Mechanisms and selectivity for etching of HfO{sub 2} and Si in BCl{sub 3} plasmas
- Department of Chemical and Biomolecular Engineering, University of Houston, 4800 Calhoun Road, Houston, Texas 77204 (United States)
The authors have investigated plasma etching of HfO{sub 2}, a high dielectric constant material, and poly-Si in BCl{sub 3} plasmas. Etching rates were measured as a function of substrate temperature (T{sub s}) at several source powers. Activation energies range from 0.2 to 1.0 kcal/mol for HfO{sub 2} and from 0.8 to 1.8 kcal/mol for Si, with little or no dependence on source power (20-200 W). These low activation energies suggest that product removal is limited by chemical sputtering of the chemisorbed Hf or Si-containing layer, with a higher T{sub s} only modestly increasing the chemical sputtering rate. The slightly lower activation energy for HfO{sub 2} results in a small improvement in selectivity over Si at low temperature. The surface layers formed on HfO{sub 2} and Si after etching in BCl{sub 3} plasmas were also investigated by vacuum-transfer x-ray photoelectron spectroscopy. A thin boron-containing layer was observed on partially etched HfO{sub 2} and on poly-Si after etching through HfO{sub 2} films. For HfO{sub 2}, a single B(1s) feature at 194 eV was ascribed to a heavily oxidized species with bonding similar to B{sub 2}O{sub 3}. B(1s) features were observed for poly-Si surfaces at 187.6 eV (B bound to Si), 189.8 eV, and 193 eV (both ascribed to BO{sub x}Cl{sub y}). In the presence of a deliberately added 0.5% air, the B-containing layer on HfO{sub 2} is largely unaffected, while that on Si converts to a thick layer with a single B(1s) peak at 194 eV and an approximate stoichiometry of B{sub 3}O{sub 4}Cl.
- OSTI ID:
- 21192378
- Journal Information:
- Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films, Journal Name: Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films Journal Issue: 4 Vol. 26; ISSN 1553-1813
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ACTIVATION ENERGY
BONDING
BORATES
BORON CHLORIDES
BORON OXIDES
DIELECTRIC MATERIALS
ETCHING
EV RANGE
HAFNIUM OXIDES
HYDROFLUORIC ACID
LAYERS
PERMITTIVITY
PLASMA
SILICON
SPUTTERING
SURFACE COATING
SURFACES
TEMPERATURE RANGE 0065-0273 K
THIN FILMS
X-RAY PHOTOELECTRON SPECTROSCOPY