JPS59177928A - Device for projection exposure - Google Patents

Abstract

PURPOSE:To adjust the focus of a projection exposure device accurately and moreover easily, and to enable to regulate in a short time by a method wherein a photoelectrically scanning microscope is fixed to an alignment optical system, a pattern signal is detected as an electric signal, and adjustment of the focus is performed by detecting electrically the focus position whereat intensity of the signal becomes to the maximum. CONSTITUTION:A wafer 1 is vacuum attracted to the stage of a wafer table 3, and transferred to the under part of an alignment optical system 8 according to a running table 6. A focus slip quantity is detected, and the wafer is transferred to adjust the focus. The running table 6 is transferred to the right direction holding the condition thereof as it is, and transferred under a wafer surface positioning part 9. At this time, detecting points on the wafer 1 are detected transferring the table, the output signal of a non-contacting displacement meter is processed according to an A/D converter, and the position is operated according to a computer. The result thereof is the focus coinciding face of the wafer 1 and a mask 2. At printing time, the positions existing the detecting points of nine pieces on the surface of the wafer are detected according to the non-contacting displacement meter, and the running table 6 stops at the right edge part. The wafer 1 is transferred as to make the surface of the detecting points at this time to coincide with the previously operated focus coinciding face.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a projection device that performs 4' turn transfer by projecting and imaging a mask gloss pattern onto a wafer surface, and more specifically, relates to a projection device that performs 4' turn transfer by projecting and imaging a mask pattern onto a wafer surface. A projection optical system for projecting an image onto the surface, a means for positioning the wafer surface by positioning the wafer placed on the wafer table under a wafer surface positioning unit, and a projection optical system for projecting from the wafer surface. The present invention relates to a projection exposure apparatus having an alignment optical system for detecting a focal position shift.

[Background of the invention]

In a projection exposure apparatus for processing a circuit pattern on the surface of a semiconductor, in order to project and image a mask pattern on the wafer surface with high resolution, the wafer surface must be accurately positioned within the focal depth of the imaging plane. Highly accurate focusing is the most important technical element. An example of a conventional projection exposure apparatus is shown in FIG. 1, which is a schematic front view. Wafer 1
and mask 2 are mounted and held on a wafer table 3 and a mask table 4, respectively, in order to match the patterns of both, and these tables 3 and 4 are mounted on a stone surface plate 5 via an air bearing guide (not shown). is mounted on a traveling table 6 that is movable left and right in the drawing (the drive unit is not shown). Projection optical system7. Alignment optical system 8. and the wafer 5 71 surface positioning section 9 is also mounted on the stone surface plate 5.

The mask 2 is irradiated from the bottom side with ultraviolet light emitted from the exposure light source 10 provided at the bottom of the stone surface plate 5, and the projection optical system 7
Then, the pattern of the mask 2 is imaged onto the wafer 1. At the tip of the alignment optical system 80 objective lens 11,
8-7 mirror 12 is ifl, mask 2 no J
? The light that has passed through the turn passes through the half mirror 12 and forms an image of the pattern of the mask 2 on the wafer 1. In the alignment optical system 8, the Noreen on the wafer 1 and the wafer 1
The pattern of the mask 2 projected and imaged thereon is simultaneously observed through a half-mirror 12° objective lens 11, etc., and pattern alignment is performed. Note that when performing this pattern matching, ultraviolet components are removed from the light from the exposure light source 10 using a filter or the like.

The structure of the wafer table 3 and wafer surface positioning section 9 of this projection exposure apparatus will be explained based on FIG. 2. In FIG. 2, the wafer table 30 base member 13 is
The pace member 13 is fixed to the traveling table 6 shown in the figure.
X through the steel ball 14 on top of.

A 6-page Y stage 15 is placed. X, Y stage 15
can move freely in a horizontal plane along the upper surface of the pace member 13 and has two degrees of freedom. And this X
, Y stage 15 is moved by ±3 by a feed mechanism (not shown).
The position within the range of the gate is controlled in the traveling direction of the traveling table 60 (Y direction) and in the direction perpendicular thereto (X direction) within the horizontal plane. This X, Y stage 15
A theta stage 17 is rotatably attached to the theta stage 17 via a ball bearing 16, and a vertical shaft 18 is further attached to the theta stage 17. This vertical shaft 18 has a nut 1
9 is fitted and fixed, and the nut 19 is engaged with the feed screw (fixed to the theta stage 17 and directly connected to the shaft of 7'CA' Luss motor 2), so that the Noyals motor 21 can be driven. The vertical shaft 18 moves up and down,
Operates as two stages. The vertical shaft 18, which is the two stages, is fixed to the theta stage 17 so as not to rotate, and is supported so as to be vertically slidable.

