Discussion Overview
The discussion centers on the diffusion of helium through silicon, particularly in the context of ion implantation and potential applications such as pre-amorphization or gettering transition metals. Participants explore the factors influencing diffusion rates, including temperature, implantation depth, and the presence of nanocavities.
Discussion Character
- Exploratory
- Technical explanation
- Debate/contested
- Mathematical reasoning
Main Points Raised
- One participant inquires about the diffusion rate of helium in silicon and the possibility of using lookup tables or formulas for this purpose.
- Another participant suggests that the inquiry may relate to pre-amorphization or gettering metals, providing specific parameters such as a 30 keV beam and a typical anneal profile of 900°C for 1 hour.
- It is noted that the minimum anneal temperature is 700°C, and that nanocavities created during the process may not be stable above 1200°C.
- Participants discuss the weak dependence of anneal time on ion density, emphasizing the stronger influence of implantation depth and anneal temperature.
- One participant proposes a hypothetical scenario involving a silicon sphere at 20°C with a single helium atom at the center, seeking to determine the diffusion time under these conditions.
- Another participant expresses skepticism about helium diffusion at 20°C, suggesting that thermal movement may be insufficient without applied stress, and questions whether the silicon is polycrystalline or amorphous.
- Concerns are raised about the potential creation of nanocavities at a 40 keV energy level, with a participant humorously acknowledging the uncertainty of their formation.
- A rough estimate is provided, indicating that diffusion time at 20°C could be significantly longer than at higher temperatures, with a suggestion that it may take around 55 hours.
- One participant recommends consulting the Defect and Diffusion Forum for historical data on diffusion in silicon.
Areas of Agreement / Disagreement
Participants express varying views on the conditions affecting helium diffusion, with no consensus reached on specific diffusion rates or the applicability of lookup tables. The discussion remains unresolved regarding the exact mechanisms and parameters influencing diffusion.
Contextual Notes
Limitations include the dependence on temperature and implantation depth, as well as the potential impact of nanocavities, which are not fully resolved in the discussion.
