KR101160200B1 - Method for Dividing Wafers - Google Patents

Abstract

The present invention provides a method of dividing a wafer which can form and maintain a predetermined gap between the divided chips by extending the holding tape with the wafers formed with reduced strength along the dividing line and applying a tensile force to the wafer. .

Dividing a wafer in which a plurality of scheduled division lines are formed in a lattice shape on the surface, and a wafer in which functional elements are formed in a plurality of regions partitioned along a plurality of scheduled division lines is divided into individual chips along a scheduled division line. A method of forming a deformed layer in which a laser beam having transparency to a wafer is irradiated along a dividing line and forming an altered layer in the inside of the wafer along a dividing line, and the adhesive tape having a larger area than the wafer. Adhesive tape adhering process, tape expansion process for expanding the adhesive tape with wafer, dividing the wafer into individual chips along the scheduled division line where the deterioration layer is formed, and forming gaps between the chips. Ringed back to surround the wafer divided into individual chips with the adhesive tape extended And a frame bonding process for attaching the positive frame to the adhesive tape.

Scheduled line, wafer, adhesive tape

Description

Method for Dividing Wafers

1 is a perspective view of a semiconductor wafer divided into individual chips according to the wafer splitting method according to the present invention.

2 is a perspective view of a main part of a laser processing apparatus for performing a deterioration layer forming step in the wafer dividing method according to the present invention.

FIG. 3 is a block diagram briefly showing the configuration of laser beam irradiation means attached to the laser processing apparatus shown in FIG. 2.

4 is a simplified diagram for explaining a condensed spot diameter of a pulsed laser beam.

5 is an explanatory diagram of a deterioration layer forming process in the wafer dividing method according to the present invention.

6 is an explanatory diagram of an adhesive tape bonding process in the wafer dividing method according to the present invention.

7 is an explanatory diagram for a tape expansion step in the wafer dividing method according to the present invention.

8 is an explanatory view of a frame bonding process in the wafer dividing method according to the present invention.

9 is a perspective view showing a state in which a wafer divided into individual chips is supported in a ring-shaped frame through an adhesive tape according to a method of dividing a wafer according to the present invention.

** Description of Major Reference Codes **

2: laser processing apparatus 21: chuck table of laser processing apparatus

22: laser beam irradiation means 23: imaging means

3: adhesive tape 4: holding member

5: annular frame 10: semiconductor wafer

101: scheduled division line 102: circuit

110: altered layer 100: semiconductor chip

According to an embodiment of the present invention, a wafer in which a plurality of division lines are formed in a lattice shape on a surface thereof, and functional elements are formed in a plurality of regions partitioned along the plurality of division lines, are divided into individual chips along the division lines. A wafer dividing method for dividing.

In the semiconductor device manufacturing process, a plurality of regions are partitioned along a division scheduled line called streets arranged in a lattice shape on the surface of a semiconductor wafer having a substantially disk shape, and circuits such as IC and LSI are formed in the partitioned region. Subsequently, the semiconductor wafer is cut along the scheduled division lines to divide regions where circuits are formed to manufacture individual semiconductor chips. In addition, an optical device wafer in which a gallium nitride compound semiconductor or the like is laminated on a surface of a sapphire substrate is also cut along a predetermined scheduled line to be divided into optical devices such as individual light emitting diodes and laser diodes, which are widely used in electrical equipment. have.

Cutting along the scheduled dividing line of the semiconductor wafer, optical device wafer, and the like described above is performed by a cutting apparatus called a dicer. The cutting device includes a chuck table for holding a workpiece such as a semiconductor wafer or an optical device wafer, cutting means for cutting the workpiece held in the chuck table, and cutting transfer means for relatively moving the chuck table and the cutting means. Equipped with. The cutting means includes a rotating spindle, a cutting blade mounted to the spindle, and a driving mechanism for rotating the rotating spindle. The cutting blade is composed of a disk-shaped base and a ring-shaped cutting edge mounted on the side outer periphery of the base, and the cutting edge is fixed to the base by, for example, diamond grinding particles having a particle diameter of about 3 μm. 20 micrometers in thickness is formed.

