bluuebunny/crossref_metadata_2025_split huggingface dataset:
Silicon Detectors Highly Compensated by Neutron Induced Deep Levels for Low Energy X-RAY Detection
Authors: Li Zheng , Kraner H. W. 
Published: March 2011

ABSTRACTFast neutron radiation damage in silicon results in defect levels which are predominantly acceptor-like at low fluences and may be used to compensate high resistivity ntype material to create very high effective resisitivity material. Compensated material to the order of Neff below 1011/cm3 enables depletion of diode thicknesses ≥ 1mm at reasonable biases (<100V), yielding diodes of reasonable area and capacitance<1 pF which are suitable for low noise applications such as X-ray spectrometry. Although exposure to fluences of this order will greatly increase the generation current and require cooling, most high resolution X-ray spectrometry systems are routinely operated at reduced temperature to achieve low noise operation of the front end electronics. Silicon p+ /n− /n+ implanted devices (area ≤0.25 cm2) made on high resistivity FZ silicon have been irradiated by 1 MeV neutrons to fluences of a few times 1012 n/cm2. Thick n− substrates (d=630 μm and 1000 μm) were used to achieve detector capacitances εεo/d in the range of 1 pF. After a neutron fluence of ϕn=2.9×1012 n/cm2, the total depletion of a p+/n−/n+ detector, 1040 μm thick and an area of 0.1 cm2, is reached at about V=50 Volts, with a Cd of 1 pF and a neutron induced leakage current of about 300 nA at room temperature. A total depletion of an 680 μm thick detector was reached after the fluence of 2-5×1012 n/cm2 at a voltage of 20 volts, and the capacitance of a 0.25 cm2 diode is 4.5 pF The resistivities of the compensated detector substrates are in the range of 100 K Ω-cm, and are not inverted to “p” type. The trapping of collected charge by neutron induced deep levels is modeled and simulated, and is found to be less than a few percent; with no obvious effect on peak shape. Using a resistive feedback preamplifier of modest noise contribution (225 eV), resolution of the Mn K∝ X-ray was 255 eV (FWHM) with 3 μsec shaping time constants. Other effects of uncollected charge will be discussed and comparisons between this type of detectors and Li-drift silicon detectors will be made.
A Robotic Method for Creating Radiation Maps Using Mercuric Iodide Sensor
Authors: Kume Masao , Khosla Pradeep K. 
Published: March 2011

ABSTRACTIn this paper we describe the development of a robotic system that uses Mercuric Iodide (HgI2) sensors to create a map of radiation intensity in the environment. The sensors are mounted at the end-effector of a PUMA 560 manipulator. Data from these sensors is used to compute the radiation intensity. A control system is developed that moves the end-effector along constant intensity contours. The experiments use light sources (instead of radiation sources) and demonstrate the efficacy of such a system to create radiation maps.
M.O.S. Transistors with > 1 μm Thick Gate Oxide for Ionizing Radiation Dosimetry
Authors: Gessinn F. , Sarrabayrouse G. 
Published: March 2011

ABSTRACTThe effects of ionizing radiation on MOS transistors with gate oxide thickness up to 2 μm have been investigated. The major focus of workers in this area has been on the hardening techniques of technologies. On the other side, our goal is to use MOS devices to reach higher sensitivities in order to detect small amounts of dose. Therefore, sensitivity as well as temperature response in the mil-std range and stability of the dosimeters have been studied.
Characteristics of Silicon Photodetector Using Epitaxial Wafer with High Resistivity and Long Recombination Lifetime
Authors: Fujii Yoshimaro , Usami Akira , Kaneko Keisuke , Wada Takao 
Published: March 2011

ABSTRACTFor the high quality Si Photodetector, the high resistivity epitaxial wafer using the low resistivity substrate were studied. The buffer layer was introduced in the interface, and it was very effective on the crystal quality of the epitaxial layer. Recombination lifetime in the epitaxial layer became very uniform and long even in the interface region which was confirmed by measuring the lifetime depth profiles. Then Si PIN Photodiode was fabricated on the above high quality epitaxial wafer and its optoelectric characteristics was evaluated.
Microscopic Noncontact Electrical Evaluation for the Silicon-on-Insulator Layer with Voids
Authors: Usami A. , Nakai T. , Ishigami S. , Wada T. , Matsuki K. , Takeuchi T. 
Published: March 2011

