Study of oxygen influences on carbon doped silicon oxide low k thin films deposited by plasma enhanced chemical vapor deposition.

Carbon doped silicon oxide SiO(C, H) low k thin films (k∼2.9) deposited by the plasma enhanced chemical vapor deposition technique from trimethylsilane (3MS) and oxygen (O₂) have been studied. Two types of chemical vapor deposition process recipes, namely CVD1 and CVD2 were applied for film deposition. CVD1 is an initial recipe that resulted in films with a uniform deposition rate irrespective of film thickness and a low dielectric constant of about 2.9. However, it suffers from extraordinarily high post particle counts. CVD2 is a modified recipe adopted to address this issue. The main difference between the two recipes is that a pump down step immediately before the film deposition has been omitted in recipe CVD2, and this has successfully reduced the particle counts to a satisfactory level. However when using recipe CVD2, the deposition rate is nonuniform and the dielectric constant is slightly above 3.0, attributed to the residual oxygen in the process step prior to film deposition. In this study we investigate the effects of oxygen incorporation on the properties of SiO(C, H) films. Surface defects and their element composition, film thickness, refractive index, dielectric constant, and chemical bonding analysis of the films have been carried out. The chemical composition and structure of films deposited by recipes CVD1 and CVD2 show very slight differences, and are also slightly nonuniform along the film depth. Although the nonuniformity does not have much effect on the dielectric constants of the SiO(C, H) films, it may pose a potential challenge for these low k films in terms of advanced integration. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]