JPH09210916A - Foreign matter inspection device and foreign matter inspection method - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: It is impossible to inspect depending on a two-dimensional shape of a region to be inspected on a mask surface. A mask includes the mask based on a two-dimensional shape of a region to be inspected on the surface of the mask and a two-dimensional shape of an actually inspectable region which is determined by physical restrictions due to the presence of a protective thin film. Rotation means is provided which rotates in a plane to change the relative positional relationship of the mask with respect to the scanning direction of the light beam. It is possible to obtain a foreign matter inspection apparatus capable of inspecting a mask for foreign matter at an optimum position according to a required inspection region and the shape of a protective thin film and further shortening the inspection time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foreign matter inspection apparatus and method, and can be applied to, for example, a foreign matter inspection apparatus and method for inspecting the presence or absence of foreign matter on a mask surface.

[0002]

2. Description of the Related Art In a semiconductor exposure process, if exposure is performed with foreign matter such as dust adhered to the surface of a mask, reticle, or the like, a wafer may be defective, and therefore, a foreign matter inspection apparatus having the configuration shown in FIG. 1 is used to inspect for the presence of foreign matter before exposure. By the way,
Shows an example of the reticle 2 in which a protective thin film (hereinafter referred to as pellicle) 3 is mounted on the surface of the reticle 2 to be inspected. Here, the pellicle 3 is for reducing the frequency of foreign matter directly adhering to the surface of the reticle 2, and the thin film 3
It is composed of A and a frame 3B. Incidentally, the pellicle 3 is attached to the reticle 2 via an adhesive (not shown).

When the reticle 2 thus protected by the pellicle 3 is placed on the mounting table 4, the mounting table 4 on which the reticle 2 is mounted is driven by the drive unit 5. The presence or absence of foreign matter is inspected by moving in the Y direction and scanning the surface of the reticle 2 with a laser beam that is scanned in a direction orthogonal to the moving direction. The Y of the mounting table 4
The amount of movement with respect to the direction is measured by a length measuring device 6 such as a linear encoder, and the movement speed is controlled to be constant based on the measurement result. A scanning beam L2 for scanning the surface of the reticle 2 is obtained by deflecting a light beam L1 emitted from a light source 7 such as a laser by a light deflection scanner 8 such as a galvanometer mirror scanner or a polygon mirror scanner to scan a scanning lens. Reticle 2 through 9
It is obtained by focusing on the surface of. At this time, the locus of the scanning beam L2 on the reticle 2 is called a scanning line 10, which coincides with the X direction in this configuration example.

In the foreign matter inspection apparatus 1, scattered light L3 from the foreign matter 11 generated when the scanning beam L2 scans the foreign matter 11 on the scanning line 10 is provided with two light receiving lenses arranged around the mounting table 4. Photoelectric detectors 14, 1 via 12, 13
The presence or absence of the foreign matter 11 is inspected by causing the foreign matter 11 to enter. The photoelectric detectors 14 and 15 are photomultipliers or the like. Thus, the foreign matter inspection device 1 specifies the position of the foreign matter 11 in the Y direction by the length measurement signal of the length measuring device 6 at the time when the two photoelectric detectors 14 and 15 receive light, and the light at that time is specified. The position of the foreign substance 11 in the X direction is specified by a position signal (electrical signal corresponding to the deflection angle of the mirror) of the polarization scanner 8 or the like.

By the way, the circuit pattern 16 naturally exists on the reticle 2, and the diffracted light L4 is also generated from this circuit pattern 16. Therefore, the foreign matter inspection device 1 utilizes the difference in characteristics of the diffracted light L4 and the scattered light L3 to detect only the scattered light L3 from the reflected light. That is, the scattered light L3 reflected by the foreign matter 11
Takes advantage of the fact that the diffracted light L4 reflected by the circuit pattern 16 has directivity while the scattered light is isotropically generated in all directions.

