| AVS 56th International Symposium & Exhibition | |
| Plasma Science and Technology | Monday Sessions |
| Session PS1-MoM |
| Session: | Advanced Interconnect Etch |
| Presenter: | J. Shoeb, Iowa State University |
| Authors: | J. Shoeb, Iowa State University M.J. Kushner, University of Michigan |
| Correspondent: | Click to Email |
Porous dielectric materials offer lower capacitance that reduces RC time delay in integrated circuits. While porosity of the dielectric can be as high as 0.5, the pores open to the surface which are internally connected can offer pathways for reactive species to enter into the porous network resulting in a degraded dielectric constant. The porous low-k materials are typically SiOCH – silicon dioxide with carbon groups, principally CH3, lining the pores. Reactions with the CHx groups can increase the k value of the material. To maintain the low-k value of porous dielectrics, sealing of the surface pores is desirable. Treatment of the porous material with successive He and NH3 plasmas has been successful in sealing the pores1. The He plasma can break Si-O bonds creating dangling bonds on the SiO2 surface while knocking off H atoms from CH3 group which is connected to Si of SiO2 by a Si-C bond. This creates more reactive CHx (x = 1,2) species without significant damage to the substrate. Successive NH3 plasma treatment seals the pore as NHx (x=0,1,2) species passivate previously produced Si forming Si-N bonds and reactive CHx groups adsorbing NHx species to form C-N bonds. A reaction mechanism has been developed for the sealing of a porous carbon doped silica films (SiOCH) in sequentially applied He and NH3/Ar plasmas. The HPEM (Hybrid Plasma Equipment Module) was employed to obtain the ion energy and angle distributions of reactive fluxes from inductively coupled plasmas. These are used as input to the MCFPM (Monte Carlo Feature Profile Module) with which profiles of the low-k materials after the plasma exposures are predicted. Results will be discussed, including validation with data from the literature, for the densification and sealing of pores as a function of pore radius, porosity, interconnectivity, bias voltage and plasma power.
1. A. M. Urbanowicz, et al., Electrochem. Solid-State Lett. 10, G76 (2007).
* Work supported by Semiconductor Research Corp