By the way, since a sapphire board | substrate, a silicon carbide board | substrate, etc. have high Mohs hardness, cutting | disconnection by the said cutting blade is not necessarily easy. In addition, since the cutting blade has a thickness of about 20 µm, a width of about 50 µm is required as a division scheduled line for dividing the device. For this reason, for example, in the case of a device having a size of about 300 μm × 300 μm, the area ratio occupied by the street may be 14%, resulting in poor productivity.

On the other hand, as a method of dividing a workpiece in the form of a plate such as a semiconductor wafer in recent years, a pulsed laser beam is irradiated with a focusing point inside the region to be divided by using a pulsed laser beam having transparency to the workpiece. Laser processing methods have also been tried. In the division method using this laser processing method, a pulsed laser beam of an infrared ray region having a permeability with respect to a workpiece is irradiated by aligning a focusing point from one side of the workpiece to the inside, and a scheduled division line is formed inside the workpiece. The altered layer is subsequently formed, and the altered layer is formed so as to divide the workpiece by applying an external pressure along a division scheduled line whose strength has decreased (for example, Japanese Patent No. 3408805).

As described above, a method of dividing a wafer into individual chips by applying an external pressure along a dividing line of a wafer on which a deterioration layer is continuously formed along a dividing line is provided. By applying a tensile force to the wafer, a technique of dividing the wafer into individual chips along a division scheduled line on which the deterioration layer is formed is proposed as Japanese Patent Application No. 2003-361471.

In the method of dividing the wafer into individual chips, the wafer is divided into individual chips in the method of dividing the wafer into individual chips by extending the retaining tape with the wafers formed with reduced strength along the dividing line. If the tension is released afterwards, there is a problem that the extended retaining tape shrinks and the chips are in contact with each other during conveyance and the chips are damaged.

SUMMARY OF THE INVENTION The present invention has been made in view of the above facts, and its main technical problem is to extend a holding tape with a wafer formed with a reduced strength along a scheduled division line to give a tensile force to the wafer, thereby providing a predetermined gap between the individual chips. It is to provide a method of dividing the wafer that can be formed and maintained.

In order to solve the main technical problem, according to the present invention, a plurality of divided scheduled lines are formed on the surface in a lattice shape, and a wafer having functional elements formed in a plurality of regions partitioned along the plurality of divided scheduled lines is provided. As a division method of a wafer to be divided into individual chips according to the division schedule line,

A deterioration layer forming process of irradiating a laser beam having transparency to the wafer along the predetermined dividing line to form a deteriorated layer along the predetermined dividing line in the wafer;

An adhesive tape adhering step of adhering the wafer to the adhesive tape having a larger area than the wafer before or after the deforming layer forming step;

A tape expansion step of dividing the adhesive tape to which the wafer is attached and dividing the wafer into individual chips along the scheduled division line on which the deterioration layer is formed, and forming a gap between the chips;

And a frame bonding step of attaching a ring-shaped frame to the adhesive tape so as to surround the wafer divided into the individual chips in a state in which the adhesive tape is expanded after the tape expanding process. This is provided.

Best Mode for Carrying Out the Invention Preferred embodiments of the wafer dividing method according to the present invention will now be described in detail with reference to the accompanying drawings.

1 shows a perspective view of a semiconductor wafer as a wafer divided into individual chips in accordance with the present invention. The semiconductor wafer 10 shown in FIG. 1 is made of a silicon wafer, and a plurality of scheduled division lines 101 are formed in a lattice shape on the surface 10a. Then, a circuit 102 as a functional element is formed on the surface 10a of the semiconductor wafer 10 in a plurality of regions partitioned along the plurality of division lines 101. Hereinafter, an embodiment of the division method for dividing the semiconductor wafer 10 into individual semiconductor chips will be described.

