No. 3 (2007)
Published:
2007-09-30
ARTICLES FROM THIS ISSUE
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Applying shallow nitrogen implantation from rf plasma for dual gate oxide technology
Abstract
The goal of this work was to study nitrogen implantation from plasma with the aim of applying it in dual gate oxide technology and to examine the influence of the rf power of plasma and that of oxidation type. The obtained structures were examined by means of ellipsometry, SIMS and electrical characterization methods.
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Composition and electrical properties of ultra-thin SiOxNy layers formed by rf plasma nitrogen implantation/plasma oxidation processes
Abstract
Experiments presented in this work are a summary of the study that examines the possibility of fabrication of oxynitride layers for Si structures by nitrogen implantation from rf plasma only or nitrogen implantation from rf plasma followed immediately by plasma oxidation process. The obtained layers were characterized by means of: ellipsometry, XPS and ULE-SIMS. The results of electrical characterization of NMOS Al-gate test structures fabricated with the investigated layers used as gate dielectric, are also discussed.
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The influence of annealing (900◦C) of ultra-thin PECVD silicon oxynitride layers
Abstract
This work reports on changes in the properties of ultra-thin PECVD silicon oxynitride layers after high- temperature treatment. Possible changes in the structure, composition and electrophysical properties were investigated by means of spectroscopic ellipsometry, XPS, SIMS and electrical characterization methods (C-V, I-V and charge- pumping). The XPS measurements show that SiOxNy is the dominant phase in the ultra-thin layer and high-temperature annealing results in further increase of the oxynitride phase up to 70% of the whole layer. Despite comparable thickness, SIMS measurement indicates a densification of the annealed layer, because sputtering time is increased. It suggests complex changes of physical and chemical properties of the investigated layers taking place during high-temperature annealing. The C-V curves of annealed layers exhibit less frequency dispersion, their leakage and charge-pumping currents are lower when compared to those of as-deposited layers, proving improvement in the gate structure trapping properties due to the annealing process.
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Comparison of composition of ultra-thin silicon oxynitride layers’ fabricated by PECVD and ultrashallow rf plasma ion implantation
Abstract
In this paper differences in chemical composition of ultra-thin silicon oxynitride layers fabricated in planar rf plasma reactor are studied. The ultra-thin dielectric layers were obtained in the same reactor by two different methods: ultrashallow nitrogen implantation followed by plasma oxidation and plasma enhanced chemical vapour deposition (PECVD). Chemical composition of silicon oxynitride layers was investigated by means of X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). The spectroscopic ellipsometry was used to determine both the thickness and refractive index of the obtained layers. The XPS measurements show considerable differences between the composition of the fabricated layers using each of the above mentioned methods. The SIMS analysis confirms XPS results and indicates differences in nitrogen distribution.
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The role of fluorine-containing ultra-thin layer in controlling boron thermal diffusion into silicon
Abstract
We have investigated the influence of silicon dioxide reactive ion etching (RIE) parameters on the composition of the polymer layer that is formed during this process on top of the etched layer, and finally, the role of this layer in high- temperature thermal diffusion of boron into silicon. The polymeric layer formed on the etched surface appeared to consist of fluorine and silicon fluoride (SiOF and SiF). Concentration of these components changes depending on the parameters of RIE process, i.e., rf power, gas pressure and etching time. The composition of this polymeric layer affects, in turn, boron thermal diffusion into silicon. With increasing rf power, the depth of boron junction is increased, while increasing time of etching process reduces boron diffusion into silicon.
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Oxidation kinetics of silicon strained by silicon germanium
Abstract
This paper reports on the studies of oxidation kinetics of silicon strained by silicon germanium layers. Experimental results of natural, chemical and thermal oxide formation are presented. The oxidation rates of silicon strained by SiGe layers have been compared with the rates of pure Si oxidation. The oxidation kinetics was studied using the parallel model proposed by Beck and Majkusiak. This model was fitted with good result to the obtained experimental data and the parameter that is most probably responsible for the strain effect was identified, as well as its dependence on Ge content in the SiGe layer.