A wafer mounting table 22 is placed above the vertical shaft 18, and a conical recess n on the upper surface of the vertical shaft 18 fits into a lower spherical seat of the evaporator mounting table 22. can be tilted freely.

In this way, the conventional Unihachi table 3 is provided with an XIY stage 15 on the pace member fixed on the running table 6, and the theta stage 17 is supported by the X and Y stages 15. It had a triple structure in which the vertical shaft 18, the wafer mounting table 22, and the wafer 1 were supported. In addition, a height reference plate 26 and three pieces of moss are placed on the lower surface of the surface positioning unit 9 so as to face the surface of the wafer 1 on the wafer table 3, and these are adjusted parallel to the reference plane. A mechanism (not shown) was provided to do this.

In this apparatus, with the above configuration, the wafer 1 is vacuum-suctioned to the wafer mounting table 22 using the suction hole 5 in the state shown in FIG. The traveling table 6 is moved to move the wafer 1 under the surface positioning section 9, the vertical shaft 18 is raised, and the surface of the wafer 1 is pressed against the iR rad 7, which is the height reference plate. Then, it will be corrected to a horizontal position. The pads 27 are placed at each vertex of an equilateral triangle whose center of gravity is the center of the wafer 1, and if they are placed at precisely a specified height above the focal plane of the projection optical system 7, the surface of the wafer 1 will be The height and inclination are positioned at a position higher than the focal plane of the projection optical system 7 by the above specified height. In this state, the inside of the hollow chamber is made into a vacuum, the wafer mounting table 22 is suctioned and fixed to the vertical shaft 18, and the vertical shaft 18 is further lowered accurately by the above specified height, so that the surface of the wafer 1 is placed at the focal depth of the projection optical system 7. It was moved in parallel.

After the above operation, move the traveling table 6, position the wafer 1 under the projection optical system 7, and place the wafer 1 on the X, Y stage 15.
The alignment mark provided on the wafer 1 is made to coincide with the alignment mark of the pattern of the mask 2 by moving the theta stage 17 and rotating the theta stage 17. In this state, the traveling table was once moved to the forward side, and then returned at a constant speed on the return path, while the pattern of the mask 2 was exposed and printed on the entire surface of the wafer 1. At this time, in order to align the surface of the wafer 1 with the focal plane of the optical system 7, the alignment optical system 8 moves the surface of the wafer 1 until the pattern of the mask 2 and the pattern of the wafer 1 can be clearly seen at the same time. The height and parallelism of the height reference plate 26 are matched, and then the pattern of the mask 2 is printed onto the wafer 1 and developed, and the specified height of the height reference plate 26 is set so that the obtained image is the clearest. was being corrected.

Such conventional technology has the following drawbacks. That is, the alignment optical system 8 slightly moves the objective lens 11 in the direction of its optical axis so that the pattern on the wafer 1 can be seen clearly, and then moves the vertical axis 18 of the Unihachi table 3 slightly in the direction of the optical axis. Since the mask 2 and wafer 1 are focused by repeatedly making the pattern of the mask 2 projected on the wafer 1 clearly visible, the accuracy of determining the best focus position is poor, and the best focus position is 0
Since the best focus is felt to be in a certain area (a certain width) in the front and back, it is difficult to achieve focus in the center, and there are also individual differences. Furthermore, the line width of the pattern of the mask 2 printed on the wafer 1 was more sensitive to focus than the 10th page, causing variations in line width. For this reason, the relationship between the position of the mask 2 and the line width was determined through trial printing, trial development, and measurement of the pattern width, and the mask 2 was fixed at the optimal position. It took a long time to make the test firing, as it was not possible to make adjustments using the equipment alone.

[Purpose of the invention]

The object of the present invention is to eliminate the drawbacks of the prior art, to enable accurate and easy focusing, to be adjustable in a short time, to be stable with little variation after adjustment, and to easily control gloss turn alignment. It is an object of the present invention to provide a projection exposure apparatus which can carry out exposure in a stable state and which does not damage the coating on the surface of a wafer.

[Summary of the invention]

The projection exposure apparatus according to the present invention includes a photoelectric scanning microscope attached to an alignment optical system, detects a pattern signal as an electrical signal, electrically detects the focus position where the signal magnitude is maximum, and uses a multifocal It is recommended that you do the matching. Furthermore, a non-contact displacement meter is provided in the wafer surface positioning section, and the non-contact displacement meter and an adjustment section that adjusts the height direction and parallelism of the wafer table are linked by a control circuit, and the lower part of the non-contact displacement meter is The position of the wafer moved by the traveling table is aligned by the adjustment unit with the reference position relative to the sea urchin calculated by the non-contact displacement meter.

