Eric Eisenbraun

Device‐quality copper using chemical vapor deposition of β‐diketonate source precursors in liquid solution

Device‐quality copper films were produced by chemical vapor deposition from copper(II) β‐diketonate precursors using a liquid delivery approach. This liquid delivery method exploits the high solubility of copper(II) β‐diketonate precursors in selected solvents, such as isopropanol and ethanol, to provide highly accurate, reproducible, and controllable flow rates of precursor and solvent mixtures to the reaction zone. The approach was successfully employed to produce high‐quality copper files from predetermined mixtures of bis(hexafluoroacetylacetonato) copper(II) and ethanol or isopropanol. Plasma‐assisted chemical vapor deposition (PA‐CVD) was used with substrate temperatures of 160–170 °C, reactor working pressures of 1.0–1.7 Torr, hydrogen flow rates between 500 and 1200 cc/min, and hydrogen plasma power density ranging from 0.13 to 0.25 W/cm2. The films were subsequently characterized by Rutherford backscattering spectroscopy, cross‐section SEM (scanning electron microscopy), and a four‐point resistiv...

Hydrogen plasma-enhanced atomic layer deposition of copper thin films

The growth of plasma-enhanced atomic layer deposition (PEALD) grown copper films appropriate for nanoscale electronics applications is reported. Self-limiting PEALD copper growth behavior, employing copper(II) acetylacetonate and atomic hydrogen as reactants, was observed. Deposition of continuous layers as thin as 10 nm was achieved on TaN, Ru, and SiO2 substrates in a temperature range between 85 and 135 °C. A copper purity greater than 95 at. %, as measured by Auger electron spectroscopy, was observed. For a 30 nm thick film, PEALD copper resistivity was 5.3 μΩ cm on TaN and 8.8 μΩ cm on Ru. Conformal depositions have been achieved over high aspect ratio (∼5:1) structures.

Comparative study of the effects of thermal treatment on the optical properties of hydrogenated amorphous silicon-oxycarbide

Findings are presented from a systematic study of the effects of postdeposition thermal treatment on the optical characteristics of hydrogenated amorphous silicon-oxycarbide (a-SiCxOyHz) materials. Three different classes of a-SiCxOyHz films: SiC-like (SiC1.08O0.07H0.21), Si-C-O (SiC0.50O1.20H0.22), and SiO2-like (SiC0.20O1.70H0.24), were deposited by thermal chemical vapor deposition. The effects of thermal annealing on the compositional and optical properties of the resulting films were characterized using Fourier-transform infrared spectroscopy, x-ray photoelectron spectroscopy, nuclear reaction analysis, and spectroscopic ultraviolet-visible ellipsometry. As the Si-C-O system evolved from a SiC-like to SiO2-like matrix, its refractive index and optical absorption strength decreased, while its optical band gap increased. Thermal annealing between 500 and 1100 °C resulted in hydrogen desorption from and densification of the a-SiCxOyHz films. Concurrently, thermally induced changes were also observed for...

Atomic layer deposition growth of a novel mixed-phase barrier for seedless copper electroplating applications

A novel plasma-enhanced atomic layer deposition-grown mixed-phase/nanolaminate Ru–TaN barrier has been investigated, and it was confirmed that the copper diffusion barrier and direct-plate characteristics of the mixed-phase barrier can be modulated by varying the metal ratio in the film. This liner was subsequently optimized to yield a composition that combines the robust barrier properties of TaN with direct-plate characteristics of Ru. It was found that the deposited multicomponent system consists of individual crystalline and amorphous phase regions distributed across the barrier. The resulting optimized mixed-phase barrier was found to exhibit excellent copper diffusion barrier characteristics in layers as thin as 2 nm. A high degree of (111) texture (>84%) was observed for the direct-plated copper on this Ru–TaN barrier, which was very similar to the electroplated Cu deposited on a physical vapor deposition copper-seed control sample. Additionally, the filling characteristics in sub-50-nm features we...

Enhanced growth of device-quality copper by hydrogen plasma-assisted chemical vapor deposition

A hydrogen plasma‐assisted chemical vapor deposition (PACVD) process has been developed for the growth of device‐quality copper films on large‐area substrates. The process takes advantage of the high concentration of reactive hydrogen species present in the low‐power plasma to enhance the clean reduction of copper β‐diketonate precursors such as bis(hexafluoroacetylacetonato)copper(II). Copper films were produced at substrate temperatures of 160–170 °C, reactor working pressures of 1.3–1.7 Torr, hydrogen flow rates between 700 and 1200 cc/min, and hydrogen plasma power ranging from 15 to 30 W (with an equivalent power density of ∼0.10–0.25 W/cm2. The films were characterized by x‐ray photoelectron spectroscopy, Rutherford backscattering spectroscopy, scanning electron microscopy (SEM), and cross‐section SEM. These studies indicate that PACVD processes pure, dense, highly uniform films, and allows conformal step coverage and complete hole filling of patterned test structures. Growth rates over large‐area s...

