversion section 58, three actuators 16A, 16B, and 16 (C) when the optical axis of the projection optical system 11 is the origin from the X coordinates of the supplied Z ult stage 14 first. The coordinates (X1, Y1) (X2 Y2) and (X3, Y3) of each working point of) are calculated. The target position / speed converter 58 stores the root gains Kθx, Kθy, and Kz of the position control system at the inclination angle θx inclination angle θy and the focal position z, respectively. The speed storage values VZ1, VZ2 and VZ3 are calculated by the actuators 16A, 16B and 16C, respectively.

VZ ₁ Kθ x 0 0 X1 Y1 1 Δ θ x

VZ ₂ = 0 Kθy 0 X1 Y2 1 Δ θ y

VZ ₃ 0 0 KzX3 Y3 1 Δ z

Since the coordinates X1, Y1-(X3, Y3) of the actuators 16A-16C change as the wafer 12 is scanned, the target position / speed conversion section 58 can be a wafer 12, for example. The speed command values VZ1 VZ2 and V23 are calculated by performing the calculation of Equation 5 each time the position of is changed by a predetermined step or in predetermined time intervals. In these places, the command values V21 to V23 are supplied to the speed controller 60, and the speed controller 60 drives the actuators 16A to 16C through the power amplifiers 61A to 61C. The actuators 16A to 16C are also driven. In addition, a speed detection signal is fed back from the speed controller 60 to the detection signals of the speeds at the rotary encoders 43A to 43C (the same as the rotary encoder 43 in FIG. 6) inside the actuators 16A to 16C. . As a result, the actuators 16A to the tip portions are respectively driven in the directions at the driving speeds V21 to V23.

The position and the inclination angle on the surface of the wafer 12 after being driven by the actuators 16A to 16C are measured by the compaction AF sensor 25 of FIG. 1 and the least-squares calculation unit 52 of FIG. The deviation between the measurement result and the target value and the target position / speed conversion unit 52 and the like are measured, and the deviation between the measurement result and the target value and the target position / speed conversion unit 58 are fed back. As such, during the scanning exposure, the tilt angle and the focal position of the Z tilt stage 14 are servo-controlled so that the field of view field 13 of the wafer 12 always forms a projected image of the pattern in the illumination region 98 of the reticle 7. The exposure is performed in a state coinciding with the surface. Next, the second reference plane 65 corresponding to the inclination angles θxp, θyp of the first reference plane 62 corresponding to the imaging plane in the field of view field 13 shown in FIG. 8 and the imaging plane of the exposure field on the wafer 12 is shown. An example of the measuring method of the inclination angle Θx will be described.

First, with respect to the first reference plane 62, as shown in FIG. 8A, the reticle 7 is stopped at the center of the scanning direction, and then the wafer stage is driven in the planar direction, so that the wafer 12 is subjected to the step-and-repeat method. The pattern image in each illumination area | region 8 is test-printed (condition extraction exposure) to the multiple area | region (region exposed by the illumination field 13). At this time, the surface of the wafer 12 is set parallel to the traveling surface 17a, that is, at the inclination angles (0, 0), and the focal position (Z coordinate) of the wafer 12 is changed in sequence for each exposure. Then, the wafer 12 is developed and the distribution of the best focus position at each point in the field of view 13 is obtained by investigating the resolution of the projected image, and the inclination angles θxp and θyp of the first reference plane 62 are obtained by plane approximation. ) And the focal position z0.

Next, with respect to the second reference plane 65, the inclination angles θxp and θyp of the second reference plane 62 are first obtained by the above-described method, and the first storage unit 55 of FIG. Set to. In addition, the value 0 (same value as the running surface 17a), which is written as the inclination angle θx of the second reference plane 65, is set in the second storage unit 56 in FIG. Thereafter, the target value of the focal position (Z coordinate) is changed by a predetermined interval for each exposure. A test print is performed by the step-and-scan method. In each scan exposure at this time, the focal position is fixed to the wafer 12 in a state in which the inclination angle coincides with the first reference plane 62. Then, the distribution of the best focus position in each exposure field (short region) of the wafer 12 is obtained by measuring the resolution of the image obtained by developing the wafer 12. From the gun cloth, the inclination angle θx around the Y axis of the second reference plane 65 and the inclination angle Θy around the X axis (this is almost equal to the inclination angle θyp of the first reference plane 62) are obtained. As a result, the inclination angle of the second reference plane 65 indicates the distribution of the best focus position in the exposure field. The r inclination angle Θx is stored in the second storage unit 56 in FIG. 7 through an input / output device (not shown).

