JP2009059749A - Wafer cutting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wafer cutting method preventing contamination from adhering on the surface of a device while preventing corrosion of bonding pads formed on the device. <P>SOLUTION: The wafer cutting method for cutting a wafer held on a chuck table while supplying cutting water with a rotating cutting blade includes cutting the wafer while supplying hydrogen water as the cutting water to the rotating cutting blade and a cut portion of the wafer cut by the cutting blade. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a wafer cutting method for cutting a wafer such as a semiconductor wafer.

  In the semiconductor device manufacturing process, a plurality of regions are partitioned by dividing lines called streets arranged in a lattice pattern on the surface of a substantially wafer-shaped semiconductor wafer, and devices such as ICs, LSIs, etc. are partitioned in the partitioned regions. Form. Then, the semiconductor wafer is cut along the streets to divide the region in which the device is formed to manufacture individual semiconductor chips. In addition, optical device wafers with gallium nitride compound semiconductors laminated on the surface of a sapphire substrate are also divided into individual optical devices such as light emitting diodes and laser diodes by cutting along the streets, and are widely used in electrical equipment. ing.

  Cutting along the streets of the above-described semiconductor wafer, optical device wafer or the like is usually performed by a cutting device called a dicer. This cutting apparatus includes a chuck table for holding a wafer such as a semiconductor wafer, a cutting means having a cutting blade for cutting the wafer held by the chuck table, and a cutting water supply for supplying cutting water to the cutting blade. The cutting blade is cooled by supplying the cutting water to the rotating cutting blade by the cutting water supply means, and the cutting operation is performed while supplying the cutting water to the cutting portion of the wafer by the cutting blade.

As the cutting water supplied to the cutting part of the wafer by the cutting blade described above, pure water is used in order to prevent deterioration of the quality of the device. Pure water has a high specific resistance value (resistivity) and conductivity. Since it is low, static electricity is generated due to friction and the wafer is easily charged. Contamination adheres to the bonding pad formed on the device due to electrostatic charging, and the quality of the device is remarkably deteriorated. In order to solve such a problem, the following patent document discloses a method for preventing electrostatic charge on a wafer by mixing carbon dioxide into pure water to give cutting water appropriate conductivity. .
JP 2001-30170 A

  Thus, when carbon dioxide is mixed into pure water, it becomes acidic, and there is a problem that the bonding pad made of metal formed on the device is corroded. In particular, the bonding pad formed of aluminum is severely corroded.

  The present invention has been made in view of the above-mentioned facts, and a main technical problem thereof is a wafer cutting method capable of preventing contamination from adhering to the surface of a device without corroding a bonding pad formed on the device. Is to provide.

In order to solve the above main technical problem, according to the present invention, a wafer cutting method of cutting while supplying cutting water with a cutting blade that rotates a wafer held on a chuck table,
Cutting the wafer while supplying hydrogen water as cutting water to the rotating cutting blade and the cutting portion of the wafer by the cutting blade;
A method for cutting a wafer is provided.

  It is desirable that ultrasonic vibration is applied to the hydrogen water.

  In the wafer cutting method according to the present invention, hydrogen water having high reducibility is supplied as cutting water to the cutting blade and the cutting portion of the wafer by the cutting blade, so that the surface of the wafer is reduced and contamination is prevented. . Further, in the wafer cutting method according to the present invention, hydrogen water having high reducibility is used as the cutting water, so that the bonding pad provided on the device formed on the wafer is not corroded.

  Preferred embodiments of a wafer cutting method according to the present invention will be described below in more detail with reference to the accompanying drawings.

  FIG. 1 is a perspective view of a cutting apparatus for carrying out the wafer cutting method according to the present invention. A cutting device 1 shown in FIG. 1 includes a device housing 2 having a substantially rectangular parallelepiped shape. In the apparatus housing 2, a chuck table 3 for holding a workpiece is disposed so as to be movable in a direction indicated by an arrow X that is a cutting feed direction. The chuck table 3 includes a suction chuck support 31 and a suction chuck 32 disposed on the suction chuck support 31. A workpiece is illustrated on a holding surface which is the upper surface of the suction chuck 32. Suction holding is performed by operating a suction means that does not. The chuck table 3 is configured to be rotatable by a rotation mechanism (not shown). The chuck table 31 is provided with a clamp 33 for fixing an annular frame that supports a wafer, which will be described later, as a workpiece through a dicing tape. The chuck table 3 configured as described above can be moved in a cutting feed direction indicated by an arrow X by a cutting feed means (not shown).

