JP2014154708A - Method and device for detecting crack of wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device capable of detecting crack of a wafer in a simple method.SOLUTION: A method for detecting crack of a wafer comprises the steps of: preparing wafer holding means with a transparent or translucent holding member which holds the whole surface of a wafer and a luminous body arranged on the side opposite to a holding surface of the holding member; holding the wafer on the holding surface of the wafer holding means; making the luminous body emit light while holding the wafer by the holding means (light emitting step); imaging the wafer by the imaging means arranged facing the wafer held by the wafer holding means when the light emitting step is being performed; and detecting a location from which light from the luminous body leaks in the region in which the wafer is located from the image acquired by the imaging step as the crack of the wafer (crack detecting step).

Description

  The present invention relates to a crack detection method and a crack detection apparatus for detecting a crack in a wafer.

  Semiconductor wafers defined by dividing lines (streets) in which a number of devices such as ICs and LSIs are formed on the surface and each device is formed in a lattice shape are ground to a predetermined thickness by a grinding machine. After being processed, the line to be divided is cut by a dicing apparatus to be divided into individual devices, and the divided devices are widely used in various electric devices such as mobile phones and personal computers.

  A grinding apparatus for grinding a back surface of a wafer includes a chuck table for holding a wafer, and a grinding means on which a grinding wheel having a grinding wheel for grinding the wafer held on the chuck table is rotatably mounted. The wafer can be ground to a desired thickness with high accuracy.

  However, when grinding the wafer, or when polishing the wafer dry or wet, clogging occurs in the grinding wheel and polishing cloth, or a lump containing abrasive grains constituting the grinding wheel is removed from the grinding wheel. Due to falling off or changing the degree of application of grinding water or polishing liquid, unpredictable load is applied to the wafer, and minute cracks that cannot be confirmed with the naked eye occur inside or outside the wafer. There's a problem.

JP 2005-153090 A

  When fine cracks occur in the wafer, when the wafer is attached to the dicing tape and supported by the annular frame, the wafer is completely broken to reduce the work efficiency, or the wafer is supported by the annular frame via the dicing tape. There is a problem that the wafer is cracked when dicing the wafer, and as a result, a line to be divided is displaced and a large number of defective devices are generated.

  The present invention has been made in view of these points, and an object of the present invention is to provide a wafer crack detection method and a crack detection apparatus capable of detecting a wafer crack by a simple method.

  According to the first aspect of the present invention, there is provided a wafer crack detection method for detecting a wafer crack, wherein a transparent or translucent holding member that holds the entire surface of the wafer is disposed on the opposite side of the holding surface of the holding member. A wafer holding means preparing step for preparing a wafer holding means provided with a light emitter, a wafer holding step for holding the wafer on the holding surface of the wafer holding means, and holding the wafer by the holding means. A light emission step for causing the light emitter to emit light, an imaging step for imaging the wafer with an imaging means disposed facing the wafer held by the wafer holding means during the light emission step, and an imaging step A crack detection step for detecting, as a crack in the wafer, a portion where light from the light emitter leaks from the obtained captured image in a region where the wafer is located Cracking method for detecting a wafer, characterized in that it comprises a are provided.

  According to a third aspect of the present invention, there is provided a wafer crack detection device, comprising: a transparent or translucent holding member that holds the entire surface of the wafer; and a light emitter disposed on the opposite side of the holding surface of the holding member; A wafer holding means, an imaging means that faces the holding surface of the wafer holding means and images the wafer held on the holding surface in a state where the light emitter emits light, and an image picked up by the imaging means Image analysis means for analyzing an image, and the image analysis means detects a portion where light from the light emitter leaks as a crack in the wafer in a region where the wafer is located from the captured image. A wafer crack detection device is provided.

  According to the present invention, utilizing the fact that light leaks from the cracks in the wafer, the wafer held by the wafer holding means having the light emitter disposed on the lower side is imaged by the imaging means, and the leaked light in the captured image is detected. As a result, it is possible to easily and automatically detect cracks in the wafer.

  This makes it possible to automatically separate the broken wafers, so that it is not necessary to allocate workers to confirm the cracks after grinding, for example, and the broken wafers are not sent to the next process. Play.

