TW201937578A - Method for processing workpiece wherein the grinding water containing grinding debris is prevented from intruding into the gap between adjacent chips - Google Patents

Abstract

[Problem] Even if the workpiece is formed to the finished thickness, the grinding water containing grinding chips will not be allowed to penetrate into the gap between adjacent wafers. [Solution] The method for processing a workpiece includes: a front protection step covering the front surface Wa of the workpiece W with the front protection member 1; a heating step of the protection member to harden and shrink the adhesive material of the front protection member 1; Internally formed a deteriorating layer M: a back grinding step, grinding the back Wa of the workpiece W to form a finished wafer thickness; and a protective member expansion step that divides the workpiece W into individual wafers C and expands the wafer interval 7 because it is composed of In the heating step of the protective member, the adhesive material of the front protective member 1 is hardened and shrunk, thereby forming an undivided area where the wafer is not completely divided in the back grinding step, so that there is no gap between the wafers C during the back grinding, and It is possible to prevent the grinding chips from adhering to the side of the wafer C.

Description

Workpiece processing method

The invention relates to a workpiece processing method.

In the semiconductor device manufacturing process, a plurality of areas are formed on a front surface of a workpiece having a substantially circular plate shape through a grid-like predetermined dividing line called a scribe line, and circuits (functional elements) such as ICs and LSIs are formed in the divided areas. . Then, the workpiece is cut along a predetermined division line, thereby dividing a region where a circuit is formed to manufacture each wafer.

As a method of cutting a workpiece along a predetermined division line, there is a laser processing method in which a condensing point is aligned inside a region to be divided to irradiate a pulsed laser light which is penetrating to the workpiece. In the segmentation method using this laser processing method, the light-condensing point is focused on the inside from one surface side of the workpiece to irradiate pulsed laser light in the infrared light range which penetrates the workpiece, and is divided along the interior of the workpiece. A predetermined line continuously forms a deteriorated layer, and along the divided predetermined line whose strength is reduced by forming the deteriorated layer, and by grinding the back surface of the workpiece, the workpiece can be broken and divided into individual wafers (for example, refer to the following patent) Literature 1).

[Xizhi technical literature]
[Patent Literature]
[Patent Document 1] Japanese Patent No. 4733934

[Problems to be Solved by the Invention]
However, since gaps are generated between the divided wafers, when grinding is performed up to the finished thickness after the wafer is divided, grinding water including grinding chips penetrates into the gaps between the wafers, and grinding chips adhere to the sides of the wafer. Grinding chips adhering to the side of the wafer are extremely difficult to remove even if they are cleaned by the cleaning mechanism of the grinding device.

The present invention has been made in view of the above circumstances, and an object thereof is to prevent the grinding water containing grinding chips from penetrating into the gap between adjacent wafers even if the workpiece is formed to a finished thickness.

[Technical means to solve the problem]
The invention is a workpiece processing method. The workpiece is divided into individual wafers along a predetermined division line. The workpiece is formed with functional elements in an area divided by a predetermined division line forming a grid shape on the front side. The workpiece processing method includes : A front protection step, covering the front surface of the workpiece with the front surface protective member to form the area where the functional element is formed; a protective member heating step, so that the adhesive material of the front protective member hardens and shrinks; a metamorphic layer forming step, starting from the back side of the workpiece The laser beam which penetrates the workpiece is irradiated at a predetermined division line, and a deteriorated layer is formed on the back side at a position corresponding to the finished thickness of the wafer. The back grinding step grinds the back of the workpiece with the deteriorated layer formed, and the wafer is formed to completion. Thickness; and a step of expanding the protective member, dividing the workpiece into individual wafers, and expanding the wafer interval, in the heating step of the protective member, the adhesive material of the front protective member is hardened and shrunk, whereby the wafer is divided in the back grinding step. An incomplete undivided area is formed on the workpiece. The front surface protection member is preferably an adhesive film.

[Inventive effect]
The method for processing a workpiece according to the present invention includes: a front protection step, covering a front surface of the workpiece with a functional element formed on the front surface of the workpiece; a heating step of the protection member to harden and shrink an adhesive material of the front protection member; and a step of forming a metamorphic layer from the workpiece. The rear side of the laser beam is irradiated with laser light penetrating through the workpiece along a predetermined division line, and a deteriorated layer is formed on the rear side at a position corresponding to the finished thickness of the wafer. Forming to the finished thickness; and a step of expanding the protective member, dividing the workpiece into individual wafers and expanding the wafer interval, since the adhesive member of the front protective member is hardened and shrunk during the heating step of the protective member, thereby performing the back grinding step. The undivided region where the middle wafer is not completely divided is formed on the workpiece, so that cracks generated from the metamorphic layer during back grinding are prevented from extending to the front side of the workpiece, so that there is no gap between the wafers. As described above, according to the present invention, it is possible to prevent the worry that the grinding water including the grinding chips penetrates into the side surface of the wafer, and prevent the grinding chips from adhering to the side surface of the wafer. When the front surface protection member is made of an adhesive film, the front surface protection step can be easily performed.

