Wafer processing method using a ring frame and a polyester sheet

A wafer processing method for dividing a wafer along a plurality of division lines to obtain a plurality of individual device chips, the division lines being formed on a front side of the wafer to thereby define a plurality of separate regions where a plurality of devices are individually formed, the wafer processing method comprising:

• a ring frame preparing step of preparing a ring frame having an inside opening for accommodating the wafer;
• a polyester sheet providing step of positioning the wafer in the inside opening of the ring frame and providing a polyester sheet having no adhesive layer on a back side of the wafer and on a back side of the ring frame;
• a uniting step of heating the polyester sheet while applying a pressure to the polyester sheet after performing the polyester sheet providing step, thereby uniting the wafer and the ring frame through the polyester sheet by thermocompression bonding to form a frame unit in a condition where the front side of the wafer and a front side of the ring frame are exposed;
• a dividing step of applying a laser beam to the wafer along each division line, the laser beam having an absorption wavelength to the wafer, after performing the uniting step, thereby forming a division groove in the wafer along each division line to divide the wafer into the individual device chips;
• and
• a pickup step of blowing air to each device chip through the polyester sheet to push up each device chip, thereby picking up each device chip from the polyester sheet after performing the dividing step;
• wherein the polyester sheet is formed of polyethylene terephthalate, and the polyester sheet is heated in the range of 250° C. to 270° C. in the uniting step.

A wafer processing method for dividing a wafer along a plurality of division lines to obtain a plurality of individual device chips, the division lines being formed on a front side of the wafer to thereby define a plurality of separate regions where a plurality of devices are individually formed, the wafer processing method comprising:

• a ring frame preparing step of preparing a ring frame having an inside opening for accommodating the wafer;
• a polyester sheet providing step of positioning the wafer in the inside opening of the ring frame and providing a polyester sheet having no adhesive layer on a back side of the wafer and on a back side of the ring frame;
• a uniting step of heating the polyester sheet while applying a pressure to the polyester sheet after performing the polyester sheet providing step, thereby uniting the wafer and the ring frame through the polyester sheet by thermocompression bonding to form a frame unit in a condition where the front side of the wafer and a front side of the ring frame are exposed;
• a dividing step of applying a laser beam to the wafer along each division line, the laser beam having an absorption wavelength to the wafer, after performing the uniting step, thereby forming a division groove in the wafer along each division line to divide the wafer into the individual device chips;
• and
• a pickup step of blowing air to each device chip through the polyester sheet to push up each device chip, thereby picking up each device chip from the polyester sheet after performing the dividing step;
• wherein the polyester sheet is formed of polyethylene naphthalate, and the polyester sheet is heated in the range of 160° C. to 180° C. in the uniting step.