De-carbonization of self-assembled molecular monolayers doping in silicon

Unintentional C-related contamination can be readily introduced into the substrate in self-assembled molecular monolayer doping. These C contaminants can bind with dopants, forming interstitial defects, which will in return electrically deactivate the dopants. This issue will exacerbate when the dopant concentration is low. In this paper, a low temperature oxidation method (550 °C for 30 min) is introduced to remove carbon before the phosphorus dopants are driven into silicon in a rapid thermal annealing process. The samples with and without the pre-oxidation process are characterized by the Van der Pauw, low-temperature Hall effect measurements, and secondary ion mass spectrometry analysis. The results indicate that the surface carbon concentration in silicon is nearly completely removed with the pre-oxidation process, as a result of which the electrical activity of phosphorus is indeed increased.