JP7271086B2 - Wafer cutting device and method - Google Patents

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 device for cutting a semiconductor wafer such as a silicon wafer (hereinafter referred to as "wafer") into chips. This cutting apparatus irradiates a laser beam from the rear surface of the wafer along the cutting line, and the pre-modification region containing microvoids inside the wafer and the pre-modification region at a depth where the pre-modification region joins the pre-modification region. form a region. When forming the main modified region, microcracks derived from the preliminary modified region are extended in the thickness direction of the wafer. After that, the wafer is ground from the back surface to remove the pre-modified region and the main modified region while leaving derived microcracks, and the wafer is divided into a plurality of chips along cutting lines starting from the microcracks.

JP 2012-109358 A

However, in the cutting apparatus as described above, the microcracks remaining after grinding and removing the preliminary modified region and the main modified region are not continuously formed from the front surface to the back surface of the wafer. When cutting a wafer into chips, it is necessary to apply external force such as by expanding an expandable tape on which the wafer is mounted so that the wafer is cut into chips starting from microcracks.

Therefore, there arises a technical problem to be solved in order to smoothly divide the wafer, and an object of the present invention is to solve this problem.

In order to achieve the above object, the wafer cutting apparatus according to the present invention cuts the wafer by grinding the back surface of the wafer having a modified layer formed therein with a grindstone to extend cracks in the wafer. A wafer cutting device, wherein the grindstone is mounted on the lower end of the saddle and provided above the saddle so as to be non-rotatable, vibrating means for independently vibrating the grindstone, and regulating the vibration of the grindstone in the vertical direction. a plurality of regulatory means;

According to this configuration, the whetstone grinds the back surface of the wafer while the whetstone is vibrated by the vibrating means, thereby promoting the formation of cracks in the wafer so that the cracks are continuous from the front surface to the back surface of the wafer. Therefore, the wafer can be cut without applying an external force to the wafer.

In addition, since a plurality of restricting means restricts the direction in which the grindstone vibrates only in the vertical direction, cracks in the wafer tend to propagate vertically, and the cut surface of the wafer after dicing can be made smooth.

Further, in order to achieve the above object, the wafer cutting method according to the present invention grinds the back surface of a wafer having a modified layer formed therein with a whetstone to extend cracks in the wafer and divide the wafer. In this wafer dividing method, grinding is performed in a state in which the grindstone is vertically vibrated solely by a vibrating means provided above a non-rotatable saddle with the grindstone attached to the lower end thereof.

According to this configuration, the whetstone grinds the back surface of the wafer while the whetstone is vibrated by the vibrating means, thereby promoting the formation of cracks in the wafer so that the cracks are continuous from the front surface to the back surface of the wafer. Therefore, the wafer can be cut without applying an external force to the wafer.

Further, by grinding the wafer while the whetstone vibrates only in the vertical direction, cracks in the wafer tend to grow vertically, and the cut surface of the wafer after dicing can be made smooth.

According to the present invention, the whetstone grinds the back surface of the wafer while the whetstone is vibrated by the vibrating means, thereby promoting the formation of cracks in the wafer, and continuously forming the cracks from the front surface to the back surface of the wafer. Therefore, the wafer can be cut without applying an external force to the wafer. Further, by grinding the wafer while the whetstone vibrates only in the vertical direction, cracks in the wafer tend to grow vertically, and the cut surface of the wafer after dicing can be made smooth.

1 is a partially omitted perspective view schematically showing a cutting device according to an embodiment of the present invention; FIG. FIG. 4 is a vertical cross-sectional view showing the internal structure of the main unit and the transport 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 parting apparatus in process.

An embodiment of the present invention will be described based on the drawings. In addition, hereinafter, when referring to the number, numerical value, amount, range, etc. of the constituent elements, unless otherwise specified or clearly limited to a specific number in principle, it is limited to the specific number It does not matter if the number is greater than or less than a certain number.

In addition, when referring to the shape or positional relationship of components, etc., unless otherwise specified or in principle clearly considered otherwise, etc. include.

In addition, the drawings may exaggerate characteristic parts by enlarging them in order to make the characteristics easier to understand. In addition, in cross-sectional views, 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 the basic configuration of the grinding apparatus 1 with the spindle feed mechanism 25 and the transfer unit 3 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. FIG.

The grinding device 1 functions as a cutting device that cuts the wafer W by grinding the back surface of the wafer W having a modified layer formed therein. The grinding device 1 includes a main unit 2 having a whetstone 21 and a transport unit 3 arranged below the main unit 2 .

The main unit 2 includes an arch-shaped column 22, a spindle 23 to which a grindstone 21 is attached, three linear guides 24 that slidably support the spindle 23 in the vertical direction V, and the spindle 23 that moves up and down in the vertical direction V. and a spindle feed mechanism 25 that allows

The spindle 23 is housed in a groove 22b recessed in the vertical direction V in the front surface 22a of the column 22. As shown in FIG. The spindle 23 includes a saddle 23a having a grindstone 21 attached to its lower end, and a motor (not shown) provided in the saddle 23a for rotating the grindstone 21. As shown in FIG.

