Nitrogen-doping of polycrystalline 3C-SiC films deposited by low pressure chemical vapor deposition

摘要

This paper reports the effect of deposition temperature on the deposition rate, residual stress, and resistivity of in-situ nitrogen-doped (N-doped) polycrystalline 3C-SiC (poly-SiC) films deposited by low pressure chemical vapor deposition (LPCVD). N-doped poly-SiC films were deposited in a high-throughput, resistively-heated, horizontal LPCVD furnace capable of holding up to 150 mm-diameter substrates using SiH_2Cl_2 (100%) and C_2H_2 (5% in H_2) precursors, with NH_3 (5% in H_2) as the doping gas. The deposition rate increased, while the residual stress decreased significantly as the deposition temperature increased from 825℃ to 900℃. The resistivity of the films decreased significantly from 825℃ to 850℃. Above 850℃, although the resistivity still decreased, the change was much smaller than at lower temperatures. XRD patterns indicated a polycrystalline (111) 3C-SiC texture for all films deposited in the temperature range studied. SIMS depth profiles indicated a constant nitrogen atom concentration of 2.6x10~(20)m~3 in the intentionally doped films deposited at 900℃. The nitrogen concentration of unintentionally doped films (i.e., when NH3 gas flow was zero) deposited at 900℃ was on the order of 10~(17)/cm~3. The doped films deposited at 900℃ exhibited a resistivity of 0.02 Ω-cm and a tensile residual stress of 59 MPa, making them very suitable for use as a mechanical material supporting microelectromechanical systems (MEMS) device development.