JPH06249791A - Flaw inspection apparatus - Google Patents

Abstract

PURPOSE:To properly detect a flaw irrespective of the properties on the surface of a wafer. CONSTITUTION:A flaw inspection apparatus is provided with a holding stage device 11 for a wafer 1, with an inspection-light irradiation device 20 by which the wafer is irradiated with inspection light 21, with a scattered-light detector 34 which detects scattered light 31 from the inspection light in the wafer and with a flaw judgment device 40 which judges a flaw on the basis of its inspection result. In the flaw inspection apparatus, an offset processing circuit 39 which lowers an offset value so as to correspond to the reflection factor, the absorption factor and the like of the wafer 1 is interposed and installed in a signal processing circuit for the scattered-light detector 34. The offset value of a DC component is reduced by the offset processing circuit 38, and a scattered-light signal waveform in which the offset value of the output signal waveform of the scattered-light detector 34 is high, in which its scattered-light signal wavefom is saturated by the dynamic range of the detector 34 and which corresponds to a flaw signal buried in its component becomes tangible. As a result, the flaw can be deteted irrespective of the properties on the surface of the wafer 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a defect inspection apparatus, and more particularly,
The present invention relates to a technique for detecting minute foreign matter on a wafer surface such as a semiconductor LSI wafer or a glass mask with high sensitivity, and for example, to a technique effectively used in a method for manufacturing a semiconductor integrated circuit device.

In this document, the term "wafer" is intended to broadly include semiconductor wafers, masks, reticles, and other plate-like materials for manufacturing integrated circuits, in principle.

The term "defect" simply includes, as a general rule, both foreign particles and defects in the pattern itself caused by foreign particles.

Furthermore, when simply referring to "integrated circuit device", in principle, a semiconductor integrated circuit (monolithic I
C) broadly includes a single transistor formed on a semiconductor wafer and an integrated circuit formed on an insulating plate such as sapphire or garnet.

[0005]

2. Description of the Related Art Generally, in a manufacturing process of a semiconductor integrated circuit device, a large number of photomasks are used and patterns are sequentially formed on a wafer by a photolithography technique. However, pinholes, disconnections, etc. occur in the electrodes, protective film, etc. due to defects due to foreign substances during pattern formation and defects due to foreign substances mixed in during the photo process. The problem of occurrence of pattern defects such as short circuit between electrodes becomes a problem with smaller foreign matters as semiconductor integrated circuits are highly integrated and wiring patterns are miniaturized.

Nowadays, as the degree of integration of semiconductor devices becomes higher and the pattern becomes finer, the line width of a circuit pattern is about 1 μm or less. In order to manufacture such a semiconductor device with a high yield, it is necessary to inspect foreign substances adhering to the surface of the wafer as a wafer, quantitatively grasp the cleanliness of various process apparatuses, and appropriately manage the process. In order to accurately manage the process as described above, in the manufacturing process of an integrated circuit device, an automatic defect inspection has been conventionally performed on a wafer by a defect inspection device.

The conventional defect inspection apparatus is roughly classified into two categories. The first is an image comparison type defect inspection apparatus that compares a standard pattern stored in advance. This type of defect inspection apparatus has high accuracy but low throughput and is expensive. The second is a defect inspection apparatus that uses inspection light. This type of defect inspection system
The accuracy is medium, but the throughput is high and the price is medium.

As a defect inspection apparatus using inspection light, an inspection light irradiation device for irradiating a wafer with the inspection light and a scattered light detector for detecting scattered light of the inspection light on the wafer are provided. In some cases, the presence / absence, size, etc. of a foreign substance are detected based on the detection result of the scattered light detector.

In the defect inspection apparatus in which the scattered light detector is used, a signal processing system including an amplifier, an A / D converter, a microprocessor unit, etc., as a signal processing system in the scattered light detector. A circuit is used, and only a foreign substance is detected by setting a threshold value in the signal processing circuit for the detection signal from the scattered light detector.

As an example of describing a conventional defect inspection apparatus for patterned wafers, Japanese Patent Laid-Open Publication Nos. 54-101390, 59-186324, 59-65428, and 55-55 are disclosed. 124008 and Japanese Patent Application No. 62-311904.

As an example in which a similar technique is described, Japanese Patent Application Laid-Open Publication No. 62-223649,
JP-A-62-223650, JP-A-62-22365
1, JP-A-63-82348, JP-A-64-354.
No. 5, Japanese Patent Application No. Sho 63-41999, etc.
There is.

