JP3406951B2 - Surface condition inspection device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for inspecting a surface condition, which is used as an object surface to be inspected, such as a reticle or a photomask on which a circuit pattern is formed in a semiconductor device manufacturing apparatus. It is suitable for accurately inspecting a convex member as a defective portion such as dust when it is attached.

[0002]

2. Description of the Related Art Conventionally, the surface condition of an object surface, for example, whether or not a convex member as a defective portion such as dust or dust adheres to the surface is scanned by a light beam such as a laser beam, Various surface state inspection devices have been proposed which inspect the presence or absence of a convex member by inspecting scattered light generated from the convex member.

Generally, when a convex member such as dust or dust adheres to the surface of an object, scattered light is generated by the convex member when scanning with a light beam. At this time, depending on the size of the convex member, The amount of scattered light generated from it is different. In the conventional surface condition inspection apparatus, the presence or absence of a convex member and its size are detected by detecting the magnitude of a signal based on scattered light received by a light receiving element.

[0004]

In a conventional surface condition inspection apparatus for inspecting a surface condition by scanning an object with a light beam and detecting scattered light generated from the object at that time, for example, if the surface of the object is When the surface is rough or has a large surface roughness, scattered light is also generated from a normal region other than the convex member. Therefore, even if the light receiving element is simply arranged in a region that does not receive specularly reflected light and only scattered light is detected, scattered light from a normal region will be received, and it will be present on the surface. There is a problem that it is difficult to accurately detect only the scattered light from the protruding member.

In particular, when the convex member is small and the scattered light generated by the convex member is small, the S / N ratio of the detection signal deteriorates, and it may not be possible to accurately detect the presence or absence of the convex member. .

Besides, the intensity of the scattered light generated from the convex member attached to the object also differs depending on the size of the convex member and the amount of projection protruding from the surface of the object. Therefore, even if the amount of scattered light obtained from the light receiving element is detected, it is difficult to immediately detect the size of the convex member and the amount of protrusion thereof.

According to the present invention, the surface of an object is scanned with a light beam, and scattered light generated from a convex member as a defective portion such as dust or dust adhering to the surface is appropriately arranged in space. It is an object of the present invention to provide a surface state inspection device capable of accurately detecting the convex member without being affected by the roughness and non-uniformity of the surface of the object by using the signal obtained from.

[0008]

According to another aspect of the present invention, there is provided a surface condition inspection apparatus, wherein when a scanning means scans an object using a light beam from a light source means, the scanning line on the object is caused by the light beam. A light receiving element is provided in the space opposite to the incident side of the light beam with respect to the scanning plane formed by the tangent line at the scanning point on the object by the light beam, and the light beam is applied to the object. When the light beam is incident on the scanning plane, a light shielding unit for shielding the light beam emitted in the space on the side opposite to the light beam incident side is provided, and the light receiving element is arranged to shield the light beam from the scanning plane from the scanning plane. Characterized by detecting scattered light generated from a convex member on the object protruding into the space on the incident side, and inspecting a surface state on the object using an output signal from the light receiving element. There is. The invention of claim 2 is characterized in that, in the invention of claim 1, the light shielding means is a knife edge parallel to the scanning line.
The surface condition inspection apparatus according to the invention of claim 3 uses the light beam from the light source means to scan the object by the scanning means, and the scanning line on the object by the light beam and the object by the light beam. The scanning plane formed by the tangent line at the scanning point of 1) is provided with a light receiving element in the space on the incident side of the light beam, and when scanning the object with the light beam, A light-shielding means is provided, which comprises a knife edge parallel to the scanning line for preventing a light beam emitted into the space on the light beam incident side with respect to the scanning plane from entering the light receiving element, The light receiving element detects scattered light generated from a convex member on the object projecting into the space on the incident side of the light beam with respect to the scanning plane, and the output signal from the light receiving element is used to detect the scattered light on the object. Characterized by inspecting the surface condition of That. The invention of claim 4 is characterized in that, in the invention of claim 1, 2 or 3, the object is a cylindrical object, a sheet-like transparent object or a plate-like transparent object.

