Kelvin-Probe Force Microscopy Defect Study of Ion Implanted Thermal Oxide Thin Films on Silicon

• Published in: Conference on Optoelectronic and Microelectronic Materials and Devices, 2004 pp. 405 - 408
• Main Authors: Lay, M.D.H., Pakes, C.I., McCallum, J.C.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 2004
• Subjects: Area measurement; Atomic force microscopy; Chemicals; Lead compounds; Rapid thermal annealing; Resists; Semiconductor thin films; Silicon; Thermal force; Topology
• ISBN: 0780388208; 9780780388208
• DOI: 10.1109/COMMAD.2004.1577575

We have studied changes to the surface potential of thermally grown oxides on silicon implanted with 15 keV P or Si using Kelvin-probe force microscopy (KFM). Oxides of 15 nm thickness were implanted through photoresist masks to create disk like islands of 3 μm diameter in the underlying silicon substrate with fluences up to 1×10 14 cm -2 . Atomic force microscopy shows no change to the topology of the sample except for the case of samples implanted at high fluence (1×10 14 P/cm 2 ) and flux (4.7×10 10 cm -2 s -1 ), which lead to observable depressions in the oxide. Results from KFM measurements show that there is a change in the surface potential of implanted areas for all samples however. Phosphorus implanted samples show a larger change in potential compared with preliminary results from silicon implanted samples. This increased change may be due to a flux dependence on defect generation but chemical effects associated with phosphorus or the effect of ionised phosphorus cannot be ruled out. Results from samples that have the implanted P activated by rapid thermally annealing at 1000°C for 5 seconds show the surface potential of implanted areas to be reduced but not eliminated. The residual difference may be due to the change in the substrate workfunction due to activated P donors. The measured change in surface potential has also been found to depend on the imaging height