Further, as an example in which a technique using similar polarized light is described, Japanese Patent Application No. 62-272958 is cited.
, Japanese Patent Application No. 62-279238, Japanese Patent Application No. 63-3.
23276 and so on.

Further, as an example in which a method for adjusting the light quantity is described, Japanese Patent Application Laid-Open Publication No. 60-18895.
No. 0 and No. 62-106324.

[0014]

By the way, in the development of a semiconductor integrated circuit device, in order to verify whether or not the developed product can be manufactured by an existing thin film forming apparatus, a so-called dummy wafer is manufactured before actual production is started. It is conceivable to carry out an experiment for forming a thin film by the existing thin film forming apparatus. Then, in order to make a diagnosis or evaluation of this experiment, it is necessary to perform a foreign matter inspection for a foreign matter attached to the thin film formed on the dummy wafer.

However, in the conventional defect inspection apparatus using the inspection light, the scattered light detector has a difference in the type and film thickness of the thin film (hereinafter sometimes referred to as film formation) formed on the dummy wafer. According to the present inventor, there is a problem in that the offset value becomes high, and the foreign matter adhered to the surface of the film is saturated in the offset value and the dynamic range of the amplifier, so that the foreign matter cannot be detected. Was revealed.

An object of the present invention is to provide a defect inspection technique capable of always maintaining a constant defect detection sensitivity regardless of the surface properties of the inspection object.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0018]

The typical ones of the inventions disclosed in the present application will be outlined below.

That is, a stage device for holding the inspection object, an inspection light irradiation device for irradiating the inspection object with the inspection light, and a scattered light detector for detecting scattered light of the inspection light on the inspection object. In the defect inspection apparatus comprising a defect determination device for determining a defect based on the detection result of the scattered light detector, an offset processing circuit is provided in the signal processing circuit of the scattered light detector, The offset processing circuit is configured to reduce the entire offset value of the detection signal due to the difference in reflectance or absorption rate of the object to be inspected and prevent the scattered light detection signal from being saturated in the dynamic range of the amplifier. Is characterized by.

Further, a stage device for holding the inspection object, an inspection light irradiation device for irradiating the inspection object with the inspection light, and a scattered light detector for detecting scattered light of the inspection light on the inspection object. And a defect inspection device comprising a defect determination device for determining a defect based on the detection result of the scattered light detector, wherein an optical filter having different transmittance between the scattered light detector and the inspection object. Are interchangeably provided, and these optical filters are configured to be exchanged according to differences in reflectance, absorptance, etc. of the surface of the object to be inspected.

Further, a stage device for holding the inspection object, an inspection light irradiation device for irradiating the inspection object with the inspection light, and a scattered light detector for detecting scattered light of the inspection light on the inspection object. And a defect determination device that determines a defect based on the detection result of the scattered light detector, in an optical filter having different transmittance between the inspection light irradiation device and the inspection object. Are interchangeably provided, and these optical filters are configured to be exchanged according to differences in reflectance, absorptance, etc. of the surface of the object to be inspected.

[0022]

According to the above-mentioned first means, the output signal waveform of the scattered light detector is reduced by reducing the offset value of the DC component by the offset processing circuit provided in the signal processing system of the scattered light detector. Has a high offset value, and its output signal waveform is saturated in the dynamic range of the amplifier, so that the scattered light signal waveform corresponding to the defect signal buried in the component can be revealed, so that the object to be inspected Defects can be detected regardless of the surface properties.

According to the above-mentioned second means, an optical filter having a predetermined transmittance corresponding to the reflectance or absorptance of the surface of the inspection object is provided between the scattered light detector and the inspection object. By interposing it, the detection signal level of the scattered light detector itself can be lowered, so the offset value of the output signal waveform of the scattered light detector is high and the output signal waveform is saturated in the dynamic range of the amplifier. As a result, the scattered light signal waveform corresponding to the defect signal buried in the component can be revealed, and as a result, the defect can be detected regardless of the property of the surface of the inspection object.