In a preferred embodiment of the projection exposure apparatus according to the present invention,
The wafer table includes a pace member fixed to a traveling table and a set of feed points provided on the pace member in the X direction.
With the mechanism, two sets of feed mechanisms provided in the Y direction, and three sets of feed mechanisms provided in two directions, it is possible to move in the X and Y directions and adjust the height direction and parallelism. In addition, only the force in the feeding direction of each feeding mechanism is transmitted between each of the six sets of feeding mechanisms and the stage to allow movement in the feeding direction. A conductive member is interposed to allow each feeding mechanism to directly drive the stage independently.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS A projection exposure apparatus according to the present invention will be explained below based on drawings of embodiments. First, the outline of the apparatus of the embodiment will be explained based on FIG. 3, which is a schematic front view. As is clear from FIG. 3, this device also has a wafer table 3, a mask table 42, a stone surface plate 5, and the like in the conventional device shown in FIG.
．． Traveling table 6, projection optical system 7. Alignment optical system 8. Surface positioning part for sea urchin9. It has an exposure light source 1o (1
is a wafer, and 2 is a mask. ). Mask table 4° stone surface plate 5. Traveling table 6, projection optical system 7. Exposure light source 1
0 are of the same type as those shown in FIG. 1, so their explanation will be omitted, and 91 wafer table 3. The alignment optical system 8 and the sea urchin surface positioning section 9 will be explained in this order.

Explain about wafer table.

FIGS. 4 and 5 are a longitudinal sectional view and a plane 13T view, respectively, of an embodiment of the wafer table in the apparatus of the present invention. In the drawing, the track is a pacing member of the wafer table, which is fixed to the travel table (see FIG. 3). In order to constitute the feeding mechanism in the x, y and two directions, the pace motor is equipped with one nolus motor 29. and two pulse motors 30. and three A' pulse motors 31 (only two pulse motors 31 are shown in FIG. 4).

) is fixed. These noyarus motors 29,
The shafts of 30 and 31 have feed screws 32 and 33, respectively.
, 34 are fixed. Feed screws 32, 33, 3
Nut members 35, 36 and 37 screwed into the pace 28, respectively, suppress rotation relative to the pace path and allow sliding in the axial direction, thereby allowing the pace 28 to be tightly fitted.

The three nut members 37 include a floating pad 40 and a steel ball 41.
The stage 38 is supported via. Between the stage 38 and the pace path is a spring 42 that biases the stage's own weight.
is installed. Also, stage 38 is stage 3
8 and the pace path in the X direction, it is biased in the X direction and pressed against the nut member 35 via the floating pad 44, thereby positioning it in the X direction. Similarly, the stage 38 is biased in the Y direction by another spring 45 stretched in the Y direction between the page 14 stage 38 and the pager, and is pressed against the nut member 36 via the floating pad 46, so that the stage 38 is pushed in the Y direction. has been positioned. The floating pad 46 and the nut member 36 can be moved without resistance as air bearings (not shown). In this way, the wafer table has one set of feeding mechanisms provided in the X direction, two sets of feeding mechanisms provided in the Y direction, and three sets of feeding mechanisms provided in two directions. A vacuum suction cavity 39 is provided on the upper surface of the stage 38 so that the wafer 1 can be vacuum suctioned and mounted.

Reference numeral 9 in FIG. 4 is a wafer surface positioning section, which will be described later. In FIG. 5, nine x marks 47 (A-Q) shown on the surface of the wafer 1 indicate detection points of the wafer surface positioning section 9.

