AVS 60th International Symposium and Exhibition
    Electronic Materials and Processing Thursday Sessions
       Session EM+AS+PS+TF-ThM

Paper EM+AS+PS+TF-ThM5
Porosity Scaling Strategies for Low-k Films

Thursday, October 31, 2013, 9:20 am, Room 102 A

Session: Materials and Process for Advanced Interconnects I
Presenter: D.J. Michalak, Intel Corporation
Authors: D.J. Michalak, Intel Corporation
J.M. Blackwell, Intel Corporation
A. Sengupta, Intel Corporation
J.S. Clarke, Intel Corporation
D. Pantuso, Intel Corporation
Correspondent: Click to Email
Mechanical properties of highly porous low-k films are a key manufacturing concern area. Next generation ILD materials will need to be carefully crafted in order to deliver a needed reduction in dielectric constant while also delivering needed mechanical and chemical stability concerns. We have generated a backbone and porogen system with high chemical stability that allows us to control porosity from 0% to 60% volume and achieve dielectric constant values ranging from 3.4 to 1.6. At a given porosity, Young’s modulus values are higher than typical PECVD films, but the amount of improvement decreases as porosity increases. The high porosity and mechanical strength were achieved by tuning the number of reactive crosslinking sites on our oligomeric backbone precursor. Our data are evaluated in light of percolation theory, which sets a theoretical maximum porosity limit for materials made from random mixes of backbone and porogen. Ways around this maximum limit are proposed. Finite Element Modeling of the 0-60% porosity films yielded calculated Young’s modulus values very close to observed values when experimental inputs of porosity, pore size, and pore shape were used. Up to 4x improvement in Young’s modulus is observed for hypothetical structures containing controlled pore size, shape, and order. Stress contour mapping allows a rapid visualization of the mechanisms at play. Material needs for the next generation ILDs will be discussed in light of these data.