JP2020197530A - Appearance inspection device - Google Patents

Abstract

To provide an appearance inspection device for detecting defects in a wafer before a polishing step is done, which is a wafer with a concavo-convex surface.SOLUTION: The present invention relates to an appearance inspection device 1 for detecting defects in a wafer W before a polishing step is done, which is a wafer with a concavo-convex surface. The appearance inspection device includes: holding means 131 for holding the wafer W; first illumination means 133 for irradiating a predetermined inspection region S-surface of the wafer W with a plurality of measurement lights from an oblique direction; second illumination means 134 arranged in a position which is more distant from the wafer W than the first illumination means 133 and has an angle of elevation from the wafer W larger than that of the first illumination means 133, the second illumination means irradiating the inspection region S-surface with measurement lights; and imaging means 135 having an optical axis which agrees with a virtual center axis A of the inspection region S, the imaging means imaging the inspection region S-surface.SELECTED DRAWING: Figure 2

Description

The present invention relates to a visual inspection apparatus having a plurality of irregularities on the surface and detecting defects in a wafer before a polishing step.

Generally, a wafer manufacturing method includes a plurality of surface flattening steps of a wafer in which an ingot such as single crystal silicon is cut (sliced) by a diamond blade or the like. The surface flattening step includes, for example, a wrapping step for eliminating irregularities on the wafer surface and making the in-plane thickness uniform by slicing, an etching step for removing machining damage on the wafer surface, and finally. There is a polishing process (polishing process) for finishing to the desired surface accuracy.

In the lapping step, both sides (front surface and back surface) of the cut wafer are roughly polished by a lapping process using, for example, a lapping agent such as an alumina abrasive. As a result, the front surface and the back surface of the wafer are arranged in parallel, and the wafer is processed to a predetermined thickness.

In the next etching step, both sides of the wafer are etched using a solution, gas, or the like. As a result, the unevenness formed on both sides of the wafer is reduced, and both sides of the wafer are flattened.

The polishing step may be divided into a primary polishing step of rough polishing and a secondary polishing step of precision polishing. In this case, in the primary polishing step, both sides of the wafer are roughly polished and hydrophilized using a polishing device, and in the secondary polishing step, both sides of the wafer are roughened using a polishing device as in the primary polishing step. Finely polish and finish in a mirror shape.

By the way, in the wafer manufacturing process, the appearance inspection device inspects the surface of the wafer for defects such as scratches, stains, scratches, pits (holes), and pinholes.

For example, in a conventional surface inspection system for a semiconductor wafer, the entire surface of the semiconductor wafer is irradiated with light from an oblique direction by a light source device, and the entire semiconductor wafer is photographed by a CCD camera (see, for example, Patent Document 1).

Further, the conventional wafer visual inspection apparatus has an incoherent light source that converges the incoherent light and irradiates the wafer surface obliquely from an azimuth group forming 45 degrees with respect to the dominant pattern line direction. An optical mask that blocks reflection of coherent light from pattern corners is installed in the imaging optical system (see, for example, Patent Document 2).

Further, in the conventional foreign matter inspection device, the wafer is obliquely illuminated by the inspection light irradiation device, and the scattered light of the inspection light on the wafer under the dark field is detected by the scattered light detector to identify the coordinate position of the foreign matter. The inspection device will be provided with an epi-illumination device and an imaging device. The coordinate position of the foreign matter identified by the foreign matter determination device based on the detection of the scattered photodetector is imaged by the imaging device under bright field illumination by the epi-illumination device, and the foreign matter image is extracted based on this imaging (for example, Patent Document). 3).

Japanese Unexamined Patent Publication No. 2011-203245 Japanese Unexamined Patent Publication No. 2003-185593 Patent No. 39382227

By the way, wafers having defects such as scratches on the surface are removed at a relatively early stage in the manufacturing process, and only non-defective products can be processed in the subsequent manufacturing process. Therefore, production efficiency and manufacturing cost are improved. It is superior in terms of aspects.

However, although the conventional visual inspection apparatus is useful for detecting defects (unevenness) on the mirror-like wafer surface after the polishing process, for example, the wafer surface has a plurality of irregularities after the etching process. In this state, there is a limit to detecting defects such as scratches in distinction from the unevenness.

The present invention has been made to solve the above problems, and even a wafer having a plurality of irregularities on the surface and before the polishing process is visually inspected to effectively detect defects such as scratches by distinguishing from the irregularities. It provides a device.

The visual inspection device according to the present invention is a visual inspection device that has a plurality of irregularities on the surface and detects defects in the wafer before the polishing step, and is a holding means for holding the wafer and a predetermined inspection region surface of the wafer. On the other hand, the first illuminating means that irradiates a plurality of measurement lights from an oblique direction and the position where the distance from the wafer is farther than that of the first illuminating means and the elevation angle from the wafer is larger than that of the first illuminating means. A second illumination means for irradiating the inspection area surface with measurement light, and an imaging means for imaging the inspection area surface with the optical axis coincident with the virtual central axis of the inspection area. And.

According to the present invention, it is possible to provide an appearance inspection apparatus that effectively detects defects such as scratches by distinguishing a wafer having a plurality of irregularities on the surface before the polishing step from the irregularities.