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Influence of the deposition process parameters on electronic properties of BN films obtained by means of RF PACVD
Abstract
This work presents results of investigations of electronic properties of undoped boron nitride (BN) films produced on Si substrates in the course of radio frequency (rf) PACVD process with boron triethyl (C2H5)3B as the boron source. The influence of the deposition process parameters on thickness and electronic properties (resistivity r, dielectric strength EBR) of BN films based on ellipsometry and I-V curve measurements at room temperature is studied. The obtained results show that proper selection of deposition process parameters allows BN layers with the required thickness and advantageous values of r and EBR to be fabricated. BN becomes therefore an interesting material for microelectronics applications.
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Correlation between electric parameters of carbon layers and their capacity for field emission
Abstract
The aim of this work is to study a possibility of field electron emission from carbon layers produced by radio frequency plasma chemical vapor deposition (RF PCVD) method. A correlation between electric parameters of the layers and the ability to produce electron emission is also studied through material (AFM) and electrical (C-V, I-V) characterization of the obtained layers. It is demonstrated that the layers deposited with the highest self-bias exhibit the highest capacity for electron emission.
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Investigations of electron emission from DLC thin films deposited by means of RF PCVD at various self-bias voltages
Abstract
The aim of this paper is to report the results of field emission experiments on undoped, flat diamond-like carbon (DLC) thin films deposited at various self-bias voltages using radio frequency plasma chemical vapor deposition (RF PCVD) technique. It has been observed that the emission properties improve when the absolute value of self-bias voltage becomes higher, e.g., the turn-on field value decreases. The correlation between electron field emission and sp2 content in these films showed improvement of electron emission properties of DLC films for higher amount of sp2 phase.
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Ellipsometric spectroscopy studies of compaction and decompaction of Si-SiO2 systems
Abstract
The influence of the strain on the optical properties of Si-SiO2 system has been investigated by spectroscopic ellipsometry (SE), interferometry and weighing methods. Subtle changes of densification (compaction degree) in silicon dioxide layers on silicon substrates have been determined by weight technique (relying on measurements of the silicon dioxide layer mass and calculations of the volume). Elastic stress in the oxide layers has been measured by Fizeau fringes image analysis method. A comparison is made between the density of the silicon dioxide (r) and the results of calculations made using r = f = (n) relations (where n is the refractive index) given in the literature.
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Investigation of barrier height distributions over the gate area of Al-SiO2-Si structures
Abstract
Distributions of the gate-dielectric EBG(x, y) and semiconductor-dielectric EBS(x, y) barrier height values have been determined using the photoelectric measurement method. Modified Powell-Berglund method was used to measure barrier height values. Modification of this method consisted in using a focused UV light beam of a small diameter d =0.3 mm. It was found that the EBG(x, y) distribution has a characteristic dome-like shape which corresponds with the independently determined shape of the effective contact potential difference fMS(x, y) distribution. On the other hand, the EBS(x, y) distribution is of a random character. It is shown that the EBG(x, y) distribution determines the shape of the fMS(x, y) distribution. The model of the EBG and EBS barrier height distributions over the gate area has been proposed.
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Electrical characterization of ISFETs
Abstract
Methodology of electrical characterization of ISFETs has been described. It is based on a three-stage approach. First, electrical measurements of ISFET-like MOSFETs and extraction of basic parameters of the MOSFET compact model are performed. Next, mapping of the ISFET channel conductances and a number of other characteristic parameters is carried out using a semi-automatic testing setup. Finally, ISFET sensitivity to solution pH is evaluated. The methodology is applied to characterize ISFETs fabricated in the Institute of Electron Technology (IET).
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Charge-pumping characterization of SOI devices fabricated by means of wafer bonding over pre-patterned cavities
Abstract
The quality of the silicon-buried oxide bonded interface of SOI devices created by thin Si film transfer and bonding over pre-patterned cavities, aiming at fabrication of DG and SON MOSFETs, is studied by means of chargepumping (CP) measurements. It is demonstrated that thanks to the chemical activation step, the quality of the bonded interface is remarkably good. Good agreement between values of front-interface threshold voltage determined from CP and I-V measurements is obtained.