It is a perspective view of the grinding device provided with the crack detection device of the present invention. 1 is a perspective view of a wafer crack detection device according to an embodiment of the present invention. It is a partial cross section side view of a wafer crack detection device. It is a figure which shows an example of a captured image.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, there is shown a perspective view of a grinding apparatus 2 equipped with a wafer crack detection apparatus according to an embodiment of the present invention. Reference numeral 4 denotes a base of the grinding apparatus 2, and a column 6 is erected on the rear side of the base 4. A pair of guide rails (only one is shown) 8 extending in the vertical direction is fixed to the column 6.

  A grinding unit (grinding means) 10 is mounted along the pair of guide rails 8 so as to be movable in the vertical direction. The grinding unit 10 is attached to a moving base 12 whose housing 20 moves in the vertical direction along a pair of guide rails 8.

  The grinding unit 10 includes a housing 20, a spindle (not shown) rotatably accommodated in the housing 20, a servo motor 22 that rotationally drives the spindle, and a plurality of grinding wheels 26 fixed to the tip of the spindle. 24.

  The grinding unit 10 includes a grinding unit feed mechanism 18 including a ball screw 14 and a pulse motor 16 that move the grinding unit 10 up and down along a pair of guide rails 8. When the pulse motor 16 is driven, the ball screw 14 rotates and the moving base 12 is moved in the vertical direction.

  A chuck table mechanism 28 is disposed at an intermediate portion of the base 4, and the chuck table mechanism 28 is moved in the Y-axis direction by a chuck table moving mechanism (not shown). A bellows 32 covers the chuck table mechanism 28.

  The chuck table mechanism 28 includes a chuck table 30 that is rotationally driven. The chuck table 30 includes a frame body 30a, and an upper surface of the frame body 30a and a suction holding portion 30b made of porous ceramics or the like in which the holding surface is formed flush with each other.

  A first thickness measuring device 34 and a second thickness measuring device 36 are disposed adjacent to the chuck table 30. The measuring needle of the first thickness measuring device 34 contacts the upper surface of the frame body 30a of the chuck table 30 to detect the height of the frame body 30a. The measuring needle of the second thickness measuring device 36 contacts the surface of the wafer sucked and held by the chuck table 30 to detect the height of the surface of the wafer.

  By subtracting the height of the chuck table 30 detected by the first thickness measuring device 34 from the height of the surface of the wafer detected by the second thickness measuring device 36, the thickness of the wafer can be calculated.

  A pre-processed wafer storage cassette 38, a processed wafer storage cassette 40, and a broken wafer storage cassette 42 are disposed in the front portion of the base 4. The front portion of the base 4 further includes a wafer transfer robot 44, a positioning mechanism 46 having a plurality of positioning pins 48, a wafer carry-in mechanism (loading arm) 50, a wafer carry-out mechanism (unloading arm) 52, and a spinner cleaning. A unit 54 is provided.

  The spinner cleaning unit 54 also serves as a wafer crack detection device, and has a rotatable holding table 56 that acts as a wafer holding means. Reference numeral 58 denotes an exterior cover of the grinding apparatus 2, and an imaging unit (imaging unit) 60 that captures an image of the wafer held on the holding table 56 is attached to the exterior cover 58.

  Hereinafter, the operation of the grinding apparatus of this embodiment will be described. The unprocessed wafer 11 (see FIG. 3) accommodated in the unprocessed wafer storage cassette 38 is taken out from the cassette 38 by the wafer transfer robot 44 and is centered by the positioning mechanism 46.

  Next, by the turning operation of the wafer carry-in mechanism 50, the wafer 11 is carried into the chuck table 30 positioned at the wafer carry-in / out position, the wafer 11 is sucked and held by the chuck table 30, and the chuck table 30 moves in the Y-axis direction. And positioned in the grinding position.

  While rotating the chuck table 30 positioned at the grinding position at, for example, 300 rpm, the servo motor 22 is driven to rotate the grinding wheel 24 at, for example, 6000 rpm, and the pulse motor 16 of the grinding unit feeding mechanism 18 is driven to drive the grinding unit. 15 is lowered at a predetermined feed rate.

  While detecting the height of the wafer 11 with the second thickness measuring device 36, the grinding wheel 26 of the grinding wheel 24 is pressed against the wafer 11 held on the chuck table 30 with a predetermined load, thereby causing the wafer 11 to have a desired thickness. To grind.

  After grinding, the chuck table 30 is returned to the wafer carry-in / carry-out position, and then the wafer 11 that has been ground by the turning operation of the wafer carry-out mechanism 52 is transferred onto the holding table 56 of the spinner cleaning unit / wafer crack detection device 54. The ground wafer 11 is sucked and held by the holding table 56. The wafer 11 is cleaned by rotating the holding table 56 while supplying the cleaning water, and then the wafer 11 is spin-dried without supplying the cleaning water.