According to the above-mentioned third means, an optical filter having a predetermined transmittance corresponding to the reflectance or absorptance of the surface of the inspection object is provided between the inspection light irradiator and the inspection object. Since the intensity of the inspection light itself can be reduced by the interposition, the offset value of the output signal waveform of the scattered light detector is high, and the output signal waveform is saturated in the dynamic range of the amplifier and its component The scattered light signal waveform corresponding to the defect signal buried therein can be revealed, and as a result, the defect can be detected regardless of the property of the surface of the inspection object.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing a foreign matter inspection apparatus for a wafer which is an embodiment of the present invention. 2 (a),
(B), (c) is each diagram for explaining the action.

In the present embodiment, the defect inspection apparatus according to the present invention is configured as a wafer foreign matter inspection apparatus 10 for inspecting the foreign matter 2 on the wafer 1. The wafer foreign matter inspection apparatus 10 includes a stage device 11. The stage device 11 includes an X stage and a Y stage for scanning a wafer 1 as an inspection object, and a θ stage (not shown) for rotating in a θ direction. No.), an automatic focusing mechanism (not shown), and a controller 12 for controlling them. Then, in order to inspect the entire surface of the wafer 1, the stage device 11 executes X and Y scanning of the wafer 1. During this scanning, the coordinate position information about the wafer 1 as the inspection object is sequentially input from the controller 12 to the foreign matter determination device described later.

An inspection light irradiation device 20 is installed above the stage device 11. The inspection light irradiation device 20 includes a laser light irradiation device 22 that irradiates the wafer 1 with a laser light 21 as inspection light, a condenser lens 23 that condenses the laser light 21, and a galvanometer mirror 24. The emitted laser light 21 is applied to the wafer 1 as the inspection object held on the stage device 11.

In the present embodiment, the inspection light irradiating device 20 comprises an epi-illumination system 25 for irradiating the wafer 1 with the laser light 21 vertically and an oblique illumination system 26 for irradiating the laser light 21 on the wafer 1 obliquely. A system is provided, and an appropriate illumination system of two systems is used depending on the condition of the surface of the wafer 1.

When the height of the surface of the wafer 1 changes when the laser beam 21 is irradiated on the wafer 1, the irradiation position of the laser beam 21 changes and the foreign matter detection performance deteriorates. A matching mechanism (provided in the stage device 11) is required. An automatic focusing mechanism of this type is disclosed in, for example, Japanese Patent Laid-Open No. 58-70.
Although a projection fringe pattern contrast detection method such as that disclosed in Japanese Patent No. 540 can be used, the description will be made accordingly.

A scattered light detection device 30 is installed diagonally above the stage device 11. This scattered light detection device 30
Is an objective lens 32 that collects the scattered light 31 diffusely reflected on the surface of the wafer 1 as the surface of the wafer 1 is irradiated, and a scattered light detector that collects the scattered light 31 collected by the objective lens 32. Relay lens 3 for focusing on the light receiving surface of 34
3 and a scattered light detector 34 for detecting the scattered light 31. As the scattered light detector, for example, a Photomar or a two-dimensional solid-state image pickup photoelectric conversion element can be used.

An amplifier 35 is connected to the scattered light detector 34, and an A / D converter 36 is connected to the amplifier 35. A monitor 37 is connected between the scattered light detector 34 and the amplifier 35, and the monitor 37 is configured to monitor the output signal waveform of the scattered light detector 34.

In the present embodiment, an offset processing circuit 38 is disposed between the scattered light detector 34 and the amplifier 35, electrically behind the monitor 37, and the offset processing circuit 38 is an operating device. The offset value of the DC component can be reduced by 39. That is, the operator operates the operating device 39 while monitoring the output signal waveform of the monitor 37 to reduce the offset value of the DC component in the output signal of the scattered light detector 34, thereby adjusting the dynamic range of the amplifier 35. The foreign signal that is saturated and buried in the component can be revealed.

A foreign matter determination device 40 is connected to the output terminal of the A / D converter 36 in the scattered light detection device 30,
The foreign matter determination device 40 determines presence / absence and size of foreign matter on the wafer 1 based on the transmission data from the A / D converter 36, and the determined data and the coordinate position from the controller 12 of the stage device 11. The coordinate position of the foreign matter is specified by collating with the data.

Next, a brief description will be given of a method for inspecting foreign matter on a wafer, which is used by the apparatus for inspecting foreign matter on wafer 10 having the above-mentioned structure.

When the wafer 1 is set on the stage device 11, the inspection light irradiation device 20 irradiates the wafer 1 with laser light 21 as inspection light. This laser light 2
1, the scattered light 31 is generated from the foreign matter 2 as a defect on the wafer 1 and the circuit pattern (not shown),
The scattered light 31 is condensed by the objective lens 32 and is imaged on the scattered light detector 34 through the relay lens 33.