In addition, in FIG. 2, measurement points P21 to P43 for tilt angle focal position detection are distributed in the field of view field 13, but those measuring points P21 to P43 may deviate from field of view field 13. As shown in FIG. In addition, the number and arrangement | positioning of all the measurement points P11-P53 are not limited to FIG. 2, For example, you may arrange | position a measurement point with a difference to a X direction.

In addition, in the above embodiment, the multi-point AF sensor 25 is used to detect the inclination angle of the field of view field 13 on the wedgeper 12. However, instead of the multi-point AF sensor, the measurement point uses one point of AF sensor to detect the inclination angle. For example, it is possible to use a leveling sensor of a lifetime beam-like incidence method which irradiates the surface of the wafer 12 at an oblique angle at an angle and detects the inclination angle of the surface from the horizontal gap at the condensing position of the reflected light. According to the projection exposure apparatus of the present invention, the inclination angle of the projection with respect to the exposure area (joy field) on the photosensitive substrate due to the inclination of the mask projection optical system is the inclination angle of the first reference plane. In addition, the roughness of the projection on the exposure field on the substrate due to the difference in the square of the running surface (guide surface) between the stage on the mask side and the stage on the substrate side becomes the inclination angle of the second reference plane. Therefore, by controlling the inclination angle and the focal position based on these two reference planes, even if the height of the imaging plane of the projection optical system changes during the scanning exposure, the surface of the substrate can be fitted to the imaging plane continuously with high tracking accuracy during the scanning exposure. There is an advantage.

As a result, it becomes easy to obtain a homogeneous projection image across the entire exposure field (short region) on the substrate, and high imaging characteristics can be maintained even when the imaging surface of the projection optical system has a narrow depth of focus. In other words, the margin of focus (focus margin) increases.

Incidental angle of inclination of the first reference plane When the inclination angle (state of change in focus position) of the second reference plane is measured in advance and stored, the control sequence is simplified and the focus position is simply used during scanning exposure. The speed can be increased at the following speed for the change of.

Next, an embodiment of a focus detection method in which the settling time is shortened and the efficiency is improved will be described.

FIG. 10 shows the drive system of the three actuators 16A to 16C in FIG. In this example, the contact between the actuator 16A and the Z tilt stage 14 detects the position (height) P21 in the Z direction by integrating the pulse sources output from the rotary encoder 43 with the counter 16A. .

As shown in FIG. 10, the other actuators 16B and 16C have the same configuration as the actuator 16A, and the actuators 16B and 16C are also provided with rotary encoders 43B and 43C for detecting the moving speed, respectively. have. In addition, a counter 161C for integrating the pulse signals from the rotary encoders 43B and 43C is provided. Positions PZ2 and PZ3 in the Z-direction of the contacts between the actuators 16B and 16C and the Z tilt stage 14 are detected by the counters 161B and 161C, respectively.

In the main control system 20 of FIG. 10, the focal positions at the measurement points P21 to P43 in the field of view field 13 in FIG. 2 in the addresses 51 21 to 51 43 of the memory 51, respectively. Digital focus signals are shown.

In addition, these focus signals are rewritten in predetermined sampling periods and in order. The focus signal read out from the addresses 51 21 to 51 43 is supplied to the least-squares calculation unit 52 in parallel. The first square method calculation unit 52 conforms to the surface of the field of view field 13 according to the least square method based on the nine focus signals corresponding to the nine measurement points P21 to P43 in the field of view field 13. Determine the plane. The focal position (Z coordinate) z at the center of the determined plane, the inclination angle θx around the Y axis and the inclination angle θy around the X axis are obtained. These inclination angles θy and the focal position Z are supplied to one input portion of the multiplexer 153.

In addition, the positions PZ1, PZ2, and PZ3 in the Z direction of the corresponding actuators 16A to 16C output from the counters 161A to 161C are the stage position calculation unit within the main control system 20 ( 157). The stage position calculation unit 157 is also supplied with the X and Y coordinates of the Z tilt stage 14 (wafer 12) measured by the laser interferometers 23X and 23Y. In this case, the stage position calculation unit 157 first coordinates of the three actuators 16A, 16C, and 16D in the coordinate system displaying the X coordinate and the Y coordinate with the optical axis of the projection optical system 11 as the origin. (X1, Y1) and (X2, Y2) and (X3, Y3) are calculated.