The surface condition inspection method according to the invention of claim 5 claims
The surface condition inspection device according to any one of items 1 to 4 is used to inspect a surface condition on an object.

According to a sixth aspect of the present invention, there is provided a convex amount measuring device according to the first aspect.
Using the surface condition inspection device according to any one of
It is characterized in that the convex amount of the convex member attached to the object is measured. The convex amount measuring device according to the invention of claim 7 uses the light beam from the light source means to scan the object with the scanning means.
When scanning, scanning on the object by the light beam
Line and tangent line at the scanning point on the object by the light beam
The incident side of the light beam with respect to the scanning plane formed by
A light receiving element is provided in the space on the opposite side of the
Projecting into the space on the incident side of the light beam with respect to the scanning plane
The scattered light generated from the convex member on the object is detected and the received light is detected.
It is characterized in that the convex amount of the convex member attached on the object is measured by using the output signal from the optical element . The convex amount measuring device according to the invention of claim 8 uses light from the light source means.
When the object is scanned by the scanning means using the beam, the optical beam
Scan line on the object and the light beam
Scan formed by the tangent line at the scan point on the object
Light receiving element in the space on the incident side of the light beam with respect to the plane
And when scanning the object with the light beam
Of the light beam from the scanning area of the object to the scanning plane
The light beam emitted into the space on the incident side enters the light receiving element.
A light-shielding device is provided to prevent the
The projection protruding into the space on the incident side of the light beam with respect to the inspection plane
The scattered light generated from the convex member on the object is detected, and the light receiving element is detected.
It is characterized in that the convex amount of the convex member attached on the object is measured by using the output signal from the child .

According to the surface condition inspection method of the present invention, the surface of the object is inspected by using any one of the above-mentioned constitutions (1-1), (1-2) and (1-3). Is characterized by. The convex amount inspection device of the present invention has the above-mentioned configuration (1-1),
It is characterized in that the protrusion amount (convex amount) of the convex member is measured using any one of (1-2) and (1-3).

[0012]

Embodiment 1 FIG. 1 is a schematic view of the essential portions of Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view of a main part of a part of FIG.

In the figure, 1 is a light source means, for example He-
It has an Ne laser and an optical system for condensing the light beam 1a emitted from it. Denoted at 2 is a deflecting means, which is composed of a rotating polygon mirror (polygon mirror), rotates at a constant speed around a rotation axis 2a, and deflects and reflects a light beam 1a from the light source means 1. Reference numeral 3 denotes a scanning optical system having an f-θ characteristic, which focuses the light beam from the polygon mirror 2. The deflecting means 2 and the scanning optical system 3 constitute one element of the scanning means. Reference numeral 4 denotes a folding mirror, which is a scanning optical system 3
Is reflected in a predetermined direction. Reference numeral 5 denotes an object to be measured, which has a cylindrical shape in this embodiment, and detects the presence or absence of a convex member (also referred to as a convex portion) such as dust or dust adhering to the surface 5b thereof. is doing. Object 5
Rotates about the rotating shaft 5a at a constant speed as indicated by an arrow.

Reference numeral 6 is a light receiving fiber, which uniformly receives and collects the scattered light scattered by the defects on the surface of the object 5. Reference numeral 7 denotes a photoelectric converter for converting the light collected by the light receiving fiber 6 into an electric signal, which is composed of, for example, a photomultiplier. A signal processing unit 8 detects the presence of a defect from the electric signal from the photoelectric converter 7. The light receiving fiber 6 and the photoelectric converter 7 form an element of the light receiving means 101. In the present embodiment, the light receiving element may be directly arranged at the position of the light receiving fiber 6.

In the present embodiment, the light beam 1a emitted from the light source means 1 is deflected by the scanning polygon mirror 2, condensed by the scanning optical system 3, and changed by the folding mirror 4 so as to move toward a predetermined position. The surface 5b of the cylindrical object 5
Scan in the longitudinal direction. 5c shows the scanning line at this time. The object 5 rotates slowly with respect to the scanning speed of the light beam 1a, so that the entire surface 5b is scanned by the light beam 1a.

