JP2013089714A - Chip formation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chip formation method capable of dividing a workpiece into individual chips while forming the chips each at least partially having an inclined surface on its outer peripheral side surface.SOLUTION: A chip formation method for dividing a workpiece to form a plurality of chips each at least partially having an inclined surface on its outer peripheral side surface, includes: an inclined surface setting step of setting a plurality of inclined surfaces corresponding to the inclined surfaces of the chips in the workpiece; a modified layer forming step of forming a plurality of modified layers spaced from each other along the inclined surfaces by relatively moving the workpiece and a laser beam while irradiating the workpiece with the laser beam in a state in which a condensing point of the laser beam having a wavelength having transparency with respect to the workpiece is positioned in the inside of the workpiece; and a dividing step of, after execution of the modified layer forming step, dividing the workpiece along the inclined surfaces by applying external force to the workpiece and using the modified layer as a starting point, to form the plurality of chips.

Description

  The present invention relates to a chip forming method for dividing a workpiece to form a plurality of chips having inclined surfaces on at least a part of an outer peripheral side surface.

  In a semiconductor chip, an optical device chip, or the like, a chip shape having a side surface perpendicular to the surface of the chip is generally used. Such a chip is formed by cutting a semiconductor wafer or an optical device wafer along a planned division line with a cutting apparatus or a laser processing apparatus.

  However, in various optical components such as a laser lens and a camera lens, an optical component having an inclined surface on at least a part of the outer peripheral side surface of the chip is used. Conventionally, in order to form an inclined surface on the outer peripheral side surface of a chip, a workpiece is divided and a plurality of chips are formed, and then held on a chuck table, for example, as disclosed in JP-A-2003-124155. Using the cutting device having the cutting unit inclined with respect to the workpiece to be processed, the outer peripheral side surface of each chip is cut to form the inclined surface.

JP 2003-124155 A

  However, after forming a plurality of chips by dividing a workpiece, forming the inclined surface on the outer peripheral side surface of the chip using a cutting device for each chip is complicated and very inefficient. There is a problem.

  The present invention has been made in view of the above points, and an object of the present invention is to divide a workpiece into individual chips and at the same time form a chip having an inclined surface on at least a part of an outer peripheral side surface. It is to provide a possible chip forming method.

  According to the present invention, there is provided a chip forming method in which a workpiece is divided to form a plurality of chips having inclined surfaces on at least a part of an outer peripheral side surface, and the workpiece is provided with a plurality of chips corresponding to the inclined surfaces of the chips. An inclined surface setting step for setting the inclined surface of the workpiece, and the laser beam is irradiated while irradiating the laser beam in a state where the condensing point of the laser beam having a wavelength transmissive to the workpiece is positioned inside the workpiece. A modified layer forming step of forming a modified layer along the inclined surface by relatively moving an object and the laser beam, and applying the external force to the workpiece after performing the modified layer forming step A dividing step of dividing the workpiece along the inclined surface to form a plurality of chips with the modified layer as a starting point, and the modified layer forming step covers the condensing point of the laser beam. Positioned on the inclined surface at a first depth from the surface of the workpiece A first step of forming a first modified layer along the inclined surface by relatively moving the workpiece and the laser beam while irradiating the laser beam; The workpiece and the laser beam are moved relative to each other while the laser beam is irradiated on the inclined surface having a second depth different from the first depth from the surface of the workpiece. A second step of forming a second modified layer along the line, and in the dividing step, an external force is applied to the workpiece to form the first modified layer and the second modified layer. There is provided a chip forming method characterized in that a plurality of chips having inclined surfaces are formed on at least a part of an outer peripheral side surface by dividing a workpiece at a starting point.

  In the chip formation method of the present invention, after forming a plurality of modified layers on the inclined surface set on the workpiece, an external force is applied to the workpiece, and the workpiece is divided starting from the plurality of modified layers. Therefore, it is possible to efficiently and easily form a plurality of chips having inclined surfaces on at least a part of the outer peripheral side surface at the same time that the workpiece is divided into individual chips.

It is a partial perspective view of the glass substrate explaining a mode that an inclined surface is set to a glass substrate. It is a principal part perspective view of the laser processing apparatus explaining a mode that a modified layer is formed in a glass substrate by irradiation of a laser beam. It is a block diagram of a laser beam irradiation unit. It is a partial perspective view of the glass substrate in which the three modified layers were formed along the inclined surface. It is a longitudinal cross-sectional view of the dividing apparatus which shows a glass substrate division | segmentation step. It is a longitudinal cross-sectional view of the chip | tip formed by this invention embodiment. It is a longitudinal cross-sectional view of the various chip | tip which can be formed with the chip | tip formation method of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, a partially broken perspective view of a glass substrate 11 suitable for processing by the chip forming method of the present invention is shown. The glass substrate 11 has a front surface 11a and a back surface 11b. In the chip forming method of the present invention, the back surface 11b of the glass substrate 11 is attached to the adhesive tape T shown in FIG. Adhere to the annular frame F.

