SFG analysis of the molecular structures at the surfaces and buried interfaces of PECVD ultralow-dielectric constant pSiCOH: Reactive ion etching and dielectric recovery

Abstract

Molecular structures at the surface and buried interface of an amorphous ultralow-k pSiCOH dielectric film were quantitatively characterized before and after reactive ion etching (RIE) and subsequent dielectric repair using sum frequency generation (SFG) vibrational spectroscopy and Auger electron spectroscopy. SFG results indicated that RIE treatment of the pSiCOH film resulted in a depletion of ∼66% of the surface methyl groups and changed the orientation of surface methyl groups from ∼47° to ∼40°. After a dielectric recovery process that followed the RIE treatment, the surface molecular structure was dominated by methyl groups with an orientation of ∼55° and the methyl surface coverage at the repaired surface was 271% relative to the pristine surface. Auger depth profiling indicated that the RIE treatment altered the top ∼25 nm of the film and that the dielectric recovery treatment repaired the top ∼9 nm of the film. Both SFG and Auger profiling results indicated that the buried SiCNH/pSiCOH interface was not affected by the RIE or the dielectric recovery process. Beyond characterizing low-k materials, the developed methodology is general and can be used to distinguish and characterize different molecular structures and elemental compositions at the surface, in the bulk, and at the buried interface of many different polymer or organic thin films.

Probing molecular structures at buried solid/solid interfaces involving low-k materials or polymers in situ nondestructively: a review

“…Similarly, molecular structures at the surface and buried interface of a low-k pSiCOH were examined before and after reactive ion etching (RIE) and subsequent dielectric repair using SFG. It was also found that RIE treatment and repair did not alter the buried pSiCOH interface 47 …”

“…SFG has been successfully applied to investigate the surface and buried interface of low-k thin film coating on silicon 42 – 47 Low-k materials and copper have been introduced to replace silicon dioxide and aluminum as interconnections in high performance integrated circuits to improve resistance-capacitance delay, minimize crosstalk-noise, enhance signal transmission, and reduce power dissipation. Porous organosilicate (pSiCOH) materials have been extensively used as low-k interlayer dielectric materials 48 , 49 .…”

“…SFG has been extensively applied to study surfaces and interfaces, including buried solid/solid interfaces 38 , 39 , 41 – 47 In the following, we will present several examples to demonstrate that SFG can probe buried solid/solid interfaces to elucidate molecular interactions and molecular structures of buried interfaces in situ .…”

Ultraviolet Light-Sensitive Debonding Layer for Reducing Adhesion of Polymer Adhesives for Recycling

“…However, breaking an interface destroys the interfacial interactions, which very likely leads to studying surfaces that are not representative of the original buried interface. Recently, SFG has been employed to study polymer adhesive interfaces and was used to elucidate chemical reactions occurring at the buried polymer/polymer interface in situ in real time. ,, SFG has also been widely used to explore hard/soft interfaces between silica and a variety of polymer materials in situ nondestructively. − More details on SFG theory and experiments will be discussed in the Methods section.…”