JPH09138364A - Optical scanning device and foreign body inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a physically stable optical scan by providing a rotary driving means and a light deflecting means which compensate a generated surface deflection error, and rotating the light deflecting means in one body so that a luminous flux scanned body is scanned with luminous flux which has its wave front divided and deflected by the light deflecting means. SOLUTION: A light beam L1 of a linear polarized light wave emitted by a laser light source 25 has its phase modulated into a circular polarized wave, which is reflected by a reflecting mirror 27 and expanded by a beam expander lens system 28, and then made incident on an optical unit 24 as incident luminous flux I0 through a lens 29. The luminous flux I0 has it phase modulated by a λ/4-wavelength plate 23 into a linear polarized wave. Then the wave is reflected by 1st and 2nd reflecting surfaces 11A and 11B of a rotary mirror 11 and made incident on an inspected surface 32A of an inspected substrate 32 again as 1st and 2nd pieces I1 and I2 of reflected luminous flux. At this time, the pieces I1 and I2 of reflected luminous flux make arcuate scans on the inspected surface 32A of the inspected substrate 32 according to the rotation of the optical unit 24 accompanying the driving of a motor 2.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. TECHNICAL FIELD OF THE INVENTION Conventional Technology Problems to be Solved by the Invention Means for Solving the Problems Embodiments of the Invention (1) First Example (1-1) Principle (FIGS. 1A to 3) (1-2) Configuration of the foreign matter inspection apparatus according to the first embodiment (see FIG.
(FIG. 6) (1-3) Operation of the first embodiment (1-4) Effect of the first embodiment (2) Second embodiment (2-1) Principle (FIGS. 7A to 9) ( 2-2) Configuration of the foreign matter inspection apparatus according to the second embodiment (FIG. 1)
0) (2-3) Operation of the second embodiment (2-4) Effects of the second embodiment (3) Other embodiments Effects of the invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device and a foreign substance inspection device, and is suitable for application to a device for detecting the presence or absence of foreign substances adhering to the surface of a large substrate such as a mask for liquid crystal production. is there.

[0003]

2. Description of the Related Art Conventionally, as an optical means for detecting the presence or absence of foreign matter on a substrate in this type of foreign matter inspection apparatus, FIG.
The optical scanning device 1 as shown in (A) and (B) is used. Note that FIG. 11A is a front view and FIG.
(B) is a bottom view. The optical scanning device 1 is composed of a motor 2 fixed in the device and a rotary mirror 3 which is rotated integrally with a drive shaft 2A of the motor 2 in a direction indicated by an arrow a. The rotary mirror 3 has first and second reflecting surfaces 3A and 3B formed of two plane mirrors.
And the second reflecting surfaces 3A and 3B are the drive shaft 2A of the motor 2.
The angles b ₁ and b ₂ are respectively formed with respect to the optical axis n parallel to.

In this case, the incident light beam I ₀ incident along the optical axis n is split into two equal wavefronts by the first and second reflecting surfaces 3A and 3B of the rotary mirror 3 and is reflected. As a result, the first and second reflected light beams I ₁ and I ₂ are separated and proceed. When the optical axis n and the drive axis 2A of the motor 2 are parallel to each other, the first and second reflected light fluxes I ₁ and I _{2 form} angles θ ₁ and θ ₂ with respect to the optical axis n, respectively. These are

(Equation 1)

(Equation 2) It is represented by

[0005]

By the way, the optical scanning device 1 is provided.
In the above, there is a possibility that the drive shaft 2A of the motor 2 may shake the shaft statically or dynamically with respect to the optical axis n. As a result, the drive shaft 2A is deviated in the direction indicated by the arrow c, and the drive shaft 2A is displaced.
When the relative angular deviation between the optical axis n and the optical axis n is δ, the angles θ ₁ and θ ₂ of the first and second reflected light beams I ₁ and I ₂ with respect to the optical axis n are respectively the angle θ ₁ ′, Angle θ ₂ ′ and these change

(Equation 3)

(Equation 4) It is represented by

When the drive shaft 2A of the motor 2 is statically or dynamically shaken in this manner, the drive shaft 2A is driven by the optical axis n.
The angle of reflection 3 of the rotary mirror 3
Surface deflection also occurs in A and 3B. As a result, the angles of the first and second reflected light fluxes I ₁ and I ₂ with respect to the optical axis n may change, and it may not be possible to irradiate the substrate (not shown). There was a problem that was difficult to detect.

The first and second reflected light beams I ₁ and I ₂
Are reflected at the same angle with respect to the drive shaft 2A of the motor 2, for example, in equations (1) and (2),
_When reflecting under the condition that ₁ = θ ₂ ,
It is necessary to independently improve the angle accuracy of the second reflection surfaces 3A and 3B with respect to the optical axis n.

The present invention has been made in consideration of the above points, and physically stable optical scanning is performed on an object to be irradiated with a light beam (object to be inspected), and an object to be irradiated with a light beam to be inspected (object to be inspected) is obtained. It is intended to propose an optical scanning device and a foreign matter inspection device which can deal with a large case and can detect a foreign matter with high accuracy.