High aspect ratio Bosch etching of sub-0.25μm trenches for hyperintegration applications

The ability to predict and optimize the effects of the process parameters during silicon dry etching is vital for the fabrication of emerging hyperintegration technologies, as well as many microelectromechanical systems and integrated circuit devices. This article outlines the establishment of reactive ion etching protocols for fabrication of high aspect ratio trenches with minimum scalloping and undercut, employing the Bosch process. High aspect ratio submicron trench array patterns were transferred into silicon substrates using a Unaxis Versalock deep reactive ion etch tool equipped with a time multiplexed plasma etch/passivation cycle scheme which uses an inductively coupled plasma etcher. Through careful optimization of Bosch etch process conditions, successful etching of high aspect ratio (20:1) 170nm trench features was achieved.

Photoluminescence in erbium doped amorphous silicon oxycarbide thin films

Photoluminescence (PL) in Er-doped amorphous silicon oxycarbide (a-SiCxOy:Er) thin films, synthesized via thermal chemical vapor deposition, was investigated for carbon and oxygen concentrations in the range of 0–1.63. Intense room-temperature PL was observed at 1540 nm, with the PL intensity being dependent on the carbon and oxygen content. The strongest PL intensity was detected for a-SiC0.53O0.99:Er when pumped at 496.5 nm, with ∼20 times intensity enhancement as compared to a-SiO2:Er. Broadband excitation in the visible was observed for a-SiC0.53O0.99:Er. Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy analyses suggest that the formation of Si–C–O networks plays an important role in enhancing the Er optical activity in a-SiCxOy:Er films.

Low temperature inorganic chemical vapor deposition of Ti–Si–N diffusion barrier liners for gigascale copper interconnect applications

A new low temperature inorganic thermal chemical vapor deposition process has been developed for the growth of titanium–silicon–nitride (Ti–Si–N) liners for diffusion barrier applications in ultralarge scale integration copper interconnect schemes. This process employs the thermal reaction of tetraiodotitanium (TiI4), tetraiodosilane (SiI4), and ammonia (NH3) as, respectively, the individual Ti, Si, and N sources. Ti–Si–N films were successfully grown over a broad range of deposition conditions, including wafer temperature, process pressure, and TiI4, SiI4, and NH3 flows ranging, respectively, from 350 to 430 °C, 0.1–1 Torr, and 2.5–8.0, 2.5–12.5, and 100–250 sccm. Film stoichiometry was tightly tailored through independent control of the Ti, Si, and N source flows. Film properties were characterized by x-ray photoelectron spectroscopy, Rutherford backscattering spectrometry, transmission electron microscopy, scanning electron microscopy, x-ray diffraction, and four-point resistivity probe. Resulting find...

Profile simulation of conformality of chemical vapor deposited copper in subquarter-micron trench and via structures

Copper profile evolution in ultralarge scale integration via and trench structures was investigated for thermal low pressure, low temperature, chemical vapor deposition (LPCVD) from CuI(tmvs)(hfac). The investigation examined copper profiles in specialized cantilever structures as a function of systematic changes in key processing conditions, namely, substrate temperature, precursor flux, and hydrogen reactant flow. Resulting experimental observations from cross section scanning electron microscopy were incorporated in a fast analytical simulator, using a two-dimensional adsorption/re-emission model, to simulate copper profile evolution. The deposition profiles were simulated using a single rate limiting precursor model. A comparison of simulation results and actual experimental profiles for thermal LPCVD copper showed that species re-emission within the via and trench structures play a critical role in achieving conformal step coverage and complete filling. In additional, precursor flux and substrate tem...

Low temperature metalorganic chemical vapor deposition of conformal silver coatings for applications in high aspect ratio structures

A low temperature metalorganic chemical vapor deposition process has been developed for the growth of conformal silver coatings for applications in reflective mirror arrays, computer chip metallization, and superconducting wire and cable technologies. The process employed the silver source precursor Ag(COD)hfac, where COD=1,5-cyclooctadiene and hfac=1,1,1,5,5,5-hexafluoro 2,4-pentanedionate. Silver films were deposited at wafer temperature, source temperature, and processing pressure in the range of, respectively, 160–240 °C, 80–150 °C, and 0.5–5 Torr. Experiments were carried out in the presence of either argon or hydrogen as coreactant. The resulting films were characterized by Rutherford backscattering spectrometry, x-ray photoelectron spectroscopy, x-ray diffraction, and cross-section scanning electron microscopy. These investigations indicated that the silver films were pure, highly specular, and exhibited excellent conformality in 180 nm wide trench structures with 7:1 aspect ratio.