It is a device block diagram of the visual inspection apparatus which concerns on 1st Embodiment. It is a plan schematic diagram which shows the schematic structure of the appearance inspection apparatus which concerns on 1st Embodiment. It is a figure which shows the schematic structure of the surface inspection part which concerns on 1st Embodiment, (A) is a plan view, (B) is a front view. It is a schematic diagram which shows the irradiation intensity from the direct illumination part and the indirect illumination part which concerns on 1st Embodiment. It is a schematic diagram which shows the inspection area of the wafer which concerns on 1st Embodiment. It is a figure which shows the schematic structure of the edge inspection part which concerns on 1st Embodiment, (A) is a plan view, (B) is a front view. It is a schematic diagram which shows the edge part of the wafer which concerns on 1st Embodiment. It is a flowchart which shows the process of the appearance inspection apparatus which concerns on 1st Embodiment. It is a flowchart which shows the process of the edge inspection part which concerns on 1st Embodiment. It is a flowchart which shows the process of the surface inspection part which concerns on 1st Embodiment. It is a figure which shows the schematic structure of the surface inspection part which concerns on 2nd Embodiment, (A) is a plan view, (B) is a side view.

Here, the present invention can be implemented in many different forms. Therefore, it goes without saying that it should not be interpreted only by the description contents of the following embodiments.

[First Embodiment]
FIG. 1 is a device block diagram of the visual inspection device 1 according to the present embodiment.
As shown in FIG. 1, the visual inspection apparatus 1 is imaged by an inspection unit 100 that inspects at least defects on the front surface and / or back surface of the wafer, a transport unit 200 that transports the wafer to the inspection unit 100, and an inspection unit 100. An image display that displays the presence / absence and position of defects detected by the calculation unit 300 that detects defects such as scratches on the front and / back surfaces of the wafer based on the image, the storage unit 400 that stores image data, and the calculation unit 300. The input / output unit 500 is provided with an operation unit for performing a unit and a cursor operation on an image.
In the present invention, the appearance inspection device 1 may include at least a wafer inspection unit 100.

FIG. 2 is a schematic plan view showing a schematic configuration of the visual inspection device 1.
As shown in FIG. 2, the inspection unit 100 includes at least a back surface inspection unit 120 that inspects the back surface of the wafer W, and / or a surface inspection unit 130 that inspects the surface of the wafer W, and an edge that inspects the edge portion of the wafer W. It includes an inspection unit 110.

The transport unit 200 includes one or a plurality of storage units 210 in which the uninspected wafer W is stored, a defective product storage unit 220 in which the wafer W determined to be defective is stored, and an edge inspection from the storage unit 210. A transfer arm 230 that conveys the wafer W to the unit 110, an inversion arm 240 that conveys the wafer W from the edge inspection unit 110 to the back surface inspection unit 120, and an inversion arm that conveys the wafer W from the back surface inspection unit 120 to the front surface inspection unit 130. It has 250 and.

Here, the wafer W stored in each storage portion 210 has an uneven surface and is before the polishing process, and is a silicon wafer, silicon carbide (SiC), gallium arsenide (GaAs), gallium phosphorus (GaP). ), A semiconductor wafer of a compound wafer such as gallium nitride (GaN).

The transfer arm 230 grips the outer peripheral edge of the wafer W from the storage unit 210 in which one or more wafers W are aligned and stored, pulls out one wafer W, and pulls out the drawn wafer W from the edge inspection unit 110. It is placed on the holding portion 111. Further, the transfer arm 230 stores the wafer W determined to be a non-defective product after inspection by the edge inspection unit 110, the back surface inspection unit 120, and the front surface inspection unit 130 to the original position of the storage unit 210, while it is regarded as a defective product. The determined wafer W is stored in the defective product storage unit 220.

The reversing arm 240 includes a suction holding portion 241 that sucks and holds the wafer W, and a support portion 242 that supports the suction holding portion 241.
The suction holding portion 241 sucks and holds the wafer W from the back surface or the front surface side of the wafer W on the holding portion 111 whose edge portion has been inspected by the edge inspection portion 110 by a suction mechanism (not shown), and 180 with the support portion 242 as a base point. The wafer W is inverted by rotating the degree of rotation, and the inverted wafer W is placed on the holding portion 121 of the back surface inspection unit 120.

The reversing arm 250 includes a suction holding portion 251 that sucks and holds the wafer W, and a support portion 252 that supports the suction holding portion 251.
The suction holding unit 251 sucks and holds the wafer W from the back surface or the front surface side of the wafer W on the holding unit 121 whose back surface inspection has been completed in the back surface inspection unit 120 by a suction mechanism (not shown), and rotates 180 degrees with the support unit 252 as a base point. Then, the wafer W is inverted, and the inverted wafer W is placed on the holding portion 131 of the surface inspection portion 130.

Hereinafter, the front surface inspection unit 130, the back surface inspection unit 120, and the edge inspection unit 110 will be described in detail.

First, the surface inspection unit will be described with reference to FIGS. 2 and 3. Here, FIG. 3 is a plan view (A) and a front view (B) showing a schematic configuration of the surface inspection unit 130.
As shown in FIGS. 2 and 3, the surface inspection unit 130 holds the wafer W and inspects the holding portion 131 capable of rotating the held wafer W in the circumferential direction and the holding portion 131 from the reference position P5. It is provided with a transport rail 132 for moving to P6.

The holding portion 131 has a disk-shaped table 131a and a support column 131b that supports the table 131a.
The holding unit 131 may have a positioning mechanism such as a suction mechanism for stably holding the wafer W on the table 131a.

At the inspection position P6, the first illumination unit 133 that irradiates a plurality of measurement lights from an oblique direction with respect to the predetermined inspection area S of the wafer W, and the distance from the wafer W is larger than that of the first illumination unit 133. A second illumination unit 134, which is far away and has an elevation angle from the wafer W larger than that of the first illumination unit 133, and irradiates the inspection area S with measurement light, and an optical axis of the inspection area S. An imaging unit 135 (hereinafter, for convenience, referred to as a first imaging unit 135) that coincides with the virtual central axis A and images the inspection area S is provided.