When both of the two photoelectric detectors receive light above a certain level, the foreign matter inspection apparatus 1 determines that it is the scattered light L3 from the foreign matter 11, and only one of the photoelectric detectors exceeds a certain level. If the light is received, it is possible to detect only the foreign matter 11 on the reticle 2 by determining that it is the diffracted light L4 from the circuit pattern 16. Thus, the ability to detect the foreign matter 11 depends on how much the foreign matter can be discriminated from the pattern.

Therefore, in the actual foreign matter inspection apparatus 1, the incident angle of the scanning beam L2 (the angle formed by the scanning beam L2 and the normal line of the reticle 2) so that the diffracted light L4 reflected by the circuit pattern 16 does not come as much as possible. And the photoelectric detectors 14 and 15 for receiving the light are preferably arranged. Specifically, the incident angle is increased (that is, the scanning beam L2 is almost horizontal with respect to the reticle 2), and the photoelectric detectors 14 and 15 are obliquely arranged toward the side on which the scanning beam L2 is incident. It is preferable. Because the diffracted light L4 generated by the circuit pattern 16 of the reticle 2 is strong on the specular reflection side and the transmission side having a low order, the diffracted light L4 can be received by increasing the incident angle from the rear (incident side). This is because only the higher order light of L4 is received.

[0008]

However, in the foreign matter inspection apparatus 1 having this structure, the reflected light is blocked because the area 2A or the frame 3B which is in the shadow of the frame 3B and cannot be illuminated by the scanning beam L2 and the frame 3B block the reflected light. There is a problem that areas 2B and 2C that cannot reach the photoelectric detectors 14 and 15 are formed. Furthermore, in the foreign matter inspection apparatus 1, the scanning beam L2
Is multi-reflected on the front and back surfaces of the reticle 2 and the surface of the thin film 3A, and hits the edge face of the reticle 2 and the frame 3B to generate light (hereinafter referred to as back light) that interferes with foreign matter detection, and cannot be inspected. There is a problem that the region 2D is generated near the inside of the frame 3B and limits the inspection region.

The present invention has been made in consideration of the above points, and it is an object of the present invention to propose a foreign matter inspection apparatus and method capable of ensuring the widest possible inspection area and shortening the inspection time. .

[0010]

In order to solve such a problem, according to the present invention, it is possible to actually carry out the inspection which is determined by the two-dimensional shape of the region to be inspected on the mask surface and the physical constraint due to the existence of the protective thin film. Rotating means for rotating the mask in a plane including the mask based on the two-dimensional shape of the region and changing the relative positional relationship of the mask with respect to the scanning direction of the light beam is provided. As a result, the mask can be inspected for foreign matter at an optimum position according to the required inspection region and the shape of the protective thin film, and the inspection time can be shortened.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

(1) Foreign Particle Inspection Method Generally, the inspection time required for the foreign particle inspection is determined by the length of the inspection area in the moving direction (Y direction in FIG. 10) and the feed speed of the reticle 2 by the drive unit 5. be able to. Therefore, the length of the inspection area in the Y direction is 100 mm.
If the feed rate is 1 [mm / sec], the inspection time will be 100 [mm] ÷ 1 [mm / sec] = 100 [sec].
Of these, the feed rate is determined by the scanning period of the optical deflection scanner 8 and the light spot diameter of the scanning beam L2 on the reticle 2. The smaller the light spot diameter, the more unstable the feed rate becomes. It is effective to increase the inspection time in order to shorten the inspection time.

However, since the optical spot diameter has a unique value for each device, it is considered that the inspection time depends on the scanning cycle. However, with respect to this scanning cycle as well, if the width of the inspection area of the reticle 2 in the X direction (scanning direction of the scanning beam L2) is small, the scanning cycle will be small and the feed speed will be fast, but there is a practical limit. The inspection time could not be shortened. This is because even if the deflection angle of the Galvano mirror scanner or the polygon mirror scanner used as the optical deflection scanner 8 is reduced, the scanning cycle cannot be shortened much. From the above, it can be seen that the scanning time depends not on the width of the inspection region in the X direction but on the length in the Y direction and is proportional to the length in the Y direction. That is, if the reticle 2 is rotated and installed in such a direction that the length in the Y direction is shortened, the inspection time can be shortened.