In this embodiment, the object 5 is made of metal and is opaque, so that the light beam 1a which hits the object 5 is reflected or scattered. At that time, a region where the scanning state of the light beam on the surface of the object 5 is visible (on the incident side of the light beam above the scanning plane formed by the scanning line 5c of FIG. 1 and the tangent line 5d of the incident point of the light beam 1a) The scattered light on the surface 5b reaches the area S1), but the area is a shadow of the object 5 itself (the area S2 which is a space area below the scanning plane of FIG. 1 opposite to the incident side of the light beam). ) Is not reached by the scattered light on the surface 5b. On the other hand, if the surface 5b of the object 5 has a defective portion such as a convex member locally, if the light beam 1a scans just there, the light beam 1a is scattered at a high position of the convex member. , The scattered light on the convex member is the area S2 in FIG.
Reach to. Then, the higher the height of the convex member, the wider the angle at which the scattered light reaches in the area S2 direction.

Therefore, in this embodiment, the light receiving fiber 6 or the light receiving element (not shown) is arranged in the region S2 of FIG. This is the characteristic configuration of the present invention. as a result,
When the object is a normal non-defective part, the scattered light from the part is not received by the light receiving means 101 at all. And surface 5
When there is a convex portion on b, only the scattered light from the convex portion is detected by the light receiving means 101. Then, the scattered light at this time is converted into an electric signal by the photoelectric converter 7. If there is a defect such as a convex portion, a pulsed detection signal is obtained at a position corresponding to it. The presence / absence of a convex member on the surface 5b of the object 5 is detected by performing a determination process on this by the signal processing unit 8.

Further, the larger the angle of the light receiving fiber 6 is from the scanning plane including the boundary line 5d between the area S1 and the area S2 in FIG. 1, the larger the convex portion is detected. Therefore, the amount of separation at this time is adjusted to quantitatively determine the amount of protrusion of the convex portion. Next, the reason for this will be described with reference to FIG.

The center of the object 5 (corresponding to the center of rotation 5a) is O, the radius is r, and the point on the surface 5b of which the light beam 1a is scanning is A. Then, the height of the convex portion is d, and the point convexed by the height d is B. The height d is smaller than the radius r and is d << r, but is shown large in the figure for the sake of explanation. The tangent line passing through the point A is AD, and the tangent line passing through the point B is BE. The plane formed by the scanning line 5c and the tangent line AD is the scanning plane. Tangent line B
E is in contact with the circle at point C, and the angle AOC is θ.

On the surface 5b of the non-defective part, the light beam 1a has a point A.
In order to spot-illuminate the position of
It only reaches the range of 1. The boundary line of whether the scattered light reaches or does not reach is a tangent line AD passing through the point A, assuming that the spot diameter of the light beam is ideally small. On the other hand, the surface 5b
Assuming that the light beam scans a point B that has a convex portion on its surface and is higher than the surface 5b by a height d, the scattered light at the point B is extended to the direction E, which is a marginal angle blocked by the circumference. It will arrive. Since this object 5 itself acts as a light shield, this angle is hardly affected by the mounting position deviation and eccentricity.

The angle θ and the radius r of the object 5 at that time are:
The relationship with the height d of the convex portion is cos θ = r / (r + d). That is, when the size of the object 5 and the height d of the convex portion as a defect to be detected are determined, the angle at which the light receiving fiber should be arranged is determined. Thereby, the height of the convex portion is quantified and determined. On the contrary, move the angle of light reception, measure at what angle the signal from the convex part can be detected, and calculate from the above formula to measure the height of the detected convex part. is doing.

As described above, according to this embodiment, the scattered light from the non-defective portion is not received at all, and only the scattered light from the convex member is received so that the presence or absence of the convex portion can be detected with high sensitivity. There is. In addition, even if the scattered light in the non-defective part has a large variation due to the surface roughness of the target object or pear texture treatment, the influence is eliminated, and the presence or absence of the convex part is detected with a high S / N. . Since the object 5 itself is used for light shielding, even if the cylindrical object has eccentricity, the deviation of the angle that blocks scattered light is small, and thus the error in detecting the height of the convex portion is small. Further, if the height of the convex portion of the defect to be detected is determined with respect to the object 5, the placement of the light receiving fiber 6 is determined, and therefore the height of the convex portion can be quantified to determine the presence or absence of the convex portion. . Further, the height d of the convex portion is obtained from the above equation by moving the angle of the light receiving fiber 6 and obtaining the angle at which the light receiving signal starts to appear.

