Abstract: A retaining ring can be shaped by machining or lapping the bottom surface of the ring to form a shaped profile in the bottom surface. The bottom surface of the retaining ring can include flat, sloped and curved portions. The lapping can be performed using a machine that dedicated for use in lapping the bottom surface of retaining rings. During the lapping the ring can be permitted to rotate freely about an axis of the ring. The bottom surface of the retaining ring can have curved or flat portions.

Abstract: A platen for chemical mechanical polishing of a substrate includes a surface upon which a polishing pad can be placed, a support structure, and a controller. The surface has a first region and a second region and is operable to exert force against the polishing pad during polishing. The support structure is located beneath the second region and is operable to cause the second region to exert more force than the first region. The controller is operable to adjust the amount of force that is exerted by the second region.

Abstract: A magnetic photocatalyst composite particle includes a magnetic composition and at least one photocatalyst particle secured to the magnetic composition. The magnetic photocatalyst composite particles can be nano-sized. The magnetic photocatalyst composite particles permit high levels of photocatalytic chemical activity to be combined with controllable particle movement and allow the formation of improved reactors for the treatment of water and air.