FIG. 1 shows the situation. However, in the drawing of FIG. 1, the X direction and the Y direction correspond to the X direction and the Y direction shown in FIG. 10, respectively. First, when it is desired to inspect the inspection area AR1 (indicated by diagonal lines in the figure) of the reticle 2 on which the rectangular frame 3B is mounted as shown in FIG. 1A, as shown in FIG. 1 rather than arranging so that the longitudinal direction is parallel to the Y direction.
As shown in (B), it is possible to shorten the length of the inspection area AR1 in the Y direction by arranging the longitudinal direction in parallel with the X direction. That is, the inspection time can be shortened by arranging as shown in FIG.

The above is the method of arranging the reticle 2 when the inspection time is prioritized, but the above-mentioned arrangement is not always a good idea when it is desired to prioritize securing of the inspection area that can be inspected over the inspection time. An example of such a case is shown in FIG. For example, as shown in FIG.
Although R1 is a hatched area, inspectable area A
When R2 is a region surrounded by a broken line, regions AR11 and AR12 outside the broken line in the inspection region AR1 are regions that cannot be inspected.

However, as shown in FIG. 2B, if the reticle 2 is rotated 90 [°] to change its direction, the entire inspection area AR1 can be included inside the inspectable area AR2 shown by the broken line. In this case, the arrangement shown in FIG. 2B has a longer length of the inspection area AR1 in the Y direction than the arrangement shown in FIG.
The entire surface of the inspection area AR1 can be inspected. In this way, the orientation in which the reticle 2 should be arranged is different depending on whether the inspection time is prioritized or the area where the inspection is possible is prioritized. In either arrangement, the inspection area AR1 is the inspectable area AR2. If not included, the foreign matter inspection method described below is required. This foreign matter inspection method will be described with reference to FIGS.

First, when the reticle 2 is arranged as shown in FIG. 3, the inspection area AR1 which is an area to be inspected is located at the position Δx = 6 [mm] and Δy = 9 [mm] from the inside of the frame 3B. , The inspectable area AR2 is frame 3
Since it is located at ΔX = 5 [mm] and ΔY = 10 [mm] from the inside of B, the width of each end in the Y direction is 1 [mm].
The area portion of (= ΔY−Δy) becomes an uninspectable area. In this case, as shown in FIG.
Although it may be considered that the inspection area AR2 is rotated by [°] and arranged, the inspection area AR2 cannot include the inspection area AR1.

Therefore, in the foreign matter inspection method according to the present application, FIG.
As shown in FIG. 7, the entire surface of the inspection area AR1 is included in the inspectable area AR2 by rotating the reticle 2 in the clockwise direction by an angle θ so that each side of the reticle 2 is oblique to the scanning beam L2. To In the case of this example, the angle θ is θ = tan ⁻¹ (ΔX / ΔY) = 26.6 [°]. At this time, the inspectable area AR from the inside of the frame 3
The distance to 2 (ΔX ′, ΔY ′) is ΔX ′ = ΔX cos θ
= 4.47 [mm], ΔY ′ = ΔY cos θ = 8.94 [mm], and Δx = 6 [mm] and Δy = 9 [m] giving the distance (Δx, Δy) from the inside of the frame 3 to the inspection area AR1.
m] and the inspection area AR1 is included in the inspectable area AR2.

However, since the inspection time is determined by the length L in the Y direction in FIG. 5, assuming that the width of the inspection area AR1 is X and Y, the inspection time is the length L = X sin θ + Y cos θ = 0.45X +
It takes 0.89Y divided by the scanning cycle. At this time, since the length L is longer than the short side of the inspection area AR1 and shorter than the long side, the inspection time is longer than when the short side is arranged in the Y direction, and the long side is in the X direction. It takes less time than when placed in. ΔX
And ΔY are values that are peculiar to the foreign substance inspection apparatus that are determined by the incident angle of the scanning beam L2, the arrangement of the photoelectric detector 8, and the like.

