Kathleen Dunn

Compositional and structural changes in LiNbO3 following deep He+ ion implantation for film exfoliation

The physical mechanism of He-ion-based exfoliation in Z-cut LiNbO3 is investigated. Rutherford backscattering/channeling, nuclear-reaction analysis, and transmission electron microscopy are used to examine the compositional and structural changes caused by deep ion implantation followed by thermal annealing. Lattice disruption, He-bubble formation, and Li depletion are observed in the implantation region, as well as the onset of exfoliation. The implications of these observations for the crystal ion slicing method are discussed.

Atomic Layer Deposition of Tantalum Nitride on Organosilicate and Organic Polymerbased Low Dielectric Constant Materials

A previously developed metal-organic atomic layer deposition (ALD) tantalumn nitride (TaN x ) process was employed to investigate the growth ofn TaN x liners on low dielectric constant (low-k) materials forn liner applications in advanced Cu/low-k interconnect metallization schemes.n ALD of TaN x was performed at a substrate temperature of 250°C byn alternately exposing low-k materials ton tertbutylimido-tris(diethylamido)tantalum (TBTDET) and ammonian (NH 3 ), separated by argon purge steps. The dependence ofn TaN x film thickness on the number of ALD cycles performed onn both organosilicate and organic polymer-based low-k materials was determinedn and compared to baseline growth characteristics of ALD TaN x onn SiO 2 . In order to assess the effect of the deposition ofn TaN x on surface roughness, atomic force microscopy (AFM)n measurements were carried out prior to and after the deposition ofn TaN x on the low-k materials. The stability of the interfacen between TaN x and the low-k materials after thermal annealing atn 350°C for 30 minutes was studied by examining interfacial roughness profilesn using cross-sectional imaging in a high-resolution transmission electronn microscope (HR-TEM). The wetting and adhesion properties of Cu/low-k weren quantified using a solid-state wetting experimental methodology aftern integration of ALD TaN x liners with Cu and low-k dielectrics.

Enhancement of Copper Wetting via Surfactant-Based Post-Treatment of Ultra-Thin Atomic Layer Deposited Tantalum Nitride Liners

The influence of surfactant-based liner post-treatment on the wetting and nucleation characteristics of ultra-thin copper (Cu) films has been examined, employing ultra-thin atomic layer deposited (ALD) tantalum nitride (TaN x ) as liner material. This surfactant-based posttreatment consists of in-situ exposure of the liner to a metal-organic source containing a low surface free energy metal (Sn) surfactant, which is a potential candidate for enhancing the wetting of Cu on liner surfaces and subsequently suppressing island-type growth of Cu, due to both the high atomic volume and low surface free energy of the surfactant relative to Cu. A methodology involving thermally-enhanced de-wetting of Cu, promoted by annealing Cu/liner stacks in a forming gas (95% Ar, 5% H 2 ) ambient under several applied thermal budgets (annealing at 350°C for 30 minutes, and at 600°C for 4, 12, and 48 hrs, respectively), was utilized to both elucidate and quantify the wetting properties of Cu on liners, via detailed analyses of the surface morphology of annealed stacks by atomic force microscopy (AFM) and scanning electron microscopy (SEM). By comparing stacks containing ALD TaNx liners to those that contain post-treated ALD TaNx liners, this method allowed an evaluation of the effectiveness of surfactant-based liner surface post-treatments in inhibiting Cu de-wetting.

Conductive Carbon Nanotubes for Semiconductor Metrology

This paper presents an evaluation of e-beam assisted deposition and welding of conductive carbon nanotube (c-CNT) tips for electrical scanning probe microscope measurements. Variations in CNT tip conductivity and contact resistance during fabrication were determined as a function of tip geometry using tunneling AFM (TUNA). Conductive CNT tips were used to measure 2D dopant concentration as a function of annealing conditions in BF2-implanted samples.

Emerging Nanoscale Interconnect Processing Technologies: Fundamental and Practice

The prospects for Gigascale integration and beyond are hindered, in the near term, by increasingly higher RC delays in global and semi-global electrical interconnect systems. Long-term, signal transmission delays are projected to become significantly more challenging due to fundamental limits imposed by the basic laws of physics. As feature sizes shrink below the mean free path for electron scattering in conventional metal wires, surface scattering, which is defined as the scattering of electron waves from the boundaries of ultra narrow conductors, severely hinders electronic conductivity and stands as a major roadblock to Moore’s Law at the most fundamental level.