Controlled etch-back for better STI – CMP performance of SOG-filled structures
Original Publication Date: 2005-Jan-25
Included in the Prior Art Database: 2005-Jan-25
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In wafer production technologies, the usual High-Density-Plasma-CVD-Oxide (CVD: Chemical Vapor Deposition) will not be able to fill without voids the shallow-trenches of the future sub 70nm-nodes. As an alternative, Spin-on materials (e.g. Spin On Glass SOG-process) may be employed for shallow trench isolation (STI-structures) for nodes below 70nm ground rule. To have uniform filling in trenches, an overfill is necessary. The usual process after filling in the trenches is a CMP process (Chemical Mechanical Polishing) which removes the excess overfill. Longer polish time is employed or the use of a hybrid approach like an unselective polish with fast removal rates is done prior to a selective CMP process to SiN (Silicon Nitride), like fixed abrasive polishing. The greater the time of polishing, the higher is the risk of having non-uniformities.