A wafer processing method includes forming a start point of division along division lines, providing, on a front surface of the wafer, a protective member for protecting the front surface of the wafer, grinding a back surface of the wafer to a desired thickness, forming division grooves in the division lines to divide the wafer into individual device chips, providing an expandable sheet to the back surface of the wafer and removing the protective member from the front surface of the wafer, coating the front surface of the wafer with an adhesive liquid having flowability, expanding and shrinking the sheet so as to allow the adhesive liquid to enter each of the division grooves and to discharge the adhesive liquid from the division grooves, and removing the adhesive liquid from the front surface of the wafer to clean a side surface of each of the division grooves.

A device wafer processing method includes a protective film coating step of coating a face side of a device wafer with a protective film, a laser processing step of applying a laser beam having a wavelength absorbable by the device wafer to the device wafer along streets and forming laser processing grooves that divide a device layer, a tape affixing step of affixing a tape to the protective film on the device wafer, a holding step of holding the face side of the device wafer by a holding table via the tape and exposing a reverse side of the device wafer, and a cutting step of cutting the device wafer held on the holding table, by a cutting blade from the reverse side along the streets, and dividing the device wafer into individual devices.

A die bonding method is disclosed, through coating bonding adhesive on front side of device wafer and bonding carrier wafer thereto, back-side connection structure can be formed on back side of device wafer to lead out an interconnect structure in device wafer to back side of device wafer, and dies thereon can be bonded at front sides to target wafer. Moreover, after device wafer is debonded from carrier wafer, the bonding adhesive is retained on front side of device wafer to provide protection to front side of device wafer during subsequent dicing of device wafer, and to avoid particles or etching by-products produced during dicing process from adhering to front side of device wafer. Such etching by-products are subsequently removed along with the bonding adhesive, ensuring cleanness of front sides of individual dies resulting from dicing process and improved quality of bonding of dies at front sides to target wafer.