JP2019145627A - Wafer cutting apparatus and method - Google Patents

Abstract

To provide a wafer cutting apparatus and method for smoothly cutting a wafer.SOLUTION: A grinding apparatus 1 includes: a grindstone 21 that grinds a wafer W having a modified layer RL formed therein; a vibrator 4 that vibrates the grindstone 21; and a slide guide 24 that regulates vibration of the grindstone 21 in the vertical direction V. The grinding apparatus 1 grinds the wafer W while vibrating the grindstone 21, thereby extending a crack c in the wafer W and dividing the wafer.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a wafer cutting apparatus and method for cutting a wafer having a modified layer formed therein.

  Patent Document 1 discloses a cutting apparatus for cutting a semiconductor wafer such as a silicon wafer (hereinafter referred to as “wafer”) into chips. This cutting device is configured to make a main reforming at a position where a laser is incident along the cutting line from the back surface of the wafer and a depth of the pre-reforming region including the micro-holes in the wafer is combined with the pre-reforming region. Form a region. When forming this modified region, microcracks derived from the pre-modified region are extended in the thickness direction of the wafer. Thereafter, the wafer is ground from the back surface to remove the pre-modified region and the main modified region, and the derived micro crack is left, and the micro crack is used as a starting point and is divided into a plurality of chips along the cutting line.

JP 2012-109358 A

  However, in the cutting apparatus as described above, microcracks remaining after grinding and removing the pre-modified region and the main modified region are not continuously formed from the front surface to the back surface of the wafer. When the wafer is divided into chips, it is necessary to divide the wafer into chips starting from microcracks by applying an external force such as by expanding an expanded tape on which the wafer is mounted.

  Thus, a technical problem to be solved in order to smoothly divide the wafer occurs, and the present invention aims to solve this problem.

  In order to achieve the above object, a wafer cutting apparatus according to the present invention cuts the wafer by extending a crack in the wafer by grinding means on the back surface of the wafer on which the modified layer is formed. And a plurality of regulating means for regulating the vibration of the grinding means in the vertical direction.

  According to this configuration, the grinding means grinds the back surface of the wafer while the vibration means vibrates the grinding means, whereby the formation of a crack in the wafer is promoted, and the crack extends from the front surface to the back surface of the wafer. Since it is formed continuously, the wafer can be divided without applying an external force to the wafer.

  In addition, since the plurality of restricting means restrict the direction in which the grinding means vibrates only in the vertical direction, cracks in the wafer are likely to progress vertically, and the cut surface of the divided wafer can be smoothed.

  In order to achieve the above object, the wafer cutting method according to the present invention includes a grinding means for grinding a back surface of a wafer on which a modified layer is formed so as to extend cracks in the wafer. The grinding means performs grinding in a state where the grinding means vibrates in the vertical direction.

  According to this configuration, the grinding means grinds the back surface of the wafer while the vibration means vibrates the grinding means, whereby the formation of a crack in the wafer is promoted, and the crack extends from the front surface to the back surface of the wafer. Since it is formed continuously, the wafer can be divided without applying an external force to the wafer.

  In addition, by grinding the wafer while the grinding means vibrates only in the vertical direction, cracks in the wafer are easily propagated in the vertical direction, and the cut surface of the divided wafer can be made smooth.

  In the present invention, the grinding means grinds the back surface of the wafer while the vibration means vibrates the grinding means, so that the formation of cracks in the wafer is promoted, and the cracks continue from the front surface to the back surface of the wafer. Therefore, the wafer can be divided without applying an external force to the wafer. In addition, by grinding the wafer while the grinding means vibrates only in the vertical direction, cracks in the wafer are easily propagated in the vertical direction, and the cut surface of the divided wafer can be made smooth.

The partial omission perspective view which shows typically the cutting device which concerns on one Embodiment of this invention. The longitudinal cross-sectional view which shows the internal structure of a main unit and a conveyance unit. The top view of a main unit. The schematic diagram which shows a mode that the crack in a wafer progressed. The schematic diagram which shows the cutting device in process.

  Embodiments of the present invention will be described with reference to the drawings. In the following, when referring to the number, numerical value, quantity, range, etc. of the constituent elements, it is limited to the specific number unless otherwise specified and clearly limited to the specific number in principle. It may be more than a specific number or less.