[0009]

In order to solve such a problem, according to the present invention, a rotation driving means 2 having a rotation axis 2A and an incident light incident along a first optical axis n parallel to the rotation axis 2A. The light flux I ₀ is divided into a first light flux I ₁ forming a first angle with respect to the first optical axis n and a second light flux I ₂ forming a second angle with respect to the first optical axis n. The wavefront division is performed, and the first light flux I ₁ and the second light flux I ₂ are respectively deflected in the rotation direction of the rotation axis 2A with the center position of the wavefront division as a reference to be incident on the light irradiation target object 32, and further rotated. The first angle is compensated for by a surface wobbling error caused by a change in one or both of the first angle and the second angle based on the relative angular deviation between the axis 2A and the first optical axis n. And the optical deflecting means 11 and 91 for maintaining the second angle at a constant value, and the rotation driving means 2 includes the optical deflecting means 1 The light deflectors 11 and 91 are rotated about the rotation axis 2A so that the first light flux I ₁ and the second light flux I _{2 which} are wavefront-divided and deflected by the light beams ₁ and 91 scan the light beam irradiation object 32. I made it rotate together.

Further, in the present invention, the light source 2 for emitting the light beam L1 in the foreign matter inspection device 20, 100 for inspecting the presence or absence of foreign matter adhered to the inspected surface 32A of the inspected object 32.
5, rotation driving means 2 having a rotation axis 2A, and light flux L1
Of the first optical axis n which is arranged on the optical path of
An incident light beam I ₀ incident along the first optical axis n with a first light beam I ₁ forming a first angle with respect to the first optical axis n and a second light beam forming a second angle with respect to the first optical axis n. The rotation axis 2A is divided into _two light fluxes I ₂ and the center of the wavefront division is used as a reference.
The first light flux I ₁ and the second light flux I ₂ are respectively deflected in the rotation direction of ## EQU1 ## to be incident on the inspection surface 32A of the inspection object 32, and the relative rotation axis 2A and the first optical axis n are relative to each other. Deflection for compensating for a surface wobbling error caused by a change in either or both of the first angle and the second angle based on the effective angle deviation to maintain the first angle and the second angle at constant values. Means 1
1, 91 and the first light flux I ₁ and the second light flux I generated by the foreign matter adhered to the surface 32A of the inspection object 32.
Receiving the _second scattered light, and the light receiving means 51 to 67 for outputting an electric signal corresponding to the intensity of the received scattered light, light receiving means 51
Signal processing means 40 and 41 for detecting foreign matter based on the electric signals supplied from
Are the first light flux I ₁ and the second light flux I _{2 which} are wavefront-divided and deflected by the light deflecting means 11 and 91, and are inspected 32.
The light deflection means 11 and 91 are integrally rotated about the rotation axis 2A so as to scan the surface 32A to be inspected.

Further, in the present invention, the optical scanning device 2
1, 101, the polarization state of the incident light beam I ₀ as the incident light beam I ₀ had it occurred deflected light deflector 11, 91 is a constant polarization state relative Hihikaritaba irradiated (inspection object) 32 A polarization state adjusting means 23 for adjusting the light flux is provided, and the rotation driving means 2 is configured such that the first light flux I ₁ and the second light flux I _{2 which} are wavefront-divided and deflected by the light deflecting means 11 and 91 are irradiated by the light flux irradiation object The optical deflecting means 11 and 91 and the polarization adjusting means 2 centering on the rotation axis 2A so as to scan the (inspection object) 32.
It was made to rotate 3 integrally.

In this way, the incident light beam I ₀ incident along the first optical axis n parallel to the rotation axis 2A forms a first light beam I forming a first angle with respect to the first optical axis n. ₁ and the first optical axis n
With respect to the second light flux I ₂ forming a second angle with respect to, and the rotation axis 2 with the center position of the wavefront division as a reference.
The first light flux I ₁ and the second light flux I ₂ are respectively deflected in the rotation direction of A to be incident on the light flux irradiation object 32, and the rotation axis 2
Based on the relative angular deviation between A and the first optical axis n, a surface wobbling error caused by a change in either or both of the first angle and the second angle is compensated for and the first angle and By providing the light deflecting means 11 and 91 for maintaining the second angle at a constant value, even when static or dynamic shaft wobbling occurs on the rotation shaft 2A of the rotation driving means 2, the first and first The two luminous fluxes I ₁ and I ₂ can be physically and stably scanned with respect to the luminous flux irradiation object (inspection object) 32 without being affected by the axial shake. Further, the light deflection means 11 and 9
Light polarization state adjusting unit 23 for the incident light beam I ₀ had it occurred deflected 1 adjusts the polarization state of the incident light beam I ₀ as a constant polarization state relative Hihikaritaba irradiated (inspection object) 32 By providing the scanning devices 21 and 101, it is possible to cope with the case where the object to be irradiated with the light beam (object to be inspected) is large, and it is possible to accurately detect the foreign matter.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described in detail below with reference to the drawings.

(1) First Embodiment (1-1) Principle Optical scanning in FIGS. 1A and 1B in which parts corresponding to those in FIGS. 11A and 11B are denoted by the same reference numerals. Device 10
Unlike the conventional optical scanning device 1, the first and second reflecting surfaces 11A and 11B, which are two plane mirrors of the rotary mirror 11, are the same with respect to the optical axis n parallel to the drive axis 2A of the motor 2. Angle d of.

FIG. 2 shows an incident light flux I ₀ and a second reflected light flux I ₂ which are incident along the optical axis n when the drive shaft 2A of the motor 2 does not cause axial runout with respect to the optical axis n. Shows the relationship with. In this case, the incident light beam I ₀ is reflected by the first reflecting surface 1
After being reflected by 1A, it is further reflected by the second reflecting surface 11B and travels as a _second reflected light beam I ₂ .

