JP2003177103A - Apparatus for detecting foreign matter and method for producing dram - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for detecting foreign matters capable of enhancing the detection sensitivity so that flaws or foreign matters smaller than 0.1 μm can be unfailingly detected. <P>SOLUTION: A linearly polarized luminous flux outputted from a laser oscillator 27 passes through a 1/2 wavelength plate 28 and is reflected on a reflection mirror 29, and then, it is condensed onto a semiconductor wafer 2 with a condenser lens 30 to make a small laser spot 31. The 1/2 wave plate 28 rotates centered on an optical axis and works to rotate the direction of polarization of a laser light oscillated with a laser oscillator 27 so that the laser light is adjusted to a P polarized light with respect to the semiconductor wafer 2. Scattered light received by a light receiving system configured by combining a fiber plate 32 and a photomultiplier tube 33 is converted to an electric signal with the photomultiplier tube 33. The electric signal outputted from the photomultiplier tube 33 is amplified with an amplifying section 34 and a computation is performed with a detecting section 35 thereby detecting the presence or absence of foreign matters and flaws and the position thereof. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to foreign matter inspection, and more particularly to a foreign matter inspection apparatus and a foreign matter inspection method for detecting fine foreign matter on a semiconductor wafer or a liquid crystal substrate.

[0002]

2. Description of the Related Art An apparatus used for surface inspection is one in which laser light is applied to the surface of an object to be inspected and the scattered light is received to measure the shape of the surface of the object to be inspected and inspect foreign matters. is there.
As a technique used for these inspections, there is a method called a flying spot method. In this flying spot method, for example, parallel laser light output from a laser light source is focused by a lens system, and then the light beam is irradiated onto a surface of an object to be inspected by an optical scanning means to scan the object to be inspected. The reflected laser light or the transmitted light from the surface is received by the light reception detection system and photoelectrically converted. Then, the electric signal after photoelectric conversion is processed to obtain an inspection result. FIG. 19 is a block diagram of a foreign matter inspection device to which the flying spot method is applied (first
Conventional example). A semiconductor wafer 2 is mounted on the mounting table 1. On the other hand, the laser light output from the laser oscillator 3 is formed into parallel light by the collimator lens 4 and sent to the galvano mirror 5. The galvano mirror 5 scans parallel light and irradiates the surface of the semiconductor wafer 2 at an angle within a predetermined range through a condensing optical system 6. At this time, the condensing optical system 6 shapes the parallel light into a spot light. Therefore, the semiconductor wafer 2
Is scanned with a laser spot light.

A line sensor 7 and light receiving elements 8 and 9 are arranged above the semiconductor wafer 2. The line sensor 7 is arranged at a position for receiving the regular reflection laser light from the semiconductor wafer 2, and the respective light receiving elements 8 and 9 are arranged at a position for receiving the scattered light from the semiconductor wafer 2.
The electric signals output from the line sensor 7 and the light receiving elements 8 and 9 are sent to a measuring circuit 10. The measuring circuit 10 determines from the electric signals whether the surface of the semiconductor wafer 2 is scratched or foreign matter is attached. To do. Next, as another technique, FIG.
There is an inspection device shown in 0 (second conventional example). The semiconductor wafer 2 is placed on the XY table 11. A container 12 is arranged just above the semiconductor wafer 2. The container 12 is formed in a hemispherical shape, and a plurality of light receiving elements 13 are provided on the inner surface thereof. On the other hand, the laser oscillator 3 is arranged above the XY table 11. The laser light output from the laser oscillator 3 passes through the condensing optical system 14, the half mirror 15 and the container 12 and is applied to the semiconductor wafer 2. In this case, the laser light is applied to the semiconductor wafer 2 in the vertical direction. Accordingly, the scattered light from the semiconductor wafer 2 is received by each light receiving element 13. The regular reflection light from the semiconductor wafer 2 reaches the half mirror 15, is reflected by the half mirror 15, passes through the condensing optical system 16, and is received by the light receiving element 17. Then, the electric signal output from each of the light receiving elements 13 and 17 is sent to the measuring circuit 18, and the measuring circuit 18 judges from the respective electric signals whether the surface of the semiconductor wafer 2 is scratched or foreign matter is attached. In this case, the light receiving element 1 that receives the scattered light
The position of scratches or foreign matter on the surface of the semiconductor wafer 2 is measured by the position of 3.

The XY table 11 is controlled and driven by an XY table controller 19 so that laser light scans the semiconductor wafer 2. Further, in the technology disclosed in Japanese Patent Application Laid-Open No. 3-128445, which is a prior application of our company, FIG.
1 and FIG. 22 (third conventional example). As shown in FIG. 21, the semiconductor wafer 2 is placed on the XYθ table 20. On the other hand, a laser oscillator 3 is provided, and a collimator lens 4 and a reflection mirror 21 are sequentially arranged on the optical axis of the laser light output from the laser oscillator 3. A galvano mirror 5 is arranged on the reflection laser optical path of the reflection mirror 21. The laser light scanned by the galvano mirror 5 is condensed by the condensing optical system 22.
The surface of the semiconductor wafer 2 is irradiated with the light through. In this case, the scanning plane of the laser light scanned by the galvanometer mirror 5 is perpendicular to the surface of the semiconductor wafer 2. Further, each line sensor 7 is arranged above the semiconductor wafer 2. These line sensors 7 are parallel to the scanning direction of the laser light and have an angle φ1 (5 ° ≦ φ1 ≦ 40 with respect to the irradiation position of the laser light as shown in FIG.
It is placed at a position to receive scattered light at an angle of °).
The electric signals output from these line sensors 7 are sent to the detection unit 23.

The detecting section 23 has a function of receiving each electric signal and judging from the electric signals whether or not the surface of the semiconductor wafer 2 is scratched or foreign matter is attached. by the way,
In Japanese Patent Application Laid-Open No. 64-3545, page 2, upper left column, line 12 to page 2, upper right column, fourth line, S is formed at a predetermined portion of the patterned wafer surface rotated in a predetermined plane.
(Senkrecht) At the same time as irradiating polarized light, P
A technique is disclosed in which scanning is performed while irradiating (Parallel) polarized light, and the amount of light of a predetermined polarized light component included in the reflected light is detected to detect foreign matter attached to the pattern (fifth conventional example). Although this foreign patent publication does not show a diagram of this foreign matter inspection device, it is shown in FIG.
It is considered that the device shown in FIG. In addition, JP-A-64-3545 and JP-A-5-18889.
There is also an inspection apparatus as disclosed in Japanese Patent Laid-Open No. 6-242242, which includes a plurality of photodetectors, and inspects a foreign substance by obtaining a ratio of the light intensities detected by the photodetectors (sixth conventional example). These devices eliminate the drawbacks of the fifth conventional example.
Further, in JP-A-61-180128 and JP-A-2-284047, a plate-like object is irradiated with polarized light, and the resulting reflected light or scattered light is polarized by a polarizing means and then detected. Then, an inspection apparatus for inspecting foreign matter from these results is also shown (seventh conventional example).

