JPS6211137A - Apparatus for inspecting foreign matter - Google Patents

Abstract

PURPOSE:To enhance an S/N ratio, by inclining the light receiving areas of photoelectric converter elements with respect to the arrangement direction thereof and arranging the same so that adjacent light receiving areas continue when said areas are looked from the direction crossing the arrangement direction at right angles. CONSTITUTION:The light receiving areas 90B of the photoelectric converter elements 90C of a light receiving element 90 receiving the reflected light from a surface (wafer) to be inspected to convert the same to an electric signal re inclined with respect to the arrangement direction thereof. The photoelectric converter elements 90C are arranged at such an arrangement pitch that adjacent light receiving areas 90B substantially continuous when said elements are looked from the direction crossing said arrangement direction at right angles. The visual field on the the wafer of each light receiving area 90B is moved to a specific direction and the wafer is observed all at one by a plurality of visual fields closely arranged in the direction crossing a scanning direction at right angles.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application in Industry-1-] The present invention relates to a foreign matter inspection device for detecting foreign matter on a planar comparison table surface such as the surface of an LSI wafer.

[Prior art] As a foreign matter inspection device for LSI wafers, a light beam is irradiated onto the wafer, the reflected light from the wafer is received by a light receiving element and converted into an electrical signal, and the wafer is inspected based on this electrical signal. There is a type that determines the presence or absence of foreign objects.

In this type of conventional wafer foreign matter inspection equipment, one photomultiplier is installed as a light receiving element, and in order to narrow down the field of view on the wafer, the reflected light from the wafer is made to enter the photomultiplier through a slit. It has become. By rotating the wafer and moving it in the radial direction, the field of view of the photomultiplier is moved in a spiral manner, and the inspection is performed while scanning the wafer surface in a spiral manner.

[Problems to be Solved] The output signal of the photomultiplier includes, in addition to signal components related to foreign matter, background noise determined by the surface condition of the wafer. S of that signal
In order to increase /N by 1 - and to detect minute foreign matter in 11 steps, it is necessary to make the field of view of the photomultiplier on the wafer surface as small as possible. In the conventional device, the field of view is narrowed down by reducing the aperture of the slit.

However, in the conventional apparatus, the photomultiplier has one field of view, so in order to thoroughly inspect the wafer surface, the pitch of the scanning lines (trajectory of movement of the field of view) must be made small, which significantly increases the inspection time. The problem was that it was increasing.

Therefore, the inventor proposed that one method to solve such problems is to use a light receiving element in which a plurality of photoelectric conversion elements are linearly arranged, such as a bin photodiode array.
We considered arranging the plurality of fields of view in a direction perpendicular to the scanning direction and observing the wafer surface in lk rows using the plurality of fields of view.

However, in such a conventional light-receiving element, there is a fairly wide gap between the light-receiving areas of each photoelectric conversion element when viewed from a direction perpendicular to the arrangement direction of the optical 7u conversion elements. When spiral scanning is performed,
The empty space between the fields of view will not be inspected.

As a way to deal with this, it is also possible to arrange two light receiving elements in parallel with a slight shift in the arrangement direction of the photoelectric conversion elements, and to position the field of view of another light receiving element between the field of view of one light receiving element. However, there are problems in that precise adjustment of the relative positions of the light receiving elements is troublesome and positional errors are likely to occur.

Another method is to arrange the light-receiving elements obliquely so that the array of fields of view is inclined at a large angle with respect to the scanning direction, thereby reducing the space between the fields of view, or making the fields of view substantially continuous. However, since the position of each field of view, that is, the position of the inspection point, differs significantly from field to field, it is necessary to perform processing such as correcting the position of the detected foreign object according to the corresponding field of view. In the case of helical scanning, the position must be compensated for both the radial coordinates and rotation angle of the wafer, which poses problems such as the process becoming quite complicated. This also applies when two light receiving elements are used.

[Objective of the Invention] The object of the present invention is to solve the problems of the conventional foreign matter inspection device as described above, and to solve the problems that occur when using a conventional pin photodiode array.
The purpose of the present invention is to provide a four-object inspection device.

