TWI770280B - Wafer manufacturing method - Google Patents

Abstract

Provided is a wafer manufacturing method capable of dividing a plate-shaped workpiece without using an expansion sheet. Create multiple wafers.

Contains: 1st laser processing step for wave penetrating to workpiece The condensing point of the long laser beam is positioned at the first depth position, the laser beam is irradiated only on the wafer area along the line to divide, and the first modified layer is formed along the line to divide the wafer area. The second laser processing step is to irradiate the laser beam along the predetermined dividing line in a manner that the condensing point of the laser beam of the wavelength having penetrability to the workpiece is positioned at the second depth position to form the remaining area of the outer periphery. a second modified layer having overlapping ends; and a dividing step for applying force to the workpiece to divide the workpiece into individual wafers, wherein the dividing step applies force by heating and cooling to divide the workpiece into individual wafers.

Description

Wafer manufacturing method

The present invention relates to a wafer manufacturing method for producing a plurality of wafers by dividing a plate-shaped workpiece.

There is a known method, in order to divide a plate-shaped workpiece (object to be processed) represented by a wafer into a plurality of wafers, and condense a penetrating laser beam inside the workpiece to form a laser beam through multiphoton absorption. A modified modified layer (modified region) (for example, refer to Patent Document 1). Since the modified layer is weaker than other regions, the workpiece can be divided into a plurality of wafers by applying a force to the workpiece after forming the modified layer along the planned dividing line (dicing line).

When applying force to the workpiece on which the modified layer is formed, for example, a method of expanding by sticking a stretchable expansion sheet (expanding tape) to the workpiece is employed (for example, refer to Patent Document 2). In this method, generally, before forming a modified layer on the workpiece by irradiating a laser beam, an expansion sheet is attached to the workpiece, and after the modification layer is formed, the expansion sheet is expanded to divide the workpiece into a plurality of wafers.

[Previously known technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2002-192370

[Patent Document 2] Japanese Patent Laid-Open No. 2010-206136

However, in the method of expanding the expansion sheet as described above, since the used expansion sheet cannot be reused, the cost required for wafer manufacturing is also likely to increase. In particular, since the high-performance expansion sheet in which the adhesive material is difficult to remain on the wafer is also expensive, when such an expansion sheet is used, the cost required for wafer manufacturing also increases.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a wafer manufacturing method capable of dividing a plate-shaped workpiece to manufacture a plurality of wafers without using an expansion sheet.

According to an aspect of the present invention, there is provided a wafer manufacturing method for manufacturing a plurality of wafers from a workpiece having a wafer area and a peripheral remaining area surrounding the wafer area, the wafer area being divided by a plurality of intersecting predetermined dividing lines a plurality of regions of the wafer, and the method includes: a holding step of directly holding the workpiece with a holding table; and a first laser processing step of applying a laser beam of a wavelength having penetrability to the workpiece after the holding step is performed The converging point of the workpiece is positioned at the first depth position inside the workpiece held on the holding table, and the laser beam is irradiated only on the wafer region of the workpiece along the planned dividing line, and further along the wafer region of the wafer region. At the same time as the first modified layer is formed by dividing the planned line, the remaining outer peripheral area is used as a reinforcing part where the first modified layer is not formed; in the second laser processing step, after the holding step is carried out, the workpiece has a penetrating effect on the workpiece. The light-converging point of the laser beam of the transparent wavelength is positioned at a second depth position different from the first depth inside the workpiece held on the holding table, and the laser beam is irradiated along the predetermined dividing line , and further form a second modified layer which is longer than the first modified layer and overlapped at the end of the remaining peripheral region along the planned dividing line; in the carrying out step, the first laser processing step and the second After the laser processing step, the workpiece is carried out from the holding table; and a dividing step, after the carrying out step is performed, a force is applied to the workpiece to separate the workpiece into the respective wafers, wherein in the dividing step, heating and cooling are performed. The force is applied to divide the workpiece into the individual wafers.

In one aspect of the present invention, after the first laser processing step and the second laser processing step are performed and before the dividing step is performed, a reinforcement portion removing step may be further provided for removing the reinforcement portion. Furthermore, in one aspect of the present invention, the upper surface of the holding table is made of a soft material, and in the holding step, the front side of the workpiece can be held by the soft material.

In the wafer manufacturing method according to one aspect of the present invention, the laser beam is irradiated only on the wafer region of the workpiece, and further along the The first modified layer is formed along the planned dividing line of the wafer region, and the laser beam is irradiated so that the condensing point is positioned at the second depth position, and further, the first modified layer is formed along the planned dividing line and longer than the first modified layer. Since the workpiece is divided into a plurality of wafers by applying force by heating and cooling after the second modified layer overlapped at the ends of the remaining outer peripheral region, there is no need to apply force to the workpiece to divide the wafers into individual wafers. expansion sheet used. In this way, according to the wafer manufacturing method of one aspect of the present invention, it is possible to divide a plate-shaped workpiece and manufacture a plurality of wafers without using an expansion sheet.

In addition, in the wafer manufacturing method according to one aspect of the present invention, only the wafer region of the workpiece is irradiated with a laser beam to form the first modified layer along the line to be divided, and the remaining peripheral region is regarded as not having the first modified layer formed thereon. The reinforcing part of the modified layer, so the wafer area is reinforced through this reinforcing part. Therefore, there is no problem that the workpiece cannot be properly transported due to the fact that the workpiece is divided into individual wafers due to force applied during transportation or the like.