(2) First Embodiment FIG. 6, in which parts corresponding to those in FIG. 10 are designated by the same reference numerals, shows the overall structure of the foreign matter inspection device 21. This foreign matter inspection device 2
1 has a rotating mechanism for rotating the reticle 2 by an angle θ in the XY plane and changing its direction, as described in the previous section. That is, the foreign matter inspection device 21
The rotary table 22 is configured to rotate in the XY plane while the reticle 2 is placed on the reticle 2, and the drive unit 23 that drives the rotary table 22.

Here, the disk-shaped rotary table 22 and the drive unit 23 are each a plate-shaped mounting table 4 which is movable in the Y direction.
They are mounted on the top of the drive unit 23, and are connected to each other by meshing the threads formed on the shaft 23A of the drive unit 23 with the thread grooves. Incidentally, the screw groove is formed along the circumference of the rotary table 22, and the screw groove is fed in the axial direction by a movement amount corresponding to the rotation amount of the shaft 23A, so that a driving force for rotating the rotary table 22 acts. It is made possible. The rotation amount of the rotary table 22 and the rotation number of the shaft 23A commensurate with the rotation amount are calculated by the rotation amount determining device 24.

With the above arrangement, the foreign matter inspection device 21 executes the foreign matter inspection in the following procedure. First, the foreign matter inspection device 21
Starts the process of determining the optimum placement of the reticle 2 for the foreign matter inspection prior to the execution of the foreign matter inspection. At this time, the foreign substance inspection device 21 preferentially searches for an arrangement capable of inspecting the entire surface of the inspection area AR1, and when the position where the entire surface can be inspected is known, searches for a direction in which the inspection time can be shortened as much as possible.

At this time, the foreign matter inspection device 21 uses the rotation amount determination device 24. The rotation amount determination device 24 has a rotation angle of 0 [°] based on various conditions input from the input device 25 (that is, the size of the frame 3B, the incident angle of the scanning beam L2, the arrangement of the photoelectric detectors 14 and 15). Of the inspectable area AR2 in the case from the inner wall of the frame (ΔX, ΔY)
Further, the distance (Δx, Δy) from the inner wall of the frame of the inspection area AR1 is input from the input device 25 and held.

When the initial condition setting work is completed in this way, the rotation amount determining device 24 proceeds to work for determining the rotation amount of the rotary table 22 according to the procedure shown in FIG. The rotation amount determining device 24 determines the distance (Δx, Δy) from the inside of the frame that gives the inspection area AR1 and the distance (ΔX, Δ) from the inside of the frame that gives the inspectable area AR2 in step SP2.
Compare with Y). At this time, when the value of the inspection area AR1 is larger for both the distance in the X direction and the distance in the Y direction, the inspection area A is set in the current orientation of the reticle 2.
It is determined that the entire R1 is included in the inspectable area AR2,
If a positive result is obtained, the operation proceeds to step SP3.

This step SP3 is a desired inspection area AR.
This is a determination step necessary to determine the direction in which the inspection time is shortened as much as possible under the condition that the entire surface of 1 can be inspected. That is, the rotation amount determination device 24 uses Δx, ΔY, Δ
Compare y with ΔX. At this time, if Δx and Δy are larger than ΔX and ΔY, set the reticle 2 to
The inspection area AR1 is inspectable area A even if it is rotated by 90 [°].
Since it is determined to be included in R2, an affirmative result is obtained and the operation proceeds to step SP4.

Thus, even if the rotation angle is 0 [°], it is 90
Even if it is [°], the inspection area AR1 is the inspectable area AR2.
, The rotation amount determination device 24 determines the short side of the two sides X and Y of the inspection area AR1 in the step SP4, and the short side is the driving direction of the reticle 2 (that is, the Y direction). Then, the process ends. On the other hand, if a negative result is obtained in step SP3, it is understood that the inspection area AR1 extends out of the inspectable area AR2 when the reticle 2 is rotated by 90 [°] from the current orientation, and therefore the circuit determination device 24 concerned. The position of the reticle 2 should be 0 in step SP6.
It is set to be [°].