Next, the movement of this wafer table in the X and Y directions and the adjustment of the height direction and parallelism will be explained. First, the wafer 1 is vacuum-adsorbed onto the upper surface of the stage 38. Next, the three pulse motors are rotated to move the nut member 37 up and down as appropriate, thereby moving the stage assembly up and down and tilting it. At this time, since the floating nodes 44 and 46 have spherical and flat surfaces at both ends as air bearing surfaces, they do not provide resistance to the vertical movement or tilting of the stage, and the steel ball 41 has a sufficiently small diameter so that the stage 38 It is not the resistance of the slope. Next, the movement of the wafer 1 in the X and Y directions is carried out by pulse motors 29 and 3.
This is done by appropriately feeding the nut members 35 and 36 using the 0 button. At this time, since the floating pad 40 has an air bearing on its lower surface, it does not act as a resistance to the movement of the stage 38, and the floating pads 44 and 4.6 also have spherical and flat surfaces at both ends as air bearing surfaces, so the movement of the stage 38 It does not create rotational resistance. Further, the steel ball 41 supporting the stage 38 is supported by the floating pad 40 together with the stage back in a fixed state without swinging or rotating with the floating pad 40 or the conical surface of the stage 38, and is supported by the floating pad 40 along with the stage back.
The upper surface of the nut member 37 is precisely parallel to the focal plane of the lens. In this case, strictly speaking, a vertical deviation occurs due to a deviation in the parallelism between the top surface of the nut member 37 and the focal plane, but as in this embodiment, the top surface of the nut member 37 can be aligned with the focal plane with high precision. When finished in parallel, the above-mentioned deviation in the vertical direction is so small that it can be ignored even in the positioning of the Zabuchromin order.

In this way, the positioning of the stage in the X direction by the pulse motor 29 constituting one set of feed mechanisms, and the two
The stage 38 is positioned in the Y direction by the synchronous rotation of the two pulse motors 30 that constitute the set of feeding mechanisms 9. In parallel with this operation, each stage is rotated 90 times on two axes by the differential action of the two A'rus motors 30. That is, the operation corresponding to the theta stage 17 in the conventional apparatus shown in FIG. 2 can be performed.

As explained above, the six sets of feed mechanisms independently and directly push the stage to perform control in six degrees of freedom, resulting in high positioning rigidity.

Furthermore, the stage assembly is lightweight because it does not carry a feeding mechanism, and therefore does not impede controllability.

Explanation about alignment optical system.

Next, the alignment optical system will be explained based on FIGS. 6 to 79-13. First, a description will be given based on FIG. 6, which is a block diagram showing an alignment optical system in an embodiment of the apparatus of the present invention in relation to other constituent members. 48
This is an alignment scope that has been improved to use a high-resolution objective lens and has a built-in photoelectric scanning microscope, which forms the main part of the alignment optical system. The mask 2 is irradiated with light that has passed through the removable ultraviolet cut filter 49, and the edges and turns of the mask 2 to be projected onto the wafer 1 by the projection optical system 7 are interrupted by the plane mirror of the alignment optical system f48. 51, the mask pattern is projected onto the focal plane 53 of the objective lens 52 dedicated to the mask pattern, and is further projected onto the focal plane 53 of the objective lens 52 dedicated to the mask pattern. The beam is projected onto the p-scanner 56 by the beam combining half mirror 54 and the second objective lens 55.

In addition, the glossy turn of the wafer 1 is illuminated by a drop illumination device 57, and an objective lens 58 dedicated to the wafer pattern and a half mirror 54 for beam synthesis as in the case of the mask pattern are used.
and is projected onto the scanner 56 by the second objective lens 55.

59 Alignment scope 48 focusing drive 18
It is a page mechanism, and the alignment scope 48 is connected to the projection optical system 7.
As well as moving in the optical axis direction, the movement position signal (a)
is sent to the peak value position detection circuit 61. 62 is a peak value detection circuit, which receives an electrical signal 6 from the scanner 56.
3 into a mask and a wafer, and detect the peak values 64 and 65 of each signal.

The peak value position detection circuit 61 uses the peak values 64 and 65 from the peak value detection circuit 62 as the objective lens movement position signal 6.
The objective lens movement position at which the peak value of 64°65 for the mask and wafer becomes the maximum is detected from the change characteristics of how it fluctuates in response to the change in 0.

66 is a focusing circuit, which subtracts the mounting position error amount (constant value) of the two objective lenses 58 and 52 of the alignment scope 48 from the distance corresponding to the difference between the sea urchin beak value position signal and the mask beak value position signal. The wafer stage 3 is moved in the optical axis direction by the distance to focus.

7, 8, 10, and 11 explain the details of the process from the scanner 56 to the peak value detection circuit 62 or the peak value position detection circuit 61 in FIG. 6. .

FIG. 7 (Al is a pattern diagram projected on the scanner 56, select a location where the mask pattern 67 and the wafer pattern 68 do not overlap but are in the same field of view, and the patterns intersect at right angles to the scanning line 69. Scanner 5
In step 6, a known slit scanner, television camera, fort diode cell, etc. are used to obtain a scanning signal as shown in FIG. The operator specifies ranges 72 and 73 of the location of the edge 71 of the wafer.As shown in FIG. Scanning signal 6
3 and inputted to the oscilloscope (3 phenomena) 78 and observed there.

