Yasutoshi Okuno

Verified

Yasutoshi verified their affiliation via an institutional email.

Learn more

Verified

Yasutoshi verified their affiliation via an institutional email.

Learn more

• PhD
• Executive Officer at SCREEN Holdings Co., Ltd.

Positron annihilation was used to probe vacancy-type defects in electrodeposited Cu films after nanosecond pulse laser annealing. For the as-deposited Cu film, we identified the coexistence of two different vacancy-type defects, vacancy clusters (such as V16) and monovacancy-type defects, coupled with impurities. An enlargement in the vacancy size...

As miniaturization progresses, pattern collapse during the drying step of wet cleaning processes has become a critical issue in the semiconductor industry. In this study, we used reactive molecular dynamics simulations to analyze pattern collapse, with a focus on bondings and reactions. To simulate pattern deformation during the drying process of w...

This research focuses on the crucial task of identifying the viscous sublayer in improving wet cleaning processes. Computational fluid dynamics (CFD) is employed to manipulate fluid properties and process parameters for optimizing cleaning efficiency. The research findings encompass the evolution of thickness across the wafer radius, characterizati...

As the semiconductor industry relentlessly reduces device sizes, efficient and precise cleaning processes have become increasingly critical to address challenges such as nanostructure stiction. Gaining insight into the molecular behavior of water and isopropyl alcohol (IPA) on silicon dioxide (SiO2) surfaces is essential for controlling semiconduct...

1. Introduction IPA (iso-Propyl alcohol) has been widely used in semiconductor manufacturing for drying silicon wafer to mitigate water mark and keep the surface clean after wet cleaning process. Then, IPA process has been extended by combining with the other engineering techniques such as surface modification treatment to dry fragile nano-sized Si...

Pattern stiction of nanostructures during drying has become an issue with device miniaturization, and pattern collapse models have been discussed to solve this problem. These models take into account the surface tension of the liquid and the mechanical strength of the structure, but the drying rate, which is effective in suppressing pattern collaps...

Alloying amorphous GeO2 with Y2O3 or related group IIIA oxides is known experimentally to improve its properties as a gate dielectric in field effect transistors. The mechanism of this is studied here by density functional calculations. The metal site coordination is found to be 6–7, by increasing the oxygen coordination to 3 or higher. The alloyin...

2016 Author(s).Alloying amorphous GeO2 with Y2O3 or related group IIIA oxides is known experimentally to improve its properties as a gate dielectric in field effect transistors. The mechanism of this is studied here by density functional calculations. The metal site coordination is found to be 6-7, by increasing the oxygen coordination to 3 or high...

Models of three representative higher Miller index interfaces, Si(310):SiO2, Si(410):SiO2 and Si(331):SiO2, have been built by an ab-initio molecular dynamics method. We show that each interface can be made as a fully bonded network without any defects and has a reasonable electronic structure for use in FinFETs (fin field effect transistors) or ga...

In this paper, a realistic atomic model is used to study the atomic ordering effect on electronic structures of Si0.5Ge0.5. The hybrid density functional theory (DFT), HSE06, is chosen as the methodology. The calculated bandgap and effective masses of Si and Ge at various symmetry points are first validated by the reported experimental data and emp...

A novel gate first integration approach enabling ultra low-EOT is demonstrated. HfO₂ based devices with a zero interface layer and optimized gate-electrode is used to achieve EOT and T_inv values of ˜5 Å and ˜8 Å respectively for both n and pMOS devices. The drive currents at I_off=100 nA/μm with V_DD=1 V is...

A high performance CMOS HK/MG sub 1nm EOT solution is demonstrated. The drive currents at Ioff = 100 nA/μm with VDD = 1 V are 1.25 mA/μm and 0.56 mA/μm for n and pMOS respectively without strain boost. Through a novel process integration design, PMOS EWF roll-off and NBTI problems with EOT scaling are overcome until sub 1nm EOT region. The PMOS -0....

In this paper, a comprehensive work toward the understanding of the stress memorization technique (SMT) is presented. The effects of the SMT upon PMOS and NMOS device performance are investigated and explained. A novel low-cost solution for a maskless SMT integration into advanced CMOS technologies is proposed, and additional device results examini...

This paper presents for the first time the successful integration of laser-only annealing in a high-k / metal gate first process flow with functional ring oscillators. The process has been optimized to limit defect creation, reduce poly-silicon resistance and obtain good capping/high-k intermixing. EOT reduction with less eWF roll-off, excellent de...

In this paper, we have done a comprehensive study of the junction anneal strategy (by spike and/or laser) for advanced technology nodes with Hk/MG and high-k capping film to control the eWF. It has been shown that a low long channel Vth is easily achievable with anneal sequence optimization. In particular with the help of laser which creates more d...

TaCN layers were deposited using metal-organic chemical-vapor deposition for applications as metal gate electrodes in p -type metal-oxide-semiconductor (p MOS ) devices. The films were formed by thermal decomposition of tertiary-amylimido-tris(dimethylamido)tantalum (TAIMATA^®) between 400 and 600 ° C . The composition was dependent on th...

