JPS60150629A - Photoelectric detector - Google Patents

Abstract

PURPOSE:To improve the signal detection ratio by a method wherein photoelectric elements correspond to any detected patterns in the diffractive direction to be divided for arrangement in the radial direction so that specified signals may be detected by means of selective combination of each photoelectric element. CONSTITUTION:A photodetector 18 is composed of the photoreceiving surfaces 18b1-b4, 18c1-c4, 18e1-e4 respectively divided to receive signals independently. When mark patterns 12a, 13a, 12b are detected, the sum of signals transmitted from the photoreceiving surfaces 18b1, 18c1, 18d1, 18e1, 18b3, 18c3, 18d3, 18e3 will become the mark signals (A channel) while the sum of signals transmitted from the photoreceiving surfaces 18b2, 18c2, 18d2, 18e2, 18b4, 18c4, 18d4, 18e4 will become the noise signals (B channel). Fig. (a) represents the output if there is a dirt 42 on the scanning line when patterns on a mask and a wafer are scanned, while Figs. (b) and (c) respectively represent the outputs of A channel and B channel. On the other hand, Figs, (d)-(f) represent the signals passing through the differential amplifier processing A-B channels to restrain any noise due to a dirt signal from sounding while augmenting pattern S/N.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a photoelectric detection device for relative positioning of two objects such as a mask and a wafer in a semiconductor printing device, or a positioning device for processing machines such as semiconductor devices. ,
In particular, this photoelectric detection device is effective for detecting signals where the surface of the object to be detected is not flat but uneven, or where the p-th diffraction pattern is known.

[Prior art]

As a conventional photoelectric detection device, JP-A-53=91.7
There is a device according to the present applicant disclosed by No. 54 (Scanning Photodetection Device). In this device, a light shielding member is arranged to remove specularly reflected light from a flat object surface and receive only necessary pattern scattered light. Is the size of this light shielding member as large as possible to block specularly reflected light?
Or set it slightly larger than that.

However, if the surface of the object is not flat but uneven, scattered light is generated in areas other than the predetermined detection marks (2) and cannot be blocked by a light shielding member. Problems such as deterioration of accuracy or failure to detect occurred.

Also, as a conventional photoelectric detection device, JP-A-53-13
There is a device according to the applicant disclosed by No. 5,654. In this device, the detection light beam is divided into two using a light beam splitting means, each detection light beam is selectively passed through a predetermined spatial filter for 1 hour, and these two transmitted lights are received by another light receiving element. The configuration is such that the electrical signal is converted into an electrical signal, and the electrical signal is processed to selectively detect pattern aunts.

However, according to this configuration, since the detection light flux is divided into two and detected, the photoelectricity of the detection light flux is halved in the light receiving element, and this is not true for patterns with low reflectance or patterns with a low one-level difference between the wafers. The drawback was that sufficient detection was not possible. Furthermore, if the central axes of the plurality of spatial filters are not precisely aligned with the central axis of the detection light beam, there is a problem that the contrast of the detection light beam decreases and the detection accuracy deteriorates.

[Purpose of the invention]

The present invention has been proposed in view of the drawbacks of the conventional examples mentioned in Section 2, and is a photoelectric detection device or spatial filter axis a-alignment device that makes it possible to obtain a detection signal with an optimal S/N ratio and contrast. The object of the present invention is to provide a photoelectric detection device that eliminates work and makes it possible to obtain a predetermined detection signal by making the filter range of a spatial filter variable.

〔Example〕

Hereinafter, a photoelectric detection device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a principle diagram of a signal detection system of an automatic mask and wafer alignment apparatus to which a photoelectric detection device according to an embodiment of the present invention is applied. 1 is a laser light source, 2 is a condenser lens.

6 is a rotating polygon mirror, 4 is a relay lens, and 5 is a beam splitter for splitting the light into an optical system for visual inspection of 22 or less.
76 is a field lens, 7 is a beam splitter for splitting light into 5 optical systems of 14 or less light, 18 is a relay lens, 9 is for guiding light from illumination optical systems for visual observation from 19 to 21. The beam splitter 210 is a pupil of the objective lens 11, 12 is a mask, and 16 is a wafer. The conjugate relationship of the laser beam itself is as follows. That is, the Lehner tip is focused at a position 30 by the -tan condensing lens 2. The spot diameter of the laser beam at the position 60 is determined by the diameter of the incident laser beam and the focal length f2 of the condenser lens 2. Assuming that the laser beam is uniformly distributed within the radius, the diameter d of the laser spot is expressed as d = 2.44λ. The laser beam diverging from the position 60 is reflected by the rotating polygon mirror 6, passes through the relay lens 4, and -
An image is formed at a point 62 near field lens B.