The scanning signal 63 is differentiated by a differentiating circuit 79, resulting in a waveform sensitive to focus as shown in FIG. 7 (C1).

The output signal of the differentiating circuit is inputted to the dart circuits so and si, and the output signal of the timing signal generation circuits 74 and 75 is
, 77, it is divided into a mask signal 82 and a wafer signal 83, and the peak values 84, 8 of each waveform are
5 is detected by peak height detection circuits 86 and 87 which are a combination of a maximum value hold circuit and a minimum value hold circuit, and a mask peak value signal 64 and a wafer peak value signal 65 are obtained.

FIG. 9 is an overall block diagram of a method for automating the discrimination between mask pattern signals and wafer/turn signals in FIGS. 7 and 8.

A shutter 88 and its insertion/removal mechanism 89 are added to the exposure light source 10, and a blinking device 90 of the vertical illumination device 57 for the wafer pattern is added.

FIG. 10 is a block diagram of the peak value detection circuit in this case. A mask illumination signal 92 and a wafer illumination signal 93 are output alternately from a mask/wafer illumination switching circuit 91, thereby switching the illumination and at the same time switching the differential signal of the scanning signal 63 to the differential signal gate circuits 80 and 81.

After that, the mask and wafer peak value signals 64 and 65 are obtained in the same manner as in FIG. 8.

According to this method, the mask pattern and the wafer pattern or turn can be distinguished by simply switching the illumination, and there is no problem even if the two patterns overlap, and they can be placed at any position within the scanning range. It is easy to automate, and is particularly advantageous when it is desired to focus at the beginning of the slide before positioning the wafer 1 in a printing machine.

Figure 11 shows a circuit block diagram (Figure A), pattern diagrams (Figures B, C, and D), and signal diagrams when automatically identifying masks, turns, and wafer patterns using target marks for automatic alignment. It is a waveform diagram (E figure). (A1
The figure shows a peak value detection circuit, in which the timing signal 7 is automatically
6, 77 are output. The rest is the same as in FIG. Figure C81 shows the target pattern 67 of the mask on one axis, which has nine turns (two bar shapes) with an interval F. (Figure 0 shows the wafer tag and tar 768,
It is a single bar pattern. The fD1 diagram is the A' turn combined and projected onto the scanner. 69 is a scanning line. The upper part of the fE1 diagram shows the waveform of the scanning signal obtained by scanning the pattern shown in the figure (■). The mutual spacing between the three peaks of the waveform is G, H, and J as shown in the figure, and the spacing of the mask pattern is F.
Select the interval closest to the interval corresponding to 22.1 among G, H, and J. Indicate this interval, judge the two peaks to be the mask pattern, and use the rest as the pattern for the sea urchin. In response to this, timing signals 76 and 77 synchronized with each pattern are output as shown in the lower part of the figure (E).

In the embodiments shown in FIGS. 8, 10, and 11, the scanning signal 63 is p differentiated by a differentiating circuit to obtain a waveform that is sensitive to focus, and the peak value is taken as the peak value. There is also a method of directly using the wave height value as the peak value without differentiating the scanning signal waveform. This circuit is shown in each figure by a dashed line 95. This method is resistant to noise.

In addition, as a method that is even more resistant to noise, the signal waveform is subdivided into predetermined intervals, the signal values in the subdivided subintervals are regarded as a set of the number of subintervals, and the value of the dispersion is calculated. There is also a method of regarding it as a peak value.

12 and 13 are a circuit block diagram and a signal model diagram for explaining the specific configuration and operation of the peak value detection circuit 61 in FIG. 6.

The alignment scope 4 is controlled by the focusing drive mechanism 59.
8 by a required stroke (see Fig. 6), the maximum value of the mask peak value 64 and the wafer peak value 96°97 is detected by the maximum value hold circuits 98 and 99, and the voltages 100 and 101'ft are lower by a certain value than each of them. The threshold voltages are set in threshold voltage setting circuits 102 and 103, respectively.

Next, the alignment scope 48 is moved again by the required stroke, and the previously set threshold voltage is compared with the peak values of the mask and wafer, respectively, and the alignment scope movement position when they match is stored.

This is done by using output circuits 104, 105 to create match signals 106, 107 which are sent to memory 108 on the first mask match and to memory 109 on the second mask match at the beginning of the wafer. When the second wafer matches, the alignment scope movement position is stored in the memory 110, and when the second wafer matches, the alignment scope movement position is stored in the memory 111.

