A two-step low-temperature process for a p-n junction formation due to hydrogen enhanced thermal donor formation in p-type Czochralski silicon

The incorporation of hydrogen into standard p-type Czochralski (Cz) silicon (greater than or equal to 1 Ohm cm) by a 110 MHz plasma treatment at 260 degrees C leads to the formation of an n-type region due to hydrogen enhanced thermal donor (TD) formation in hydrogenated regions of the wafer, if a subsequent annealing in air is applied at 450 degrees C. Spreading resistance probe (SRP) and light beam induced current (LBIC) measurements were used for the experimental analysis. The p-n junction depth, i.e. the counter doping by TDs, depends on the initial doping level of the p-type substrate, and therefore on the post-hydrogenation annealing time. The penetration of the n-type region into the wafer bulk is driven by a rapid hydrogen diffusion. The essential process for a TD generation is the creation of metastable hydrogen molecular species around 260 degrees C and their decay at 450 degrees C.