  In addition, when referring to the shapes and positional relationships of components, etc., those that are substantially similar to or similar to the shapes, etc., unless otherwise specified or otherwise considered in principle to be apparent. Including.

  In addition, the drawings may be exaggerated by enlarging characteristic portions in order to make the features easy to understand, and the dimensional ratios and the like of the constituent elements are not always the same. In the cross-sectional view, hatching of some components may be omitted in order to facilitate understanding of the cross-sectional structure of the components.

  FIG. 1 is a perspective view showing a basic configuration of a grinding apparatus 1 in which the spindle feed mechanism 25 and the transport unit 3 are omitted. FIG. 2 is a longitudinal sectional view showing the internal structure of the main unit 2 and the transport unit 3 shown in FIG. FIG. 3 is a plan view of the main unit 2.

  The grinding device 1 functions as a cutting device for cutting the wafer W by grinding the back surface of the wafer W on which the modified layer is formed. The grinding device 1 includes a main unit 2 including a grindstone 21 and a transport unit 3 disposed below the main unit 2.

  The main unit 2 includes an arched column 22, a spindle 23 to which a grindstone 21 is attached, three linear guides 24 that support the spindle 23 so as to be slidable in the vertical direction V, and the spindle 23 is moved up and down in the vertical direction V. A spindle feed mechanism 25 to be moved.

  The spindle 23 is accommodated in a groove 22 b that is recessed in the vertical direction V on the front surface 22 a of the column 22. The spindle 23 includes a saddle 23a with a grindstone 21 attached to the lower end, and a motor (not shown) that is provided in the saddle 23a and rotates the grindstone 21.

  The linear guide 24 includes two front linear guides 24a disposed in front of the column 22 and one rear linear guide 24b disposed in the groove 22b.

  The front linear guide 24a is disposed at the edge of the groove 22b and is attached to support the front end of the saddle 23a. The rear linear guide 24b is disposed at the bottom of the groove 22b and is attached so as to support the rear center of the saddle 23a.

  The front linear guide 24a and the rear linear guide 24b are provided in parallel to each other along the vertical direction V. Accordingly, the front linear guide 24a and the rear linear guide 24b function as guide rails for the saddle 23a. The number of linear guides 24 that support the spindle 23 is not limited to the above-described three cases, and may be two or four or more.

  The spindle feed mechanism 25 includes a slider 25a coupled to the saddle 23a, a ball screw 25b that moves the slider 25a up and down, and a motor 25c that rotates the ball screw 25b. The motor 25c is driven to rotate the ball screw 25b forward, and the slider 25a is lowered in the feeding direction D2 of the ball screw 25b parallel to the vertical direction V, so that the saddle 23a is lowered.

  The main unit 2 is provided with an in-process gauge (not shown) that measures the thickness of the wafer W. When the thickness of the wafer W measured by the in-process gauge reaches a desired value, the motor 25c is driven to rotate the ball screw 25b in reverse, and the saddle 23a connected to the slider 25a is raised, so that the wafer W and the grindstone 21 are increased. Are separated from each other.

  The main unit 2 is provided with a known in-process gauge (not shown) for measuring the thickness of the wafer W. When the thickness of the wafer W measured by the in-process gauge reaches a desired value, the motor 25c is driven to rotate the ball screw 25b in reverse, and the saddle 23a connected to the slider 25a is raised, so that the wafer W and the grindstone 21 are increased. Are separated from each other.

  The main unit 2 is provided with a vibrator 4 that vibrates the grindstone 21 during processing. Specifically, the vibrator 4 is attached to the spindle 23. The vibration of the vibrator 4 may be in the vertical direction V or the horizontal direction.

  The transfer unit 3 includes a chuck 31 that can hold the wafer W by suction, a slider 32 on which the chuck 31 is placed, and a slider drive mechanism 33 that drives the slider 32.

  The chuck 31 is connected to a vacuum source (not shown) and can vacuum-suck the wafer W onto the chuck 31. Further, the chuck 31 can be rotated around a vertical axis passing through the center of the chuck 31 by a motor 31a.

  The slider 32 can slide on the rail 32a, so that the chuck 31 and the slider 32 slide together.

