> dear sir,
> i have deposited aluminum over native silicon dioxide and sintered
 >it at 400 C for 30 minutes. i would like to ask if in this situation
 >aluminum will diffuse through the oxide and form an ohmic contact
 >with underlying silicon.

What actually happens is that Si dissolves into the Al (look at a
phase diagram, ca. 0.3% Si is soluble in Al at 400C) and Al diffuses
into the vacancies.

This forms a highly p+ doped, ohmic contact to bare Si.

Of course, if you have a structure in your Si, e.g. a doped contact,
this interdiffusion will eventually spike through your contact and short
(again, nice and ohmic) to your substrate.

--
Klaus Beschorner
Metron Technology, European Legends Product Manager
Drosselweg 6,71120 Grafenau,Germany. Tel +49-7033-45683