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Chemical sputtering by H{sub 2}{sup +} and H{sub 3}{sup +} ions during silicon deposition

Journal Article · · Journal of Applied Physics
DOI:https://doi.org/10.1063/1.4960351· OSTI ID:22597688
;  [1];  [2];  [3]
  1. Debye Institute for Nanomaterials Science-Physics of Devices, Utrecht University, 5656 AE Eindhoven (Netherlands)
  2. FOM Institute DIFFER-Dutch Institute for Fundamental Energy Research, 5600 HH Eindhoven (Netherlands)
  3. Department of Applied Physics, Plasma and Materials Processing, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands)
We investigated chemical sputtering of silicon films by H{sub y}{sup +} ions (with y being 2 and 3) in an asymmetric VHF Plasma Enhanced Chemical Vapor Deposition (PECVD) discharge in detail. In experiments with discharges created with pure H{sub 2} inlet flows, we observed that more Si was etched from the powered than from the grounded electrode, and this resulted in a net deposition on the grounded electrode. With experimental input data from a power density series of discharges with pure H{sub 2} inlet flows, we were able to model this process with a chemical sputtering mechanism. The obtained chemical sputtering yields were (0.3–0.4) ± 0.1 Si atom per bombarding H{sub y}{sup +} ion at the grounded electrode and at the powered electrode the yield ranged from (0.4 to 0.65) ± 0.1. Subsequently, we investigated the role of chemical sputtering during PECVD deposition with a series of silane fractions S{sub F} (S{sub F}(%) = [SiH{sub 4}]/[H{sub 2}]*100) ranging from S{sub F} = 0% to 20%. We experimentally observed that the SiH{sub y}{sup +} flux is not proportional to S{sub F} but decreasing from S{sub F} = 3.4% to 20%. This counterintuitive SiH{sub y}{sup +} flux trend was partly explained by an increasing chemical sputtering rate with decreasing S{sub F} and partly by the reaction between H{sub 3}{sup +} and SiH{sub 4} that forms SiH{sub 3}{sup +}.
OSTI ID:
22597688
Journal Information:
Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 5 Vol. 120; ISSN JAPIAU; ISSN 0021-8979
Country of Publication:
United States
Language:
English