Since the incident light beam I ₀ is parallel to the optical axis n, it forms an angle d with the first reflecting surface 11A, and the second reflected light beam I ₂ makes it with respect to the second reflecting surface 11B. When the angle is e, geometrically the angle e is

(Equation 5) It is represented by Therefore, when the angle formed by the second reflected light flux I ₂ with respect to the optical axis n is θ, the angle θ is

(Equation 6) It is represented by

Here, FIG. 3 shows a case where the drive shaft 2A of the motor 2 statically or dynamically shakes the optical axis n, and the drive shaft 2A is inclined by an angle δ with respect to the optical axis n. Indicates. In this case, when the incident light flux I ₀ parallel to the optical axis n forms an angle d ₁ with the first reflecting surface 11A and the angle between the optical axis n and the second reflecting surface 11B is d _2. The relationship between the angle d ₁ and the angle d ₂ is

(Equation 7) It is represented by Further, the second reflected light flux I ₂ is reflected by the second reflecting surface 1
When the angle formed with respect to 1B is e ₁ , the angle e ₁ is geometrically calculated by the following equation obtained by substituting the equation (7).

(Equation 8) And an angle θ of the second reflected light flux I ₂ with respect to the optical axis n is obtained by substituting the equations (7) and (8)

(Equation 9) It is represented by

As described above, the angle θ of the second reflected light flux I ₂ with respect to the optical axis n is always constant regardless of the value of the inclination angle δ when the drive shaft 2A of the motor 2 is inclined with respect to the optical axis n. It turns out that it shows a value. As a result, even if the drive shaft 2A of the motor 2 statically or dynamically vibrates with respect to the optical axis n, the second reflected light flux I ₂ is affected by the surface wobbling of the second reflecting surface 11B. You don't have to. Further, similarly to the case described above, even when the incident light flux I ₀ is incident on the first reflection surface 11A, the first reflected light flux I ₁ is generated by the first reflection surface 11A.
It is not affected by the surface runout of.

(1-2) Configuration of Foreign Material Inspection Apparatus According to First Embodiment Next, a foreign material inspection apparatus to which the optical scanning device 10 is applied will be described. In the foreign matter inspection device 20 shown in FIG.
Unlike the optical scanning device 10, the optical scanning device 21 is provided with an optical unit 24 including a rotary mirror 11, a box body 22 and a λ / 4 wavelength plate 23 so as to rotate integrally with the drive shaft 2A of the motor 2. . In the optical unit 24, the rotary mirror 11 is fixed to the inner surface of the upper end of the box body 22, and the lower side surface of the box body 22 is provided with λ / from the outside so as to cover a window formed coaxially with the drive shaft 2A. The four-wave plate 23 is fixed.

In this foreign matter inspection apparatus 20, the laser light source 2
The light beam L1 which is a linearly polarized wave emitted from
After being phase-modulated into a circularly polarized wave through the / 4 wavelength plate 26, it is reflected by the reflection mirror 27 and then the beam expander lens system 2
5 and is expanded in the beam expander lens system 25, and then a predetermined aperture angle α is set through the lens 29.
The incident light beam I ₀ is focused on the optical unit 24 via the reflection mirror 30 fixed in the apparatus.

Incident light beam I incident on the optical unit 24
₀ means that the vibration direction of the electric vector is due to the λ / 4 wave plate 23 and the optical axis n and the first or second reflecting surface 11A and 11B.
The phase is modulated into a linearly polarized wave that is orthogonal to the plane Zn ₁ or Zn ₂ including and.

After this, the first and second rotary mirrors 11 are
Of the substrate to be inspected, which is reflected on the reflecting surfaces 11A and 11B of the above and is placed on the stage 31 through the windows formed on the lower surface of the box 22 as the first and second reflected light beams I ₁ and I ₂ , respectively. It is incident on the surface 32A to be inspected 32 as S-polarized wave. At this time, the first and second reflected light fluxes I ₁
And I ₂ scan the surface 32A to be inspected of the substrate 32 to be inspected in an arc shape according to the rotation of the optical unit 24 accompanying the driving of the motor 2.

In the stage 31 on which the substrate 32 to be inspected is placed, an actuator 34 which is driven in synchronization with the motor 33 causes the stage 31 to move in a direction indicated by an arrow x every time the optical unit 24 rotates 180 [°]. To be moved to the first and second reflected light fluxes I ₁
And I ₂ can scan the inspected surface 32A of the inspected substrate 32 over the entire surface.

As shown in FIG. 5, around the stage 31, when the first and second reflected light beams I ₁ and I ₂ scan the surface 32A of the substrate 32 to be inspected, the surface to be inspected is scanned. In order that the scattered light generated in 32A can be received from different spatial directions, the light receiving units 51 to 67 each including a condenser lens and a light receiving element form a plurality of arcs at equal intervals so that the optical scanning line C can be seen obliquely from above. It is installed side by side. Further, a signal processing unit 40 and a control unit 41 for processing the light reception results of these light receiving units 51 to 67 are provided.

At this time, the edges of the pattern in which the first and second reflected light beams I ₁ and I ₂ are formed on the surface 32A to be inspected of the substrate 32 to be inspected are provided at the positions where the respective light receiving portions 51 to 67 are arranged. The scattered light generated when irradiated has a strong directivity, while the scattered light due to the foreign matter spreads in all directions from the foreign matter, and is formed on the inspected surface 32A of the inspected substrate 32. It is selected not to receive scattered light from the edges of the pattern.

The output signals of these light receiving portions 51 to 67 are
As shown in FIG. 6, the signal is supplied to the signal switching unit 70 provided in the signal processing unit 40. The signal switching unit 70 includes the control unit 4
On the basis of the angle information signal S1 representing the rotation angle of the optical unit 24 given from 1, three light receiving parts capable of receiving scattered light from the inspection point corresponding to the rotation angle among the 17 light receiving parts are selected. The selected electric signals S2 to S4 from the selected three light receiving units are supplied to the variable gain amplifiers 71 to 73, respectively.