9 shows a coordinate system with the optical axis AX of the projection optical system 11 as the origin (0, 0). In FIG. 9, the guide surface 162 shows the guide surface (running surface) when the X stage 15X and the Y stage 15Y become. The straight line 163 indicates the intersection of the plane including the three actuators 16A to 16C and the contact point of the Z tilt stage 14 and the plane perpendicular to the X axis through the origin and the X axis. Similarly, the straight line 164 indicates the intersection of the plane representing the contact point of the three actuators 16A to 16C and the Z tilt stage 14 and the plane perpendicular to the origin and the Y axis passing through the Y axis. The angle Θx formed by the straight line 163 with respect to the guide surface 162 and the angle Θy made by the straight line 164 with respect to the guide surface 162 respectively indicate the inclination angle with respect to the guide surface 162 of the bottom surface of the Z tilt stage 14. The focal gap amount in the optical axis AX passing through the origin of the bottom surface of the Z tilt stage 14, that is, the focal gap amount PZ at the origin, is the distance from the guide surface 162 to the straight lines 163 and 164. Also, in Fig. 9, the positions PZ1, PZ2, and PZ3 in the Z direction are shown between the straight lines 163 and 164 and the guide surface 162, but these are not actual values, but the X axes are respectively. And Y-axis values. Also, the positions PZ1, PZ2, and PZ3 in the Z direction are calibrated on the basis of the guide surface 162 and the focal positions Z and the square angles θx and θy of the plane calculated by the least-squares calculation unit 52 are also guide surfaces ( It is calibrated based on 162).

At this time, the stage position calculation unit 157 of FIG. 10 calculates coordinates X1 and Y1 to X3 and Y3 of the three actuators 16A to 16D and positions PZ1 to PZ3 in the Z direction. The angles of inclination θx, θy and the focal position PZ of the bottom surface of the Z tilt stage 14 are calculated by substituting on.

Θ x X1 Y1 1 ^-1 PZ1

Θ y = X2 Y2 1 PZ2 ... Equation 6

PZ X3 Y3 1 PZ3

The square Θx, Θy and focal position PZ calculated back to FIG. 10 are supplied to the wafer model portion 158. The wafer model unit 158 is also supplied with information of the X coordinate and the Y coordinate of the Z tilt stage 14. The wafer model unit 158 presets the inclination angles θx, Θy and focal position PZ of the bottom of the supplied Z tilt stage 14 and the current Z tilt stage 14 (coordinates (X, Y) of the wafer 12). The inclination angle θx 'around the Y axis of the virtual surface of the wafer 12, the inclination angle θy' around the X axis, and the focal position Z 'are obtained based on the model of the wafer 12. The inclination angle θx' of the virtual surface of these wafers ,? y 'and the focal position Z' are supplied with respect to the multiplexer 153 to the tilt angle and focal position of the virtual surface of the wafer 12 outside the actually measured square and focal position of the surface of the wafer 12. In the embodiment, focusing and leveling control are performed while switching between direct control based on actual measurement of the surface of the wafer 12 and model following control based on the state on the virtual surface of the wafer 12. Switching between control methods Ming directs the operator to the control unit 155 in the topic control unit 20 via the input device 160. This control is performed according to the division of the coordinates (X, Y) of the Z tilt stage 14, for example. The instruction is sent to the focal position switching determining unit 154 in the form of indicating whether to use the method.

The X position and the Y coordinate of the Z tilt stage 14 are also supplied to the focal position switching determining unit 154. The focus position switching determining unit 154 supplies a multiplexer 153 with a control signal instructing switching of the control method in accordance with the supplied coordinates. In the multiplexer 153, the square angles θx, θy and the focal position Z are selected and supplied to the subtractors 156A, 156B, and 156C, respectively, when the direct operation is performed based on the measurement values of the surface of the wafer 12. When model tracking control based on the state of the virtual surface of 12) is performed, the inclination angles θx ', θy', and the focal position Z 'are selected and supplied to the subtraction parts 156A, 156B, and 156C, respectively.

In addition, the projection when the coordinates of the Z tilt stage 14 are at the predetermined reference points X0 and Y0 with reference to the guide surface 162 (see FIG. 9) of the stage on the wafer side, for example, by a test print or the like. Z0 is calculated | required as the inclination-angle (theta) x0 around the X-axis of the imaging surface of the optical system 11, the inclination-angle (theta) y0 around the Y-axis, and the position (focusing position) in the Z direction. These inclination angles? X0 inclination angles? Y0 and the focusing position Z0 are obtained. These inclination angles θx0, the inclination angles θy0 and the focusing position Z0 are stored in the storage unit in the control unit 155. Thus, when the coordinates of the Z tilt stage 14 are moved to arbitrary coordinates (X, Y), the inclination angles θxR, θyR and the focusing position zR of the imaging surface with respect to the guide surface 162 of the control unit 155 are determined as follows. Calculate from the approximate equation.