On the other hand, when a negative result is obtained in step SP2 and it is found that the inspection area AR1 is not included in the inspectable area AR2 in the current orientation (that is, 0 [°]), the rotation is performed. The amount determining device 24 proceeds to step SP7 and proceeds to a process of determining whether or not the inspection area AR1 is included in the inspectable area AR2 when the orientation of the reticle 2 is rotated by 90 [°]. If a positive result is obtained at this time, the inspection area AR1 can be included in the inspectable area AR2 by rotating the reticle 2 by 90 [°]. Therefore, this direction is set as the direction of the reticle 2 in step SP8. .

However, a negative result is also obtained in step SP7, and the rotation angle of the rectangular inspection area AR1 is set to 0.
If it is found that the inspection area AR1 cannot be included in the inspectable area AR2 even if it is set to [°] or 90 [°], the rotation amount determination device 24 expands the inspectable area AR2 to cover the entire inspection area AR1. Alternatively, the angle θ for rotating the reticle 2 is set to tan ⁻¹ (ΔX / ΔY) in step SP9 so that most of it is included.

When the orientation of the reticle 2 is determined in this way, the rotation amount determining device 24 gives a drive signal to the drive unit 23 to drive the shaft 23A so that the orientation of the reticle 2 becomes the determined angle θ. Then, the rotary table 22 is rotated to complete the positioning work of the rotary table 22. After that, the foreign matter inspection device 21 drives the mounting table 4 in the Y direction by the drive unit 5 while scanning the surface of the reticle 2 with the scanning beam L2, and executes the necessary inspection of the inspection area AR1.

According to the above construction, the reticle 2 is placed on the rotary table 22 which can freely rotate in the XY plane, so that the rotary table 22 can be mounted on the rotary table 22 because of the arrangement of the frame 3B of the pellicle 3 and various optical systems. Immediately after being placed, the inspection area AR1 of the reticle 2 is the inspectable area AR.
Even if it is not included in 2, the direction can be changed so that it is included in the inspectable area AR2. As a result, it is possible to realize a foreign matter inspection device having a wide inspection range. When the inspection area AR1 of the reticle 2 is included in the inspectable area AR2, the orientation of the reticle 2 can be changed so that the inspection time can be shortened.

(3) Second Embodiment A second embodiment of the foreign matter inspection apparatus according to the present invention is shown in FIG. 8 in which parts corresponding to those in FIG. The foreign substance inspection device 31 shown in FIG. 8 has the same configuration as the foreign substance inspection device 21 shown in FIG. 6 except that the mechanism of the rotating means for rotating the reticle 2 is different.

That is, the foreign matter inspection device 31 does not mount a rotating means for rotating the reticle 2 on the upper surface of the mounting table 4 on which the reticle 2 is mounted, but rotates the reticle 2 together with the mounting table 4. ing. For this reason, a shaft is fixed to the base portion of the mounting table 4, and the mounting unit 4 can be rotated in the XY plane by driving the shaft by the driving unit 32. The drive unit 32 is attached to the X-direction drive unit 33, and the X-direction drive unit 33 is attached to the Y-direction drive unit 34. Therefore, this foreign matter inspection device 3
Reference numeral 1 denotes a reticle 2 which can be moved in parallel in the X direction and the Y direction, and can be rotated in the XY plane. Otherwise, the operation is similar to that of the first embodiment.

According to the above construction, the reticle 2 can be moved in parallel and rotationally on the XY plane while being placed on the mounting table 4 having a bifurcated shape. In view of the arrangement of the frame 3B of the pellicle 3 and various optical systems, the inspection area AR1 of the reticle 2 can be surely inspected even when the inspection area AR1 is not included in the inspectable area AR2 immediately after being placed on the rotary table 22. The orientation can be changed so that it can be included in the area AR2. As a result, it is possible to realize a foreign matter inspection device having a wide inspection range. Also, the inspection area AR of the reticle 2
When 1 is included in the inspectable area AR2, the orientation of the reticle 2 can be changed so that the inspection time is shorter.

