JP2011122934A - Inspection method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection method capable of managing position information of a film with high accuracy. <P>SOLUTION: The inspection method for inspecting the periphery of the end of a wafer having a film formed on the surface includes: a first step (S101) for detecting the end position of the wafer; a second step (S104) for imaging the periphery of the end of the wafer on the end position of the wafer detected beforehand, and detecting the end position of the film from an image of the periphery of the end of the wafer; and a third step (S106) for determining a distance between the end of the wafer along the radius direction of the wafer and the end of the film from the end position of the wafer and the end position of the film detected respectively in the preceding step, and inspecting existence of an abnormality on the periphery of the end of the wafer based on the distance. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an inspection method and an inspection apparatus for inspecting the vicinity of an end portion of a substrate such as a semiconductor wafer or a liquid crystal glass substrate.

  In recent years, the degree of integration of circuit element patterns formed on semiconductor wafers has increased, and the types of films used for wafer surface treatment in semiconductor manufacturing processes have increased. Along with this, inspection near the outer peripheral edge of the wafer located at the boundary of the film has become important. That is, defect management near the edge of the wafer affects the yield of circuit elements created from the wafer.

  Therefore, the periphery of the outer edge of the substrate formed in a disk shape such as a semiconductor wafer (eg apex and upper and lower bevels) is observed from a plurality of directions to remove foreign substances and films, bubbles in the film, and wraparound of the film. The presence or absence of abnormalities such as the above is inspected (see, for example, Patent Document 1). In addition, for the purpose of managing the EBR process and the coating state of the film, the film end position may be sampled at a plurality of locations to manage the film position.

Japanese Patent No. 3941375

  However, when the vicinity of the edge of the wafer is imaged by an imaging system using epi-illumination, a reflection image by the epi-illumination is captured, so that the end of the wafer cannot be detected depending on the inclination angle of the bevel. Therefore, the distance from the end of the wafer to the end of the film cannot be accurately grasped, and there is a possibility that the position of the film cannot be managed appropriately.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide an inspection method and an inspection apparatus capable of accurately managing film position information.

  In order to achieve such an object, an inspection method according to the present invention is an inspection method for inspecting the vicinity of an end portion of a disk-shaped substrate having a film that substantially covers one flat surface portion. A first step of detecting a position; a second step of imaging the vicinity of the end of the substrate including the end of the film at the end position of the substrate detected in the first step; A third step of detecting an end position of the film from an image in the vicinity of the end of the substrate imaged in the step, and an end position of the substrate and the film detected in the first and third steps, respectively. A fourth step of obtaining a distance between the edge of the substrate and the edge of the film along the radial direction of the substrate from the edge position of the substrate, and the edge of the substrate obtained in the fourth step Based on the distance between the part and the end of the membrane, And a fifth step of inspecting the presence or absence of abnormality in the vicinity of the end portion of the plate.

  In the inspection method described above, in the first step, the end position of the substrate is detected over the entire circumference of the substrate while rotating the substrate, and in the second step, the substrate is rotated. While imaging the vicinity of the edge of the substrate over the entire circumference of the substrate, detecting the edge position of the film over the entire circumference of the substrate in the third step, and in the fourth step, The distance between the edge of the substrate and the edge of the film along the radial direction of the substrate over the entire circumference of the substrate was obtained, and was obtained over the entire circumference of the substrate in the fifth step. It is preferable to inspect whether there is an abnormality in the vicinity of the end of the substrate based on the distance between the end of the substrate and the end of the film.

  The inspection apparatus according to the present invention is an inspection apparatus for inspecting the vicinity of an end portion of a disk-shaped substrate having a film that substantially covers one flat surface portion, and detects the end position of the substrate. An imaging unit that images the vicinity of the edge of the substrate including the edge of the film at the edge position of the substrate detected by the first detection unit, and the substrate imaged by the imaging unit A second detection unit that detects an end position of the film from an image in the vicinity of the end of the substrate, an end position of the substrate detected by the first and second detection units, and an end position of the film A calculation unit for obtaining a distance between the end of the substrate and the end of the film along a radial direction of the substrate, and an end of the substrate and the end of the film obtained by the calculation unit. And an inspection unit for inspecting the presence or absence of an abnormality in the vicinity of the end portion of the substrate based on the distance between them. That.

