JPH0949789A - Chuck device and optical operation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attract and hold an object without warpage. SOLUTION: This device comprises a loop-shaped vacuum chuck mechanism 1b that sucks and holds a prescribed portion of an object 2 in a loop-shape by contacting a face of the object 2 having a cyclic structure on a transparent substrate and a pressure holding means 1f whereby ambient pressures of a space which is a side of the vacuum chuck mechanism 1b of the object 2 and is surrounded thereby and a space which is a reverse side of the vacuum chuck mechanism 1b are substantially maintained in an equal level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chuck device and an optical processing device, and more specifically, it irradiates an object having a periodic structure on a translucent substrate with parallel light. The scattered reflection light of the parallel light from the object is condensed on the spatial filter surface to attenuate the component of the scattered reflection light corresponding to the periodic structure of the object, and the transmitted light from the spatial filter surface. Further, the present invention relates to an optical processing device that collects reflected light on the surface of a light receiving part and performs necessary processing based on the output of the light receiving part, and a chuck device that is preferably applied to this optical processing device.

[0002]

2. Description of the Related Art Conventionally, when inspecting an object having a periodic structure provided on a translucent substrate, the object is irradiated with parallel light, and the parallel light is emitted by the object. The scattered reflected light of light is condensed on the spatial filter surface to attenuate the component corresponding to the periodic structure of the object in the scattered reflected light, and the transmitted light or reflected light from the spatial filter surface is received by the light receiving unit. There has been proposed an optical processing device that collects light on a surface and performs necessary processing based on the output of the light receiving unit.

Then, in the optical processing apparatus having such a structure, it is considered possible to achieve detection of a structure (defect, etc.) other than the periodic structure by gripping the object using the chuck mechanism. . However, since the target is a translucent substrate provided with a periodic structure, the target should be in close contact with the entire back surface (face to be gripped) of the target. If a chuck mechanism that grips an object is adopted, the irradiated parallel light will be reflected by the back surface of the target object and reach the light receiving surface as noise light, greatly reducing the accuracy of the optical processing. Will end up. Therefore, the chuck mechanism has a structure in which only the surplus portion provided on the peripheral portion of the object is closely held and the portion corresponding to the remaining portion is a cavity (ideally, a light absorber). You have to adopt one.

Further, even if the object does not have a light-transmitting property, the supporting member cannot be brought into contact with the surface opposite to the light incident side (when the active surface of the semiconductor wafer is on the opposite side). Etc.) still need to be provided with a cavity. As such a chucking mechanism, for example, a case where a two-sided object (one transparent substrate on which a periodic structure corresponding to two products is provided) is adopted. By forming an upward projecting ridge having a shape in which substantially central portions of a pair of opposite sides of a rectangular frame are connected, a cavity corresponding to each periodic structure is formed, and the upward projecting ridge is formed. Adopting a positioning pin provided at a predetermined position, pressing the object against the positioning pin by applying a pressing force to the object supported on the upward protruding ridge,
It is conceivable to achieve positioning of the object (see FIG. 5). Of course, when four-sided objects (one in which a periodic structure corresponding to four products is provided on one translucent substrate) are adopted, the upward projecting ridges are square frames. The same can be dealt with by adopting a chuck mechanism formed by connecting two pairs of substantially central portions facing each other.

It is also considered that a plurality of vacuum suction units made of Teflon are provided on the upper surface of the upward projecting ridges, and a chuck mechanism is provided to suck and grip an excess portion provided on the peripheral portion of the object. (See FIG. 7).

[0006]

When the chuck mechanism having the structure shown in FIG. 5 is adopted, the object is positioned by pressing it toward the positioning pin, and then the object is pressed without releasing the pressing force. Since the object is held in the positioning state, a large amount of bending occurs. As a result, although the filtering by the spatial filter can be satisfactorily achieved in a part corresponding to the center of the chuck mechanism of the object, there is a disadvantage that the filtering by the spatial filter becomes insufficient as the target area becomes closer to the chuck mechanism ( (See FIG. 6).

When the chuck mechanism having the structure shown in FIG. 7 is adopted, the surplus portion of the object is continuously sucked and held by the plurality of vacuum suction units. Therefore, the chuck mechanism having the structure shown in FIG. 5 is employed. Compared with the case, the area where the filtering by the spatial filter is successfully achieved is increasing, but it is difficult to keep the flatness of the chuck surface high, so that the filtering by the spatial filter is performed around the chuck mechanism. Is inadequate (see FIG. 8).