The workpiece W shown in FIG. 1 has a circular plate-like substrate, and functional elements (elements in the example shown in the figure) are formed in each region divided by a plurality of predetermined division lines S forming a grid shape on the front surface Wa of the substrate. D). The back surface Wb, which is opposite to the front surface Wa of the workpiece W, is a surface to be processed to which a predetermined process is to be performed. The material, thickness, and size of the work W are not particularly limited. Hereinafter, a workpiece processing method of dividing the workpiece W into individual wafers along the planned division line S will be described.

(1) Front protection step As shown in FIG. 1, the area where the element D is formed on the front surface Wa of the workpiece W is covered with the front protection member 1. The front protective member 1 shown in this embodiment has adhesiveness and has a size approximately the same as the diameter of the workpiece W. The front protective member 1 is preferably an adhesive film in which an adhesive material is laminated on a base material composed of, for example, polyolefin, polyvinyl chloride, or the like. The front surface protection member 1 is adhered to the front surface Wa of the work W, and covers the entire surface of the surface Wa, thereby protecting each element D. Since the front protection member 1 is composed of an adhesive film, the front protection step can be easily performed. Although not shown in the drawings, the front surface protection step may be performed by, for example, applying an adhesive film to a film bonding machine for the front surface Wa of the workpiece W.

(2) Protective member heating step As shown in FIG. 2, the side of the front protective member 1 to which the workpiece W is self-adhesive is placed on the heating member 2 to heat the front protective member 1. The heating member 2 is composed of, for example, an infrared heater. In the heating member 2, the front surface protection member 1 is heated at 80 ° C. for about 1 minute, thereby hardening and shrinking the adhesive material of the front surface protection member 1. Thereby, since the adhesive material of the front surface protection member 1 becomes hard, when the back surface grinding process mentioned later is performed, the influence of the stress at the time of grinding can be reduced and the movement of an adjacent wafer can be suppressed. The heating member 2 may be constituted by a heater that sprays hot air on the front protective member 1 to warm the adhesive. The protective member heating step may be performed in the above-mentioned adhesive film laminating machine, or may be performed in a laser processing apparatus 3 described later.

(3) Step of Forming Modified Layer Next, the workpiece W is transferred to the laser processing apparatus 3 shown in FIG. 3 (a), and a modified layer M is formed inside the workpiece W by laser processing. The laser processing apparatus 3 includes at least a holding table 30 holding a workpiece W, and a laser processing means 31 disposed on the upper side of the holding table 30. The upper surface of the holding table 30 receives a suction action from a suction source (not shown), and becomes a holding surface 30a for holding and holding the workpiece W. A moving means is connected below the holding table 30 to relatively move the holding platform 30 and the laser processing means 31 in a horizontal direction (X-axis direction and Y-axis direction) orthogonal to the vertical direction.

The laser processing means 31 includes a laser head 32 for radiating laser light LB having a penetrating wavelength to the workpiece W held on the holding table 30, and a housing 33 to which the laser head 32 is attached at the front end. An oscillator that oscillates the laser light LB and an output adjuster that adjusts the output of the laser light LB are housed in the housing 33. The laser head 32 contains an internal laser for focusing the laser light LB oscillated by the oscillator. Condensing lens for light. In addition, the laser processing means 31 includes a position adjustment unit (not shown) for adjusting the position of the light-condensing point of the laser light LB collected by the condenser lens. An imaging device 34 is arranged on the side of the casing 33. The imaging means 34 is, for example, an infrared camera including a CCD image sensor.

When the step of forming a deteriorated layer is performed, the workpiece W is held on the holding surface 30 a of the holding table 30 through the front protective member 1 with the front side Wa facing downward. The holding table 30 is positioned directly below the imaging means 34, and the workpiece W is photographed from above through the imaging means 34, and image processing such as pattern matching is performed, thereby detecting the region (the division line S) where the laser light LB should be irradiated.