(4) Third Embodiment FIG. 9 in which parts corresponding to those in FIG. 6 are assigned the same reference numerals shows a third embodiment of the foreign matter inspection apparatus according to the present invention. The foreign substance inspection device 41 shown in FIG. 9 differs from the foreign substance inspection device 21 shown in FIG. 6 in that the mounting table 4 and the XY for moving the reticle 2 in parallel in the Y direction.
It is characterized in that the rotating means for rotating in the plane are separately configured.

That is, the foreign substance inspection device 41 has only a moving function in the Y direction as the mounting tables 4A and 4B on which the reticle 2 is mounted, and the rotation in the XY plane is the mounting tables 4A and 4B.
The rotation unit 42 provided above B in the Z direction is in charge. The rotating portion 42 is configured to be movable in the Z direction by a driving portion (not shown), and the claw 4 attached to the lower surface of the rotating portion 42.
After the reticle 2 is lifted by 2A, the driving section 43 changes the direction of the reticle 2. After the orientation is changed by the rotation, the rotating unit 42 is lowered again by the driving unit shown in the figure, and the operation of placing the reticle 2 on the placing tables 4A and 4B is repeated. Otherwise, the operation is similar to that of the first embodiment.

According to the above-described structure, the reticle 2 can be rotationally moved on the XY plane by using the rotating unit 42, so that the rotary tables 4A and 4B can be moved to the rotary tables 4A and 4B because of the arrangement of the frame 3B of the pellicle 3 and various optical systems. Even when the inspection area AR1 of the reticle 2 is not included in the inspectable area AR2 in the orientation immediately after being placed, the orientation can be changed to include it in the inspectable area AR2. As a result, it is possible to realize a foreign matter inspection device having a wide inspection range. When the inspection area AR1 of the reticle 2 is included in the inspectable area AR2, the orientation of the reticle 2 can be changed so that the inspection time can be shortened.

(5) Other Embodiments In the above-described embodiments, the case where the rotary table 22 has a disk shape is described, but the present invention is not limited to this, and the shape thereof may be circular such as elliptical. Not exclusively.
Further, in the above-described embodiment, the rotating unit 42 is mounted on the mounting table 4.
Although the case where the reticle 2 placed on the A and 4B is used only for changing the direction has been described, the present invention is not limited to this, and also serves as a transporting unit that transports the reticle 2 to and from the reticle stock portion. It can also be applied in cases.

That is, the rotating unit 42 is
It also serves as a Z-direction drive mechanism for receiving onto the stage 4A, 4B and an X- or Y-direction drive mechanism for taking out the reticle from a reticle stock portion (not shown). As a result, the rotating unit 42 takes out the reticle from the reticle stock unit and then follows the reticle orientation determination processing procedure.
Aim the reticle in the specified direction and place it on the stage. After the foreign matter inspection is performed, the rotating unit 42 performs the reverse operation to return the reticle to the reticle stock unit. Needless to say, the X- or Y-direction drive mechanism may be a separate transport mechanism.

[0039]

As described above, according to the present invention, the mask is rotated in the plane including the mask, and the rotation means for changing the relative positional relationship of the mask with respect to the scanning direction of the light beam is provided. Thus, it is possible to obtain a foreign matter inspection apparatus capable of inspecting a mask for foreign matter at an optimum position according to a required inspection area and a shape of a protective thin film and further shortening the inspection time.

[Brief description of drawings]

FIG. 1 is a schematic diagram used to explain a mask layout that realizes a reduction in inspection time.

FIG. 2 is a schematic diagram showing a relationship between an inspection area and an inspectable area.

FIG. 3 is a schematic diagram showing an example in which an inspection area is not included in an inspectable area.

FIG. 4 is a schematic diagram showing an example in which an inspection area is not included in an inspectable area.

FIG. 5 is a schematic diagram showing the principle of a foreign matter inspection method according to the present invention.

FIG. 6 is a schematic diagram showing an embodiment of a foreign matter inspection apparatus according to the present invention.

FIG. 7 is a flow chart used for explaining a foreign matter inspection method according to the present invention.

FIG. 8 is a schematic diagram showing an embodiment of a foreign matter inspection device according to the present invention.