The measurement results shown in FIGS. 6 and 8 are obtained as follows, for example. A spatial filter is created near the center of the measurement area by exposure, etc., and the entire surface of the object is scanned with the spatial filter thus created attached to a predetermined position, and the space of light caused by the periodic structure is scanned. The leakage from the filter was quantified while observing with a CCD camera. In addition, when quantifying,
The amount of light leaked from the spatial filter due to the periodic structure is
For example, since it is obtained as shown in FIG. 9, the average value of the amount of leaked light due to the periodic structure {the added average value (a + b) / the maximum value a of the top peak and the minimum value b of the top peak of the amount of leaked light / 2 and a and b are as shown in FIG. 9}, and the brightness level obtained by subtracting the dark part image reception signal level (the minimum value c of the amount of leaked light, c is as shown in FIG. 9) as an offset from Indicated by. Therefore, the larger this value is, the poorer the matching with the spatial filter is, and the light due to the periodic structure leaks. Further, the numerical values shown in FIG. 8 in FIG. 6 are values calculated based on the output of the image processing apparatus represented by gradations of 0 to 255.

As a result, the light caused by the periodic structure can be cut with high accuracy in the vicinity of the center where the spatial filter is manufactured, but it can be evaluated that the amount of leaked light is large in the surroundings. Here, the leaked light is generated as follows. That is, for example, by bending the object,
The Fourier transform pattern moves laterally according to the inclination of the object (local inclination caused by bending), and it becomes impossible to match with the spatial filter prepared by pre-exposure and development. Will be cut incompletely. Specifically, when a Fourier transform lens having a focal length of 300 mm is used, the Fourier transform pattern moves laterally by 0.52 mm only when the object is tilted by 0.05 °.
Further, since the spot interval of the spatial filter corresponding to the periodic structure of 100 μm is 1.45 mm, 0.52 m
The lateral movement of m is equivalent to the Fourier transform pattern being shifted by almost a half cycle, and the light due to the periodic structure leaks, making measurement impossible. That is, the fatal inconvenience as described above occurs when the object is tilted by a few hundredths.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a chuck mechanism capable of stably gripping an object without causing the object to bend substantially. A second object of the present invention is to provide an optical processing apparatus capable of stably gripping an object and improving the accuracy of optical processing with almost no bending of the object.

[0011]

According to a first aspect of the present invention, there is provided a chuck mechanism comprising: a loop-shaped vacuum chuck mechanism which is in contact with a surface of an object and sucks and holds a predetermined position of the object in a loop shape; A holding pressure for keeping the atmospheric pressure of the space on the chuck mechanism side and surrounded by the vacuum chuck mechanism substantially equal to or higher than the atmospheric pressure in the space of the object opposite to the vacuum chuck mechanism. And means.

According to another aspect of the optical processing apparatus of the present invention, an object having a periodic structure provided on a light-transmitting substrate is irradiated with parallel light, and scattered light reflected by the object is reflected. Of the scattered reflected light, the components corresponding to the periodic structure of the object are attenuated by being condensed on the spatial filter surface, and the transmitted light or the reflected light from the spatial filter surface is condensed on the light receiving surface. An optical processing device that performs necessary processing based on an output of the light receiving unit, the loop-shaped vacuum chuck mechanism that is in contact with the object surface and sucks and holds a predetermined position of the object in a loop shape, The atmospheric pressure of the space of the object on the side of the vacuum chuck mechanism and surrounded by the vacuum chuck mechanism is substantially the same as the atmospheric pressure of the space of the object on the side opposite to the vacuum chuck mechanism. A pressure holding means to keep above It has.

[0013]

According to the chuck mechanism of claim 1, since the chuck mechanism has a loop-shaped vacuum chuck mechanism which is in contact with the surface of the object and sucks and holds a predetermined position of the object in a loop, In addition to being able to reliably suck and grip the object, the part surrounded by the vacuum chuck mechanism is a space, so compared to the case where the entire surface of the object is gripped, when the object is irradiated with light, the object It is possible to significantly suppress an increase in reflection on the back surface of the. The atmospheric pressure of the space of the object on the vacuum chuck mechanism side and surrounded by the vacuum chuck mechanism is substantially equal to the atmospheric pressure in the space of the object on the side opposite to the vacuum chuck mechanism. Since the vacuum chuck mechanism has a pressure holding means that keeps the same or more, the atmospheric pressure in the space surrounded by the vacuum chuck mechanism is reduced while the object is sucked and gripped by the vacuum chuck mechanism. It is possible to reliably prevent the occurrence of. Therefore, the object can be stably sucked and gripped with almost no bending of the object. When the vacuum chuck mechanism is on the side of gravity (lower side) with respect to the object, the atmospheric pressure on the lower side of the object is set to be slightly higher than that on the upper side to cancel the deflection of the object due to gravity. You may. Conversely, when the chuck mechanism is on the upper side, the atmospheric pressure on that side may be slightly lowered.