  The inspection apparatus includes a support unit that rotatably supports the substrate, and the first detection unit rotates the substrate by the support unit and rotates the substrate over the entire circumference of the substrate. Detecting the position of the substrate, the imaging unit images the vicinity of the end of the substrate over the entire circumference of the substrate while rotating the substrate by the support unit, and the second detection unit Detecting the position of the edge of the film over the circumference, and the computing unit calculates a distance between the edge of the substrate and the edge of the film along the radial direction of the substrate over the entire circumference of the substrate. The inspection unit inspects whether there is an abnormality in the vicinity of the end portion of the substrate based on the distance between the end portion of the substrate and the end portion of the film obtained over the entire circumference of the substrate. It is preferable.

  According to the present invention, the position information of the film can be managed with high accuracy.

It is a flowchart of the inspection method which concerns on this embodiment. It is a schematic block diagram of the inspection apparatus which concerns on this embodiment. It is a top view of a wafer. It is a figure which shows an example of the visual field in an imaging part. It is a side view which shows the outer periphery edge part vicinity of a wafer. It is a figure which shows the relationship between the center of a wafer, and a visual field. It is a side view which shows the modification of an inspection apparatus.

  Hereinafter, preferred embodiments of the present invention will be described. An example of an inspection apparatus according to the present invention is shown in FIG. 2, and the inspection apparatus 1 is for inspecting for the presence or absence of an abnormality in the outer peripheral end portion of the semiconductor wafer 10 (hereinafter referred to as the wafer 10) and in the vicinity of the outer peripheral end portion. belongs to.

  A wafer 10 as a test substrate is formed in a thin disk shape, and a circuit pattern (not shown) corresponding to a plurality of semiconductor chips (chip regions) taken out from the wafer 10 is formed on the surface (mainly a flat portion). For example, a resist film 15 is formed. As shown in FIG. 5, an upper bevel portion 11 inclined to the outer peripheral side is formed in a ring shape inside the outer peripheral end portion on the surface (upper surface) of the wafer 10, and a circuit pattern is formed inside the upper bevel portion 11. Will be. Further, a lower bevel portion 12 is formed symmetrically with the upper bevel portion 11 with respect to the wafer 10 on the inner side of the outer peripheral end portion on the back surface (lower surface) of the wafer 10. The wafer end connected to the upper bevel portion 11 and the lower bevel portion 12 becomes an apex portion 13.

  By the way, as shown in FIG. 2, the surface inspection apparatus 1 includes a wafer support unit 20 that supports and rotates the wafer 10, an alignment unit 30 that detects an end position of the wafer 10, and an outer peripheral end of the wafer 10. An image pickup unit 40 that picks up the image and the vicinity of the outer peripheral edge, and a data processing unit 50 that performs predetermined data processing on data input from the alignment unit 30 and the image pickup unit 40 are configured.

  The wafer support unit 20 includes an X stage 21, a Y stage 22 provided on the X stage 21, and a θ stage 23 provided on the Y stage 22 and supporting the wafer 10. The θ stage 23 has an upper support surface formed in a substantially circular shape, and supports the wafer 10 rotatably about the center of the wafer 10. A vacuum suction mechanism (not shown) is provided inside the θ stage 23, and the wafer 10 on the θ stage 23 is suction-held using vacuum suction by the vacuum suction mechanism. The wafer 10 has a larger diameter than the support surface of the θ stage 23, and the upper bevel portion 11, the lower bevel portion 12, and the apex portion 13 with the wafer 10 being sucked and held on the θ stage 23. The vicinity of the outer peripheral end portion of the wafer 10 including is protruded from the θ stage 23. The X stage 21 and the Y stage 22 respectively drive the θ stage 23 in a two-dimensional direction to move the wafer 10 sucked and held on the θ stage 23 vertically and horizontally in a substantially horizontal plane.

  The alignment unit 30 includes a transmission illumination unit 31 and a line sensor 32. The transmitted illumination unit 31 is disposed along the radial direction of the wafer 10 (θ stage 23) on the side of the wafer support unit 20, and is illumination light that is parallel light from below the wafer 10 to the vicinity of the outer peripheral end of the wafer 10. Irradiate. The line sensor 32 is disposed above the wafer support unit 20 along the radial direction of the wafer 10 (θ stage 23), and detects illumination light from the transmission illumination unit 31 that has passed through the wafer 10. Accordingly, the line sensor 32 is arranged so as to face the transmission illumination unit 31 with the wafer 10 interposed therebetween, and is configured to detect parallel light (illumination light) from the transmission illumination unit 31. The end position of the wafer 10 along the radial direction of the wafer 10 can be detected from the information on the light detected at 32 (the position where the illumination light blocked by the wafer 10 is detected).