The masked peak value position signal 112 is obtained by averaging the stored contents of the memory 108 and the memory 109, and the masked peak value position signal 112 is similarly obtained.
0 and the contents stored in the memory 111 to obtain a wafer peak value position signal 113. As mentioned above, focusing is performed by adjusting the mounting position error (constant value) of the two objective lenses 58 and 52 (see FIG. 6) of the alignment scope to a distance corresponding to the difference between the wafer peak value position signal and the mask peak value position signal. The process is completed by moving the wafer stage Iz direction by the distance obtained by subtracting .

Explanation about the wafer surface positioning section.

Fig. 14 is a plan view of the wafer surface positioning unit as seen from the wafer extension, Fig. 15 is a sectional view taken along the line a-a in Fig. 14, and Fig. 16 is a diagram of the groove in Fig. 15 in which the spherical seat is fitted. FIG. The wafer surface positioning section includes a holder 115° to which a non-contact displacement meter 114 is fixed, two adjustment sliders 122 that are in contact with both sides of a holder 1150, and two adjustment shafts 126. Adjustment lever 130, micrometer head 133, and drive mechanism.

This includes signal processing mechanisms, control mechanisms, etc.

The holder 115 is fixed to the holder 115 in two grooves 116 provided in the lower member of the projection optical system 7.
'Lr Two spherical seats 117 are fitted, and the holder 1 described later is
150 shaft 1 provided at both ends (referring to the left and right ends in the drawing)
20 and the projection optical system 7, four springs 123 are provided.
is suspended from the projection optical system 7 while being allowed to tilt around the spherical seat 117. Grooves 119 are provided at both ends of the holder 1150,
The aforementioned shafts 120 are inserted into the grooves 119, and each shaft 120 is provided with two and one rotatable rollers 121 (
There are two on the micrometer head side. ). Holder 11
Wedge-shaped adjustment sliders 122 are in contact with the rollers 121 at both ends of the slider 50, with their inclined portions in contact with the rollers 121. Further, the adjustment slider 122 has linear bearings 124 fixed to the projection optical system 7 on both sides (both upper and lower sides in FIG. 14).
Therefore, it is supported by the projection optical system 7 while being allowed to move in the left and right directions in the drawing.

The other end of the -4 adjustment slider 122 (the adjustment slider that is in contact with the holder 115 through the 2N roller 121) is in contact with the adjustment shaft 126. The adjustment shaft 126 is fixed to the projection optical system 7, and is inserted into the slide sleeve 127 of the pace 128 into which the slide sleeve 26 and page 127 are inserted, while being allowed to move in the left and right directions in the drawing.

On the side of the other adjustment slider 122 (the adjustment slider that is in contact with the holder 115 through one roller 121), there is a lever 130 pivotally connected to a shaft 129 fixed to the projection optical system 7.
is provided. Rotatable rollers 132 are attached to both ends of the lever 130, and one roller 132
The other adjustment slider 122 is arranged so that it comes into contact with the other adjustment slider 122. The other roller 132 has another adjustment shaft 126 provided in parallel with the above-mentioned row (adjustment slider 122 ) - (S=AI-115) - (adjustment slider 122 ) - m adjustment shaft) 126). It should be in contact with the Micrometer heads 133 are attached to the tips of the two adjustment shafts 126, respectively.

The holder 115 supports the micrometer head 133 by a spring 118 stretched between the holder 115 and the projection optical system 7 in the longitudinal direction of the holder 115 (left-right direction in the drawing).
is being energized towards. Further, the adjustment 27 Iτ slider 122 is also connected to the spring 1 stretched between the projection optical system 7.
25 toward the adjustment shaft 126 or roller 132.

The wafer surface positioning section is configured as described above, and as shown in FIG. Rotate the two micrometer heads 133 to position the adjusting shaft 126.
and 7114 by moving the slider 122 and tilting the holder 115 around the spherical seat 117 for adjustment. 134
is an A/D converter that processes the output signal of the non-contact displacement meter 114, imports it into the computer 135, and converts it to j3 as shown in FIG.
The position of the set of pulse motors 31 is controlled.

Next, the overall operation will be explained. The wafer 1 is vacuum-adsorbed onto the stage 38 of the wafer table 3, and transferred to the lower part of the alignment optical system 8 by the traveling table 6 (No. 4.6).
．． (See Figure 9). The amount of defocus is detected using the method described for the alignment optical system, and the wafer is moved and brought into focus using the method described for the wafer table. While maintaining this state, the traveling table 6 is moved to the right in FIG. 3 to move below the wafer surface positioning section 9. At this time, the detection point 47 marked with an X on the wafer 1 in FIG. 13
Calculate the position in step 5. The result is the focal plane of wafer 1 and mask 2.