In order to divide the semiconductor wafer 10 into individual semiconductor chips, a pulsed laser beam having transparency to the semiconductor wafer 10 is irradiated along the dividing scheduled line 101, and the dividing semiconductor wafer 10 is to be divided into the semiconductor wafer 10. By forming a deterioration layer along the line 101, a deterioration layer forming process of lowering the strength along the scheduled division line is performed.

This altered layer forming step is performed using the laser processing apparatus 2 shown in FIGS. 2 to 4. The laser processing apparatus 2 shown to FIG. 2 thru | or 4 is the chuck table 21 which hold | maintains a to-be-processed object, and the laser beam irradiation means 22 which irradiates a laser beam to the workpiece | work hold | maintained on the said chuck table 21. And an imaging means 23 for imaging the workpiece held on the chuck table 21. The chuck table 21 is configured to suck and hold the workpiece, and is moved in the machining feed direction indicated by the arrow X in FIG. 2 and the divided transfer direction indicated by the arrow Y by a moving mechanism (not shown).

The laser beam irradiation means 22 comprises a cylindrical casing 221 arranged substantially horizontally. In the casing 221, as shown in FIG. 3, the pulse laser beam oscillation means 222 and the transmission optical system 223 are provided. The pulsed laser beam oscillation means 222 is comprised by the pulsed laser beam oscillator 222a which consists of a YAG laser oscillator or a YVO4 laser oscillator, and the repetition frequency setting means 222b provided with this. The transmission optical system 223 includes suitable optical elements such as beam splitters. At the distal end of the casing 221, a condenser 224 containing a condenser lens (not shown) composed of a lens assembly which is itself well known is mounted. The laser beam oscillated from the pulsed laser beam oscillating means 222 reaches the condenser 224 through the transmission optical system 223, and a predetermined condensing spot is collected from the condenser 224 to the workpiece held in the chuck table 21. Irradiated at diameter D. As shown in Fig. 4, the condensing spot diameter D is D (μm) = 4 × λ × f / when a pulsed laser beam showing a Gaussian distribution is irradiated through the objective lens 224a of the condenser 224. (π × W) (where λ is the wavelength of the pulsed laser beam (μm), W is the diameter of the pulsed laser beam incident on the objective lens 224a (mm), and f is the focal length (mm) of the objective lens 224a) It is prescribed by)).

The imaging means 23 attached to the distal end of the casing 221 constituting the laser beam irradiation means 12 is, in the illustrated embodiment, in addition to a normal imaging device (CCD) for imaging with visible light. It consists of an infrared illuminating means for irradiating infrared rays, an optical system for catching infrared rays irradiated by the infrared illuminating means, and an imaging device (infrared CCD) for outputting an electric signal corresponding to the infrared rays captured by the optical system, and the like. One image signal is sent to the control means described later.

The deterioration layer forming process performed using the laser processing apparatus 2 described above will be described with reference to FIGS. 2 and 5.

In this altered layer forming step, the semiconductor wafer 10 is placed on the chuck table 21 of the laser processing apparatus 2 shown in FIG. 2 described above with the rear surface 10b facing up, and the semiconductor wafer is placed on the chuck table 21. Holds 10 by adsorption. The chuck table 21 suction-holding the semiconductor wafer 10 is located directly under the imaging means 23 by a moving mechanism not shown.

