3D integration technology offers an alternative to traditional packaging designs. In traditional Moore’s law scaling, features are added to the die, with graphics, memory control and logic coprocessors all integrated onto the silicon chip. TSV (through silicon via) processing utilizes vertical electrical interconnects that provide the shortest possible path to establish an electrical connection from the device side to the backside of a die. This indirectly allows continues “Moore”- like scaling while only affecting the device packaging. White light interferometry (WLI) has been used for the measurement of topography, step height and via depth using its short coherence length. The nanometer level resolution of this technique is ideal for TSV measurements in the high aspect ratio vias. In this work, six white light interferometer measurements for TSV processing are discussed along with the importance of these measurements to TSV processing, namely: 1. Post-TSV etch: depth, top CD (TCD) and bottom CD (BCD) 2. Post-TSV liner BCD 3. Post-TSV barrier seed BCD 4. TSV electro-chemically plated (ECP) copper bump step height 5. Post-annealing bump step height 6. TSV CMP dishing These measurement steps have been implemented in-line for advanced technology node TSV process flows at GLOBALFOUNDRIES. The measurements demonstrate 90% correlation to reference metrology and <0.5% repeatability. Cross section SEM was used as a reference for TSV profile and Cu bump measurements while AFM was used as a reference for dishing measurements.
Erbium oxide is a promising candidate for possible applications as Si-based light emitting devices in nanoscale
electronics. The current report presents findings pertaining to the effects of the structural properties of erbium-based thin
films on their photoluminescence characteristics. Erbium metal films were deposited on silicon via electron beam
evaporation followed by thermal oxidation. The effects of post-deposition annealing conditions on the structural and
optical properties of the thin films were examined using a variety of techniques, such as spectroscopic ellipsometry, xray
diffraction, and x-ray photoelectron spectroscopy. It was shown that the thin films evolved as function of thermal
treatment from an Er-rich to an ErO-rich (700°C) to an Er2O3-rich (900°C) phase due to an increase in oxygen
incorporation with higher oxidation temperatures. At temperatures ≥ 1000°C, out-diffusion of silicon from the substrate
led to the formation of erbium monosilicate. Furthermore, the photoluminescence spectra of these various phases were
measured, and the correlation between structural properties and luminescence characteristics will be discussed in this
paper.
We report on blue-white luminescence from amorphous silicon oxycarbide a-SiCxOy≤1.68 (0.25<x<0.36) thin
films, synthesized by thermal chemical vapor deposition (TCVD) process. The luminescence from SiCxOy was found to
exhibit a broad band in the blue-violet to near infrared range (370 - 750 nm), visible to the naked eye in a bright room.
The effects of carbon concentration (8.4 at.% < C < 13.6 at.%) in the material and post-deposition annealing treatments
(Ar and forming gas 5% of H2 ambient up to 1100°C) on the observed luminescence were studied. The emission intensity
slightly decreased with increasing carbon content but was appreciably enhanced in the samples following post-deposition
annealing treatment in forming gas 5% of H2 ambient.
We have previously demonstrated strong room-temperature luminescence at 1540 nm from erbium-doped
amorphous silicon oxycarbide (a-SiCxOyHz:Er) materials. In this study, pertinent details are presented regarding the
role of growth conditions and post-deposition thermal treatment in engineering the structural and optical characteristics
of these novel Si-based materials for optimized luminescence performance. Three different classes of a-SiCxOyHz
materials were synthesized by thermal chemical vapor deposition, as classified by their carbon and oxygen
concentrations: SiC-like; Si-C-O; and SiO2-like. Fourier-transform infrared spectroscopy, x-ray photoelectron
spectroscopy, nuclear reaction analysis, and spectroscopic ellipsometry were used to characterize the effects of thermal
annealing, as performed at temperatures in the range of 500 - 1100°<i>C</i>, on the structural and optical properties of the
resulting films. As the material evolves from the SiC-like, through the Si-C-O, to the SiO2-like matrix, the mass density
and refractive index are found to decrease, whereas the optical band gap actually increases. Thermal annealing also
resulted in hydrogen desorption from and densification of the a-SiCxOyHz films and in an accompanying decrease in optical gap and an increase in film refractive index. This work suggests that silicon oxycarbide could be a promising Si-based
matrix for high-performance Er-doped waveguide amplifiers.
The present investigators have previously reported on strong room-temperature luminescence at 1540 nm from
erbium-doped amorphous silicon oxycarbide (a-SiCxOy:Er) thin films. An enhancement of ~20 times was found for asgrown
SiC0.5O1.0:Er compared to SiO2:Er control samples under continuous wavelength (cw) pumping at 496.5 nm.
Here, we report the effects of post-deposition annealing on the photoluminescence (PL) properties of Er-doped silicon
oxycarbide. The amorphous SiCxOy films were grown by thermal chemical vapor deposition (TCVD) at 800°C and postdeposition annealing was conducted in the temperature range 500-1100°C. The thin films were then implanted with
260keV Er ions and subsequently annealed at 900°C. Strong room-temperature photoluminescence around 1540 nm was
observed, with efficient Er+3 ion excitation occurring for pumping wavelengths ranging from 460 nm to 600 nm.
Modeling of the power dependence of Er luminescence yielded an effective Er excitation cross-section about four orders
of magnitude larger than that for a direct optical excitation of Er+3 ions. Additionally, Fourier transform infrared
spectroscopy (FTIR) studies of post-deposition annealed samples revealed a strong correlation between the Er PL
intensity and the C-O bond concentration in the materials. The work suggests a novel method for achieving efficient Er
luminescence in Si-based materials through controlled engineering of the Si-C-O system.
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