Hello everybody,

I am working in a project in which I am integrating some piezorresistances
of P-type on N-type substrates. The dopant I am using is a Filmtronics
spin-on dopant, called B-20. I use 1um thermal silicon dioxide as a
difussion mask and  the difussion process consists in a deposition phase of
1 hour at 850ºC and a distribution phase of 1 hour at 950ºC. I use 1um
aluminium layer as metalization and an annealing of 1hour at 450ºC.
After all this process I am having some stability problems. The value of the
integrated resistances vary on time.

Does anybody know which could be the problem? Could anybody help me somehow?

Thank you very much in advance.

Juan-Mari Artola
Microelectronics department
CEIT