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Characterization of SOI MOSFETs by means of charge-pumping
Abstract
This paper presents the results of charge-pumping measurements of SOI MOSFETs. The aim of these measurements is to provide information on the density of interface traps at the front and back Si-SiO2 interface. Three-level charge-pumping is used to obtain energy distribution of interface traps at front-interface
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Charge-pumping characterization of FILOX vertical MOSFETs
Abstract
This paper presents for the first time the results of charge-pumping (CP) measurements of FILOX vertical transistors. The aim of these measurements is to provide information on the density of interface traps at the Si-SiO2 interface fabricated in a non-standard process. Flat-band and threshold voltage, as well as density of interface traps are determined. Good agreement between threshold-voltage values obtained from CP and I-V measurements is observed.
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Arbitrary waveform generator for charge-pumping
Abstract
The paper presents a new signal generator for charge-pumping. Modular structure of the generator is discussed with special emphasis on signal-generation module consisting of five independent signal channels. Digital signal synthesis is chosen to minimize inaccuracies. Noise analysis is performed to demonstrate the validity of the design of signal channel. Calibration procedure is also discussed.
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Electron mobility and drain current in strained-Si MOSFET
Abstract
Electron mobility and drain current in a strained-Si MOSFET have been calculated and compared with the mobility and drain current obtained for the relaxed material. In the first step, our mobility model has been calibrated to the “universal mobility” according to the available experimental data for unstrained Si MOSFETS. Then, employing the mobility parameters derived in the calibration process, electron mobility and the drain current have been calculated for strained-Si MOSFETs.
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Modeling of the inverse base width modulation effect in HBT transistor with graded SiGe base
Abstract
A model of the position of the edge of emitter-base junction in the base and collector current pre-exponential ideality factor in HBT transistor with a SiGe base is presented. The model is valid for transistors with nonuniform profiles of doping and Ge content. The importance of taking into account the dependence of the effective density of states in SiGe on local Ge content and that of electron diffusion coefficient in SiGe on drift field for modeling accuracy is studied.
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Comparison of 4H-SiC and 6H-SiC MOSFET I-V characteristics simulated with Silvaco Atlas and Crosslight Apsys
Abstract
A set of physical models describing silicon carbide with fitting parameters is proposed. The theoretical I-V output and transfer characteristics and parameters of MOS transistors were calculated using Silvaco Atlas and Crosslight Apsys semiconductor device simulation environments
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Monte Carlo method used for a prognosis of selected technological parameters
Abstract
In this paper a smart modeling approach for realistic simulation of selected technological parameters is presented. The technology of making contacts with plasma vapor deposition (PVD) method has been chosen for this purpose. The analysis is based on the Monte Carlo (MC) method and uses the Excel worksheet – the simplest tool, easily accessible to anyone. The statistic parameters are calculated and discussed as we introduce this experiment to demonstrate the advantages of design for six sigma (DFSS)
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The influence of yield model parameters on the probability of defect occurrence
Abstract
This paper describes the analysis of the influence of yield loss model parameters on the calculation of the probability of arising shorts between conducting paths in IC’s. The characterization of the standard cell in AMS 0.8 μm CMOS technology is presented as well as obtained probability results and estimations of yield loss by changing values of model parameters.
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Optical interconnections in future VLSI systems
Abstract
This paper is focused on the latency and power dissipation in clock systems, which should be lower when the optical interconnects are applied. Simulation shows that the power consumed by an optical system is lower than that consumed by an electrical one, however the advantages of optics drastically decrease with the number of output nodes in H-tree. Additionally, simple replacement of an electrical system by an optical clock distribution network (CDN) results in high clock skew, which will be higher than 10% of the clock period for the 32 nm technology node.
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Optimization of an integrated optical crossbar in SOI technology for optical networks on chip
Abstract
In this paper a novel design for an optical network on chip (ONoC), enabling optical on-chip signal routing, is presented. Requirements for such a network are defined and the design of ONoC passive components is described and validated by experimental results.
