JP2014036134A - Device processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device processing method capable of forming an ID on a rear surface of a device without deteriorating transverse intensity of a device.SOLUTION: While CVD gas is supplied from a rear surface of a device D, laser beam 7 is radiated, so as to form rear surface ID information of the device D by optical CVD. Cracks are not generated inside the device D, and therefore, transverse intensity of the device is not deteriorated.

Description

  The present invention relates to a device processing method for forming product information on the back surface of a device.

  A wafer formed by dividing a plurality of devices such as an IC and an LSI on a surface by dividing lines is divided into individual devices by a dicing apparatus and used for an electric device such as a mobile phone and a personal computer. Individual device is engraved with individual identification number information (ID information) such as function, product number, and lot number.

  If the individual identification number information (ID information) is imprinted after the wafer is divided into individual devices, the product productivity will be reduced. Therefore, before dividing the wafer into individual devices, laser beams are emitted from the back of each device. A technique for irradiating and imprinting ID information has been proposed (see, for example, Patent Document 1 below).

JP 2008-178886 A

  However, when ID information is imprinted by irradiating a laser beam on the back surface of the device, there is a problem that fine cracks are formed inside the device and the bending strength of the device is lowered.

  The present invention has been made in view of the above circumstances, and has a problem to be solved by enabling the formation of ID information on the back surface of a device without reducing the bending strength of the device. ing.

  The present invention relates to a device processing method in which individual identification information of each device is formed on the back surface of a wafer formed on the surface of a semiconductor substrate by dividing a plurality of devices by a predetermined division line. Thus, individual identification information is formed on the back surface of the device.

When the semiconductor substrate is a silicon substrate, the CVD gas is preferably Cr (CO) ₆ .

  In the present invention, since individual identification information is formed on the back surface of the device by optical CVD from the back surface of the device, the individual identification information can be formed on the back surface of the wafer without generating fine cracks inside the device. Therefore, it can prevent that the bending strength of a device falls.

It is a perspective view which shows the structure of a processing apparatus. It is a perspective view which shows the structure of a wafer. It is sectional drawing which shows the state which supplies the gas for CVD to the back surface of a wafer, and irradiates a laser beam. It is a perspective view which shows the state which forms ID information on the back surface of a wafer.

  A processing apparatus 1 shown in FIG. 1 is a processing apparatus that performs optical CVD (Chemical Vapor Deposition) from the back side of a semiconductor substrate. First, the configuration of the processing apparatus 1 will be described. The processing apparatus 1 includes an apparatus base 2, and an upright base 3 extending in the Z-axis direction is erected on the upper surface of the apparatus base 2 on the rear side in the Y-axis direction. On the upper surface side of the apparatus base 2, a holding table 4 that rotatably holds the wafer, an X-axis direction feeding unit 20 that moves the holding table 4 in the X-axis direction, and a Y that moves the holding table 4 in the Y-axis direction. Axial feed means 30.

  The X-axis direction feeding means 20 includes a ball screw 21 extending in the X-axis direction, a motor 22 connected to one end of the ball screw 21, a bearing portion 23 that rotatably supports the ball screw 21 at the other end of the ball screw 21, A pair of guide rails 24 disposed in parallel with the ball screw 21 and a moving base 25 slidably disposed on the guide rail 24 are provided. A nut structure is formed at the lower part of the moving base 25 and is screwed into the ball screw 21. On the moving base 25, Y-axis direction feeding means 30 is disposed. When the motor 22 rotates the ball screw 21, the moving base 25 is guided by the guide rail 24 and moves in the X-axis direction, and accordingly, the Y-axis direction disposed on the moving base 25. The feeding means 30 and the holding table 4 can be processed and fed in the X-axis direction.

  The Y-axis direction feed means 30 includes a ball screw 31 extending in the Y-axis direction, a motor 32 connected to one end of the ball screw 31, a bearing portion 33 that rotatably supports the ball screw 31 at the other end of the ball screw 31, A pair of guide rails 34 disposed in parallel with the ball screw 31 and a moving base 35 slidably disposed on the guide rail 34 are provided. A nut structure is formed at the lower central portion of the moving base 35 and is screwed into the ball screw 31. When the motor 32 rotates the ball screw 31, the moving base 35 is guided by the guide rail 34 and moves in the Y-axis direction. Accordingly, the holding table 4 disposed on the moving base 35. Can be moved in the Y-axis direction to adjust the position of the holding table 4 in the Y-axis direction.