At this time, scattered light 31 from the circuit pattern
Has a regularity, the scattered light 31 from the circuit pattern is shielded by a light shielding element (not shown) formed of a spatial filter or an analyzer provided on the Fourier transform surface of the pattern surface of the wafer 1. . On the other hand, foreign matter 2
Since the scattered light 31 from is irregular, it passes through the spatial filter or the analyzer and is imaged on the scattered light detector 34. Therefore, only the foreign matter 2 can be detected.

The detection signal of the scattered light 31 from the foreign matter 2 detected by the scattered light detector 34 is amplified by the amplifier 35 and is also A / D converted by the A / D converter 36.
It is converted and input to the foreign matter determination device 40.

The foreign matter determination device 40 determines the presence or absence of the foreign matter 2 and the size thereof based on the detection signal, and compares this determination data with the coordinate position data from the controller 12 of the stage device 11. Thus, the coordinate position of the foreign material 2 is specified.

The data relating to the foreign matter 2 thus determined and whose coordinate position is specified is, for example,
The foreign matter determination device 40 outputs the timely information to a host computer (not shown), a display device (not shown), or the like, which executes production control in an integrated manner.

By the way, for example, in the development of a semiconductor integrated circuit device, when a foreign substance is inspected for a foreign substance attached to a thin film formed on a dummy wafer, scattering occurs due to the difference in the type and thickness of the thin film formed on the dummy wafer. The offset value in the photodetector 34 becomes high, and the foreign matter 2 adhering to the surface of the film formation becomes saturated in the offset value and the dynamic range of the amplifier 35, so that the foreign matter 2 cannot be detected. It was revealed by the present inventors that there is.

For example, when the reflectance of the thin film formed on the dummy wafer to be inspected is high, the epi-illumination system 25 is used as the inspection light irradiation device 20, and the output signal of the scattered light detector 34 at that time is used. The waveform 50 becomes the state shown in FIG.

That is, the offset value 52 of the output signal waveform 50 is slightly higher. Further, the scattered light signal waveform 51 indicating the foreign matter 2 in the output signal waveform 50 is saturated with respect to the upper limit level 53 of the dynamic range in the amplifier 35. Therefore, the scattered light signal waveform 51 is crushed by the upper limit level 53.

Since the size of the foreign matter 2 is proportional to the size of the scattered light signal waveform 51, when the scattered light signal waveform 51 is in a crushed state, the size of the true scattered light signal waveform 51 is known. do not do. That is, the size of the foreign matter 2 detected by the scattered light signal waveform 51 cannot be specified.

Here, when the size of the scattered light signal waveform 51 is binarized, the scattered light signal waveform 51 is partitioned by the threshold value 54 in order to obtain the size of the foreign matter 2. When the threshold value 54 is selected, if the scattered light signal waveform 51 is in a crushed state, the threshold value 54 cannot be properly selected. Further, when the threshold value 54 is selected to be high because the offset value 52 is high, the size of the foreign matter 2 cannot be accurately determined.
For example, a small foreign matter is erroneously determined as a large foreign matter.

If the thin film formed on the dummy wafer to be inspected has a large grain size (size of the unevenness of the surface to be irradiated with laser light), the oblique illumination system 25 is used as the inspection light irradiation device 20. Then, the output signal waveform 60 of the scattered light detector 34 at that time becomes the state shown in FIG.

That is, the offset value 62 of the output signal waveform 60 becomes very high. Further, the scattered light signal waveform 61 in the output signal waveform 60 indicating the foreign matter is saturated with respect to the upper limit level 63 of the dynamic range in the amplifier 35. Therefore, the scattered light signal waveform 61 is crushed by the upper limit level 63.

Since the size of the foreign matter 2 is proportional to the size of the scattered light signal waveform 61, when the scattered light signal waveform 61 is in a crushed state, the true size of the scattered light signal waveform 61 is known. do not do. That is, the size of the foreign matter 2 detected by the scattered light signal waveform 61 cannot be specified.

Here, when the size of the scattered light signal waveform 61 is binarized, the scattered light signal waveform 61 is partitioned by the threshold value 64 in order to obtain the size of the foreign matter 2. When the threshold value 64 is selected, the threshold value 64 cannot be appropriately selected because the offset value 62 is extremely high. Therefore, the size of the foreign material 2 cannot be specified.