11: Workpiece (worked object)

11a: Front

11b: Back

11c: Wafer area

11d: Peripheral remaining area

13: Divide the predetermined line (cutting road)

15: Area

17: Laser Beam

19: Modified layer

19a: 1st modified layer

19b: Second modified layer

19c: 3rd modified layer

21: Fluid

23: Fissure

25: Wafer

2: Laser processing device

4: Abutment

6: Chuck table (holding table)

6a: Keep Face

6b: Attraction Road

8: Horizontal movement mechanism

10: X-axis guide

12: X-axis moving table

14: X-axis ball screw

16: X-axis pulse motor

18: X-axis ruler

20: Y-axis guide

22: Y-axis moving table

24: Y-axis ball screw

26: Y-axis pulse motor

28: Y-axis ruler

30: Support table

32: Valves

34: Attract Source

36: Support structure

38: Support arm

40: Laser irradiation unit

42: Camera

44: Sheet (porous sheet)

44a: upper surface

52: Dividing device

54: Chuck table (holding table)

54a: Keep Face

54b: Way of Attraction

54c: heater (heating unit)

54d: Road of Attraction

56: Valves

58: Attractive Source

60: Valve parts

62: Cutting unit

64: Spindle

66: Cutting Blade

FIG. 1 is a perspective view schematically showing a configuration example of a workpiece.

FIG. 2 is a perspective view schematically showing a configuration example of a laser processing apparatus.

3(A) is a cross-sectional view for explaining the holding step, and FIG. 3(B) is a cross-sectional view for explaining the first laser processing step and the second laser processing step.

4(A) is a plan view schematically showing the state of the workpiece after the modified layers are formed along all the planned dividing lines, and FIG. 4(B) is a schematic plan view showing the state of the modified layers formed along each planned dividing line sectional view.

5(A) and 5(B) of FIG. 5 are cross-sectional views for explaining the step of removing the reinforcement portion.

FIG. 6 is a cross-sectional view for explaining the dividing step.

7 is a cross-sectional view for explaining a holding step according to a modification.

FIG. 8(A) is a cross-sectional view for explaining the division step according to the modification, and FIG. 8(B) is a plan view schematically showing the state of the workpiece after the division step according to the modification.

Embodiments relating to an aspect of the invention are described with reference to the accompanying drawings. The wafer manufacturing method according to the present embodiment includes a holding step (refer to FIG. 3(A)), a first laser processing step (refer to FIGS. 3(B), 4(A), and 4(B)), a second laser 3(B), 4(A) and 4(B)), carrying out step, reinforcement removing step (refer to FIGS. 5(A) and 5(B)), and dividing step ( Refer to Figure 6).

In the holding step, a workpiece (object to be processed) having a wafer region and a peripheral remaining region surrounding the wafer region is directly held by a chuck table (holding table), and the wafer region is divided through The predetermined line divides a plurality of regions. In the first laser processing step, a laser beam having a wavelength having penetrability to the workpiece is irradiated to form the first modified layer along the line to divide the wafer region, and the remaining peripheral region is regarded as not having the first modified layer formed thereon. Reinforcing part of the modified layer.

In the second laser processing step, a laser beam having penetrability to the workpiece is irradiated to form a second modified layer that is longer than the first modified layer and overlapped at the end of the remaining peripheral region along the line to divide. . In the unloading step, the workpiece is unloaded from the chuck table. In the reinforcement removal step, the reinforcement is removed from the workpiece. In the dividing step, the workpiece is divided into a plurality of wafers by applying force by heating and cooling. Hereinafter, the wafer manufacturing method according to this embodiment will be described in detail.

FIG. 1 is a perspective view schematically showing a configuration example of a workpiece (object to be processed) 11 used in the present embodiment. As shown in FIG. 1 , the workpiece 11 is, for example, a semiconductor made of silicon (Si), gallium arsenide (GaAs), indium phosphide (InP), gallium nitride (GaN), silicon carbide (SiC), etc., sapphire (Al ₂ Dielectrics (insulators) such as O ₃ ), soda glass, borosilicate glass, quartz glass, etc., or ferroelectrics (ferroelectrics such as tantalum lithium acid (LiTaO ₃ ), niobate lithium acid (LiNbO ₃ ), etc. crystal) composed of disc-shaped wafers (substrates).

On the front surface 11 a side of the workpiece 11 , a plurality of regions 15 to be wafers are demarcated by a plurality of intersecting planned dividing lines (dicing lanes) 13 . In addition, below, the substantially circular area|region containing the some area|region 15 which becomes a wafer is called the wafer area|region 11c, and the ring-shaped area|region surrounding the wafer area|region 11c is called the outer periphery remaining area|region 11d.

In each region 15 in the wafer region 11c, as necessary, IC (Integrated Circuit), MEMS (Micro Electro Mechanical Systems), LED (Light Emitting Diode, light emitting diode), and LD are formed as necessary. (Laser Diode, laser diode), photodiode (Photodiode), SAW (Surface Acoustic Wave, surface acoustic wave) filter, BAW (Bulk Acoustic Wave, bulk acoustic wave) filter and other components.

The workpiece 11 is divided along the planned dividing line 13, whereby a plurality of wafers are obtained. Specifically, in the case where the workpiece 11 is a silicon wafer, for example, a wafer that functions as a memory or a sensor can be obtained. When the workpiece 11 is a gallium arsenide substrate, an indium phosphide substrate, or a gallium nitride substrate, for example, a wafer that functions as a light-emitting element, a light-receiving element, or the like can be obtained.