According to the optical processing apparatus of claim 2, parallel light is irradiated onto an object having a periodic structure provided on a transparent substrate, and the parallel light is scattered and reflected by the object. Of the scattered reflected light by condensing light on the spatial filter surface,
Attenuating the component corresponding to the periodic structure of the object,
In collecting the transmitted light or reflected light from the spatial filter surface on the one-dimensional sensor surface or the two-dimensional sensor surface and performing necessary processing based on the output of the light receiving unit, a loop-shaped vacuum chuck mechanism By this, since the predetermined position of the target object is sucked and gripped in contact with the target surface in a loop shape, the peripheral portion of the target object can be securely sucked and gripped and is surrounded by the vacuum chuck mechanism. Since the portion is a space, an increase in reflection on the back surface of the object can be significantly suppressed when the object is irradiated with light, as compared with the case where the entire surface of the object is grasped. And
The atmospheric pressure of the space of the object on the vacuum chuck mechanism side and surrounded by the vacuum chuck mechanism is substantially equal to the atmospheric pressure of the space of the object on the side opposite to the vacuum chuck mechanism. Since the pressure holding means for keeping the same or more is provided, while the target object is sucked and gripped by the vacuum chuck mechanism, the atmospheric pressure of the space surrounded by the vacuum chuck mechanism is lowered and the target object is bent. It can be reliably prevented. Therefore, the object can be stably sucked and gripped with almost no bending of the object. As a result, light caused by the periodic structure of the object can be reliably blocked or transmitted by the spatial filter, and high-precision optical processing (such as defect inspection) can be performed based on the light transmitted through the spatial filter. it can.

[0015]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a perspective view showing an embodiment of a chuck mechanism of the present invention, and FIG. 2 is a vertical sectional view schematically showing a main part. In this chuck mechanism 1, an endless groove 1b is formed in the center of the upper surface of all the side wall bodies 1a of a rectangular parallelepiped frame body having an open upper surface, and predetermined positions of the groove 1b communicate with each other at a plurality of locations. Hole 1
It is communicated with the vacuum suction path 1d via c. The vacuum suction passage 1d is connected to a vacuum pump (not shown).
Further, a hole 1f as a pressure holding means is formed at a predetermined position of the bottom plate 1e of the frame. Of course, the upper surfaces of all the side walls 1a are chuck surfaces for gripping the object 2, and thus are finished to have high flatness.

The chuck mechanism 1 has a structure corresponding to an object 2 on which one product is mounted on a transparent substrate, but two products are mounted on a transparent substrate. With respect to the target object 2 that is present, for example, a chuck mechanism in which the side wall body 1a is provided in a shape in which substantially central portions of a pair of opposing sides of a rectangular frame are connected to each other may be adopted, and the translucent For an object 2 on which four products are placed on a certain substrate, for example, a chuck mechanism is provided in which a side wall body 1a is provided in a shape in which two pairs of facing substantially central portions of a rectangular frame are connected to each other. You can use it. Further, instead of the vent hole 1f, a piston or the like that can be actively operated to compensate for an unnecessary pressure drop accompanying the operation of the vacuum pump may be adopted as the pressure maintaining means. In this case, it is possible to compensate the deflection of the object 2 due to gravity.

When the object 2 is sucked and gripped by using the chuck mechanism having the above-mentioned structure, while the object 2 is sucked and gripped by the groove 1b communicating with a vacuum pump (not shown), an arrow in FIG. , The chuck surface and the object 2
A small amount of air is sucked in between
Since the vent hole 1f as a pressure-holding means is formed at a predetermined position of the bottom plate body 1e of the frame body, only the inside of the frame body does not have a remarkably low pressure. Are almost equal to each other. Therefore, the occurrence of bending due to the pressure difference is prevented in advance, and the entire outer circumferential circle of the object 2 is suction-held by the groove 1b, so that the object 2 can maintain a high flatness. Further, since the object 2 is only in close contact with the chuck surface, the inside of the object 2 is not in contact with the chuck mechanism 1 as compared with the part in close contact with the chuck surface, and therefore the back surface reflection is caused in this part. Is extremely small and has little effect on optical processing.

