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Controlled etch-back for better STI – CMP performance of SOG-filled structures

IP.com Disclosure Number: IPCOM000033749D
Original Publication Date: 2005-Jan-25
Included in the Prior Art Database: 2005-Jan-25
Document File: 1 page(s) / 43K

Publishing Venue

Siemens

Related People

Juergen Carstens: CONTACT

Abstract

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.

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Controlled etch-back for better STI - CMP performance of SOG-filled structures

Idea: Dr. Arabinda Das, DE-Dresden; Dr. Irene Bartusseck, DE-Dresden; Dr. Mark Hollatz, DE-

Dresden; Dr. Andreas Klipp, DE-Dresden

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.

Applying regular and/or hybrid CMP processes on filled trenches with a high overfill has several drawbacks, as they are time consuming and expensive and have a high risk of non-uniformities over the wafer. In order to overcome these problems, a controlled wet etch-back process has been developed (cf. Fig. 1) to reduce overfill to approximately 100nm and then proceed directly or selective polishing like e.g. a fixed...