JP3099235B2 - Wafer inspection equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for transferring a wafer and a wafer inspection apparatus, and more particularly to a wafer inspection apparatus for inspecting electrical characteristics of a large number of electric element circuits formed on the surface of a semiconductor wafer, and this wafer inspection apparatus. The present invention relates to a method of transporting a wafer to be inspected, which is adapted to the apparatus, and an apparatus therefor.

[0002]

2. Description of the Related Art A semiconductor wafer has a large number of identical electric element circuits formed on its surface. Before cutting the electric element circuits into individual chips, a wafer prober is used to inspect the formation quality of each electric element circuit. Is determined for each electric element circuit by a wafer inspection apparatus referred to as "electric circuit".

The wafer inspection apparatus includes a cassette stock unit, a wafer take-out unit, a wafer transfer unit, an inspection table, a wafer inspection unit, and the like. A cassette accommodating a large number of wafers to be inspected is attached to the cassette stock unit. The wafers are sent out from the cassette to the wafer transfer unit one by one by the wafer unloading unit, and then are transferred by the wafer transfer unit. It is transported to the inspection table.

The wafer transfer section includes a conveyor section and a suction transfer section. The conveyor section transfers wafers from the cassette to a suction position of the suction transfer section. Then, after the center of the wafer located at the suction position is suction-held by the suction transfer unit, the wafer is transferred to the inspection table. The inspection table suction-holds the wafer transferred by the suction transfer unit, and performs horizontal movement in the X-Y direction and vertical movement in the Z direction according to the element arrangement at the time of element inspection.

[0005] The wafer inspection section comprises a probe stage, a tester and the like. A probe card corresponding to the wafer to be inspected is attached to the probe stage, and each electrode pad of the electric element circuit is brought into contact with a probe needle provided on the probe card to form each electric element circuit. The quality is sequentially inspected and determined by the tester.

[0006] After the inspection, the wafer is marked with an electrical element circuit determined to be defective, and then unloaded from the inspection table to the cassette by the suction transfer unit and the conveyor unit of the wafer transfer unit, and the cassette is unloaded. Returned to the original shelf.

[0007]

In the conventional wafer inspection apparatus, the transfer, inspection, and unloading can be automatically performed as described above if the wafer to be inspected has a fixed shape. However, if the wafer is a broken wafer, the wafer loses its balance and drops off from the conveyor unit during the transfer by the conveyor unit, or the wafer loses its balance and drops from the suction transfer unit during the transfer by the suction transfer unit. There is a fear that.

Therefore, conventionally, when inspecting the broken wafer, an operator places the wafers one by one on an inspection table and removes the inspected wafer from the inspection table. . The present invention has been made in view of such circumstances, and an object of the present invention is to provide a wafer transfer method and apparatus capable of automatically performing transfer, inspection, and unloading of a broken wafer, and an apparatus thereof, and a wafer inspection apparatus. I do.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a tray storage section in which a plurality of trays on which wafers are placed one by one are stored, and the tray storage section stores the trays in the tray storage section. A tray taking-out means for taking out the trays on which the wafers are placed one by one from the tray accommodating section, a photographing means for taking an image of the outer shape of the wafer on the tray taken out by the tray taking-out means, Image processing means for performing image processing of a video signal indicating the outer shape of the wafer to detect the center of gravity of the wafer, and outputting an outer shape signal of the wafer; and processing the image signal of the wafer detected by the image processing means. A first transfer unit for transferring the wafer by taking out the wafer from the tray while holding the center of gravity by suction and transferring the wafer to the wafer inspection unit; and holding the wafer carried by the wafer inspection unit by suction. An inspection table, an alignment means for aligning the wafer sucked and held on the inspection table, and a wafer aligned by the alignment means, based on a wafer outer shape signal output from the image processing means. Probe means for inspecting the wafer along the outer shape, second conveying means for transferring the wafer to the tray by sucking and conveying the center of gravity of the wafer which has been inspected by the probe means, and second conveying the wafer Tray storage means for storing the tray on which the wafers are placed by the means in the tray storage section.

[0010]

[0011]

[0012]

According to the present invention, the outer shape of the wafer is imaged by the photographing means, and a video signal indicating the outer shape of the wafer output from the photographing means is image-processed by the image processing means to detect the center of gravity of the wafer. . The center of gravity is suction-held by the wafer transfer means to transfer the wafer. Thus, even if the wafer is broken, the balance is not lost during the transfer, and the wafer can be smoothly transferred without falling.

