Use of SiBN and SiBON films prepared by plasma enhanced chemical vapor deposition from borazine as interconnection dielectrics

Abstract

Thin films of silicon boron nitride (SiBN) of typical composition Si0.09B0.39N0.51 and silicon boron oxynitride (SiBON) of typical composition Si0.16B0.29O0.41N0.14 were prepared by plasma enhanced chemical vapor deposition and the properties of these films were evaluated with respect to their suitability as interconnection dielectrics in microelectronic fabrication. Films were deposited on 125 mm silicon substrates in a parallel-plate reactor at a substrate temperature of 400°C and a plasma power of 0.5 W/cm2. Boron nitride, for comparison of electrical properties, was deposited from borazine (B3N3H6); silicon boron nitride was deposited from borazine, disilane (Si2H6), and ammonia (NH3); silicon boron oxynitride was deposited from borazine, disilane, ammonia, and nitrous oxide (N2O). Metal-insulator-metal capacitors were fabricated and electrical measurements indicated that all three films had excellent dielectric properties with dielectric constants of 4.1, 4.7, and 3.9 for BN, SiBN, and SiBON, respectively. Tests of conformality indicated that deposition into trenches with an aspect ratio of 4:1 gave conformality greater than 70%. Silicon boron oxynitride was shown to be an excellent barrier to the diffusion of copper. A planar, single level metal-insulator structure was constructed using a SiBN/SiBON insulator with copper metallization.