Incidentally, in reality, only three adjacent light receiving portions can simultaneously receive scattered light from one point (inspection point) on the optical scanning line among the light receiving portions 51 to 67. Therefore, depending on the position of the inspection point depending on the rotation angle of the optical unit 24, three adjacent light receiving sections capable of simultaneously receiving the light from the inspection point are appropriately selected from the 17 light receiving sections.

According to the experimental results, the electric signals S2 to
S4 varies depending on the rotation angle of the optical unit 24, that is, the position of the first or second reflected light flux I ₁ or I ₂ on the optical scanning line C. Therefore, the variable gain amplifiers 71 to 73
Are angle information signals S5 to S7 given from the control unit 41.
By correcting the gains of the electric signals S2 to S4 based on the above, the electric signals S8 to S10 having a substantially constant signal level are obtained without depending on the rotation angle of the optical unit 24.

The electric signals S8 to S10 after gain correction are
The gain variable amplifiers 71 to 73 supply the minimum value selector 74, and the minimum value selector 74 determines the minimum signal level among the signal levels of the electric signals S8 to S10 and controls it as the minimum value signal S15. Supply to the part 41. The control unit 41 specifies the size of the foreign matter on the inspected surface 32A of the inspected substrate 32 based on the minimum value signal S15. By using the minimum value to specify the size of the foreign matter, noise from the edge can be eliminated when the edge of the pattern and the foreign matter coexist.

On the other hand, the electric signals S8 to S1 after the gain correction are made.
0 is supplied from the variable gain amplifiers 71 to 73 to the comparators 75 to 77, respectively. Comparator 75-7
7 compares each of the electric signals S8 to S10 with a predetermined threshold value which is sufficiently high in view of the level of electric noise or optical noise based on the reference voltage 78, so that each of the electric signals S8 to S8.
10 is binarized, and these are binarized signals S11 to S11.
It is supplied to the AND circuit 79 as S13.

The AND circuit 79 outputs the binarized signals S11 to S.
When all 13 are logic "H", that is, when all exceed a predetermined threshold value based on the reference voltage 78, the foreign matter detection signal S14 is output to the control unit 41. The control unit 41 takes in the minimum value signal S15 from the minimum value selector 74 by using the foreign matter detection signal S1 as a trigger, determines the size of the foreign matter based on the minimum signal level obtained from the minimum value signal S15, and further, A foreign substance display signal S16 including the size and shape of the foreign substance along with the position of the foreign substance on the surface 32A to be inspected is sent to the display 80 provided outside to be displayed.

(1-3) Operation of the First Embodiment In the above configuration, in the foreign matter inspection device 20, the light beam L formed by the linearly polarized wave emitted from the laser light source 25 is used.
1 is phase-modulated into a circularly polarized wave by a λ / 4 wave plate 26, and then the optical scanning device 21 is passed through an optical system including a reflection mirror 27, a beam expander lens system 25, a lens 29 and a reflection mirror 30. The drive shaft 2A of the motor 2 and the optical axis n are made incident on the optical unit 24 of FIG.

Then, the incident light beam I ₀ is converted into an optical unit 2
It is converted into a light beam of a linearly polarized wave by the λ / 4 wave plate 23 of 4 and is directed toward the surface 32A to be inspected of the substrate 32 to be inspected at the first and second reflecting surfaces 11A and 11B of the rotary mirror 11. At the same time as firing, the motor 2 is driven to rotate the optical unit 24 to scan the surface 32A to be inspected of the substrate 32 to be inspected with the first and second reflected light beams I ₁ and I ₂ .

Further, at this time, the scattered light generated on the inspected surface 32A of the inspected substrate 32 is received by the light receiving sections 51 to 67 having a plurality of light receiving elements, and these light receiving sections 51 to 67 are received.
The presence or absence of foreign matter is detected in the signal processing unit 40 based on the output of

Further, in the foreign matter inspection device 20, as described above, the vibration direction of the electric vector of the incident light beam I ₀ emitted from the optical scanning device 21 is the optical axis n and the first or second reflecting surface 11A or 11B. Phase-modulated into a linearly polarized wave that is orthogonal to a plane Zn ₁ or Zn ₂ including and, accordingly, the first and second reflected light fluxes I ₁ and I ₂ are rotated at the rotation angle of the optical unit 24 of the optical scanning device 21. Regardless, it always enters the inspection surface 32A of the inspection substrate 32 as an S-polarized wave.

In this case, if the substrate 32 to be inspected is made of a glass material such as a liquid crystal substrate, S
When the P-polarized wave has a higher reflectance than the polarized wave and a pattern made of a metal material is formed on the surface 32A to be inspected of the substrate 32 to be inspected, the edge of this pattern is larger than the S-polarized wave. It is known that the scattered light of the P-polarized wave is more likely to be generated. Therefore, the foreign matter inspection apparatus 20 can inspect foreign matter with higher accuracy than the conventional foreign matter inspection apparatus that does not consider the polarization state of the light beam incident on the inspected surface 32A of the inspected substrate 32. it can.

Further, since the rotary mirror 11 is composed of two plane mirrors of the first and second reflecting surfaces 11A and 11B which are not orthogonal to each other, the drive shaft 2 of the motor 2 is formed.
When static or dynamic axial runout occurs in A, the angles formed by the first and second reflected light beams I ₁ and I ₂ with respect to the optical axis n are both the first and second reflecting surfaces 11A and 11B. Is determined by the angle formed by, and thus always shows a constant value regardless of the degree of deviation of the drive shaft 2A with respect to the optical axis n. As a result, even if the drive shaft 2A of the motor 2 statically or dynamically shakes the optical axis n, the first and second reflected light fluxes I ₁ and I ₂
Can be optically scanned without being affected by the surface runout of the first and second reflecting surfaces 11A and 11B.

