Laminate processing method

A laminate processing method of dividing a laminate into individual image sensor chips, the laminate in which a glass substrate is disposed through a transparent adhesive layer on a front surface of a wafer where a plurality of image sensors are formed in a plurality of respective regions demarcated by a plurality of crossing division lines, the method comprising:

• a cut groove forming step of positioning a cutting blade from a side of the glass substrate constituting the laminate and cutting a region of the glass substrate corresponding to each of the division lines, thereby forming a cut groove reaching the adhesive layer in the glass substrate;
• a division start point forming step of positioning a focal point of a laser beam having a transmission wavelength to the wafer inside a region of the wafer corresponding to each of the division lines from a back surface of the wafer, applying the laser beam thereto, continuously forming a modified layer inside the wafer, and forming a crack reaching from the modified layer to the adhesive layer, thereby forming a division start point;
• a laminate supporting step of supporting the glass substrate side of the laminate through an expandable tape to an annular frame having an inside opening with a size large enough to accommodate the laminate therein, at least after the cut groove forming step is carried out;
• a dividing step of, after the division start point forming step and the laminate supporting step are carried out, expanding the expandable tape to form a division groove along the division start point, and dividing the laminate into individual image sensor chips along the division groove;
• a water-soluble resin filling step of filling a water-soluble resin in the division groove formed in the dividing step;
• a modified layer removing step of positioning a cutting blade in the division groove formed in the back surface of the wafer to cut the division groove in a state in which the water-soluble resin is solidified or half-solidified, thereby removing the modified layer;
• and
• a water-soluble resin removing step of supplying cleaning water from the back surface of the wafer with a state in which the expandable tape is expanded being maintained, thereby removing the water-soluble resin being filled in the cut groove and the division groove.