Further, the light passes through the relay lens 8 and the objective lens 11 and is imaged at 64 positions corresponding to the mask and wafer surfaces. Therefore, in Figure 1, 30.32.34 is conjugated to beni. The diameter Φ of the spot 64 that actually scans the mask and Ueno surface is expressed as Φ = axd, where a is the imaging magnification of 60 to 64. The scanning spot diameter can be changed by changing d. This can be achieved by changing the beam diameter of the light or the focal length f2 of the lens 2. Also, if you only want to enlarge the scanning spot, you can change the condenser lens 2. This can also be achieved by intentionally moving the position of , and defocusing the laser beam at position 60. Generally, it is desirable to select the diameter of the scanning spot appropriately depending on the line width of the target pattern, but the system shown in Figure 1 The laser beam focused at the position 64 scans over the mask and wafer surface as the rotating polygon mirror 6 rotates.

In addition to the conjugate relationship of the scanning beam on the actual object plane as explained above, the image formation relationship of the pupil of the optical system shown in FIG. 1 is also important. The pupil of the objective lens 11 is indicated by 10, but 10
A point 66 on the optical axis, which is the center point of , and a reflection point 61 of the rotating polygon mirror 6 are conjugate with each other. That is, the arrangement shown in FIG. 1 is equivalent to placing a rotating polygon mirror exactly at the position of the pupil 10 in terms of the incidence of the laser beam on the objective lens.

A telecentric objective lens is used when observing reflective objects such as wafers. Objective lens 11 in FIG.
is a telecentric arrangement, that is, the pupil 10, which determines the light beam passing through the optical system, is placed at the front focal position of the objective lens 11.

Figure 2 shows this situation. The center 63 of the pupil position 10, which is the front focal point of the objective lens 11, is conjugate with the laser reflection position 61 of the rotating polygon mirror B as described above, so it acts as if a scanning beam were generated from there. The principal ray, which is the center line of the scanning beam, passes through the front focal point 66 of the objective lens, so after passing through the objective lens 11 it becomes parallel to the optical axis and enters the mask and wafer perpendicularly. If the area hit by the scanning beam is flat, the incident light will be reflected and return to the position of the river 66. On the other hand, if there is a pattern where the traveling beam hits, the light will be scattered at the edges of the pattern boundaries and will not return to its original location. That is, when the scattered light is captured by the objective lens 11 and passes through the pupil 10, it no longer passes through the center 66 of the pupil but passes toward the edge of the pupil.
It becomes f. This fact is quite trivial; it is nothing more than the fact that scattered light and non-scattered light are spatially separated in the uptake. FIG. 2 shows this separation. That is, if the scanning beam scans the object plane from left to right, the light is not scattered until it hits a certain portion 65 of the pattern and is reflected back to the original pupil 19 [19]. When the light hits the pattern 65, it is scattered and passes through the optical path shown by the dotted line.
11! It does not return to its original position on 10.

The area occupied by the unscattered light at the pupil 10 is the same as the diameter of the scanning laser beam. In order to effectively capture scattered light, the effective diameter of this non-scattered light is set to be sufficiently small compared to the diameter of the pupil, and the ratio of this diameter is usually set in the range of 1 to 0.7. 11 is preferred.

Returning to FIG. 1 again, consider the photoelectric detection optical system that separates from the beam splitter 7 and reaches the photodetector 18. In the figure, 14 is a lens that forms an image of the pupil 10 of the objective lens 11, and 15 is a filter that filters light for photoelectric detection and substantially cuts other wavelengths, such as wavelengths used in the viewing optical system.

The position of the photodetector 18 is where the image of the pupil 10 is formed by the pupil imaging lens 14. Therefore, the pupil 10° photodetectors 18 are in a conjugate relationship with each other. This photoelectric detection system outputs an output of 1↓ only when the scanning spot approaches the detection object. Therefore, by observing the output in time, it can be seen that a pulse-like signal is generated when the scanning beam hits an edge, and a step-like signal is obtained when the scanning beam hits the sensing object. If this pattern is a signal from an alignment mark on the mask and wafer, the relative positional deviation between the mask and wafer can be detected from this signal. Auto-alignment is performed by not moving the relative positions of the mask and wafer using a drive system (not shown) so as to correct the detected deviation.

