Influence of the height difference between the first and second nitride layer on erosion and dishing in the dual nitride approach for shallow trench isolation
Heylen, N Grillaert, J Vrancken, E Badenes, G Rooyackers, R Meuris, M Heyns, Marc #
Electrochemical Society Inc
Chemical Mechanical Planarization in Integrated Circuit Device Manufacturing vol:98 issue:7 pages:26-36
Electrochemical Society Series
2nd International Symposium on Chemical Mechanical Planarization in Integrated Circuit Device Manufacturing at the 193rd Annual Meeting of the Electrochemical Society location:San Diego, CA, USA date:5-7 May 1998
The optimization of Shallow Trench Isolation (STI) formed with a dual nitride (DN) approach and chemical mechanical polish (CMP) process is described. During STI processing the planarity after the CMP step is determined by the within-die nitride thickness range between features of varying size and pattern density. The ultimate goal for the CMP step is to remove all the oxide on top of the active areas without overpolishing especially the small, isolated ones. For the dual nitride concept the within-die nitride thickness range is reduced significantly by optimizing the thickness of the trench filling oxide and in this way also the height difference between the active area protecting nitride layer. and the second nitride layer. on the oxide in the trenches. Putting the top of the second nitride layer higher,then the top of the first one results in good planarity across all features.