JP6435140B2 - Wafer division method - Google Patents

Description

  The present invention relates to a dividing method for dividing a wafer into individual chips.

  A wafer formed by dividing a device such as an IC or an LSI on the surface by dividing lines is divided along the dividing lines to be divided into individual chips having the devices.

  As a method of dividing the wafer into individual chips, for example, a modified layer is formed inside the wafer by irradiating a laser beam having transparency to the wafer from the surface side of the wafer along the division line. There is a method of dividing a wafer into individual chips by further irradiating a laser beam along a planned division line on which a layer is formed to generate thermal stress (see, for example, Patent Document 1 below).

  In addition, after forming the modified layer inside the wafer as described above, an external force is applied by a pressing member along the division line on which the modified layer is formed, and the wafer is individually started from the modified layer. There is also a method of dividing into chips (see, for example, Patent Document 2 and Patent Document 3 below).

JP 2005-123329 A JP 2012-038867 A JP 2012-146744 A

  However, when the wafer is divided by the pressing member, when the wafer is divided into individual chips, the corners of adjacent chips may come into contact with each other, and the corners of the chips may be chipped. .

  The present invention has been made in view of the above circumstances, and an object thereof is to prevent chips from being chipped when a wafer is divided.

The present invention relates to a wafer dividing method for dividing a wafer starting from a laser processing layer formed inside by irradiating a laser beam along the scheduled dividing line of the wafer provided with the scheduled dividing line, the surface side of the wafer Alternatively, a chamfered portion forming step of forming a chamfered portion along the planned division line by irradiating one surface of the wafer by irradiating a laser beam along the planned division line from the back side, and the direction of the front and back of the wafer When irradiating a laser beam from the front side of the wafer in the chamfered portion forming step in the same state as the chamfered portion forming step, a laser beam is emitted from the front side of the wafer in the chamfered portion forming step. from back surface side of the wafer case of irradiating the incident of the laser beam having a transmission wavelength to the wafer The focal point which is focused in the interior in a state in which the same as the internal processing step and the internal processing step, the front and back direction of the wafer to form the laser processing layer is moved along the dividing lines Te, the pressing member And a dividing step of dividing the wafer from the laser processed layer as a starting point by pressing the wafer from the surface side where the chamfered portion is formed along the division line.

  The wafer dividing method according to the present invention includes a chamfered portion forming step of forming a chamfered portion along a line to be divided by ablation processing on one surface of the wafer, and forming a laser processing layer serving as a dividing starting point inside the wafer. When the wafer is divided, the internal processing step and the dividing step of pressing the wafer from the surface side where the chamfered portion is formed along the planned dividing line by the pressing member and dividing the laser processing layer as a starting point are provided. The corner portions of adjacent chips can be prevented from coming into contact with each other by the chamfered portion, and the chips after the division are not chipped.

It is a perspective view which shows an example of a wafer. It is sectional drawing which shows an internal processing process among the 1st examples of the division | segmentation method. It is sectional drawing which shows a chamfer part formation process among the 1st examples of the division | segmentation method. It is sectional drawing which shows a division | segmentation process among the 1st examples of the division | segmentation method. It is sectional drawing which shows a chamfer part formation process among the 2nd examples of the division | segmentation method. It is sectional drawing which shows an internal processing process among the 2nd examples of the division | segmentation method. It is sectional drawing which shows a division | segmentation process among the 2nd examples of the division | segmentation method.

  A wafer 1 shown in FIG. 1 is an example of a workpiece to be laser processed. On the front surface 2a of the wafer 1, devices 4 are formed in the respective regions defined by the grid-like division planned lines 3, and the device 4 is not formed on the back surface 2b opposite to the front surface 2a. Below, the division | segmentation method which divides | segments the wafer 1 into each chip | tip is demonstrated.

1 First Example Internal Processing Step of Wafer Dividing Method As shown in FIG. 2, a laser processing layer serving as a starting point for splitting inside the wafer 1 by irradiating a laser beam along a planned dividing line 3 using a laser beam irradiation means 10. Form. The laser beam irradiation means 10 includes a laser beam oscillation unit (not shown) and a condensing lens 11 for condensing the laser beam oscillated from the laser beam oscillation unit at a predetermined position inside the workpiece. The laser beam irradiation means 10 includes a position adjusting unit that adjusts the position of the condensing point of the laser beam condensed by the condensing lens 11, for example, and the position of the condensing point of the laser beam with respect to the wafer 1 is set to a desired position. Can be adjusted.