Further, a step-like signal generated when the scanning beam hits a detection object is used as a synchronization signal.

In FIG. 1, illumination systems 19 to 21 and observation systems 22 and below are provided for visual observation. 19 in the figure is a light source for illumination,
A condenser lens 20 functions to form a light source image on the pupil 10 of the objective lens 11.

Reference numeral 21 denotes a filter that has the function of cutting off light in the wavelength range to which the photoresist is sensitive. On the other hand, reference numeral 22 designates an erector 226 which rotates the image in the normal direction, and a filter which cuts radar wavelengths and transmits wavelengths for visual observation, and reference numeral 24 designates eyepiece lenses.

On the other hand, as a mark suitable for spot scanning by RETSU, for example,
There is an example of this in ``Optical Device'' filed under No. 9. This mark is a mark like the one shown in FIG. 3, which has a skewer for detecting X and Y deviations in one direction line scanning. Figure 6 (
al is a pattern for a mask (or wafer), (b) is a pattern for However (or a mask), and (C) is a state when both are aligned. Note that the dotted line in Figure C1 is the locus of the scanning laser beam.

One of the problems with this photoelectric detection method is dust. In other words, since this photoelectric detection system detects scattered light, if there happens to be an object 14 that scatters light, such as dust, in the area targeted for photoelectric detection, the scattered light from this dust will also be picked up as a signal. . Dust may be attached to the wafer or inside the scanning optical system. Dust adhering to wafers is a factor that must always be taken into consideration. Detected light from other than the pattern generated in this way is a so-called false signal, which is not only undesirable but also causes malfunction.

The present invention aims to remove unwanted detection light from other than the pattern such as the above-mentioned dust or diffused reflection from the surface of the detection object, and specifically, it divides the light-receiving surface of the photodetector. It is an attempt to utilize the means. Here, in order to utilize the means of dividing the light-receiving surface of the photodetector, consider the distribution of light observed at the photodetector 18 of the photoelectric detection section in FIG. 1. In the explanation so far, scattered light has been understood as a phenomenon of scattering from pattern edges, but in essence, this is nothing but a type of diffraction phenomenon. Therefore, the light becomes a skewer that is scattered in the j direction depending on the directionality of the pattern (t). In the case of an aligned non-mark as shown in Fig. 6, the so-called diffraction pattern of the scattered light observed at the position of the photodetector 18 is shown in Fig. 4(a) and (bl). A skewer extending in a direction perpendicular to the direction of
, 13a, , 12b, as shown in Fig. 4(b).
is the scattered light from 12C216b and 12d in FIG. On the other hand, scattered light from irregularly shaped substances such as dust does not show any particular directionality at the light shielding plate and spreads uniformly. The situation is shown in FIG. 4(C).

In both Figures 4 (al, (b), and fCl), the black dot in the center is the area due to non-scattered light, and the other shaded areas indicate the area where the light is spreading.The outer circle is the area where the light is spreading. shows the effective diameter of

The present invention utilizes the difference in scattering from the patterned portion and the non-patterned portion at the photodetector position. Therefore, the present invention is characterized in that the light receiving surface of the photodetector is divided into a pattern detection light receiving surface and a scattered light receiving surface. The roles of these light-receiving surfaces are switched depending on the direction of the detection pattern. Here, the signal obtained from the pattern detection light receiving surface is called a mark signal, and the signal obtained from the scattered light receiving surface is called a noise signal.

FIG. 5 is a schematic top view showing an embodiment of such a photodetector. The 18 photodetectors are each divided into light receiving surfaces 18a and 1 from which signals are collected independently.
8b+, 18b2, 18ba, 18b+.

18c+, 18c2, 18cs, 18c4, 18d+,
18d2゜18d3.18d4, 18e+, 18e
2.18 (13, 1f3e4).The central light receiving surface 18a receives the IE reflection 9 of the optical scanning beam.

As a result, it is recognized that the optical scanning beam is scanning the detection area 1, and the post-processing circuit generates a signal in the synchronous area, and at the same time measures the reflectance of the detected object (j↓ is possible. When detecting the mark patterns 12a, 13a, 12b in the figure, "□light surfaces 18b+, 18c+, 18d"
+, 18e+.

The sum of the numbers obtained from 18bs, 18c3, 18d3, and 18e3 becomes a mark signal, and the light receiving surfaces 18b2, 1
8c2.