  A cutting apparatus 1 shown in FIG. 1 includes a spindle unit 4 as cutting means. The spindle unit 4 is moved in an index feed direction indicated by an arrow Y in FIG. 1 by an index feed means (not shown), and is moved in a cut feed direction indicated by an arrow Z in FIG. 1 by a notch feed means (not shown). ing. The spindle unit 4 is mounted on a moving base (not shown) and is adjusted to move in a direction indicated by an arrow Y that is an indexing direction and a direction indicated by an arrow Z that is a cutting direction, and the spindle housing 41 is freely rotatable. And a cutting blade 43 attached to the front end of the rotating spindle 42. For example, as shown in FIG. 2, the cutting blade 43 has a disk-shaped base 431 formed of aluminum, and diamond abrasive grains are hardened by nickel plating on the outer peripheral side surface of the base 431 to a thickness of 15 to 30 μm. The grinding wheel portion 432 is formed.

  Continuing with reference to FIG. 2, a blade cover 44 covering the upper half of the cutting blade 43 is attached to the front end of the spindle housing 41. The blade cover 44 includes a first cover member 441 mounted on the spindle housing 41 and a second cover member 442 mounted on the first cover member 441 in the illustrated embodiment. A female screw hole 441a and two positioning pins 441b are provided in the side surface of the first cover member 441, and an insertion hole 442a is provided in a position corresponding to the female screw hole 441a in the second cover member 442. It has been. Further, on the surface of the second cover member 442 facing the first cover member 441, two recesses (not shown) into which the two positioning pins 441b are fitted are formed. The first cover member 441 and the second cover member 442 configured in this way are provided with two recesses (not shown) formed in the second cover member 442 provided in the first cover member 441. The positioning is performed by fitting to the positioning pin 441b. Then, the fastening bolt 443 is inserted into the insertion hole 442a of the second cover member 442, and is screwed into the female screw hole 441a provided in the first cover member 441, whereby the second cover member 442 is engaged with the first cover member 442. The cover member 441 is attached.

  Cutting water supply pipes 451 and 452 are disposed on the first cover member 441 and the second cover member 442 constituting the blade cover 44, respectively. The upper ends of the cutting water supply pipes 451 and 452 are connected to the cutting water supply means 5. The cutting water supply means 5 in the illustrated embodiment includes a hydrogen water supply source 51, a hydrogen water supply pipe 52 that connects the hydrogen water supply source 51 and the cutting water supply pipes 451 and 452, and the hydrogen water supply pipe. And an electromagnetic opening / closing valve 53 disposed in the position 52. In the cutting water supply means 5 configured as described above, the communication between the hydrogen water supply source 51 and the cutting water supply pipes 451 and 452 is blocked when the electromagnetic on-off valve 53 is deenergized (OFF) and closed. When the electromagnetic on-off valve 53 is energized (ON) and opened, the hydrogen water supply source 51 and the cutting water supply pipes 451 and 452 are communicated with each other via the hydrogen water supply pipe 52. The hydrogen water stored in the hydrogen water supply source 51 is mixed with 1 to 2 ppm of hydrogen gas in pure water.

At the lower ends of the cutting water supply pipes 451 and 452, there are cutting water supply nozzles 461 and 462 that are respectively disposed on both sides of the grindstone portion 432 of the cutting blade 43 and inject cutting water toward both side surfaces of the grindstone portion 432. It is connected. The ultrasonic vibration applying means 47 is attached to the tips of the cutting water supply nozzles 461 and 462 (in FIG. 2, only the ultrasonic vibration applying means 47 attached to one of the cutting water supply nozzles 462 is provided. It is shown). This ultrasonic vibration applying means 47 is composed of an ultrasonic vibrator made of, for example, lead zirconate titanate (PB (Zi, Ti) O ₃ ), and is connected to a voltage applying means for applying an AC voltage (not shown). Yes.