[Means for Solving the Problems] According to the present invention, in order to achieve the target, a light beam is irradiated onto the valley surface to be inspected, and reflected light from the surface to be inspected is received. In the foreign matter inspection device that receives the light with an element γ, converts it into an electrical signal, and determines the presence or absence of foreign matter in the valley surface to be inspected based on the electrical signal, the light receiving element r has a plurality of photoelectric conversion elements arranged linearly. The light-receiving area on the light-receiving surface of each of the photoelectric conversion elements is tilted with respect to the direction of the arrangement, and the adjacent light-receiving areas are substantially continuous when viewed from a direction perpendicular to the direction of the arrangement. The photoelectric conversion elements are arranged at an arrangement pitch such that the field of view of each light-receiving area on the surface to be inspected is moved in a specific direction, and the direction of the arrangement is such that the field of view of the light-receiving area on the surface to be inspected is The direction is selected to be arranged in a direction substantially orthogonal to the specific direction.

[The field of view of the valley surface to be inspected in each light-receiving area of the light-receiving element] is lined up without gaps in the j direction (perpendicular to the scanning direction), and the valley surface to be inspected is observed all at once by a group of these fields of view.

Therefore, each field of view is narrowed down for 1 minute to detect foreign objects El 4+'+
It is possible to increase the signal-to-noise ratio and shorten the inspection time.

In addition, it is possible to place the light-receiving element at an angle with respect to the scanning direction,
Since there is no need to arrange even a plurality of them, the problems that would occur in such a case do not occur.

[Embodiment Code] An embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a simplified schematic diagram showing the configuration of the optical system and other parts of the wafer foreign matter inspection apparatus according to the present invention. In this figure, IO is an X stage supported on a base 12 with nJ sliding ability in the X direction.

A screw 16 directly connected to the rotating shaft of a stepping motor 14 is screwed into the X stage 10, and by operating the stepping motor 14, the X stage 10 can be moved forward and backward in the X direction. 18 is a linear encoder that generates a code signal corresponding to the position X in the X direction of the X stage lO.

A Z stage 20 is attached to the X stage 10 so as to be movable in the Z direction. 19 is a stepping motor for moving the Z stage 20 in the Z direction, and is fixed to the X stage 10. Although omitted in the diagram,
An eccentric cam is attached to the rotating shaft of the stepping motor 19, and a cam follower that engages with this cam is provided on the Z stage 20 side. When the stepping motor 19 is operated, its rotation is transmitted to the Z stage 20 via the eccentric cam and the cam follower.
2nd stage 20 is todo.

Additionally, a wafer 3 as an object to be inspected is mounted on the Z stage 20.
A rotary stage 22 on which 0 is placed is rotatably supported. Here, as the wafer 30, a wafer with a blank film, a mirror wafer, or a wafer with a pattern can be set and inspected.

This rotation stage 22 is connected to a DC motor 24, and is rotated by operating the DC motor 24. This DC motor 24 has a built-in rotary encoder that outputs a code signal corresponding to its rotational angular position θ.

Note that the wafer 30 is positioned and fixed on the rotation stage 22 by negative pressure suction, but means for this purpose are omitted in the figure.

This wafer person inspection apparatus automatically inspects the wafer 301 for foreign substances using polarized laser light, and the S-polarized laser light is irradiated onto 1uii (test surface) of the wafer 30. For that purpose, S-polarized laser oscillators 3s, 3
8 is provided. Each S polarization laser oscillator 36.38
is a semiconductor laser oscillator that generates S-polarized laser light of a certain wavelength, for example, a wavelength of 8300 angstroms.

The S-polarized laser beam is irradiated once from the Y direction onto the H surface of the wafer 30 at an irradiation angle φ of approximately 2 degrees.Since the irradiation angle is small in this way, the S-polarized laser beam with a circular cross section is When irradiating the wafer, the spot on the wafer becomes long, making it impossible to obtain an irradiation density of 1 minute.
An lindrical lens 44.46 is placed in front of the polarized laser oscillator 36°38, and S-polarized laser oscillation Z436.3 is performed.
The S-polarized laser beam with an almost circular cross section emitted from the Z
The beam is narrowed down to a flat cross-sectional shape and then irradiated onto the wafer.

