Platen with diaphragm and method for optimizing wafer polishing

A platen for use in a chemical mechanical planarization (CMP) system, comprising:

• a structure configured with at least two apertures, one or more of the at least two apertures defining at least one localized fluid-pressure platen zone, one or more of the at least two apertures defining at least one fluid-bearing platen zone configured to allow a flow of fluid-bearing fluid, the fluid-bearing fluid having a tendency to freely-flow from the at least one fluid-bearing platen zone out of the platen;
• and
• a membrane covering the one or more of the at least two apertures that define each of the at least one localized fluid-pressure platen zones, the membrane being configured so that in response to fluid of the respective at least one localized fluid-pressure platen zone, the membrane is extendable into the fluid-bearing fluid of the at least one fluid-bearing platen zone, the membrane being configured with a first section secured to the structure around the one or more of the at least two apertures, the membrane being configured with a second section surrounded by the first section, and
• the extendable configuration of the membrane comprises the second section having a flexible characteristic for movement relative to the respective one or more of the at least two apertures in response to the fluid of the respective at least one localized fluid-pressure platen zone, the movement of the second section extends the second section into the flow of the fluid-bearing fluid.

A platen for use in a chemical mechanical planarization (CMP) system in which a polishing pad is configurable to apply selected polishing pressures to different areas of a wafer to be planarized, the platen comprising:

• a fluid-bearing structure configured with a first plurality of apertures for transferring polishing pressure control fluid, the apertures being configured to define a plurality of localized fluid-pressure platen zones for applying selectable polishing pressure control pressures to the polishing pad;
• and
• a membrane corresponding to each localized fluid-pressure platen zone, each membrane covering respective ones of the apertures corresponding to a respective one of the localized fluid-pressure platen zones, each membrane being sealed to the fluid-bearing structure around the respective ones of the apertures to separate the polishing pressure control fluid of the respective localized fluid-pressure zone from the fluid-bearing structure, the sealing of each membrane enabling different selectable localized fluid pressures to be applied to each localized fluid-pressure platen zone to provide differential polishing pressure control pressures to the polishing pad;
• the fluid-bearing structure being further configured with a second plurality of apertures for supplying fluid-bearing fluid between the respective membranes and the polishing pad.

A method of limiting consumption of fluid by a platen of a chemical mechanical planarization system, comprising the operations of:

• providing the platen with a first aperture communicating with a self-contained localized fluid-pressure platen zone;
• providing the platen with a second aperture for defining at least one fluid-bearing platen zone;
• admitting fluid-bearing fluid into the second aperture, the fluid-bearing fluid tending to flow from the second aperture and out of the platen;
• and
• admitting fluid-pressure fluid into the first aperture so that the self-contained localized fluid-pressure platen zone separates the fluid-pressure fluid of the localized fluid-pressure zone from the fluid-bearing platen zone.

A method, of limiting consumption of fluid by a platen of a chemical mechanical planarization system, comprising the operations of:

• providing the platen with a first aperture communicating with a self-contained localized fluid-pressure platen zone;
• providing the platen with a second aperture for defining at least one fluid-bearing platen zone, wherein the platen is a fluid-bearing platen and defines a fluid-bearing gap between a polishing pad and the fluid-bearing platen, the fluid-bearing gap extending outwardly from a central platen zone to the self-contained localized fluid-pressure zone;
• configuring the fluid-bearing platen with at least one self-contained localized fluid-pressure zone outwardly of the central platen zone and having a flexible membrane;
• and
• admitting fluid-bearing fluid into the second aperture, the fluid-bearing fluid tending to flow from the second aperture and out of the platen;
• and
• admitting fluid-pressure fluid into the first aperture so that the localized fluid-pressure platen zone limits the flow of the fluid-bearing fluid out of the platen, wherein the admitting fluid-pressure fluid operation is controlled to cause the membrane to control a localized fluid-pressure applied to the polishing pad and a resulting localized planarization pressure applied via the polishing pad to a workpiece, wherein the membrane enters the gap to restrict the flow of the fluid-bearing fluid through the fluid-bearing gap and out of the platen.