  Before performing laser processing on the wafer 1, a protective film 7 formed of a water-soluble resin is formed on the surface 2 a in order to prevent debris generated during laser irradiation from adhering to the surface 2 a of the wafer 1. It is desirable to coat it. As the protective film 7, for example, a protective film “HogoMax” which is a product provided by DISCO Corporation can be used.

  Next, after sticking the tape base material 6 to the back surface 2b of the wafer 1 via the adhesive material 5, the back surface 2b side is placed and held on a processing table, for example, and the front surface 2a side is made to face upward. Then, the wafer 1 is moved below the laser beam irradiation means 10. The laser beam irradiating means 10 is positioned above the planned division line 3, and the condensing point 11 of the laser beam is positioned inside the wafer 1 by the condensing lens 11, and is transparent to the wafer 1 along the planned division line 3. A laser beam LB1 having a wavelength is irradiated from the surface 2a side of the wafer 1. Then, by moving the laser beam irradiation means 10 and the wafer 1 relatively in the horizontal direction (the surface direction of the wafer 1), the condensing point P1 is moved along the scheduled division line 3, and laser processing is performed inside the wafer 1. Layer 8a is formed. When the laser processing layer 8a is formed by irradiating the laser beam LB along all the division lines 3 of the wafer 1, the internal processing process is completed.

Chamfered portion forming step As shown in FIG. 3, the laser beam irradiation means 10 performs ablation processing on the surface 2 a of the wafer 1 to form a chamfered portion along the scheduled division line 3. The laser beam irradiating means 10 positions the condensing point P2 of the laser beam condensed by the condensing lens 11 on the division line 3 on the surface 2a of the wafer 1, and outputs a laser beam LB2 having a wavelength that is absorptive with respect to the wafer 1. Irradiate toward the surface 2 of the wafer 1. Then, by moving the laser beam irradiation means 10 and the wafer 1 relatively in the horizontal direction, the condensing point P2 is moved along the planned division line 3, and is ablated along the planned division line 3 to be chamfered 9a. Form.

Dividing Step As shown in FIG. 4, the wafer 1 is divided by applying an external force from the upper side of the wafer 1 by the dividing blade 20 disposed on the upper side of the wafer 1. The split blade 20 is an example of a pressing member, and a tip portion thereof is formed in a line shape along the planned split line 3. This split blade 20 is positioned above the planned split line 3 of the wafer 1. Next, the dividing blade 20 is lowered in a direction approaching the surface 2 a of the wafer 1, and the wafer 1 is pressed by pushing down the surface 2 a side where the chamfered portion 9 a is formed at the tip portion of the dividing blade 20.

  When the laser processing layer 8a cannot withstand the pressing force, the wafer 1 is broken into individual chips 30 along the division line 3 starting from the laser processing layer 8a. At this time, the adjacent chips 30 approach each other with the portion pressed by the split blade 20 as the center, but as shown in the partial enlarged view of FIG. 4, the chamfered portions are provided at the corners 31 and 32 of the adjacent chips 30. Since 9a is formed, the corners 31 and 32 do not contact each other. Therefore, chipping can be prevented from occurring in the chip 30, and the quality of the chip is improved. In this way, the wafer 1 is pressed by the dividing blade 20 along all the division lines 3 to be divided into chips 30 with the devices 4. Thereafter, each chip 30 is picked up by a conveying means (not shown).

2 Second Example of Wafer Dividing Method The method of dividing the wafer 1 is not limited to the case of carrying out in the order of the steps described above, and the chamfered portion forming step may be carried out before carrying out the internal machining step. .

(1) Chamfered portion forming step As shown in FIG. 5, the surface 2a of the wafer 1a is ablated by the laser beam irradiation means 10a to form a chamfered portion along the planned dividing line 3. The laser beam irradiation means 10a has the same configuration as the laser beam irradiation means 10 described above. First, the back surface 2b of the wafer 1a is exposed upward, the tape base material 6 is adhered to the front surface 2a via the adhesive material 5, and the front surface 2a side is placed on a processing table, for example.