Here, in the case of a wafer with a blank film without a pattern (or a mirror-finished wafer), if there is no foreign matter in the irradiation spot, the S-polarized laser light will be almost specularly reflected and will not be reflected in the Z direction. If there is, it causes diffuse reflection and is also reflected in the Z direction.

On the other hand, in the case of a patterned wafer, the reflected laser beam of the S-polarized laser beam irradiated onto the wafer is also reflected in the Z direction if a pattern exists within the irradiation spot.
Since the surface of the pattern is microscopically smooth, the reflected laser light contains almost only the S-polarized component. On the other hand, since the surface of a foreign object generally has minute irregularities, when a foreign object is present within the irradiation spot, the irradiated S-polarized laser light is scattered and the polarization direction changes, and the reflected laser light has In addition to the S-polarized light component, a considerable amount of the P-polarized light component is included.

In response to this phenomenon, this wafer microscope inspection system detects foreign particles based on the level of the P-polarized component contained in the laser beam reflected from the wafer in the Z direction in the case of patterned wafers. Detects the presence and size of foreign objects.

On the other hand, in the case of a wafer with a blank film (including mirror-finished wafers), in order to increase detection sensitivity, the presence or absence and size of foreign particles can be determined based on the levels of the S-polarized reflected laser beam and the P-polarized reflected laser beam in the Z direction. Detect +M and see Figure 1! 16. The reflected laser light from the wafer is detected by a detection system 50 for detecting foreign matter according to the above principle;
The light enters an optical system common to a microscope 52 for visual observation of the wafer. That is, the reflected laser beam is transmitted through the objective lens 5.
4, via Half Mirror 56, BU IJ Sum 58 4.
The 5 degree prism 60 is reached.

In addition, a lamp 70 is provided for one-view observation.The visible light emitted from this lamp 70 allows the half mirror to be
56 and the objective lens 54, the wafer is illuminated.

The visible reflected light that has passed through the prism 60 and entered the microscope 2 side passes through the 60 degree prism 62 and the field lens 64.
, passes through the relay lens 66 in order and enters the eyepiece lens 68. Therefore, the eyepiece 68 allows the wafer 3
0 can be observed with a magnification 1 minute larger.

In this case, the range of the S-polarized laser beam spot on the wafer is located at the center of the field of view. The wafer 30 can also be observed at low magnification through the prism 58.

The reflected laser light that has entered the detection system side via the prism 60 passes through the aperture 4 provided in the slit 72 and is sent to the light receiving element 90.

Here, if the wafer 30 is a patterned wafer,
Since the S polarization cut filter 86 (polarizing plate) is moved to the position indicated by the wait 869, the P polarization of the reflected laser beam is
Only the polarized light component is extracted and enters the light receiving element 90. The wafer 30 is a wafer with a blank film (or a mirror wafer)
In this case, the S-polarized light cut filter 88 is moved to the position shown by the solid line, so the S-polarized light component of the reflected laser beam is also P-polarized.
The polarized light component also enters the light receiving element Y-90.

87 is a solenoid for moving the S polarization cut filter 86.

Figure 2 shows an enlarged view of the person's shell seen from the light-receiving surface side of the light-receiving element R90). In this figure, 90A is a light receiving section, and elongated light receiving apertures are arranged at regular intervals in the light receiving section 90A. A pin photodiode 90C as a photoelectric conversion element is provided inside each light receiving aperture 90B. Each pin photodiode 90
The light receiving area in the light receiving section 90A of C is substantially the same as the light receiving aperture 90B. As is clear from the figure, each light receiving area (indicated by 90B) is tilted at a predetermined angle with respect to the arrangement direction (vertical direction in the figure) of the pin photodiodes 90C, and has an elongated shape. When viewed from the direction perpendicular to the arrangement direction of 90C (horizontal direction in the figure), the adjacent light receiving area 90B
are virtually continuous.

