Etch selectivity of a wet chemical formulation for premetal cleaning

Jeremy W. Epton; Deborah L. Jarrett; Ian J. Doohan

doi:10.1117/12.425245

20 April 2001 Etch selectivity of a wet chemical formulation for premetal cleaning

Jeremy W. Epton, Deborah L. Jarrett, Ian J. Doohan

Proceedings Volume 4405, Process and Equipment Control in Microelectronic Manufacturing II; (2001) https://doi.org/10.1117/12.425245
Event: Microelectronic and MEMS Technologies, 2001, Edinburgh, United Kingdom

Abstract

This paper examines the relative etching rates of doped and thermal silicon dioxide when using NSSL etchant, comprising of a mixture of ammonium fluoride, water and ammonium dihydrogen phosphate [(NH₄)H₂PO₄] and investigates their dependence on both temperature and mixture composition. The possible reaction mechanism is discussed and compared with the known mechanism for standard buffered oxide etchants (BOE). The observed etch selectivity and mechanisms of BOE and NSSL are also compared with the behavior of a third chemical formulation, referred to as mixed oxide etchant, which comprises of ammonium fluoride (NH₄F) solution, diammonium hydrogen phosphate [(NH₄)₂HPO₄] and orthophosphoric acid (H₃PO₄). It is concluded that no major change in oxide selectivity is observed if either BOE or NSSL etchants are used in the metal pre-clean process.

Citation Download Citation

Jeremy W. Epton, Deborah L. Jarrett, and Ian J. Doohan "Etch selectivity of a wet chemical formulation for premetal cleaning", Proc. SPIE 4405, Process and Equipment Control in Microelectronic Manufacturing II, (20 April 2001); https://doi.org/10.1117/12.425245

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