FIG. 9 is a schematic diagram showing an embodiment of a foreign matter inspection apparatus according to the present invention.

FIG. 10 is a perspective view showing a configuration of a conventional foreign matter inspection device.

[Explanation of symbols]

1, 21, 31, 41 ... Foreign matter inspection device, 2 ... Reticle, 3 ... Pellicle, 3A ... Thin film, 3B ... Frame, 4 ... Mounting table, 5 ... Drive unit, 6 ... Length measurement Bowl, 7 ...
... light source, 8 ... optical deflection scanner, 9 ... scanning lens, 10
...... Scanning line, 11 ・ ・ ・ Foreign matter, 12, 13 ・ ・ ・ Receiving lens, 14, 15 ・ ・ ・ Photoelectric detector, 16 ・ ・ ・ Circuit pattern, 22 ・ ・ ・ Rotary table, 23, 32, 43 ・ ・ ・ Driving section, 24 ...... Rotation amount determination device, 25 …… Input device, 33
...... X direction driving unit, 34 ...... Y direction driving unit, 42 ...... Rotating unit.

Claims (6)

[Claims] 1. A foreign matter inspection apparatus for optically inspecting the surface state of the mask by scanning the surface of the mask, which is provided with a protective thin film so that foreign matter does not adhere to the surface of the mask, with a light beam. A mounting table on which the mask is mounted, a two-dimensional shape of an area to be inspected on the mask surface, and a two-dimensional shape of an area that can be actually inspected, which is determined by physical restrictions due to the presence of the protective thin film. On the basis of,
Rotating means for rotating the mask in a plane including the mask and changing a relative positional relationship of the mask with respect to a scanning direction of the light beam; A foreign matter inspection apparatus, comprising: a moving unit that relatively moves in a predetermined direction with respect to a scanning direction. 2. The rotating means rotationally moves the mounting table while the mask is still mounted on the mounting table,
The foreign matter inspection apparatus according to claim 1, wherein a relative positional relationship of the mask with respect to the scanning direction of the light beam is changed. 3. The rotating means independently rotates and moves only the mask with respect to the mounting table, and changes the relative positional relationship of the mask with respect to the scanning direction of the light beam. Item 1. The foreign matter inspection device according to item 1. 4. The rotating means is rotationally moved so that one of two sides of the protective thin film having a rectangular shape, which are orthogonal to each other, is parallel to the scanning direction of the light beam. The foreign matter inspection device according to claim 1. 5. A foreign matter inspection method for optically inspecting the surface condition of the mask by scanning the surface of the mask, which is provided with a protective thin film to prevent foreign matter from adhering to the surface of the mask, with a light beam. By the discrimination processing based on the two-dimensional shape of the area to be inspected on the surface and the two-dimensional shape of the area that can be actually inspected, which is determined by the physical constraint due to the existence of the protective thin film, the protective thin film having a rectangular shape Two orthogonal
If it is determined that the region to be inspected is not included in the actually inspectable region even if one of the sides is parallel to the scanning direction of the light beam, the inspection is performed. The mask is rotated in a plane including the mask by a predetermined angular displacement that is uniquely determined according to the two-dimensional shape of the area to be inspected and the two-dimensional shape of the actually inspectable area, and the light beam of the mask is rotated. Changing the relative positional relationship of the mask with respect to the scanning direction and then moving the mask relative to the scanning direction of the light beam in a predetermined direction to optically inspect the mask surface. . 6. A rectangle is obtained by a discrimination process based on a two-dimensional shape of an area to be inspected on the mask surface and a two-dimensional shape of an actually inspectable area which is determined by a physical constraint due to the presence of the protective thin film. The area to be inspected should be included in the area that can be actually inspected even if one of the two sides of the protective thin film having a shape orthogonal to each other is parallel to the scanning direction of the light beam. If it is determined that the mask is positioned, the mask is positioned such that one of the two sides having the shorter length is orthogonal to the scanning direction, and then the mask is scanned in the scanning direction of the light beam. 6. The foreign matter inspection method according to claim 5, wherein the mask surface is optically inspected by moving the mask surface in a predetermined direction.