θxR = θx0

θyR = θy0

zR = (X-X0) θx0 + (Y-Y0) θy0 + Z0 ... Equation 7

The inclination angles θxR, θyR and the focusing zR of the imaging surface are supplied from the subtraction sections 156A, 156B and 156C as target values, respectively, and the target position / speed from the subtraction sections 156A, 156B and 156C. Deviation [Delta] [theta] x with respect to the target value with respect to the conversion unit 159, respectively. Δθy and the deviation ΔZ of the focal position are supplied. For example, the deviation [Delta] [theta] x of the inclination angle is ([theta] xR-[theta] x) or ([theta] xR-[theta] x '). In addition, the Z tilt stage 14 (the X coordinate and the Y coordinate of the wafer 12 is also supplied to the target position / speed converter 159.

In the target position / speed conversion section 159, three actuators 16A, 16B, and (in the case where the optical axis of the projection optical system 11 is the origin from the X-coordinate Y-coordinates of the supplied Z tilt stage 14 first ( The respective coordinates X1, Y1, (X2, Y2) and (X3, Y3) of 16C) are calculated. In addition, the loop gains Kθx, Kθy, and Kz are stored in the target position / speed converter 159 in advance in each of the position control systems of the square deviations Δθx, θy and the deviation Z of the focus position. The target position / speed converting section 159 is, for example, each of the three actuators 16A, 16B, and 16C in the following equation each time the position of the woofer 12 changes by a predetermined amount or at predetermined time intervals. The speed command values VZ1, VZ2 and VZ3 are calculated.

VZ ₁ Kθx 0 0 X1 Y1 1 Δθx

VZ ₂ = 0 Kθy 0 X1 Y2 1 Δθy ... Equation 5

VZ ₃ 0 0 Kz X3 Y3 1 Δz

These speed values are supplied to the waiter stage control system 124 by the command values VZ1 to VZ3, and in the wafer stage control system 124, the front end portions of the respective actuators move to the speed command values VZ1, VZ2, and VZ3, respectively. The actuators 16A, 16B, and 16C are driven by the servo control method. Thereby, control of focusing and leveling of the surface in the field of view field 13 of the wafer 12 is performed.

As a result of the shear, the positions PZ1, PZ2 and PZ3 of three places in the Z direction of the bottom of the Z tilt stage 14 driven by the actuators 16A to 16C are changed and Z of these three places is changed. The tilt position and the focal position of the virtual surface of the wafer are determined by the stage position calculation unit 157 and the wafer model unit 158 from the position in the direction. In parallel with this, the angle of inclination of the surface of the wafer 12 after the Far East is measured by the multipoint AF sensor 25 of FIG. 1 and the least-squares calculation unit 52 of FIG. The deviation from the target value is fed back to the target position / speed converter 159. As a result, autofocus and haute level work is performed.

Here, if the control mechanism of the projection exposure apparatus of the embodiment shown in FIG. 1 and FIG. 10 is simplified and displayed, it will become as shown in FIG. In this FIG. 14, the wafer 12 is held on the wafer stage 165, and the inclination angle and the focal position of the surface of the wafer 12 correspond to the nensor 74 (the sensor 25 in FIG. 1). The measured value is supplied to one input part of the switching part 75 (corresponding to the multiplexer 153 of FIG. 1). In addition, the inclination angle and the height of the predetermined member of the predetermined member in the wafer stage 165 are measured by the sensor 76 (corresponding to the encoder 43 in FIG. 10). This measured value becomes an estimate of the tilt angle and the focal position of the virtual surface of the wafer 12 through the wafer model portion 77 (corresponding to the wafer model portion 158 in FIG. 10), and this estimated value is the switching portion 75. Is supplied to the other input of the input. The switching unit 75 is supplied to the subtraction unit 78 (corresponding to the subtraction unit 156 in FIG. 10) selected by the external switching command. Here, the stage system (Z tilt stage 14, Y stage 15Y, stage 15X, etc.) on which the wafer 12 is mounted is represented by the wafer stage 165. The same applies to the following.

The subtraction unit 78 supplies the control system 79 (corresponding to the wafer stage control system 123 and the target position / speed switching unit 159) obtained by subtracting the measured value or the estimated value from the target value supplied from the outside. In the control system 79, the inclination angle and the height of the wafer stage 165 are controlled so that the deviation becomes zero.

In the following embodiment, the focusing and gaveling control is performed while switching between direct control based on actual measurement of the surface of the wafer 12 and model following control based on the state of the virtual surface of the wafer 12. A specific example is demonstrated.