FIG. 3 is a schematic view of the essential portions of Embodiment 2 of the present invention, and FIG. 4 is a sectional view of the essential portions of FIG.

In this embodiment, a flexible sheet-like transparent film is used as the object 5 for detecting the surface state, and the transparent film is applied to the guide roller 9 which is a cylindrical rotating object by the arrow 9.
It is different from the first embodiment in that it is moved in contact with the a direction, and the knife edge 10 is used as a light blocking means for blocking the scattered light from the non-defective part of the target object 5, and other configurations are the same. Is. The light shielding means 10 is arranged in a space opposite to the light beam incident side with respect to the scanning plane.

In this embodiment, the light beam 1a scans the surface 5b on the object 5 made of a transparent film. The scanning position at that time is a position where the object 5 is placed on the guide roller 9, and is a portion which is curved following the surface of the guide roller 9. The object 5 is sent with the rotation of the guide roller 9 to scan the object 5 with the light beam 1a continuously as shown by the scanning line 5c.

In this embodiment, since the object 5 is transparent, the object itself does not have the effect of blocking light as described in the first embodiment. Therefore, the knife edge 10 is set to the target 5
This knife edge 10 blocks the scattered light from the non-defective part of the object 5 by arranging it at a position close to the scanning point of the light beam. The region S1 is a region where the scattered light from the non-defective portion is not blocked by the knife edge 10, and the region S2 is a region where it is blocked.

On the other hand, if the surface 5b of the object 5 has a convex portion, the light is scattered at a high position, and the scattered light reaches the area S2. The higher the height of the protrusion, the more the area S
It will spread widely to 2 people.

Therefore, the light receiving fiber 6 is arranged in the region S2. This is the characteristic configuration of this embodiment. In this embodiment, the scattered light from the non-defective portion is not received at all, and only the scattered light at the convex portion is received by the light receiving means 101. This scattered light is converted into an electric signal by the photoelectric converter 7. If there is a convex portion, a pulsed detection signal can be obtained at a position corresponding to the convex portion. The signal processing unit 8 processes this signal to detect a defect on the transparent film 5.

Next, the characteristic part of this embodiment will be described with reference to FIG. The object 5 having the thickness t is hung on the guide roller 9 and bent along the surface of the guide roller 9 as shown in FIG. The light beam 1a irradiates the point A of the bent portion in a spot shape. Scattered light at this non-defective part is knife edge 1
By 0, light below the point P, that is, below the scanning plane is blocked and reaches the angle of the region S1 in the figure, but does not reach the angle of the region S2. The boundary line 5d is the line segment AD.
On the other hand, if the surface 5b of the object 5 has a convex portion with a height d, the scattered light at the point B of the convex portion is scattered at a high position, so that the line segment E direction is further extended to the angle θ direction. reach. The angle difference θ at this time is determined by the position P of the knife edge 10, the operating position A of the light beam 1a, and the height d of the convex portion.

Here, the relation OA is the simplest, the angle OA
An example is shown when P = 90 degrees, but in other cases, the relational expression is slightly complicated and there is no essential difference. If the distance between the operating position A of the light beam 1a and the position P of the knife edge 10 is L, then the angle BAP = 90 degrees, so tan θ = d / L. That is, as the height d of the convex portion increases, the scattered light there reaches a larger angle to the region S2. Further, the closer the knife edge 10 is to the scanning position of the light beam 1a, the larger the scattered light reaches. From the above, by arranging the light receiving fiber 6 at the angle of this region S2, only the scattered light from the convex portion is captured.

