Selective Etching of Silicon Oxide versus Nitride with Low Oxide Etching Rate

Hsing Chen Wu; Sheng Hung Tu; Min Chieh Yang; Emanuel Cooper

doi:10.4028/www.scientific.net/SSP.255.75

Paper Titles

Towards Atomic-Layer-Scale Processing of High Mobility Channel Materials in Acidic Solutions for N5 and N7 Technology Nodes
p.51

Comparison of the Chemical Passivation of GaAs, In_0.53Ga_0.47As, and InSb with 1-Eicosanethiol
p.55

Digital Etching of GaAs Materials: Comparison of Oxidation Treatments
p.61

Thin Layer Etching of Silicon Nitride: Comparison of Downstream Plasma, Liquid HF and Gaseous HF Processes for Selective Removal after Light Ion Implantation
p.69

Selective Etching of Silicon Oxide versus Nitride with Low Oxide Etching Rate
p.75

Metrology for High Selective Silicon Nitride Etch
p.81

Study on the Etching Selectivity of Oxide Films in Dry Cleaning Process with NF₃ and H₂O
p.86

Titanium Nitride Hard Mask Removal with Selectivity to Tungsten in FEOL
p.91

Analysis of Si Wet Etching Effect on Wafer Edge
p.97

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Selective Etching of Silicon Oxide versus Nitride with Low Oxide Etching Rate

Abstract:

This paper describes both aqueous and solvent-based formulations aimed at etching silicon oxide (SiO_x) with etching rates (E/R) of the order of 10-20 A/min with selectivity greater than 5 with respect to silicon nitride (SiN_x) . Diluted hydrofluoric acid (dHF) with very low pH was tried first but the selectivity was found to increase only with higher SiO_x E/R. Solvent-based formulations derived from previous work also behaved in a similar way, however its SiO_x E/R could be reduced by modifying the total fluoride concentration inside formulation. Finally, we found that low SiO_x E/R could also be implemented in the diluted buffer-oxide etch (BOE) solution and the selectivity could be adjusted by addition of a specific surfactant at a very low concentration level.