Basically, these two control switching is mainly performed in the following three cases. ① When the detection area of the multi-point AF sensor 25 of FIG. 1 comes out from the surface of the wafer. ② When the detection area of the multi-point AF sensor 25 enters the outside from the surface of the wafer. ③ The flaw has a flaw on the surface of the wafer. When there is an area unsuitable for the control of alignment or leveling, each case will be described below.

First, as shown in FIG. 11A, the case where the field of view field 13, which is the detection area of the multi-point AF sensor 25, changes from the outside of the surface of the wafer 12 to the inside in response to the stepping movement or scanning of the wafer. At this time, when the front end of the wafer stage 165 is in the region 66E, the detection region of the multi-point AF sensor 25 is outside the surface of the wafer 12, so that the multiplexer 153 of FIG. The squares θx ', θy' and focal position z 'of the imaginary surface are selected.

In the wafer model 158 of FIG. 10, the thickness of the wafer holder and the thickness of the wafer 12, not shown in the thickness of the Z tilt stage 14, are added to the position PZ in the Z direction of the bottom of the Z tilt stage 14. The focal position z 'is obtained, and the square angles θx and θy of the bottom surface of the Z tilt resin 14 are inclined angles θx' and θy as they are. As a result, control of focusing and leveling is performed such that the surface of the wafer 12 conforms to its virtual surface. Then, by the stage position calculation unit 157 and the wafer model unit 158 at three positions PZ1 to PZ3 of the bottom surface of the Z tilt stage 14 after being driven by the actuators 16A to 16C. The inclination angles θx ', θ y' and the focal position z 'of the virtual surface of the wafer 12 are updated and the deviation between the value after this update and the target value is given to the target position / speed converter 159 as a new servo deviation. So-called closed-loop position servo control is performed.

After that, in FIG. 11A, when the wafer stage 165 moves again and enters the region 66A, it is determined by the focus position switching determination unit 154 of FIG. 10, the multiplexer 153 causes the least square method calculation unit 52 to perform It is switched to select the inclination angles θx, θy and the initial position z of. This is because, as indicated by the position Q1, the detection area of the AF sensor 25 (the whole of the field of view 13 moves on the wafer 12 so that the actual measured value becomes effective. 14) is servo controlled such that the inclination angles θx, θy and the focal position z of the actual surface of the wafer 12 coincide with the target values θxR and zR, respectively, and the surface of the wafer 12 by control using an imaginary surface during this switching. Since the focal point position is almost near the target value, the pulling time (correction time) from switching the control method to matching the culture value, that is, the imaging surface, within the predetermined allowable range on the surface of the wafer 12 is compared with the conventional example. It is shortened.

Next, as illustrated in FIG. 11B, the detection area of the multi-point AF sensor 25 (the field of view field 13 moves outward in the surface of the wafer 12 by the stepping movement or scanning of the wafer 12). In this case, when the tip of the wafer stage 165 is in the region 67A, the multiplexer 153 of FIG. 10 selects the inclination angles θx, θy and the focal position z in the least-squares calculation unit 52. It is switched and servo controlled to coincide with the imaging surface of the actual wafer 12. After that, when the tip of the stage 105 enters the region 67E, the focal position switching determining unit 154 stumbles, the multiplexing is performed. The racker 153 is switched to the wafer model portion 158 and servo controlled so that the virtual surface by the wafer model coincides with the imaging surface, as indicated by the position Q2, the detection area of the multi-point AF sensor 26. If it is located outside the wafer 12, multiple points This is because the detection value of the AF sensor 25 fluctuates greatly.

In addition, as shown in FIG. 11C, the control method in the case where there is a groove 68 region unsuitable for focusing leveling control on the surface of the wafer 12 will be described. One example of such a groove-shaped region 68 is a scan in one projection area when a plurality of chips are cut out from one projection area in a street laryn between adjacent projection areas or a projection exposure apparatus of, for example, a scanning exposure method. The groove-shaped region 68 may exist in the middle of the direction. In FIG. 11C, a groove-shaped region 68 exists in one projection area on the wafer 12, and the exposure table is exposed in a step-and-scan projection exposure apparatus. do.

In this case, if the wafer stage 105 is exposed by scanning in the left direction as indicated by the arrow, when the groove-shaped region 68 is in the region 69A 2, the multiplexer 153 of FIG. Focusing and leveling control is performed on the calculation unit 52 side and based on the measured value of the multi-point AF sensor 25. Thereafter, when the groove-shaped area 68 enters the area 69E and the detection area (the Joya field 13) of the multi-point AF sensor 25 enters the home-shaped area 68, the focus position switching determining unit 52 At the time of determination, the multiplexer 153 is switched to the axis of the wafer model unit 158, and control is performed to match the virtual surface with the image formation surface. This is because, as indicated by the position Z3, the focus position measured by the multi-point AF sensor 25 is lowered. This is because the focus position of 12) is increased and subsequent intake time is lengthened. As the virtual surface, a flat surface in the case where there is no groove-shaped region 68 is set.