  Next, the wafer 1a is moved below the laser beam irradiation means 10a. The laser beam irradiating means 10a positions the condensing point P3 of the laser beam condensed by the condensing lens 11 on the planned division line 3 on the surface 2a of the wafer 1a, and the laser beam LB1 having a wavelength that is transmissive to the wafer 1a. Irradiation is performed toward the back surface 2b of the wafer 1a. Then, by moving the laser beam irradiation means 10a and the wafer 1a relatively in the horizontal direction (the surface direction of the wafer 1a), the condensing point P3 is moved along the planned division line 3, and along the planned division line 3. The chamfered portion 9b is formed on the surface 2a by ablation processing.

(2) Internal processing step As shown in FIG. 6, a laser processing layer serving as a division starting point is formed inside the wafer 1a by irradiating laser along the division line 3 using a laser beam irradiation means 10a. The laser beam irradiating means 10a positions the condensing point P4 of the laser beam inside the planned division line 3 of the wafer 1a by the condensing lens 11, and a laser beam LB1 having a wavelength that is transmissive to the wafer 1a along the planned division line 3. Is irradiated from the back surface 2b side of the wafer 1a. By moving the laser beam irradiation means 10a and the wafer 1a relatively in the horizontal direction, the condensing point P4 is moved along the planned division line 3, and the laser processing layer 8b is formed inside the wafer 1a. When the laser processing layer 8b is formed by irradiating the laser beam LB along all the division lines 3 of the wafer 1a, the internal processing process is completed.

Dividing Step As shown in FIG. 7, the dividing blade 20a disposed on the lower side of the wafer 1a applies an external force from the lower side of the wafer 1a to divide the wafer 1a. The split blade 20a is positioned below the planned split line 3 of the wafer 1a, the split blade 20a is raised in the direction approaching the surface 2a of the wafer 1a, and the surface 2a in which the chamfered portion 9b is formed at the tip portion of the split blade 20a. The side 1 is pushed up to press the wafer 1a.

  When the laser processed layer 8b cannot withstand the pressing force, the wafer 1a is broken into individual chips 30a along the planned division line 3 starting from the laser processed layer 8b. At this time, the adjacent chips 30a approach each other around the portion pressed by the dividing blade 20, but as shown in the enlarged partial view, the chamfered portions 9b are applied to the corner portions 31 and 32 of the adjacent chips 30a. Therefore, the corner portions 31 and 32 do not contact each other. Therefore, like the first example of the wafer dividing method described above, it is possible to prevent the chip 30a from being chipped, and the chip quality is improved. When the wafer 1a is pressed by the dividing blade 20a along all the planned dividing lines 3 and divided into chips 30a with the device 4, the chips 30a are picked up by a conveying means (not shown).

  The laser processed layers 8a and 8b in the illustrated example are formed inside the wafer, but the laser processed layer formed in the internal processing step is not limited to this modified layer. For example, a vertically long laser processing layer from the front surface 2a to the back surface 2b of the wafer 1 may be formed. By forming such a laser processed layer, the quality of the chip formed by the dividing step is further improved.

DESCRIPTION OF SYMBOLS 1, 1a: Wafer 2a: Front surface 2b: Back surface 3: Planned division line 4: Device 5: Adhesive material 6: Tape base material 7: Protective film 8a, 8b: Laser processing layer 9a, 9b: Chamfer 10, 10a: Laser beam Irradiation means 11: condenser lens 20, 20a: split blade 30, 30a: chip 31, 32: corner

Claims (1)

A wafer dividing method for dividing a wafer starting from a laser processing layer formed inside by irradiating a laser beam along the scheduled dividing line of the wafer having the scheduled dividing line,
A chamfered portion forming step of forming a chamfered portion along the planned dividing line by ablating one surface of the wafer by irradiating a laser beam along the planned dividing line from the front surface side or the back surface side of the wafer ;
When irradiating a laser beam from the front surface side of the wafer in the chamfered portion forming step with the front and back surfaces of the wafer being in the same direction as in the chamfered portion forming step, the wafer from the front surface side of the wafer in the chamfered portion forming step. When irradiating a laser beam from the back surface side of the wafer, a condensing point focused on the inside by making a laser beam having a wavelength transmissive to the wafer incident from the back surface side of the wafer along the division planned line An internal processing step to move and form a laser processing layer;
With the wafer front and back facing in the same direction as the internal processing step, the wafer is pressed from the surface side where the chamfered portion is formed along the planned dividing line by the pressing member, and the wafer is started from the laser processing layer. A dividing step of dividing the wafer.

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