Amir Al-Bayati

Effects of UV cure on glass structure and fracture properties of nanoporous carbon-doped oxide thin films

The effects of UV radiation curing on the glass structure and fracture properties were examined for a class of nanoporous organosilicate low dielectric constant films. A detailed characterization by nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy showed significant changes in the glass structure with increasing curing time, marked by the removal of terminal organic groups and increased network-forming bonds following the initial removal of porogen material. The higher degree of film connectivity brought about by an increased cure duration is demonstrated to significantly enhance adhesive fracture properties and to moderately improve cohesive fracture resistance. Explanations for the enhanced fracture behavior are considered in terms of the glass structure. The important role of crack path selection during adhesive and cohesive fracture processes is used to rationalize the observed behavior.

Surface characterization of ion-enhanced implanted photoresist removal

We characterize the chemical constitutents of high dose implanted deep ultraviolet photoresist before and after dual-mode oxygen plasma processing, where a remote rf-plasma source is operated simultaneously with rf bias. Raman spectroscopy indicates that the organic composition of the crust comprises a mixture of sp2 graphite and sp3 diamondlike carbon structures. High dose ion implantation reduces the hydrogen content by about 50 at. % as measured by hydrogen forward scattering and explains the reduced optical emission signal intensity observed during crust removal. The crust thicknesses extracted from the secondary-ion-mass spectroscopy profile correspond well to prior scanning electron microscopy characterization [Kawaguchi et al., J. Vac. Sci. Technol. B (submitted)] and support the existence of a transitional layer between the hardened crust and the underlying photoresist. Angle-resolved x-ray photoelectron spectroscopy analysis of arsenic implanted photoresist shows that dual-mode plasma processing ...

Shallow junction formation by decaborane molecular ion implantation

The formation of P+/N shallow junctions for 0.18 μm technology requires the incorporation of dopant atoms, e.g., boron, at a depth of 540±180 A below the surface of the crystal. This is done by implanting boron ions at low energies. Another approach for forming shallow junctions involves, in principle, implanting large molecular ions accelerated to higher energies but with an equivalent low energy per boron atom. Decaborane was implanted at 4 and 7 keV and doses of 1E13 and 1E14 cm−2. Junctions with depth <600 A and sheet resistance of 480 Ω/□ have been demonstrated. Annealed samples were also examined using high-resolution cross-section transmission electron microscopy. Molecular ion implantation of Si using decaborane has been simulated using molecular dynamics at energies between 4 and 1 keV per molecule. The simulation shows local swelling resulting from individual molecular impact, and hydrogen is also implanted into silicon.

TCAD calibration of USJ profiles for advanced deep sub-μm CMOS processes

Abstract For advanced technologies there is a lack of experimental data and calibrated physical models that enable accurate simulation of CMOS technologies down to channel lengths of 100 nm and below. This work aims to develop predictive modeling of ultra shallow junctions (USJ) profiles for state-of-the-art and next generation CMOS devices. Profiles were created by As (0.2–10 keV), B (0.2–10 keV) and BF 2 (1–25 keV) ion implantation and annealed at various times and temperatures including typical drain extension spike anneals. B and BF 2 profiles are investigated with and without pre-amorphization by implantation of Si or Ge. The calibration is based on SIMS and SRP profiles as well as XTEM pictures. The BC code Crystal-TRIM was calibrated for ultra low energy implantation. Annealing is simulated within the pair diffusion framework of the process simulator DIOS, including first order reaction equations for interstitial and dopant clustering and a new model for dose loss, where impurities are stored in a thin surface layer on top of the silicon.

Optimization of P+/N junction formation using solid phase epitaxy for the 100 nm technology node and beyond

P+/N diodes are fabricated using a low energy boron implant followed by solid phase epitaxial (SPE) growth at 600°C. The pre-amorphization step was done using Germanium at either 10 keV or 80 keV, both with a dose of 1 × 1015 ions/cm2. Next, boron was implanted at a range of energies from 0.5 keV to 5 keV. The sheet resistance (Rs) measurements and the secondary ion mass spectrometry (SIMS) analysis from the SPE based diodes showed very good results that meet the Junction depth and the sheet resistance requirements for the 100 nm and 70 nm technology nodes using a 10 keV Ge+ pre-amorphization and sub-keV boron implant. However, these diodes were leaky because of the end of range (EOR) defects positioned within their depletion regions. At higher boron energies (2-5 keV), the remaining EOR defects from the 10 keV germanium pre-amorphization step were positioned closer to the surface and farther from the depletion region. These diodes showed lower leakage current densities by two orders of magnitude and a breakdown voltage greater than -4 V. This highlights the strong relationship between the SPE diode characteristics and the remaining EOR position with regards to the depletion region.