When another wafer 1 is to be baked, the wafer 1 is transferred to the wafer table 3 at a certain position by a method not shown, is vacuum-adsorbed, and is moved to the right in FIG. The position of the nine X-marked detection points 47 on the surface of the sea urchin is detected by the non-contact displacement meter 114 in the section, and the traveling table 6 stops at the right end. The wafer 1 is moved by driving the /4' pulse motor 31 shown in FIG. 4 so that the plane of the detection point 47 at this time coincides with the previously calculated focus-number plane. As a method of calculating the driving amount at this time, the average value of the rows of detection points 47 on the wafer 1 in FIG. 40(c), 40(move bl, then detect point 47(a).

(b), (Calculate the average value of the floating pad 4]al
, 40(b).

40[el, then (7) of the detection point 47,
Calculate the average value of f-0, (ki) and set the floating pad 40 f
at is moved, and finally, the average value of all detection points 47 is calculated, all floating pads 40 are moved, and the average height is determined on the focal point - several plane. In addition, after the device has been in operation for some time,
Even if there is a drift of the measuring instrument, it is possible to periodically perform focusing and calibration using the alignment optical system 8.

In the embodiment, a pulse motor is used to drive the wafer table in two directions, but the invention is not limited to this. For example, a columnar piezo element can also be used. Furthermore, although the floating pad uses an air bearing, it can also be realized by a combination of a ball bush and a follower. The alignment optical system can also be realized using a mirror reflection optical system or a lens projection optical system, and although the alignment scope moving mechanism is shown as moving the entire alignment scope, it can also be realized by using a mirror reflection optical system or a lens projection optical system. It is also possible to move only the portion that reaches the light beam synthesis page 11 mirror 54 and fix the entire alignment scope.

In addition, the non-contact displacement meter is calibrated by focusing the alignment optical system, and as shown in FIG. 136 is fixed, and when the traveling table 6 passes the wafer surface positioning section 9, the reference surface 136 is measured by the non-contact displacement meter 114, and the non-contact displacement meter is used so that the measured value is used as the reference value for focusing. 114, and when there is a possibility that the height of the reference plane 136 may fluctuate, it is also possible to compare this with the focal plane calculated by the alignment optical system 8 and calibrate it.

Calibration using the alignment optical system can also be performed in a much shorter time than the conventional method using a printed and developed pattern; The frequency of calibration can be reduced, and the overall calibration time can be shortened.

3] End [[Effects of the Invention] Since the apparatus according to the present invention is constructed and operates as described above, it can bring about the following effects.

(1) With the alignment optical system of the present invention, highly accurate focusing can be performed inside the device in a short time of about 10 to 20 seconds, resulting in a significant speed-up and yield improvement.

(2) According to the alignment optical system of the present invention, since focusing can be performed frequently, calibration by parallelizing the wafer can be performed easily and in a short time, and the utilization efficiency of the apparatus is increased.

(3) In the embodiment of the wafer table of the present invention,
one set of feeding mechanisms in the direction, two sets of feeding mechanisms in the Y direction,
Three sets of transport mechanisms in two directions are provided, and between each of the six sets of transport mechanisms and the stage on which the wafer is mounted, and between each of the transport mechanisms and the stage on which the wafer is mounted, A transmission member is interposed that transmits only the force in the feeding direction of the feeding mechanism 9 and allows movement in directions other than the feeding direction, so that each of the six sets of feeding mechanisms can directly drive the stage independently. Due to this configuration, each of the six degrees of freedom of the stage can be controlled with high precision, and the positioning rigidity is high and the controllability is also good.

(4) The wafer surface positioning section of the present invention is arranged below the projection optical system, and the wafer surface positioning section is provided with a non-contact displacement meter, and the position of the non-contact displacement meter can be adjusted from the outside. It's easy.

(5) By using a non-contact displacement meter in the wafer surface positioning section of the present invention, other objects do not come into mechanical contact with the wafer surface, and the photosensitive agent coating on the wafer surface is destroyed and dust is generated. There is no fear of it happening.

Overall, the apparatus of the present invention enabled high-resolution transfer and improved product yield υ. Furthermore, frequent focusing is possible, error correction operations for parallel height adjustment to sea urchins can be performed in a short time, and high-speed, high-resolution transfer processing is possible. Furthermore, pattern alignment can be easily controlled in a stable state, and the U-33C [Uni 33C] does not damage the coating on the convex surface, making it of practical value as a projection exposure system for transferring mask patterns onto the wafer surface. Very dog-like.