ABSTRACTWe evaluate the electrical properties of the silicon-on-insulator (SOI) layer made by the wafer bonding using a noncontact laser beam induced conductivity/current (LBIC) method. Since the thickness of the SOl layer used in this study is about 40μm, the He-Ne laser, whose penetration depth for Si is small (about 3μm), is used as the carrier-injection light source.We use the SOI wafer with some voids which are revealed by the X-ray topography. We have reported that the LBIC signal intensity decreases in the void region. In this study, we measure the microscopic signal variation near the edge of the void. It is observed that the LBIC signal intensity decreases in the outside region within a distance of about 700μm from the void edge. The diffusion length of the injected carrier (100-150μm) is shorter than the width of the region where the signal intensity decreases. Thus the decrease is not due to the carrier diffusion to the void. These results show that the formation of the void degrades the electrical properties not only in the void region but also outside the void.
Effects of Electron Radiation on the Optical Constants of P-Type Silicon
Authors: Russo Onofrio L. , Dumas Katherine A. 
Published: March 2011

ABSTRACTThe optical constants n and k are determined for p-type silicon at the Eo and El and critical point energies for one MeV electron irradiated samples. The value for fluences of 1014 and 1016 e−/cm2 are compared to samples before irradiation. The real, ε1 and imaginary,ε2 components of the dielectric function, ε, used to find n and k, were obtained by measurement of tanψ and δ using spectroscopic ellipsometry (SE). The data show that changes in δ, in particular, are greater in the region about Eo than of E1. This is consistent with electrolyte electroreflectance (EER) results in which the Lorentz line shape is narrower for Eo than for E1. The value of n is found to increase and k to decrease with e- radiation at the critical points, although, neither does so monotonically. The change in n at the Eo critical point is greater than at the higher energy main structure E1 whereas, k is a slower varying function in this region.
X-Ray Fluorescence Analysis Capability of HGI2 Detector Systems
Authors: Wang Y.J. , IWANCZYK J.S. 
Published: March 2011

ABSTRACTA laboratory XRF analysis system employing an HgI2 spectrometer detector has been built. The system consists of an x-ray generator tube, a rotating carousel holding multiple XRF targets, and a probe head containing the HgI2 detector. Tests have been performed on several samples, under vacuum, helium and nitrogen ambient atmospheric conditions. This is of particular interest, since the applications for such an XRF system include operation under different ambient conditions. For applications in terrestrial and space planetary exploration, the expected temperatures and gas ambient will vary widely. Comparative analyses using the various gases were made on spectra obtained from standard geological samples.
Electrical and Physical Characterization of Tin Diffusion Barrier for Sub-Micron Contact Structure
Authors: Yao G.D. , Lu Y.C. , Prasad S. , Hata W. , Chen F.S. , Zhang H. 
Published: March 2011

ABSTRACTTiN diffusion barriers have been widely used in submicron contact structures, due to its good adhesion (to SiO2, W, Al and Si) properties, low diffusivity (for Si, W and Al) and compatibility with TiSi2 processing. The purpose of this paper is to present the results of physical and electrical characterization of contact structures with a TiN barrier and W plugs. Two different barrier metal processes were compared, Viz: sputtered Ti followed by post RTN and Ti/TiN films followed by post RTA in the range of 600° to 800°C. The devices were thermal stressed at 450°C for 7 hrs after W plug formation and Al metallization. Ti/TiN films with post RTA are generally superior barrier layers than Ti films with post RTA as shown by electrical characterization of contact resistance and barrier integrity. The relationship between electrical properties and microstructure for the two different barrier structures is discussed. W/TiN and TiN/TiSi2 interface structures were characterized using high resolution TEM. TiSi2 was found to be epitaxially grown during RTA, under certain process conditions. The crystal structure of TiSi2 was determined from electron diffraction patterns.
Temperature Measurement for Rtp
Authors: Brueck S. R. J. , Zaidi Saleem H. , Lang M. K. 
Published: March 2011

