Wafer treating method
A wafer treating method includes the steps of irradiating a wafer, provided with devices on the face side, from the back side with a laser beam capable of being transmitted through the wafer, while converging the laser beam to a predetermined depth, so as to form a denatured layer between the face side and the back side of the wafer, and separating the wafer into a back-side wafer on the back side relative to the denatured layer and a face-side wafer on the face side relative to the denatured layer. The denatured layer remaining in the face-side wafer is removed, and the face-side wafer is finished to a predetermined thickness, whereby the devices constituting the face-side wafer are finished into products, and the back-side wafer is recycled.
1. A method of treating a wafer provided with a plurality of devices on the face side, said method comprising:
providing a plurality of said devices on the face side of said wafer;
adhering a protective tape to the face side of said wafer;
positioning said wafer upon a chuck table, face side down, such that the back side of the wafer is exposed;
a denatured layer forming step of irradiating said wafer from the back side with a laser beam having such a wavelength as to permit transmission of said laser beam through said wafer, while adjusting a converging point of said laser beam to a predetermined depth from said back side, so as to form a denatured layer between the face side and the back side of said wafer;
a separating step of separating said wafer into a back-side wafer on the back side relative to said denatured layer and a face-side wafer on the face side relative to said denatured layer; and
a finishing step of removing said denatured layer remaining in said face-side wafer so as to finish said face-side wafer to a predetermined thickness;
wherein said separating step results in said face-side wafer having a plurality of the devices formed on the face side thereof, and said back-side wafer with no devices formed thereon, and
wherein said back-side wafer is recycled.
2. The method of treating the wafer according to claim 1 , further comprising a step of grinding said face-side wafer, wherein said grinding step is performed after said separating step.
3. The method of treating the wafer according to claim 1 , wherein said denatured layer forming step is performed while rotating said wafer and simultaneously irradiating a laser beam on said wafer by linearly moving a laser beam irradiation means.
4. The method of treating the wafer according to claim 1 , wherein said devices are ICs.
5. The method of treating the wafer according to claim 1 , wherein said devices are LSIs.