  The slider drive mechanism 33 slides the slider 32 by a motor 33b via a belt / pulley mechanism 33a. Thus, the wafer W vacuum-sucked on the chuck 31 is carried to the lower part of the grindstone 21 by the slider 32 before the grinding process, and is carried out from the lower part of the grindstone 21 to the rear of the main unit 2 after the grinding process. The

  The operation of the grinding apparatus 1 is controlled by a control unit 5 (not shown). The control unit 5 controls each component constituting the grinding apparatus 1. The control unit 5 is constituted by, for example, a CPU, a memory, and the like. The function of the control unit 5 may be realized by controlling using software, or may be realized by operating using hardware.

  Next, the operation of the grinding apparatus 1 will be described based on the drawings. FIG. 4 is a schematic diagram showing how the crack c in the wafer W progresses. FIG. 5 is a schematic diagram showing a state in which the grinding apparatus 1 is grinding the back surface of the wafer W.

  The grinding apparatus 1 grinds the back surface w2 (surface opposite to the surface w1 on which the device is formed) of a substrate made of difficult-to-cut material such as sapphire or silicon carbide. As shown to Fig.4 (a), the bag grind tape 6 is affixed on the surface w1 in which the wafer W which the grinding apparatus 1 grinds formed the device. A modified layer RL is formed inside the wafer W.

  The modified layer RL is a modified region in which a laser incident from the back surface w2 of the wafer W placed on the table 7 is condensed inside the wafer W, and is a minute hole at the condensing point of the laser. The RR is formed, and the micro crack c is formed vertically from the modified region RR vertically, that is, in the thickness direction of the wafer W. Such laser processing is performed under conditions where BHC (Backside half cut) does not occur in the pattern of the wafer W.

  The modified layer RL can be formed at a desired position by moving the condensing point of the laser, and is formed along a planned dividing line when the wafer W is divided into chips. In the wafer W shown in FIG. 4A, the modified regions RR are formed at predetermined intervals along the radial direction and the thickness direction of the wafer W.

  As shown in FIG. 4B, when the front surface w <b> 1 of the wafer W having the modified layer RL formed therein is sucked and held by the chuck 31 and the back surface of the wafer W is ground by the grindstone 21, Although the crack c progresses vertically, the crack c is not continuously formed from the front surface w1 to the rear surface w2 of the wafer W only by grinding the back surface w2 of the wafer W with the grindstone 21. In some cases, the wafer W has to be cleaved starting from the crack c by applying an external force or the like.

  However, as shown in FIG. 5, when the vibrator 4 vibrates the grindstone 21, the grindstone 21 grinds the back surface w2 of the wafer W, thereby promoting the formation of cracks c in the wafer W, as shown in FIG. ), Since the crack c is continuously formed from the front surface w1 to the rear surface w2 in the wafer W, the wafer W can be divided without applying an external force to the wafer W.

  Further, since the linear guide 24 regulates the direction in which the grindstone 21 vibrates only in the vertical direction V, the crack c in the wafer W is likely to progress vertically up and down, and the cut surface of the divided wafer W is smoothed. can do.

  The present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

DESCRIPTION OF SYMBOLS 1 ... Grinding device 2 ... Main unit 3 ... Conveyance unit 4 ... Vibrator (vibration means)
DESCRIPTION OF SYMBOLS 5 ... Control unit 6 ... Bag grind tape 7 ... Table 21 ... Grinding wheel 22 ... Column 22a ... Front 22b ... Groove 23 ... Spindle 23a ... Saddle 24 ..Linear guide (regulation means)
24a ... front linear guide 24b ... rear linear guide 25 ... spindle feed mechanism 25a ... (spindle feed mechanism) slider 25b ... ball screw 25c ... (spindle feed mechanism) motor 31・ Chuck 31a... (Chuck) motor 32... (Conveyor unit) slider 32a... Rail 33... Slider drive mechanism 33a. ) Motor D2 ... feeding direction RL ... modified layer RR ... modified region V ... vertical direction W ... wafer c ... crack w1 ... front surface w2 ... back surface

Claims (2)

A wafer cutting device for cutting the wafer by grinding a wafer having a modified layer formed therein, extending a crack in the wafer, and cutting the wafer.
Vibration means for vibrating the grinding means;
A plurality of regulating means for regulating the vibration of the grinding means in the vertical direction;
A wafer cutting apparatus comprising: A wafer cutting method in which a grinding means grinds a wafer in which a modified layer is formed and extends a crack in the wafer to divide the wafer.
The wafer cutting method, wherein the grinding means performs grinding in a state where the grinding means vibrates in the vertical direction.