ABSTRACTA non-contact temperature measurement technique based on diffraction-analysis monitoring of the thermal expansion of materials is discussed. Due to the need for noncontact temperature measurements during semiconductor processing, silicon was chosen for this demonstration. The diffraction method requires a grating of suitable spatial frequency etched on the surface of the silicon wafer. The diffraction angle from the grating depends on the grating period which varies with temperature. Two symmetrically disposed incident beams are used to provide a differential measurement which is relatively independent of sample tilt. A computer system is used to monitor the diffraction order movement, from the order separation a relative temperature change can be calculated in near real-time. Temperature sensitivity for the diffraction technique is inversely dependent on the grating length (number of lines) and independent of the grating width. A sensitivity of 0.75°C is demonstrated for a 3-mm wide grating over a 20-700°C temperature range.
Application of Constant Absorptivity Ring (Car) to Improve Polysilicon Thickness Uniformity In A Rapid Thermal Chemical Vapor Deposition Reactor
Authors: Sanganeria Mahesh K. , ÖztÖrk Mehmet C. 
Published: March 2011

ABSTRACTRapid Thermal Chemical Vapor Deposition (RTCVD) is a promising technology for thin film deposition in advanced cluster tool systems. It is well known that, if left uncompensated, excessive heat losses that occur around the wafer edge can lead to temperature and deposition non-uniformities. Using polysilicon deposition on SiO2 as an example we have shown that deposition non-uniformity can be aggravated by absorptivity variations across the wafer. In this paper, we propose a novel approach to alleviate this problem. In this technique, the edge cooling effect is compensated by increasing the absorptivity of the substrate around its perimeter. This is achieved by etching a thin (width≈200μm) ring from the isolation oxide around the wafer perimeter prior to polysilicon deposition. During polysilicon deposition, the absorptivity of the silicon-oxide-polysilicon structure continually changes resulting in positive and negative feedback mechanisms in certain polysilicon thickness ranges determined by both modeling and experiments. However, this absorptivity always remains less than the constant absorptivity of the silicon-polysilicon ring along the perimeter which is referred to here as the Constant Absorptivity Ring (CAR). The higher absorptivity of CAR shields edge cooling effects from the rest of the wafer. In this paper, we present the results of our experiments conducted to demonstrate the effectiveness of CAR in improving uniformity of polysilicon. We show that by using CAR uniform films can be obtained in a reactor which otherwise delivers a polysilicon non-uniformity of 30-40%.
Microscale Radiation Effects in Multilayer Thin-Film Structures During Rapid Thermal Processing
Authors: Wong Peter Y. , Hess Christopher K. , Miaoulis Ioannis N. 
Published: March 2011

ABSTRACTThe individual film thicknesses of multilayered structures processed by rapid thermal processing are of the same order as the wavelengths of the incident radiation. This induces optical interference effects which are responsible for the strong dependency of surface reflectivity, emissivity, and temperature distributions on the geometry of the layering structures, presence of patterns, and thickness of the films. A two-dimensional, finitedifference numerical model has been developed to investigate this microscale radiation phenomena and identify the critical processing parameters which affect rapid thermal processing of multilayer thin films. The uniformity of temperature distributions throughout the wafer during rapid thermal processing is directly affected by incident heater configurations, ramping conditions, wafer-edge effects, and thin-film layering structure. Results from the numerical model for various film structures are presented for chemical vapor deposition of polycrystalline silicon over oxide films on substrate. A novel technique using an edge-enhanced wafer which has a different film structure near its edge is presented as a control over the transient temperature distribution.
High Quality Silicon Epitaxy In An Ultra High Vacuum Rapid Thermal Cvd Reactor: An Application to Single Wafer Processing
Authors: Sanganeria Mahesh K. , Violetite Katherine E. , ÖztÜrk Mehmet C. 
Published: March 2011

ABSTRACTIn this paper, we report epitaxial growth of silicon in an ultra high vacuum rapid thermal chemical vapor deposition (UHV/RTCVD) equipment. In this study, our objectives were low temperature/low thermal budget processing and a high throughput compatible with single wafer manufacturing. The reactor consists of a load lock, a main process chamber and an intermediate cryopumped vacuum buffer chamber between the two chambers. An ultra-clean process environment was achieved using oil free pumps and point of use gas purifiers. The wafer is heated by a Peak Systems LXU-35 arc lamp through a quartz window. In this system, we achieved good quality silicon epitaxy at low temperature (T≤800°C) in the very low, 100 mTorr, pressure regime with high throughput (Growth rate>0.25 μm/min.). High growth rate was achieved using Si2H6 as the reactant gas instead of SiH4 or SiH2C12 which are more commonly used gases for epitaxial growth. High temperature in-situ cleaning was completely eliminated by initiating film growth on a hydrogen passivated surface obtained via dilute HF etching. Generation lifetimes in the 200-400μs range were measured for deposition temperatures of 700°C, 750°C and 800°C with no strong dependence on the deposition temperature.
Modeling of Boron Diffusion and Activation for Nonequilibrium Rapid Thermal Annealing Application
Authors: Kinoshita H. , Huang T. H. , Kwong D. L. 
Published: March 2011