[0006]

The conventional foreign matter inspection apparatus having the above-mentioned structure has the following problems. First, in recent development demands, semiconductors and magnetic materials having higher storage capacities are demanded. With these developed products, even minute scratches and foreign substances, for example, those having a size of about 0.1 μm, are It will affect the quality. On the other hand, the above-mentioned first conventional example and second example
In the conventional example, only a flaw or foreign matter having a size of 0.3 μm or more can be detected on a semiconductor wafer having a mirror surface or an oxide film. Then, on a semiconductor wafer having a surface coating such as a metal film, it is only possible to detect scratches and foreign matters having a size of 0.5 μm or more. That is, in the above-mentioned first conventional example and second conventional example, it is impossible to distinguish between a small part of the specularly reflected light incident on the light receiving elements 8, 9, and 13 and a scratch or foreign matter having a size of about 0.1 μm. Therefore, scratches and foreign matters having a size of about 0.1 μm are also detected as noise. In addition, in the third conventional example, scratches and foreign matters having a size of about 0.1 μm can be detected on a semiconductor wafer having a mirror surface or an oxide film, but since a randomly polarized light is used as a light source,
Since not only the scattered light of scratches or foreign matters of about μm but also the scattered light of the main body of the semiconductor wafer 2 is detected by the light receiving elements 8, 9 and 13, detection of scratches and foreign matters of less than 0.1 μm Has the drawback of being difficult. Then, on a semiconductor wafer having a surface coating such as a metal film, similarly,
There is a drawback that it is difficult to detect scratches and foreign matters having a size of 2 μm or less.

However, in the manufacturing process of semiconductors of the 64M DRAM and later, which is currently under development, it is necessary to detect scratches and foreign matters having a size of about 0.1 μm or less on a semiconductor wafer having a mirror surface or an oxide film. On a semiconductor wafer having a surface coating such as a metal film, it has been necessary to detect scratches and foreign matters having a size of about 0.2 μm or less. Therefore, it has been desired to improve the detection sensitivity of scratches and foreign matter on the semiconductor wafer as compared with the conventional foreign matter inspection apparatus. Further, referring to the fifth conventional example to the seventh conventional example, first, in the fifth conventional example, since it is possible to detect only a wafer having a pattern formed in a single layer on the surface, a multi-layered pattern can be detected. The above pattern cannot be dealt with, and a process of extracting a predetermined polarization component contained in the reflected light must be performed. In the sixth conventional example, a plurality of detectors must be installed, and in addition, a process of obtaining the ratio of the detection intensities of P-polarized light and S-polarized light is required. The method was complicated. In the seventh conventional example, since the reflected light and the scattered light must be polarized by the polarization means and then the foreign matter must be detected for each polarization component, the device configuration is complicated and the signal processing method is complicated. It was.

Further, in the conventional method, as shown in FIG. 24, a detection intensity curve having a good linear characteristic is obtained for a foreign substance having a particle size within a specific range (here, about 0.1 μm to about 0.2 μm). However, the linear characteristic of this detection intensity curve is deteriorated for foreign substances having a larger particle diameter, and it is difficult to specify the exact foreign substance size from the scattered light intensity.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned technical problems, in which the polarization angle of the laser light source and the laser light emitted from the laser light source is variable. A polarization component varying means, a detection system for detecting the scattered light of the laser light applied to the surface of the inspection object, and a foreign matter on the surface of the inspection object based on the intensity of the scattered light detected by this detection system. The foreign matter inspection apparatus is provided with a detection means for detecting the above. Then, when the inspection object is a semiconductor wafer having a mirror surface or a semiconductor wafer having an oxide film, a P-polarized laser beam is irradiated, and when a semiconductor wafer having a metal film is irradiated, an S-polarized laser beam is irradiated. The foreign matter inspection apparatus described above is characterized in that Further, in the foreign matter inspection apparatus, the laser light is configured to be incident on the surface of the inspection object at an angle of 5 ° to 20 °.

Furthermore, in the manufacturing process of a DRAM of 64 M or more, the detecting step of detecting foreign matter on the surface of a semiconductor wafer having a mirror surface, a semiconductor wafer having an oxide film, or a semiconductor wafer having a metal film, etc. Item 7
DRAM using the described foreign matter inspection apparatus
Is a manufacturing method.

[0010]

The foreign matter inspecting apparatus and the foreign matter inspecting method of the present invention improve the detection sensitivity of scratches and foreign matters by a simple configuration using a P-polarized light or S-polarized light for the light source of the third conventional example among the above-mentioned conventional examples and a signal processing method. It is possible to increase scratches and foreign matters of 0.1 μm or less on a semiconductor wafer having a mirror surface or an oxide film, and scratches and foreign matters of 0.2 μm or less on a semiconductor wafer having a surface coating such as a metal film. I am trying to detect it. Also, by switching between P-polarized light and S-polarized light, a P-polarized light is used to detect scratches or foreign matter having a size of 0.1 μm or less on a semiconductor wafer having a mirror surface or an oxide film. The sensitivity is increased. S-polarized light is used to detect scratches and foreign matters having a size of 0.2 μm or less on a semiconductor wafer having a surface coating of a metal film, and the sensitivity of detecting scratches and foreign matters is enhanced. And
By selecting and adopting the detection data of P-polarized light and the detection data of S-polarized light according to the range of the particle size of the foreign matter, the detection sensitivity of scratches and foreign matter is enhanced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention is shown in FIG. 1 and the configuration of this embodiment will be described in detail below. The semiconductor wafer 2 to be inspected is mounted on a mounting table 26 that is a combination of a θ table 24 and an X table 25. Further, the light irradiation system is an Ar + laser oscillator 27 that outputs linearly polarized light.
(Wavelength: 488 nm), a half-wave plate 28, a reflection mirror 29, and a condenser lens 30. The linearly polarized light beam output from the laser oscillator 27 passes through the half-wave plate 28, is reflected by the reflection mirror 29, and is then condensed by the condenser lens 30 onto the semiconductor wafer 2 to form a small laser spot 3.
It is focused so that it becomes 1. The ½ wave plate 28 has a function of rotating the polarization direction of the laser light oscillated by the laser oscillator 27 by rotating it about the optical axis. For 2, P (P
(arallel) Adjust to polarized light. If the polarization angle to be used is fixed (P polarization here), it is 1/2 in advance.
The wave plate 28 may be fixed and provided at a predetermined angle without rotating about the optical axis. The light receiving system is configured by combining a fiber plate 32 and a photomultiplier tube 33. As shown in FIG. 2, the light receiving system is arranged at an angle φ2 (here, φ2 is approximately 25 °) with respect to the laser irradiation position. Further, the light receiving system measures the side scatter caused by the foreign matter.