When the workpiece 11 is a silicon carbide substrate, for example, a wafer functioning as a power element or the like can be obtained. When the workpiece 11 is a sapphire substrate, for example, a wafer that functions as a light-emitting element or the like can be obtained. When the workpiece 11 is a glass substrate composed of soda glass, borosilicate glass, quartz glass, or the like, for example, a wafer that functions as an optical part or a cover member (cover glass) can be obtained.

When the workpiece 11 is a ferroelectric substrate (ferroelectric crystal substrate) composed of a ferroelectric such as tantalum lithium acid or niobate lithium acid, for example, a filter, an actuator, or the like can be obtained. the role of the wafer. Furthermore, the material, shape, structure, size, thickness, etc. of the workpiece 11 are not limited. Likewise, the type, number, shape, structure, size, arrangement, etc. of the elements formed in the region 15 to be the wafer are not limited. In the region 15 to be the wafer, no element may be formed.

In the wafer manufacturing method according to the present embodiment, a plurality of wafers are manufactured using a disk-shaped silicon wafer as the workpiece 11 . Specifically, a holding step is performed first, and the workpiece 11 is directly held by the chuck table. FIG. 2 is a perspective view schematically showing a configuration example of the laser processing apparatus used in the present embodiment.

As shown in FIG. 2 , the laser processing apparatus 2 includes a base 4 on which various components are mounted. A horizontal movement mechanism 8 is provided on the upper surface of the base 4, and a chuck table (holding table) 6 for sucking and holding the workpiece 11 moves in the X-axis direction (processing feed direction) and the Y-axis direction (indexing feed direction) )move. The horizontal movement mechanism 8 includes a pair of X-axis guide rails 10 and is fixed to the upper surface of the base 4 so as to be substantially parallel to the X-axis direction.

The X-axis moving stage 12 is slidably mounted on the X-axis guide rail 10 . A nut portion (not shown) is provided on the back side (lower surface side) of the X-axis moving table 12 , and the nut portion is screwed with the X-axis ball screw 14 substantially parallel to the X-axis guide 10 .

One end of the X-axis ball screw 14 is connected to the X-axis pulse motor 16 . By rotating the X-axis ball screw 14 by the X-axis pulse motor 16 , the X-axis moving stage 12 moves in the X-axis direction along the X-axis guide rail 10 . An X-axis scale 18 is provided at a position adjacent to the X-axis guide rail 10 for detecting the position of the X-axis moving stage 12 in the X-axis direction.

A pair of Y-axis guide rails 20 that are substantially parallel to the Y-axis direction are fixed to the front surface (upper surface) of the X-axis moving table 12 . The Y-axis moving stage 22 is slidably mounted on the Y-axis guide 20 . A nut portion (not shown) is provided on the rear side (lower surface side) of the Y-axis moving table 22 , and the nut portion is screwed with a Y-axis ball screw 24 that is substantially parallel to the Y-axis guide 20 .

One end of the Y-axis ball screw 24 is connected to the Y-axis pulse motor 26 . By rotating the Y-axis ball screw 24 by the Y-axis pulse motor 26 , the Y-axis moving stage 22 moves in the Y-axis direction along the Y-axis guide rail 20 . A Y-axis scale 28 is provided at a position adjacent to the Y-axis guide 20 for detecting the position of the Y-axis moving stage 22 in the Y-axis direction.

A support table 30 is provided on the front side (upper surface side) of the Y-axis moving table 22 , and the chuck table 6 is arranged above the support table 30 . The front surface (upper surface) of the chuck table 6 serves as the suction and holding The holding surface 6a of the back surface 11b side (or the front surface 11a side) of the member 11 is provided. The holding surface 6a is made of, for example, a porous material having high hardness such as alumina. However, the holding surface 6a may be formed of a soft material typified by resin such as polyethylene or epoxy resin.

The holding surface 6a is connected to a suction source 34 (see FIG. 3(A) and the like) through a suction path 6b (see FIG. 3(A), etc.) formed inside the chuck table 6, a valve member 32 (see FIG. 3(A), etc.), etc. )Wait). A rotation drive source (not shown) is provided below the chuck table 6, and the chuck table 6 rotates around a rotation axis substantially parallel to the Z-axis direction through the rotation drive source.

A columnar support structure 36 is provided behind the horizontal movement mechanism 8 . A support arm 38 extending in the Y-axis direction is fixed to the upper part of the support structure 36 , and a laser irradiation unit 40 is provided at the front end of the support arm 38 , and the pulse oscillation has wavelengths that are penetrating to the workpiece 11 (hard to absorb wavelengths). The laser beam 17 (refer to FIG. 3(B) ) having a wavelength) is irradiated on the workpiece 11 on the chuck table 6 .

A camera 42 for photographing the front surface 11 a side or the back surface 11 b side of the workpiece 11 is provided at a position adjacent to the laser irradiation unit 40 . An image formed by capturing the workpiece 11 or the like with the camera 42 is used, for example, when adjusting the position between the workpiece 11 and the laser irradiation unit 40 or the like.

Components such as the chuck table 6 , the horizontal movement mechanism 8 , the laser irradiation unit 40 , and the camera 42 are connected to a control unit (not shown). The control unit controls each component so that the workpiece 11 is appropriately processed.

