AVS 47th International Symposium
    Manufacturing Science and Technology Thursday Sessions
       Session MS-ThM

Paper MS-ThM3
Fast-Ramp Annealing for Reducing Implant-Induced Transient Enhanced Diffusion

Thursday, October 5, 2000, 9:00 am, Room 304

Session: Advanced Modeling and Control for IC Manufacturing
Presenter: M.Y.L. Jung, University of Illinois, Urbana-Champaign
Authors: M.Y.L. Jung, University of Illinois, Urbana-Champaign
R. Gunawan, University of Illinois, Urbana-Champaign
R.D. Braatz, University of Illinois, Urbana-Champaign
E.G. Seebauer, University of Illinois, Urbana-Champaign
Correspondent: Click to Email
Some experimental evidence has accumulated in recent years to support the use of "spike anneal" temperature trajectories with very fast heating and cooling rates for making ultrashallow junctions by ion implantation. Improved device properties have been claimed using heating rates of 400 C/s or more. This procedure supposedly optimizes junction depth and sheet resistance by reducing transient-enhanced diffusion (TED) of the dopant. However, the theoretical justification for using such fast ramps has been weak. Since the design and use of fast-ramp annealing tools will require substantial investments by equipment manufacturers and IC manufacturers alike, it is important to confirm by TCAD modeling the existence and potential magnitude of such effects. TED has long been modeled using a large set of reaction-diffusion equations for the dopant, point defects, and extended defects. However, current commercial and public-domain SUPREM-based software mishandles or ignores several important aspects of the reaction-diffusion network. We briefly discuss how we have fixed these problems, focusing in particular how proper incorporation of surface oxidation or nitridation kinetics closely couples the gas ambient in the annealer to dopant motion down near the junction within the Si bulk. We then show how variations in heating and cooling rates can be used to favor or disfavor important reaction-diffusion pathways within the overall system of effects that governs TED. In particular, we point out how the widely-used contant-temperature annealing step near 500 C for pyrometer calibration actually influences subsequent profile evolution in a profound way.