(1-4) Effects of the First Embodiment According to the above configuration, the incident light flux I _0, which is a circularly polarized wave, is converted into λ
/ 4 with polarization state converting first and second reflected light beams I ₁ and I ₂ of the constant linearly polarized wave in the wavelength plate 26, to be inspected the first and second reflected light beams I ₁ and I ₂ The λ / 4 wave plate 23 and the rotary mirror 11 are deflected by the rotary mirror 11 so as to be incident on the surface 32A to be inspected of the substrate 32 and rotated by the motor 2 with the optical axis n of the incident light beam I ₀ as the rotation axis 2A. By making the first and second reflected light beams I ₁ and I ₂ scan the inspected surface 32A of the inspected substrate 32 in this way, it is possible to deal with the case where the inspected substrate 32 is large and the accuracy is improved. Foreign matter can be detected well.

Further, since the rotary mirror 11 is composed of the two plane mirrors having the first and second reflecting surfaces 11A which are non-perpendicular to each other, the drive shaft 2A of the motor 2 has a static or dynamic shaft wobbling. Even when it occurs, the first and second reflected light fluxes I ₁ and I ₂ are both determined by the angle formed by the first and second reflection surfaces 11A and 11B, and accordingly, the first and second reflection light fluxes are determined. It is possible to realize a foreign matter inspection apparatus that can perform optical scanning without being affected by surface wobbling of the surfaces 11A and 11B.

(2) Second Embodiment (2-1) Principle Optical scanning in FIGS. 7A and 7B in which parts corresponding to those in FIGS. 1A and 1B are denoted by the same reference numerals. The device 90 is different from the optical scanning device 10 of the first embodiment, and the rotary mirror 11 is composed of four plane mirrors, that is, first to fourth reflecting surfaces 91.
A to 91D, and first and second reflecting surfaces 91A
, 91B form the same angle p with the optical axis n parallel to the drive axis 2A of the motor 2, and the third and fourth reflecting surfaces 91C and 91D form the same plane orthogonal to the optical axis n. ing.

FIG. 8 shows an incident light flux I ₀ and a first reflected light flux I ₁ which are incident along the optical axis n when the drive shaft 2A of the motor 2 does not cause axial runout with respect to the optical axis n. Shows the relationship with. In this case, the incident light beam I ₀ is reflected by the first reflecting surface 9
After being reflected by 1A, it is further reflected by the third reflecting surface 91C and proceeds as the first reflected light flux I ₁ .

Since the incident light beam I ₀ is parallel to the optical axis n, it forms an angle p with the first reflecting surface 11A, whereby the first reflected light beam I ₁ is formed with respect to the third reflecting surface 91C. If the angle is q, geometrically the angle q is

(Equation 10) It is represented by Therefore, when the angle formed by the first reflected light flux I ₁ with respect to the optical axis n is θ, the angle θ is

[Equation 11] It is represented by

Here, FIG. 9 shows a case where the drive shaft 2A of the motor 2 statically or dynamically shakes with respect to the optical axis n, and the drive shaft 2A is inclined by an angle δ with respect to the optical axis n. Indicates. In this case, when the incident light beam I ₀ parallel to the optical axis n makes an angle p ₁ with the first reflection surface 91A, the angle p
₁ is the following formula

(Equation 12) It is represented by In addition, the first reflected light flux I ₁ and the third reflection surface 9
When the angle formed by 1C is q ₁ , the angle q ₁ is

(Equation 13) It is represented by Further, the angle θ of the first reflected light flux I ₁ with respect to the optical axis n is obtained by substituting the equations (12) and (13).

[Equation 14] It is represented by

Thus, the angle θ of the first reflected light flux I ₁ with respect to the optical axis n is always constant regardless of the value of the inclination angle δ when the drive shaft 2A of the motor 2 is inclined with respect to the optical axis n. It turns out that it shows a value. As a result, even if the drive shaft 2A of the motor 2 statically or dynamically shakes with respect to the optical axis n, the first reflected light flux I ₁ will have the first and third reflection surfaces 91A.
And it is not affected by the surface runout of 91C. Further, in the same manner as in the case described above, the incident light beam I ₀ is reflected by the second reflecting surface 9
Even when incident on 1B, the second reflected light flux I ₂ is not affected by the surface runout of the second and fourth reflecting surfaces 91B and 91D.

(2-2) Configuration of Foreign Particle Inspection Apparatus According to Second Embodiment Next, a foreign particle inspection apparatus to which the optical scanning device 90 is applied will be described. In the foreign matter inspection apparatus 100 shown in FIG. 10 in which the same parts as those in FIG.
01 is different from the optical scanning device 90, and is a rotary mirror 91,
Optical unit 1 including box 102 and λ / 4 wave plate 23
03 is provided so as to rotate integrally with the drive shaft 2A of the motor 2.

In the optical unit 103, the box body 102
A rotary mirror 91 is fixed to the inner surface of the upper end of the box body, and a λ / 4 wave plate 23 is fixed to the lower surface of the box body 102 from the outside so as to cover a window formed coaxially with the drive shaft 2A. There is.