Next, when the scanning exposure proceeds and it is determined that the groove-shaped region 68 reaches the region 69A 1 and the detection region of the multi-point AF sensor 25 does not reach the groove-shaped region 68, the multiplexer 153 The switching to the least-squares calculation unit 52 side is again performed, and focusing and leveling control is performed based on the measured values of the multi-point AF setter 25. By switching in this way, the pull-in time (correction time) immediately after passing through the groove-shaped area 68 can be shortened, and as a result, the efficiency of an exposure process can be improved by increasing a scanning speed, for example.

In addition, in the above-mentioned embodiment, the switching determination in the focal position switching determination unit 154 in FIG. 10 is performed with step information and lazy interferometer 23X previously given as information on the position of the wafer 12 via the input / output device 160. , 23Y is to compare the present coordinate position of the Z tilt stage 14 (wafer 12). Only information of 66A and 66E described in FIG. 11A Step information of 67A and 67E described in FIG. 11B and step information of 69A and 69E described in FIG. Is stored in the control unit 155 after being input. Also, as shown in FIG. 12, a determination sensor 71 may be used.

FIG. 12 shows an example in which the AF sensor 71 which detects the focus position of the detection area 70 preceded by the scanning direction is implemented separately from the multi-point AF sensor 25. Now, at 12 degrees, the center of the detection area of the multi-point AF sensor 25 and the center of the detection area 70 of the AF sensor 71 are separated by a distance d in a direction parallel to the ground of FIG. For example, when the focal position detected by the AF sensor 71 returns to the normal range outside the detection range when the wafer stage 165 is scanned by scanning to the left at the scanning speed Vw, the time d / Vw increases from there. After the elapse of time, the multiplexer 153 of FIG. 10 is switched to select the least-squares calculation unit 52 side. Thereby, switching of a control system can be performed correctly, without setting a switching range in advance.

In the present embodiment, as shown in FIG. 2, the first read areas 35A and 35B are provided, so that the first read area 35A in FIG. 2 can be used as the detection area 70 in FIG. . In this case, the AF sensor 71 may also serve as the multi-point AF sensor 25 of FIG. 1.

In addition, the wafer surface is not strictly a plane, but is normally smoothly deformed into a shape or a shape such as an axis-to-blue with respect to the center. Thus, in order to cope with such deformation of the wafer, the wafer model portion 158 of FIG. 10 of this embodiment modifies the wafer model (adaptably) according to the shift of the wafer 12 in the X direction and the Y direction. We adopt method. This is done by correcting the wafer model in order when focusing and leveling control is performed using the measurement results of the multi-point AF sensor 25.

FIG. 13 shows a case where the wafer whose surface is deformed is moved to the left in the wafer stage 165. First, as shown in FIG. 13A, when the X coordinate of the wafer stage 165 is XA, an approximate plane in the field of view 13 measured by the multi-point AF sensor 25, that is, the center of the field of field approximately 13 is approximately. In this case, the plane contacting the wafer 12 becomes the wafer model. In addition, as shown in FIG. 13B, when the X coordinate of the wafer stage 165 becomes XB, the multi-point AF sensor 25 will be taught in that state. The approximate plane in the field of view field 13 to be used becomes a wafer model. And when the multiplexer 153 of FIG. 10 is switched to the wafer model part 158 side, the approximate single side measured by the multi-point AF sensor 25 just before that is used as a wafer model. As a result, even when the wafer is deformed, the pull-in time when the control method is switched is shortened. In addition, in FIG. 2, the measurement points P21 to P43 for detecting the inclination angle and the focus position may deviate from the field field 13. The number and arrangement of the measurement points P11 to P53 as a whole are not limited to FIG. 2, but the measurement points may be arranged with a difference in the X direction, for example.

In the above-described embodiment, the multi-point AF sensor 25 is used to detect the inclination angle of the field of view field 13 on the wafer 12, but instead of the multi-point AF sensor, an AF sensor having one measurement point is used for the inclination angle detection. For example, a leveling sensor of a parallel beam inclined incidence method which irradiates the surface of the wafer 12 at an oblique angle and detects the inclination angle of the surface in the horizontal gap of the condensing position of the reflected light may be used.

