Context: Silicon remains the central material in microelectronics. A major reason for this is its oxide, which passivates the surface, acts as a dielectric, and can be exploited in lithography. The Semiconductor Industry Roadmap shows that the demands on the dielectric in the next ten years cannot be met by known technologies, and alternatives either do not exist or cannot be implemented on the timescale required. The oxide demanded would be of order 1nm thick, uniform across a wafer, and reliable over 10 years under an electrical stress of about 1Volt.
Current activities: It is clear (partly from our work) that the processes of oxidation change dramatically when the oxide is less than a few nanometres thick. We have been looking carefully at both the growth processes themselves (state of the art electronic structure calculations; Monte-Carlo simulations) and the ways in which the oxide might break down (where we identify similarities to excitonic and defect processes known for bulk silicon dioxides). Our results show the importance of charged oxidising species. We see some possibility that the oxide might be improved.
Other people involved (including external collaborators)
Dr Tony Harker (UCL); Dr Vitor Torres (Aveiro, Portugal). Dr Ross Nobes and Dr Andrew Horsfield (Fujitsu European Centre for Information Technology). Dr Chioko Kaneta (Fujitsu Laboratories, Japan). Dr Art Edwards (USAF, Albuquerque). Dr Carl Sofield (AEA Technology)
Recent (or relevant) papers (this is an incomplete list)
337. Oxidation of Silicon: the VLSI
Gate Dielectric?
C J Sofield, A M Stoneham 1995, Semicon Sci & Eng. 10 215-240.
343. Early Stages of Silicon
Oxidation.
V J Torres, A M Stoneham C J Sofield, A H Harker, C F Clement 1995
Interface Science 3 131-144.
371. Modelling the oxide and the
oxidation process: Can silicon oxidation
be solved?
A M Stoneham (invited talk, St Petersburg NATO Advanced Research
Institute)
pps 79-88 of "Fundamental Aspects of
Ultrathin Dielectrics in Si-based
devices: towards an atomic scale understanding"
A M Stoneham and C J Sofield 1998(edited E Garfunkel, E Gusev and A
Vul'); Kluwer.
395 Silicon oxidation kinetics;
A M Stoneham to appear (in 2000?) in Encyclopaedia of Materials,
Science and Technology (Elsevier/Pergamon) in the volume Semiconductor
Processing and IC Fabrication.
### Dynamics of Silicon Oxidation
A. M. Stoneham, M. A. Szymanski and A. L. Shluger (text of invited
talk, to appear in Proceedings of the MRS Fall Meeting 1999)
208. Transport Processes in Silicon
Oxidation I : Dry Oxidation
J.P. Hagon, A.M. Stoneham and M. Jaros 1987 Phil. Mag. B55, 211-224
(also TP 1175).
209. Transport Processes in Silicon
Oxidation II : Wet Oxidation
J.P. Hagon, A.M. Stoneham and M. Jaros 1987 Phil. Mag. B55, 225-235
(also TP 1176)
210. Image Charges and their
Influence on the Growth and Nature of
Thin Oxide Films
A M Stoneham and P.W. Tasker. 1987 Phil. Mag. B55, 237-252 (also
TP 1167).
211. Oxidation and the Structure of
the Silicon/Oxide Interface
A M Stoneham, C.R.M. Grovenor and A. Cerezo 1987, Phil. Mag. B55,
201-210.
228. Effects of Stress on the Dry
Oxidation of Silicon: Theory of
Molecular Oxygen Diffusion in Silica
J.P. Hagon and A.M. Stoneham, 1987, Phil. Mag. Lett. 56, 41-45
(1987).
251. Oxidation of Silicon
N.F. Mott, S. Rigo, F. Rochet and A.M. Stoneham, 1989 Phil. Mag.
B60 189-212. (also REPRINTED in "Sir Nevill Mott: 65 Years in Physics"
1995 edited N F Mott and A S Alexandrov: Singapore: World Scientific.)
296. Oxidation of Silicon. Invited
Talk at INFOS meeting
A M Stoneham 1992 pps 19-32 of "Insulating Films on Semiconductors
1991" (edited W Eccleston and M Uren); Bristol: Adam Hilger. Also
AEA-InTec-0436
322. Environment of the Pb Centre at
the Si (111)/Oxide Interface.
C K Ong, A H Harker and A M Stoneham 1993 Interface Science 1 139-146