18d2.18e2.18b4.18+! 4, 18d
The sum of the signals obtained from 4.181!4 becomes the noise signal. Next, mark patterns 12c, 13b, 12 in FIG.
If d is detected, then 18b2, 18C! 2.
18dz.

18ez, 18b4, 18C4, 18d4, 18e4
The sum of the signals obtained from is the mark signal, and the light receiving surface 1
8b+.

18c+, 18d+, 18e+, 18bs, 18c3,
18ds.

The sum of the signals obtained from 18e3 becomes the noise signal.

When mark signals and noise signals are detected in this way,
It is possible to detect synchronized noise (i2) with approximately the same amount of light scattered by dust etc. contained in the mark signal. Therefore, by subtracting the noise signal from the mark signal, false detection due to dust etc. will be eliminated, and such influence can be completely eliminated. Here, the side where mark No. 11f is outputted is called the A channel, and the side where the noise signal is outputted is called the B channel. Therefore, by detecting the synchronization signal and counting the number of pulses detected by the post-processing circuit, it is easy to know which direction the light receiving surface is for the A, V or B channels. can.

Next, an ejection processing system according to an embodiment of the present invention will be explained. FIG. 6 is a diagram No. 11 for explaining the signal processing. FIG. 6(a) shows the positional relationship when the patterns on the mask and the wafer are scanned. In this figure, the one-dot chain line indicates the rate-to-scanning light, and the arrangement is exactly the same as that in FIG. 6(C) except for J↓ where dust 42 is placed on the scanning line.

FIG. 6(b) shows the output of the A channel, and FIG. 6(C) shows the output of the B channel. Since the A channel is a "pattern S/N ratio J" and the B channel is a "dust" detection channel, the output is as shown in the figure.

FIGS. 6(d) to 6(f) show three aspects of the signal that has passed through the differential amplifier 2g (not shown) that performs the calculation (A-B). (dl
is the garbage signal of the A channel and the garbage signal of the B channel 41
If No. 1 successfully canceled J once, (e) is B Taeyang Lee's garbage 14, if No. 1 was larger, if
) is the case where the garbage on the A channel (lj is larger and cannot be completely canceled. (dl~(f))
There are various factors that determine which one will be, such as the characteristics of dust scattering, applying a magnification to one or both Nos. 413 during differential amplification, or using the difference in IW sensitivity of the photodetector, etc. -4 has already been determined. I can't do that. However, compared to the output of (b) in which only non-scattered light is simply cut, the outputs (a) to (f), which are outputs after tracing the differential amplifier, suppress noise and improve the pattern S/N. The ratio is crystallizing.

Next, another problem with photoelectric detection is that if the surface of the target area for photoelectric detection has unevenness, the scattered light generated by the unevenness will be picked up as a signal, but the detected light from other than the pattern will be picked up as a signal. detects r+! because the contrast decreases and the S/N deteriorates. This results in a decrease in r degree and a decrease in signal detection rate. Considering the distribution of scattered light from unevenness on the surface of the light weight detection target area observed at the photodetector 18 in FIG. 1, this scattered light shows a special directionality at the detector 18. It shows a uniform spread.

Figure 4(d) shows a state where there are some irregularities on the surface of the detection object, and if the irregularities are slightly larger than that, Figure 4(el, history(''
- When the unevenness becomes large, it becomes as shown in FIG. 4(f). In this way, the spread of scattering) t changes in response to the unevenness of the surface of the detection object. In Figure 4 (dl, (cl, and f), the black dot in the center is the area due to non-scattered light, and the outer shaded area shows the area where the light is spreading. Also, the outer circle is the area where the light is spreading. The effective diameter of this optical system is shown.

The present invention focuses on the difference in the spread of light at the position of the photodetector 18. Therefore, in the present invention, 4
The light-receiving surface of the photodetector extending in the direction is divided into four light-receiving surfaces in each direction at equal distances from the center.

For signals from the light-receiving surfaces in each direction, light-receiving surfaces equidistant from the center are selected in response to differences in patterning (differences in signal levels due to the two types, and spread of scattered light from the surface of the detection object). After the respective output signals of the light-receiving surfaces are combined, they are outputted to a signal processing circuit as a signal with the best contrast and S/N ratio.

FIG. 7 is a block diagram of a signal processing circuit according to an embodiment of the present invention. Light-receiving surface 1 in the center of photodetector 18
When the detection scanning beam 8a detects that the detection area is scanned, it outputs a signal to that effect to the amplifier 51.