Next, the laser head 32 is lowered in a direction approaching the workpiece W, and as shown in FIG. 3 (b), the laser beam LB having a wavelength penetrating to the workpiece W is positioned at a predetermined spot inside the workpiece W. Position, in this state, while processing the feed holding table 30 in the X-axis direction at a predetermined processing feed rate, the laser head 32 is irradiated from the back surface Wb side of the workpiece W along the planned division line S shown in FIG. 1 through the laser head 32 A modified layer M is formed on the back surface Wb side at a position corresponding to the finished thickness of the wafer. The metamorphic layer M is a region where the strength or physical characteristics of the workpiece W change, and serves as a starting point for division when the workpiece W is divided into individual wafers.

Whenever the laser light LB is irradiated along one predetermined division line S to form the deteriorated layer M, the holding table 30 is indexed in the Y-axis direction to irradiate the laser ray LB along the next predetermined division line S. After the laser beam LB is irradiated to all the planned division lines S in the X-axis direction, the holding table 30 shown in FIG. 3 (a) is rotated 90 ° so that the planned division lines S in the Y-axis direction are toward X Axis direction. Then, the same laser processing as described above is repeatedly performed along all the planned division lines S to form a modified layer M along the planned division lines S.

(4) Back Surface Grinding Step Next, using the grinding device 4 shown in FIG. 4 (a), the back surface Wb of the workpiece W is ground to form a wafer with a completed thickness. The grinding apparatus 4 includes a holding table 40 that holds the workpiece W, a rotation means 41 that rotates the holding table 40, and a grinding means 42 that grinds the workpiece W held on the holding table 40. The upper surface of the holding table 40 receives a suction action from a suction source (not shown), and becomes a holding surface 40a for holding and holding the workpiece W.

The grinding means 42 includes a main shaft 43 having a vertical axis center orthogonal to the holding surface 40a, a grinding wheel 45 mounted on a lower end of the main shaft 43 through a mount 44, and a grinding stone fixed to the lower portion of the grinding wheel 45 in a ring shape. 46. A lifting means (not shown) is connected to the grinding means 42, and the grinding means 42 can be raised and lowered while the grinding wheel 45 is rotated by the lifting means.

In the case of grinding the workpiece W, as shown in FIG. 4 (b), the holding surface 40 a of the holding table 40 is kept adhered to the front protective member 1 side of the front surface Wa of the workpiece W, and the back surface Wb of the workpiece W is exposed upward to make the holding table 40 rotates in the direction of arrow A, for example. Next, the grinding means 42 rotates the grinding wheel 45 at, for example, the arrow direction A at a predetermined grinding feed rate, and grinds the back surface Wb of the workpiece W to the finished thickness of the wafer while pressing the rotating grinding stone 46. During the grinding of the workpiece W, although not shown, grinding water is supplied to the contact surface between the rotating grinding stone 46 and the workpiece W.

In the back grinding step, since the adhesive material of the front protection member 1 is hardened and contracted in the above-mentioned heating step of the protection member, the grinding process is performed to form the workpiece W to a finished thickness, even if the stress during grinding acts on the front protection member 1, Since the front protective member 1 does not flex, movement of the wafer is suppressed, and an undivided area where the wafer is not completely divided is formed on the workpiece W. In this undivided area, no gap is formed between adjacent wafers, and there is no doubt that grinding water mixed with grinding chips will penetrate into the gap. When the workpiece W reaches the finished thickness, a region of the wafer W is also locally generated on the workpiece W and is divided into wafers with the metamorphic layer M as the starting point. Since it becomes hard, the workpiece W can be formed to a finished thickness while maintaining the circular plate-like shape with the workpiece W as a whole.

(5) The expansion step of the protective member is shown in FIG. 5 (a). For example, using the expansion device 5, the workpiece W is divided into individual wafers C, and the wafer interval 7 is expanded. The expansion device 5 includes a support table 50 that supports the workpiece W from below, a frame mounting table 51 on which a frame F that is disposed on the outer peripheral side of the support table 50 and has an opening at the center, and a frame mounting table 51 The clamp portion 52 of the frame F and the lifting means 53 connected to the lower portion of the frame mounting table 51 and lifting the frame mounting table 51 in the vertical direction. The lifting mechanism 53 is composed of a pressure cylinder 53a and a piston 53b driven by the pressure cylinder 53a to move up and down, and the frame mounting table 51 can be moved up and down by moving the piston 53b up and down.

When transporting the workpiece W to the expansion device 5, the front and back surfaces of the workpiece W are reversed, and the back surface Wb of the workpiece W is adhered to the adhesive film T exposed from the opening attached to the frame F, and peeled from the front surface Wa of the workpiece W. FIG. 4 Shown the front protective member 1. In this way, the frame F and the work W are integrated in advance through the adhesive film T. Although the workpiece W after the back grinding step is not completely divided, a crack 6 is generated between the adjacent wafers C from the deteriorated layer M shown in FIG. 4 (a) in the workpiece thickness direction. This crack 6 does not extend to the front side Wa of the workpiece W.