The scattered light received by the light receiving system is converted into an electric signal by the photomultiplier tube 33. The electric signal output from the photomultiplier tube 33 is amplified by the amplification unit 34, and then calculated by the detection unit 35 to detect the presence or absence of foreign matter or scratches and the position thereof. The semiconductor wafer 2 is linearly moved in the diameter direction of the semiconductor wafer 2 by the X table 25 while being rotated by the θ table 24. As a result, the laser spot 31 spirally scans the entire surface of the semiconductor wafer 2 when the mounting table 26 is controlled by a controller (not shown). Ray
When the spot 31 scans the surface of the semiconductor wafer 2,
Strong scattered light is detected by the light receiving system when a foreign matter or scratch is present in the spot, but weak scattered light (noise) of the semiconductor wafer 2 main body is received by the light receiving system even when there is no foreign matter or scratch in the spot. Detected in the system. Here, the signal component (S component) is detected by the strong scattered light, and the noise component (N component) is detected by the weak scattered light. By the way, the distribution of scattered light due to foreign matter or scratches differs depending on the polarization direction of the irradiation light. Figure 2
FIG. 3 shows the state of the intensity distribution of scattered light due to foreign matters and scratches when the angle φ2 with respect to the laser irradiation position shown in FIG. In the case of P-polarized light, the maximum value of the intensity distribution of scattered light exists in a region close to the surface of the semiconductor wafer 2, that is, in a region with a small angle φ2. On the other hand, S (Senkrec
ht) In the case of polarized light, the maximum value of the intensity distribution of scattered light exists in a region isolated from the surface of the semiconductor wafer 2, that is, a region having a large angle φ 2. The position is detected as a place on the semiconductor wafer 2 where foreign matter or scratches exist.

As shown in FIG. 3, the scattered light of the main body of the semiconductor wafer 2 has the intensity of scattered light in a region separated from the surface of the semiconductor wafer 2 for P-polarized light, S-polarized light and random polarized light, that is, a region having a large angle φ2. Grows larger. Since the unit of light intensity uses relative intensity, it is not specified in FIG. From the result of FIG. 3, when the intensity ratio of the signal component (S component) due to the strong scattered light and the noise component (N component) due to the weak scattered light, that is, S / N 2 of the detection signal of foreign matter or scratch is calculated. , As shown in FIG. In the third conventional example having a configuration similar to that of the present invention, random polarization was applied without considering the polarization direction of the irradiation light. Here, the polarization direction of the randomly polarized light is statistically considered to be approximately in the middle of the polarization directions of the P polarized light and the S polarized light, that is, approximately 45 °. As a result, the intensity distribution of scattered light due to a foreign substance or a scratch is an average of intensity distributions of P-polarized light and S-polarized light as shown in FIG. 3, and does not change abruptly as compared with the case of P-polarized light and S-polarized light alone. . In short, since the maximum part of the intensity distribution of scattered light does not protrude, it is not possible to increase the S / N of the detection signal of foreign matter or a scratch, and therefore it is not possible to improve the detection sensitivity.

From the results shown in FIGS. 3 and 4, there is a characteristic that the intensity of scattered light becomes larger in the region where the weak scattered light of the semiconductor wafer 2 body is separated from the surface of the semiconductor wafer 2, that is, in the region where the angle φ 2 is larger. Random polarization and S due to
Even if the surface of the semiconductor wafer 2 is irradiated with polarized light, the maximum part of the intensity distribution of scattered light is present in a region isolated from the surface of the semiconductor wafer 2, that is, a region having a large angle φ2, and therefore detection of foreign matter and scratches is possible. It can be seen that the S / N of the signal cannot be increased. On the other hand, by irradiating the surface of the semiconductor wafer 2 with P-polarized light, the scattered light of the area close to the surface of the semiconductor wafer 2, that is, the area with a small angle φ2 is received to detect the S / N of a higher detection signal of foreign matter or scratches. You can see that you can get Therefore, if such a foreign matter detection device is configured, the detection sensitivity is increased to
The following scratches and foreign substances can be detected. The semiconductor wafer 2 to be inspected in the present embodiment preferably has a mirror surface or a surface coating such as an oxide film. The present invention is not limited to this first embodiment, and various modifications can be made. In the second embodiment, the scanning of the laser spot 31 is made spiral by moving the semiconductor wafer 2 with the X table 25 while rotating the semiconductor wafer 2 with the θ table 24 as in the first embodiment. I used to go to the semiconductor wafer 2 using the XY table.
May be scanned in the XY directions.

In the third embodiment, the light receiving system in the first embodiment uses the fiber plate 32 to collect scattered light, but the optical system uses a lens instead of the fiber plate 32. It is also conceivable to design a system (not shown) to collect scattered light. Next, a fourth embodiment of the present invention is shown in FIG. 5, and the configuration of this embodiment will be described in detail below. In this embodiment, a laser irradiation system 36, a control system 37,
It is composed of a scanning system 38, a detection system 39, and a signal processing system 40. The laser irradiation system 36 is expanded by an Ar + laser oscillator 41 that outputs linearly polarized light and a beam expander 42, passes through a ½ wavelength plate 43, and is reflected by a reflecting mirror 44 and a condenser lens 45.
The light is focused so as to form an irradiation surface (hereinafter, referred to as a laser spot) 47 having a small spot on the surface of 6. At this time, the ½ wavelength plate 43 is rotated by a motor (not shown) according to a control signal (first signal) from the control circuit 48. Then, by the movement of the ½ wavelength plate 43, the polarization direction of the laser light transmitted through the ½ wavelength plate 43 can be freely changed.

The control system 37 is composed of a computer 49, an interface circuit 50, and a control circuit 48. This control system 37 is a signal (first signal) for changing the polarization direction of the laser light transmitted through the half-wave plate 43.
Then, the detection system 39 outputs a signal (second signal) for selecting the detector 53 and the detector 54 and a signal (third signal) for controlling the movement of the scanning system 38. Scanning system 38
Is a mounting table 51 on which the semiconductor wafer 46 is mounted, and θ
It is composed of a table 52 and an X table 53. Since the laser spot 47 is fixed, the operation of the θ table 52 and the X table 53 scans the entire surface of the semiconductor wafer 46. In particular,
The θ table 52 is rotated at a predetermined speed by the control signal (third signal) from the control system 37, and the X table 53 is rotated.
Moves linearly at a predetermined pitch. By combining these, the laser spot 47 is spirally formed on the semiconductor wafer 4
The entire surface of 6 is scanned. The detection system 39 (light receiving system in the first embodiment) is composed of a detector 54 and a detector 55. The detector 54 includes a fiber plate 56 and a photomultiplier tube 57, and the detector 55 includes a fiber plate 58 and a photomultiplier tube 59. The operations of the fiber plates 56 and 58 and the photomultiplier tubes 57 and 59 are the same as in the first embodiment.