  Returning to FIG. 1, the description will be continued. The cutting device 1 images the surface of the workpiece held on the chuck table 3 and detects an area to be cut by the cutting blade 43. It has. The imaging means 6 is composed of optical means such as a microscope and a CCD camera. Further, the cutting apparatus 1 includes a display unit 7 that displays an image captured by the imaging unit 6.

  In the cassette mounting area 8a of the apparatus housing 2, a cassette mounting table 8 for mounting a cassette for storing a workpiece is disposed. The cassette mounting table 8 is configured to be movable in the vertical direction by a lifting means (not shown). On the cassette mounting table 8, a cassette 9 for storing a semiconductor wafer 10 as a workpiece is placed. The semiconductor wafer 10 accommodated in the cassette 9 has a grid-like street formed on the surface thereof, and devices such as IC and LSI are formed in a plurality of rectangular areas partitioned by the grid-like street. The semiconductor wafer 10 thus formed is accommodated in the cassette 9 with the back surface adhered to the front surface of the dicing tape 12 mounted on the annular support frame 11.

  Further, the cutting apparatus in the illustrated embodiment is a semiconductor wafer 10 accommodated in a cassette 9 placed on a cassette placement table 8 (a state in which the wafer is supported on an annular frame 11 via a dicing tape 12). Is carried out on the temporary table 13, the first conveying means 15 for conveying the semiconductor wafer 10 carried on the temporary table 13 onto the chuck table 3, and cutting on the chuck table 3. A cleaning means 16 for cleaning the semiconductor wafer 10 is provided, and a second transport means 17 for transporting the semiconductor wafer 10 cut on the chuck table 3 to the cleaning means 16 is provided.

Next, a description will be given of a cutting operation line for cutting the semiconductor wafer 10 along a predetermined street using the above-described cutting apparatus 1.
A semiconductor wafer 10 (supported by an annular frame 11 via a dicing tape 12) accommodated in a predetermined position of a cassette 9 placed on the cassette placing table 8 is placed in a cassette by an elevator means (not shown). The mounting table 8 is moved to the carry-out position by moving up and down. Next, the carry-out / carry-in means 14 moves forward and backward to carry the semiconductor wafer 10 positioned at the carry-out position onto the temporary placement table 13. The semiconductor wafer 10 transported to the temporary placement table 13 is transported onto the chuck table 3 by the turning motion of the first transport means 15.

  When the semiconductor wafer 10 is placed on the chuck table 3, suction means (not shown) is operated to suck and hold the semiconductor wafer 10 on the chuck table 3. The annular frame 11 that supports the semiconductor wafer 10 via the dicing tape 12 is fixed by the clamp 33. In this way, the chuck table 3 holding the semiconductor wafer 10 is moved to a position directly below the imaging means 6. When the chuck table 3 is positioned immediately below the image pickup means 6, the street formed on the semiconductor wafer 10 is detected by the image pickup means 6, and the spindle unit 4 is moved and adjusted in the arrow Y direction as an indexing direction to cut the street and the cutting. A precision alignment operation with the blade 43 is performed.

  Thereafter, the chuck table 3 is moved to a cutting region below the cutting blade 43, and the cutting blade 43 is rotated in the direction indicated by the arrow 43a as shown in FIG. Then, the cutting blade 43 is positioned at a position where the lowermost end of the cutting blade 43 reaches the dicing tape 12. Then, the chuck table 3 holding the semiconductor wafer 10 by suction is moved at a predetermined cutting feed speed in a direction indicated by an arrow X1 which is a cutting feed direction. As a result, the semiconductor wafer 10 held on the chuck table 3 is cut along a predetermined street by the cutting blade 43 (cutting process). When performing this cutting process, the electromagnetic on-off valve 53 of the cutting water supply means 5 is energized (ON). Accordingly, the electromagnetic on-off valve 61 is opened as described above, and the hydrogen water supply source 51 and the cutting water supply pipes 451 and 452 are communicated with each other via the hydrogen water supply pipe 52. The grindstone of the cutting blade 43 through the hydrogen water supply pipe 52, the cutting water supply pipes 451 and 452, and the cutting water supply nozzles 461 and 462 (only one of the cutting water supply nozzles 462 is shown in FIG. 2). Injected toward the side surface of the portion 432. Thus, the supply amount of the hydrogen water sprayed toward the side surface of the grindstone 432 of the cutting blade 43 may be about 2 liters per minute (2 liters / minute). In the cutting process, an AC voltage is applied to the ultrasonic vibration applying means 47 mounted on the cutting water supply nozzles 461 and 462 by operating a voltage applying means (not shown). As a result, ultrasonic vibration is applied to the hydrogen water ejected from the cutting water supply nozzles 461 and 462. The ultrasonic frequency applied by the ultrasonic vibration applying unit 47 is preferably 1 to 3 MHz.