The first illumination unit 133 irradiates the inspection region S with measurement light from two opposite directions with the virtual central axis A in between and two opposite directions orthogonal to the direction. At this time, for example, the inspection area S is in a state of being irradiated with the measurement light by irradiation from the first illumination unit 133a and the first illumination unit 133c.
Here, the virtual center axis A is a straight line that passes through the substantially center C (see FIG. 5) of the inspection area S and is orthogonal to the wafer W. The center C may be, for example, the center of gravity of the inspection area S, or may be a point where the distances from the opposite first illumination unit 133 are equal.

Although not shown, the first illumination unit 133 includes an LED (Light Emitting Diode) light source device, an optical fiber, a line light guide, and a condenser lens. The first illumination unit 133 (line light guide) is arranged so as to form four sides of a rectangle when viewed in a plan view. The condenser lens is, for example, a cylindrical lens.

The first illumination unit 133 passes the LED light incident on the incident side of the optical fiber from the LED light source device through a condenser lens from a line light guide in which the ends of the optical fibers on the exit side are arranged in a straight line, and a wafer. Irradiate the inspection area S of W. At this time, the focused width of the measured light to be irradiated is appropriately adjusted by the condenser lens according to the inspection area S.

The irradiation angle of the first illumination unit 133 with the center C as the apex with respect to the wafer W surface is preferably 10 to 30 degrees, for example, 15 degrees.
By irradiating the measurement light from the first illumination unit 133 at an irradiation angle within the above range, scratches and dirt on the surface of the wafer W can be highlighted.

Since the measurement light from the first illumination unit 133 is emitted from an oblique direction, it becomes dark field illumination. As a result, the direction dependence of illumination may become a problem in detecting defects on the surface of the wafer W. Therefore, as described above, the first illumination unit 133 irradiates the inspection region S with the measurement light from the four directions around the virtual central axis A to eliminate the direction dependence.

In the above, the configuration in which the first illumination unit 133 is provided with a linear line light guide or the like is shown, but the present invention is not limited to this, and it is sufficient that the inspection area S can be irradiated with the measurement light. For example, it may be a point light source.
Further, as the first illumination unit 133, an example in which the measurement light is irradiated from four directions around the virtual center axis is shown. However, for example, the measurement light may be irradiated from two orthogonal directions, or the virtual center may be irradiated. The measurement light may be irradiated from three directions with an interval of 120 degrees around the axis.

The second illumination unit 134 is located at a position where the distance from the wafer W is farther than that of the first illumination unit 133 and the elevation angle from the surface of the wafer W with the center C as the apex is larger than that of the first illumination unit 133. It is arranged. The second illumination unit 134 is arranged at a position not within the imaging field of view of the first imaging unit 135.

The irradiation angle of the second illumination unit 134 with the center C as the apex with respect to the wafer W surface (same plane) is preferably 10 to 40 degrees, more preferably 20 to 30 degrees.

The second illumination unit 134 is located at a position facing the inspection area S with the direct illumination unit 134a that directly irradiates the measurement light and the first imaging unit 135 described later with respect to the direct illumination unit 134a. It is provided with an indirect illumination unit 134b that is arranged and indirectly irradiates the inspection area S with measurement light.
In this case, the irradiation angle of the direct illumination unit 134a is, for example, 25 degrees.

In the direct illumination unit 134a and the indirect illumination unit 134b, a plurality of LED light sources are arranged side by side in a straight line, and the measurement light from the plurality of LED light sources is applied to the inspection area S.
The direct illumination unit 134a directly irradiates the inspection region S of the wafer W with divergent light as measurement light.

The indirect illumination unit 134b is arranged so that its optical axis is orthogonal to the optical axis of the first imaging unit 135, and emits divergent light (LED light source) as measurement light with respect to the inspection region S of the wafer W. It irradiates indirectly. The indirect illumination unit 134b directly irradiates the measurement light toward the cylindrical portion 135b of the first imaging unit 135, and irradiates the scattered light on the inspection region S of the wafer W. By using the cylindrical portion 135b of the first imaging unit 135, indirect illumination can be easily created without providing a separate mechanism.
The indirect lighting unit 134b is not limited to the above configuration, and may have any configuration as long as it can create indirect lighting.

FIG. 4 is a schematic view showing the irradiation intensity from the direct illumination unit and the indirect illumination unit.
Since the direct illumination unit 134a irradiates the inspection area S with the measurement light from an oblique direction, the irradiation intensity L1 with respect to the inspection area S is not uniform, and the irradiation intensity L1 increases as the distance from the direct illumination unit 134a increases. Becomes weaker. That is, in the inspection region S, the irradiation intensity L1 becomes weaker from the direct illumination unit 134a side toward the first imaging unit 135 side.
Therefore, in the present invention, in order to make the irradiation intensity with respect to the inspection region S uniform, the first imaging unit 135 is provided with respect to the first imaging unit 135 side where the irradiation intensity L1 is weak, that is, the direct illumination unit 134a. The indirect illumination unit 134b is arranged at a position facing the indirect illumination unit 134b, and the irradiation amount of the indirect scattered light from the indirect illumination unit 134b is supplemented to the inspection area S by the irradiation intensity L2 to make the irradiation intensity uniform.