  Further, when the wafer 10 supported by the wafer support unit 20 is rotated, the outer peripheral end portion of the wafer 10 is rotated relative to the line sensor 32 in the circumferential direction of the wafer 10. It is possible to detect the end position of the wafer 10 over the entire area. The detection data obtained by the line sensor 32 is output to the data processing unit 50.

  The imaging unit 40 is disposed above the wafer support unit 20 so as to face the upper bevel unit 11 of the wafer 10, and includes an epi-illumination unit 41 and an image sensor 42. When illumination light from the epi-illumination unit 41 is irradiated to the vicinity of the outer peripheral end of the wafer 10 via an imaging optical system (not shown), reflected light from the wafer 10 is guided to the image sensor 42 by the imaging optical system, and the imaging optical system. As a result, a reflection image in the vicinity of the outer peripheral end portion of the wafer 10 including the upper bevel portion 11 and the end portion of the resist film 15 is formed on the imaging surface of the image sensor 42. Then, the image sensor 42 captures a reflection image near the outer peripheral edge of the wafer 10 and outputs image data near the outer peripheral edge of the wafer 10 to the data processing unit 50. When the wafer 10 supported by the wafer support unit 20 is rotated, the outer peripheral end of the wafer 10 rotates relative to the imaging region of the imaging unit 40 in the circumferential direction of the wafer 10. A plurality of images can be continuously captured in the circumferential direction (that is, the relative rotation direction), and the vicinity of the outer peripheral end of the wafer 10 can be imaged over the entire circumference of the wafer 10.

  The data processing unit 50 detects the end position of the wafer 10 along the radial direction of the wafer 10 from the detection data input from the line sensor 32, and detects the position of the wafer 10 in the radial direction of the wafer 10 from the image data input from the image sensor 42. The position of the end of the resist film 15 is detected. When the data processing unit 50 detects the end position of the wafer 10 and the end position of the resist film 15, based on these, the end of the wafer 10 and the end of the resist film 15 along the radial direction of the wafer 10 are detected. And the presence or absence of abnormality in the vicinity of the outer peripheral end of the wafer 10 based on the distance between the end of the wafer 10 and the end of the resist film 15 obtained over the entire circumference of the wafer 10. (Details will be described later).

  A method for inspecting the vicinity of the end of the wafer 10 using the inspection apparatus 1 configured as described above will be described with reference to the flowchart shown in FIG. First, the position data of the edge position of the wafer 10 is acquired using the line sensor 32 which is a transmission type sensor (step S101). At this time, the transmissive illumination unit 31 irradiates illumination light as parallel light near the outer peripheral end of the wafer 10 from below the wafer 10 supported by the wafer support unit 20, and the line sensor 32 passes through the wafer 10. The illumination light from the transmitted illumination unit 31 is detected and the detection data is output to the data processing unit 50. Then, the data processing unit 50 obtains the outer diameter reference position from the detection data input from the line sensor 32, detects the end position of the wafer 10, and uses the detected position data of the end position of the wafer 10 as the outer diameter. The data is stored in an internal memory (not shown) based on the reference position.

  At this time, the wafer 10 supported by the wafer support unit 20 (θ stage 23) is rotated, and the end position of the wafer 10 is detected at every predetermined rotation angle (for example, 1 degree). Position data of the end position of the wafer 10 over the entire circumference is repeatedly acquired (step S102). In order to obtain the position shape of the wafer 10 as a circle, the number of data acquisitions is preferably 3 or more.

  Next, the data processing unit 50 obtains the center position of the wafer 10 from the position data of the end position of the wafer 10 acquired in steps S101 and S102 (step S103). Further, the data processing unit 50 obtains an eccentric amount between the center of the wafer 10 and the rotation center of the wafer support unit 20 (θ stage 23) obtained in advance, and according to the obtained eccentric amount, The position data of the edge position of the wafer 10 acquired in the step is corrected so as to be the position data of the edge position of the wafer 10 with the center of the wafer 10 as a reference.

  Next, the position data of the end position of the resist film 15 is acquired using the image sensor 42 which is a reflection type sensor (step S104). At this time, illumination light from the epi-illumination unit 41 is irradiated to the vicinity of the outer peripheral end of the wafer 10 via an imaging optical system (not shown) of the imaging unit 40, and reflected light from the wafer 10 is image sensor by the imaging optical system. The reflected image in the vicinity of the outer peripheral end of the wafer 10 including the upper bevel portion 11 and the end portion of the resist film 15 is formed on the imaging surface of the image sensor 42 by the imaging optical system. Therefore, the image sensor 42 captures a reflected image near the outer peripheral edge of the wafer 10 and outputs image data near the outer peripheral edge of the wafer 10 to the data processing unit 50. Then, the data processing unit 50 detects the end position and the outer diameter reference position of the resist film 15 along the radial direction of the wafer 10 from the image data input from the image sensor 42, and the detected end part of the resist film 15. The position data of the position is stored in an internal memory (not shown) on the basis of the outer diameter reference position.

