S.I. Lee

Fabrication of the KSTAR superconducting CICC

A superconducting cable-in-conduit conductor (CICC) is adopted for the Korea Superconducting Tokamak Advanced Research (KSTAR) superconducting magnet system which consists of 16 TF coils and 14 PF coils. The KSTAR Magnet system uses two different types of CICCs-Nb/sub 3/Sn cable with Incoloy 908 conduit and NbTi cable with 316LN stainless-steel conduit. A continuous CICC jacketing system is developed for the KSTAR CICC fabrication and the jacketing system uses the tube-mill process, which consists of forming, welding, sizing and squaring procedures. The design specification of CICCs and the fabrication process is described. The welding of the Incoloy 908 strip joint is also discussed. The fabrication results including the geometrical specification and the void fraction will be discussed.

The test facility for the KSTAR superconducting magnets at SAIT

SSTF (Samsung Superconductor Test Facility) has been built with the primary goal of testing the KSTAR TF (Toroidal Field) and PF (Poloidal Field) magnets as well as CICC (Cable-in-Conduit Conductor) and superconducting strands in the most relevant manner. The facility is located at SAIT (Samsung Advanced Institute of Technology) near the KSTAR project home site. Two helium liquefiers of 120 liter/hr capacity have been utilized as refrigerators demonstrating simultaneous double mode operation of refrigeration and liquefaction. A forced flow supercritical helium cooling circuit allows the test facility to be operated at temperatures down to 4.5 K. Other major SSTF components are a large vacuum vessel (6 m diameter and 7.3 m height) with liquid nitrogen temperature shield, data acquisition and control system with EPICS (Experimental Physics and Industrial Control System), current leads, and 50 kA modular power supply with fast dump quench protection circuitry. SSTF has been used for the first test-phase of KSTAR CICC sample. The current status of SSTF as the KSTAR magnet test facility for components and qualification test is presented in detail.

A 6F/sup 2/ DRAM technology in 60nm era for gigabit densities

A novel process technology for 6F/sup 2/ DRAM cell at 68nm design rule was for the first time developed. The cell size is 0.028/spl mu/m/sup 2/, which is the smallest cell size ever reported. ArF lithography with double expose technology and highly selective etching process were used for patterning of critical layers. This 6F cell was made of simple line/space patterns for easy patterning and self-aligned etches to improve process margins. MIM cell capacitor was developed with multi-layer high-k dielectric materials and 11A equivalent Tox and sub-lfA leakage was confirmed.

A FRAM technology using 1T1C and triple metal layers for high performance and high density FRAMs

Recently, ferroelectric random access memory has drawn a great deal of attention due to inherent properties such as nonvolatility, long retention time, high endurance, fast access time, small cell size compared to DRAM cell size in principle, and strong resistance to /spl alpha/-particle and cosmic ray irradiation. None of the available commercial memories meet all of the properties of the ferroelectric memory. Although ferroelectric memory has inherent good properties, full utilization of these properties has not yet been realized. Commercially available products are limited to low densities. The commercially available ferroelectric memory uses a 2T2C (two transistor-two capacitor) structure with single level metal instead of a 1T1C (one transistor-one capacitor) structure with multiple metal layers which is believed to be essential for mega-bit or giga-bit density memory. In this paper, an integration technology for high performance and high density FRAMs is developed using a 1T1C robust capacitor in a COB (capacitor over bit line) structure with triple metallization processes. The technology developed in this paper is evaluated with an experimental 4 Mb FRAM, which is the highest FRAM density developed to date.

Heteroepitaxial growth of Y2O3 films on Si(100) by reactive ionized cluster beam deposition

Abstract Heteroepitaxial Y 2 O 3 films on Si(100) have been grown by the technique of reactive ionized cluster beam (ICB) deposition. The composition of deposited film is investigated by using the X-ray photoelectron spectroscopy (XPS). It was found that the composition ratio of Y to O is 1 to 1.46. Using reflection high energy electron diffraction (RHEED) and glancing angle X-ray diffraction (GXRD), we study the crystallinity of the films. It was noticed that the orientation of deposited film is mainly determined by the substrate temperature and the cluster acceleration energy. We also found that, without acceleration below 800°C, Y 2 O 3 films were grown as polycrystalline. Under the condition of 5 kV acceleration voltage above 650°C, we noticed the heteroepitaxial growth of Y 2 O 3 film on Si(100) substrate. The epitaxial relationship between Y 2 O 3 and Si(100) is presented as Y 2 O 3 (110)//Si(100) and Y 2 O 3 [110]//Si[100] or Y 2 O 3 (110)//Si(100) and Y 2 O 3 [100]//Si[100].

