Control of platen shape in chemical mechanical polishing

A method of locally polishing a substrate, comprising:

• supporting a polishing pad with a rotatable platen, the platen comprising at least one annular flexure extending from a central region of the platen and an actuator supported by the platen configured to adjust a vertical height of an edge of the annular flexure relative to the central region along an entire circumference of the annular flexure;
• positioning the substrate so that a portion of the substrate is over the annular flexure;
• moving the annular region of the substrate over the annular section;
• and
• generating relative motion between a polishing pad and a substrate so as to polish an overlying layer on the substrate.

A chemical mechanical polishing apparatus, comprising:

• a platen to support a polishing pad, the platen having a central section with an upper surface and an annular flexure surrounding or surrounded by the central section and having a top surface with a first edge adjacent to and coplanar with the upper surface and a second edge farther from the central section, wherein the annular flexure is tapered to be thinner toward the second edge;
• an actuator arranged to bend the annular flexure so as to modify a vertical position of the second edge of the annular flexure relative to the central section;
• a carrier head to hold a surface of a substrate against the polishing pad;
• and
• a motor to generate relative motion between the platen and the carrier head so as to polish an overlying layer on the substrate.

A chemical mechanical polishing apparatus, comprising:

• a platen to support a polishing pad, the platen having an upper portion and a lower portion, the upper portion having a central section with an upper surface;
• an annular flexure surrounding or surrounded by the central section and having a top surface with a first edge adjacent to and coplanar with the upper surface and a second edge farther from the central section;
• a pressurizable chamber between the upper platen and lower platen such that modifying pressurization of the chamber bends the annular flexure so as to modify a vertical position of the second edge of then annular flexure;
• a carrier head to hold a surface of a substrate against the polishing pad;
• and
• a motor to generate relative motion between the platen and the carrier head so as to polish an overlying layer on the substrate.