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Poly-Si/TiN/HfO2 gate stack etching in high-density plasmas.
- Source :
- Journal of Vacuum Science & Technology: Part B-Microelectronics & Nanometer Structures; May/Jun2007, Vol. 25 Issue 3, p767-778, 12p, 11 Black and White Photographs, 1 Diagram, 2 Charts, 4 Graphs
- Publication Year :
- 2007
-
Abstract
- The authors have investigated the dry etch mechanisms of complex poly-Si/TiN/HfO<subscript>2</subscript> gate stacks and the issues that are correlated with the introduction of a thin metal layer in the gate stack. Based on atomic force microscopy (AFM) and scanning electron microscope measurements, they will first show that a mixture of HBr and Cl<subscript>2</subscript> at low rf bias power is required to successfully pattern the TiN layer without damaging the HfO<subscript>2</subscript> gate oxide. Second, it is demonstrated that the introduction of a metal layer in the gate stack prevents charging effects during the last etching steps of the silicon part of the gate. Transmission electron microscope measurements and x-ray photoelectron spectroscopy analyses of the gate sidewalls show that the thickness of the silicon sidewall passivation layer decreases during the O<subscript>2</subscript> free metal etching step potentially inducing silicon gate profile distortion such as notch. However, the notch can be eliminated by etching the Si/TiN gate in a single step process instead of stopping at the TiN surface. Finally, AFM measurements show that during the TiN etching step, a low rf bias power is required to prevent damage (punching through) of the HfO<subscript>2</subscript> layer. However, even under these conditions, a significant silicon recess (oxidation of the c-Si beneath the HfO<subscript>2</subscript> layer) is observed even if TiN is etched in an O<subscript>2</subscript>-free chemistry. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 10711023
- Volume :
- 25
- Issue :
- 3
- Database :
- Complementary Index
- Journal :
- Journal of Vacuum Science & Technology: Part B-Microelectronics & Nanometer Structures
- Publication Type :
- Academic Journal
- Accession number :
- 25365944
- Full Text :
- https://doi.org/10.1116/1.2732736