In this foreign matter inspection apparatus 100, the light beam L1 which is a linearly polarized wave emitted from the laser light source 25 is
After phase modulation into a circularly polarized wave via the λ / 4 wave plate 26,
The reflected light is reflected by the reflection mirror 27, is incident on the beam expander lens system 25, is enlarged by the beam expander lens system 25, and is then converged via the lens 29 at a predetermined aperture angle α as an incident light flux I _0. The light enters the optical unit 103 via the reflection mirror 30 fixed inside.

The incident optical axis I ₀ incident on the optical unit 103 is determined by the λ / 4 wavelength plate 23 so that the vibration direction of the electric vector is the optical axis n and the third or fourth reflecting surface 91C and 91.
The phase is modulated into a linearly polarized wave that is orthogonal to the plane Zn ₃ or Zn ₄ including D and.

After this, the third or fourth rotary mirror 91 is used.
Of the box body 102 which is reflected by the reflecting surfaces 91C and 91D of the first and second reflected light beams I ₁ and I ₂ , respectively.
S-polarized waves are incident on the surface 32A to be inspected of the substrate 32 to be inspected mounted on the stage 31 through a window formed on the lower side surface of the substrate 31. At this time, the first and second reflected light fluxes I
₁ and I ₂ are optical units 10 associated with the driving of the motor 2.
According to the rotation of 3, the inspection surface 32A of the inspection substrate 32 is scanned in an arc shape.

In the stage 31 on which the substrate 32 to be inspected is placed, an actuator 34, which is driven in synchronization with the motor 33, moves the stage 31 in the direction indicated by the arrow x every time the optical unit 24 rotates 180 [°]. To be moved to the first and second reflected light fluxes I ₁
And I ₂ can scan the inspected surface 32A of the inspected substrate 32 over the entire surface.

Further, as in the case of the first embodiment described above,
Around the stage 31, the first and second reflected light fluxes I ₁
And I ₂ is so as to receive light from different spatial directions and scattered light generated on the inspected surface 32A when scanning the inspected surface 32A of the substrate to be inspected 32, the light receiving portion comprising a condenser lens and a light receiving element A plurality of (not shown) are arranged in an arc shape at equal intervals so that the optical scanning line can be seen obliquely from above.
Further, a signal processing unit and a control unit (both not shown) for processing the light reception result of each of these light receiving units are provided.

(2-3) Operation of the Second Embodiment With the above-mentioned configuration, in the foreign matter inspection device 100, the light beam L1 which is a linearly polarized wave emitted from the laser light source 25 is transmitted by the λ / 4 wavelength plate 26. After phase-modulating it into a circularly polarized wave, the optical axis 103 of the reflecting mirror 27, the beam expander lens system 25, the lens 29, and the reflecting mirror 30 is passed through the optical unit 103 of the optical scanning device 21 to drive the motor 2. 2A and the optical axis n are made to coincide and incident.

Then, the incident light beam I ₀ is converted into an optical unit 1
The λ / 4 wave plate 23 of No. 03 converts the light beam into a linearly polarized light beam, and the third and fourth rotary mirrors 91 convert the light beam.
The reflective surfaces 91C and 91D are fired toward the surface 32A to be inspected of the board 32 to be inspected, and the motor 2
Is driven to rotate the optical unit 103 to scan the surface 32A to be inspected of the substrate 32 to be inspected with the first and second reflected light beams I ₁ and I ₂ .

Further, at this time, scattered light generated on the surface 32A to be inspected of the substrate 32 to be inspected is received by the light receiving sections 51 to 67 having a plurality of light receiving elements, and these light receiving sections 51 to 67 are received.
The presence or absence of foreign matter is detected in the signal processing unit 40 based on the output of

Further, in the foreign matter inspection device 100, as described above, the incident light flux I emitted from the optical scanning device 101 is used.
A plane Zn ₃ or Zn _{4 in which} the vibration direction of the electric vector of ₀ includes the optical axis n and the third or fourth reflecting surfaces 91C and 91D.
Phase-modulated into a linearly polarized wave that is orthogonal to, and accordingly, the first and second reflected light fluxes I ₁ and I ₂ are
Regardless of the rotation angle of the optical unit 103, it is always incident on the inspection surface 32A of the inspection substrate 32 as an S-polarized wave.

Therefore, the foreign matter inspection apparatus 100 inspects foreign matter with higher accuracy than the conventional foreign matter inspection apparatus which does not consider the polarization state of the light beam incident on the surface 32A to be inspected of the substrate 32 to be inspected. can do.

The rotary mirror 11 is composed of four plane mirrors, which are first and second reflecting surfaces 91A and 91B which are non-perpendicular to each other and third and fourth reflecting surfaces 91C and 91D which form the same plane. As a result, when static or dynamic shaft run-out occurs in the drive shaft 2A of the motor 2,
The angles formed by the first and second reflected light beams I ₁ and I ₂ with respect to the optical axis n are both the first and second reflecting surfaces 91A and 91B.
Is determined by the angle formed by, and thus always shows a constant value regardless of the degree of deviation of the drive shaft 2A with respect to the optical axis n.
As a result, even if the drive shaft 2A of the motor 2 statically or dynamically shakes the optical axis n, the first and second reflected light fluxes I ₁ and I ₂ are both Reflective surfaces 91A to 91D
The optical scanning can be performed without being affected by the surface wobbling.