Moreover, this invention is applicable also to the projection exposure apparatus (stepper etc.) of a batch system. In this case, when the present invention is applied to the projection exposure apparatus of the batch exposure method, as in the example of FIG. 11, an auxiliary AF sensor for detecting the focus position of the preceding detection area is disposed separately from the original AF sensor, for example, during stepping movement. It is also possible to switch the control method by using the measured value of the egg auxiliary AF sensor.

As described above, the present invention is not limited to the above-described embodiments, and various configurations can be taken without departing from the gist of the present invention.

According to the exposure apparatus of the present invention, in a region where the original focusing of the surface of the wafer or the like is not subject to control, and in the region where this is present or in the outer region of the substrate, the exposure apparatus detects the height detected by the stage focus position sensor (encoder, etc.). Since the focus position of a board | substrate is controlled based on it, the amount of deviation in the target value of the focus position at the time of starting AF control using a board | substrate focus position detection sensor afterwards becomes small. Therefore, thereafter, the drawing time (correction time) until the drawing is completed can be shortened and the efficiency of the exposure process can be improved.

According to the exposure apparatus of the present invention, when a groove such as a chip boundary (street line) is present in one projection area on the substrate by the scanning exposure method, in the region of the groove, on the basis of the height detected by the focus position detecting sensor for the stage By controlling the focal position of the substrate, there is an advantage that the drawing time (correction time) at the time of starting the focusing control later using the focal position detection sensor for the substrate can be shortened.

When the focus position is predicted based on the height detected by the stage focus position sensor and the predetermined model, for example, the height detected by the stage focus position sensor even when the surface of the substrate is deformed. Since the focus position of the substrate can be controlled almost accurately based on the above, there is an advantage of shortening the drawing time when the focusing control for the substrate is subsequently used to start the focusing control.

Claims (26)

