Wafer processing method

A wafer processing method of processing a wafer, the wafer including, on a top surface, a device region having a device formed in each of a plurality of regions demarcated by a plurality of planned dividing lines formed in a lattice manner and a peripheral surplus region surrounding the device region, and the wafer having a circular recessed portion on an undersurface side corresponding to the device region and including a ring-shaped reinforcing portion along an outer circumference of the circular recessed portion, the wafer processing method comprising:

• a first fixing step of making a first resin sheet conform to the circular recessed portion and the ring-shaped reinforcing portion by fixing an undersurface of the wafer to the first resin sheet;
• after the first fixing step, a second fixing step of forming a cavity between the first resin sheet fixed to the circular recessed portion and a second resin sheet by fixing the second resin sheet to the first resin sheet fixed to the ring-shaped reinforcing portion;
• after the second fixing step, a holding step of holding the second resin sheet of the wafer by a chuck table;
• and
• a groove forming step of forming a separating groove for separating the circular recessed portion and the ring-shaped reinforcing portion from each other.