As described above, according to this embodiment, the scattered light from the non-defective portion is not received at all, and only the scattered light from the convex portion is received, so that the presence or absence of the convex portion can be detected with high sensitivity. is doing. Even if the scattered light in the non-defective part has a large variation due to the roughness of the surface of the target object or pear texture processing, the effect is reduced, and the convex part is detected with a stable high S / N ratio. There is. Further, according to the present embodiment, if the convex amount (height) of the convex portion to be detected is determined, the knife edge 1
0 and the arrangement of the light-receiving fiber 6 can be determined, whereby the height of the convex portion can be quantified and the presence or absence of the convex portion can be determined.

FIG. 5 is a schematic view of the essential portions of Embodiment 3 of the present invention, and FIG. 6 is a sectional view of the essential portions of FIG.

In this embodiment, a flat glass substrate is used as the object 5 whose surface state is to be detected, an automatic stage 11 is used to move the object 5, and a non-defective product of the object 5 is used. The present embodiment is different from the first embodiment in that a knife edge 10 is used as a light blocking means for blocking the scattered light from the portion, and the other configurations are the same. still,
The light blocking means 10 is arranged in the space on the light beam incident side of the scanning plane.

In this embodiment, the surface 5b of the object 5 made of a glass substrate is scanned with the light beam 1a. Then, the automatic stage 11 is slowly moved with respect to the scanning speed of the light beam 1a to scan the entire surface of the object 5 with the light beam. Since the object 5 is flat in this embodiment, the knife edge 10 is arranged in the space above the object 5. As a result, the knife edge 10 blocks the scattered light from the non-defective part. A region where the scattered light from the non-defective portion is not blocked by the knife edge 10 is a region S1 in FIG. 5, and a blocked angle is a region S2 in FIG. On the other hand, if the surface 5b of the object 5 has a convex portion, the light beam is scattered at a position where the convex portion is high, and thus the scattered light reaches the area S2. As the height of the convex portion is higher, the area S2 is more widely spread and reaches the area S2.

Therefore, the light receiving fiber 6 is arranged in the region S2. This is the characteristic configuration of this embodiment. As a result, the scattered light from the non-defective portion is not received at all, and only the scattered light at the convex portion is received by the light receiving means 101. The scattered light at this time is converted into an electric signal by the photoelectric converter 7. If there is a convex portion, a pulsed detection signal can be obtained at a position corresponding to the convex portion. This signal is sent to the signal processing unit 8
The presence / absence of a convex portion on the glass substrate is detected by performing the processing described in 1.

Next, the characteristic part of this embodiment will be described with reference to FIG. The spot A of the object 5 is irradiated with the light beam 1a as a spot. The scattered light from the non-defective part is the knife edge 10
As a result, the light below the point P is blocked and reaches the angle of the area S1 in the figure, but does not reach the angle of the area S2. The boundary line 5d is the line segment AD.

On the other hand, when the surface 5b of the object 5 has a convex portion with a height d, the scattered light from the point B of the convex portion has a high scattering position, and therefore, the angle E direction of the line segment E direction is further extended. reach.
The angle difference θ at this time is determined by the position P of the knife edge 10, the scanning position A of the light beam 1a, and the height d of the convex portion. If the distance between the scanning position A of the light beam 1a and the position P of the knife edge 10 is L, and the height of the knife edge point P from the point A is h, then θ = arctan L / (hd)- arcta
n L / h. That is, as the height d of the convex portion increases, the scattered light there reaches a larger angle to the region S2.

By arranging the light receiving fiber 6 in this region S2, only the scattered light from the convex portion is captured.

As described above, according to this embodiment, the scattered light from the non-defective portion is not received at all, and only the scattered light from the convex portion is received, and the presence or absence of the convex portion is detected with high sensitivity. There is. In addition, the unevenness of the scattered light in the non-defective part is large due to the roughness of the surface of the object or the pear treatment, and even if the scattered light amount is not uniform, the effect is reduced and the S / S ratio is high.
The presence / absence of a convex portion can be detected by N.

If the height of the convex portion to be detected is determined,
The arrangement of the knife edge 10 and the light receiving fiber 6 can be determined, and the height of the convex portion can be quantified to determine the presence or absence of the convex portion.

