Showing papers by "Jong-Ho Lee published in 2004"

Semiconductor devices having different gate dielectrics and methods for manufacturing the same

Abstract: A semiconductor device includes first and second transistor devices. The first device includes a first substrate region, a first gate electrode, and a first gate dielectric. The first gate dielectric is located between the first substrate region and the first gate electrode. The second device includes a second substrate region, a second gate electrode, and a second gate dielectric. The second gate dielectric is located between the second substrate region and the second gate electrode. The first gate dielectric includes a first high-k layer having a dielectric constant of 8 or more. Likewise, the second gate dielectric includes a second high-k layer having a dielectric constant of 8 or more. The second high-k layer has a different material composition than the first high-k layer.

Dermal substitute consisting of amnion and biodegradable polymer, the preparation method and the use thereof

Abstract: The present invention relates to a dermal substitute comprising the biodegradable polymer such as collagen and the biomaterial such as amnion, the preparation method and the use thereof. Specifically, the present invention provides with an amnion-collagen sponge complex structure prepared by attaching, inserting or incorporating an amnion obtained from placenta to/in collagen. Inventive dermal substitute can be applied to surgery and wound requiring skin graft, for example, severe burns such as second-degree burn, without rejection by immune system. Further, inventive dermal substitute with amnion instead of silicone membrane has several advantages, such as better biocompatibility, anti-inflammatory activity and promoting activity of wound healing and commercial utilization as basement membrane. Also, inventive complex structure can be used as the basic matrix of bio-artificial skin for culturing cells and the biodegradable basic matrix for preparing artificial organs.

Facet evolution in selective epitaxial growth of Si by cold-wall ultrahigh vacuum chemical vapor deposition

Abstract: Si epitaxial layers were selectively grown on local-oxidation-of-silicon-patterned Si (100) substrates by cold-wall ultrahigh vacuum chemical vapor deposition. The Si windows were aligned along the [110] direction on Si (100) surface. As growth temperature increased from 550 to 650 °C, the development of (111) facets was dramatically suppressed, and the Si growth on sidewall facet planes was decreased. It is believed that surface diffusion of Si adatoms plays an important role in the morphological evolution of selective epitaxial growth (SEG). We propose a model to explain our experimental observations, and to clarify the effect of growth temperature on the facet morphology in terms of the surface mass transport and mass accumulation processes on facet surfaces. (211) facet formation between (311) and (111) facets in Si SEG is reported, and the stability of the (211) plane is also discussed. Finally, we investigated the changes in facet morphology with Si layer thickness, which supports our model for the ...

Characteristics of body-tied triple-gate pMOSFETs

Abstract: Body-tied triple-gate pMOSFETs were fabricated using bulk Si wafers and characterized. Process steps to implement the devices are explained briefly. Device characteristics of the triple-gate pMOSFETs were compared with those of the conventional planar channel device. While maintaining low off-leakage currents and threshold voltages similar to those of planar pMOSFETs in the parallel arrayed 30 000 transistors, the body-tied triple-gate MOSFETs showed about 74 mV/dec of subthreshold swing (92 mV/dec for conventional devices) and a drain-induced barrier lowering of 34 mV/V (92 mV/V for conventional devices). It was also addressed that I/sub SUB//I/sub D/ of the body-tied triple-gate is lower than that of the planar channel device.

Semiconductor device including gate dielectric layer formed of high dielectric alloy and method of fabricating the same

Abstract: A semiconductor device is disclosed comprising an improved gate dielectric layer formed of a high dielectric alloy-like composite together with a method for fabricating the same. The semiconductor device comprises a semiconductor substrate and a gate dielectric layer consisting essentially of a high-k alloy-like composite containing a first element, a second element, and oxygen (O). The first element is at least one member selected from a first group consisting of Al, La, Y, Ga, and In. The second element is at least one member selected from a second group consisting of Hf, Zr, and Ti. A diffusion barrier is formed on the gate dielectric layer, and a gate is formed on the diffusion barrier.

Thermal stability and decomposition of the HfO2-Al2O3 laminate system

Abstract: The thermal stability of the HfO2–Al2O3 laminate gate stack grown by atomic layer chemical vapor deposition was investigated using medium-energy ion scattering spectroscopy and high-resolution x-ray photoelectron spectroscopy. The laminate structure was maintained up to 800 °C under ultrahigh vacuum conditions, while it was drastically degraded at 850 °C, resulting in silicide formation on the film surface. Dissociated oxygen in the Hf–Al-oxide preferentially diffuses out through the film and desorbing at the surface. Volatile SiO species and Al–O components desorb through the sample surface, while HfO2 contributes to Hf silicide formation on the film surface.

