Surface Related Phenomena in Integrated PECVD/Ozone‐TEOS SACVD Processes for Sub‐Half Micron Gap Fill: Electrostatic Effects

Surface related phenomena of subatmospheric chemical vapor deposition (SACVD) films were systematically studied on different types of plasma enhanced CVD (PECVD) oxides. The PECVD oxides are part of a new and in situ 2 step gap fill process consisting of a thin PECVD underlayer and a thick SACVD oxide being proposed for advanced ULSI devices. Differences in deposition rates, wet etch rate, surface morphology, and stress‐temperature behavior of SACVD films deposited on PECVD oxide underlayers and bare silicon substrates were evaluated. For the PECVD underlayers which render surface dependence for the SACVD film, various plasma treatments of the underlayer was used to eliminate the effect. An extensive analysis of the surface and bulk properties of these PECVD oxide underlayers suggests that the occurrence of the surface dependence effects can be attributed to the presence of electronegative species such as fluorine on the surface of the PECVD oxide underlayer.