According to the wafer inspection apparatus of the present invention,
The trays stored in the tray storage section are taken out one by one from the tray storage section together with the wafers by the tray take-out means. Next, the outer shape of the wafer on the taken-out tray is imaged by the photographing means, and a video signal indicating the outer shape of the wafer output from the photographing means is image-processed by the image processing means to detect the center of gravity of the wafer. . Then, the center of gravity is suction-held by the first transfer means for the wafer, the wafer is taken out of the tray, transferred to the wafer inspection unit, and suction-held by the inspection table. Then, after aligning the wafer on the inspection table by the alignment means, the wafer is inspected along the outer shape of the wafer based on the outer shape signal of the wafer output from the image processing means. Then, the portion of the center of gravity of the inspected wafer is suction-held by the second transfer means for the wafer, transferred, and returned to the tray. Then, the tray on which the wafer is placed is stored in the tray storage section by the tray storage means.

Further, the probe means performs inspection with the center of gravity of the wafer as a starting point.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a wafer transfer method and apparatus and a wafer inspection apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a perspective view showing an embodiment of a wafer transfer method according to the present invention and a wafer inspection apparatus 10 to which the apparatus is applied.

The wafer inspection apparatus 10 includes a cassette stock unit 12, a load pusher 14, a transport belt 16,
Tray guide 18, tray rotation chuck 20, shape recognition camera 22, pre-alignment camera 24, wafer suction collet 26, transfer arm 28, inspection table 30, inspection unit 32, unload arm 34, unload chuck 36, And an unload pusher 38.

The cassette stock unit 12 has an elevator mechanism (not shown), and a cassette 42 is mounted on a plate 40 which moves up and down by the operation of the elevator mechanism. As shown in FIG.
A plurality of trays 44 on which cracked wafers 46 are placed one by one are stored. A large number of electric element circuits 47 are formed on the surface of the cracked wafer 46.

The tray 44 is formed in a disk shape and has a ridge 48 formed on the periphery thereof to form a broken wafer 46.
Is prevented from dropping from the tray 44. Further, a rubber sheet material 50 is spread on the surface of the tray 44 to prevent the broken wafer 46 from slipping on the tray 44. Further, an opening 52 to be described later is formed in the center of the tray 44.

The load pusher 14 is provided so as to be reciprocally movable in the direction of the arrow in FIG. 1, and when driven toward the cassette 42, the loader pushes the tray 44 stored on a predetermined shelf of the cassette 42 together with the wafer 46 into the cassette. It can be extruded from 42 onto the conveyor belts 16, 16. As shown in FIG. 3, the transport belts 16 are arranged at intervals such that the tray 44 does not fall off the belt 16 during transport, and are driven in the transport direction indicated by the arrow in FIG. It can be transported toward the guide 18. The transport belts 16, 16 can be unloaded from the tray 44 toward the cassette 42 by being driven in the direction opposite to the transport direction described above, that is, in the unload direction.

The tray guide 18 is formed with an arcuate guide portion 54 facing the direction in which the tray 44 is conveyed.
The guide portion 54 is formed such that its curvature is equal to the outer peripheral curvature of the tray 44 and the center of curvature is located on the transport center line 56 of the transport belts 16, 16. The tray rotation chuck 20 includes:
It is provided so as to be able to move up and down in a space below the tray 44 in contact with the tray guide 18. Further, the tray rotating chuck 20 can rotate the tray 44 in the directions indicated by arrows A and B in FIG.

As shown in FIG. 1, the shape recognizing camera 22 can take an entire image of the tray 44 and the broken wafer 46 which are in contact with the tray guide 18. Further, the shape recognition camera 22 is connected to an image processing device (not shown) provided in the wafer inspection device 10.
This image processing apparatus binarizes the video signals of the tray 44 and the cracked wafer 46 output from the shape recognition camera 22 to detect the outer shape of only the cracked wafer 46 and calculates the area of the cracked wafer 46. can do. Then, the image processing apparatus detects the center of gravity 58 of the cracked wafer 46 based on the area of the cracked wafer 46, and
A drive signal is output to a motor that rotates the tray rotation chuck 20 so that 8 is positioned on the transport center line 56 as shown in FIG. Further, the image processing apparatus outputs an external shape signal of the broken wafer 46 to an inspection unit 32 described later.

The pre-alignment camera 24 includes a broken wafer 46 whose center of gravity 58 is located on the transfer center line 56.
, One of the electric element circuits 47, 47... Is imaged at a high magnification and pre-alignment is performed. As shown in FIG. 1, the wafer suction collet 26 is provided at the tip of the transfer arm 28 so as to be vertically movable.
After being moved above the broken wafer 46 by the transfer arm 28, the wafer suction collet 26 can be lowered to hold the center of gravity 58 by suction.
Further, the transfer arm 28 can move the wafer suction collet 26 holding the center of gravity 58 by suction onto the inspection table 30 as shown in FIG.