  Further, at this time, the wafer 10 supported by the wafer support unit 20 (θ stage 23) is rotated, and the end position of the resist film 15 is detected at every predetermined rotation angle (for example, 1 degree). The position data of the end position of the resist film 15 over the entire circumference is repeatedly acquired (step S105). Note that when the wafer 10 is rotated by the θ stage 23, the X stage 21 and the Y stage 22 are located near the outer peripheral end of the wafer 10 regardless of the eccentricity between the center of the wafer 10 and the rotation center of the θ stage 23. The wafer 10 on the θ stage 23 is moved in a substantially horizontal plane in accordance with the amount of eccentricity obtained in the previous step so that imaging can be performed with a fixed relative positional relationship.

  Next, when the data processing unit 50 detects the end position of the wafer 10 and the end position of the resist film 15, based on these, the end of the wafer 10 and the end of the resist film 15 along the radial direction of the wafer 10 are detected. The distance to the part is obtained (step S105). At this time, the distance between the end of the wafer 10 and the end of the resist film 15 is obtained over the entire circumference of the wafer 10 at every predetermined rotation angle (for example, 1 degree) described above.

  Incidentally, the field of view FOV (imaging range) in the imaging unit 40 is shown in FIGS. As described above, when the vicinity of the outer peripheral edge of the wafer 10 is imaged by the imaging unit 40 using the epi-illumination unit 41, a reflection image by the epi-illumination is captured. The part position C cannot be detected. As shown in FIG. 5, the end position B of the wafer 10 reflected in the field of view FOV is the position of the boundary portion (with the flat portion of the wafer 10) of the upper bevel portion 11. On the other hand, since the alignment unit 30 uses transmitted illumination (telecentric optical system) using parallel light, as shown in FIG. 5, the line sensor 32 detects the position where the detected signal intensity rises. The end position C of the wafer 10 can be detected, and the end position C of the wafer 10 along the radial direction of the wafer 10 with reference to the center P of the wafer 10 as shown in FIG. . The end position C of the wafer 10 at this time is the position of the intersection point Q between the radial line of the wafer 10 and the outer peripheral end of the wafer 10. Further, as shown in FIG. 5, the end position A of the resist film 15 can be detected by detecting the position where the signal intensity greatly changes in the image sensor 42 (image near the outer peripheral end of the wafer 10). it can. Therefore, by using the position data of the edge position C of the wafer 10 detected using the line sensor 32 and the position data of the edge position A of the resist film 15 detected using the image sensor 42, the radius of the wafer 10 is obtained. The distance between the end of the wafer 10 and the end of the resist film 15 along the direction can be obtained with high accuracy. For comparison, in FIGS. 2, 3, 4, and 6, the outer peripheral end portion (apex portion 13) of the wafer 10 is indicated by a broken line.

  Then, the data processing unit 50 determines whether there is an abnormality near the outer peripheral end of the wafer 10 based on the distance between the end of the wafer 10 and the end of the resist film 15 obtained over the entire circumference of the wafer 10. Inspect. At this time, for example, a standard deviation (or 3σ) for the distance obtained for each predetermined rotation angle is obtained, and if the obtained standard deviation is larger than a predetermined value, it is determined that there is an abnormality, and this is notified. As a result, it is possible to detect a shape collapse or the like generated at the end of the resist film 15. Alternatively, the distance obtained for each predetermined rotation angle may be subjected to frequency conversion by an FFT analyzer (not shown) or the like, and when a frequency component higher than the predetermined frequency is detected, it may be determined that there is an abnormality. . Thereby, it is possible to detect fine undulations and the like generated at the end of the resist film 15.

  As a result, according to the present embodiment, the distance between the end portion of the wafer 10 and the end portion of the resist film 15 is obtained based on the end portion position of the wafer 10 detected using the line sensor 32 for alignment. Therefore, since the end position of the wafer 10 can be detected accurately, the position information of the film can be managed with high accuracy, and the inspection accuracy can be improved. If the distance between the end of the wafer 10 and the end of the resist film 15 is obtained over the entire circumference of the wafer 10, the position information of the film can be managed with higher accuracy.