Fig. 3(A) is a cross-sectional view for explaining the holding step. In addition, in FIG.3(A), a part of structural elements are shown as functional blocks. In the holding step, as shown in FIG. 3(A) , for example, the back surface 11 b of the workpiece 11 is brought into contact with the holding surface 6 a of the chuck table 6 . Next, the valve member 32 is opened so that the negative pressure of the suction source 34 acts on the holding surface 6a.

Thereby, the workpiece 11 is sucked and held on the chuck table 6 in a state in which the front surface 11a side is exposed upward. In addition, in this embodiment, as shown in FIG.3(A), the back surface 11b side of the workpiece|work 11 is hold|maintained by the chuck table 6 directly. That is, in this embodiment, the expansion sheet does not need to be attached to the workpiece 11 .

After the holding step, the first laser processing step and the second laser processing step are performed to irradiate the laser beam 17 with a wavelength having penetrability to the workpiece 11 to form a modified layer along the planned dividing line 13 . In addition, in this embodiment, the case where a 2nd laser processing step is performed after a 1st laser processing step is demonstrated.

FIG. 3(B) is a cross-sectional view for explaining the first laser processing step and the second laser processing step, and FIG. 4(A) schematically shows the workpiece 11 after forming the modified layer along all the planned dividing lines 13 of state, FIG. 4(B) is a cross-sectional view schematically showing the formation of the modified layer along each planned dividing line 13 . In addition, in FIG.3(B), a part of structural elements are shown as functional blocks.

In the first laser processing step, first, the chuck table 6 is rotated so that, for example, the extending direction of the target dividing line 13 is parallel to the X-axis direction. Next, the chuck table 6 is moved, and the position of the laser irradiation unit 40 is aligned on the extension line of the target dividing line 13 . Next, as shown in FIG. 3(B) , the chuck table 6 is moved in the X-axis direction (that is, the extending direction of the target dividing line 13 ).

Then, when the laser unit 40 reaches two points that exist on the intended dividing line 13 to be targeted, and just above one boundary between the wafer area 11c and the peripheral remaining area 11d, the laser irradiates the unit 40 from then on. The irradiation of the laser beam 17 is started. In this embodiment, as shown in FIG. 3(B) , the laser beam 17 is irradiated toward the surface 11 a of the workpiece 11 from the laser irradiation unit 40 disposed above the workpiece 11 .

The irradiation of the laser beam 17 is continued until the laser irradiation unit 40 reaches two locations on the target dividing line 13 directly above the other boundary between the wafer area 11c and the peripheral remaining area 11d. That is, here, the laser beam 17 is irradiated only in the wafer region 11c along the line 13 to be divided into the object.

Moreover, this laser beam 17 is irradiated so that a condensing point may be located in the 1st depth position from the front surface 11a (or back surface 11b) inside the workpiece|work 11. In this way, by condensing the laser beam 17 having a wavelength penetrating to the workpiece 11 inside the workpiece 11 , a part of the workpiece 11 can be modified by multiphoton absorption at the condensing point and its vicinity, and formed into a split The modified layer 19 (first modified layer 19a) at the starting point (first modified layer forming step).

In the first laser processing step of the present embodiment, since the laser beam 17 is irradiated only in the wafer region 11c along the line to be divided 13 of the object, only the wafer region is irradiated along the line to be divided 13 of the object A modified layer 19 (first modified layer 19a) is formed in 11c. That is, as shown in FIG. 4(B), in the first laser processing step, the modified layer 19 (the first modified layer 19a) is not formed in the remaining outer peripheral region 11d.

After the above-described first laser processing step, a second laser processing step is performed, and the modified layer 19 is formed at a depth position different from the first depth along the same planned dividing line 13 . Again. In the stage where the first laser processing step is completed, since the laser unit 40 exists on the extension line of the target dividing line 13 , it is not necessary to adjust the alignment of the laser irradiating unit 40 to the dividing line 13 .

In the second laser processing step, first, the chuck table 6 is moved in the X-axis direction (the direction in which the intended dividing line 13 of the object extends). Next, after the laser irradiation unit 40 reaches the outside of the workpiece 11 set The laser irradiation unit 40 starts irradiation of the laser beam 17 at a time point just above the irradiation start point of the peripheral remaining region 11 d.

In the present embodiment, as in the first laser processing step, the laser beam 17 is irradiated toward the surface 11 a of the workpiece 11 from the laser irradiation unit 40 arranged above the workpiece 11 . The irradiation of the laser beam 17 is continued until the laser irradiation unit 40 passes over the wafer region 11c of the workpiece 11 and reaches just above the irradiation end point set in the outer peripheral remaining region 11d.

That is, here, the laser beam 17 is irradiated to a part of the outer peripheral remaining region 11d and the wafer region 11c along the intended dividing line 13 of the object. In addition, the laser beam 17 is irradiated so that the condensing point is positioned at the second depth (depth different from the first depth) from the front surface 11 a (or the back surface 11 b ) inside the workpiece 11 .

Thereby, the modified layer 19 (the first modified layer 19 a ) formed in the first laser processing step can be formed at the second depth position along the planned dividing line 13 and at the end of the remaining outer peripheral region 11 d The superimposed modified layer 19 (second modified layer 19b) (second modified layer forming step). After the modified layer 19 (second modified layer 19b) is formed at the second depth position, the modified layer 19 (third modified layer 19) is formed at a third depth position different from the first depth and the second depth by the same procedure. layer 19c) (third modified layer formation step). When the modified layer 19 is formed at the third depth position, the positions of the irradiation start point and the irradiation end point can be changed.

