Wafer processing method

摘要

A method of processing a wafer having a device area where a plurality of devices are formed and a peripheral marginal area surrounding the device area on the front side of the wafer is disclosed. The devices are formed in regions defined by division lines. Each device has a plurality of bump electrodes on the front side. A first laser beam is applied through dicing tape from the back side along the boundary between the device area and the peripheral marginal area, with the focal point of the first laser beam set inside the wafer, thereby forming an annular modified layer inside the wafer. A second laser beam is applied through the dicing tape from the back side along each division line with the focal point of the second laser beam set inside the wafer, thereby forming a modified layer inside the wafer along each division line.

主权项

1. A wafer processing method of processing a wafer having a device area where a plurality of devices are formed and a peripheral marginal area surrounding said device area on a front side of said wafer, said devices being respectively formed in a plurality of separate regions defined by a plurality of division lines, each device having a plurality of bump electrodes on the front side, said wafer processing method comprising:
a wafer supporting step of attaching a front side of a dicing tape to the back side of said wafer and supporting said dicing tape at its peripheral portion to an annular frame; a wafer holding step of holding the front side of said wafer on an upper surface of a chuck table as a holding surface in a condition where a back side of said dicing tape is oriented upward and fixing said annular frame by means of clamps; an annular modified layer forming step of applying a first laser beam having a transmission wavelength to said dicing tape and said wafer through said dicing tape from the back side thereof along a boundary between said device area and said peripheral marginal area in a condition where the focal point of said first laser beam is set inside said wafer, thereby forming an annular modified layer inside said wafer along the boundary between said device area and said peripheral marginal area; and a modified layer forming step of applying a second laser beam having a transmission wavelength to said dicing tape and said wafer through said dicing tape from the back side thereof along each division line in a condition where the focal point of said second laser beam is set inside said wafer after performing said annular modified layer forming step, thereby forming a modified layer inside said wafer along each division line.