  In the above-described embodiment, as shown in FIG. 7, the vicinity of the outer peripheral edge of the wafer 10 (upper bevel portion 11 and the like) is formed on the side of the wafer support 20 (θ stage 23) from the side of the wafer 10. A bevel illumination device 60 that performs diffuse illumination may be provided. In this way, since not only epi-illumination but also diffuse illumination is performed on the inclined upper bevel portion 11, the upper bevel portion 11 can be clearly imaged by using the imaging portion 40, and the imaging portion 40 can be imaged. It is possible to accurately detect the end position A of the resist film 15 reaching the upper bevel portion 11 from the image in the vicinity of the outer peripheral end portion of the wafer 10 picked up. Note that the end position C of the wafer 10 is detected using the line sensor 32 as in the above-described embodiment, but depending on the inclination of the upper bevel unit 11 and the imaging magnification, the diffused illumination is used for the imaging unit 40. It is also possible to detect from the image of the vicinity of the outer peripheral edge of the imaged wafer 10.

  In the above-described embodiment, the resist film 15 is formed on the surface of the wafer 10. However, the present invention is not limited to this. For example, a film such as a so-called top coat may be provided.

  In the above-described embodiment, the wafer 10 is inspected. However, the present invention is not limited to this. For example, a substrate such as a liquid crystal glass substrate may be inspected.

DESCRIPTION OF SYMBOLS 1 Inspection apparatus 10 Semiconductor wafer (board | substrate) 11 Upper bevel part 12 Lower bevel part 13 Apex part 15 Resist film 20 Wafer support part 30 Alignment part 31 Transmission illumination part 32 Line sensor 40 Imaging part 41 Incident illumination part 42 Image sensor 50 Data processing Part (first and second detection part, calculation part, inspection part)

Claims (4)

An inspection method for inspecting the vicinity of an end of a disk-shaped substrate having a film that substantially covers one planar portion,
A first step of detecting an end position of the substrate;
A second step of imaging the vicinity of the end of the substrate including the end of the film at the end position of the substrate detected in the first step;
A third step of detecting an end position of the film from an image in the vicinity of the end of the substrate imaged in the second step;
From the edge position of the substrate and the edge position of the film detected in the first and third steps, respectively, between the edge of the substrate and the edge of the film along the radial direction of the substrate. A fourth step for determining the distance;
And a fifth step of inspecting whether there is an abnormality in the vicinity of the end portion of the substrate based on the distance between the end portion of the substrate and the end portion of the film obtained in the fourth step. A characteristic inspection method. In the first step, the end position of the substrate is detected over the entire circumference of the substrate while rotating the substrate,
In the second step, the vicinity of the edge of the substrate is imaged over the entire circumference of the substrate while rotating the substrate,
In the third step, detecting the end position of the film over the entire circumference of the substrate;
In the fourth step, the distance between the edge of the substrate and the edge of the film along the radial direction of the substrate over the entire circumference of the substrate is determined,
In the fifth step, based on the distance between the end portion of the substrate and the end portion of the film obtained over the entire circumference of the substrate, the presence or absence of an abnormality in the vicinity of the end portion of the substrate is inspected. The inspection method according to claim 1. An inspection apparatus for inspecting the vicinity of an end of a disk-shaped substrate having a film that substantially covers one planar portion,
A first detection unit for detecting an end position of the substrate;
An imaging unit that images the vicinity of the end of the substrate including the end of the film at the end position of the substrate detected by the first detection unit;
A second detection unit that detects an end position of the film from an image near the end of the substrate imaged by the imaging unit;
From the edge position of the substrate and the edge position of the film detected by the first and second detection units, between the edge of the substrate and the edge of the film along the radial direction of the substrate. An arithmetic unit for calculating the distance of
An inspection unit that inspects for the presence or absence of an abnormality in the vicinity of the end of the substrate based on the distance between the end of the substrate and the end of the film obtained by the arithmetic unit. Characteristic inspection device. A support portion for rotatably supporting the substrate;
The first detection unit detects the position of the end of the substrate over the entire circumference of the substrate while rotating the substrate by the support unit,
The imaging unit images the vicinity of the end of the substrate over the entire circumference of the substrate while rotating the substrate by the support unit,
The second detection unit detects an end position of the film over the entire circumference of the substrate,
The calculation unit obtains the distance between the end of the substrate and the end of the film along the radial direction of the substrate over the entire circumference of the substrate,
The inspection unit inspects whether there is an abnormality in the vicinity of the end portion of the substrate based on the distance between the end portion of the substrate and the end portion of the film obtained over the entire circumference of the substrate. The inspection apparatus according to claim 3.

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