The purpose of this paper is to evaluate the impact of the geometry of embedded Si1−xGex source/drain junctions on the stress field. Stress simulations were performed using TSUPREM4 2D software to further investigate the elastic strain relaxation as a function of Si1−xGex alloy active size, in the regime where no plastic relaxation is present. More...

We discuss several advancements over our previous report (S. Kubicek, 2006): - Introduction of conventional stress boosters resulting in 16% and 11% for nMOS and pMOS respectively. For the first time the compatibility of SMT (stress memorization technique) with high-kappa/metal gate is demonstrated. In addition, we developed a blanket SMT process t...

We are reporting for the first time on the use of simple resist-based selective high-k dielectric capping removal processes of La₂O₃, Dy₂O₃ and Al₂O₃ on both HfSiO(N) and SiO₂ to fabricate functional HK/MG CMOS ring oscillators with 40% fewer process steps compared to our...

The annealing conditions causing an irregular peak in sheet resistance of nickel silicides are investigated. It is found that the irregular rise in sheet resistance occurs at a critical temperature of 750–775°C as a result of agglomeration related to phase transition from NiSi to NiSi2. Experiments on the effect of temperature, heating rate and ann...

Shallow Trench Isolation (STI) is the process of choice for the isolation of the transistors of Complimentary Metal Oxide Semiconductor (CMOS) devices for technology nodes smaller than 0.25 micrometer. Chemical Mechanical Polishing (CMP) process is an essential part of the STI module. Since the 0.13 micrometer technology node the industry standard...

This paper reports on the impact of the pre-epi bake conditions on the epitaxial growth of Si1 xGex Source-Drain (S/D) stressors as studied by p-n junction leakage analysis. It has been demonstrated that the presence of impurity-related (O, C) defects located at the epi/substrate interface, can act as nucleation sites for misfit dislocations, which...

Silicidation process and effects of various kinds of additive metals for the improvement of thermal stability of Ni silicide were examined carefully for the 45 nm node. In order to obtain heat resistant NiSi, introduction of various metal layers introduced to top or bottom (interface of Ni/Si) of Ni on Si were investigated. However, we couldn't hav...

NiSi is a promising material on salicide process. However, the thermal stability of NiSi is still a significant problem. Degradation in sheet resistance of Ni suicide is originated from phase transition from NiSi to NiSi2 and/or agglomeration of the suicide layers. We noticed the phenomenon that the sheet resistance increased irregularly at the tem...

A novel capacitor technology has been developed for 0.15 mum embedded dynamic random access memory (DRAM). Platinum as electrodes and barium strontium titanate (BST) as dielectrics are used in the capacitor. The BST dielectrics is a stack of two layers. The nucleating bottom layer is deposited by sputtering and the top bulk layer is deposited by ch...

http://www.mrs.org/f01-program-c/

Structural properties and electrical properties of the ultra-thin Pt film on the cup-type structure were studied. We found that Pt film was segregated inside the cup-type structure after oxygen ambient anneal above 400 °C. For the cup-type structure, the segregation was occurred by Pt migration from bottom part of the cup structure, the thinner are...

The electrical properties of the Ru/Ta2O5/Ru planar capacitor structure were investigated. It was determined that the leakage current and temperature dependence were improved using a bottom electrode annealed in Ar/H2 mixture ambient. A step-and-terrace structure was obtained on the Ru surface when annealed in Ar/H2 mixture ambient, unlike that obt...

High dielectric constant materials, particularly (Ba,Sr)TiO (BST), have attracted considerable attention for use as the charge storage dielectric in giga-bit scale DRAMs. Signi�cant technical challenges, however, must be overcome to integrate BST capacitors with sub-micron CMOS. For example, during a typical back-end-of-line process ow, the capaci...

A new stack capacitor structure using barium strontium titanate (BST) has been developed for Gbit scale DRAMs. The feasibility of fabrication of this structure using Pt as the electrode material is demonstrated through the use of novel processes. An appropriately placed oxidation resistant barrier and adhesion layers enhance the thermal and physica...

This paper describes influence of the relaxation current in BaxSr(1-x)TiO3 (BST) thin films on dynamic random access memory (DRAM) operation. The relaxation current is a transient content of dielectric leakage currents. In BST thin films (expected to be a cell capacitor dielectric in 256 Mb DRAM and beyond), the relaxation current often displays th...

The thermally oxidized vicinal Si(001)– SiO2 interface was studied by using polarized beam Fourier transform infrared spectroscopy and cross-sectional transmission electron microscopy. We observed an anisotropic absorption of the Si–O–Si stretching mode at the vicinal interface, which is explained with a proposed Si–SiO2 interface model; a single-l...

GaAs layers were grown on etch-patterned (100) GaAs substrates by MOMBE (metalorganic molecular beam epitaxy) using TEGa (triethylgallium) and thermally cracked TEAs (triethylarsine). Morphology and orientation dependencies of the grown facets on the growth temperature (400–630°C) and V/III ratio (2–4) are investigated. Good morphology of grown lay...