In this embodiment, when the output signal waveform of the scattered light detector 34 is in the state shown in FIGS. 2 (a) and 2 (b), the offset processing circuit 38 cuts the DC component. , For example, the state shown in FIG. 2C is controlled. That is, when the output signal waveform of the monitor 37 is in the state shown in FIG. 2A or 2B, the operator operates the operation device 39 while monitoring the monitor 37 to generate scattered light. By reducing the offset value of the DC component in the output signal of the detector 34, the output signal waveform monitored by the monitor 37 is shown in FIG.
Control is performed so that the state shown in FIG.

Output signal waveform 7 shown in FIG. 2 (c)
When 0, the offset value 72 becomes low. Further, a scattered light signal waveform 71 indicating a foreign matter in the output signal waveform 70
Is completely distant from the upper limit level 73 of the dynamic range in the amplifier 35 and becomes completely unsaturated.
Therefore, the scattered light signal waveform 71 that is saturated in the dynamic range of the amplifier 35 and is buried in the component thereof is properly manifested. .

The output signal waveform 70 has a low offset value 72, and the scattered light signal waveform 71 indicating foreign matter in the output signal waveform 70 is far away from the upper limit level 73 of the dynamic range in the amplifier 35. Therefore, for example, the threshold of 7
4, 75 and 76 can be selected with appropriate difference values. Then, the large, medium and small thresholds 74, 75,
The large, medium and small foreign matters are properly identified by 76.

According to the above described embodiment, the following effects can be obtained. (1) The offset value of the DC component is reduced by the offset processing circuit provided in the signal processing system of the scattered light detector, so that the offset value of the output signal waveform of the scattered light detector is high and its output Since the signal waveform is saturated in the dynamic range of the amplifier and the scattered light signal waveform corresponding to the foreign matter signal buried in the component can be revealed, foreign matter can be detected regardless of the surface properties of the inspected object. can do.

(2) According to the above (1), the detection sensitivity of the scattered light detector can always be kept constant, so that the inspection accuracy of the defect inspection apparatus can always be kept constant. Quality and reliability can be improved.

(3) The capabilities of the inspection light irradiation device 20 and the scattered light detector 34 are controlled by automatically controlling the output signal waveform of the scattered light detector 34 so that it is always constant with respect to the ground level. Even if it is not changed, the detection sensitivity of the foreign matter inspection device 10 can be always maintained constant.

FIG. 3 is a block diagram showing a foreign matter inspection apparatus for a wafer which is Embodiment 2 of the present invention. FIG. 4 (a),
(B) is each diagram for explaining the action.

Wafer particle inspection apparatus 1 according to the second embodiment
0A is different from the wafer foreign matter inspection apparatus 10 according to the first embodiment in that an optical filter 41 is provided in the scattered light detection apparatus 30 instead of the offset processing circuit 38. That is, an ND (Neutra), which is an example of an optical filter, is provided in an optical front position of the scattered light detector 34.
l Density) filter 41 is arranged so as to be exchangeable.

Next, the operation of the wafer particle inspection apparatus 10A according to the second embodiment will be described with reference to FIG.

In FIG. 4 (a), a wafer foreign matter inspection device without an ND filter 41 is used, and an oblique illumination system is used as an inspection light irradiation device.
7 shows an output signal waveform of a scattered light detector when a foreign matter inspection is performed on a dummy wafer on which an aluminum film is formed.

That is, the output signal waveform 80 of the scattered light detector shown in FIG.
2 is very high. Further, the scattered light signal waveform 81 indicating the foreign matter in the output signal waveform 80 is saturated with respect to the upper limit level 83 of the dynamic range in the amplifier. Therefore, the scattered light signal waveform 81 is crushed by the upper limit level 83.

Since the size of the foreign matter 2 is proportional to the size of the scattered light signal waveform 81, the true size of the scattered light signal waveform 81 is found when the scattered light signal waveform 81 is crushed. do not do. That is, the size of the foreign matter 2 detected by the scattered light signal waveform 81 cannot be specified.

Here, when the size of the scattered light signal waveform 81 is binarized, the scattered light signal waveform 81 is divided by the threshold value 84 in order to obtain the size of the foreign matter 2. When the threshold value 84 is selected, the threshold value 84 cannot be properly selected because the offset value 82 is extremely high. Therefore, the size of the foreign material 2 cannot be specified.