Effect of capping silicon nitride layer and nitrided gate oxide on hump of transistors

Abstract: In this letter, we investigate the effect of capping silicon nitride and nitrided gate oxide on the hump in the sub-threshold slope of various transistors. Silicon wafers having both high- and low-voltage transistors are fabricated. The thin gate oxide is grown by nitric oxidation, while two step process of dry oxidation and low-pressure chemical vapor deposition (LPCVD) is used for the thick gate oxide. Note that the thickness of thin gate oxide is 4.5 nm, and 29 nm for thick gate oxide. It appears that both low-voltage nMOS and pMOS do not show any hump, nor does high-voltage pMOS. The subthreshold hump of high-voltage nMOS depends on process conditions. It shows severe hump without capping silicon nitride layer due to moisture diffusion during thermal anneal after interlayer oxide deposition by LPCVD. It also appears that nitrided oxide is effective to prevent hump by stopping moisture diffusion.

Design Consideration of Body-Tied FinFETs (Ω MOSFETs) Implemented on Bulk Si Wafers

Abstract: The body-tied FinFETs (bulk FinFETs) implemented on bulk Si substrate were characterized through 3-dimensional device simulation. By controlling the doping profile along the vertical fin body, the bulk FinFETs can be scaled down to sub-30 nm. Device characteristics with the body shape were also shown. At a contact resistivity of 1 × 10 -7 Ω cm 2 ,

Isotropic/anisotropic growth behavior and faceting morphology of Si epitaxial layer selectively grown by cold wall ultrahigh vacuum chemical vapor deposition

Abstract: Si epitaxial layers were selectively grown on local oxidation of silicon patterned Si (100) substrates by the cold wall ultrahigh vacuum chemical vapor deposition under various growth conditions. The isotropic/anisotropic growth behavior and the faceting morphology of Si epitaxial layers were systematically investigated. As the growth temperature increased and the Si2H6 flow rate decreased, the lateral overgrowth of Si was reduced, and subsequently the anisotropic selective epitaxial growth (SEG) of Si was enhanced. Depending on growth conditions, the lateral overgrowth was not initiated until the layer thickness exceeded a critical value, and the degree of lateral overgrowth was changed with the layer thickness. These observations strongly imply that the mass transport and accumulation processes on facet surfaces play an important role in the SEG morphological change. Taking both surface mass transport and free energy change into account, a model is proposed to explain our experimental observations, and ...

Design of a 20 nm T-Gate MOSFET with a Source/Drain-to-Gate Non-overlapped Structure

Abstract: eld, resulting in the suppression of the short-channel eects (SCEs). T-gate is used to reduce the gate resistance and to induce more carriers in the non-overlapped region to increase current drivability. The key device characteristics, including internal physics, were investigated by using extensive simulations. Compared to a conventional overlapped structure, the proposed structure has potential for the further scaling down.

Characteristics of ALD HfSiO/sub x/ using new Si precursors for gate dielectric applications

Abstract: We have successfully developed a process for ALD HfSiO/sub x/ that can provide excellent compositional control by using new Si precursors, Si/sub 2/Cl/sub 6/ (HCDS) and SiH[(CH/sub 3/)/sub 2/]/sub 3/ (tDMAS). In addition, comparisons of electrical properties of HfSiO/sub x/ using two Si precursors have been performed. CMOSFET with HfSiO/sub x/ using HCDS results in better reliability characteristics than tDMAS. Superior electron and hole mobility (100% and 90% of universal curve at 0.8MV/cm) are also achieved with HCDS. Consequently, HCDS has the potential to be used as a Si precursor for ALD HfSiO/sub x/.

Threshold Voltage Behavior of Body-Tied FinFET (OMEGA MOSFET) with Respect to Ion Implantation Conditions

Abstract: The body-tied finFET (called OMEGA (Ω) metal oxide semiconductor field effect transistor (MOSFET)) exhibits positive characteristics as a future complementary metal oxide semiconductor (CMOS) device. The Ω MOSFETs have unique features such as high heat dissipation to the Si substrate, no floating body effect, and low defect density, while having the key advantages of the silicon-on-insulator (SOI)-based finFET characteristics. In order to increase the threshold voltages on both the Ω NMOSFET and the Ω PMOSFET while keeping the conventional gate electrodes (n+ polysilicon and p+ polysilicon gates for NMOSFET and PMOSFET, respectively), the device characteristics of the Ω MOSFETs have been characterized with halo ion implantation doses for the Ω NMOSFET and lightly doped drain (LDD) doses for the Ω PMOSFET. It was shown that the VTH adjustment could be partially achieved.

HCI and BTI characteristics of ALD HfSiO(N) gate dielectrics as the compositions and the post treatment conditions

Abstract: For the first time, we evaluate the HCI and BTI degradation of ALD HfSiO(N) gate dielectrics as the compositions and the post annealing conditions. The HCI and PBTI degradation are minimized at Hf to Si cycle ratio of 3 to 1 (Hf/(Hf+Si) = 0.75) and the post reoxidation annealing suppresses both degradations. It is believed that the HCI and PBTI degradation are related to the electron traps in the gate oxide. However, NBTI degradation is negligibly small compared to PBTI degradation. This indicates that the positive fixed charge generation or hole traps are not significant in ALD HfSiO(N) gate dielectrics.