ABSTRACTThe diffusion and activation of ion implanted boron and BF2 during rapid thermal annealing (RTA) was modeled by considering the reaction kinetics between point defects and boron. The diffusion model uses the Monte Carlo generated point defect profiles, an extended defect model and a surface amorphization model for high dose BF2 implantation. Excellent simulation results have been achieved by using a single set of diffusion and kinetic parameters to model the enhanced diffusion of boron during RTA for a wide range of B and BF2 implant doses.
In-Situ Processing of Si Film Structures in a Rapid Thermal Chemical Vapor Deposition Reactor
Authors: Green M. L. , Brasen D. , Luftman H. , Boone T. , Krisch K. 
Published: March 2011

ABSTRACTAlthough the benefits of in-situ processing seem intuitively obvious as higher yield due to particle and contamination control, there is presently little data to support these claims. However, materials characterization data on in-situ grown films suggest that it will be advantageous. In this paper we explore the advantages of in-situ processing in a load-locked rapid thermal chemical vapor deposition (RTCVD) chamber for such processes as cleaning, epitaxial growth, oxidation and polysilicon growth. The cold wall nature and low thermal mass of the RTCVD chamber make it an ideal candidate for a cluster module for thermal processing in an integrated process tool.
A Dual-Function Uhv-Compatible Chamber for i) Low-Temperature Plasma-Assisted Oxidation, and ii) High-Temperature Rapid Thermal Processing of Si-Based Dielectric Gate Heterostructures
Authors: Hattangady S. , Xu X-L , Watkins M.J. , Hornung B. , Misra V. , Lucovsky G. , Wortman J.J. 
Published: March 2011

ABSTRACTA combination of i) low-temperature, 300-400°C, plasma-assisted oxidation to form the SiO2/Si interfaces, and ii) 800°C rapid thermal chemical vapor deposition, RTCVD, to deposit SiO2 thin films have been used to fabricate gate-oxide heterostructures. This sequence separates SiO2/Si interface formation by the oxidation process from the deposition of the bulk oxide layer by RTCVD. These two processes were performed in situ and sequentially in a single-chamber, ultraclean quartz reactor system. We have studied the chemistry of the interface formation process by Auger electron spectroscopy, AES, and the electrical properties of MOS devices with Al electrodes by C-V techniques.
Simultaneous Formation of Front and Back Contacts on Solar Cells Using Optical Processing
Authors: Sopori Bhushan L. 
Published: March 2011

ABSTRACTA new approach for semiconductor processing is described in which a melt is created at a semiconductor-metal (S-M) interface by shining light of a suitable spectrum from the semiconductor side. The melt can be controlled and confined to a thin region in the vicinity of the interface by controlling the energy delivered to the interface. The interface region regrows epitaxially on silicon as a Si-metal alloy. This phenomenon appears to be an optically induced effect. The interface reaction is greatly diminished if the light is incident from the metal side. This effect is applied to form low resistivity contacts to N+/ P type solar cells in a one-step process.
A Novel Implantation Free Raised Source/Drain Mosfet Process Using Selective Rapid Thermal Chemical Vapor Deposition Of In-Situ Boron Doped SixGe1-x
Authors: Ren Xiaowei , Öztürk Mehmet C. , Grider Douglas T. , Sanganeria Mahesh , Ashburn Stanton 
Published: March 2011

ABSTRACTIn this paper, we report electrical characterization of raised source/drain MOS transistors fabricated using selectively deposited, in-situ boron doped SixGe1-x as a solid diffusion source to form the source/drain junctions. The alloy can be deposited with an enhanced selectivity at temperatures as low as 600°C resulting in an abrupt doping profile at the SixGe1-x/Si interface. After deposition, junctions are formed by diffusion of boron from the deposited layer into the silicon substrate. The selectively deposited alloy can serve as a sacrificial layer for self-aligned silicide formation elimintaing the problem of silicon consumption in the substrate. In this work, selective depositions were performed in a typical cold-walled, lamp heated rapid thermal chemical vapor deposition (RTCVD) system at ∼ 610 °C using SiH2C12, GeH4 and B2H6 as the reactive gases. Using this process, MOS transistors with effective channel lengths down to 0.45 gtm were successfully fabricated.
A Robust LPCVD Nitride Integrated Process for High Density Non-Volatile Eprom Memories
Authors: Sethi R. B. , Ciari R. P. , Anderson L. , Kim U. S. , Bergemont A. 
Published: March 2011

