| AVS 54th International Symposium | |
| Thin Film | Monday Sessions |
| Session TF-MoM |
| Session: | Atomic Layer Deposition and Applications |
| Presenter: | L. Henn-Lecordier, University of Maryland |
| Authors: | L. Henn-Lecordier, University of Maryland E. Robertson, University of Maryland P. Banerjee, University of Maryland G.W. Rubloff, University of Maryland |
| Correspondent: | Click to Email |
While atomic layer deposition (ALD) shows unique promise for highly controlled deposition of super-conformal thin films, its perfection and practice are limited by (1) reactant dose (inter)dependencies that reflect deviations from perfect self-limiting reaction and (2) the numerous permutations of stoichiometry that must be investigated to exploit ternary and higher materials systems. We have developed a combinatorial ALD approach to efficiently address these challenges. A wafer-scale (4- OD) substrate-heated ALD mini-reactor delivers reactant gases across the wafer, maintained in a small reactor volume to achieve short cycle times. Downstream mass spectrometry reveals the ALD surface chemistry in real time, enabling direct observation of reaction product generation as a function of dose, as well as direct thickness vs. time determinations during nucleation and growth stages of the ALD process.1,2 With increasing dose, nominally complete surface saturation conditions are observed. As reactant dose is decreased, incomplete surface coverage is expected and identified, which corresponds to across-wafer depletion conditions in the cross-flow geometry of the mini-reactor. By achieving such depletion, various combinations of reactant dose ratios for binary constituents provide a combinatorial gradient library for ALD process recipe optimization. Results for Al2O3 deposited by ALD from TMA and H2O demonstrate the ability to create linear thickness gradients across the wafer. This combinatorial synthesis is coupled with post-process electrical characterization of MIS capacitors using I-V and C-V measurements automated to assess several hundred devices across the wafer, complemented by wafer maps of thickness and composition. Together these directions reflect an effective strategy for evaluating and optimizing ALD process recipes as well as extending the approach to ternary systems, e.g. Hf aluminates. Work supported in part by MKS Instruments.
1"Real-time observation and optimization of tungsten ALD process cycle", W. Lei, L. Henn-Lecordier, M. Anderle, Gary W. Rubloff, M. Barozzi, and M. Bersani, J. Vac. Sci. Technol.B 24 (2), 780-789 (Mar/Apr 2006).
2"Real-time sensing and metrology for atomic layer deposition processes and manufacturing", L. Henn-Lecordier, W. Lei, M. Anderle, and G.W. Rubloff, J. Vac. Sci. Technol. B 25 (1), 130-139 (Jan/Feb 2007).