JP6598737B2 - Wafer inspection equipment - Google Patents

Description

  The present invention relates to a wafer inspection apparatus.

  A conventional wafer inspection apparatus includes a stage that sucks and holds the back surface of a wafer and a drive mechanism that moves the stage. The wafer inspection apparatus sucks the back surface of the wafer onto the stage, moves the stage, determines the inspection position within the inspection surface of the wafer, and inspects from above. At this time, since the back surface of the wafer is fixed in contact with the stage, scratches and foreign matter adhere to the back surface. Therefore, the above wafer inspection apparatus is used in a manufacturing process in which generation of such scratches and foreign matters does not affect the performance of the semiconductor device.

JP 2008-131025 A

  The stage included in the wafer inspection apparatus described in Patent Document 1 has a hollow shape at the center and includes a support portion that supports the wafer on the outer periphery. Of the surface to be inspected and the back surface of the wafer, the region located inside the outer periphery supported by the support portion does not come into contact with the stage, so that the frequency of the above-described scratches and foreign matter adhesion can be reduced. However, when inspecting a wafer thinner than usual, the wafer support area is narrower than that of a conventional wafer inspection apparatus, so that the wafer vibrates due to the movement of the stage, and the inspection image is blurred. For example, when performing a mapping measurement in the wafer surface, when the scan direction is changed, excessive acceleration is applied to the wafer to generate vibration. In order to suppress such vibration, it is necessary to take measures to reduce vibration during stage driving, such as reducing the stage driving speed. Therefore, the wafer inspection apparatus that supports the outer periphery of the wafer and inspects the surface to be inspected has a problem that the inspection throughput is lower than the wafer inspection apparatus that supports the entire back surface of the surface to be inspected and inspects the inspected surface. there were.

  The present invention has been made to solve the above-described problems, and can reduce the frequency of occurrence of flaws and adhesion of foreign substances on the inspected surface and back surface of the wafer, and can increase the inspection speed of the wafer. An object of the present invention is to provide a simple wafer inspection apparatus.

The wafer inspection apparatus according to the present invention includes a support unit including a support unit that supports the outer periphery of at least a part of the wafer and can hold the wafer at the wafer installation position, and is provided to face the wafer installation position. Optical inspection means for optically inspecting a wafer to be installed, and drive means for connecting the optical inspection means and moving the optical inspection means. The support portion includes a horizontal plane that supports the outer periphery of at least a part of the wafer so that the wafer can be placed in the horizontal direction. The support portion is fixed so that the wafer installation position does not move in the horizontal direction.

  According to the wafer inspection apparatus of the present invention, it is possible to provide a wafer inspection apparatus that reduces the frequency of occurrence of flaws and foreign matter adhesion on the inspected surface and the back surface of the wafer, and improves the wafer inspection speed. is there.

1 is a diagram showing a configuration of a wafer inspection apparatus in a first embodiment. FIG. 3 is a diagram showing a configuration of a wafer holder in the first embodiment. FIG. 6 is a diagram illustrating a configuration of an objective lens and a lens protective cover in a second embodiment. FIG. 10 is a diagram illustrating an arrangement of an objective lens and a blow device in a third embodiment.

  An embodiment of a wafer inspection apparatus according to the present invention will be described. The wafer inspection apparatus mainly includes an inspection unit, a wafer transfer unit, an image processing unit, and a control unit. The wafer inspection apparatus according to the present invention relates to an inspection unit.

<Embodiment 1>
(Configuration of wafer inspection equipment)
FIG. 1 is a cross-sectional view showing a configuration of wafer inspection apparatus 100 according to the first embodiment. The wafer inspection apparatus 100 includes a housing 1 and a wafer holder 2 fixed to the housing 1. The wafer holder 2 is an example of a support unit that supports a wafer to be inspected. FIG. 2 is an enlarged view of the wafer holder 2. The wafer inspection apparatus 100 shown in FIG. 1 shows a state in which the wafer 3 is installed at the wafer installation position 2 c of the wafer holder shown in FIG. 2, and the wafer installation position 2 c in FIG. 1 corresponds to the inspection surface 3 a of the wafer 3. The wafer holder 2 includes a support portion 2a that supports the outer periphery of the wafer 3 and allows the wafer 3 to rest at the wafer installation position 2c, and a holder body 2b. The support part 2a may be configured to support the entire outer periphery of the wafer 3, or may be configured to support at least a part of the outer periphery. In the first embodiment, the wafer holder 2 includes a hollow structure 2d inside the support portion 2a as shown in FIG.