In the cutting process described above, highly reducing hydrogen water as the cutting water is sprayed from the cutting water supply nozzles 461 and 462 toward the side surface of the grindstone portion 432 of the cutting blade 43 and supplied to the cutting portion of the semiconductor wafer 10. The surface of the semiconductor wafer 10 is reduced and contamination is prevented from being attached. Further, since the ultrasonic vibration is applied to the hydrogen water sprayed from the cutting water supply nozzles 461 and 462 by the ultrasonic vibration applying means 47, the effect of preventing the adhesion of contamination is further improved. In addition, since hydrogen water with high reducibility is used as cutting water, the bonding pad provided in the device formed in the semiconductor wafer 10 is not corroded.
According to an experiment by the present inventor, when hydrogen water having a hydrogen concentration of 1.2 ppm was supplied at a rate of 2 liters / minute, a slight amount of contamination was found on the bonding pad provided in the device, but cutting was performed. Contamination adherence was about 1/10 compared with the case where pure water was used as water. In addition, when 1.5 MHz ultrasonic vibration was applied to the hydrogen water sprayed from the cutting water supply nozzles 461 and 462, no contamination was found on the bonding pads or the like provided in the device.

  When the semiconductor wafer 10 is cut along a predetermined street as described above, the chuck table 3 is indexed and fed in the direction indicated by the arrow Y in FIG. 1 to perform the above cutting process. When the cutting process is performed along all the streets extending in the predetermined direction of the semiconductor wafer 10, the chuck table 3 is rotated 90 degrees to extend in a direction orthogonal to the predetermined direction of the semiconductor wafer 10. By performing the cutting process along the streets, all the streets formed in a lattice shape on the semiconductor wafer 10 are cut and divided into individual devices. Each divided device does not fall apart due to the action of the dicing tape 12, and the state of the wafer supported by the annular frame 11 is maintained.

  As described above, when the cutting process is completed along the street of the semiconductor wafer 10, the chuck table 3 holding the semiconductor wafer 10 is first returned to the position where the semiconductor wafer 10 is sucked and held. Then, the suction holding of the semiconductor wafer 10 is released. Next, the semiconductor wafer 10 is transferred to the cleaning unit 16 by the second transfer unit 17. The semiconductor wafer 10 conveyed to the cleaning means 16 is cleaned here. The semiconductor wafer 10 thus cleaned is transported to the temporary table 13 by the first transport means 15 after drying. Then, the semiconductor wafer 10 is stored in a predetermined position of the cassette 9 by the unloading / loading means 14.

The perspective view of the cutting device for enforcing the cutting method of the wafer by the present invention to the present invention. The block block diagram of the cutting water supply means with which the cutting apparatus shown in FIG. 1 is equipped. Explanatory drawing of the cutting process implemented by the cutting device shown in FIG.

Explanation of symbols

1: Cutting device 2: Device housing 3: Chuck table 4: Spindle unit 43: Cutting blade 44: Blade cover 461, 462: Cutting water supply nozzle 5: Cutting water supply means 51: Hydrogen water supply source 52: Hydrogen water supply pipe 53: Electromagnetic on-off valve 6: Imaging means 7: Display means 9: Cassette 10: Semiconductor wafer 11: Annular support frame 12: Dicing tape 13: Temporary table 14: Unloading / loading means 15: First conveying means 16: Cleaning means 17: second conveying means

Claims (2)

A wafer cutting method of cutting while supplying cutting water with a cutting blade that rotates a wafer held on a chuck table,
Cutting the wafer while supplying hydrogen water as cutting water to the rotating cutting blade and the cutting portion of the wafer by the cutting blade;
A wafer cutting method characterized by the above.   The wafer cutting method according to claim 1, wherein ultrasonic vibration is applied to the hydrogen water.

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