Paper PS-WeM5
Interfacial Characterization of Patterned Porous Low-k Nanostructure using Infrared and X-ray Photoelectron Spectroscopy

Wednesday, October 31, 2012, 9:20 am, Room 25

The advanced microelectronic architecture utilizes more conductive Cu interconnect insulated by porous low-k interlayer dieelctrics (ILD) to minimize the overall RC delay. To decrease the dielectric constant, the porosity of organosilicate glass was increased by partial replacing Si-O with Si-C bonds during plasma-enhanced chemical vapor deposition. However, carbon stripping by subsequent plasma etching/patterning processes can make porous low-k interlayer dielectrics, with higher carbon content, more prone to water damage during subsequent wet cleans processes. In this presentation, we report the development of a new characterization approach that utilizes Multiple Internal Reflection Infrared Spectroscopy (MIR-IR) as a sensitive characterization tool to guide the development of cleans-friendly plasma etches with minimal ILD damages. Previously, we have successfully utilized MIR-IR to characterize chemical bonding of hydrogen termination, trace organic adsorption and plasma deposited polymer thin film on silicon wafer surface with sub-monolayer sensitivity. MIR-IR utilizes the silicon wafer (including patterned ILD wafer) itself as an IR waveguide to enable multiple total internal reflections which greatly enhances IR measuring sensitivity. Therefore, MIR-IR possesses a unique capacity of identifying specific functional groups of deposited thin films (sub 10 nm) and monitoring their corresponding reactivity evolution influenced by plasma process. We will discuss new characterization results of post-etch residues formation (fluoro-polymers), plasma etch induced water damage (silanols formation) and oxygen plasma etch of organic thin film on patterned porous low-k nanostructure using MIR-IR spectroscopy, x-ray photoelectron spectroscopy and other surface characterization techniques.