  After the spin drying, the imaging unit 60 images the wafer 11 held on the holding table 56, and the wafer crack detection device 54 described in detail with reference to FIGS. To detect.

  The ground wafer that has been detected as having no cracks is housed in the processed wafer storage cassette 40 by the wafer transport robot 44, and the wafer in which the crack has been detected is stored in the cracked wafer storage cassette 42 by the wafer transport robot 44. Is done.

  Hereinafter, the wafer crack detection device 54 will be described in detail with reference to FIGS. 2 to 4. As best shown in FIG. 3, the holding table 56 of the wafer crack detection device 54 is provided with a plurality of light emitters 64 made of, for example, LEDs or the like in a circular recess 63 formed in the base 62. .

  A holding member 66 made of a transparent material such as quartz is fitted into the fitting portion 65 formed on the circular recess 63. A plurality of through holes 68 are formed in the holding member 66, and these through holes 68 are connected to a suction source (not shown) through a suction path 70.

  The wafer 11 has a protective tape T attached to the surface thereof, and the back surface of the wafer 11 is ground in this state. After the wafer 11 that has been ground is sucked and held via the protective tape T by the holding table 56 of the spinner cleaning unit / wafer crack detection device 54, the wafer 11 is cleaned and spin-dried.

  After the spin drying, the light emitter 64 is turned on and the wafer 11 is imaged by the imaging unit 60. The imaging unit 60 is connected to an image analysis means 72, and the image analysis means 72 is connected to a monitor 74 shown in FIG.

  Since the protective tape T is made of a translucent material, the light from the light emitter 64 passes through the transparent holding member 66 and the protective tape T and enters the wafer 11. Since the wafer 11 is formed of an opaque member such as an optical device wafer having a film formed on the silicon or tape side, the light from the light emitter 64 does not pass through the wafer 11 and the wafer imaged by the imaging unit 60. When the 11 imaged images are analyzed by the image analysis means 72, the entire region where the wafer is located is displayed in black.

  However, if there is a crack 13 in the ground wafer 11, the leakage light 15 is emitted from the crack 13. Therefore, in the captured image displayed on the monitor 74 in FIG. 4, the leakage light 15 corresponding to the crack 13 is displayed in white. Is done. Therefore, by detecting the leakage light 15, it can be detected that there is a crack in the wafer 11 after grinding.

  In the embodiment described above, the example in which the crack detection device of the present invention is arranged in the spinner cleaning unit portion of the grinding device 2 has been described. However, the present invention is not limited to this, and is used as a single crack detection device. can do.

2 Grinding device 10 Grinding unit 11 Wafer 13 Crack 15 Leakage light 24 Grinding wheel 30 Chuck table 38 Wafer housing cassette 40 before processing Wafer housing cassette 42 Wafer housing cassette 54 Cracked wafer housing cassette 54 Cleaning unit / crack detection device 56 Holding table 60 Imaging unit 64 Light emitter 66 Transparent holding member T Protective tape 72 Image analysis means 74 Monitor

Claims (3)

A wafer crack detection method for detecting wafer cracks,
A wafer holding means preparing step for preparing a wafer holding means comprising a transparent or translucent holding member for holding the entire surface of the wafer, and a light emitter disposed on the opposite side of the holding surface of the holding member;
A wafer holding step for holding the wafer on the holding surface of the wafer holding means;
A light emission step of causing the light emitter to emit light while holding the wafer by the holding means;
An imaging step of imaging the wafer with imaging means disposed facing the wafer held by the wafer holding means during the light emission step;
From the captured image obtained in the imaging step, a crack detection step of detecting a location where light from the light emitter leaks in a region where the wafer is located as a crack of the wafer;
A method for detecting cracks in a wafer, comprising:   2. The wafer crack detection method according to claim 1, wherein a protective tape is attached to one side of the wafer. A wafer crack detection device,
A wafer holding means having a transparent or translucent holding member for holding the entire surface of the wafer, and a light emitter disposed on the opposite side of the holding surface of the holding member;
Imaging means for facing the holding surface of the wafer holding means and imaging the wafer held on the holding surface in a state where the light emitter emits light;
Image analysis means for analyzing a captured image captured by the imaging means,
The apparatus for detecting cracks in a wafer, wherein the image analysis means detects, as a crack in the wafer, a portion where light from the light emitter leaks in a region where the wafer is located from the captured image.

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