Furthermore, in the present embodiment, one modified layer 19 (first modified layer 19 a ) is formed along one planned dividing line 13 in the first laser processing step, and in the second laser processing step Although two modified layers 19 (the second modified layer 19b and the third modified layer 19c) are formed along the same planned dividing line 13, the modified layers 19 formed along one planned dividing line 13 are: The number, location, etc. thereof are not particularly limited.

For example, the number of modified layers 19 formed along one planned dividing line 13 in the first laser processing step may be two or more. In addition, the number of the modified layers 19 formed along the same one planned dividing line 13 in the second laser processing step may be one layer, or three or more layers. That is, one or more modified layers 19 can be formed along one planned dividing line 13 in at least the first laser processing step, and can be formed along one planned dividing line 13 in the second laser processing step. One or more modified layers 19 may be used.

In addition, the modified layer 19 is preferably formed in such a condition that the cracks reach the front surface 11a (or the back surface 11b). Of course, the modified layer 19 may be formed under the conditions that the cracks reach both the front surface 11a and the surface 11b. Thereby, the workpiece 11 can be more appropriately divided.

In the case where the workpiece 11 is a silicon wafer, for example, the modified layer 19 is formed under the following conditions.

Workpiece: Silicon Wafer

Laser beam wavelength: 1340nm

Laser beam repetition rate: 90kHz

Laser beam output: 0.1W~2W

The moving speed of the chuck table (processing feed speed): 180mm/s~1000mm/s, the representative is 500mm/s

When the workpiece 11 is a gallium arsenide substrate or an indium phosphide substrate, for example, the modified layer 19 is formed under the following conditions.

Workpiece: Gallium Arsenide Substrate, Indium Phosphide Substrate

Laser beam wavelength: 1064nm

Laser beam repetition rate: 20kHz

Laser beam output: 0.1W~2W

The moving speed of the chuck table (processing feed speed): 100mm/s~400mm/s, the representative is 200mm/s

When the workpiece 11 is a sapphire substrate, for example, the modified layer 19 is formed under the following conditions.

Workpiece: Sapphire substrate

Laser beam wavelength: 1045nm

Laser beam repetition rate: 100kHz

Laser beam output: 0.1W~2W

The moving speed of the chuck table (processing feed speed): 400mm/s~800mm/s, the representative is 500mm/s

When the workpiece 11 is a ferroelectric substrate composed of a ferroelectric such as tantalum lithium acid or niobate lithium acid, for example, the modified layer 19 is formed under the following conditions.

Workpiece: tantalum lithium acid substrate, niobate lithium acid substrate

Laser beam wavelength: 532nm

Laser beam repetition rate: 15kHz

Laser beam output: 0.02W~0.2W

The moving speed of the chuck table (processing feed speed): 270mm/s~420mm/s, the representative is 300mm/s

In the case where the workpiece 11 is a glass substrate composed of soda glass, borosilicate glass, quartz glass, or the like, the modified layer 19 is formed under the following conditions, for example.

Workpiece: soda glass substrate, borosilicate glass substrate, quartz glass substrate

Laser beam wavelength: 532nm

Laser beam repetition rate: 50kHz

Laser beam output: 0.1W~2W

The moving speed of the chuck table (processing feed speed): 300mm/s~600mm/s, the representative is 400mm/s

When the workpiece 11 is a gallium nitride substrate, for example, the modified layer 19 is formed under the following conditions.

Workpiece: Gallium Nitride Substrate

Laser beam wavelength: 532nm

Laser beam repetition rate: 25kHz

Laser beam output: 0.02W~0.2W

The moving speed of the chuck table (processing feed speed): 90mm/s~600mm/s, the representative is 150mm/s

In the case where the workpiece 11 is a silicon carbide substrate, for example, the modified layer 19 is formed under the following conditions.

Workpiece: Silicon carbide substrate

Laser beam wavelength: 532nm

Laser beam repetition rate: 25kHz

Laser beam output: 0.02W~0.2W, representatively 0.1W

The moving speed of the chuck table (processing feed speed): 90mm/s~600mm/s, typically, in The cleavage direction of the silicon carbide substrate is 90mm/s, and the non-cleavage direction is 400mm/s

After the modified layer 19 is formed along the target dividing line 13 , the above-described first laser processing step and second laser processing step are repeated for all the remaining planned dividing lines 13 . Thereby, as shown in FIG. 4(A) , the modified layer 19 can be formed along all the lines to be divided 13 .

In the first laser processing step of the present embodiment, since the modified layer 19 (first modified layer 19a) is formed only in the wafer region 11c along the planned dividing line 13, and is not formed in the outer peripheral remaining region 11d The modified layer 19 (the first modified layer 19a) maintains the strength of the workpiece 11 through the remaining peripheral region 11d. Thereby, there is no problem that the workpiece 11 is divided into individual wafers due to the application of force during conveyance or the like. In this way, the remaining peripheral region 11d after the first laser processing step functions as a reinforcing portion for reinforcing the wafer region 11c.