  The wafer inspection apparatus 100 further includes an optical inspection apparatus 4 provided to face the wafer installation position 2c. In the first embodiment, the optical inspection apparatus 4 is provided below the wafer installation position 2c, and optically inspects the inspection surface 3a of the wafer 3 through the hollow structure 2d described above. Although illustration of a detailed configuration of the optical inspection device 4 is omitted, in the first embodiment, the optical inspection device 4 includes an optical microscope, illumination, a camera, a z sensor, and the like. The z sensor is a sensor that detects the position of the optical inspection apparatus 4 in the z-axis direction, that is, the height direction.

  The wafer inspection apparatus 100 further includes a driving device 5 that is connected to the optical inspection apparatus 4 and moves the optical inspection apparatus 4. In the first embodiment, the driving device 5 is a driving unit that mechanically moves the inspection position of the optical inspection device 4, and the driving device 5 includes the θ · z-axis driving unit 6, the y-axis driving unit 7, and the x-axis driving. Unit 8 is included. The θ direction is the rotational direction in the xy plane. Although not shown, each drive unit includes a drive motor and a rail, and each drive unit moves on each rail by the drive of each drive motor. As a result, the optical inspection device 4 moves. Further, in order to avoid that vibration due to driving of the driving device 5 is transmitted to the wafer holder 2, the wafer inspection apparatus 100 has a vibration reducing plate 9 on a vibration transmission path connecting the wafer holder 2 and the driving device 5. Further prepare. In the first embodiment, the vibration transmission path is the housing 1 and the vibration reducing plate 9 is provided between the driving device 5 and the housing 1 as shown in FIG. In the first embodiment, the vibration transmission path is the housing 1, but the vibration transmission path may be a support structure that supports both the driving device 5 and the wafer holder 2. The support structure is provided with vibration reducing means.

(Wafer inspection operation)
In the first embodiment, as shown in FIG. 1, the wafer 3 is shown in FIG. 2 with the surface to be inspected 3a facing downward, ie, the −z direction, and the back surface 3b facing upward, ie, the + z direction. It is installed at the wafer installation position 2c. Thereby, the optical inspection device 4 faces the inspection surface 3a of the wafer 3 and can inspect the inspection surface 3a. Further, the outer periphery of the wafer 3 is supported by the support portion 2 a and is placed stationary on the wafer holder 2. In the inspected surface 3a and the back surface 3b, the region inside the support portion 2a is in a non-contact state without any other contact.

  The back surface 3b is the back side of the surface 3a to be inspected, and the relationship between the surface 3a to be inspected and the back surface 3b does not depend on the presence or absence of semiconductor devices formed on the wafer 3. The wafer 3 to be inspected is not limited to a wafer, and may be a substrate-like inspection object or an inspection object placed on a thin plate-like tray.

  The wafer inspection apparatus 100 moves the optical inspection apparatus 4 by the driving device 5 when changing the inspection position within the surface 3a to be inspected. At this time, the wafer holder 2 is not driven, and the position of the wafer 3 remains fixed. Further, the vibration due to the movement of the optical inspection apparatus 4 is reduced by the vibration reducing plate 9 to the wafer 3.

(effect)
The wafer inspection apparatus 100 can inspect the inspected surface 3a and the back surface 3b inside the support portion 2a in a non-contact state. Therefore, the wafer inspection apparatus 100 can reduce the frequency of occurrence of scratches, foreign matter adhesion, etc. on the inspected surface 3a and the back surface 3b. Further, the wafer inspection apparatus 100 can suppress the vibration of the wafer 3 and can keep the wafer 3 stationary when the inspection position is moved as compared with the conventional wafer inspection apparatus. The wafer inspection apparatus 100 can reduce the transfer of vibration due to conveyance to the wafer even when inspecting a wafer having a thinner wafer thickness than usual. As a result, the wafer inspection apparatus 100 according to the first embodiment can improve the inspection speed of the wafer 3 as compared with the conventional wafer inspection apparatus that drives the holder and stage including the wafer.