The object 2 is suction-held by using the chuck mechanism having the side wall 1a provided in the shape of a letter, and the degree of filtering is confirmed by performing the same measurement as in FIGS. 5 and 7. It was as shown. Comparing FIG. 3 with FIG. 6 and FIG. 8, by adopting this embodiment, the flatness of the object 2 is advanced, the region with less deflection is increased, and the matching with the spatial filter is improved. I know that

FIG. 4 is a schematic view showing an embodiment of an optical processing apparatus incorporating the chuck mechanism having the structure shown in FIG. As the optical processing apparatus, an apparatus for inspecting a structure (defect or the like) other than the periodic structure of the object 2 is illustrated. This optical processing apparatus includes a chuck mechanism 1 for adsorbing and gripping an object 2 having a periodic structure provided on a transparent substrate, and a parallel light source for irradiating the surface of the object 2 with parallel light ( (Not shown), a Fourier transform lens 3 for optically Fourier transforming scattered and reflected light from the surface of the object 2, and a spatial filter (space) for collecting the light Fourier-transformed by the Fourier transform lens on the surface. A frequency filter) 4, an inverse Fourier transform lens 5 for performing an inverse Fourier transform on the light transmitted through the spatial filter 4, and a light receiving section 6 on which the light subjected to the inverse Fourier transform by the inverse Fourier transform lens 5 is condensed on the surface thereof. The signal processing unit 7 performs necessary processing based on the output from the light receiving unit 6.

The chuck mechanism 1 has a mechanism as shown in FIG. 1, and the chuck mechanism 1 has an xy stage (not shown) for two-dimensionally moving the object 2. ) And a θ stage (not shown) for rotating the object 2 in this order. Specifically, for example, the xy stage is supported on the θ stage, and the chuck mechanism 1 is supported on the xy stage.

The Fourier transform lens 3 is for converting the position-dependent reflected light intensity from the object 2 into a frequency-dependent light intensity, and the specific structure of such a Fourier transform lens is Since it is well known in the art, detailed description will be omitted. The inverse Fourier transform lens 5 has a function opposite to that of the Fourier transform lens 3, and since the specific configuration of such a Fourier transform lens is well known in the art, detailed description thereof will be omitted.

The spatial filter 4 is, for example, an object 2
Has an opaque pattern formed at a position corresponding to an image obtained by Fourier-transforming the scattered reflected light caused by the periodic structure of the object 2, and the opaque pattern of the object 2 and the spatial filter 4 is accurate. It is possible to block the scattered reflected light caused by the periodic structure on condition that the light is positioned at. However, instead of the opaque pattern, a transparent pattern may be adopted to make the remaining region opaque, and in this case, only the scattered reflected light due to the periodic structure can be transmitted.

The light receiving unit 6 receives light in a predetermined range and outputs a signal corresponding to the intensity of the received light, and can be exemplified by a one-dimensional sensor such as a CCD camera or a two-dimensional sensor. . The signal processing unit 7 receives the signal from the light receiving unit 6 and performs a predetermined process to output a processing result signal. Here, the predetermined processing is
For example, in the case of detecting a structure (defect) other than the periodic structure of the object 2, an image corresponding to the defect is extracted by performing connectivity analysis or the like as is conventionally known, and an image corresponding to the defect is obtained. On the condition that the object 2 is extracted, a signal indicating that the object 2 has a defect is output, and in response to the fact that the image corresponding to the defect is not extracted, the object 2 has a defect. It outputs a signal indicating that it is not. When processing other than the defect inspection is performed, conventionally known processing is performed according to the processing to be performed.

The operation of this optical processing device is as follows. First, similarly to the embodiment shown in FIG. 1, the object 2 is sucked and gripped by the chuck device 1 in a state in which the object 2 hardly bends. Further, the object 2 is two-dimensionally positioned and rotationally positioned by the xy stage and the θ stage as required, and the positioning of the periodic structure of the object 2 and the filter pattern of the spatial filter 4 is achieved. It Note that this positioning may be appropriately performed during the subsequent processing.

After that, a parallel light source (not shown) irradiates the surface of the object 2 with parallel light, and the scattered reflected light is Fourier transformed by the Fourier transform lens 3 to be condensed on the surface of the spatial filter 4. In this case, since the object 2 hardly bends, the Fourier transform component due to the periodic structure is effectively shielded by the pattern of the spatial filter 4. Then, the light transmitted through the spatial filter 4 is subjected to the inverse Fourier transform by the inverse Fourier transform lens 5 and condensed on the surface of the light receiving portion 6. Therefore, when the object 2 has a structure (defect) other than the periodic structure, an image corresponding to the defect is formed on the light receiving portion 6 surface, and a signal corresponding to the image on the light receiving portion 6 surface is received. It is output from the unit 6. Then, in the signal processing unit 7, for example, an image corresponding to the defect is extracted by performing connectivity analysis or the like, and the defect exists in the object 2 on condition that the image corresponding to the defect is extracted. A signal indicating that the object 2 does not have a defect is output in response to the fact that an image corresponding to the defect has not been extracted.

