Grinding method

A grinding method of grinding a reverse side of a disk-shaped workpiece having on a face side thereof a device region where a plurality of devices are formed and an outer circumferential surplus region surrounding the device region, with a grinding stone part of a grinding wheel having an annular wheel base, the grinding stone part being disposed in an annular pattern on a surface of the wheel base, comprising:

• a face side protecting step of covering the face side of the workpiece with a protective member;
• a holding step of holding the face side of the workpiece under suction on a disk-shaped chuck table that is rotatable about a central axis of a first rotational shaft;
• after the holding step, an oblique grinding step of rotating the grinding wheel about the central axis of a second rotational shaft, the grinding wheel being mounted on a lower end of the second rotational shaft, having a diameter smaller than the diameter of the chuck table, and disposed above the chuck table, tilting the second rotational shaft with respect to the first rotational shaft such that a bottom of a first portion of the grinding wheel that is positioned above an outer circumferential portion of the chuck table is higher than the bottom of a second portion of the grinding wheel that is positioned above a central portion of the chuck table, and then moving the grinding wheel and the chuck table relatively to each other to bring the grinding wheel and the chuck table closer to each other along a direction parallel to the first rotational shaft, thereby forming a disk-shaped recess in the reverse side of the workpiece by grinding a central portion of the reverse side of the workpiece that corresponds to the device region thicknesswise across the workpiece, the disk-shaped recess being defined by a circular ground portion and a ring-shaped stiffening portion surrounding the circular ground portion and left unground;
• and
• after the oblique grinding step, a tilt changing and grinding step of grinding the reverse side of the workpiece while gradually changing a tilt of the second rotational shaft to orient the second rotational shaft parallel to the first rotational shaft.