  Then, as shown in FIG. 2, the glass substrate 11 is sucked and held via the adhesive tape T by the chuck table 10 of the laser processing apparatus 8. The laser processing apparatus 8 includes a laser beam irradiation unit 12 that irradiates a glass substrate 11 held on the chuck table 10 with a laser beam, and a microscope and a CCD camera that image the glass substrate 11 held on the chuck table 10. The imaging unit 14 is included.

  The chuck table 10 is configured to suck and hold the glass substrate 11 via the adhesive tape T, and is moved in a processing feed direction indicated by an arrow X and an index feed direction indicated by an arrow Y by a moving mechanism (not shown).

  The laser beam irradiation unit 12 includes a laser beam generation unit 18 shown in the block diagram of FIG. 3 housed in a cylindrical casing 12 arranged substantially horizontally, and a condenser 20 attached to the tip of the casing 16. It consists of.

  The laser beam generating unit 18 includes a laser oscillator 22 such as a YAG laser oscillator or a YVO4 laser oscillator, a repetition frequency setting means 24, a pulse width adjusting means 26, and a power adjusting means 28.

  The pulsed laser beam adjusted to a predetermined power by the power adjusting means 28 of the laser beam generating unit 18 is reflected by the mirror 30 of the condenser 20 attached to the tip of the casing 16 and further collected by the condenser objective lens 32. The glass substrate 11 held by the chuck table 10 is irradiated with light.

  In the chip forming method according to the embodiment of the present invention, first, an inclined surface setting step for setting a plurality of inclined surfaces corresponding to the inclined surfaces of the chips to be formed on the glass substrate 11 as a workpiece is performed.

  In this inclined surface setting step, the glass substrate 11 held on the chuck table 10 is imaged by the imaging unit 14, and a plurality of front surface side first division planned lines 13a extending in the first direction (X-axis direction); A plurality of back side first division planned lines 13b that are separated from each front side first division planned line 13a by a predetermined distance in the Y-axis direction are set.

  Since the thickness of the glass substrate 11 is known in advance, an inclined surface 15 that is inclined by a predetermined angle including the front-side first division planned line 13a and the back-side first division planned line 13b is set. The y coordinate values of the front surface side first division planned line 13a and the back side first division planned line 13b and the inclination angle of the inclined surface 15 are stored in the memory of the controller of the laser processing apparatus 8. Next, the chuck table 10 is rotated 90 degrees to set a plurality of second scheduled division lines 17 separated by a predetermined distance, and the y coordinate value of the second scheduled division line 17 is stored in the memory.

  When the setting of the scheduled division line and the setting of the inclined surface are completed, the chuck table 10 is moved to the laser beam irradiation region where the condenser 20 of the laser beam irradiation unit 12 for irradiating the laser beam is located.

  Then, the condensing point of the laser beam having a wavelength that is transparent to the glass substrate 11 is positioned on the inclined surface 15 having the first depth from the surface 11a of the glass substrate 11 by the condenser 20, and the laser beam is irradiated. However, the first modified layer 21a is formed on the inclined surface 15 as shown in FIG. 4 by moving the chuck table 10 in the X-axis direction at a predetermined processing feed rate.

  Next, the laser beam is focused on the inclined surface 15 having a second depth different from the first depth from the surface 11a of the glass substrate 11, and the chuck table 10 is subjected to predetermined processing while irradiating the laser beam. The second modified layer 21b is formed on the inclined surface 15 by moving in the X-axis direction at the feed speed.

  Furthermore, the laser beam is focused on the inclined surface 15 having a third depth different from the second depth from the surface 11a of the glass substrate 11, and the chuck table 10 is subjected to predetermined processing while irradiating the laser beam. The third modified layer 21c is formed on the inclined surface 15 by moving in the X-axis direction at the feeding speed.

  The modified layers 21a to 21c are regions in which the density, refractive index, mechanical strength, and other physical characteristics are different from the surroundings. These modified layers 21a to 21c are formed as melt-rehardened layers.

  The processing conditions in this modified layer forming step are set as follows, for example.

Light source: LD excitation Q switch Nd: YVO 4 pulse laser Wavelength: 1064 nm
Repetition frequency: 100 kHz
Pulse output: 10μJ
Condensing spot diameter: φ1μm
Processing feed rate: 100 mm / sec

  After the modified layer forming step on the inclined surface 15 is performed on all the inclined surfaces 15, the chuck table 10 is rotated by 90 degrees, and the condensing point of the laser beam is positioned inside the glass substrate 11. While irradiating the laser beam along the second division planned line 17 in the state, the chuck table 10 is moved in the X-axis direction at a predetermined processing feed rate, and the inside of the glass substrate 11 along the second division planned line 17 A modified layer is formed on the substrate.

  The reformed layer along the second scheduled division line 17 may be formed as a single layer, but it is preferable to form a plurality of layers at different depths. In the above-described embodiment, the first to third modified layers 21a to 21c are formed along the inclined surface 15. However, the formation of the modified layer on the inclined surface 15 is limited to three layers. Instead, two or more layers may be formed separated by a predetermined distance. In the case of forming a plurality of layers, preferably, the layers are formed in order from the modified layer farthest from the laser incident surface. Thereby, the laser beam is not disturbed by the modified layer already formed.