[0041]

As described above, according to the present invention, the surface of an object is scanned with a light beam and scattered light generated from a convex member as a defective portion such as dust or dust adhering to the surface is scattered. By using the signal obtained from the light receiving element properly arranged in the space, the surface condition inspection device which can detect the convex member accurately without being affected by the roughness and non-uniformity of the surface of the object is achieved. can do.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the essential parts of Embodiment 1 of the present invention.

FIG. 3 is a schematic view of the essential portions of Embodiment 2 of the present invention.

FIG. 4 is a sectional view of an essential part of a second embodiment of the present invention.

FIG. 5 is a schematic view of the essential portions of Embodiment 3 of the present invention.

FIG. 6 is a cross-sectional view of the essential parts of Embodiment 3 of the present invention.

[Explanation of symbols]

1 light source means 2 deflection means 3 Scanning optical system 4 folding mirror 5 objects 6 Light receiving fiber 7 Photoelectric converter 8 Signal processing circuit 9 Guide roller 10 Shading means 101 light receiving means

Front page continued (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01N 21/84-21/958 G01B 11/00-11/30

Claims (8)

(57) [Claims] 1. When a scanning means scans an object with a light beam from a light source means, a scanning line on the object by the light beam and a tangent line at a scanning point on the object by the light beam. A light receiving element is provided in the space opposite to the incident side of the light beam with respect to the scanning plane formed by, and when the light beam is incident on the object, A convex member on the object which is provided with a light shielding means for shielding a light beam emitted into the space opposite to the incident side, and which is projected by the light receiving element into the space on the incident side of the light beam with respect to the scanning plane. A surface condition inspection device, which detects scattered light generated from the light receiving device and inspects a surface condition on the object using an output signal from the light receiving element. 2. The surface condition inspection apparatus according to claim 1 , wherein the light shielding means is a knife edge parallel to the scanning line. 3. When a scanning means scans an object with a light beam from a light source means, a scanning line on the object by the light beam and a tangent line at a scanning point on the object by the light beam. A light receiving element is provided in the space on the incident side of the light beam with respect to the scanning plane formed by, and when scanning the object with the light beam, The scanning for preventing the light beam emitted into the space on the incident side of the light beam from entering the light receiving element
A light-shielding means composed of knife edges parallel to the line is provided, and the light receiving element detects scattered light generated from a convex member on the object projecting into the space on the incident side of the light beam with respect to the scanning plane, A surface condition inspection apparatus, which inspects a surface condition on an object using an output signal from a light receiving element. 4. The surface condition inspection apparatus according to claim 1, wherein the object is a cylindrical object, a sheet-shaped transparent object, or a plate-shaped transparent object. 5. A surface condition inspecting method for inspecting a surface condition on an object using the surface condition inspecting apparatus according to any one of claims 1 to 4 . 6. A convexity characterized by measuring the convexity of a convex member adhering to the object using the surface condition inspection apparatus according to claim 1. Quantity measuring device. 7. A scanning device using a light beam from a light source means.
On the object by the light beam when scanning the object in steps
Scanning line at and the scanning point on the object by the light beam
To the scanning plane formed by the tangent line at
Provide a light receiving element in the space on the side opposite to the incident side of the
The light element causes the sky on the incident side of the light beam with respect to the scanning plane
The scattered light generated from the convex member on the target that protrudes in the space
The object detected by using the output signal from the light receiving element
A convex amount measuring device characterized in that the convex amount of a convex member attached to the upper side is measured. 8. A scanning device using a light beam from a light source means.
On the object by the light beam when scanning the object in steps
Scanning line at and the scanning point on the object by the light beam
To the scanning plane formed by the tangent line at
A light receiving element is provided in the space on the incident side of the beam and
The scanning area of the object when scanning
Exits into the space on the incident side of the light beam with respect to the scanning plane
Light-shielding hand for preventing incident light flux from entering the light receiving element
A step is provided, and the optical beam is provided more than the scanning plane by the light receiving element.
From the convex member on the object protruding into the space on the incident side of the frame
The generated scattered light is detected and the output signal from the photo detector is used.
The convex amount measuring device is characterized in that the convex amount of the convex member attached to the object is measured.