  The holding table 4 is connected to a cylindrical base 6 and is rotatable, and a cover table 5 is disposed around the holding table 4. The upper surface of the holding table 4 is a holding surface 4a for sucking and holding the wafer.

  An infrared camera 8 is provided at one end of the upright base 3. The infrared camera 8 can detect a processing region by optical CVD by imaging the wafer held on the holding table 4 with infrared rays.

  In the vicinity of the infrared camera 8, for example, a processing means 10 that performs photo-CVD on the wafer W shown in FIG. 2 is disposed. As shown in FIG. 1, the processing means 10 includes a head 100 that irradiates a laser beam downward, a laser oscillator 11 that oscillates the laser beam, an output adjustment unit 12 that adjusts the output of the laser beam, and an irradiation position of the laser beam. And control means 13 for controlling.

  The control means 13 shown in FIG. 3 includes at least a memory and a CPU for storing the coordinate information 14 of the semiconductor substrate and the ID information 15 constituting the individual identification information of the product. A Y-axis galvano mirror 16 is disposed in the irradiation direction of the laser beam output from the output adjusting means 12, and an X-axis galvano mirror 17 is disposed in the vicinity of the Y-axis galvano mirror 16. The control unit 13 can control the laser beam whose output is adjusted by the output adjustment unit 12 to be deflected in the Y-axis direction by a predetermined angle when it is projected onto the Y-axis galvanometer mirror 16. Further, the control means 13 can control the laser beam deflected and reflected by the Y-axis galvanometer mirror 16 to be deflected in a predetermined angle X-axis direction when projected to the X-axis galvanometer mirror 17.

  As shown in FIG. 3, a mirror 18 that reflects a laser beam oscillated from the laser oscillator 11 and deflected by the Y-axis galvanometer mirror 16 and the X-axis galvanometer mirror 17 is attached inside the head 100. Further, a telecentric lens 19 is disposed below the mirror 18. By using the telecentric lens 19, when the laser beam reflected downward by the mirror 18 penetrates the telecentric lens 19, the laser beam can be passed in parallel with the optical axis of the telecentric lens 19.

  As shown in FIG. 3, a reaction chamber 101 is formed below the telecentric lens 19. A gas supply port 42 for supplying CVD gas to the reaction chamber 101 is formed at the side of the reaction chamber 101. The gas supply port 42 is connected to the CVD gas supply unit 40 via the valve 41. Further, a gas exhaust port 43 is formed inside the head 100 for exhausting the unnecessary CVD gas released from the lower portion of the head 100 toward the exhaust unit 44 outside the processing means 10.

  Below, the processing method which forms ID information with optical CVD with respect to the back surface Wb of the wafer W shown in FIG. 2 using the processing apparatus 1 comprised as mentioned above is demonstrated.

  The wafer W shown in FIG. 2 is configured by forming a plurality of devices D partitioned by a lattice-shaped scheduled division line S on the surface Wa of a semiconductor substrate. The device D is not formed on the back surface Wb which is the opposite surface of the front surface Wa, and photo CVD is performed on the back surface Wb by the processing means 10 shown in FIG. A semiconductor substrate to be processed is formed of, for example, a silicon substrate.

  The holding surface 4a of the holding table 4 shown in FIG. 1 sucks and holds the front surface Wa side of the wafer W shown in FIG. 2, and the back surface Wb of the wafer W is exposed upward. Thereafter, the X-axis direction feeding means 20 shown in FIG. 1 moves the holding table 4 in the X-axis direction together with the Y-axis direction feeding means 30 to position the wafer W directly below the infrared camera 8. The infrared camera 8 irradiates infrared rays from the back surface Wb side of the wafer W, detects an area where ID information is formed by optical CVD, and sends the detected information to the control means 13. The region for forming the ID information is the back side of the position of the device D formed on the front surface Wa of the wafer W on the back surface Wb of the wafer W.

  Next, the holding table 4 is further processed and fed in the X-axis direction by the X-axis direction feeding means 20 to position the holding table 4 immediately below the processing means 10.