Since the second illumination unit 134 is originally irradiated from an oblique direction, it is a dark field illumination. However, in the present invention, the wafer W before the polishing process having irregularities (pear-skin texture) on the surface is targeted for inspection. In addition, the amount of measurement light reflected toward the imaging unit 135 is large. As a result, it becomes possible to detect a defect different from the defect detected by the dark field illumination of the first illumination unit 133, and it is possible to detect a defect which was difficult to detect by the conventional inspection apparatus. In addition, the direction dependence is reduced.

The first imaging unit 135 includes a camera 135a and a cylindrical unit 135b in which a telecentric lens in which the main ray is parallel to the optical axis is provided, and as described above, from the indirect illumination unit 134b. Indirect illumination is created by directly irradiating the measurement light toward the cylindrical portion 135b.

FIG. 5 is a schematic view showing an inspection area S of the wafer W.
As shown in FIG. 5, the inspection area S is one of six divisions (inspection areas S1 to S6) of the surface of the wafer W. The surface inspection unit 130 moves the wafer W by a drive mechanism (not shown) to sequentially inspect the inspection areas S1 to S6. By dividing and inspecting the surface of the wafer W in this way, defects on the surface can be clearly captured even with a low-pixel camera, and the amount of measured light irradiation to one inspection area S is large. can do.
The number of divisions of the inspection area S is not particularly limited, and for example, one of the four divisions may be the inspection area S, or the entire surface of the wafer W may be the inspection area S.

The back surface inspection unit 120 has the same configuration as the front surface inspection unit 130, and although details are omitted, a holding unit 121 that holds the wafer W and can rotate the held wafer W in the circumferential direction, and the holding unit 121. First, the inspection position P4 is provided with a transport rail 122 for moving the light from the reference position P3 to the inspection position P4, and the inspection position P4 is irradiated with a plurality of measurement lights from an oblique direction with respect to a predetermined inspection area S of the wafer W. The illumination unit 123 is arranged at a position where the distance from the wafer W is farther than that of the first illumination unit 123 and the elevation angle from the wafer W is larger than that of the first illumination unit 123, and the measurement is performed with respect to the inspection area S. A second illumination unit 124 that irradiates light and a (first) imaging unit 125 whose optical axis coincides with the virtual central axis A of the inspection area S and images the inspection area S are arranged.

When the calculation unit 300 acquires the captured image data from the inspection unit 100 (first imaging units 125, 135), the calculation unit 300 detects a defect on the surface of the wafer W, and the image data after image processing reflecting the detected content is reflected. Is displayed on the image display unit of the input / output unit 500.
At this time, the calculation unit 300 collects the images of the inspection areas S1 to S6 of the wafer W into one, edits it as an image of one wafer W, and outputs the edited image data to the input / output unit 500. You may.

Further, the calculation unit 300 controls each illumination unit and the imaging unit independently, and enables dimming by each illumination.

Next, the edge inspection unit will be described with reference to FIGS. 2, 6 and 7. Here, FIG. 6 is a plan view (A) and a front view (B) showing a schematic configuration of the edge inspection unit 110, and FIG. 7 is a schematic view showing an edge portion of the wafer W.
As shown in FIGS. 2 and 6, the edge inspection unit 110 holds the wafer W and rotates the held wafer W in the circumferential direction. The holding unit 111 and the holding unit 111 are moved from the reference position P1 to the inspection position P2. It is provided with a transport rail 112 for moving to.

The holding portion 111 has a disk-shaped table 111a and a support column 111b that supports the table 111a.
The holding unit 111 may have a positioning mechanism such as a suction mechanism for stably holding the wafer W on the table 111a.

At the inspection position P2, a bevel inspection unit 113 for inspecting the bevel portion at the edge portion of the wafer W and an apex inspection unit 114 for inspecting the apex portion and the bevel portion at a position different from the bevel inspection unit 113 are arranged. ing.
The bevel inspection unit 113 and the apex inspection unit 114 can detect defects such as scratches and chipping that occur during polishing and wafer transfer.

As shown in FIG. 7, the bevel portion WB is a portion inclined toward the outer peripheral end portion of the wafer edge portion, and the apex portion WA is an outer peripheral end surface portion of the wafer W connected to the upper and lower bevel portions WB. Since the wafer W is before the polishing process, its surface has irregularities, but the edge portion is polished in order to suppress the occurrence of scratches and the like.

The bevel inspection unit 113 includes an annular illumination 115a that irradiates the bevel portion WB with measurement light from both sides (front and back surfaces) of the wafer W, and at least the upper and lower bevel portions WB whose optical axis is orthogonal to the central axis B of the wafer W. A surface illumination 115b that irradiates the measurement light, and a second imaging unit 116 whose optical axis coincides with the central axis of the annular illumination 115a and images the bevel portion WB are provided.
The bevel inspection unit 113 mainly irradiates the region WB2 on the surface side of the wafer W of the bevel portion WB with the measurement light, and the second imaging unit 116 images the region.
The bevel inspection unit 113 may not be provided with the surface illumination 115b.

In the annular illumination 115a, a plurality of LED light sources are arranged on an annular wiring board.
The central axis of the annular illumination 115a is parallel to the central axis B of the wafer W, and the bevel portion WB is irradiated with the measurement light from both sides (front surface and back surface) of the wafer W.

The surface illumination 115b has a substantially rectangular shape, and a plurality of LED light sources are arranged side by side in the vertical and horizontal directions. When the bevel inspection unit 114 is provided with the surface illumination 115b, the reflected light from the bevel unit WB can be sufficiently obtained, and a clearer captured image of the bevel unit WB can be obtained.

The second imaging unit 116 includes a camera 116a and a cylindrical unit 116b in which a telecentric lens in which the main ray is parallel to the optical axis is provided, and is arranged so as to face each other with the wafer W in between. (The optical axes of each imaging unit are the same).