After the amplifier 51 amplifies the signal, the voltage comparator 58 and the A/D
Output to converter 54. The signal from the light receiving surface 18a output to the A/D converter 54 is converted into a digital signal and sent to the arithmetic processing circuit 57. Arithmetic processing circuit 5
7 consists of an arithmetic processing section, a memory section, and an interface section that handles human output signals. A/D converter 5
4 to the arithmetic processing circuit 57, the arithmetic processing circuit detects its magnitude, calculates and determines the threshold hold level, and then outputs it to the D/A converter 56. Ru. The threshold voltage output from the D/A converter 53 is used as a reference voltage for the voltage comparator 58. The voltage comparator 58 compares this reference voltage with the output of the amplifier 51 by the second scanning beam, and outputs a signal while the detection scanning beam scans the detection area. This output signal is shown in FIG. 8(d), and this output signal is used as a synchronizing signal for time measurement of a pattern signal, which will be described later.

Each light receiving surface 18b+, 18c+ of the photodetector.

18d+ and 18e+ are each selection switch 50b++5
0c+.

It is connected to the signal synthesis circuit 52 through 50dI and 50eI. Similarly, other light receiving surfaces are also connected to the signal combining circuit 52 via corresponding selection switches. Each selection switch is turned on or off depending on the output of the arithmetic processing circuit 57.
The state becomes FF, and each light-receiving surface is selected. The signal synthesis circuit 52 has an amplifier for each light receiving surface, and has an adder and a subtracter that independently add or subtract signals from each light receiving surface according to the output of the arithmetic processing circuit 57, and combines them. It is possible to output the signal to the voltage comparator 59 and the A/D converter 56 as one output.The arithmetic processing circuit 57 first outputs an ON output to the all selection switches, and outputs the signals of all the light receiving surfaces as a signal. The synthesis circuit 52 is operated manually.

Next, the oil 1-processing circuit 57 transmits the light receiving surfaces 18b+, 18c+, 18d+, 18e+ to the signal synthesis circuit 52.
, 18b3°18cs, 18d3.18es are added, and the light receiving surfaces 18b2, 18c2.18d2.
18e2.18b4.18(!4゜18d4,18e+
Add the command A1 to subtract the number 11 from the number.

()j The electric synthesis circuit 52 outputs the added and subtracted output to the A/D converter 56 and the voltage comparator 59. The arithmetic processing circuit 57 detects the magnitude of this output signal through the A/D converter 56, calculates and determines the threshold bold level, and outputs it to the D/A converter 55.

The voltage comparator 59 uses human power from the signal synthesis circuit 52 and the D/A
The thread hold voltages from the converter 55 are compared and a pulse output corresponding to the pattern signal is output.

Then, the arithmetic processing circuit 57 counts the number of pattern signals of the voltage comparator 59 from the time when the synchronization signal of the voltage comparator 58 is generated, and after counting three pattern signals and passing the third pattern signal, the signal is synthesized. A command signal for addition and subtraction is given to the circuit 52. That is, light reception 1jjT18b2, 18c2
．． 18d2, 1882, 18b4゜18c4, 18d4
, 18e4, and the receiving peak 1isb+,
18c+, 18d+, 18e+, 18ba, 1
The signals from 8c3°18d3 and 18e3 are subtracted.

As a result, the output of the signal synthesis circuit 52 obtained is shown in FIG. 8(b). The addition/subtraction processing of the signal synthesis circuit 52 and the combination of light receiving surfaces are switched and repeated at the rising edge of the synchronization signal and at the time of three pattern signals, as described above.

By the way, the signal in FIG. 8 (b1) contains a lot of scattered light due to the unevenness of the detection surface. ) are stored in the storage section of the arithmetic processing circuit, and the pedestal signal P1 and pattern signals S+, S2, Ss, S4 are placed in the -center.

Compute S, , S,. When the pattern signal is large or when the pedestal signal P1 is larger than a certain value,
The arithmetic processing circuit 57 is located on the inner light receiving surface 18bI.