When processing the wafer W, for example, the following processing conditions are set in the processing means 10.
[Processing conditions]
Laser beam wavelength: 349 nm (Nd: YLF laser third harmonic)
Average power: 100mW
Repetition frequency: 4 kHz
Pulse width: 30 ns
Spot diameter: 20 μm

As shown in FIG. 3, after the holding table 4 is positioned immediately below the processing means 10, the CVD gas supply unit 40 sends the CVD gas into the reaction chamber 101, and the laser oscillator 11 oscillates the pulsed laser beam 7. The laser beam is irradiated toward the back surface Wb of the wafer W. When the semiconductor substrate is a silicon substrate, for example, carbonyl “Cr (CO) ₆ ” can be used as the CVD gas. The control means 13 stores in advance the coordinate information 14 of the wafer W and the ID information 15 formed on the device D.

  The laser beam 7 is reflected by the Y-axis galvanometer mirror 16 and the X-axis galvanometer mirror 17, reflected by the mirror 18, passes through the telecentric lens 19 positioned below, and enters the reaction chamber 101 in parallel with the optical axis of the telecentric lens 19. enter.

  When the laser beam 7 is irradiated to the reaction chamber 101 into which the CVD gas is introduced, a Cr layer is deposited on the back side of the device by optical CVD. That is, the portion irradiated with the laser beam 7 is heated, the CVD gas is thermally decomposed, and the Cr layer is deposited on the heated portion. At this time, the ID information 9 is formed on the back surface of the device by controlling the irradiation position of the laser beam corresponding to the ID of each device for each device. The Cr layer desirably has a thickness of approximately 100 nm. In order to effectively perform photo-CVD on the back surface Wb of the wafer W, it is desirable that the distance H1 between the head 100 and the back surface Wb of the wafer W is set to 0.5 mm to 1 mm, for example.

  Further, the unnecessary CVD gas discharged downward from the reaction chamber 101 shown in FIG. 3 flows into the gas exhaust port 43 and is exhausted to the exhaust unit 44.

  When the ID information 9 shown in FIG. 4 is formed on the back surface of the device D for one row shown in FIG. 2 while feeding the holding table 4 in the X-axis direction, the Y-axis direction feeding means 30 shown in FIG. Similarly, while moving in the axial direction, the back surface Wb of the adjacent device D is irradiated with the laser beam 7 to form ID information 9 by optical CVD. As a result, ID information 9 is formed on the back side of all the devices D shown in FIG. Thus, after ID information is formed in each device D, the wafer W is divided into the individual devices D by dicing or laser.

  As described above, in the processing means 10, it is possible to form ID information on the back surface Wb of the wafer W by light CVD by irradiating the laser beam 7 while supplying the CVD gas to the back surface of the device D. . Therefore, ID information can be formed on the back surface Wb of the wafer W without generating fine cracks inside the device D. Therefore, it can prevent that the bending strength of the device D falls.

1: Processing device 2: Device base 3: Standing base 4: Holding table 4a: Holding surface 5: Supporting portion 6: Cylindrical portion 7: Laser beam 8: Infrared camera 9: ID information 10: Processing means 100: Head 101: Reaction chamber 11: Laser oscillator 12: Output adjusting means 13: Control means 14: Coordinate information 15: ID information 16: Y-axis galvano mirror 17: X-axis galvano mirror 18: Mirror 19: Telecentric lens 20: X-axis direction sending means 21 : Ball screw 22: Motor 23: Bearing part 24: Guide rail 25: Moving base 30: Y-axis direction feeding means 31: Ball screw 32: Motor 33: Bearing part 34: Guide rail 35: Moving base 40: CVD gas supply part 41: Valve 42: Gas supply port 43: Gas exhaust port 44: Exhaust part W: Wafer Wa: Front surface Wb: Back surface D: Device S: Minute Scheduled line

Claims (2)

A device processing method for forming individual identification information of each device on a back surface of a wafer formed on the surface of a semiconductor substrate by dividing a plurality of devices by a division line,
A device processing method for forming individual identification information on a back surface of a device by optical CVD from the back surface of the device. The device processing method according to claim 1, wherein the semiconductor substrate is a silicon substrate, and the gas for CVD is Cr (CO) ₆ .

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