ion implantation question

John Shott shott at stanford.edu
Mon Nov 21 18:59:35 PST 2011


Stephanie:

What are the dose and energy of the implant that you plan to do?

To first order, the implant depth in oxide is comparable to that in silicon.  As I recall (don't take this as an accurate number) the mean implant depth of 100 keV phosphorus is about 125 nm. However, if you tried to use 125 nm of masking oxide, you'd be in serious trouble because fully half of the dopant would penetrate the oxide. Absent more accurate numbers, I'd suggest that a masking oxide thickness of 2.5 to 3.0 times the mean implant depth in silicon. For 100 keV phosphorus, I'd suggest that about 400 nm of oxide is probably safe. Note: heat treatment following implant also needs to be considered but is often a second order consideration unless post-implant heat treatment is really hot or long. 

Let me know if you have other questions or are worried about trusting my now-addled memory about such matters. 

John

Sent from my iPhone

On Nov 21, 2011, at 5:04 PM, Stephanie Claussen <sclaussen at stanford.edu> wrote:

> Hi all,
> 
> I am planning on doing phosphorous ion implantation this week at INNOViON in San Jose. This will be on an already-fabricated vertical pin structure. I was planning to deposit LPCVD oxide over my entire structure, then pattern and etch it to open up the n regions where I want the ions implanted.
> 
> Can anyone tell me how thick this oxide should be to prevent P doping in my p region? Your prompt responses are greatly appreciated, as this is a process I was planning on carrying out over the next day or two.
> 
> Thanks so much,
> Stephanie



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