ANOMALOUS LOW-TEMPERATURE DOPANT DIFFUSION FROM IN-SITU DOPED POLYCRYSTALLINE AND EPITAXIAL SI LAYERS INTO THE MONOCRYSTALLINE SI SUBSTRATE

In situ phosphorous-doped Si layers have been deposited in three diffe rent ways: (i) by low-pressure chemical vapor deposition (CVD) at 615- degrees-C resulting in polycrystalline Si; (ii) by radio-frequency pla sma-enhanced CVD at 250-300-degrees-C resulting in either epitaxial Si , or (iii) in amorphous Si which is subsequently crystallized at 600-d egrees-C, resulting in epitaxially regrown Si. From secondary ion mass spectrometry and spreading resistance profile measurements, the P app ears in cases (i) and (iii) to be diffused into the underlying substra te across several hundreds of nanometers, much further than normal dif fusivities would forecast. An explanation of this anomalous behavior, based on precipitation of P causing supersaturated self-interstitial c oncentrations is proposed.