(2-4) Effects of the Second Embodiment According to the above configuration, the incident light flux I _0, which is a circularly polarized wave, is converted into λ.
/ 4 with polarization state converting first and second reflected light beams I ₁ and I ₂ of the constant linearly polarized wave in the wavelength plate 26, to be inspected the first and second reflected light beams I ₁ and I ₂ The λ / 4 wave plate 23 and the rotary mirror 91 are deflected by the rotary mirror 91 so as to be incident on the surface 32A to be inspected of the substrate 32 and rotated by the motor 2 with the optical axis n of the incident light beam I ₀ as the rotation axis 2A. By making the first and second reflected light beams I ₁ and I ₂ scan the inspected surface 32A of the inspected substrate 32 in this way, it is possible to deal with the case where the inspected substrate 32 is large and the accuracy is improved. Foreign matter can be detected well.

Further, the rotary mirror 11 is composed of four plane mirrors composed of first and second reflecting surfaces 91A and 91B which are non-perpendicular to each other and third and fourth reflecting surfaces 91C and 91D which form the same plane. As a result, even when the drive shaft 2A of the motor 2 undergoes static or dynamic shaft wobbling, the first and second reflected light fluxes I ₁ and I ₂ are both the first and second reflecting surfaces 91A. And 91B, and thus the first to fourth reflecting surfaces 91A to 9B.
It is possible to realize a foreign matter inspection apparatus that can perform optical scanning without being affected by 1D surface shake.

(3) Other Embodiments In the above-mentioned embodiment, one stage is provided around the stage 31.
Although the case where seven light receiving units 51 to 67 are provided has been described, the present invention is not limited to this, and a predetermined number of light receiving units other than 17 may be provided. In this case, the substrate to be inspected 3
180 of the optical unit 24 on the surface 32A to be inspected
[°] A predetermined number of light receiving portions are arranged in parallel so that the first and second reflected light beams I ₁ and I ₂ forming the scanning line C corresponding to the rotation amount can be received.

Further, in the above-mentioned embodiment, the case where the rotary mirrors 11 and 91 each have a shape symmetrical with respect to the plane about the optical axis n is described, but the present invention is not limited to this. The shape does not have to be plane-symmetric. In short, the first and second reflected light fluxes I ₁ and I ₂ are wavefront-divided so as to form first and second angles with respect to the optical axis n, and rotation is performed with the center position of the wavefront division as a reference. The inspected surface 3 of the inspected substrate 32 is deflected by deflecting the first and second reflected light fluxes I ₁ and I ₂ in the rotation direction of the axis 2A.
2A, and compensates for a surface wobbling error that occurs when either or both of the first and second angles change based on the relative angular deviation between the rotation axis 2A and the optical axis n, and Various shapes can be applied as long as they are formed so as to maintain the second angle at a constant value.

Further, in the above-mentioned embodiment, the case where the λ / 4 wavelength plate 23 is used as the polarization adjusting means has been described, but the present invention is not limited to this, and the rotary mirror 1 is used.
If also the incident light beam I ₀ had it occurred deflected 1, 91 that can adjust the polarization state of the incident light beam I ₀ as a constant polarization state with respect to the inspected surface 32A of the substrate to be inspected 32 Various ones can be applied.

[0063]

As described above, according to the present invention, the incident light flux incident along the first optical axis parallel to the rotation axis makes a first angle with respect to the first optical axis. The first light beam and the second light beam forming a second angle with respect to the first optical axis are wavefront-divided, and the first light beam and the first light beam in the rotation direction of the rotation axis with reference to the center position of the wavefront division. Both of the first and second angles are deflected based on the relative angular deviation between the rotation axis and the first optical axis by deflecting the two light fluxes and making them incident on the irradiation object (inspection object). Alternatively, by providing an optical deflecting means for compensating a surface wobbling error caused by a change in either one of them and maintaining the first angle and the second angle at a constant value, the rotation axis of the rotation driving means is static or Even when dynamic axial runout occurs, the first and second light fluxes are not affected by the axial runout, and Ibutsu can realize an optical scanning device and foreign matter inspection apparatus capable of physically stable scanned relative (inspection object).

Further, the polarization state adjusting means for adjusting the polarization state of the incident light beam so that the incident light beam deflected by the light deflecting means has a constant polarization state with respect to the light beam irradiation object (inspection object) By being provided in the scanning device, it is possible to realize an optical scanning device and a foreign matter inspection device which can cope with a case where a light beam irradiation object (inspection object) is large and can accurately detect a foreign matter.

[Brief description of the drawings]

FIG. 1 is a side view and a bottom view showing the configuration of an optical scanning device according to a first embodiment of the present invention.

2 is a side view showing a state of a reflected light beam in a normal state of the optical scanning device of FIG.

FIG. 3 is a side view showing a state of a reflected light beam when the optical scanning device of FIG. 1 is shaken.

FIG. 4 is a side view showing the overall configuration of the foreign matter inspection device according to the first embodiment of the present invention.

FIG. 5 is a plan view showing the overall configuration of a foreign matter inspection device according to the first embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of a signal processing unit.

FIG. 7 is a side view and a bottom view showing the configuration of the optical scanning device according to the second embodiment of the present invention.

8 is a side view showing a state of reflected light flux in a normal state of the optical scanning device of FIG.

9 is a side view showing a state of a reflected light beam when the optical scanning device of FIG. 1 is shaken.

FIG. 10 is a side view showing the overall configuration of the foreign matter inspection apparatus according to the first embodiment of the present invention.

FIG. 11 is a side view and a bottom view showing a configuration of a conventional optical scanning device.

[Explanation of symbols]

1, 10, 21, 90, 101 ... Optical scanning device, 2 ...
Motor, 2A ... Drive shaft, 3, 11, 91 ... Rotary mirror, 20, 100 ... Foreign matter inspection device, 22, 102
...... Box, 23,26 ...... λ / 4 wave plate, 24,103
...... Optical unit, 25 ...... Laser light source, 31 ...... Stage, 32 ...... Inspected substrate, 32A ...... Inspected surface, 40
...... Signal processing unit, 41 ...... Control unit, 51 to 67 ...... Light receiving unit.