  After performing the modified layer forming step, the dividing step of dividing the glass substrate 11 to form a plurality of chips 23 by the dividing device 40 as shown in FIG. 5A, the dividing device 40 includes a frame holding unit 42 that holds the annular frame F, and an expansion drum 44 that extends the adhesive tape T attached to the annular frame F held by the frame holding unit 42. ing.

  The frame holding unit 40 includes an annular frame holding member 46 and a plurality of clamps 48 as fixing means disposed on the outer periphery of the frame holding member 46. The upper surface of the frame holding member 46 forms a mounting surface 46a on which the annular frame F is placed, and the annular frame F is placed on the mounting surface 46a.

  The frame holding unit 42 is configured so that the driving means 50 including the air cylinder 52 causes the annular frame holding member 46 to have a reference position where the mounting surface 46a is substantially flush with the upper end of the expansion drum 44, and the expansion drum 44. It moves in the vertical direction between the extended positions below the upper end by a predetermined amount. A piston rod 54 of the air cylinder 52 is connected to the lower surface of the frame holding member 46.

  In the dividing step, as shown in FIG. 5A, the annular frame F that supports the glass substrate 11 via the adhesive tape T is placed on the placement surface 46 a of the frame holding member 46, and the frame is clamped by the clamp 48. The holding member 46 is fixed. At this time, the frame holding member 46 is positioned at a reference position where the mounting surface 46 a is substantially at the same height as the upper end of the expansion drum 44.

  Next, the air cylinder 52 is driven to lower the frame holding member 46 to the extended position shown in FIG. As a result, the annular frame F fixed on the mounting surface 46a of the frame holding member 46 is also lowered, so that the adhesive tape T attached to the annular frame F abuts on the upper end edge of the expansion drum 44 and mainly has a radius. Expanded in the direction.

  As a result, a tensile force acts radially on the glass substrate 11 attached to the adhesive tape T. Thus, when a tensile force acts radially on the glass substrate 11, the modified layers 21 a to 21 c formed on the inclined surface 15 and the modified layer formed inside the glass substrate along the second scheduled division line 17 are strong. Therefore, the glass substrate 11 is broken along the modified layers 21a to 21c with the modified layers 21a to 21c as the starting point of the division, and the chip as shown in FIG. It is divided into 23.

  In the chip forming method of the present invention, not only the chip 23 having a parallelogram-shaped longitudinal section having the inclined surface 15 on the side surface as shown in FIG. 6, but also shown in, for example, FIGS. 7 (A) to 7 (C). Such chips 23 </ b> A to 23 </ b> C having inclined surfaces on at least a part of the outer peripheral side surface can be formed.

  In the above-described embodiment, the example in which the chip forming method of the present invention is applied to the glass substrate 11 has been described. However, the workpiece is not limited to the glass substrate, and a semiconductor wafer having a device on the surface, an optical device wafer, or the like. It can be similarly applied to.

DESCRIPTION OF SYMBOLS 10 Chuck table 11 Glass substrate 12 Laser beam irradiation unit 13a Front side 1st division | segmentation scheduled line 13b Back side 1st division | segmentation scheduled line 14 Imaging unit 15 Inclined surface 17 2nd division | segmentation line 18 Laser beam generation unit 20 Condenser 40 Division | segmentation Device 42 Frame holding unit 44 Expansion drum 52 Air cylinder T Adhesive tape F Annular frame

Claims (1)

A chip forming method for dividing a workpiece to form a plurality of chips having inclined surfaces on at least a part of an outer peripheral side surface,
An inclined surface setting step for setting a plurality of inclined surfaces corresponding to the inclined surface of the chip on the workpiece;
While irradiating the laser beam with the condensing point of the laser beam having a wavelength transmissive to the workpiece positioned inside the workpiece, the workpiece and the laser beam are moved relative to each other to move the laser beam. A modified layer forming step of forming a modified layer along the inclined surface;
A step of dividing the workpiece along the inclined surface by applying an external force to the workpiece and dividing the workpiece along the inclined surface to form a plurality of chips after performing the modified layer forming step; Equipped,
The modified layer forming step includes:
The laser beam is irradiated with the laser beam focusing point positioned on the inclined surface having a first depth from the surface of the workpiece, and the workpiece and the laser beam are moved relative to each other to incline the laser beam. A first step of forming a first modified layer along the surface;
The work piece and the laser beam are irradiated while irradiating the laser beam with the focal point of the laser beam being positioned on the inclined surface having a second depth different from the first depth from the surface of the work piece. At least a second step of forming a second modified layer along the inclined surface by relatively moving
In the dividing step, an inclined surface is formed on at least a part of the outer peripheral side surface by applying an external force to the workpiece to divide the workpiece from the first modified layer and the second modified layer. A method for forming a chip, comprising forming a plurality of chips.

Images