Carrier assemblies, planarizing apparatuses including carrier assemblies, and methods for planarizing micro-device workpieces

A carrier assembly for holding a micro-device workpiece during mechanical or chemical-mechanical polishing, the carrier assembly comprising:

• a head having a chamber;
• a magnetic field source carried by the head, the magnetic field source including a plurality of elements for inducing magnetic fields in the chamber;
• a flexible member in the chamber at least partially defining an enclosed cavity;
• and
• a fluid with magnetic elements in the cavity, wherein the individual magnetic fields move the fluid and/or the magnetic elements such that a corresponding section of the cavity expands and exerts pressure against a portion of the micro-device workpiece.

A carrier assembly for retaining a micro-device workpiece during mechanical or chemical-mechanical polishing, the carrier assembly comprising:

• a head having a chamber;
• a plurality of magnets for inducing magnetic fields in the chamber;
• a nonmagnetic float within the chamber;
• and
• a magnetic fluid including magnetic elements within the chamber, wherein the individual magnetic fields cause the magnetic fluid and/or the magnetic elements to move within the chamber and drive the nonmagnetic float toward the micro-device workpiece such that the float exerts a force against at least a portion of the workpiece.