Analysis of the KSTAR Central Solenoid Model Coil Experiment

The Korea Superconducting Tokamak Advanced Research (KSTAR) central solenoid model coil (CSMC) was tested at the National Fusion Research Center (NFRC) to verify the design and manufacturing engineering and to ensure reliable operation. The CSMC reached 8.6 T at 20 kA DC operation successfully. We also assessed the AC loss of the CSMC by means of both a sinusoidal wave with a DC offset as well as a triangular pulse. We derived a friction factor correlation of CSMC at room temperature and at cryogenic temperature (4 ~ 6 K). We also investigated the variation of the friction factor during current charging. The KSTAR PF coil simulation code was validated with inlet and outlet helium temperature, mass flow rate, and pressure drop from the experimental results. The operation temperature margin of the CSVT coil of KSTAR was calculated with the revised KSTAR PF coil simulation code.

Development of CICC for KSTAR TF coil system

The KSTAR (Korea Superconducting Tokamak Advanced Research) superconducting magnet system consists of 16 TFs (Toroidal Field) and 14 PFs (Poloidal Field) coils. Internally-cooled cabled superconductors will be used for the magnet system. The magnet systems adopt a superconducting CICC (Cable-In-Conduit Conductor) type conductor. The KSTAR TF CICC uses Nb/sub 3/Sn superconducting cable with Incoloy 908 conduit. For the fabrication of TF 1/spl sim/3 CICC, cables have been fabricated and the cable has a length of 640 m and a diameter of 22.3 mm. A continuous CICC jacketing system is developed for the CICC jacketing and the jacketing system uses the tube-mill process, which consists of forming, welding, sizing and squaring procedures. The cabling and the jacketing process is described. The welding condition of the Incoloy 908 and design specification of CICCs are also discussed. The fabrication results including the geometrical specification and the void fraction will be discussed.

Development of CICC for KSTAR Superconducting Magnet System

The KSTAR (Korea Superconducting Tokamak Advanced Research) superconducting magnet system adopts a superconducting CICC(Cable-In-Conduit Conductor) type conductor. It consists of 16 TF (Toroidal Field) coils and 14 PF (Poroidal Field) coils and it also uses two different types of CICCs-Nb3Sn cable with Incoloy 908 conduit and NbTi cable with 316LN stainless-steel conduit. A special CICC jacketing system is developed for the KSTAR CICC fabrication: the tube-mill process, which consists of forming, welding, sizing and squaring procedure. The cabling process for TF and PF superconducting cable and the fabrication process of each CICCs (TF CICC and PF CICC) is described. The welding of conduit materials are also discussed. The fabrication results such as the geometrical specification, micro structure and the void fraction will be discussed

High performance pMOSFETs with Ni(Si/sub x/Ge/sub 1-x/)/poly-Si/sub 0.8/Ge/sub 0.2/ gate

For the first time, Ni salicide process is applied directly on poly-Si/sub 0.8/Ge/sub 0.2/ gate, and pMOSFETs utilizing Ni(Si/sub x/Ge/sub 1-x/)/poly-Si/sub 0.8/Ge/sub 0.2/ gate are fully characterized. The excellent value (/spl sim/5/spl Omega///spl square/) of sheet resistance is achieved from 0.15 /spl mu/m Ni(Si/sub x/Ge/sub 1-x/)/Si/sub 0.8/Ge/sub 0.2/ gate, while Co salicide process applied on Si/sub 0.8/Ge/sub 0.2/ gate results in R/sub s/ fail due to Ge segregation. It is also important to note that, with poly-Si/sub 0.8/Ge/sub 0.2/ gate and Ni salicide process, the current drivability of pMOSFETs is significantly improved due to less gate poly depletion and lower source-to-drain resistance (R/sub sd/). Conclusively, Ni salicide is the exclusive process for successful germanosilicide formation on poly-Si/sub 0.8/Ge/sub 0.2/ gate without poly-Si buffer layer and Ni(Si/sub x/Ge/sub 1-x/)/poly-Si/sub 0.8/Ge/sub 0.2/ gate can increase L/sub dsat/ of pMOSFETs by 20% as compared to conventional CoSi/sub 2//poly-Si gate structure.

Induced voltage and alternating current loss in superconducting magnet system for SSTF

The induced voltage in the Samsung Superconducting Test Facility (SSTF) is analyzed according to the calculation of self-inductance and mutual inductance. The voltage induced by blip and compensating coils in the main coils is about 6.4 V. In order to charge the main coils, the power supply must provide the minimum voltage of 1.1 kV. The compensating coils have an influence on the field distribution. The compensating coils result in the decreasing center field about 2.67%. AC losses that include the coupling, hysteresis and eddy losses are calculated in the main, blip and compensating coils. It leads to the temperature rise of about 8 K in main coils.