  In summary, the wafer inspection apparatus 100 according to the first embodiment supports a support unit (wafer holder) including a support portion 2a that supports at least a part of the outer periphery of the wafer 3 and can hold the wafer 3 at the wafer installation position 2c. 2), an optical inspection means (optical inspection apparatus 4) for optically inspecting the wafer 3 placed on the wafer holder 2 and provided opposite to the wafer installation position 2c, and an optical inspection connected to the optical inspection apparatus 4 Drive means (drive device 5) for moving the device 4; With the configuration as described above, the wafer inspection apparatus 100 can reduce the frequency of occurrence of scratches, adhesion of foreign matters, and the like on the inspected surface 3a and the back surface 3b of the wafer 3. In addition, since the wafer inspection apparatus 100 can reduce vibration even when the scanning direction is changed, it is not necessary to reduce the inspection speed in the operation. As a result, the wafer inspection apparatus 100 can improve the inspection speed of the wafer 3.

  Further, the support means (wafer holder 2) provided in the wafer inspection apparatus 100 of the first embodiment includes a hollow structure 2d inside the support portion 2a, and the optical inspection apparatus 4 is provided below the wafer installation position 2c. It is done. With the configuration described above, the wafer inspection apparatus 100 can inspect the inspection surface 3a from below the wafer installation position 2c by the optical inspection apparatus 4. As a result, compared with the case where the optical inspection apparatus 4 is installed above the wafer installation position 2c, the wafer inspection apparatus 100 has an occurrence frequency of foreign matters on the surface 3a to be inspected, for example, the optical inspection apparatus 4 The frequency of occurrence of foreign matter adhesion to the surface 3a to be inspected due to the driving of can be reduced.

  In the first embodiment, the configuration example of the wafer inspection apparatus 100 in which the optical inspection apparatus 4 is provided below the wafer installation position 2c is shown. However, the optical inspection apparatus 4 is provided above the wafer installation position 2c. A wafer inspection apparatus may be used, and such a wafer inspection apparatus can also reduce the vibration of the wafer 3 caused by the driving device 5. Further, when the optical inspection apparatus 4 is installed above the wafer installation position 2c, the wafer holder 2 may be configured to include a counterbore structure instead of the hollow structure 2d as described above.

  Further, the wafer inspection apparatus 100 according to the first embodiment is provided on a vibration transmission path that connects the support portion 2a and the driving device 5, and reduces the transmission of the vibration by the driving device 5 to the wafer holder 2. Vibration reducing means (vibration reducing plate 9) is further provided. With the configuration as described above, the wafer inspection apparatus 100 can reduce the frequency of occurrence of scratches, foreign matter adhesion, etc. on the inspected surface 3a or the back surface 3b due to the vibration of the driving device 5, and the wafer 3 The inspection speed can be improved.

<Embodiment 2>
A wafer inspection apparatus according to the second embodiment will be described. Note that the description of the same configuration and operation as in the first embodiment will be omitted. The wafer inspection apparatus according to the second embodiment is different from the wafer inspection apparatus described in the first embodiment in the configuration of the optical inspection apparatus 4. Other configurations are the same as those of the first embodiment. The optical inspection apparatus 4 included in the wafer inspection apparatus according to the second embodiment includes an optical microscope (not shown). FIG. 3 is a diagram showing the objective lens 13 included in the optical microscope. The optical inspection apparatus 4 includes an objective lens 13 including an optical axis in a direction perpendicular to the wafer installation position 2c, and a lens protection cover 11 on the wafer installation position 2c side of the objective lens 13. The lens protection cover 11 is fixed to the objective lens 13 by a fixture 12. The lens protective cover includes, for example, an optical element. The lens protection cover 11 is made of glass, for example. Further, the transmittance of the lens protective cover 11 is transparent in the inspection wavelength region used for the inspection of the wafer 3 by the optical inspection apparatus. For example, the transmittance of the lens protective cover 11 in the inspection wavelength region is higher than the transmittance outside the inspection wavelength region.

  In the second embodiment, the lens protection cover 11 included in the optical inspection device 4 shows an example in which the objective lens of the optical microscope included in the optical inspection device 4 is protected. For example, the optical inspection apparatus 4 may include a camera, and the optical inspection apparatus 4 may include a lens protection cover 11 that protects a lens included in the camera.

(effect)
The objective lens 13 configured in this way is acquired by the wafer inspection apparatus 100 because even if a minute deposit occurs on the surface of the lens protective cover 11, the deposit is not included in the focal depth of the objective lens 13. It is possible to reduce the reflection of foreign matter on the inspection image. Further, the lens protection cover 11 prevents the objective lens 13 from being scratched or soiled. Further, since the lens protective cover 11 is transparent in the inspection wavelength region, it does not adversely affect the inspection image.

