[labnetwork] CVD Diborane Diffusion

[Bernard Alamariu]

Hi,

I think that you use this process to dope Si wafers, correct?
Or is it an in-situ doping of some Polysilicon film deposited by CVD, 
using Silane?

In any case you have a concurrent oxidation process with O2 flow at 1000C;
during which the Boron "segregates" into the SiO2 grown layer depleting the
Si substrate; so when you remove the oxide for 4 point probe the 
resistivity increases.
If it is PolySilicon: the thermal oxidation goes first around the poly 
grains and
high resistance again.

I think of trying to deposit the Boron doped source layer at lower 
temperature and
for a short time ( O2 flow still is required for Diborane ) and continue 
with drive-in
at 1000C in Nitrogen only. Then remove the Diborane doped source.

Thanks, Bernard

On 8/9/12 7:44 AM, Siva Penmetsa wrote:
> Hi All,
> We are trying to optimise Diborane furnace in a new CVD equipment.
> We have performed few trials(all the souces are gases) at
> Temperature 1000 C
> Diborane Flow rate in the range 40 sccm to 100 sccm
> Oxygen flow rate 2 SLPM
> Nitrogen flow rate is 3 SLPM
> Time 30 minutes
> Instead of decrese in resistance we observed that the resistance 
> incresed to around 500 ohm/sq from around 50 ohm/sq
> We apprecite your experience and inputs on how we can resduce the 
> resisitivity with better Diborane diffussion.
>
> -- 
> Thanks & Regards,
> *Siva Prasad Raju Penmetsa*
> /Senior Facility Technologist/
> National Nano Fabrication Center
> /Indian Institute of Science(IISc)/
> Bangalore, India 560 054
>
>
>
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