Wafer processing method including a filament forming step and an etching step

Patent metadata

Field	Value
Publication number	US-9349646-B2
Application number	US-201414185189-A
Country	US
Kind code	B2
Filing date	Feb 20, 2014
Priority date	Mar 1, 2013
Publication date	May 24, 2016
Grant date	May 24, 2016

Abstract

A wafer processing method for dividing a wafer along a plurality of division lines to obtain a plurality of individual chips. The wafer processing method includes a filament forming step of applying a pulsed laser beam having a transmission wavelength to the wafer along each division line in the condition where the focal point of the pulsed laser beam is set inside the wafer in a subject area to be divided, thereby forming a plurality of amorphous filaments inside the wafer along each division line, and an etching step of etching the amorphous filaments formed inside the wafer along each division line by using an etching agent to thereby divide the wafer into the individual chips along the division lines.

First claim

What is claimed is:

1. A wafer processing method for dividing a wafer along a plurality of division lines to obtain a plurality of individual chips, wherein said wafer includes an upper surface and a lower surface, said wafer processing method comprising:
a filament forming step of applying a pulsed laser beam having a transmission wavelength to said wafer along each division line in a condition where the focal point of said pulsed laser beam is set inside said wafer in a subject area to be divided, thereby forming a plurality of amorphous filaments inside said wafer along each division line, wherein said amorphous filaments are each composed of a hole and an amorphous layer formed around said hole, wherein the filament forming step is performed under processing conditions configured to result in the holes of said amorphous filaments being separated from each other at predetermined intervals; and
an etching step of etching said amorphous filaments formed inside said wafer along each division line by using an etching agent to thereby divide said wafer into said individual chips along said division lines,
wherein said pulsed laser beam to be applied in said filament forming step is focused by a focusing lens, and the numerical aperture of said focusing lens is set in the range of 0.1 to 0.3, and
wherein each of the holes of the amorphous filaments and the amorphous layer extend from the upper surface of the wafer to the lower surface of the wafer, thereby extending completely through the wafer.

2. The wafer processing method according to claim 1 , wherein the pulsed laser beam used during said filament forming step has a wavelength of 1030 nm and a focused spot diameter of 10 μm.

3. The wafer processing method according to claim 1 , wherein the pulsed laser beam used during said filament forming step has a repetition frequency of 50 kHz and a pulse width of 10 ps.

4. The wafer processing method according to claim 1 , wherein the pulsed laser beam used during said filament forming step is focused upon an intermediate position between the upper and lower surfaces of the wafer, whereby the pulsed laser beam is defocused on the lower surface of the wafer.

5. The wafer processing method according to claim 1 , wherein a work feed speed of relative movement between said wafer and a laser beam applying means for applying said pulsed laser beam is 800 mm/s.

6. The wafer processing method according to claim 1 , wherein each of the predetermined intervals is 16 μm.

7. The wafer processing method according to claim 1 , wherein the amorphous layers of adjacent ones of the amorphous filaments are connected with each other.

8. The wafer processing method according to claim 1 , wherein each of the holes is completely surrounded by the amorphous layer associated therewith.

Assignees

• Disco Corp

Inventors

• Morikazu Hiroshi
• Takeda Noboru

Classifications

• H10P54/00 Primary

  Cutting or separating of wafers, substrates or parts of devices · CPC title

• B23K26/0648

  comprising lenses · CPC title

• B23K26/00

  Working by laser beam, e.g. welding, cutting or boring · CPC title

• B23K26/53

  for modifying or reforming the material inside the workpiece, e.g. for producing break initiation cracks · CPC title

• H01L21/78 Primary

  Electricity · mapped topic