In this embodiment, when the output signal waveform of the scattered light detector 34 is in the state shown in FIG. 4 (a), the reflectance and absorption of the surface of the aluminum coating applied to the dummy wafer are obtained. N having a predetermined transmittance corresponding to the transmittance
The D filter 41 is provided between the scattered light detector 34 and the wafer 1. When the ND filter 41 is provided between the scattered light detector 34 and the wafer 1, the DC component is cut by the ND filter 41, and the state is controlled to the state shown in FIG. 4B.

That is, when the output signal waveform of the monitor 37 is in the state shown in FIG. 4A, the operator appropriately replaces the ND filter 41 while monitoring the monitor 37, and scatters. By appropriately reducing the offset value of the DC component in the output signal of the photodetector 34,
The output signal waveform monitored by the monitor 37 is shown in FIG.
Control is performed so that the state shown in FIG.

Output signal waveform 9 shown in FIG. 4 (b)
When 0, the offset value 92 becomes low. Further, a scattered light signal waveform 91 indicating the foreign matter 2 in the output signal waveform 90
Is completely unsaturated with respect to the upper limit level 93 of the dynamic range in the amplifier 35 and becomes completely unsaturated.
Therefore, the scattered light signal waveform 91 saturated in the dynamic range of the amplifier 35 and buried in the component is properly manifested. .

The output signal waveform 90 has a low offset value 92, and the scattered light signal waveform 91 indicating the foreign matter 2 in the output signal waveform 90 is far from the upper limit level 93 of the dynamic range in the amplifier 35. Since it is in a state, for example, the threshold value of 9
4, 95 and 96 can be selected with appropriate difference values. Then, the large, medium and small thresholds 94, 95,
By 96, the large, medium, and small foreign matters are properly identified.

According to the second embodiment described above, the same effect as that of the first embodiment can be obtained. That is, the offset value of the output signal waveform of the scattered light detector is high by reducing the offset value of the DC component by the ND filter provided between the scattered light detector and the wafer, and
Since the output signal waveform is saturated in the dynamic range of the amplifier and the scattered light signal waveform corresponding to the foreign matter signal buried in the component can be revealed, the foreign matter is irrespective of the surface property of the object to be inspected. Can be detected.

FIG. 5 is a block diagram showing a foreign matter inspection apparatus for wafers, which is Embodiment 3 of the present invention.

Wafer particle inspection apparatus 1 according to the third embodiment
0B differs from the wafer foreign matter inspection apparatus 10 according to the first embodiment in that the inspection light irradiation apparatus 20 is provided with an optical filter 42 instead of the offset processing circuit 38. That is, an ND (Neutr), which is an example of an optical filter, is provided at an optical rear position of the inspection light irradiation device 20.
The al Density) filter 42 is arranged so as to be replaceable.

According to the third embodiment, the same effect as that of the first embodiment can be obtained. That is, since the intensity of the inspection light is weakened by the ND filter 42 provided between the inspection light irradiating device 20 and the wafer 1, the offset value of the DC component is relatively reduced, so that the scattering occurs. The offset value of the output signal waveform of the photodetector is high, and the output signal waveform is saturated in the dynamic range of the amplifier and the scattered light signal waveform corresponding to the foreign matter signal buried in the component can be revealed. As a result, the foreign matter can be detected regardless of the surface property of the inspection object.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, although omitted in the above embodiment for convenience of explanation, the signal processing system of the scattered light detection apparatus has a scattered light signal waveform and a haze signal (corresponding to the surface of the wafer to be inspected) corresponding to the foreign matter signal. An electrical filter may be provided to separate the signal corresponding to the swell).

Further, the optical filters provided in the scattered light detecting device and the inspection light irradiating device are not limited to the ND filters, but other optical filters can be used.

In the above description, the case where the invention made by the present inventor is mainly applied to the foreign matter inspection technology for dummy wafers, which is the field of application of the background, has been described, but the present invention is not limited thereto and is actually manufactured. Not only the foreign matter inspection technology for the mirror-finished wafer and the wafer on which the pattern is formed, but also the defect inspection technology for those wafers other than the foreign matter inspection, and the defects in the plate-like objects such as the photomask, liquid crystal panel, and printed wiring board It can be applied to all inspection techniques.

[0074]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.