As a result, it is possible to achieve accurate defect detection due to almost no occurrence of bending in the suction grip state of the object 2. Of course, when the processing content of the signal processing unit 7 is set to perform processing other than the defect inspection, the requested processing result signal can be output by performing the set processing.

[0027]

According to the first aspect of the present invention, the peripheral portion of the object can be securely sucked and gripped, and the object is irradiated with light as compared with the case where the entire surface of the object is gripped. The increase in reflection on the back surface of the object can be significantly suppressed, and while the object is sucked and held by the vacuum chuck mechanism, the atmospheric pressure of the space surrounded by the vacuum chuck mechanism is reduced to reduce the object pressure. It is possible to surely prevent the bending of the object, and it is possible to stably suck and grasp the object without causing the object to bend.

According to the second aspect of the present invention, the peripheral portion of the object can be surely sucked and gripped, and the object is irradiated with light as compared with the case where the entire surface of the object is gripped. The increase in reflection on the back surface of the vacuum chuck mechanism can be significantly suppressed, and the atmospheric pressure of the space surrounded by the vacuum chuck mechanism decreases while the object is sucked and gripped by the vacuum chuck mechanism, so that the flexure Can be reliably prevented from occurring, and by extension, the object can be stably attracted and gripped with almost no bending, and the light caused by the periodic structure of the object can be spatially absorbed. Filters ensure blocking or transmission,
There is a unique effect that high-precision optical processing (such as defect inspection) can be performed based on the light that has passed through the spatial filter.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a chuck mechanism of the present invention.

FIG. 2 is a vertical cross-sectional view schematically showing a main part of the above.

FIG. 3 is a diagram showing a measurement result showing the flatness of an object suction-held by a chuck mechanism.

FIG. 4 is a schematic view showing an embodiment of an optical processing apparatus incorporating the chuck mechanism having the configuration shown in FIG.

FIG. 5 is a perspective view showing a schematic configuration of a conventional chuck mechanism configured to simply support an object in a positioned state.

6 is a diagram showing a measurement result showing the flatness of an object supported by the chuck mechanism of FIG.

FIG. 7 is a perspective view showing a schematic configuration of a conventional chuck mechanism adapted to suck and grip a peripheral portion of an object.

8 is a diagram showing a measurement result showing the flatness of an object suction-held by the chuck mechanism of FIG.

FIG. 9 is a diagram showing a change in the amount of leaked light from a spatial filter due to a periodic structure.

[Explanation of symbols]

 1b Groove 1f Hole 2 Object 4 Spatial filter 6 Light receiving part

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H01L 21/68 H01L 21/68 P

Claims (2)

[Claims] 1. The object (2) in contact with the surface of the object (2)
And a loop-shaped vacuum chuck mechanism (1b) for sucking and gripping a predetermined position of the object in a loop shape, and surrounding the object (2) on the vacuum chuck mechanism (1b) side and by the vacuum chuck mechanism (1b). And a pressure holding means (1f) for keeping the atmospheric pressure of the space in the space opposite to the vacuum chuck mechanism (1b) of the object (2) substantially equal to or higher than the atmospheric pressure. The chuck device is characterized in that. 2. An object (2) having a periodic structure provided on a transparent substrate is irradiated with parallel light, and the scattered reflection light of the parallel light by the object (2) is spatially reflected. Of the scattered reflected light, components corresponding to the periodic structure of the object (2) are attenuated by condensing on the filter (4) surface, and transmitted light or reflected light from the spatial filter (4) surface is attenuated. An optical processing device for condensing light on a surface of a light receiving section (6) and performing necessary processing based on an output of the light receiving section (6), the object (2) being in contact with the surface of the object (2). ) A loop-shaped vacuum chuck mechanism (1b) that sucks and holds a predetermined position of
And the vacuum chuck mechanism (1b) for the object (2)
The atmospheric pressure of the space which is on the side and surrounded by the vacuum chuck mechanism (1b) is substantially equal to the atmospheric pressure in the space of the object (2) opposite to the vacuum chuck mechanism (1b). An optical processing device, characterized in that it has a pressure holding means (1f) for keeping the same or more.