Hidenori Miyoshi

Theoretical Analysis of Elastic Modulus and Dielectric Constant for Low-k Two-Dimensional Periodic Porous Silica Films

To lower the dielectric constant k of interlayer-dielectric films with two-dimensional pore structures while maintaining their mechanical strength, the influences of pore arrangement on the elastic modulus E and k of the films were investigated. It was found that periodicity in pore structure enhances E with constant k. Periodic porous silica films having a hexagonal arrangement of circular cylindrical pores with k 3 GPa were demonstrated to be feasible at a porosity of 0.614 using a bulk material with a k of 4.0 and E>21 GPa.

Theoretical Investigation of Dielectric Constant and Elastic Modulus of Two-Dimensional Periodic Porous Silica Films with Elliptical Cylindrical Pores

The effects of film shrinkage during the thermal curing of two-dimensional periodic porous silica films on the relative dielectric constant k with respect to the vacuum value and the relative elastic modulus E with respect to the skeletal (pore-wall) value Ew were investigated by theoretical calculations. Two extreme models of the film thickness shrinkage were assumed in the calculation: the constant porosity model and the constant wall volume model. It was found that E/Ew decreased more markedly upon film thickness shrinkage in the constant porosity model than it did in the constant wall volume model. The calculated results were confirmed by the experimental data together with the elliptical cylindrical pore shape. It is shown that the film shrinkage of ultralow-k porous silica films must be suppressed for achieving the higher elastic modulus while keeping the k value constant.

Theoretical Investigation of Dielectric Constant and Elastic Modulus of Three-Dimensional Isotropic Porous Silica Films with Cubic and Disordered Pore Arrangements

The dielectric constant (k) and elastic modulus (E) of self-assembled three-dimensional porous silica films were investigated by analytical and numerical calculations to reveal the relationship between k and E. It was found that cubic pore arrangements have E values higher than those of random pore arrangements and two-dimensional periodic hexagonal pore arrangements for the same k. It was also found that disordered isotropic porous silica films having cylindrical pores with well-controlled pore size distributions exhibit an E vs k relationship similar to that of two-dimensional hexagonal periodic porous silica films. The elastic modulus of the skeletal silica was determined to be 40 GPa from the combination of the calculated results and experimental data on ultralow-k disordered porous silica film with a k value of 2.0 and a modulus of 8 GPa.

In-situ contact formation for ultra-low contact resistance NiGe using carrier activation enhancement (CAE) techniques for Ge CMOS

We first achieved ultra-low NiGe specific contact resistivities (ρ_cs) of 2.3×10^-9Ωcm² and 1.9×10^-8Ωcm², which were both reduced from the best values ever reported by one order of magnitude, for Ge P- and N-MOS, respectively. The keys to the excellent performance were carrier activation enhancement (CAE) techniques using Ge pre-amorphization implant (PAI) or laser anneal (LA) followed by an in-situ contact process. Impact of ultra-low ρ_cs on saturation drive current (Id_sat) was also simulated for ITRS 2015 HP nFinFET.

Theoretical Investigation into Effects of Pore Size and Pore Position Distributions on Dielectric Constant and Elastic Modulus of Two-Dimensional Periodic Porous Silica Films

The effects of the pore size distribution (psd) and pore position distribution (ppd) of two-dimensional (2D) periodic porous silica films on dielectric constant (k) and elastic modulus (E) were investigated by theoretical calculations. It was found that such porous silica films with a wider psd or a wider ppd show lower E value than 2D hexagonal periodic porous silica films with an identical pore size. Careful control of pore structure is necessary for obtaining ultralow-k porous silica films with a high E.

Low nickel germanide contact resistances by carrier activation enhancement techniques for germanium CMOS application

We fabricated and studied nickel germanide (NiGe) contacts on both n- and p-type germanium (Ge) substrates by applying the carrier activation enhancement (CAE) technique. We achieved a high electron concentration of 8.6 × 1019 cm−3 using a P/Sb co-implant and a record-high hole concentration of 8.4 × 1020 cm−3 using a Ge preamorphization implant and a boron implant. We used the circular transfer length method and two-dimensional DC simulation to determine the specific contact resistivity (ρc). Using the CAE technique, we obtained low ρc values of 6.4 × 10−7 Ω cm2 for the NiGe/n+-Ge contact and 4.0 × 10−8 Ω cm2 for the NiGe/p+-Ge contact. Theoretical calculation of ρc shows that, to achieve a ρc of 1 × 10−8 Ω cm2 as required by the International Technology Roadmap for Semiconductors for the year 2015, contacts on p+-Ge need contact process optimization, while contacts on n+-Ge need further CAE improvement and/or Schottky barrier height reduction.

Novel self-assembled ultra-low-k porous silica films with high mechanical strength for 45 nm BEOL technology

Novel ultra-low-k porous silica films were developed by use of a self-assembly technology. The mechanical properties of the porous silica films could be reinforced independently of the dielectric constant by introducing a tetramethyl-cyclo-tetra-siloxane (TMCTS) treatment. High modulus porous silica films, with an elastic modulus of 8 GPa and dielectric constant of 2, can be achieved simultaneously. Ultra-low-k/Cu damascene with sufficient mechanical strength was demonstrated for 45 nm BEOL (back-end-of-line) technology.

Effects of Water Desorption from SiO2 Substrates on the Thickness of Manganese Oxide Diffusion Barrier Layer Formed by Chemical Vapor Deposition

A manganese oxide (MnOx) diffusion barrier layer was formed by chemical vapor deposition (CVD) on SiO2 substrates with or without preannealing. The thickness dependence of the MnOx layer was investigated in relation to the desorption behavior of water vapor from the substrates. A good correlation was found between MnOx thickness and the amount of desorbed water vapor. It is necessary to control the amount of absorbed water in the substrate to form a thin MnOx barrier layer with good thickness reproducibility.

Molecular Orbital Calculation of the Elastic Modulus and the Dielectric Constant for Ultra Low-k Organic Polymers

We propose a new theoretical calculation method for estimating the (Youngs) elastic modulus E as well as the dielectric constant k of low-k films using a molecular orbital method. Co-oligomers of tricyclo[6.2.0.03,6]deca-1(8),2,6-triene (TCDT) and divinylbenzene (DVB) were investigated by applying this new calculation method to evaluate both k and E. It is shown that organic low-k films with k<2.0 and high elastic modulus are synthesized through the copolymerization reactions of TCDT and para-DVB. The molecular orbital method was demonstrated as a powerful tool for designing molecular structures of ultra low-k films with high elastic modulus.

Plasma-enhanced co-polymerization of organo-siloxane and hydrocarbon for low-k/Cu interconnects

A plasma-enhanced co-polymerization technique was developed for low-k/Cu damascene integration on 300 mm wafers. This technique enables us to control dielectric film properties by introducing organo-siloxane and hydrocarbon into a He-plasma. The growth rate of the low-k film derived from divinyl siloxane–benzocyclobutene (DVS–BCB) as a matrix monomer is increased by adding C2H2 as a deposition acceleration monomer and the Youngs modulus was enhanced by adding diisopropenylbenzene (DIPB) or divinylbenzene (DVB) as a reinforcement monomer. Cu damascene interconnects with plasma polymerized low-k films were successfully fabricated on 300 mm wafers.