| Achieving the aggressive device performance metrics demanded by the microelectronics industry dictates the use of low dielectric constant ('low-k') insulating materials to reduce the capacitive component of the interconnect-related RC signal propagation delay. In particular, to meet interconnect performance requirements for the 65 nm node and beyond, one approach is to introduce significant levels of porosity into the interlayer dielectric (ILD) films. However, the incorporation of porosity leads to a number of integration challenges, including increased reliability issues due to the open pores distributed on the sidewalls of vias/trenches. The research discussed in this paper demonstrates that it is possible to 'seal' the sidewalls of patterned porous dielectric layers using a specially designed deposition-etch passivation process. The concept of the process is to employ selected organosilcon precursors to deposit fully dense carbon-doped oxide (CDO) type films using plasma enhanced chemical vapor deposition (PECVD) on patterned porous dielectric structures, and then to preferentially plasma etch the material built up on the via floor. In order to ensure sufficient sealing results, several deposition-etch cycles are required.;Based on this concept, a systematic process development project was carried out. The properties of the resulting CDO films are discussed. The integration characteristics of the CDO film with candidate porous low-k material and with a subsequently deposited TaN barrier layer were also investigated. In addition, two unique approaches have been developed for the characterization of the sealing effectiveness of the cycled passivation process. These two approaches are based on spectroscopic ellipsometry and capacitance-voltage techniques. Both use the exposure of the passivated porous material to the vapor of an organic solvent to evaluate the responses of samples to the presence of the solvent vapor. Results from these experiments confirmed that the samples treated using a PECVD CDO-based passivation process were significantly less susceptible to the solvent vapor, indicating that the process developed in this work is a potential solution for dielectric pore sealing applications. |