By providing an offset processing circuit in the signal processing system of the scattered light detector and reducing the offset value of the DC component by this offset processing circuit, the offset value of the output signal waveform of the scattered light detector is high, In addition, since the output signal waveform is saturated in the dynamic range of the amplifier and the scattered light signal waveform corresponding to the foreign matter signal buried in the component can be revealed, regardless of the surface property of the inspection object. It is possible to detect foreign matter.

By providing an optical filter between the scattered light detector and the wafer and reducing the offset value of the DC component by this optical filter, the offset value of the output signal waveform of the scattered light detector can be increased. In addition, since the output signal waveform is saturated in the dynamic range of the amplifier and the scattered light signal waveform corresponding to the foreign matter signal buried in the component can be revealed, the surface property of the object to be inspected is not affected. Therefore, a foreign substance can be detected.

An optical filter is provided between the inspection light irradiation device and the wafer, and the intensity of the inspection light is weakened by the optical filter, whereby the offset value of the DC component is relatively reduced. Therefore, the offset value of the output signal waveform of the scattered light detector is high, and the output signal waveform is saturated in the dynamic range of the amplifier and the scattered light signal waveform corresponding to the foreign matter signal buried in the component is revealed. As a result, foreign matter can be detected regardless of the surface properties of the object to be inspected.

[Brief description of drawings]

FIG. 1 is a block diagram showing a wafer foreign matter inspection apparatus according to an embodiment of the present invention.

2 (a), (b) and (c) are diagrams for explaining the operation thereof.

FIG. 3 is a block diagram showing a wafer foreign matter inspection apparatus that is Embodiment 2 of the present invention.

FIG. 4A and FIG. 4B are diagrams for explaining the operation.

FIG. 5 is a block diagram showing a foreign matter inspection device for a wafer which is Embodiment 3 of the present invention.

[Explanation of sign]

1 ... Wafer (inspection object), 2 ... Foreign matter, 10A, 1
0B ... Wafer particle inspection device, 11 ... Stage device, 1
2 ... Controller, 20 ... Inspection light irradiation device, 21 ... Laser light (inspection light), 22 ... Laser light irradiation device, 23 ...
Condensing lens, 24 ... Galvano mirror, 25 ... Epi-illumination system, 26 ... Oblique illumination system, 30 ... Scattered light detection device, 31 ...
Scattered light, 32 ... Objective lens, 33 ... Relay lens, 34
... scattered light detector, 35 ... amplifier, 36 ... A / D converter,
37 ... Monitor, 38 ... Offset processing circuit, 39 ... Operating device, 40 ... Foreign matter determination device, 41, 42 ... ND filter (optical filter).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Kabara 2-6-2 Otemachi, Chiyoda-ku, Tokyo Inside Nitrate Electronics Engineering Co., Ltd.

Claims (3)

[Claims] 1. A stage device for holding an inspection object, an inspection light irradiation device for irradiating the inspection object with inspection light, and a scattered light detector for detecting scattered light of the inspection light on the inspection object. In the defect inspection apparatus comprising a defect determination device for determining a defect based on the detection result of the scattered light detector, an offset processing circuit is provided in the signal processing circuit of the scattered light detector, The offset processing circuit is configured to reduce the entire offset value of the detection signal due to the difference in reflectance or absorption rate of the object to be inspected and prevent the scattered light detection signal from being saturated in the dynamic range of the amplifier. Defect inspection device characterized by. 2. A stage device for holding an inspection object, an inspection light irradiation device for irradiating the inspection object with inspection light, and a scattered light detector for detecting scattered light of inspection light on the inspection object. In a defect inspection device comprising a defect determination device that determines a defect based on the detection result of the scattered light detector, an optical filter having different transmittance between the scattered light detector and the inspection object. Is provided so that it can be exchanged, and these optical filters are configured to be exchanged according to differences in reflectance, absorptance, etc. of the surface of the object to be inspected. 3. A stage device for holding an inspection object, an inspection light irradiation device for irradiating the inspection object with inspection light, and a scattered light detector for detecting scattered light of the inspection light on the inspection object. And a defect inspection device comprising a defect determination device for determining a defect based on the detection result of the scattered light detector, wherein an optical filter having different transmittance between the inspection light irradiation device and the inspection object. Is provided so that it can be exchanged, and these optical filters are configured to be exchanged according to differences in reflectance, absorptance, etc. of the surface of the object to be inspected.