Search

Thin films of low dielectric constant (κ) materials such as Xerogel (ĸ=1.76) and SilkTM (ĸ=2.65) were implanted with argon, neon, nitrogen, carbon and helium with 2 x 1015 cm -2 and 1 x 1016 cm -2 dose at energies varying from 50 to 150 keV at room temperature. In this work we discuss the improvement of hardness as well as elasticity of low ĸ dielectric materials by ion implantation. Ultrasonic Force Microscopy (UFM) [6] and Nano indentation technique [5] have been used for qualitative and quantitative measurements respectively. The hardness increased with increasing ion energy and dose of implantation. For a given energy and dose, the hardness improvement varied with ion species. Dramatic improvement of hardness is seen for multi-dose implantation. Among all the implanted ion species (Helium, Carbon, Nitrogen, Neon and Argon), Argon implantation resulted in 5x hardness increase in Xerogel films, sacrificing only a slight increase (∼ 15%) in dielectric constant.

The investigation of an alternate approach to nondestructive, nanoscale mechanical imaging for IC interconnect structures is reported. This approach utilizes a heterodyne interferometer based on a scanning probe microscope, also referred to as heterodyne force microscopy (HFM). This interferometer is sensitive to the relative phase difference of the two ultrasonic excitations due to spatial variations in the sample viscoelastic response and enables near-field, phase-sensitive imaging. Proof-of-feasibility demonstrations of this technique are presented for ultrasonic phase-imaging of Al/low-k interconnect structures. Spatial resolution

Experimental investigations are presented regarding the surface-selective molecular selfassembly of fluorinated monochloroalkylsilane of the type (heptadecafluoro-1,1,2,2-tetrahydrodecyl) dimethylchlorosilane (denoted F17) on silicon dioxide (SiO2) and silicon nitride (Si3N4) surfaces. The goal is to investigate the controlled and selective surface self-assembly of these molecules as a potential route for substrate-selective covalent bonding of complex molecular assemblies to semiconductor substrates for on-chip interconnect and device applications. X-ray photoelectron spectroscopy (XPS), x-ray reflectivity (XRR) and atomic force microscopy (AFM) have been used to investigate the selectivity of the F17 self-assembly. Contrary to previous reported results, a high degree of F17 monolayer attachment selectivity is consistently observed between SiO2 and Si3N4 substrates for all three of the aforementioned monolayer characterization methods.

Thin film electroluminescent devices employing zinc sulfide doped with manganese are extensively used for applications in which the weight, brightness and mechanical robustness requirements preclude the use of other types of displays such as cathode ray tubes or liquid crystal displays. The physical, optical and electrical properties of phosphors such as ZnS:Mn can often depend strongly on microstructure, which in turn depends on the growth and processing of the film. For this study, ZnS:Mn layers were fabricated by metalorganic chemical vapor deposition (MOCVD) in the 250°-500°C range on an Al2TiO/ In2SnO5 /glass stack. Selected samples were then subjected to a post-deposition anneal in H2S/Ar at 700°C for up to 4 hours. The microstructure of the ZnS:Mn films was examined by Transmission Electron Microscopy (TEM). For all growth and annealing conditions, the films consisted of columnar grains whose column axis was parallel to the growth direction, and which widened laterally through the thickness of the films. For the as-deposited films, the crystal structure was found to be predominantly 2H structure, with the 8H polytype being identified in the low-temperature ZnS:Mn films. The 700°C post-deposition annealing was found to initiate a solid state transformation to the cubic (3C) ZnS crystal structure. All films contained high densities of stacking faults and microtwins, whose role in the 2H-3C transformation is discussed. Also discussed are initial Ultrasonic Force Microscopy (UFM) results which suggest a correlation between the defect microstructure and the elastic response of the material.

A new characterization tool based on ultrasonic force microscopy (UFM) has been developed to image the nanometer scale mechanical properties of aluminum/low-k polymer damascence integrated circuit (IC) test structures. Aluminum and polymer regions are differentiated on the basis of elastic modulus with a spatial resolution ≤ 10 nm. This technique reveals a reactive-ion etch (RIE)-induced hardening of the low-k polymer that is manifested in the final IC test structure by a region of increased hardness at the aluminum/polymer interface. The ability to characterize nanometer scale mechanical properties of materials used for IC back-end-of-line (BEOL) manufacture offers new opportunities for metrological reliability evaluation of low-k integration processes.