The linear guides 24 are composed of two front linear guides 24a arranged in front of the column 22 and one rear linear guide 24b arranged in the groove 22b.

A front linear guide 24a is located at the edge of groove 22b and is mounted to support the front end of saddle 23a. A rear linear guide 24b is located at the bottom of the groove 22b and is mounted to support the rear center of the saddle 23a.

The front linear guide 24a and the rear linear guide 24b are provided parallel to each other along the vertical direction V. As shown in FIG. Thus, 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 three, and may be two or four or more.

The spindle feed mechanism 25 includes a slider 25a connected to the saddle 23a, a ball screw 25b that raises and lowers the slider 25a, 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 descends in the feed direction D2 of the ball screw 25b parallel to the vertical direction V, thereby descending the saddle 23a.

The main unit 2 is provided with an in-process gauge (not shown) for measuring the thickness of the wafer W. As shown in FIG. 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 the reverse direction, and the saddle 23a connected to the slider 25a is lifted. 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. As shown in FIG. 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 the reverse direction, and the saddle 23a connected to the slider 25a is lifted. are separated from each other.

The main unit 2 is provided with a vibrator 4 for vibrating 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 in the horizontal direction.

The transfer unit 3 includes a chuck 31 capable of holding 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) so that the wafer W can be vacuum-sucked onto the chuck 31 . Further, the chuck 31 is rotatable about a vertical axis passing through the center of the chuck 31 by a motor 31a.

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

The slider driving mechanism 33 slides the slider 32 by a motor 33b via a belt/pulley mechanism 33a. In this way, the wafer W vacuum-sucked onto the chuck 31 is carried in below the grindstone 21 by the slider 32 before grinding, and carried out from below the grindstone 21 to the rear of the main unit 2 after grinding. be.

The operation of the grinding device 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 composed of, for example, a CPU, a memory, and the like. The functions of the control unit 5 may be realized by controlling using software, or may be realized by operating using hardware.

Next, the action of the grinding device 1 will be described with reference to the drawings. FIG. 4 is a schematic diagram showing how the crack c in the wafer W develops. FIG. 5 is a schematic diagram showing how the grinding apparatus 1 grinds the back surface of the wafer W. As shown in FIG.

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

The modified layer RL is a modified region that is a minute hole at the focal point of the laser when the laser incident from the rear surface w2 of the wafer W placed on the table 7 is focused inside the wafer W. RR is formed, and a minute crack c is generated vertically from this modified region RR, that is, in the thickness direction of the wafer W. As shown in FIG. Such laser processing is performed under conditions in which the pattern of the wafer W is not BHC (backside half cut).

The modified layer RL can be formed at a desired position by moving the focal point of the laser, and is formed along the dividing lines along which 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.

As shown in FIG. 4B, when the chuck 31 holds the front surface w1 of the wafer W having the modified layer RL formed therein by suction, and the grindstone 21 grinds the back surface of the wafer W, the inside of the wafer W becomes Although the crack c develops vertically and vertically, the crack c cannot be continuously formed from the front surface w1 to the back 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 must be broken starting from the crack c by applying an external force or the like.

However, as shown in FIG. 5, when the whetstone 21 grinds the back surface w2 of the wafer W while the vibrator 4 vibrates the whetstone 21, the formation of the crack c in the wafer W is accelerated, resulting in FIG. ), the crack c is continuously formed in the wafer W from the front surface w1 to the back surface w2, so that the wafer W can be divided without applying an external force thereto.

In addition, since the linear guide 24 restricts the direction in which the grindstone 21 vibrates only in the vertical direction V, the crack c in the wafer W tends to grow vertically, and the cut surface of the wafer W after dicing is smooth. can do.

It should be noted that the present invention can be modified in various ways without departing from the spirit of the present invention, and it is a matter of course that the present invention extends to the modified ones.

Reference Signs List 1 Grinding device 2 Main unit 3 Transfer unit 4 Vibrator (vibrating means)
5...Control unit 6...Bag grind tape 7...Table 21...Whetstone 22...Column 22a...Front face 22b...Groove 23...Spindle 23a...Saddle 24...・・・Linear guide (control means)
24a Front linear guide 24b Rear linear guide 25 Spindle feed mechanism 25a (Spindle feed mechanism) Slider 25b Ball screw 25c Motor 31 (of spindle feed mechanism) Chuck 31a Motor 32 (for chuck) Slider 32a (for transport unit) Rail 33 Slider drive mechanism 33a Belt/pulley mechanism 33b (Slider drive mechanism) ) 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 that grinds a wafer having a modified layer formed therein with a grindstone to extend a crack in the wafer and divide the wafer,
a vibrating means provided on the upper part of a saddle which is non-rotatably provided with the grindstone attached to the lower end thereof, and vibrates the grindstone independently ;
a plurality of regulating means for regulating the vibration of the grindstone in the vertical direction;
A wafer cutting device comprising: A wafer dividing method in which a wafer having a modified layer formed therein is ground by a grindstone to extend a crack in the wafer to divide the wafer,
A method for cutting a wafer, wherein the grindstone is vibrated in a vertical direction solely by a vibrating means provided on the upper portion of a non-rotatable saddle having the grindstone attached to the lower end thereof.

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