In addition, in the first laser processing step of the present embodiment, since the modified layer 19 (first modified layer 19 a ) is not formed in the remaining outer peripheral region 11 d , for example, even if a crack extended from the modified layer 19 reaches When both the front surface 11a and the back surface 11b are completely divided and the workpiece 11 is completely divided, each wafer is also Does not fall off or scatter. Generally, when the modified layer 19 is formed on the workpiece 11 , the workpiece 11 will expand in the vicinity of the modified layer 19 . In the present embodiment, the expansion force generated by the formation of the reformed layer 19 acts inward in the annular outer peripheral remaining region 11d functioning as a reinforcing portion, thereby pressing the wafers and preventing them from falling off and scattering.

After the first laser processing step and the second laser processing step, an unloading step is performed, and the workpiece 11 is unloaded from the chuck table 6 . Specifically, for example, after the entire front surface 11a of the workpiece 11 is sucked by a transfer unit (not shown) capable of sucking and holding the entire front surface 11a (or rear surface 11b) of the workpiece 11, the valve 32 is closed to cut off the negative side of the suction source 34. Press to carry out the workpiece 11 . Furthermore, in the present embodiment, as described above, since the remaining outer peripheral region 11d functions as a reinforcing portion, there is no possibility that the workpiece 11 cannot be divided into individual wafers by force applied during conveyance or the like. The question of proper handling.

After the unloading step, a reinforcing portion removing step is performed to remove the reinforcing portion from the workpiece 11 . 5(A) and 5(B) are cross-sectional views for explaining the step of removing the reinforcement portion. In addition, in FIG.5(A) and FIG.5(B), a part of structural elements are shown as functional blocks. The step of removing the reinforcement portion is performed using, for example, the dividing device 52 shown in FIGS. 5(A) and 5(B).

The dividing device 52 includes a chuck table (holding table) 54 for sucking and holding the workpiece 11 . A part of the upper surface of the chuck table 54 serves as a holding surface 54a for attracting and holding the wafer region 11c of the workpiece 11 . The holding surface 54a is connected to the suction source 58 through a suction path 54b formed in the chuck table 54, a valve member 56, and the like. Further, a heater (heating unit) 54c is arranged below the holding surface 54a.

Another part of the upper surface of the chuck table 54 is opened with one end of the suction path 54d for sucking and holding the remaining outer peripheral region 11d of the workpiece 11 (that is, the reinforcing portion). The other end side of the suction passage 54d is connected to the suction source 58 through the valve member 60 or the like. The chuck table 54 is connected to a rotational drive source (not shown) such as a motor, and rotates around a rotational axis substantially parallel to the vertical direction.

The cutting unit 62 is arranged above the chuck table 54 . The cutting unit 62 is provided with a main shaft 64 and is a rotational axis that is substantially parallel to the holding surface 54a. An annular cutting blade 66 in which abrasive grains are dispersed in a binder is attached to one end side of the main shaft 64 .

A rotational drive source (not shown) such as a motor is connected to the other end side of the main shaft 64 , and the cutting blade 66 attached to one end side of the main shaft 64 is rotated by the force transmitted from the rotational drive source. The cutting unit 62 is supported by, for example, a lift mechanism (not shown), and the cutting blade 66 is moved in the vertical direction through the lift mechanism.

Furthermore, on the upper surface of the chuck table 54, at a position corresponding to the boundary between the wafer area 11c of the workpiece 11 and the outer peripheral remaining area 11d, an undercut for a dicing blade (not shown) is formed for preventing and dicing. Contact of the blade 66 .

In the reinforcement portion removing step, first, the back surface 11 b of the workpiece 11 is brought into contact with the holding surface 54 a of the chuck table 54 . Next, the valves 56 and 60 are opened, and the negative pressure of the suction source 58 is applied to the holding surface 54a and the like. Thereby, the workpiece 11 is sucked and held on the chuck table 54 in a state where the front surface 11a side is exposed upward. In addition, in this embodiment, as shown to FIG. 5(A), the back surface 11b side of the workpiece|work 11 is hold|maintained by the chuck table 54 directly. That is, it is not necessary to stick the expansion sheet to the workpiece 11 here.

Next, the dicing blade 66 is rotated to cut into the boundary between the wafer region 11c of the workpiece 11 and the remaining outer peripheral region 11d. At the same time, as shown in FIG. 5(A) , the chuck table 54 is rotated around a rotation axis substantially parallel to the vertical direction. Thereby, the workpiece 11 can be cut along the boundary between the wafer region 11c and the outer peripheral remaining region 11d.

Then, the valve member 60 is closed, and the negative pressure of the suction source 58 to the remaining peripheral region 11d of the workpiece 11 is cut off. Next, as shown in FIG. 5(B) , the remaining peripheral region 11 d is removed from the chuck table 54 . As a result, only the wafer region 11 c of the workpiece 11 remains on the chuck table 54 .

After the reinforcing portion removing step, a dividing step is performed to divide the workpiece 11 into individual wafers. Specifically, the workpiece 11 is divided by generating stress by heating and cooling. FIG. 6 is a cross-sectional view for explaining the dividing step. In addition, in FIG. 6, some constituent elements are shown as functional blocks.

The dividing step is carried out using successive dividing means 52 . As shown in FIG. 6 , the dividing device 52 further includes a nozzle (cooling unit) 68 arranged above the chuck table 54 . In the dividing step of the present embodiment, after the workpiece 11 is heated by the heater 54c provided on the chuck table 54, the workpiece 11 is cooled by the cooling fluid 21 supplied from the nozzle 68, and the stress necessary for dividing the workpiece 11 is generated. .