Then, as shown in FIG.
Centering on the irradiation position of 7, the detector 54 is arranged at a position where φ 3 is approximately 35 ° with respect to the surface of the semiconductor wafer 46 and θ 1 is approximately 90 ° with respect to the laser incident surface. Here, the laser incident surface refers to a surface perpendicular to the surface formed by the laser incident light and the laser reflected light. Further, the detector 55 has a diameter of φ4 with respect to the surface of the semiconductor wafer 46.
Is about 80 ° and θ2 is about 135 with respect to the laser incident surface.
It is placed in the ° position. Next, the control system 37 determines whether the semiconductor wafer 46 has a mirror surface, has a surface coating of an oxide film, or has a surface coating of a metal film.
A signal (second signal) for selecting the detector 54 and the detector 55 in 9 is output to operate one of the detector 54 and the detector 55. Here, it is assumed that the type of the semiconductor wafer 46 is automatically identified by the foreign substance inspection apparatus of the present invention, or is input in advance by the measurer. The signal processing system 40 is composed of a hardware section and a software section. The hardware section amplifies the detected signal due to the scattered light from the semiconductor wafer 46 in order to increase the resolution of this signal in the interface circuit 50, and the A / D conversion of this signal, and the result is stored in a computer. The interface circuit 50 is incorporated in the computer 49 and the computer 49. The software section is constituted by a data processing program for calculating the signal (digital value) by the scattered light, which is taken into the computer 49, and discriminating the presence / absence of a foreign substance, the position of the foreign substance, and the size of the foreign substance.

The operation of this embodiment is as follows. First, the type of the semiconductor wafer 46 to be inspected (a semiconductor wafer having a mirror surface, a semiconductor wafer having an oxide film, a semiconductor wafer having a metal film) is registered in the computer 49. The control system 37 includes a laser irradiation system 36, a scanning system 38,
Appropriate control signals are sent to the detection system 39. FIG. 7 shows a specific control flow of the selection process, which will be described in detail below. First, the control signal (first signal) for the laser irradiation system 36 will be described. When the type of the semiconductor wafer 46 to be inspected is registered as a semiconductor wafer having a mirror surface or a semiconductor wafer having an oxide film, the control system 37 outputs a first signal for selecting P-polarized light. Then, the motor (not shown) rotates according to the first signal,
/ 2 The wavelength plate 43 rotates about the optical axis up to a predetermined angle. By this rotation, the polarization state at the laser spot 47 on the semiconductor wafer 46 becomes P-polarized. On the other hand, when the type of the semiconductor wafer 46 to be inspected is registered as a semiconductor wafer having a metal film, the control system 37 outputs a first signal for selecting S-polarized light. Then, the motor (not shown) rotates in accordance with the first signal, and the 1/2 wavelength plate 4
3 rotates about the optical axis up to a predetermined angle. By this rotation, the polarization state at the laser spot 47 on the semiconductor wafer 46 becomes S-polarized.

Next, the control signal (second signal) for the detection system 37 will be described. When the type of the semiconductor wafer 46 to be inspected is registered as a semiconductor wafer having a mirror surface or a semiconductor wafer having an oxide film, the control system 37 outputs a second control signal for operating the detector 54. On the other hand, if the type of the semiconductor wafer 46 that is the object to be inspected is
When registered as a semiconductor wafer having a metal film, the detector 55
The control system 37 outputs a second control signal for operating the. In this way, the detectors 54 and 55 that detect the signal due to the scattered light are automatically switched for each type of the semiconductor wafer 46. When the polarization state and the selection of the detector are completed, the semiconductor wafer 46 is scanned with laser light and inspected for foreign matter. The θ table 52 starts to rotate at a predetermined speed in response to a third control signal from the control system 37. When the θ table 52 starts to rotate, the X table 53 starts linear movement at a predetermined pitch. With this combination, the laser spot 47 spirally scans the surface of the semiconductor wafer 46. At this time, if a foreign matter is present on the irradiation surface of the laser spot 47, the laser light is strongly scattered by the foreign matter. The selected detector 54 or detector 55 detects this scattered light. Then, the signals due to the scattered light are photoelectrically converted by the photomultiplier tube 57 or the photomultiplier tube 59, respectively, and the detection signal is further amplified by the amplifier circuit 60, and passed through the interface circuit 50 to the computer 4
Taken in 9.

Then, the size of the foreign matter is estimated from the intensity of the signal due to the scattered light after being processed by the data processing program,
The existence position of the foreign matter is calculated back from the scanning positions of the θ table 52 and the X table 53. By repeating such scanning, the scattered light is detected while scanning the entire surface of the semiconductor wafer 46, and information such as the number of foreign matters adhering to the surface of the semiconductor wafer 46 and their positions and sizes can be obtained. . Finally, by the operation of the present embodiment described above, detection of foreign matter of 0.1 μm or less in a semiconductor wafer having a mirror surface or a semiconductor wafer having an oxide film, and foreign matter of 0.2 μm or less in a semiconductor wafer having a metal film. It will be explained with concrete data that it is possible to detect. First, the criteria for determining whether or not a foreign substance can be detected using S / N will be described. When the laser spot 47 scans the surface of the semiconductor wafer 46, foreign matter is generated by the laser spot 4
When the light enters the irradiation surface of No. 7, the signal due to the scattered light from the foreign matter is detected. This is a signal component (S). Further, when a foreign substance does not enter the irradiation surface of the laser spot 47 when the laser spot 47 scans the surface of the semiconductor wafer 46, a signal due to scattered light from the surface roughness of the semiconductor wafer 46 is detected. This is a noise component (N).

