Dear all,
Merry X'mas.
I have troubles with Boron diffusion. I do a thermal diffusion with
Borofilm 100 from *EMULSITONE COMPANY*
(http://www.emulsitone.com/bf100.html). The Si wafer is N-type (100)
(1~20ohm cm) with 60nm thermal oxide on the top. I spin on Borofilm 100
(3000rpm for 30seconds) and use the oxide layer as a mask. I anneal
samples at 1000 degree C for 2 hours and 4 hours under the ambient 97%
N2 + 3% O2, which is recommended by the Emulsitone Company. But after I
etched the oxidation with HF (10%), I found the resistance is about
10ohm/sq everywhere. It seems the Boron penetrated the 60nm oxidation
layer. But from calculation, (see
http://www.batnet.com/enigmatics/semiconductor_processing/selected_shorts/Moistu
re_barriers.html),
the penetration should only be a few nanometers.
I hope someone can give me some advices on boron diffusion:
1) Anneal temperature and time
I need an average contration ~10^18 /cm^3 with a depth
about 0.5~1um
2) Mask choice: thickness and type
if it's thermal oxide, what's the thickness?
if I use LPCVD to deposite SiO2, what's the thickness?
Thanks a lot. Any advices will be appreciated!
Best
Hongtao