The apex inspection unit 114 has a first surface illumination 117a whose optical axis is orthogonal to the central axis B of the wafer W and irradiates the apex unit WA with measurement light, and measurement light from the front and back surfaces of the wafer W to the apex unit WA. The second surface illumination 117b that illuminates the apex portion WA and the pseudo-coaxial epi-illumination 118 whose optical axis is orthogonal to the central axis B of the wafer W and irradiates the apex portion WA and the bevel portion WB with measurement light, and the optical axis is pseudo-coaxial epi-illumination It is provided with a third imaging unit 119 that matches the illumination 118 and images the apex unit WA and the bevel unit WB.
The pseudo-coaxial epi-illumination 118 mainly irradiates the surface region WA1 perpendicular to the surface of the wafer W in the apex portion WA with the measurement light, and the first surface illumination 117a mainly irradiates the wafer W in the apex portion WA. The measurement light is applied to the region WA2 that is inclined from the surface region perpendicular to the surface to the bevel portion WB. The second surface illumination 117b mainly irradiates the region WB1 on the apex WA side of the bevel portion WB with the measurement light.
An opening 117c is formed in the central portion of the first surface illumination 117a, and the measurement light from the pseudo coaxial epi-illumination 118 is irradiated to the apex portion WA through the opening 117c, and an image of the apex portion WA is displayed. The image is taken by the third imaging unit 119.
The apex inspection unit 114 may not be provided with the second surface illumination 117b.

The first surface illumination 117a has a substantially rectangular shape, and a plurality of LED light sources are arranged side by side in the vertical and horizontal directions. An opening 117c is formed in the central portion of the first surface illumination 117a.
In front of the first surface illumination 117a (wafer W side), a diffusion plate having an opening formed in the center thereof may be provided so as to face the first surface illumination 117a.

The second surface illumination 117b has a substantially rectangular shape, and a plurality of LED light sources are arranged side by side in the vertical and horizontal directions. When the apex inspection unit 114 is provided with the second surface illumination 117b, it is possible to sufficiently obtain the reflected light from the bent boundary portion between the apex portion WA and the bevel portion WB, and the apex portion WA and the apex portion WA which are clearer in a wider range can be obtained. An captured image of the bevel portion WB can be obtained.

The pseudo-coaxial epi-illumination 118 includes a surface illumination 118a and a beam splitter or half mirror 118b.
The measurement light emitted from the surface illumination 118a is reflected by the beam splitter 118b and is applied to the apex portion WA through the opening 117c of the first surface illumination 117a.

The reflected light reflected by the apex portion WA and the reflected light reflected by the measurement light from the first surface illumination 117a pass through the opening 117c of the first surface illumination 117a and pass through the beam splitter 118b, and then the third surface illumination 117a. The light is received by the imaging unit 119 of.

The third imaging unit 119 includes a camera 119a and a cylindrical unit 119b provided with a telecentric lens in which the main ray is parallel to the optical axis.

As described above, since the edge portion of the wafer W is polished, the apex portion WA is imaged by the third imaging unit 119 without interposing the irradiation light from the pseudo coaxial epi-illumination 118 in the apex portion WA. Then, the image of the edge portion of the opening 117c reflected by the apex portion WA is reflected in the captured image.
In the apex inspection unit 114 according to the present embodiment, since the apex unit WA is irradiated with the irradiation light from the pseudo coaxial epi-illumination 118 via the beam splitter 118b, it is reflected by the apex unit WA having a mirror surface shape. It is possible to suppress the image of the edge portion of the opening 117c from being reflected in the captured image.

The images captured by the second imaging unit 116 and the third imaging unit 119 are output to the calculation unit 300 and edited as a strip-shaped image by the calculation unit 300. The calculation unit 300 detects defects in the bevel unit WB and the apex unit WA, and displays the image data after image processing reflecting the detected contents on the image display unit of the input / output unit 500.

The visual inspection device 1 according to the present invention may include at least a front surface inspection unit 130 and / or a back surface inspection unit 120, and the edge inspection unit 110 is not essential.

Next, the processing operation of the visual inspection apparatus 1 according to the present embodiment will be described with reference to FIGS. 8 to 10. FIG. 8 is a flowchart showing the processing of the visual inspection apparatus according to the present invention, FIG. 9 is a flowchart showing the processing of the edge inspection unit, and FIG. 10 is a flowchart showing the processing of the surface inspection unit. Since the processing operation in the back surface inspection unit 120 is the same as the processing operation in the front surface inspection unit 130, the description thereof will be omitted.

As shown in FIG. 8, in the visual inspection device 1, when the storage unit 210 is thrown onto the vertical movement elevator (not shown), the vertical movement elevator has an edge at the position of the wafer W to be inspected in the storage unit 210. The storage unit 210 is moved in the vertical direction so as to match the height of the holding unit 111 of the inspection unit 110.
The transfer arm 230 pulls out one wafer W from the storage unit 210 and places the wafer W on the holding unit 111 waiting at the reference position P1 of the edge inspection unit 110 (step S100).

Next, the holding portion 111 moves to the inspection position P2 for inspecting the edge portion of the wafer W along the transport rail 112, and inspects the edge portion of the wafer W at the inspection position P2 (step S200).

As shown in FIG. 9, at the inspection position P2 of the edge inspection unit 110, the bevel unit WB is irradiated with the measurement light from the annular illumination 115a and the surface illumination 115b of the bevel inspection unit 113, while being different from the bevel inspection unit 113. At the position, the apex portion WA and the bevel portion WB are irradiated with the measurement light from the first surface illumination 117a, the second surface illumination 117b, and the pseudo coaxial epi-illumination 118 of the apex inspection unit 114 (step S210).