Such a pin photodiode 90C and light receiving area 90
Except for the arrangement of B, this element is the same as the light receiving element r consisting of a conventional pin photodiode array.

Therefore, detailed description of the internal structure of the pin photodiode 90C will be omitted.

The field of view of each light-receiving area 90B of the light-receiving element J'90 and the aperture 4 of the slit 72 on the wafer will be explained with reference to FIG. In this figure, 74'
is the field of view of the aperture 4 on the wafer, and is included within the spot range of the S-modified laser beam. 90B° is the field of view of each light receiving area 90B. And field of view 90B
The arrangement direction of ゛ is a direction that is almost perpendicular to the scanning direction (described later), and when viewed from the scanning direction, the adjacent light receiving areas 90
B's field of view 90B' is substantially continuous. Therefore, as can be easily understood from FIG. 1, the light receiving element 90 is attached in such a direction that the arrangement direction of the pin photodiodes 90C is the Z direction. Now, reflected light from a region included in the field of view 90B'' of the wafer enters each light receiving area 90B, and is converted into an electric signal by each pin photodiode 90C.The electric signal (
In this embodiment, the detection signal (detection signal) is outputted from the end r provided in the light receiving element J'90 for each pin photodiode 90C. Then, as will be described later, the presence or absence of a foreign object in each light-receiving area field of view 90B' and the particle size of the foreign object are determined based on the level of the detection beam corresponding to each light-receiving area.

Here, the foreign matter inspection is performed while rotating the wafer and feeding it in the X direction (radial direction 11) as described above. According to such movement of the wafer 30, as shown in FIG.
A spot 30A of the S-polarized laser beam moves spirally on the upper surface of the wafer 30 from the outside toward the center. Detection system 50
and the microscope 52 is stationary, and the field of view 7 of the aperture 4 is
4' and the field of view 90B' of the light receiving area 90B are always included within the spot 30A and move to follow the spot 30A. That is, the wafer surface is inspected while being spiral scanned,
The scanning direction is approximately in the circumferential direction of the wafer 30.

Now, each detection signal output from the light-receiving element 90 includes, in addition to the signal component related to the foreign object, background noise determined by the condition of the spinal surface to be examined. In order to increase the signal-to-noise ratio of the signal and enable the detection of minute foreign objects, it is necessary to monitor the light receiving area 90B! 1IF90
There is a necessity to make B' smaller. However, in the case of a conventional wafer foreign matter inspection apparatus having one field of view, the pitch of the scanning lines (the locus of the field of view) must be made small, which increases the time required to scan and inspect the entire wafer surface.

On the other hand, in the case of the wafer foreign matter inspection device of the present invention,
A plurality of visual fields 90B' are arranged in a direction perpendicular to the scanning direction, and there is no gap between the visual fields 908' when viewed from the scanning direction. Therefore, each field of view 90B9 can be narrowed down sufficiently to increase the S/N of the detection signal, and at the same time, the scanning line pitch can be increased to shorten the inspection time.

Here, the case where u<1 angle of incidence φ will be explained. In conventional wafer foreign matter inspection equipment, when inspecting foreign matter on a wafer whose surface is coated with a blank film without a pattern such as a photoresist film or an aluminum vapor-deposited film, a light beam is applied to the wafer at a fairly large irradiation angle, for example, 30 degrees. It is designed to illuminate the surface.

According to the inventor's research, the background noise of the detection signal in such conventional equipment includes the wafer surface (
In addition to the noise component determined by the state of the blank film (surface), it also includes noise components related to the internal state of the blank film and noise components related to the state of the wafer base surface of the blank film. Due to the principle of using reflected light from the wafer surface, it is impossible to completely remove the initial noise component, and its influence is not fatal. However, the latter two noise components are affected by the internal state of the wafer and directly cause false detection, so they should be removed.

According to the inventor's research, in conventional equipment, because the beam irradiation angle is large, a portion of the light beam incident on the wafer surface enters the interior of the blank film, is reflected on the wafer base surface, and causes the blank film to be exposed again. It was found that the above-mentioned undesirable noise component was generated due to the fact that the light passes through the wafer surface and enters the photoelectric element.

