Evidence of a shallow junction formation from plasma enhanced chemical vapor deposition of boron nitride and silicon boron nitride

Abstract

Dielectric constant characterization of plasma-enhanced chemical vapor deposition (PECVD) of boron nitride (BN) and silicon boron nitride (SiBN) films is studied using metal-insulator-semiconductor (MIS) and metal-insulator-metal (MIM) structures. Using the measurement technique of calculating the dielectric constant value from the capacitance, the average dielectric constant value for the BN and SiBN films deposited under similar conditions can vary as much as 40% (from 2.8 to 4.4). Low dielectric constant values are normally observed on MIS structures where the silicon substrate is n-type. Detailed C-V analysis at various test frequencies (100 Hz-1 MHz) shows that the flatband and the threshold voltages shift more than 30 V in n-type and p-type substrate wafers, respectively. These C-V characteristics suggest the formation of a junction at the insulator-substrate interface. This interface junction is probably formed by the boron-rich nitride deposition during the transient period and subsequent boron diffusion to the silicon substrate. Accounting for this p-n junction on n-type substrate wafers, the adjusted dielectric constant for MIS structures on n-type substrate is between 4 and 5, which is the same for MIS structures on p-type substrate and MIM structures.