The ratio of the signal component (S) thus detected to the noise component (N), that is, S / N is the most important parameter that determines the detection sensitivity of the foreign matter inspection apparatus of the present invention.
Generally, the condition that S / N ≧ 3 defined in the pulse practical measurable particle size of JIS standard (JIS B 9924) is satisfied is a criterion for determining that foreign matter can be detected. is there. Therefore, when inspecting the foreign matter on the semiconductor wafer 46, it is desirable to perform the measurement so that the signal component (S) is large and the noise component (N) is small. However, the spatial distribution of the signal component (S) due to the scattered light from the foreign matter and the noise component (N) due to the scattered light from the surface roughness of the semiconductor wafer 46 is determined by the material of the surface of the semiconductor wafer 46 and the laser spot on the semiconductor wafer 46. Since it greatly differs depending on the polarization state at 47, it is difficult to perform measurement so that the signal component (S) is large and the noise component (N) is small unless these two points are taken into consideration. The measured values are shown here. FIG. 8A shows an S / N ratio when a semiconductor wafer having a mirror surface (mirror surface wafer) is irradiated with P-polarized light and a detection system 37.
Is a graph showing a relationship with an angle φ3 formed with respect to the surface of the semiconductor wafer 46. It is assumed that foreign matter having a diameter of 0.1 μm or less adheres to the surface of the semiconductor wafer 46. See also FIG.
(B) is the S / N ratio when irradiated with S-polarized light and the detection system 3
7 is a graph showing the relationship between 7 and the angle φ4 formed with respect to the surface of the semiconductor wafer 46. Here, θ is approximately 45 ° (backscattering) and θ is approximately 90 with respect to the laser incident surface.
° (side scatter), θ shows a state when approximately 135 ° (forward scatter). These graphs show the spatial distribution of the signal component (S) due to the scattered light from the foreign matter on the semiconductor wafer 46 and the noise component (N) due to the scattered light from the surface roughness of the semiconductor wafer 46. There is.

From these measured values, when the semiconductor wafer 46 has a mirror surface, a spatial distribution region having an S / N of 3 or more when measuring a foreign substance on the semiconductor wafer 46 is found, and the S / N in this region is determined. By disposing the detection system 37 at the position showing the peak, even if the semiconductor wafer 46 has a mirror surface, it is possible to detect a foreign substance of 0.1 μm or less with an optimum detection sensitivity. From the measured values in FIGS. 8 (a) and 8 (b),
In the case where the semiconductor wafer 46 has a mirror surface, the detector (that is, the detector 54) is irradiated with P-polarized light and the detector is placed on the semiconductor wafer 46.
It can be seen that if φ3 is arranged at a position of approximately 35 ° with respect to the surface of and the θ is arranged at a position of approximately 90 ° (which becomes θ1) with respect to the laser incident surface, foreign matter can be detected with the best sensitivity. The same measurement as described above is performed on the semiconductor wafer 46 under other conditions. Here, each semiconductor wafer 4
It is assumed that foreign matter having a diameter of 0.2 μm or less is attached to the surface 6. 9A and 9B show the measurement results when the semiconductor wafer 46 has an oxide film (wafer with an oxide film).
The measurement results when the semiconductor wafer 46 has a metal film (wafer with a metal film) are shown in FIGS. 10 (a) and 10 (b). These graphs also show the spatial distribution of the signal component (S) due to the scattered light from the foreign matter on the semiconductor wafer 46 and the noise component (N) due to the scattered light from the surface roughness of the semiconductor wafer 46. There is. Then, these results are analyzed similarly to the case where the semiconductor wafer 46 has a mirror surface.

As a result, when the semiconductor wafer 46 has an oxide film, it is irradiated with P-polarized light and a detector (that is, the detector 5).
4) is about 35 with respect to the surface of the semiconductor wafer 46.
It is placed at a position of θ and θ is about 9 with respect to the laser incident surface.
It can be seen that the foreign object can be detected with the best sensitivity if it is arranged at the position of 0 ° (which becomes θ1). In addition, the semiconductor wafer 4
In the case where 6 has a metal film, S-polarized light is radiated, and a detector (that is, detector 55) is arranged at a position where φ 4 is approximately 80 ° with respect to the surface of the semiconductor wafer 46 and the laser incident surface is It can be seen that the foreign substance can be detected with the best sensitivity by arranging θ at a position of approximately 135 ° (becomes θ2). From the above measurement results, when measuring a semiconductor wafer having a mirror surface or a semiconductor wafer having an oxide film, P-polarized light is irradiated and detection is performed using the detector 54, and when measuring a semiconductor wafer having a metal film. Irradiates S-polarized light to the detector 55
Since it is clear that it is preferable to perform the detection by using, the polarization state and the detectors 54 and 55 are automatically selected according to the type of the semiconductor wafer 46 by the above-described configuration so that the type of the semiconductor wafer 46 can be changed. Instead, the foreign matter can be detected with the best sensitivity.

Here, as a modification of the fourth embodiment described in detail above, the laser spot 47 is scanned by the X table 53 while rotating the semiconductor wafer 46 by the θ table 52 as in the fourth embodiment. Although the semiconductor wafer 46 is spirally moved by moving the semiconductor wafer 46, it is possible to scan the semiconductor wafer 46 in the XY directions by using an XY table (fifth embodiment). Further, in the fourth embodiment, the detection system 39 uses the fiber plates 56 and 58 to collect scattered light, but an optical system (not shown) that uses lenses instead of the fiber plates 56 and 58. It is also conceivable to collect scattered light by using (6th embodiment).
The above is summarized in [Table 1] below.

[Table 1] By the way, in the fourth, fifth, and sixth embodiments, the detection system 39 does not use the two detectors 54 and 55, but measures one detector by moving means (not shown). There is no problem even if the position is moved in the φ direction or the θ direction depending on the type of the target semiconductor wafer. A plurality of detectors in which φ and θ are set to appropriate angles according to the type of the semiconductor wafer 46 may be used.
Φ and θ may be variable depending on the type of the semiconductor wafer to be measured. That is, φ and θ are not limited to the above numerical values. This is because in the above embodiment, side scattered light is used when measuring a semiconductor wafer having a mirror surface or a semiconductor wafer having an oxide film, and forward scattered light is used when measuring a semiconductor wafer having a metal film. However, it is also possible to change the type of scattered light for measurement (forward scattered light, side scattered light, back scattered light) for measurement on other types of semiconductor wafers.

Further, not only φ and θ but also polarized light is P polarized light and S polarized light.
It is not limited to polarized light. It is also conceivable to change the polarization angle of the polarized light for measurement on other types of semiconductor wafers. In short, according to the foreign matter detecting apparatus of the present invention, various kinds of semiconductor wafers can be measured without being limited to the case where the semiconductor wafer has a mirror-finished semiconductor wafer, an oxide film, or a metal film. Next, the incident angle of the irradiation light with respect to the semiconductor wafer will be described by taking the seventh embodiment of the present invention as an example. First, a schematic configuration diagram of a seventh embodiment of the present invention is shown in FIG. 11, and the configuration of the present embodiment will be described in detail below. This embodiment comprises a laser irradiation system 61, a scanning system 62, a detection system 63, and a signal processing system 64. The laser irradiation system 61 includes a laser oscillator 65 that outputs linearly polarized light, a beam expander 66, and a polarization beam splitter (Polarizing Beam S).
Plitter: Hereinafter, referred to as PBS) 67, a reflection mirror 68, and a condenser lens 69. Here, the light beam emitted from the laser oscillator 65 is expanded by the beam expander 66, and is separated into P-polarized light and S-polarized light by the PBS 67. Both the P-polarized light and the S-polarized light are condensed as laser spots 71 and 72 on the surface of the semiconductor wafer 70 by the reflection mirrors 68 and the condenser lenses 69 and 69, respectively.

