As feature sizes continue to shrink well beyond the 7 nm node, understanding the delicate balance present in the chemical mechanical planarization (CMP) process is of utmost importance. In order to achieve high through-put and defect-free CMP processes it is critical to develop predictive analytical techniques that directly correlate to macroscopic STI CMP performance metrics (i.e. oxide/nitride removal, defectivity, and dishing/erosion). This work employed a suite of techniques to monitor the CeO2 nanoparticle interfacial redox processes in the presence of structurally diverse rate modulating additives. Specifically, utilizing a UV–vis spectroscopic technique, the Ce3+/Ce4+ ratio in the presence of different slurry additives was monitored and proved to directly correlate to removal rate performance (i.e. an increase in Ce3+/Ce4+ ratio shows an increase in rate). This finding coupled with the rate of dissolved O2 evacuation and a modified QCM technique determined the mode of interaction/adsorption which validates that the mechanism of oxide removal does not strictly depend on redox capacity, but also depends on the dynamic O2 equilibrium at the CeO2 nanoparticle surface. It was determined that the modulation of oxide removal was directly related to the distribution of interactions (i.e. steric vs redox) and was highly dependent on the slurry additive functionality.

Supramolecular nanocomposite materials have emerged as a leading interdisciplinary research area that exploits synergistic relationships at the nanoscale to enhance the properties (mechanical and chemical) of nextgeneration biopolymeric materials. Hydrogels synthesized from natural biopolymers have emerged because of their intrinsic properties such as noncytotoxicity and biodegradability as well as their well-defined threedimensional, noncovalent network that is ideal for modification and functionalization. Therefore, it is critical to develop a mechanistic understanding tailored to the nuances involved in the interactions of the biopolymer scaffold with the functional additives present in these complex matrixes. This work will discuss the strategic design of hydrogels placing emphasis on the selection of the biopolymer network and the critical role that the incorporation of additives such as biomimetic cross-linking agents (lactones/amino acids) and antimicrobial nanoparticles (NPs) has on the properties and responsiveness of the final nanocomposite. Results have shown that the hydrogen bonding capacity of the biomimetic additives and antimicrobial agents (i.e., AgNPs) impacts the packing density of the hydrogel network and therefore modulates the resultant swellability. Furthermore, the addition of Ag-coated TiO 2 NPs (Ag/TiO 2 NPs) and biomimetic additives provided antimicrobial activity along with enhanced closure rates of simulated wounds in adult human dermal fibroblasts.

The Chemical Mechanical Planarization (CMP) process can cause various defects, and they can be classified as mechanical (i.e., scratching), chemical (i.e., corrosion), or physiochemical (i.e., adsorbed contaminants) according to the mechanism of formation. Traditionally, a contact cleaning method involving a poly-vinyl alcohol (PVA) brush is used to transfer cleaning chemistry to the substrate of interest as well as provide the necessary mechanical energy for defect removal. While this process is effective in contaminant removal its reliance on shear forces can induce secondary defect modes, such as scratching. To minimize the aforementioned induced defectivity during contact p-CMP processes, the implementation of non-contact modalities has become of the utmost importance. This work will focus on the rationale design of p-CMP cleaning systems for emerging materials such as SiC, carbon-doped oxides, and metals. “Soft” cleaning chemistry structure (i.e., shape and charge), and processes play a critical role in cleaning efficacy under low stress conditions.

As integrated circuit (IC) technology continues to advance, the challenge to extend Moore’s law without sacrificing power density and energy efficiency is critical. One method of achieving these goals is through the utilization of Chemical Mechanical Planarization (CMP) to achieve surface planarity down to angstrom level uniformity. Current IC architecture relies on the integration of Cu wiring into Si (i.e., TEOS) substrates to provide effective power transfer. However, this traditional design is limited in efficiency for smaller, high-powered devices which require increased insulating properties. To combat these limitations, low resistivity metals (i.e., Ta, TaN, Mo, etc.) are incorporated for their inherent resistance to electromigration. More specifically, Mo has become increasing attractive due to the metal’s thermal stability and compatibility with Cu to serve as an efficient diffusive barrier. These ideal characteristics ultimately lead to the challenge of increased hardness resulting from inherent inert properties leading to the inhibition of effective CMP processes. To overcome this challenge, Mo-CMP involves the use of harsh polishing conditions consisting of high pressure-velocity coupled with complex slurry dispersions containing aggressive redox chemistry (i.e., KMnO4, KIO3, APS, etc.) and high abrasive nanoparticle content (i.e., Al2O3, SiO2, etc.). More specifically, the utilization of harsh oxidizers and alkaline conditions results in a metal oxide film ideal for effective material removal rate (MRR). However, it is with the implementation of these conditions that ultimately results in the generation of surface defects (i.e. scratching, pitting, etching, organic residues, galvanic corrosion, etc.) which are detrimental to the performance (i.e., power efficiency, operating frequency, etc.) for next generation IC devices. This work will focus on the investigation into conditions leading to effective MRR in Mo-CMP. More specifically, this work will utilize a suite of dynamic analytical techniques (i.e. atomic force microscopy, scanning electron microscopy, quartz crystal microbalance, contact angle, electrochemical analysis, etc.) to evaluate interfacial reaction mechanisms that lead to the productive modification for the reduction of shear force during polishing. It has been shown that the incorporation of tailored chemistries and the addition of “softer” passivating agents (i.e., polyamines) can result in the formation of surface-active complexes that trigger rapid interfacial redox reactions in H2O2 environments at a more amenable pH. Increasing the chemistry’s surface activity to Mo will result in a decreased Ea limiting the effects of nanoparticle adsorption to reduce CMP induced defectivity without the expense of corrosion events necessary for MRR. Furthermore, the implementation of “softer” passivating agents can reduce the galvanic corrosion effects with Cu which significantly reduce secondary defectivity.

As integrated circuit and logic device feature sizes approach the 3-nm node, limiting induced defectivity during Chemical Mechanical Planarization (CMP) process (polishing and substrate cleaning) is of utmost importance. The CMP process can cause various defects, and they can be classified as mechanical (i.e., scratching), chemical (i.e., corrosion), or physiochemical (i.e., adsorbed contaminants) according to the mechanism of formation. Traditionally, a contact cleaning method involving a poly-vinyl alcohol (PVA) brush is used to transfer cleaning chemistry to the substrate of interest as well as provide the necessary mechanical energy for defect removal. While this process is effective in contaminant removal its reliance on shear forces can induce secondary defect modes, such as scratching. To minimize the aforementioned induced defectivity during contact p-CMP processes, the implementation of non-contact modalities has become of the utmost importance. This work will focus on the rationale design of p-CMP cleaning systems for emerging materials such as SiC, GaN, carbon-doped oxides, and metals. More specifically, “OVER”-cutting and “soft” cleaning processes that balance the modulation of surface reaction kinetics (chemical and adsorption) with advanced low shear force environment will be evaluated. For example, employing supramolecular cleaning chemistries coupled with reactive oxygen species (ROS) generating complexes under megasonic action were evaluated for effective SiC cleaning. Results from a second order kinetic model indicate that processing conditions (i.e., time and power), “soft” cleaning chemistry structure (i.e., shape and charge), and the generation of ROS all play a critical role in cleaning efficacy under low stress conditions in the megasonic field. Utilizing a suite of dynamic analytical techniques (i.e., atomic force microscopy, quartz crystal microbalance, contact angle, zeta potential, and electrochemical analysis, shear force analysis) a correlation between interfacial reaction mechanisms and effective p-CMP cleaning will be presented.