The inspection table 30 is provided on an XYZ moving mechanism 60, and the XYZ moving mechanism 60
, And is moved up and down in the Z direction. In addition, a suction port 62 for vacuum-sucking the wafer 46 is opened at the center of the inspection table 30, and the wafer 4 vacuum-sucked in the suction port 62.
Rod 6 for pushing up 6 from inspection table 30
4 is provided to be able to move up and down.

The wafer inspection section 32 has a microscope 66 as shown in FIG. 1, and a probe stage 68 is formed below the microscope 66. A probe card (not shown) corresponding to the cracked wafer 46 is attached to the probe stage 68. At the end of the unload arm 34, a wafer suction collet 70 is provided.
The wafer suction collet 70 is mounted on the unload arm 34.
After being moved above the cracked wafer 46 sucked by the inspection table 30, the portion of the center of gravity 58 can be sucked and held. In addition, the unload arm 3
4, the unload chuck 36 holds the wafer suction collet 70 holding the center of gravity 58 by suction, as shown in FIG.
Can move upwards.

The unload chuck 36 is provided with a hollow suction rod 72 so as to be extendable and contractible. This rod 7
2 can suck and hold the lower surface of the broken wafer 46 sucked by the wafer suction collet 70 through the opening 52 of the tray 44 when raised. As shown in FIG. 1, the unload pusher 38 can push the tray 44 unloaded from the position of the unload chuck 36 into the original shelf of the cassette 42 by the conveyor belts 16.

Next, the operation of the wafer inspection apparatus 10 configured as described above will be described. First, the load pusher 14 shown in FIG.
The tray 44 stored on a predetermined shelf of the cassette 42 is moved from the cassette 42 together with the broken
Extrude on 6. Next, the tray 44 is transported toward the tray guide 18 by the transport belts 16, 16. At this time, since the cracked wafer 46 is placed on the tray 44,
During transport, the balance is not lost and does not fall off from the transport belts 16, 16. When the tray 44 is pressed against the guide portion 54 of the tray guide 18, the tray 44 is moved so that the center 44 A of the tray 44 is positioned on the transport center line 56 of the transport belts 16, 16 by the guide portion 54. It is centered (see FIG. 3).

Next, after raising the tray rotating chuck 20 shown in FIG. 1 to hold the lower surface of the tray 44 by suction, the broken wafer 46 on the tray 44 is imaged by the shape recognition camera 22. A video signal indicating the outer shape of the broken wafer 46 is image-processed by an image processing device to detect a center of gravity 58 of the broken wafer 46, and the tray rotation chuck is positioned so that the center of gravity 58 is located on the transport center line 56. 20 is rotated (see FIG. 4).

Then, the electric element circuit 47 of the broken wafer 46 is imaged at a high magnification by the pre-alignment camera 24 to perform one-screen pre-alignment. Then, after the wafer suction collet 26 is moved above the broken wafer 46 by the transfer arm 28, it is lowered to suction-hold the portion of the center of gravity 58. Then, the wafer suction collet 26 holding the center of gravity 58 by suction is transferred to the transfer arm 28.
To move the cracked wafer 46 into the inspection table 30
It is transported upward (see FIG. 5). Cracked wafer 46 during transport
Since the center of gravity 58 is held by suction, the balance is not lost and does not drop from the wafer suction collet 26. When a vacuum sensor (not shown) detects that the cracked wafer 46 is not attracted to the inspection table 30 due to the warpage of the cracked wafer 46, the inspection table 30 is moved by the XYZ moving mechanism 60. Be raised. As a result, the cracked wafer 46 is reliably sucked onto the inspection table 30 by being sandwiched between the wafer suction collet 26 and the inspection table 30 (see FIG. 6).

Next, the inspection table 30 is stored in the XYZ
After being moved below the inspection section 32 by the moving mechanism 60 and measuring the thickness of the cracked wafer 44 at one point by a capacitance sensor (not shown), fine alignment is performed based on the shape recognition data captured by the shape recognition camera 22. Do. Then, by moving the inspection table 30 by the XYZ moving mechanism 60, the electric element circuits 47 of the broken wafer 46 are sequentially inspected.

As shown in FIG. 8, the inspection direction starts at the position of the center of gravity 58 of the cracked wafer 46 along the contour of the cracked wafer 46 based on the contour shape signal of the cracked wafer 46 output from the image processing apparatus. In the figure, the lower half is inspected in the direction of arrow A, and the upper half is inspected in the direction of arrow B. Also,
The inspection may be performed while detecting the edge of the cracked wafer 44 by the edge sensor. Thus, the electric element circuits 47, 47,... Of the cracked wafer 46 can be inspected efficiently.

After the inspection is completed, the inspection table 30 is
-Another area marker unit 74 by the YZ moving mechanism 60
Then, the electric element circuit 47 determined to be defective is marked. When the marking process is completed, the rod 64 provided on the inspection table 30 is raised as shown in FIG. 9 to push up the cracked wafer 46 from the inspection table 30, and the wafer suction collet 70
Of the center of gravity 58 of the unload arm 34
The cracked wafer 46 is moved by the unload chuck 36
Unload above.