Therefore, in this embodiment, the irradiation angle of the light beam is selected to be small by I· as described above so that the light beam is substantially totally reflected on the wafer surface, thereby preventing the light beam from penetrating into the inside of the wafer. -I'm looking forward to it.

Referring again to FIG. A capacitance displacement meter 53 is provided near the objective lens 54 and facing the wafer surface. This capacitance displacement meter 53 is a means for detecting the distance between the wafer surface and the objective lens of the optical system, and outputs a signal proportional to the displacement from the reference distance according to the capacitance of fffl with the wafer surface. do.

If the distance is the reference distance, that is, if the displacement electric current from the reference position is zero, the focus of the objective lens 54 is on the wafer surface.

Next, the signal processing and control system of this wafer foreign matter inspection apparatus will be explained with reference to FIG.

Each detection signal output from the light receiving element 90 is amplified by an amplifier 100 and then input to each level comparison circuit 102 .

Here, there is a relationship as shown in FIG. 6 between the particle size of the foreign matter of the sea urchin pigeon and the level of the detection signal. In this figure, Ll, L2. L3 is a threshold value of each level comparison circuit 102.

Each level comparison circuit 102 compares the level of each input signal with each threshold value, and outputs a binary code indicating the result of comparison with each threshold value. For example, if the detection signal level is less than the threshold value L/, it outputs (000) 2, and if the detection signal level is more than the threshold value 2 and less than the threshold value 3, it outputs (011) 2, and the detection signal level or the threshold value is If t, a - L then (111
)2 is output.

The output code of each level comparison circuit 102 is input to an interface circuit 108 that interfaces with the data processing system 104.

The output signal of the capacitive displacement meter 53 is input to an analog/digital converter 103, converted into a binary code (distance code), and inputted to an interface circuit 108.

Further, the interface circuit 108 receives a signal (binary code) indicating information about the rotation angle position 0 and the X direction (radial direction) position X at each time point from the rotary encoder and the linear encoder.
It is manually operated via 112.

Each human code to the interface circuit 108 is
The data is taken into a certain register inside the interface circuit 108 at a constant cycle and temporarily held there.

Further, inside the interface circuit 108, the stepping motors 14, 1 are connected to the data processing system 104.
9. There is also a register in which control information for the DC motor 24 and solenoid 87 is set. According to the control information set in this register, the motor controller tte controls the stepping motors 14, 19.24, and the solenoid driver 117 controls the solenoid 8.
7 drive control is performed.

The data processing system 104 includes a microprocessor, a memory for storing programs, data, etc., a floppy disk device for storing test results, etc., a keyboard and CRT display device for interacting with the operator, and a foreign matter map of the wafer. It consists of an X-Y plotter and the like for printing out.

Next, automatic inspection operation for foreign substances will be explained.

When the wafer 30 is set at a predetermined position on the rotation stage 22, the data processing system 104 generates motor control information for positioning the X stage 10, the Z stage 20, and the rotation stage 22 at the initial positions according to the inspection processing program, and If the wafer 30 is a patterned wafer, move the S-polarized light cut filter 86 to the position indicated by the symbol 86, and if the wafer 30 is a wafer with a blank film (or mirror wafer), move the S-polarized light cut filter 86 to the solid line position. Solenoid control information for movement is set in the internal register of the interface circuit 108. According to this motor control information, the motor controller 11
6 controls the stepping motors 14 and 19 and the DC motor 24 to move each stage to its initial position. Similarly,
Solenoid driver 117 energizes or deenergizes solenoid 87 according to solenoid control information.

The data processing system 104 then starts the DC motor 24 via the interface circuit 108.
The distance code is read from the internal register of the 08 four times (generally multiple times) at fixed time intervals, and sequentially written into the internal memory.

In this way, distance codes for four locations (generally, multiple locations) near the outer periphery of the wafer 30 are obtained in the internal memory. Note that the reading time interval of the distance code is selected so that the distance detection points are approximately evenly distributed in the circumferential direction of the wafer 30.

