Tuning pore size with ALD
This is a follow-up to my initial report on using the ALD to coat pnc-Si pores with Al2O3. Below are the TEM micrographs and histogram of a series of depositions I performed with 3 different process times. I was targeting a 5 nm, 10 nm, and 20 nm reduction in pore diameter.
The average diameter is 19.1, 13.7, 10.5 and 7.6 nm for the untreated, 5, 10, and 20 nm deposition, respectively. The porosity is 10.3%, 4.9%, 3.2% and 0.2% for the untreated, 5, 10, and 20 nm deposition, respectively.
There is still some anisotropy in the deposition, which I will try to address by tweaking some process parameters (e.g. precursor dwell and purge time).