[Brief explanation of the drawing]

FIG. 1 is a schematic front view of an example of a conventional projection exposure apparatus;
2 is a longitudinal sectional view of the wafer table and wafer surface positioning section of the apparatus shown in FIG. 1, and FIGS. 3 to 17 relate to an embodiment of the projection exposure apparatus of the present invention. The figures are schematic front views of different embodiments;
6 and 9 are block diagrams of different embodiments of the alignment optical system, and FIG. 7 (Al represents the pattern projected onto the scanner). 7 [Bl and (C1 is a scanning signal waveform diagram, FIG. 8, FIG. 10, and FIG. 11 (N is a circuit block diagram of each different embodiment of the peak value detection circuit, and FIG. 11 [Bl, (C1 and ■) are pattern diagrams projected on the scanner, Figure 11 (E) is a scanning signal waveform diagram, Figure 12 is a circuit block diagram of the peak value detection circuit,
Figure 3 is a signal model diagram in the peak value detection circuit, Figure 14 is a plan view of the 34-lamp wafer surface positioning section as seen from the wafer side, and Figure 1
Figure 5 is a sectional view taken along the line a-a in Figure 14, and Figure 16.
The figure is a sectional view taken from arrow b in FIG. 15 of the groove into which the spherical seat is fitted. 1... Wafer, 2... Mask, 3... Wafer table, 4... Mask table, 5... Stone surface plate, 6...
... Traveling table, 7... Projection optical system, 8... Alignment optical system, 9... Wafer surface positioning unit, 10
...Exposure light source, ah...Heas member, 29, 30, 3
1...Pulse motor, blade...stage, 40, 4
4, 46... Floating pad, 47... Detection point, 48
... Alignment scope, 52.58 ... Objective lens, 56 ... Scanner, 59 ... Drive mechanism, 114
...Non-contact displacement meter, 115...Holder, 122...
・Adjustment slider, 126...Adjustment shaft, 130・
...Adjustment lever, 133...Micrometer head,
136...Reference surface. Representative Patent Attorney Tadashi Akimoto Figure 4 Figure 9 Figure 5 Figure 1o Figure 11 (A)

Claims (1)

[Claims] 1. The wafer placed on the wafer table is positioned under the wafer surface positioning section, together with the projection optical system that projects and images the mask/f-turn onto the wafer surface. In a projection exposure apparatus having means for positioning and an alignment optical system for detecting focal position deviation of the projection optical system from the wafer surface, the wafer table is adjustable in height direction and parallelism, and a wafer surface positioning section is provided. A non-contact displacement meter is provided, and the non-contact displacement meter is linked with an adjustment unit that adjusts the height direction and parallelism of the wafer table through a control circuit, and the alignment optical system is used to adjust the height and parallelism of the wafer table. Converts the light of A projection exposure apparatus characterized in that the wafer surface is made to coincide with the image forming plane of the mask pattern by correcting the position. 2. The wafer table has a pace member, one set of feeding mechanisms provided on the pace member in the X direction, two sets of feeding mechanisms provided in the Y direction perpendicular to this, and two sets perpendicular to the X and Y directions. 9 and 6 sets of stages on which the wafer is placed, movable in the X and Y directions, and adjustable in the height direction and parallelism as described above, by means of three sets of feeding mechanisms provided in the directions. A transmission member is interposed between each of the feeding mechanisms and the stage to transmit only the force in the feeding direction of each feeding mechanism and to allow movement in the feeding direction, and each feeding mechanism is independent. 2. A projection exposure apparatus according to claim 1, wherein said stage can be directly driven by said stage. 3. The alignment optical system aligns the i of the mask and wafer.
+A photoelectric scanning microscope for detecting a turn signal, means for moving the photoelectric scanning microscope in the optical axis direction of the projection optical system with respect to the wafer, and each pattern on the mask and the sea urchin with respect to the moving position of the photoelectric scanning microscope. 3 (means for detecting the position of the peak value of t), and the defocus of the projection optical system is detected according to the distance of the difference between the positions indicating the respective peak values. 4. The projection exposure apparatus according to claim 1, wherein the wafer surface positioning section is supported by a projection optical system. 5. The projection exposure apparatus according to claim 1, wherein the wafer surface positioning section is supported by a projection optical system. A plurality of contact displacement meters are arranged in a line on the wafer surface positioning section, and in combination with the movement of the traveling table on which the wafer table is mounted, the non-contact displacement meters are provided two-dimensionally distributed over the wafer. 2. The projection exposure apparatus according to claim 1, wherein the projection exposure apparatus is configured to measure the height of the projection exposure apparatus.