The data processing system 104 calculates the average value of the four read distance codes (displacement from the reference distance position).The data processing system 104 moves the Z stage 20 in a distance and direction that cancels out the average displacement. control information is provided to the motor controller 116 via the interface circuit 108. The objective lens 54 is now focused on almost the entire area of the wafer, and the actual foreign matter inspection process begins.

First, the data processing system 104 instructs the motor controller 116 to start scanning through the interface circuit 108. Upon receiving this instruction, the motor controller 116 drives the stepping motor 14 and the DC motor 24 so as to perform the above-described helical scanning at a constant speed.

Data processing system 104 includes interface circuit 1
The contents of a specific internal register of 08, that is, the code of the level comparison result of each detection signal and the code of scanning position X, 0 are sequentially taken in and written into the internal memory. A zero test is performed for each code in the level comparison result. If the code of a certain detection signal 45 is zero, it is determined that there is no foreign object in the field of view 90B' corresponding to that detection signal shift. If the code of a certain detection signal is not zero, it is tentatively determined that a foreign object exists in the field of view 908' corresponding to that detection signal.

If even one non-zero level comparison result code is detected, the position of the field of view 90B' corresponding to that code is calculated from the scanning position information at that time.

In other words, the position in the θ direction is determined by the position indicated by the output code of the rotary encoder, but the position in the X direction is determined by the position indicated by the output code of the linear encoder and the corresponding arrangement position of the field of view 90B. Find by adding or subtracting.

In this way, the correction process for the foreign object position becomes extremely simple compared to the case where the conventional light receiving elements are arranged diagonally or when two light receiving elements are used side by side. In addition, mounting eliminates the trouble of adjusting the position and the problem of positional error, which is the case when two conventional light-receiving elements are arranged side by side.

Now, the data processing system 104 compares the position (foreign object position) obtained as described above with the positions of other foreign objects that have already been detected and stored in the internal memory.

If this comparison is negative, it is determined that a new foreign object has been detected, and the information on the position of the foreign object and the level comparison result code (foreign object particle size information +V) are stored in the internal memory. If the comparison results in a match, it is determined that the - section of the already detected foreign object has been detected 71 times, and information on the currently detected foreign object is not stored in the internal memory.

In parallel with this, the data processing system 104 checks whether the scanning has progressed to the scanning end position based on the scanning position information taken in from the interface circuit 108. When determining that scanning has ended, data processing system 104 sends a scanning stop instruction to motor controller 116 through interface circuit 108. In response to this instruction, the motor controller 116 stops driving the stepping motor 14 and the DC motor 24 by +1.

Next, the data processing system 104 transfers the foreign matter information stored in the internal memory to the floppy disk device for storage, and completes the automatic foreign matter inspection for one wafer.

There are various processing modes such as printing out a map of detected foreign objects, visually observing foreign objects detected by automatic inspection, and merging the observation results with foreign object information. Since it is not directly related to the gist, its explanation will be omitted.

Further, the automatic foreign matter processing is executed according to a program, and a person skilled in the art can easily understand such a program as follows.
Since it can be easily realized based on the explanation of -, detailed explanation thereof will be omitted.

Here, the present invention is not limited to the above-mentioned embodiments, but can be implemented with appropriate modifications.

For example, the photoelectric conversion element of the light receiving element is a suitable photoelectric conversion element other than a pin photodiode, such as a MOS.
It may also be a type photoelectric conversion element. Further, instead of outputting the signals of each photoelectric conversion element independently in parallel, for example, a shift register (CCr) or the like may be provided to output the signals of each photoelectric conversion element in series. In this way, the levels of the detection signals can be compared using one common circuit.

In the relationship between the light receiving element r and the laser irradiation direction, the laser irradiation direction may be from the X direction.

The distance detection stage for focus adjustment is not limited to a capacitive displacement meter, but may be replaced by other means capable of detecting distance with high precision.

In the above embodiment, focus adjustment is performed by moving the rotary stage integrally with the two stages, but the focus adjustment is performed by moving the rotary stage integrally with the two stages.
and may be modified to move the rotation stage,
This can be done by changing the relative distance between the wafer and the optical system (objective lens 54).