The work W penetrates the adhesive film T, the back surface Wb side of the work W is placed on the support table 50, and the frame F is placed on the frame mounting table 51. It fixes so that the upper surface of the frame F may be pressed by the clamp part 52, without moving. As shown in FIG. 5 (b), the piston 53 b moves downward and lowers the frame mounting table 51, and lowers the frame mounting table 51 relative to the support table 50. Accordingly, when the adhesive film T is radially expanded, an external force in the radial direction is applied to the workpiece W, and the workpiece W is divided into individual wafers C along the crack 6. Since cracks 6 occur between adjacent wafers C, the wafer C of the workpiece W can be easily divided completely by expanding the adhesive film T. The wafer interval 7 between adjacent wafers C is expanded by a predetermined expansion amount of the expansion film T. Then, after forming a wafer interval 7 between all adjacent wafers C, the protective member expansion step is completed. The divided wafer C is picked up by a carry-out means (not shown) and transferred to the next process.

As described above, the method for processing a workpiece according to the present invention includes a front protection step, which covers the area where the element D is formed on the front surface Wa of the workpiece W with the front protection member 1, and a step of heating the protection member to harden and shrink the adhesive material of the front protection member 1. Step of forming a deteriorated layer, irradiate a laser beam LB penetrating to the workpiece W along the predetermined division line S from the back surface Wb side of the workpiece W, and form a deteriorated layer M on the back surface Wb side at a position corresponding to the finished thickness of the wafer The back grinding step is to grind the back Wa of the workpiece W with the modified layer M formed to the wafer finished thickness; and the protective member expansion step is to divide the workpiece W into individual wafers C and expand the wafer interval 7 because it is constituted as In the heating step of the protective member, the adhesive material of the front protective member 1 is hardened and shrunk, thereby forming an undivided area in which the wafer is not completely divided in the back grinding step, thereby preventing cracks 6 generated from the metamorphic layer M during the back grinding. Extending to the front side Wa of the workpiece W, no gap is generated between the wafers C. Therefore, it is possible to prevent the possibility that the grinding water including the grinding chips penetrates the side surface of the wafer C, and prevent the grinding chips from adhering to the side surface of the wafer C.

1‧‧‧ Front protection member

2‧‧‧Heating components

3‧‧‧laser processing device

30‧‧‧holding table

31‧‧‧laser processing methods

32‧‧‧laser head

33‧‧‧shell

34‧‧‧ camera means

4‧‧‧ Grinding methods

40‧‧‧holding table

41‧‧‧ Rotation means

42‧‧‧ Grinding methods

43‧‧‧ Spindle

44‧‧‧Mounting parts

45‧‧‧grinding wheel

46‧‧‧ Grinding Grinding Stone

5‧‧‧Expansion device

50‧‧‧ support

51‧‧‧Frame mounting table

52‧‧‧Jig Department

53‧‧‧ Lifting means

53a‧‧‧Press Cylinder

53b‧‧‧Piston

6‧‧‧ Crack

7‧‧‧ Wafer interval

FIG. 1 is a perspective view showing a front protection step.

Fig. 2 is a sectional view showing a heating step of the protective member.

Fig. 3 is a perspective view and a cross-sectional view showing a step of forming a deteriorated layer.

FIG. 4 is a perspective view and a cross-sectional view showing a back grinding process.

Fig. 5 is a cross-sectional view showing a step of expanding the protective member.

Claims (2)

A workpiece processing method divides a workpiece into individual wafers along a predetermined division line, and the workpiece is formed with functional elements in an area divided by a predetermined division line forming a grid shape on the front side, wherein the workpiece processing method includes: A front protection step, covering the area where the functional element is formed on the front side of the workpiece with a front side protection member; The heating step of the protective member, so that the adhesive material of the front protective member hardens and shrinks; A step of forming a deteriorated layer, irradiating laser light having a penetrability to the workpiece along a predetermined division line from the back side of the workpiece, and forming the deteriorated layer on the back side at a position corresponding to the finished thickness of the wafer; A back grinding step, grinding the back of the workpiece with the modified layer formed, and forming the wafer to a finished thickness; and The protective member expansion step divides the workpiece into individual wafers and expands the wafer interval. In the heating step of the protective member, the adhesive material of the front protective member is hardened and shrunk, whereby an undivided area where the wafer is not completely divided in the back grinding step is formed on the workpiece. The workpiece processing method described in item 1 of the scope of patent application, wherein: The aforementioned front protective member is an adhesive film.