  In summary, the optical inspection means (optical inspection apparatus 4) included in the wafer inspection apparatus of the second embodiment includes an optical lens (objective lens 13) including an optical axis in a direction perpendicular to the wafer installation position 2c, and A lens protection cover 11 is included on the wafer installation position side of the optical lens, and the lens protection cover 11 is transparent with respect to an inspection wavelength region used by the optical inspection device 4 for inspection of the wafer 3. With the configuration as described above, the wafer inspection apparatus 100 can suppress the deterioration in the quality of the inspection image due to the minute foreign matter adhering to the optical lens surface, and can maintain the inspection sensitivity.

<Embodiment 3>
A wafer inspection apparatus according to the third embodiment will be described. Note that the description of the same configuration and operation as those in Embodiment 1 or Embodiment 2 is omitted. The wafer inspection apparatus according to the third embodiment further includes a blow device 14 that injects gas to the optical lens included in the optical inspection apparatus 4 or the lens protective cover described in the third embodiment. FIG. 4 is a diagram showing an arrangement of the objective lens 13 and the blow device 14 included in the optical inspection device 4. The blow device 14 is arranged at a position away from the wafer installation position 2c shown in the first embodiment. The blowing device 14 injects a gas 15 onto the surface of the objective lens 13 or the lens protective cover 11. The gas 15 is, for example, air. Moreover, the objective lens 13 shown in FIG. 4 is an example, and the blow device 14 may inject gas to the optical lens included in the optical inspection device 4.

  The blower 14 injects the gas 15 at an angle as shown in FIG. 4 with respect to the surface of the objective lens 13 or the surface of the lens protective cover 11. As a result, the blow device 14 removes foreign matter adhering to the surface of the objective lens 13 or the lens protection cover 11. Further, the blow device 14 is installed away from the wafer installation position 2 c, thereby preventing reattachment to the wafer due to rolling up of foreign matters attached to the surface of the objective lens 13 or the lens protection cover 11.

(effect)
In summary, the wafer inspection apparatus according to the third embodiment further includes a blow device 14 that injects a gas 15 onto the optical lens (objective lens 13) or the lens protection cover 11 included in the optical inspection means. With the configuration as described above, the wafer inspection apparatus can remove the adhering matter adhering to the surface of the objective lens 13 or the lens protective cover 11 and maintain inspection sensitivity.

  It should be noted that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted.

  2 Wafer holder, 2a support part, 2b Holder body, 2c Wafer installation position, 2d Hollow structure, 3 Wafer, 3a Surface to be inspected, 3b Back surface, 4 Optical inspection device, 5 Drive device, 9 Vibration reduction plate, 11 Lens protective cover , 13 Objective lens, 14 Blow device, 15 Gas, 100 Wafer inspection device.

Claims (5)

A support means including a support portion that supports an outer periphery of at least a part of the wafer and is capable of stopping the wafer at a wafer installation position;
An optical inspection means for optically inspecting the wafer provided on the support means and provided facing the wafer installation position;
And a driving means for moving the optical inspection means connected to said optical inspection means,
The support portion includes a horizontal plane that supports the outer periphery of the at least part of the wafer so that the wafer can be placed in a horizontal direction.
Said support portion, a wafer inspection apparatus wherein the wafer installation position is that is fixed so as not to move in the horizontal direction. The support means includes a hollow structure inside the support part,
The wafer inspection apparatus according to claim 1, wherein the optical inspection unit is provided below the wafer installation position.   The vibration reduction means provided on the vibration transmission path which connects between the said support means and the said drive means, and reduces that the vibration by the said drive means transmits to the said support means is further provided. The wafer inspection apparatus described in 1. The optical inspection means includes an optical lens including an optical axis in a direction perpendicular to the wafer installation position, and a lens protection cover on the wafer installation position side of the optical lens,
4. The wafer inspection apparatus according to claim 1, wherein the lens protection cover is transparent with respect to an inspection wavelength region used by the optical inspection unit for inspection of the wafer. 5. Wafer inspection apparatus according to claim 4, further comprising a blowing device for injecting gas into the optical lens or the lens protecting cover including said optical inspection means.

Images