Selective area epitaxy (SAE) of GaSb, AlSb and AlGaSb on (001) GaSb substrates patterned with SiO2 films is demonstrated by metalorganic molecular beam epitaxy (MOMBE) using triethylgallium (TEGa), trimethylamine alane (TMAAl) and elemental Sb (Sb4). It is found that the selectivity of GaSb depends strongly on the growth temperature and the flow ra...

Molecular orbital calculations are carried out using the MNDO-PM3 (Modified Neglect of Diatomic Overlap Parametric Method 3) method to study the adsorption of the tri-alkyl metal molecules on the surface of III–V semiconductors. For preliminary considerations, the potential energies between the group III atom and group V atom in a H3III–VH3 molecul...

The MOMBE growth reaction process of GaAs using TEGa and AS 4 is investigated theoretically and the improved MOMBE growth kinetic model is proposed, based on the Robertson model. The variations of the growth rate and the desorbing rate of ethyl-Ga molecules from the surface with substrate temperature and As 4 flux are simulated and it is demonstrat...

An improved growth kinetic model for the MOMBE (metalorganic molecular beam epitaxy) of GaAs and GaSb using TEGa (triethylgallium) is proposed. This model can reproduce simultaneously the experimental curves of the growth rate variation with substrate temperature and group V flux and the desorption rate variation of TEGa and DEGa with substrate tem...

Selective area epitaxy (SAE) of GaSb by metal-organic molecular beam epitaxy (MOMBE) on (OOl)GaSb substrates patterned with SiO2 films is demonstrated using triethylgallium (TEGa) and Sb4. It is found that the SAE strongly depends on the growth temperature and the flow rate of TEGa and is easily achieved at low TEGa flow rates and elevated growth t...

MOMBE (metalorganic molecular beam epitaxy) growth characteristics of Sb containing ternary alloys, InGaSb, and GaAsSb are investigated. In the growth of InGaSb using TEGa (triethylgallium), TMIn (trimethylindium), and Sb 4 (elemental antimony), the enhanced desorption of methyl‐In molecules at a substrate temperature T sub of around 500 °C as well...

MOMBE (metalorganic molecular beam epitaxy) growth of AlSb and AlGaSb using trimethylamine alane (TMAAl), triethylgallium (TEGa) and solid antimony (Sb4) is reported for the first time. The growth rate of AlSb shows a monotonic increase with substrate temperature (Tsub) and a decrease with increasing Sb flux. The activation energy for the AlSb grow...

Step flow growth of GaAs on the vicinal surfaces by gas‐source migration enhanced epitaxy (MEE), the combination of gas‐source molecular beam epitaxy and MEE, is studied with the reflection high‐energy electron diffraction (RHEED) intensity oscillation. It is found that the use of the thermally cracked AsH 3 instead of solid As (As 4 ) as an As sou...

The growth characteristics of antimonide compounds grown by metal organic molecular beam epitaxy (MOMBE) and using trimethylindium, triethylgallium (TEGa), and triisobutylaluminum (TIBAl) as group III sources and As4, Sb4, triethylarsine (TEAs), and triethylstibine (TESb) as group V sources were obtained by measuring growth rates and composition va...

InGaAsP/InP quantum-wire structures are fabricated by focused Ga ion beam implantation onto InGaAs/InP single quantum well (QW) structures. It is found that InGaAsP layers produced by the intermixing of InGaAs/InP QW's by Ga ion implantation and subsequent thermal annealing are nearly lattice matched to the InP substrate. Fabricated quantum-wire st...

AlSb and AlGaSb single crystalline layers have been grown on GaSb substrates by metalorganic molecular beam epitaxy (MOMBE) using trimethylaluminium (TMAl), triisobutylaluminium (TIBAl), triethylgallium (TEGa) and solid antimony (Sb4). Crystalline AlSb films have been obtained using TIBAl, while not when TMAl was used. This is related to the differ...

We report metalorganic molecular beam epitaxial (MOMBE) growth of GaSb and InAsSb using triethylgallium (TEGa), trimethylindium (TMIn), triethylstibine (TESb), and triethylarsine (TEAs). For GaSb growth, the maximum growth rate is observed at a substrate temperature of 500-degrees-C. This is associated with the use of TESb instead of solid Sb, wher...

Surface diffusion of Ga molecules during the MOMBE (metalorganic molecular beam epitaxy) growth of GaAs using TEGa (triethylgallium) was studied by measuring the RHEED (reflection high energy electron diffraction) intensity oscillations on the (001) GaAs vicinal surface. It is found that the obtained diffusion constant values for the MOMBE growth a...

Reflection high-energy electron diffraction (RHEED) intensity oscillations are studied during the growth of GaSb and InAs on GaSb substrates by metalorganic molecular beam epitaxy (MOMBE) using triethylgallium (TEGa) and trimethylindium (TMIn), respectively. For the GaSb growth, the temperature dependence of the growth rate shows a monotonic increa...

GaSb, InSb and InGaSb single crystalline layers have been grown on GaSb substrates, for the first time, by metalorganic molecular beam epitaxy using triethylgallium (TEGa), trimethylindium (TMIn) and solid antimony. GaSb epilayers having mirror surfaces without Ga droplets have been obtained under Sb pressures higher than the particular value, whic...