Posted by Roger Brennan (188.8.131.52) on January 12, 2011 at 17:13:02:
In Reply to: Dopant concentration posted by JACK on January 10, 2011 at 23:37:37:
Spreading resistance profiling (SRP) is a good way of determining the amount of phosphorus in the resultant silicon layer formed. If a single crystal layer is formed, the a plot of carrier concentration - depth will be about the same as the phosphorus concentration depth IF THE PHOSPHORUS CONC IS NO GREATER THAN ~5e19 cm-3. If the concentration is higher, no all the phosphorus is electrical active. If the layer formed is poly, SRP will give you a reasonable resistivity value but the carrier concentration calculated will be under-reported due to the lower carrier mobility of the poly.
SIMS (generally more expensive) will give you the phosphorus concentration if it is > ~1e15 cm-3. SIMS doesn't care whether the phosphorus is active or not but keep in mind that in nearly all cases, it is only the electically active that does you any good.
For calculating ratios, the density of silicon is ~5E22cm-3
As to what recipe to use, I do not know. As I understand it, you have vapor pressures, temperatures, and equipment variables to consider. Perhaps the equipment manufacture can give you some guidelines. Years and years ago, Applied was VERY helpful but my information is way out of date.
: : : : How can I find the dopant concentration of Phosphorus in Silicon?
: i use gas of Silane and Phosphine using PECVD if i use
: SiH4 (5% diluted in H2) with 20 SCCM as silane flow rate and PH3 (0.5% diluted in H2)2SCCm as phosphine flow rate
: i want to know the PH3/SiH4=?? how to calculate it in % and can it be converted in Cm^-3?? pleas help and show me the formula that can handle this problem.
: i will be thankful for your help.