When the chuck table 21 is located directly under the imaging means 23, the alignment operation for detecting the machining area of the semiconductor wafer 10 to be laser processed by the imaging means 23 and control means (not shown) is executed. do. In other words, the imaging means 23 and the control means (not shown) include a preliminary division line 101 formed in a predetermined direction of the semiconductor wafer 10 and a laser beam that irradiates a laser beam along the preliminary division line 101. Image processing such as pattern matching for positioning the light collector 224 of the irradiation means 22 is performed, and alignment of the laser beam irradiation position is performed. In addition, alignment of the laser beam irradiation position is similarly performed with respect to the division scheduled line 101 formed in the direction orthogonal to the predetermined direction formed in the semiconductor wafer 10. At this time, the surface 10a, on which the scheduled dividing line 101 of the semiconductor wafer 10 is formed, is located downwards, and the imaging means 13 is applied to the optical system and the infrared light to catch the infrared illuminating means and the infrared as described above. Since the imaging means including the imaging element (infrared ray (CCD)) or the like for outputting a corresponding electric signal is provided, the division scheduled line 101 can be imaged from the back surface 10b.

As described above, if the scheduled dividing line 101 formed on the semiconductor wafer 10 held on the chuck table 21 is detected and alignment of the laser beam irradiation position is made, as shown in Fig. 5A. Similarly, the chuck table 21 is moved to the laser beam irradiation area where the condenser 224 of the laser beam irradiation means 22 for irradiating the laser beam is located, and one end of the predetermined division scheduled line 101 (Fig. 5). The left end in (a)) is positioned directly below the condenser 224 of the laser beam irradiation means 12. Then, the chuck table 21, that is, the semiconductor wafer 10, is irradiated with a predetermined processing in the direction indicated by the arrow X1 in FIG. Move at speed. As shown in FIG. 5B, the irradiation position of the condenser 224 of the laser beam irradiation means 22 is located at the other end of the division line 101 (the right end in FIG. 5B). When it has reached, the irradiation of the pulsed laser beam is stopped and the movement of the chuck table 21, that is, the semiconductor wafer 10 is stopped. In this altered layer forming step, the light collecting point P of the pulsed laser beam is matched to the vicinity of the surface 10a (bottom surface) of the semiconductor wafer 10. As a result, the deteriorated layer 110 is formed from the surface 10a toward the inside while being exposed to the surface 10a (bottom surface) of the semiconductor wafer 10. This altered layer 110 is formed as a melt stocking layer.

The processing conditions in the altered layer forming step are set as follows, for example.

Light source: LD excitation Q switch Nd: YVO4 laser

Wavelength: 1064nm Pulsed Laser

Pulse output: 10μJ

Condensing spot diameter: φ1㎛

Repetition frequency: 100 kHz

Feedrate: 100mm / sec

The altered layer 110 may be formed only inside so as not to be exposed to the front surface 10a and the rear surface 10b, and the plurality of laser processing processes described above may be performed a plurality of times by changing the light collecting point P stepwise. The altered layer 110 may be formed.

If the deterioration layer 110 is formed along all the division lines 101 in the semiconductor wafer 10 by the deterioration layer forming process described above, the semiconductor wafer 10 is formed on an adhesive tape having a larger area than the semiconductor wafer 10. Execute the adhesive tape adhering process.

That is, as shown in FIG. 6, the back surface 10b of the semiconductor wafer 10 in which the deterioration layer 110 was formed along the dividing line 101 on the surface of the adhesive tape 3 is stuck. Therefore, the surface 10a of the semiconductor wafer 10 is upward. In the illustrated example, the adhesive tape 3 is coated with an acrylic resin-based adhesive layer on the surface of a sheet base material made of a resin having elasticity such as polyvinyl chloride (PVC) having a thickness of 70 µm. The adhesive tape 3 is formed in a rectangular shape and has an area larger than the area of the semiconductor wafer 10 and to which an annular frame, which will be described later, is attached.

On the other hand, the adhesive tape bonding step may be carried out before the deterioration layer forming step, in which case the deterioration layer forming step described above is carried out while the surface 10a of the semiconductor wafer 10 is attached to the surface of the adhesive tape 3. do.

Subsequently, the adhesive tape 3 to which the semiconductor wafer 10 is attached is extended to divide the semiconductor wafer 10 into individual chips along the division scheduled line 101 on which the deterioration layer 110 is formed, and between the chips. A tape expansion process is performed to form the gap.