TCAD modeling and experimental investigation of indium for advanced CMOS technology

Indium is a key element in the formation of well, channel, and HALO profiles, especially for very deep sub-μm technologies with gate length below 150nm. Indium (115In+) has the advantage of being a large atom and having a small projected range. Hence ion implanted indium produces steeper profiles than boron, providing that the retrograde doping is maintained after the subsequent annealing steps. Therefore, knowledge of the diffusion behavior of indium is extremely important. In this work, Indium diffusion and dose loss are studied both experimentally and by TCAD simulation. N-type silicon wafers were capped with a 50Å thick SiO2 layer, followed by In+ implantation on an Applied Materials Quantum LEAP™ ion implanter at a range of energies from 50keV to 150keV, and at different doses from 1E13 ions/cm2 to 1E14 ions/cm2. The wafers were then annealed under different annealing conditions reflecting typical well and HALO anneal steps, and for calibration purposes. Calibration of the process simulation was done for indium implantation and diffusion, allowing us to describe Indium implantation and diffusion in general, and quantitatively for special effects such as double peak formation and dose loss. It is shown that the double peak, which appears for an Indium dose higher than 4E13/cm2 and energies higher than 50keV for selected anneal conditions, is strongly related to amorphization and defect distribution after implantation. The dose loss is diffusion limited and therefore controlled by the diffusion coefficients in the region close to the silicon surface.

Effects of e-beam curing on glass structureand mechanical properties of nanoporous organosilicate thin films

Abstract Structural characterization techniques, including solid-state nuclear magnetic resonance and Fourier transform infrared spectroscopies, were used in conjunction with mechanical testing to study the effects of thermally activated electron bombardment curing on organosilicate thin films. The electron beam process produced significant improvements in elastic modulus and fracture resistance while still preserving low dielectric constant. Detailed and quantitative analysis was used to elucidate fundamental curing effects on glass structure, including changes in film composition and local bond rearrangements. Enhancements in fracture properties with curing are shown to be due to increased network bond density resulting from changes in network connectivity coupled with moderate film densification.

Selective silicon processing for advanced ultra shallow junction engineering

As the semiconductor design rules continue to shrink, new device processing issues continue to be identified. One issue facing ultra shallow junction CMOS structures is the contact resistance and silicon consumption for silicide in the active source/drain regions of the device. A sacrificial selective silicon layer for elevating the source and drain (S/D) is considered to be a potential solution to metalization issues for 0.1μm devices and beyond. A production worthy selective silicon process has several key control parameters. This paper presents information on the critical processing parameters such as interface contamination control, and the selective silicon process window. Growth results for a single wafer selective elevated S/D process are also presented.

TCAD simulation in development and fabrication of deep-sub-/spl mu/m devices

In this paper experiences in use and application of TCAD in fabrication environment of deep sub-/spl mu/m semiconductor devices is given. Thereby we do not limit ourselves to standard process and device simulation but we discuss also the extension to parameter extraction, ESD and SER simulations. The main goal is to show how one can get a benefit from TCAD and what should be the expectation regarding accuracy and capability to predict. The limits of TCAD and the current status of 3D process and device simulation are discussed at the end of the paper.

Formation of shallow junctions using decaborane molecular ion implantation; comparison with molecular dynamics simulation

The formation of P/sup +//N shallow junctions requires the incorporation of boron atoms at depths closer to the surface of the crystal. This is done commonly by implanting boron ions at low energies. Another approach for forming shallow junctions involves, in principle, implanting large molecular ions accelerated to higher energies but with an equivalent low energy per boron atom. Molecular ion implantation of Si using decaborane has been simulated using molecular dynamics (MD) at energies between 4 keV and 4 keV per molecule. The simulation shows local swelling resulting from individual molecular impact and hydrogen is also implanted into silicon. Decaborane was implanted at 4 keV and 7 keV at doses of 1E13 and 1E14 cm/sup -2/. Junctions with depth <600 /spl Aring/ and sheet resistance of 480 /spl Omega///spl square/ have been demonstrated.