Above the unload chuck 36, a toilet 44 centered by the tray guide 18 is transported in advance from the position of the tray guide 18. Then, the rod 72 of the unload chuck 36 is extended through the opening 52 of the tray 44 to hold the lower surface of the wafer 46 by suction. Then, the rod 72 is shrunk to break the broken wafer 46.
Is placed on the tray 44. Thus, the broken wafer 46 can be reliably placed on the tray 44 regardless of the size of the broken wafer 46.

Then, after unloading the tray 44 from the position of the unload chuck 36 to the position of the unload pusher 38, the unload pusher 38 is driven to push the tray 44 into the original shelf of the cassette 42. Thus, the transport, inspection, and unloading of the broken wafer 46 are completed. When another cracked wafer 46 is to be inspected, the above-described steps may be continued.

Therefore, in the present embodiment, the center of gravity 58 of the cracked wafer 46 is detected, and the portion of the center of gravity 58 is suctioned and held, transported, inspected, and unloaded. Also in the case of 46, it is possible to carry, inspect, and unload fully automatically.

[0035]

As described above, according to the wafer transfer method and apparatus according to the present invention, the outer shape of a wafer is imaged, and a video signal indicating the outer shape of the wafer is subjected to image processing to determine the center of gravity of the wafer. Since the wafer is conveyed while the center of gravity is detected and held by the wafer adsorbing / conveying means, the balance is not lost during the conveyance of a broken wafer. Thus, even a broken wafer can be smoothly transferred.

According to the wafer inspection apparatus of the present invention, the outer shape of the wafer is imaged by the photographing means, and a video signal indicating the outer shape of the wafer is processed by the image processing means to detect the center of gravity of the wafer. Then, the center of gravity was suction-held and transported to the inspection section, and the center of gravity of the inspected wafer was suction-held and unloaded.
Transfer, inspection, and unloading of broken wafers can be performed automatically. Further, since the broken wafer is placed on the tray, the wafer can be reliably placed on the tray regardless of the size of the wafer.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a wafer inspection apparatus according to the present invention.

FIG. 2 is a perspective view of a tray on which cracked wafers are placed.

FIG. 3 is a plan view showing a state where the tray is in contact with a tray guide and is centered;

FIG. 4 is a plan view showing a state in which the tray is rotated and the center of gravity of the broken wafer is positioned.

FIG. 5 is a sectional view showing a state in which a cracked wafer is placed on an inspection table.

FIG. 6 is a cross-sectional view showing a state where a cracked wafer is sucked by raising the inspection table.

FIG. 7 is a cross-sectional view showing a state where a cracked wafer after inspection has been placed on a tray.

FIG. 8 is an explanatory view showing an inspection direction of an electric element circuit of a cracked wafer.

FIG. 9 is a cross-sectional view showing a state where a wafer on an inspection table is pushed up by pins.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Wafer inspection apparatus 12 ... Cassette stock part 14 ... Load pusher 16 ... Transport belt 18 ... Tray guide 20 ... Tray rotation chuck 22 ... Shape recognition camera 24 ... Pre-alignment camera 26 ... Wafer suction collet 28 ... Transport arm 30 ... Inspection table 32 ... Inspection unit 34 ... Unload arm 36 ... Unload chuck 38 ... Unload pusher 44 ... Tray 46 ... Cracked wafer 58 ... Central center of cracked wafer

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/66 G01B 11/00 G01R 31/28 H01L 21/68

Claims (2)

(57) [Claims] 1. A tray storage unit in which a plurality of trays on which wafers are loaded one by one are stored, and one tray stored in the tray storage unit on which the wafers are mounted is one from the tray storage unit. Tray taking out means for taking out each one; photographing means for taking an image of the outer shape of the wafer on the tray taken out by the tray taking out means; and image processing of a video signal indicating the outer shape of the wafer outputted from the photographing means. Image processing means for detecting the center of gravity of the wafer and outputting an external shape signal of the wafer; and picking up and holding the center of gravity of the wafer detected by the image processing means to take out the wafer from the tray. A first transfer unit for transferring a wafer transferred to the wafer inspection unit, an inspection table for holding the wafer transferred to the wafer inspection unit by suction; An alignment unit for aligning the held wafer; and a wafer aligned by the alignment unit,
A probe means for inspecting the contour of the wafer based on a contour signal of the wafer output from the image processing means; and Of the wafer to be returned to the second
And a tray storage unit for storing the tray on which the wafer is placed by the second transfer unit for the wafer in the tray storage unit. 2. The wafer inspection apparatus according to claim 1, wherein said probe means performs inspection using a center of gravity of said wafer as a starting point.