Claims (10)

[Claims] 1. A rotation driving means having a rotation axis, and an incident light beam incident along a first optical axis parallel to the rotation axis, forms a first angle with respect to the first optical axis. The wavefront division is performed into a first light flux and a second light flux forming a second angle with respect to the first optical axis, and the first light flux and the second light flux in the rotation direction of the rotation axis with reference to the center position of the wavefront division. The one light flux and the second light flux are respectively deflected to be incident on the object to be irradiated with the light flux, and further, the first angle and the first light axis are determined based on a relative angular deviation between the rotation axis and the first optical axis. Optical rotation means for compensating a surface wobbling error caused by a change in both or one of the second angles and maintaining the first angle and the second angle at constant values. Is the first light flux and the second light flux that have been wavefront-divided and deflected by the light deflection means. An optical scanning device characterized in that the light deflecting means is integrally rotated about the rotation axis so that a light beam scans the light beam irradiated object. 2. The light deflecting means comprises a first plane mirror forming a first angle with respect to the first optical axis and a second plane mirror forming a second angle with respect to the first optical axis. 2. The optical scanning device according to claim 1, wherein the first angle and the second angle are the same angle. 3. The light deflecting means comprises a first plane mirror forming a first angle with respect to the first optical axis and a second plane mirror forming a second angle with respect to the first optical axis. It is configured by a combination of three plane mirrors of a plane mirror and a third plane mirror having a reflection surface orthogonal to the rotation axis, and the first angle is the first plane mirror and the third plane of the first light flux. And the second angle is determined based on the reflection angles of the first light flux by the second plane mirror and the third plane mirror. The optical scanning device according to claim 1. 4. The optical scanning device adjusts a polarization state of the incident light flux so that the incident light flux deflected by the light deflecting means has a constant polarization state with respect to the object to be irradiated with the light flux. Polarization rotation adjusting means, the rotation driving means, the first light flux and the second light flux wave-divided and deflected by the light deflecting means, so as to scan the light beam irradiation object, The optical scanning device according to claim 1, wherein the optical deflecting unit and the polarization state adjusting unit are integrally rotated about a rotation axis. 5. The polarization state adjusting means has a predetermined angle corresponding to a polarization state of the incident light flux with respect to a straight line parallel to the incident surface of the light deflection means on which the incident light flux enters and orthogonal to the rotation axis. 5. The optical scanning device according to claim 4, wherein the optical scanning device comprises a wave plate whose optical axis is tilted only in the incident surface of the light deflecting means. 6. A foreign matter inspection apparatus for inspecting the presence or absence of a foreign matter adhered to an inspected surface of an inspected object, a light source for emitting a light beam, a rotation driving means having a rotation axis, and an optical path for the light beam. , An incident light flux incident along a first optical axis parallel to the rotation axis, with respect to the first light flux and the first optical axis forming a first angle with respect to the first optical axis And a second light flux forming a second angle, and deflecting the first light flux and the second light flux in the rotation direction of the rotation axis with reference to the center position of the wavefront division. Incident on the surface to be inspected of the object to be inspected, and further based on a relative angular deviation between the rotation axis and the first optical axis, either or both of the first angle and the second angle. One of the first angle and the second Light deflecting means for maintaining the angle at a constant value, and receiving and receiving scattered light of the first light flux and the second light flux generated by the foreign matter attached to the inspection surface of the inspection object. The rotation driving means includes a light receiving unit that outputs an electric signal according to the intensity of scattered light, and a signal processing unit that detects the foreign matter based on the electric signal supplied from the light receiving unit. The light deflection means is integrated around the rotation axis so that the first light flux and the second light flux, which are wavefront-divided and deflected by the means, scan the surface to be inspected of the object to be inspected. A foreign matter inspection device characterized by being rotated. 7. The light deflecting means comprises a first plane mirror forming a first angle with respect to the first optical axis and a second plane mirror forming a second angle with respect to the first optical axis. 7. The foreign matter inspection apparatus according to claim 6, wherein the first angle and the second angle are the same angle. 8. The light deflecting means comprises a first plane mirror forming a first angle with respect to the first optical axis and a second plane mirror forming a second angle with respect to the first optical axis. It is configured by a combination of three plane mirrors of a plane mirror and a third plane mirror having a reflection surface orthogonal to the rotation axis, and the first angle is the first plane mirror and the third plane of the first light flux. And the second angle is determined based on the reflection angles of the first light flux by the second plane mirror and the third plane mirror. The foreign matter inspection device according to claim 6. 9. The optical scanning device adjusts a polarization state of the incident light flux so that the incident light flux deflected by the light deflecting means has a constant polarization state with respect to the object to be irradiated with the light flux. Polarization rotation adjusting means, the rotation driving means, the first light flux and the second light flux wave-divided and deflected by the light deflecting means, so as to scan the light beam irradiation object, The foreign matter inspection apparatus according to claim 6, wherein the light deflection unit and the polarization state adjustment unit are integrally rotated about a rotation axis. 10. The polarization state adjusting means has a predetermined angle corresponding to a polarization state of the incident light flux with respect to a straight line parallel to the incident surface of the light deflection means on which the incident light flux enters and orthogonal to the rotation axis. The foreign matter inspection apparatus according to claim 9, wherein the foreign matter inspection apparatus is formed of a wave plate having an optical axis inclined only in the incident surface of the light deflector.