Change of blood viscosity and deformability in oral squamous cell carcinoma patients.

Abstract: J. Kor. Oral Maxillofac. Surg. 2004;30:181-185) 명 훈 110-749 서울시종로구연건동 28번지 서울대학교치과대학구강악안면외과학교실 Hoon Myoung Department of OMFS, College of Dentistry, Seoul National University, Yeon-gun dong 28, chong-ro ku, Seoul, 110-749, Korea Tel : 82-2-760-3059 Fax : 82-2-766-4948 E-mail : myoungh@snu.ac.kr CHANGE OF BLOOD VISCOSITY AND DEFORMABILITY IN ORAL SQUAMOUS CELL CARCINOMA PATIENTS Pil-Young Yun, Hoon Myoung, Jong-Ho Lee, Pill-Hoon Choung, Myung-Jin Kim Department of Oral and Maxillofacial Surgery, College of Dentistry, Seoul National University Malignant tumor have hypoxic cell fraction, which makes radio-resistant and hypoxia in tumor is a result from the blood flow decrease caused by increase in blood flow resistance. Blood viscosity increase is major factor of increased blood flow resistance and it could be attributed to the decrease in blood deformability index. For the evaluation of the change of blood viscosity and blood deformability in oral squamous cell carcinoma, we perform the test of the change of those factors between the normal control group and oral squamous cell carcinoma cell patient group. Relative viscosity measured against distilled water was 5.25±0.14 for normal control group, and 5.78±0.26 for the SCC patient group and there was statistical significance between the groups. However, there was no significant difference between the groups in blood viscosity between the groups by tumor size (T1+T2 vs T3+T4). Also, there was no significant difference between the normal control group and SCC patient group in blood deformability index and between the groups by tumor size (T1+T2 vs T3+T4). Increase in blood viscosity was confirmed with this study and it can be postulated that modification blood viscosity might contribute to decrease of hypoxia fraction in oral squamous cell carcinoma, thus improve the effect of radiotherapy and it can be assumed that the main factor of blood viscosity increase is not decrease of blood deformability in oral squamous cell carcinoma.

Functional reconstruction of dento-palatal and maxillary defect using staged operation of prefabricated scapular free flap and dental implants.

Abstract: J. Kor. Oral Maxillofac. Surg. 2004;30:301-307) 김 명 진 110-749 서울시종로구연건동 28번지 서울대학교치과대학구강악안면외과학교실 Myung-Jin Kim Department of OMFS, College of Dentistry, Seoul National University, Yeon-gun dong 28, Jongno-Gu, Seoul, 110-749, Korea Tel : 82-2-760-2632 Fax : 82-2-766-4948 E-mail : myungkim@plaza.snu.ac.kr FUNCTIONAL RECONSTRUCTION OF DENTO-PALATAL AND MAXILLARY DEFECT USING STAGED OPERATION OF PREFABRICATED SCAPULAR FREE FLAP AND DENTAL IMPLANTS Jong-Ho Lee, Myung-Jin Kim, Jong-Chul Park, Yung-Soo Kim*, Kang-Min Ahn, Jun-Young Paeng, Sung-Min Kim**, Hoon Myoung, Soon-Jung Hwang, Byoung-Moo Seo, Jin-Young Choi, Pill-Hoon Choung Dept. of Oral and Maxillofacial Surgery, *Dept. of Prosthodontics, College of Dentistry, Seoul National University, **Dept. of Oral and Maxillofacial Surgery, College of Dentistry, Kangnung National University The flap considered at first for the reconstruction of large maxillary defect, especially mid-face defect, is scapular free flap, because it provides ample composite tissue which can be designed 3-dimensionally for orbital, facial and oral reconstruction. In case of maxillary defect involving hard palate, however, this flap has some limitations. First, its bulk prevents oral function and physio-anatomic reconstruction of nasal and oral cavity. Second, mobility and thickness of cutaneous paddle covering the alveolar area reduce retention of tissue-supported denture and give rise to peri-implantitis when implant is installed. Third, lateral border of scapula that is to reconstruct maxillary arch and hold implants is straight, not U-shaped maxillary arch form. To overcome these problems, new concept of step prefabrication technique was provided to a 27-year-old male patient who had been suffering from a complete hard palate and maxillary alveolar ridge defect. In the first stage, scapular osteomuscular flap was elevated, tailored to fit the maxillary defect, particulated autologous bone was placed subperiosteally to simulate U-shaped alveolar process, and then wrapped up with split thickness skin graft(STSG, 0.3mm thickness). Two months later, thus prefabricated new flap was elevated and microtransferred to the palato-maxillary defect. After 6 months, 10 implant fixtures were installed along the reconstructed maxillary alveolus, with following final prosthetic rehabilitation. The procedure was very successful and patient is enjoying normal rigid diet and speech.