As the cooling fluid 21, for example, a liquid such as water, or a gas such as air can be used. When a liquid is used as the fluid 21, it can be cooled in advance to a low temperature (for example, a temperature higher than the freezing point of 0.1°C to 10°C) such that the liquid does not freeze. However, the type, flow rate, temperature, etc. of the fluid 21 are not particularly limited. For example, a low-temperature liquid such as liquid nitrogen can also be used, and it is possible to take more heat away through vaporization.

After the heater 54 c is operated to heat the workpiece 11 , when the cooling fluid 21 is supplied from the nozzle 68 to cool the workpiece 11 , the cracks 23 extend from the modified layer 19 through the stress generated in the workpiece 11 . Thereby, the workpiece 11 is divided into a plurality of wafers 25 along the line 13 to be divided.

The heating and cooling conditions (temperature, time, etc.) are set according to the type of the workpiece 11 and the like. Further, heating of the workpiece 11 by the heater 54c and cooling of the workpiece 11 by the liquid 21 supplied from the nozzle 68 are preferably repeated until the workpiece 11 is appropriately divided.

As described above, in the present embodiment, the workpiece 11 can be divided into the individual wafers 25 by applying the necessary force through heating and cooling. In addition, in this embodiment, although the workpiece 11 is heated and then cooled, the workpiece 11 may be cooled and then heated. The method of heating and cooling is also not particularly limited.

As described above, in the wafer manufacturing method according to the present embodiment, in a state in which the workpiece (object) 11 is directly held by the chuck table (holding table) 6, the light-converging point is positioned at the first depth position, only The laser beam 17 is irradiated on the wafer region 11c of the workpiece 11, and the modified layer 19 (the first modified layer 19a) is formed along the line 13 to be divided in the wafer region 11c, and the focusing point is positioned at the second depth position. and the third depth position is irradiated with the laser beam 17 to form a modified layer 19 which is longer than the modified layer 19 formed at the first depth position and overlaps the end of the outer peripheral remaining region 11d along the planned dividing line 13 After (the second modified layer 19b and the third modified layer 19c), since the workpiece 11 is divided into the individual wafers 25 by applying force by heating and cooling, there is no need to apply force to the workpiece 11 to separate the individual wafers. 25 expansion sheets. In this way, according to the wafer manufacturing method of the present embodiment, the silicon wafer of the plate-shaped workpiece 11 can be divided without using an expansion sheet to manufacture a plurality of chips 25 .

Further, in the wafer manufacturing method according to the present embodiment, the modified layer 19 (the first modified layer 19 a ) along the planned dividing line 13 is formed by irradiating only the wafer region 11 c of the workpiece 11 with the laser beam 17 . The outer peripheral remaining region 11d serves as a reinforcing portion in which the reformed layer 19 is not formed, and thus the wafer region 11c is reinforced through this reinforcing portion. Therefore, there is no problem that the workpiece 11 cannot be properly transported by dividing the workpiece 11 into the individual wafers 25 due to a force applied at the time of transportation or the like.

In addition, this invention is not limited to the description of the said embodiment etc., Various changes are possible and it can implement. For example, in the above-described embodiment, the second laser processing step is performed after the first laser processing step, but the first laser processing step may be performed after the second laser processing step. Further, the order of the second modified layer forming step for forming the second modified layer 19b and the order of the third modified layer forming step for forming the third modified layer 19c may be replaced.

In addition, in the above-mentioned embodiment, after the first laser processing step is performed on the line to be divided 13 of the object, the second laser processing step is performed on the same line to be divided 13, but the present invention is not limited to this state. For example, in the first step of forming the first modified layer 19 a on the plurality of planned dividing lines 13 After the laser processing step (the first modified layer forming step), the second laser processing step may be performed on the plurality of planned dividing lines 13 .

Furthermore, in this case, after the second laser processing step (second modified layer forming step) of forming the second modified layer 19b on the plurality of lines to be divided 13 is performed, the plurality of lines to be divided 13 may be formed. A second laser processing step (a third modified layer forming step) for forming the third modified layer 19c.

More specifically, for example, first, the first modified layer forming step is performed, and the first modified layer 19a is formed on all the planned dividing lines 13 parallel to the first direction. Next, the second modified layer forming step is performed, and the second modified layer 19b is formed on all the planned dividing lines 13 parallel to the first direction. Next, the third modified layer forming step is performed, and the third modified layer 19c is formed on all the planned dividing lines 13 parallel to the first direction.

Then, the first modified layer forming step is performed, and the first modified layer 19a is formed on all the planned dividing lines 13 parallel to the second direction different from the first direction. Next, the second modified layer forming step is performed, and the second modified layer 19b is formed on all the planned dividing lines 13 parallel to the second direction. Next, the third modified layer forming step is performed, and the third modified layer 19c is formed on all the planned dividing lines 13 parallel to the second direction.

In addition, in this case, the first laser processing step (the first modified layer forming step) can be performed after the second laser processing step (the second modified layer forming step and the third modified layer forming step) ). Similarly, the order of the second modified layer forming step for forming the second modified layer 19b and the order of the third modified layer forming step for forming the third modified layer 19c may be replaced.

In addition, in the above-described embodiment, although the rear surface 11b of the workpiece 11 is held by the chuck table 6 and the laser beam 17 is irradiated from the front surface 11a side, the front surface 11a side of the workpiece 11 may be directly held by the chuck table 6, And the laser beam 17 is irradiated from the back surface 11b side.