Selection switch 50b+, 50b2, 50b3, 50b4 to disconnect the signals of 18b2, 18b3, 18b4
An OFF signal is sent to the signal to prevent it from being combined by the signal combining circuit 52. The result is obtained (No. 6 synthesis circuit 52
The output is as shown in Figure 8 (C1).If the inner light-receiving surface of the detector 18 is separated as shown in Figure 8 (C1), the pedestal signal P2 will be greatly reduced, but the pattern signal S
r, Ss, Sg, SIo, Str, S
I2 also decreases underwear. In this way, the arithmetic processing circuit 57 sequentially separates the light-receiving surfaces of the photodetector, fixes the light-receiving surface combination a that provides the best contrast when the pattern ratio is above a certain level, and at the same time reduces the pattern signal level. Correspondingly, the thread hold voltage to the voltage comparator 59 is also changed. Next, the arithmetic processing circuit 57 selects the outer light receiving surfaces 18e+, 18e2, 1 of the photodetector 18 while checking that the contrast does not deteriorate beyond a certain level.
The light receiving surface is separated from the combination of 8es and 18e+, and the separation of the light receiving surface is stopped one step before the contrast deteriorates beyond a certain level. When the operation of separating the light from the outside is performed, there are cases in which no effective light beam is generally incident on the light-receiving surface on the outside, but even in such a case, a dark current flows. This is because this dark current is a noise signal and substantially reduces the S/N ratio. By appropriately combining the light receiving surfaces of the photodetector 18 in this way, the best contrast, the best S/N, and the best pattern signal can be obtained. As a result, a signal with a good detection rate and high detection accuracy can be obtained.

Figure 8 (al) shows the positional relationship when scanning the patterns on the mask and wafer, and the dotted line shows the laser scanning. Figure 8 (b) shows when all light-receiving surfaces are activated. (C1 is a detection signal diagram when the light-receiving surfaces are optimally selected and combined, (d
) is a synchronization signal diagram.

〔Effect of the invention〕

As explained above, according to the present invention, the photoelectric elements are arranged corresponding to the diffraction direction of the detection pattern and are also divided in the radiation direction, and a predetermined signal is detected by selectively aligning each photoelectric element. It is possible to obtain a sufficiently large detection signal level by using the following method.

In addition, since there is a single cod detection route, the equipment configuration is 13.
” is simplified. Furthermore, complicated positioning such as optical axis alignment of a plurality of Kusama filters is not required, and adjustment is simple. Furthermore, since each nine-dimensional element is on the same plane, the sensitivity among the elements is uniform.

Further, according to the present invention, a plurality of divided light receiving surfaces can be selected as desired so as to obtain a detection signal with a high contrast and an optimum S/N ratio, which improves detection accuracy and improves detection accuracy.
It is possible to improve the detection efficiency.

Furthermore, according to the present invention, the photoelectric element is divided into a part that detects the pattern signal of the detection object and a part that detects that the detection area surface is detected, and the photoelectric element is divided into a part that detects the pattern signal of the detection object and a part that detects that the detection area surface is detected. It can be used as a thread hold voltage for the synchronous signal 5.1 and 2.5, and has the effect of shortening the detection time and making the device configuration simple.

[Brief explanation of the drawing]

Fig. 1 is a principle diagram of a signal pressure detection system of an automatic mask and wafer alignment device using a photoelectric detection device according to an embodiment of the present invention, Fig. 2 is a diagram showing the action of a telecentric objective lens, and Fig. 6 is a diagram showing the operation of a telecentric objective lens. The figure is a diagram showing an example of marks used in the automatic alignment device. FIG. 4 is a diagram showing the diffraction pattern from the mark and the distribution of scattered light from the detection object surface, FIG. 5 is a diagram showing the photodetector according to the embodiment of the present invention, and FIG. A signal diagram for explaining the signal processing system according to the embodiment, FIG. 7 is a block diagram of the signal processing circuit according to the embodiment of the present invention, and FIG. 8 is a detection mark pattern and light receiving surface according to the embodiment of the present invention. 1. This is a diagram showing detection signals and synchronization signals before and after selection of 1.
4... Lens 3... Rotating polygon mirror 5.7.9... Beam splitter 10... Pupil of objective lens 11 11... Objective lens 12... Mask 16... Wafer 15.21 .23...Filter 18...Photodetector 19...Illumination light source 65...Pattern depression 51...Amplifier 52...A, i-synthesizing circuit 53.55...D/A converter 54 .56... A/D converter 57... Performance processing circuit 58.59... Voltage comparator. 2nd Figure 1'(l) 3rd ffl (a) (b) (c) (d) (e) (f) 4th Figure 5

Claims (1)

[Claims] A plurality of light cannon elements arranged corresponding to the directionality of the diffracted light are capable of independently receiving diffracted light from a plurality of detection patterns arranged in different directions, and output signals of the plurality of photoelectric elements are provided. A photoelectric detection device comprising means for performing arithmetic processing and calculating a predetermined detection pattern signal.