As shown in FIGS. 12 and 13, both the P-polarized light flux and the S-polarized light flux are incident on the surface of the semiconductor wafer 70 at an angle φ 5 of about 5 ° to about 20 °. Then, the laser irradiation system 61 is set. At this time P
Both the polarized light beam and the S-polarized light beam are blocked from each other by the shutter 73 because they do not affect the detection. The scanning system 62 includes a mounting table 74 on which the semiconductor wafer 70 is mounted, a θ table 75, and an X table 76. Since both the laser spots 71 and 72 of the P-polarized light flux and the S-polarized light flux are fixed, the entire surface of the semiconductor wafer 70 is scanned by the operation of the θ table 75 and the X table 76. That is, the θ table 75 rotates at a predetermined speed, and the X table 76 linearly moves at a predetermined pitch, so that the entire surface of the semiconductor wafer 70 is spirally scanned.
The shutter 73 is positioned between the detector 77 and the detector 78 even when the semiconductor wafer 70 is scanned. The detection system 63 is composed of a detector (first detector) 77 and a detector (second detector) 78. Each detector 7
7. 78 collects the scattered light generated from the semiconductor wafer 74 by the fiber plates 79 80, and detects the scattered light by the photomultiplier tubes 81 82. Here, the detector 77 is arranged so as to detect scattered light from the laser spot 71, and the detector 78 is arranged so as to detect scattered light from the laser spot 72.

As shown in FIG. 12, the detector 77 is arranged at an angle φ 6 of about 10 ° to about 50 ° with respect to the surface of the semiconductor wafer 70 about the laser spot 71 formed by the P-polarized light beam, and the detector 77 Θ 3 is arranged at an angle of approximately 70 ° to approximately 110 ° with respect to the laser incident surface of the light flux. On the other hand, as shown in FIG. 13, φ7 is arranged at an angle of approximately 10 ° to approximately 20 ° with respect to the surface of the semiconductor wafer 70 centering on the laser spot 72 formed by the S-polarized light beam, and is formed on the laser incident surface by the S-polarized light beam. On the other hand, θ4
Are arranged at an angle of approximately 115 ° to approximately 155 °.
The signal processing system 64 is composed of a hardware section and a software section. The hardware section amplifies the detected signal due to the scattered light from the semiconductor wafer 70 in order to increase the resolution of this signal in the interface circuit 84, and the A / D conversion of this signal, and the result is converted to a computer. An interface circuit 84 to be taken in by 85 and a computer 85. The software section is constituted by a data processing program for calculating a signal (digital value) by the scattered light, which is taken into the computer 85, and discriminating presence / absence of foreign matter, position of foreign matter, and size of foreign matter.
The computer 85 also controls the scanning system 62 by a control unit (not shown).

The operation of this embodiment is as follows. First, the laser light emitted from the laser oscillator 65 is the PBS 6
The light beam is divided into a P-polarized light beam and an S-polarized light beam by 7, and the angle φ 5 is about 5 ° to about 20 with respect to the surface of the semiconductor wafer 70 which is the object to be inspected by the reflection mirrors 68 and the condenser lenses 69. The laser spots 71 and 72 are formed by being incident at an angle of °. Here, φ5 is approximately 5 ° to approximately 2
The reason why the angle is 0 ° is that scattered light is generated from the surface of the semiconductor wafer 70 in which no foreign matter exists due to the minute roughness (surface roughness) generated on the surface of the semiconductor wafer 70. This is detected as a noise component (noise). In order to suppress this noise component and improve S / N, the incident angle φ5 of the laser beam is smaller than the incident angle φ5 of the laser beam is large (about 60 ° to 80 ° with respect to the surface of the semiconductor wafer 70). (Semiconductor wafer 7
This is because 5 ° to 20 ° with respect to the surface of 0) is better. A schematic diagram is shown in FIG. On the other hand, the semiconductor wafer 70 is mounted on a mounting table 74, the θ table 75 rotates at a predetermined speed, and the X table 76 linearly moves at a predetermined pitch, so that the entire surface of the semiconductor wafer 70 is laser-scanned. The spots 71 and 72 scan the surface of the semiconductor wafer 70 in a spiral shape.

At this time, if a foreign substance exists on the irradiation surface of the laser spots 71 and 72, the laser beam is strongly scattered by the foreign substance. The scattered light generated in the laser spot 71 by the P-polarized light flux is detected by the detector 77, and the scattered light generated in the laser spot 72 by the S-polarized light flux is detected by the detector 78. The signals due to the scattered light detected in this way are respectively converted into photomultiplier tubes 81.8.
The signal is photoelectrically converted by 2, and the detection signal is further amplified by the amplifier circuit 83, and is taken into the computer 85 via the interface circuit 84. Then, the size of the foreign substance is estimated from the intensity of the signal due to the scattered light processed by the data processing program, and the existing position of the foreign substance is calculated back from the scanning positions of the θ table 75 and the X table 76. By repeating such scanning, scattered light is detected while scanning the entire surface of the semiconductor wafer 70, and information such as the number of foreign matters adhering to the surface of the semiconductor wafer 70 and their positions and sizes can be obtained. . At this time, when the thickness of the metal film formed on the surface of the semiconductor wafer 70 is about 400 nm, the diameter of the foreign matter attached to the surface of the semiconductor wafer 70 is about 0.2 μm.
The foreign matter smaller than m is specified by the signal from the detector 77. Further, in this case, the foreign matter having a diameter of approximately 0.2 μm or more is specified by the signal from the detector 78.