In this tape expanding step, as shown in FIGS. 7A and 7B, the four peripheral portions of the adhesive tape 3 to which the semiconductor wafer 10 is adhered are respectively sandwiched by the holding members 4, 4, 4, 4. The clamping members 4, 4, 4 and 4 are pulled outward as shown by the arrows, respectively. As a result, since the adhesive tape 3 extends in four directions, the tensile force acts on the semiconductor wafer 10 attached to the adhesive tape 3 in the direction indicated by the arrow, and as shown in Fig. 7B. The semiconductor wafer 10 is broken along the scheduled dividing line 101 whose strength is degraded by the deterioration layer 110 and is divided into individual semiconductor chips 100. In this tape expansion process, since the adhesive tape 3 is expanded as mentioned above, the semiconductor wafer 10 is divided into individual semiconductor chips 100, and the space | interval S is formed between each chip. On the other hand, in the tape expansion process, according to the experiments of the inventors, etc., when the adhesive tape 3 is stretched by about 20 mm, the semiconductor wafer 10 is divided along the scheduled line 101 where the deteriorated layer 110 is formed. It could break. At this time, the space | interval S between each semiconductor chip 100 divided individually became about 1 mm.

If the tape expansion step was carried out, the chip is divided into individual chips 100 as shown in Figs. 8A and 8B in a state where the gap S is formed between the chips 100 as described above. A frame bonding step of attaching the ring-shaped frame 5 to the adhesive tape 3 so as to surround the semiconductor wafer 10 is performed. In this way, the adhesive tape 3 is attached to the adhesive tape 3 in a state in which the adhesive tape 3 is expanded to form a space S between the chips 100. The expanded state is maintained, and the interval S is maintained between each chip 100.

Subsequently, the tensile force acting on the holding member 4, 4, 4, 4 is released, and the adhesive tape 3 is cut along the outer circumference of the ring-shaped frame 5, so as to be individually shown in FIG. The semiconductor wafer 10 divided into the chips 100 is supported by the ring-shaped frame 5 through the adhesive tape 3. Therefore, the semiconductor chips 100 divided individually do not contact each other, and it can prevent that the semiconductor chips 100 contact each other at the time of conveyance etc., and to be damaged.

On the other hand, in order to easily pick up the semiconductor chip 100 from the adhesive tape 3, as the adhesive tape 3, it is preferable to use the UV tape in which the adhesive force of the adhesion layer fell by irradiating an ultraviolet-ray.

According to the wafer dividing method according to the present invention, by dividing the adhesive tape with the wafer to divide the wafer into individual chips along the dividing line where the deterioration layer is formed, the individual chips are formed in a state in which gaps are formed between the chips. Since the adhesive tape is attached to the annular frame so as to surround the wafer divided into chips, the spacing of the chips divided individually is maintained. Therefore, the chips are not in contact with each other, and damage due to the contact of the chips with each other during transportation can be prevented.

Claims (1)

A wafer in which a plurality of scheduled lines are formed in a lattice shape on the surface, and a wafer in which functional elements are formed in a plurality of areas partitioned along the plurality of scheduled lines, divided into individual chips along the scheduled lines. As the division method of A deterioration layer forming process of irradiating a laser beam having transparency to the wafer along the predetermined dividing line, and forming a deteriorated layer along the predetermined dividing line in the wafer; An adhesive tape adhesion step of attaching the wafer to the adhesive tape sandwiched by a holding member having a larger area than the wafer before or after the deterioration layer forming step; A tape expansion step of dividing the adhesive tape to which the wafer is attached and dividing the wafer into individual chips along the scheduled division line on which the deterioration layer is formed, and forming a gap between the chips; And a frame bonding step of attaching a ring-shaped frame to the adhesive tape so as to surround the wafer divided into individual chips after the adhesive tape is expanded after the tape expanding process. .

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