The second imaging unit 116 and the third imaging unit 119 image each region including the bevel portion WB and the apex portion WA of the wafer W in the imaging region (step S220), and output image data to the calculation unit 300 (step S220). Step S230).
The upper and lower bevel portions WB may be imaged simultaneously or individually.

When the imaging of the entire circumference of the outer peripheral edge of the wafer W has not been completed (step S240: NO), the holding unit 111 rotates by a predetermined angle to the next imaging region within a range that partially overlaps with the previous imaging region (step). S250), the second imaging unit 116 and the third imaging unit 119 image the region including the bevel portion WB and the apex portion WA of the new imaging region (next imaging region), and output the image data to the calculation unit 300. To do.

As described above, the holding unit 111 is sequentially rotated by a predetermined angle to the next imaging region, and the second imaging unit 116 and the third imaging unit 119 are in the new imaging region (next imaging region). When the region including the bevel portion WB and the apex portion WA is imaged, the image data is output to the calculation unit 300, and the imaging and image data output of the entire outer peripheral edge portion of the wafer W is completed (step S240: YES). , The edge inspection process of the wafer W is completed.

When the calculation unit 300 acquires the captured image data, the calculation unit 300 edits the edge portion of the wafer W as a strip-shaped image for each predetermined central angle of the wafer W, and outputs the edited image data after image processing to the input / output unit 500. And display the image.

When the edge inspection is completed at the inspection position P2, the holding portion 111 moves from the inspection position P2 to the reference position P1 along the transfer rail 112 while holding the wafer W.
The reversing arm 240 sucks and holds the wafer W from the back surface or the front surface side of the wafer W held by the holding portion 111 at the reference position P1, and rotates the suction holding portion 241 180 degrees with the support portion 242 as a base point to rotate the wafer W by 180 degrees. The wafer W that has been inverted and turned upside down is placed on the holding portion 121 that stands by at the reference position P3 of the back surface inspection unit 120 (step S300).

Next, the holding unit 121 moves to the inspection position P4 for inspecting the back surface of the wafer W along the transport rail 122, and inspects the back surface of the wafer W at the inspection position P4 (step S400).

When the back surface inspection is completed at the inspection position P4, the holding portion 121 moves from the inspection position P4 to the reference position P3 along the transport rail 122 while holding the wafer W.
The reversing arm 250 sucks and holds the wafer W from the back surface or the front surface side of the wafer W held by the holding portion 121 at the reference position P3, and rotates the suction holding portion 251 180 degrees with the support portion 252 as a base point to rotate the wafer W by 180 degrees. The wafer W that has been inverted and inverted on the front and back is placed on the holding unit 131 that stands by at the reference position P5 of the surface inspection unit 130 (step S500).

Next, the holding unit 131 moves along the transport rail 132 to the inspection position P6 for inspecting the surface of the wafer W, and inspects the surface of the wafer W at the inspection position P6 (step S600).

As shown in FIG. 10, at the inspection position P6 in the surface inspection unit 130, the inspection region S on the surface of the wafer W is irradiated with the measurement light from the first illumination unit 133 and the second illumination unit 134 (step S610). .. Here, the inspection area S for first irradiating the measurement light is the inspection area S1 at one of the six divisions (length 3 × width 2) of the wafer W (see FIG. 5).

The surface inspection unit 130 first irradiates the measurement light from one set of facing lights (for example, the first lighting units 133a and 133c) of the first lighting unit 133, and then irradiates the remaining one set of facing lighting. (For example, the first illumination units 133b and 133d) irradiate the measurement light, and finally, the second illumination unit 134 irradiates the measurement light.

The first imaging unit 135 receives the reflected light from the inspection region S1 for each irradiation, images the region including the inspection region S1 on the surface of the wafer W in the imaging region (step S620), and displays an image on the calculation unit 300. Output the data (step S630).

Next, the holding unit 131 is moved in the −Y direction by a drive mechanism (not shown), and the inspection areas S2 and S3 are sequentially moved into the imaging region of the first imaging unit 135 in the same manner as the inspection region S1. The region including the inspection regions S2 and S3 on the surface of the wafer W in the imaging region is imaged, and the image data is output to the calculation unit 300.
When the inspection of the inspection area S3 is completed, the holding unit 131 rotates 180 degrees around the central axis B, and the first imaging unit 135 images the area including the inspection area S4 in the same manner as the inspection areas S1 to S3. .. Subsequently, the holding unit 131 is moved in the −Y direction by a drive mechanism (not shown), and in the same manner as the inspection area S1, the first imaging unit 135 sequentially images the area including the inspection areas S5 and S6. Image data is output to the calculation unit 300 (step S640).

As described above, the first imaging unit 135 images the entire surface of the wafer W and ends the surface inspection process of the wafer W.

When the calculation unit 300 acquires the captured image data from the inspection unit 100 (first imaging units 125, 135), the calculation unit 300 detects a defect on the surface of the wafer W, and the image data after image processing reflecting the detected content is reflected. Is displayed on the image display unit of the input / output unit 500.