In addition, if the surface of the semiconductor wafer 70 is a mirror surface or if an oxide film is formed on the surface of the semiconductor wafer 70, the diameter of the foreign matter adhering to the surface of the semiconductor wafer 70 is less than about 0.1 μm. Foreign matter is identified by a signal from the detector 77. Further, the diameter in this case is approximately 0.
The foreign matter of 1 μm or more is specified by the signal from the detector 78. Since the metal film has a larger surface roughness, it also has a larger noise component and a lower S / N. Therefore, the diameter of the detectable foreign matter also becomes large. Here, the reason for using the laser light having the different polarization angle depending on the size of the foreign matter attached to the surface of the semiconductor wafer 70 will be described with reference to FIGS. 15 and 16. FIG. 15 shows a light interference phenomenon in a space on the surface of the inspection object when a laser is incident on the surface of the inspection object. The incident light is reflected by the surface of the object to be inspected, but at this time, the incident light and the reflected light interfere with each other, and the interference wave (interference light) is a standing wave in the interference region (hatched portion) shown in FIG. Therefore, if a foreign matter exists in the standing wave region, the foreign matter scatters the standing wave light. Since the scattered light intensity is proportional to the light intensity of the standing wave, the larger the light intensity of the standing wave, the easier the scattered light can be detected.

However, the light intensity of the standing wave (standing wave intensity)
Changes periodically as shown in FIG. 15 depending on the height from the surface of the inspection object (distance in the Z direction). This change in light intensity is magnified to show an Ar + laser (wavelength: 488 nm) on a semiconductor wafer (Si wafer) whose surface has a mirror surface in FIG.
The case of irradiation with is shown as an example. From FIG. 16, the standing wave intensity due to the incidence of P-polarized light is strong in the region up to approximately 0.2 μm from the surface of the inspection object, and the S-polarized light is incident in the region higher than approximately 0.2 μm. It can be seen that the standing wave intensity due to is strong. From this result, in a Si wafer having a mirror surface, a foreign substance having a diameter of less than about 0.2 μm attached to the surface of the wafer is specified by a signal of scattered light by P-polarized light. The diameter in this case is approximately 0.2.
Foreign matter having a size of μm or more is specified by a signal of scattered light due to S-polarized light. The computer 85 selects the detection signal. Even when a metal film is formed on the surface of the Si wafer or an oxide film is formed on the surface of the Si wafer, only the threshold value of the diameter of the foreign matter adhering to the surface of the wafer is different. Whether the reference data is based on P-polarization or S
There is no change in the work of determining whether it is based on polarization.

The laser used is not an Ar + laser but a He-Cd laser (wavelength: 442 nm) or He.
Even when other types of lasers such as -Ne laser (wavelength: 633 nm) are used, the threshold of the diameter of the foreign matter is different because the period of the standing wave intensity distribution that depends on the laser wavelength changes. , There is no change in processing itself. Here, when arranging the detectors, the angular arrangement as shown in FIGS. 12 and 13 is used as described above. The reason is that the spatial distribution characteristic of scattered light depends on the size of the foreign matter to be detected. Is different. That is, when the diameter of the foreign substance is smaller than the above-mentioned threshold value, the detector 81 has a diameter φ6 of about 10 with respect to the surface of the semiconductor wafer 70 centered on the laser spot 71 by the P-polarized light flux as shown in FIG. The angle θ3 is set to an angle of approximately 50 ° (near the surface), and θ3 is set to an angle (side scattering) of approximately 70 ° to approximately 110 ° with respect to the laser incident surface of the P-polarized light beam. This is because scattered light is strongly generated in these directions. On the other hand, as shown in FIG. 13, φ 7 is about 10 ° with respect to the surface of the semiconductor wafer 70 centering on the laser spot 72 formed by the S-polarized light beam.
To about 20 ° (near the reflected light) (since the incident angle φ 5 is about 10 ° to about 20 °), S
Θ4 is approximately 1 for the laser incident surface due to the polarized light beam.
It is arranged at an angle of 15 ° to about 155 ° (forward scattering). This is also because scattered light is strongly generated in these directions.

Here, the lower limit of the size of the angles φ6 and φ7 is about 10 ° because the size of the detector is taken into consideration, and if possible, a smaller angle (about 5).
It is desirable that it is about (°). The upper limit of the angle of θ 4 is about 155 ° in order to avoid specular reflection light, and ideally 180 ° is desirable. In addition, according to the data collected in this manner, a detection intensity curve with good linear characteristics is obtained as shown in FIG. 17, so that the particle size of the foreign matter can be accurately determined from the detection intensity curve. This will be described with reference to FIG. In FIG. 18 (a), the diameter of the surface of the object to be inspected is 0.1 μm (as foreign matter A), 0.4 μm
It indicates that there is a foreign matter (denoted as foreign matter B) and 0.6 μm (denoted as foreign matter C). As a result of scanning the laser spot, FIG. 18B shows a scattered light signal due to incidence of P-polarized light detected by the detector 77.
(C) shows a scattered light signal detected by the detector 78 due to incidence of S-polarized light. 18 (b) and 18 (c), the signal A is used to detect a foreign substance having a diameter of 0.1 μm, but the signals B and C are used to detect a foreign substance having a diameter of 0.4 μm and a diameter of 0.6 μm, respectively. It is understood that it is better to use the signal B ′ and the signal C ′, respectively, instead of using them (FIG. 1).
8 (d)).

The above is summarized in Table 2 below.

[0035]

[Table 2] Here, as in all of the above examples,
He-Cd laser (wavelength: not Ar + laser)
442 nm) or He-Ne laser (wavelength: 633n)
Other types of lasers such as m) can also be used. Instead of using a laser that outputs linearly polarized light, a polarizer that outputs random polarized light may be combined with a polarizer to generate P-polarized light or S-polarized light. Further, the light receiving element may be replaced by a semiconductor photosensor or the like instead of the photomultiplier tubes 33, 57, 59, 81, 82. In addition, the object to be inspected is a semiconductor wafer as an example, but the object to be inspected is not limited to this,
The foreign matter inspection device of the present invention can be used for a liquid crystal substrate or one having a curved surface portion. The reason is that even if it is a curved surface when viewed macroscopically, it becomes a flat surface when viewed microscopically. Therefore, by reducing the spot diameter of the laser spots 31, 47, 71, 72, the curved surface to be inspected can be made similar to a flat surface. This is because it can be inspected.

[0036]

According to the present invention, it is possible to increase the detection sensitivity of foreign matter. Further, according to the present invention, it becomes possible to detect a foreign substance or the like which has been difficult to detect in the conventional semiconductor manufacturing.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a foreign matter inspection device according to a first embodiment of the present invention.

FIG. 2 is a side view showing a positional relationship between a fiber plate and a photomultiplier tube and a semiconductor wafer in the foreign matter inspection apparatus according to the first embodiment of the present invention.

FIG. 3 is a graph showing the relationship between the arrangement angle of the light receiving system and the intensity of scattered light in the foreign matter inspection apparatus according to the first embodiment of the present invention.

FIG. 4 is a graph showing the arrangement angle of the light receiving system and the S / N of the foreign matter detection signal in the foreign matter inspection apparatus according to the first embodiment of the present invention.

FIG. 5 is a schematic configuration diagram showing a foreign matter inspection device according to a fourth embodiment of the present invention.