ABSTRACTA robust 6" hotwall flatzone nitride system is developed for scaled ONO interpoly. dielectric application in a high density EPROM memory cell. This system is designed to operate at low temperature (660° C) and gas ratio (4:1 NH3: DCS) with integrated silicon carbide components. The obtained key features are low defects (0.25 #/cm2 particles), smooth topography (measured by atomic force microscopy) and superior electrical interface as measured by electrical and optical methods.
A Large Area Rapid Thermal Processor for Flat Panel Displays
Authors: Lee Chunghsin , Bramhall Robert B. 
Published: March 2011

ABSTRACTThe advantages of rapid thermal processing over slow, batch type processing have been demonstrated clearly in flat panel display manufacturing for a number of years. In the case of electroluminescence FPD, the brightness of the blue phosphor is increased by as much as 100%.However, rapid thermal processors that use a lamp-based heat source - either a tungsten lamp array or a single arc lamp - have great difficulty in achieving heating uniformity over large areas.By using a resistance-heated continuous heat source developed initially for RTP processing of large silicon wafers, temperature uniformity of less than +/− 2.5°C has been achieved over a panel with diagonal of 530mm.A description of the system and its characteristics are presented.
Thin Oxynitride Films Prepared by Low Pressure Rapid Thermal Chemical Vapor Deposition
Authors: Mclarty P.K. , Hill W.L. , Xu X.L , Wortman J.J. , Harris G.S. 
Published: March 2011

ABSTRACTThin silicon oxynitride (Si-O-N) films have been deposited using low pressure rapid thermal chemical vapor deposition (RTCVD) with silane (SiH4), nitrous oxide (N2O), and ammonia (NH3) as the reactive gases. Structural analysis coupled with a study of deposition conditions indicate that an increase in NH3/N2O flow rate ratios leads to an increased N/O atomic ratio and a decreased Si-O-N deposition rate. Thin film (55-75A) polySi/Si-N-O/Si capacitors and transistors were fabricated for NH3/N2O flow rate ratios from 20% to 100%. Some of the films were subjected to a post deposition anneal at 950°C for 15 seconds in both argon and oxygen. Capacitance voltage measurements indicate a mid-gap interface trap density of ≤ 6 × 1010 eV−1cm−2 for all the films independent of both nitrogen content and post deposition annealing conditions. The transconductance was studied as a function of NH3/N2O flow rate ratio and decreasing peak gm values but improved high field degradation was observed for increased nitrogen content. This is consistent with previous work on nitrided oxides and suggests that the films are under tensile stress. Hot carrier stress at maximum substrate current was performed with the Si-O-N films displaying larger threshold voltage shifts when compared to furnace SiO2 indicating the possible existence of hydrogen related traps.
Characterization of Oxygen-Doped and Non-Oxygen-Doped Polysilicon Films Prepared by Rapid Thermal Chemical Vapor Deposition
Authors: Xu Xiaoli , Misra Veena , Harris Gari S. , Spanos Lycourgos , Öztiirk Mehmet C. , Wortman Jimmie J. , Maher Dennis M. , Irene Eugene A. 
Published: March 2011

ABSTRACTPolySi films deposited with and without oxygen doping using rapid thermal chemical vapor deposition (RTCVD) have been investigated. Experimental results show that RTCVD systems can be used to provide high deposition rates ( 900-1000 Å/min at 700 °C) for both oxygen-doped and non-oxygen-doped polySi films. The surface roughness of the RTCVD polySi film is about half that of conventional LPCVD polySi films. The surface roughness and grain size of the RTCVD polySi film can be further reduced using oxygen doping. The catastrophic breakdown strength for capacitors using oxygen-doped polySi electrodes are improved compared with the breakdown strength for capacitors using non-oxygen-doped polySi electrodes. Electrical resistivities of B, P and As doped samples of polySi films with oxygen doping are found to be larger than those of polySi films without oxygen doping. Resistivities of silicides formed on the oxygen-doped polySi samples are approximately the same for those of silicides formed on non-oxygen-doped polySi samples.