When the surface inspection is completed at the inspection position P6, the holding portion 131 moves from the inspection position P6 to the reference position P5 along the transfer rail 132 while holding the wafer W.
When the wafer W for which the inspection of the edge portion, the front surface and the back surface has been inspected is determined by the calculation unit 300 to be a non-defective product (step S700: YES), the transfer arm 230 holds the wafer W from the holding unit 131 to the storage unit 210. When the wafer W is stored in the original position (step S800) and is determined to be defective by the calculation unit 300 (step S700: NO), the wafer W is stored in the defective product storage unit 220 (step S900), and the wafer W is stored. The visual inspection process of is completed.
The non-defective product of the wafer W may be determined even after the edge inspection (step S200) and / or the back surface inspection (step S400). If a defective product is determined here, the subsequent inspection step is omitted. The wafer W determined to be a defective product may be stored in the defective product storage unit 220.

Subsequently, the vertical movement elevator moves the storage unit 210 in the vertical direction so that the position of the wafer W to be inspected next in the storage unit 210 matches the height of the holding unit 111, and is the same as the above-mentioned processing operation. In addition, the same visual inspection is continuously performed on all the wafers W in the storage unit 210.

When the appearance inspection device 1 completes the appearance inspection of all the wafers W in the storage unit 210, the calculation unit 300 outputs the inspection result to the input / output unit 500, and the input / output unit 500 detects the defect in the wafer W. Number (if necessary, the image of the wafer W after image processing) is displayed.

As described above, the visual inspection apparatus 1 inspects the front and back surfaces of the wafer W and the edge portion for defects.

[Second Embodiment]
The visual inspection apparatus according to this embodiment will be described with reference to FIG. 11A and 11B are views showing a schematic configuration of a surface inspection unit according to the present embodiment, where FIG. 11A is a plan view and FIG. 11B is a side view.
In this embodiment, the description overlapping with the first embodiment will be omitted.

As shown in FIG. 11, at the inspection position P6 of the surface inspection unit 130, the first illumination unit 136 that irradiates the predetermined inspection region S of the wafer W with the measurement light from an oblique direction, and the wafer W A second illumination unit that is arranged at a position where the distance is farther than the first illumination unit 136 and the elevation angle from the wafer W is larger than the first illumination unit 136, and irradiates the inspection area S with the measurement light. 134 and a third illumination unit 137, and an imaging unit 135 (first imaging unit 135) whose optical axis coincides with the virtual central axis A of the inspection area S and images the inspection area S are arranged. ..

Hereinafter, the first lighting unit 136 and the third lighting unit 137 will be described. Since the second illumination unit 134 and the first imaging unit 135 have the same configuration as that of the first embodiment, the description thereof will be omitted.

The first illumination unit 136 is illumination for detecting scratches or the like on the surface of the wafer W as in the case of the first embodiment, and its optical axis coincides with the virtual central axis A of the inspection area S for inspection. It is an annular illumination that irradiates the region S with the measurement light. By using the annular illumination, it is possible to irradiate the inspection area S with the measurement light without causing more uneven irradiation with one illumination.
In the first illumination unit (annular illumination) 136, a plurality of LED light sources are arranged on an annular wiring board.

Further, from the viewpoint of further reducing the illumination unevenness of the wafer W with respect to the inspection region S, the arrangement position (height) of the first illumination unit 136 is 5 to 15 mm from the wafer W, for example, 12 mm. Further, the first illumination unit 136 may be provided with a diffuser plate on the wafer W side, or a plurality of annular illuminations may be stacked vertically.

The third illumination unit 137 (137a, 137b) is arranged at a position where the distance from the wafer W is farther than that of the first illumination unit 136 and the elevation angle from the wafer W is larger than that of the first illumination unit 136. In addition, the measurement light is arranged in two opposite directions orthogonal to the arrangement direction of the second lighting means 134 arranged so as to face each other with the virtual central axis A of the inspection area S in between. Irradiate.

The third illumination units 137a and 137b are provided so as to be inclined with respect to the surface of the wafer W, and the inclination angle thereof is 60 to 80 degrees with respect to the virtual central axis A of the wafer W, for example, 70 degrees (wafer). It is 10 to 30 degrees with respect to the W surface, for example, 20 degrees).

The third illumination unit 137 can detect dirt, foreign matter, and the like adhering to the surface of the wafer W, which cannot be detected by the first illumination unit 136 and the second illumination unit 134.

Although not shown, the third illumination unit 137 includes an LED (Light Emitting Diode) light source device, an optical fiber, a line light guide, and a condenser lens. The condenser lens is, for example, a cylindrical lens.
The third illumination unit 137 passes the LED light incident on the incident side of the optical fiber from the LED light source device through the condenser lens from the line light guide in which the ends of the optical fiber on the exit side are arranged in a straight line, and the wafer. Irradiate the inspection area S of W. At this time, the focused width of the measured light to be irradiated is appropriately adjusted by the condenser lens according to the inspection area S.

Further, the third illumination unit 137 is arranged so that its longitudinal direction is the same. This prevents halation on the surface of the wafer W and makes it easier to detect scratches and dirt.

Next, the processing operation of the surface inspection unit 130 in the visual inspection apparatus 1 according to the present embodiment will be described (see FIG. 10). Since the processing operation in the back surface inspection unit 120 is the same as the processing operation in the front surface inspection unit 130, the description thereof will be omitted.

At the inspection position P6 in the surface inspection unit 130, the measurement light is irradiated from the first illumination unit 136, the second illumination unit 134, and the third illumination unit 137 to the entire surface of the inspection area S on the wafer W surface (step S610). ). Here, the inspection area S for first irradiating the measurement light is the inspection area S1 at one of the six divisions (length 3 × width 2) of the wafer W (see FIG. 5).

The surface inspection unit 130 first irradiates the measurement light from the annular illumination which is the first illumination unit 136, then irradiates the measurement light from the second illumination unit 134, and finally irradiates the measurement light from the third illumination unit 137. The measurement light is irradiated from (137a, 137b).