A projection exposure apparatus which scans the mask and the substrate synchronously with respect to the projection optical system in a state in which an image of a part of the pattern of the mask is projected to a predetermined exposure area on the photosensitive substrate through the projection optical system, and the predetermined projection with respect to the optical axis orthogonal plane. The projection image of the mask by the projection optical system on the basis of the inclination angle of the exposure area surface and the inclination angle detected by the position detection sensor and the position detection sensor to detect the focal position of the exposure area surface in the optical axis direction of the projection optical system. On the basis of the inclination angle control unit which controls the substrate surface at all times so as to be deviation from the first reference plane defined by the second reference plane, and the second reference plane determined by the distribution of the focus position on the exposure area surface and the focus position generated for scanning the mask. And a focal position control unit for controlling the substrate. The projection exposure apparatus according to claim 1, wherein the focus position control unit controls the substrate based on the reference plane outside the position in the optical axis direction of the first reference plane. The projection exposure apparatus according to claim 1, wherein the inclination angle control unit and the focus control unit have a storage unit, and the storage unit stores the inclination angle between the first reference plane and the second reference plane and the optical axis orthogonal plane. Exposure method of a circuit board which scans the said mask and the said board | substrate synchronously with respect to the said projection optical system in the state which projected the image of one part of the pattern of a mask to the predetermined exposure area | region on the photosensitive board | substrate through a projection optical system, As a) said optical axis orthogonal plane Detecting the inclination angle of the predetermined exposure area plane with respect to and the focal position of the exposure area plane in the optical axis direction of the projection optical system; and b) the mask with the transparent optical system based on the detected inclination angle. Controlling parallel to a first reference plane defined by the projection image of c) and c) based on a second reference plane defined by a distribution of a focal position on the exposure area plane and a focal position generated for scanning with the mask Controlling the substrate. 5. The method of claim 4, wherein the distribution of the focal position of the second reference plane is further determined in accordance with the focal position of the first reference plane. An exposure apparatus having a projection optical system for projecting a pattern on a mask onto a photosensitive substrate and a substrate stage for moving the substrate to the image plane side and the optical system in order to detect a second focal position of the substrate stage in the optical axis direction of the projection optical system. According to a focus position selector for selecting a focus position from among the first focus position or the second focus position according to the stage focus position detector and the surface state of the substrate, and according to the focus position selected by the focus position selector And a focus position control unit controlling a focus position of the substrate. A scanning type exposure apparatus which sequentially transfers an image of a pattern of a mask onto a substrate, comprising: a projection optical system for projecting an image of a portion of the pattern on the mask onto a predetermined exposure area of a photosensitive substrate company; and moving the substrate to an image plane side of the projection optical system A substrate stage, a drive system for synchronously scanning the mask and the substrate with respect to the projection optical system, a substrate focal position detection sensor for detecting a first focus position of the substrate in the optical axis direction of the projection optical system, and the projection A focus position detection sensor for a stage for detecting a second focal position of the substrate stage in an optical system and an optical axis direction, a storage unit for storing step information on the surface of the substrate, and step information of the substrate stored in the storage unit And among the first focus position or the second focus position depending on the driving position of the substrate by the drive system. According to any one of the focal position selector configured to select the location of the focal point, the focal position selected by the focal position selector exposure apparatus comprising a focus position control section for controlling the focus position of the substrate. The substrate for detecting the second focal position according to claim 7, wherein the stage focus position detector detects the height of the substrate stage, a predetermined substrate model set in advance, and a height detected by the sensor. Exposure apparatus which has a model part. An exposure method of a circuit board for projecting an image of a part of a pattern of a mask to a predetermined exposure area on a photosensitive substrate through a projection optical system, the method comprising: a) a first focal point of the predetermined exposure area on the substrate in the optical axis direction of the projection optical system; Detecting a position; b) detecting a second focus position of the substrate stage in the optical axis direction of the projection optical system; and c) the first focus position or the second focus according to the surface state of the substrate. Selecting a focus position from among the positions, and d) controlling the focus position of the substrate in accordance with the selected focus position. 10. The method of claim 9, wherein a1) detecting the first focus position comprises detecting an inclination angle of the substrate, and b1) detecting the second focus position detects an inclination angle of the substrate stage. . An exposure apparatus which transfers a pattern formed on the mask onto the substrate by moving the mask and the substrate in synchronism with each other, the surface position of the substrate being based on information on the traveling surface in the moving direction of the substrate stage on which the substrate is installed. Exposure apparatus including the surface position setting part to set. 12. The surface of the substrate according to claim 11, wherein the pattern of the mask is transferred onto the substrate through the projection optical system and at the same time the surface position setting unit is based on the movement information of the pattern formation surface of the mask in the optical axis direction of the projection optical system. Exposure apparatus to set the position. The movement information of the pattern formation surface of the mask in the optical axis direction of the projection optical system includes the tube information in the inclination of the pattern formation surface of the mask with respect to the running surface of the mask stage for installing the mask. Exposure apparatus. 13. The movement information of the pattern formation surface of the mask in the coaxial direction of the projection optical system according to claim 12, wherein the information on the amount of variation in the optical axis direction of the dose optical system of the image forming surface of the pattern formation surface during the synchronous movement. Exposure apparatus including. The exposure apparatus according to claim 11, wherein the traveling surface in the movement direction of the substrate stage includes a guide surface for guiding the movement of the substrate stage. 12. The exposure apparatus according to claim 11, wherein the surface positioning unit obtains the inclination of the projection surface of the pattern with respect to the traveling surface in the moving direction of the substrate stage. 12. The apparatus of claim 11, wherein the surface position setting unit feeds back the substrate driving unit for changing the surface position of the substrate, a calculating unit calculating a target value of the surface position of the substrate, and the substrate driving unit such that the surface position of the substrate is the target value. An exposure apparatus having a control unit for controlling. The exposure apparatus of claim 12, wherein the controller is configured to feedback control the driving speed of the substrate driver. An exposure apparatus which transfers a pattern formed on a fraud mask on the substrate as much as the mask and the substrate are moved in synchronization with each other, the storage unit storing step information on the substrate and based on the step information on the substrate stored in the storage unit. And a surface position controller for controlling the surface position of the substrate. The exposure apparatus of claim 19, wherein the pattern of the mask is transferred onto the substrate through a projection optical system, and the surface position controller includes a focus position controller that controls a focal position of the substrate in an optical axis direction of the projection optical system. Device. The exposure apparatus according to claim 19, further comprising an input device capable of inputting the step information by an operator. The exposure apparatus according to claim 19, wherein the pattern of the mask is transferred onto the substrate through a projection optical system and the step information is stored corresponding to a position in a predetermined coordinate system perpendicular to the optical axis of the projection optical system. The exposure apparatus of claim 19, wherein the step information includes information about an inside or an outside of the substrate. The exposure apparatus according to claim 19, wherein the step information includes information on the inside or outside of the substrate. 21. The substrate position control unit according to claim 20, wherein the surface position control unit is configured to detect a focus position for a substrate in the optical axis direction of the projection optical system of the substrate and a signal from the substrate focus position detection unit for the stored step information. An exposure apparatus having a judging section for judging whether it is valid or invalid. 25. The exposure apparatus according to claim 24, wherein the surface position control unit controls the surface position such that the surface position of the substrate coincides with a predetermined virtual surface when the signal from the focus position detecting unit for the substrate is determined to be effective.