FIG. 6 is a schematic diagram showing a positional relationship among detectors, a laser incident surface, and a semiconductor wafer in a foreign matter inspection apparatus according to a fourth embodiment of the present invention.

FIG. 7 is a flowchart showing a flow of processing for selecting a polarization state and a detector depending on the type of a semiconductor wafer (inspection object) in the foreign matter inspection apparatus according to the fourth embodiment of the present invention.

FIG. 8 is a graph showing the arrangement angle of the detector and the S / N of the foreign matter detection signal when the mirror surface wafer is measured by the foreign matter inspection apparatus according to the fourth embodiment of the present invention.

FIG. 9 is a graph showing the arrangement angle of the detector and the S / N of the foreign matter detection signal when the wafer with an oxide film is measured by the foreign matter inspection apparatus according to the fourth embodiment of the present invention.

FIG. 10 is a graph showing the arrangement angle of the detector and the S / N of the foreign matter detection signal when the wafer with metal film is measured by the foreign matter inspection apparatus according to the fourth embodiment of the present invention.

FIG. 11 is a schematic configuration diagram showing a foreign matter inspection device according to a seventh embodiment of the present invention.

FIG. 12 is a schematic diagram (1) showing the positional relationship among the detector, the laser incident surface, and the semiconductor wafer in the foreign matter inspection apparatus of the seventh embodiment of the present invention.

FIG. 13 is a schematic view (2) showing the positional relationship among the detector, the laser incident surface, and the semiconductor wafer in the foreign matter inspection apparatus of the seventh embodiment of the present invention.

FIG. 14 is a graph showing the relationship between the intensity of scattered light and the inspection time when the incident angle of laser light is large and when the incident angle of laser light is small in the foreign matter inspection apparatus according to the first embodiment of the present invention.

FIG. 15 is a schematic diagram showing interference of light by incident light and reflected light on the surface of a semiconductor wafer.

FIG. 16 is a graph showing the relationship between the distribution of standing wave intensity on the surface of a semiconductor wafer and the diameter of a foreign substance.

FIG. 17 is a graph showing the diameter of a foreign substance, the intensity of scattered light, and the selection of a detector in the foreign substance inspection apparatus according to the seventh embodiment of the present invention.

FIG. 18 (a) is a schematic view showing the sizes of the foreign matters A to C in the foreign matter inspection apparatus of the seventh embodiment of the present invention,
(B) is a graph showing the relationship between the output signal of the first detector and the inspection time for foreign matter A to foreign matter C, and (c) is the foreign matter A
To a graph showing the relationship between the output signal of the second detector and the inspection time for the foreign matter C, and (d) a graph showing the relationship between the foreign matter detection result for the foreign matter A to the foreign matter C and the inspection time.

FIG. 19 is a schematic configuration diagram showing a foreign matter inspection apparatus of a first conventional example.

FIG. 20 is a schematic configuration diagram showing a foreign matter inspection device of a second conventional example.

FIG. 21 is a schematic configuration diagram showing a foreign matter inspection device of a third conventional example.

FIG. 22 is a side view showing a positional relationship between a line sensor and a semiconductor wafer in a foreign matter inspection apparatus of a fourth conventional example.

FIG. 23 is a schematic configuration diagram showing a foreign matter inspection apparatus of a fifth conventional example.

FIG. 24 is a graph showing the relationship between the diameter of a foreign substance and the intensity of scattered light in a conventional foreign substance inspection device.

[Explanation of symbols]

1.26.51.74 ... Mounting table 2.46.70 ... Semiconductor wafer 3, 27, 41, 65 ... Laser oscillator 4.66 ... Collimating lens 5 ... Galvo mirror 6 ・ 14 ・ 16 ・ 22 ... Focusing optical system 7 ... Line sensor 8/9/13/17 ... Light receiving element 10 ・ 18 ... Measuring circuit 11 ... XY table 12 ... Container 15 ... Half mirror 19 ... XY table control device 20 ... XYθ table 21.29.44 ... Reflective mirror 23.35 ... Detection unit 24 ・ 52 ・ 75 ... θ table 25.53.76 ... X table 28 ・ 43 ... 1/2 wave plate 30, 45, 69 ... Condensing lens 31, 47, 71, 72 ... Laser spot 32, 56, 58, 79, 80 ... Fiber plate 33.57.59.81.82 ... Photomultiplier tube 34 ... Amplifying unit 36.61 ... Laser irradiation system 37 ... Control system 38 ・ 62 ... Scanning system 39 ・ 63 ... Detection system 40/64 ... Signal processing system 42.66 ... Beam expander 48 ... Control circuit 49.85 ... Computer 50/84 ... Interface circuit 54.55.77.78 ... Detector 60 ・ 83 ... Amplification circuit 67 ... Polarizing beam splitter 68 ... Reflective mirror 73 ... Shutter

Continued front page    F term (reference) 2G051 AA51 AB01 BA10 BA11 BB01                       CA02 CA06 CA07 CB05 DA08                       EA12                 4M106 AA01 AA07 AB07 BA05 CA41                       DB02 DB08 DB14

Claims (8)

[Claims] 1. A laser light source, a polarization component varying means for varying a polarization angle of laser light emitted from the laser light source, and a detection system for detecting scattered light of the laser light irradiated on the surface of the object to be inspected. And a detection unit for detecting foreign matter on the surface of the object to be inspected based on the intensity of the scattered light detected by the detection system. 2. The foreign matter inspection apparatus according to claim 1, wherein the laser light source emits an Ar + laser. 3. The foreign matter inspection apparatus according to claim 1, wherein the laser light source emits a He—Cd laser. 4. The foreign matter inspection apparatus according to claim 1, wherein the laser light source emits a He—Ne laser. 5. The foreign matter inspection apparatus according to claim 1, wherein the detection system includes a fiber plate and a photomultiplier tube. 6. When the object to be inspected is a semiconductor wafer having a mirror surface or a semiconductor wafer having an oxide film, a P-polarized laser beam is emitted, and when a semiconductor wafer having a metal film is irradiated, an S-polarized laser beam is emitted. The foreign matter inspection apparatus according to claim 1, wherein the foreign matter inspection apparatus is configured to irradiate. 7. The foreign matter inspection apparatus according to claim 1, wherein the laser light is configured to be incident on the surface of the inspection object at an angle of 5 ° to 20 °. 8. A detection process for detecting foreign matter or the like on a surface of a semiconductor wafer having a mirror surface, a semiconductor wafer having an oxide film, or a semiconductor wafer having a metal film in a manufacturing process of a DRAM of 64 M or more. Item 7. A method for manufacturing a DRAM, characterized by using the foreign matter inspection device according to item 7.