The distance detection location is not limited to the vicinity of the outer periphery of the wafer.

It is not necessary that the scanning position of the detection system always be within the visual life of the microscope, and it is sufficient that the scanning position and the field of view can maintain a constant positional relationship.

However, if the above embodiment is used, processing such as identifying a person during visual observation is easy.

Scanning for inspection is not limited to spiral scanning, but may also be linear scanning, for example. However, since linear scanning stops at the scanning edge, the scanning time tends to increase, and when scanning a circular valley surface such as a wafer, position control at the scanning edge tends to become complicated. There is. Therefore, when inspecting foreign objects such as wafers, helical scanning is generally advantageous.

Further, the present invention is also applicable to similar wafer foreign matter inspection apparatuses that utilize light beams other than polarized laser light.

Furthermore, the present invention is generally applicable to apparatuses for inspecting foreign matter on the surface of objects to be inspected other than wafers.

[Effects of the Invention] As detailed above, according to the present invention, the light receiving area of each photoelectric conversion element of the light receiving element for receiving reflected light from the surface to be inspected and converting it into an electric signal is The photoelectric conversion elements are arranged at an array pitch such that the adjacent light-receiving areas are substantially continuous when viewed from a direction perpendicular to the array direction, and each light-receiving area is inspected. The field of view on the surface is moved in a specific direction, and the direction of the array is selected in a direction approximately perpendicular to the scanning direction of the field of view of the light receiving area, so that there is no gap in the direction perpendicular to the running direction. The inspection time can be shortened by observing the valley surface to be inspected all at once using multiple fields of view lined up.
By dividing the field of view of each light-receiving area by 1.0 mm, the S/N of the foreign object detection signal can be increased by 1-1, allowing highly accurate foreign object detection. It is possible to achieve the effect that problems such as those caused by arranging them at an angle with respect to each other or arranging a plurality of them in a staggered manner do not occur.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing the optical system etc. of the wafer foreign matter inspection device according to the present invention, FIG. 2 is a schematic enlarged plan view of a light receiving element, and FIG. 3 is a signal processing and control system of the wafer foreign matter inspection device. Schematic block diagram, Figure 4 is an explanatory diagram of each light receiving area of the light receiving element and the field of view of the slit aperture on the wafer, Figure 5 is an explanatory diagram of wafer scanning, and Figure 6 is the particle size of foreign particles and detection signal level. 3 is a graph showing the relationship with the threshold value for level comparison. 10... X stage, 14. 19... Stamping motor, 22... Rotating stage, 24... DC motor, 30... Wafer, 36. 38... S polarization laser oscillator, 50... ...Detection system, 52...Microscope, 72.
...Slit, 86...S polarization cut filter, 87
...Solenoid, 90...Photodetector f', 90A...
・Light-receiving surface, 90B...Light-receiving aperture (light-receiving area)
, 90C... Bin photodiode, 90B'... Field of view of light receiving area, 100... Amplifier, 102... Level comparison circuit, 104... Data processing system, 10
8... Interface circuit, 11 B-... Motor controller, 117... Solenoid driver.

Claims (2)

[Claims] (1) A light beam is irradiated onto the surface to be inspected, the reflected light from the surface to be inspected is received by a light receiving element and converted into an electrical signal, and based on the electrical signal, the presence or absence of foreign matter on the surface to be inspected is determined. In the foreign matter inspection device, the light receiving element is formed by a plurality of photoelectric conversion elements arranged linearly, and the light receiving area on the light receiving surface of each of the photoelectric conversion elements is inclined with respect to the direction of the arrangement, and The photoelectric conversion elements are arranged at an arrangement pitch such that the adjacent light-receiving areas are substantially continuous when viewed from a direction perpendicular to and the direction of the arrangement is a direction in which the field of view of the light receiving area on the surface to be inspected is aligned in a direction substantially perpendicular to the specific direction. (2) The foreign matter inspection apparatus according to claim 2, wherein the field of view of each of the light receiving areas on the surface to be inspected is moved spirally on the surface to be inspected.