The first imaging unit 135 receives the reflected light from the inspection region S1 for each irradiation, images the region including the inspection region S1 on the surface of the wafer W in the imaging region (step S620), and displays an image on the calculation unit 300. Output the data (step S630).

As described above, the visual inspection apparatus 1 inspects the front and back surfaces of the wafer W for defects.

In each of the above embodiments, the inspection unit 100 has the edge inspection unit 110, the back surface inspection unit 120, and the front surface inspection unit 130. However, for example, the back surface inspection unit 120 and the front surface inspection unit 130 are unified. It may also be used as a front and back inspection unit. In this case, the wafer W reversing mechanism is arranged at the front and back inspection positions.

1 Visual inspection device 100 Inspection unit 110 Edge inspection unit 111 Holding unit 111a Table 111b Strut 112 Transport rail 113 Bevel inspection unit 114 Apex inspection unit 115a Circular lighting 115b Surface lighting 116 Second imaging unit 116a Camera 116b Cylindrical unit 117a First Surface illumination 117b Second surface illumination 117c Opening 118 Pseudo-coaxial epi-illumination 118a Surface illumination 118b Beam splitter or half mirror 119 Third imaging unit 119a Camera 119b Cylindrical unit 120 Back surface inspection unit 130 Surface inspection unit 121, 131 Holding unit 131a Table 131b Supports 122, 132 Transport rails 123, 133, 133a to 133d, 136 First lighting unit 124, 134 Second lighting unit 134a Direct lighting unit 134b Indirect lighting unit 125, 135 (first) imaging unit 135a Camera 135b Cylindrical part 137, 137a, 137b Third lighting part 200 Conveying part 210 Storage part 220 Defective product storage part 230 Conveying arm 240, 250 Reversing arm 241, 251 Suction holding part 242, 252 Support part 300 Calculation unit 400 Storage unit 500 Input / output unit A Virtual center axis C Center L1, L2 Irradiation intensity P1, P3, P5 Reference position P2, P4, P6 Inspection position S, S1 to S6 Inspection area W Wafer WA Apex part WA1, WA2 area WB Bevel part WB1, WB2 region

Claims (10)

A visual inspection device that detects defects in a wafer before the polishing process and has a plurality of irregularities on the surface.
A holding means for holding the wafer and
A first lighting means for irradiating a predetermined inspection area surface of the wafer with a plurality of measurement lights from an oblique direction,
The distance from the wafer is farther than that of the first lighting means, and the elevation angle from the wafer is larger than that of the first lighting means, and the inspection area surface is irradiated with the measurement light. The second lighting means and
A visual inspection apparatus characterized in that an optical axis coincides with a virtual central axis of the inspection region and includes an imaging means for imaging the surface of the inspection region. The second illuminating means is arranged at a position facing the direct illuminating means that directly irradiates the inspection area surface with the measurement light and the imaging means with the direct illuminating means, and the inspection. The visual inspection apparatus according to claim 1, further comprising an indirect lighting means for indirectly irradiating a region surface with measurement light. The second aspect of the present invention, wherein the indirect lighting means is arranged so that its optical axis is orthogonal to the optical axis of the image pickup means, and directly irradiates the measurement light toward the image pickup means. Visual inspection equipment. The first illumination means according to claim 2 or 3, wherein the first illumination means is an annular illumination whose optical axis coincides with the virtual central axis of the inspection area surface and irradiates the inspection area surface with measurement light. Visual inspection equipment. The distance from the wafer is farther than that of the first lighting means, and the elevation angle from the wafer is larger than that of the first lighting means, and the inspection area surface is irradiated with the measurement light. Equipped with a third lighting means
4. A fourth aspect of the present invention, wherein the third lighting means is arranged in two opposite directions orthogonal to the arrangement direction of the second lighting means, which are arranged so as to face each other with the virtual central axis interposed therebetween. The visual inspection device described in. Claims 1 to 1, wherein the first illuminating means irradiates the inspection area surface with measurement light from two opposite directions with the virtual central axis interposed therebetween and two opposite directions orthogonal to the direction. The visual inspection apparatus according to any one of 3. A bevel inspection means for inspecting the bevel portion of the wafer is provided, and the bevel inspection means irradiates the bevel portion of the wafer with measurement light from at least one side of the front surface side and the back surface side of the wafer, and an optical axis. The visual inspection apparatus according to any one of claims 1 to 6, wherein is provided as a second imaging means for imaging the bevel portion, which coincides with the central axis of the annular illumination. The visual inspection apparatus according to claim 7, wherein the bevel inspection means includes surface illumination whose optical axis is orthogonal to the central axis of the wafer and irradiates at least the upper and lower bevel portions with measurement light. .. The apex inspection means for inspecting the apex portion of the wafer is provided, and the apex inspection means has a first surface illumination and pseudo-coaxial epi-illumination in which the optical axis is orthogonal to the central axis of the wafer and the apex portion is irradiated with measurement light. It has an illumination and a third imaging means whose optical axis coincides with the pseudo-coaxial epi-illumination and images the apex portion and the bevel portion, and an opening is formed in the central portion of the first surface illumination. The visual inspection apparatus according to any one of claims 1 to 8, wherein the measurement light from the pseudo-coaxial epi-illumination is applied to the apex portion through the opening. The appearance according to claim 9, wherein the apex inspection means has a second surface illumination that irradiates the apex portion and the bevel portion with measurement light from at least one side of the front surface side and the back surface side of the wafer. Inspection equipment.

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