7 is a cross-sectional view for explaining a holding step according to a modification. In the holding step according to this modification, as shown in FIG. 7 , for example, a chuck table (holding table) 6 having an upper surface composed of a porous sheet (porous sheet) 44 may be used. It is composed of soft materials represented by resins such as polyethylene or epoxy resin.

In this chuck table 6, the upper surface 44a of the sheet 44 is used to suck and hold the front surface 11a side of the workpiece 11. As shown in FIG. Thereby, damage to the element etc. formed in the front surface 11a side can be prevented. This sheet 44 is a part of the chuck table 6 and is repeatedly used together with the main body of the chuck table 6 and the like.

However, the upper surface of the chuck table 6 is not necessarily made of the porous sheet 44 described above, and may be made of at least a soft material that does not damage components formed on the front surface 11 a side of the workpiece 11 . this In addition, it is preferable that the sheet material 44 is comprised so that attachment or detachment to the main body of the chuck table 6 can be carried out, and it can be exchanged when damaged, etc..

In addition, in the above-mentioned embodiment, although the reinforcement part removal step is performed after the carrying out step and before the dividing step, for example, it may be performed after the first laser processing step and the second laser processing step and before the carrying out step. Reinforcing part removal step. Furthermore, when the reinforcing part removing step is performed after the unloading step and before the dividing step, since it is not necessary to convey the workpiece 11 after the reinforcing part removing step, it is easy to avoid inconveniences such as making the workpiece 11 unable to be conveyed properly.

In addition, the step of removing the reinforcement portion may be omitted. In the second laser processing step of the above-described embodiment, the modified layer 19 (the second modified layer 19b and the third modified layer 19c ) overlapping the end of the remaining outer peripheral region 11d is formed along the planned dividing line 13 . Therefore, compared to the case where the modified layer 19 does not overlap with the remaining outer region 11d, the remaining outer region 11d is easier to divide. Therefore, even if the step of removing the reinforcement portion is not performed, the wafer region 11c and the remaining peripheral region 11d can be simultaneously divided in the dividing step.

Furthermore, in this case, for example, in the second laser processing step, the range for forming the modified layer 19 can be adjusted so that the distance from the outer peripheral edge of the workpiece 11 to the end of the modified layer 19 is about 2 mm to 3 mm. In addition, for example, before dividing the wafer region 11c in the dividing step, a groove serving as a dividing starting point may be formed in the reinforcing portion. FIG. 8(A) is a cross-sectional view for explaining the division step according to the modification, and FIG. 8(B) is a plan view schematically showing the state of the workpiece 11 after the division step according to the modification.

In the dividing step according to the modified example, as shown in FIGS. 8(A) and 8(B) , the dicing blade 66 is cut into the remaining outer peripheral region 11d (that is, the reinforcing portion), and a groove 11e serving as a dividing starting point is formed. This groove 11e is preferably formed along the line 13 to be divided, for example. By forming the grooves 11e in this way, the workpiece 11 can be divided for each outer peripheral remaining region 11d by thermal shock. In addition, in the division|segmentation process concerning a modification, the suction path 54d of the chuck table 54, the valve 60, etc. can be abbreviate|omitted.

In addition, the structures, methods, and the like related to the above-described embodiments and modifications can be appropriately changed and implemented without departing from the scope of the object of the present invention.

11: Workpiece (worked object)

11a: Front

11b: Back

11c: Wafer area

21: Fluid

23: Fissure

25: Wafer

52: Dividing device

54: Chuck table (holding table)

54a: Keep Face

54b: Way of Attraction

54c: heater (heating unit)

54d: Road of Attraction

56: Valves

58: Attractive Source

60: Valve parts

68: Nozzle (cooling unit)

Claims (3)

A wafer manufacturing method for manufacturing a plurality of wafers from a workpiece having a wafer region and a peripheral remaining region surrounding the wafer region, the wafer region being divided into a plurality of regions of the wafer by intersecting a plurality of predetermined dividing lines, and The method includes: a holding step of directly holding the workpiece with a holding table; and a first laser processing step of performing the holding step, positioning and holding the light-converging point of a laser beam having a wavelength that is penetrating to the workpiece on the workpiece. The first depth position inside the workpiece of the holding table is to irradiate only the wafer region of the workpiece with a laser beam along the line to divide, and then to form the first modified layer along the line to divide the wafer region. At the same time, the remaining area of the outer periphery is used as a reinforcing part without the first modified layer; in the second laser processing step, after the holding step is implemented, the laser beam with a wavelength that is penetrating to the workpiece is used. The light-converging point is positioned at a second depth position different from the first depth inside the workpiece held on the holding table, irradiates the laser beam along the planned dividing line, and is further formed along the planned dividing line a second modified layer that is longer than the first modified layer and overlapped at the end of the remaining peripheral region; The stage carries out the workpiece; and a dividing step, after the carrying out step is performed, a force is applied to the workpiece to divide the workpiece into each of the wafers, wherein in the dividing step, the force is applied by heating and cooling to divide the workpiece into the individual wafers the wafer. The wafer manufacturing method according to claim 1, wherein after the first laser processing step and the second laser processing step are performed, and before the dividing step is performed, further comprising: a reinforcing portion removing step, Remove the reinforcement. The wafer manufacturing method according to claim 1 or claim 2, wherein the upper surface of the holding table is made of a soft material, and in the holding step, the front side of the workpiece is held by the soft material.

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