Leakage Current Of Transistors Research Articles

CHARACTERISATION OF NARROW-SPACED ISOLATION IN A TWIN RETROGRADE WELL SUBMICRON CMOS PROCESS

Small N+-P+ spacings have been realised using twin retrograde well technology in combination with an advanced isolation scheme. In this paper suppression of field transistor leakage currents is demonstrated by simulation and experimental results. The results show that an N+-P+ spacing of 2.5 ?m can be realised without increased narrow-width effects in adjacent transistors.

The effect of 1300-1380 degrees C anneal temperatures and material contamination on the characteristics of CMOS/SIMOX devices

The characteristics of CMOS transistors fabrication on silicon implanted with oxygen (SIMOX) materials were measured as a function of the silicon superficial layer contamination levels. In addition, postimplant anneal temperatures of 1300 degrees C, 1350 degrees C, and 1380 degrees C were examined. It is found that the transistor leakage currents as well as the integrity of the gate oxide and implanted SIMOX oxide are functions of the carbon content in the starting material. Leakage currents below 1.0*10/sup -12/ A/ mu m of channel width have been measured when the carbon concentration is reduced to 2*10/sup 18//cm/sup 2/. In addition, the integrity of the transistor gate dielectric, SIMOX implanted oxide, and oxygen precipitate density are seen to be a function of the postimplant anneal temperature. A gate dielectric breakdown field of 10 MV/cm has been achieved when the postimplant temperature is increased to 1380 degrees C. >

Effects of fluorine ion implantation on metal-oxide-semiconductor devices of silicon-on-sapphire

Effects of fluorine ion implantation on electrical characteristics of metal-oxide-semiconductor (MOS) devices on silicon-on-sapphire have been investigated. The fluorine implantation generates deep acceptor levels, the nature of which is significantly affected by the sequence of the implantation and gate oxidation in device fabrication process steps. It was found that drain leakage current of fluorine-implanted MOS transistors can be reduced to about 0.1 times compared with unimplanted devices without degrading the basic electrical characteristics.

Lateral Seeding of Silicon-On-Insulator Using an Elliptical Laser Beam: A Comparison of Scanning Methods

ABSTRACTTwo scanning methods for laterally-seeded recrystallization of striped silicon-on-insulator/seed structures with an elliptical laser beam are discussed. One method requires repeated remelting of the silicon film and is controlled by the temperature of the substrate, which is locally heated by the beam. This method results in very few defects and single-crystal silicon-on-insulator stripes up to 50 μm wide. The second method involves little remelting and is primarily controlled by the lateral offset of the beam with respect to the stripes. Single-crystal silicon-on-insulator stripes up to 40 μm wide have been obtained, with defects consisting primarily of stacking faults and twins, as well as some grain boundaries. These defects show little effect on MOS transistor leakage current.

Dc leakage currents in trichloroethylene oxides

Undoped silicon dioxide is compared to oxide in which trichloroethylene (TCE) was used during growth. The gate leakage currents in MOS transistors are examined. It is shown that a reduction in the leakage current occurs in TCE oxides. A novel measurement technique is employed to examine the gate leakage currents of the MOSFETs.

The influence of boron induced and oxidation induced defects on bipolar transistor slice yield

Silicon lattice defects induced by high concentration boron diffusion, or by oxidation, are a major cause of high leakage currents in bipolar transistors. The incidence of such defects in narrow base, high frequency, transistors is investigated using Sirtl etch and the transmission electron microscope, and related to the transistor leakage currents. Boron induced defects are found to cause high emitter-base leakage, but it is shown that their density may be reduced by a nitric acid boron glass strip prior to base drive. A particular type of oxidation induced defect is found to cause high collector-emitter leakage, and appearance of this defect is correlated with silicon material batch. As an example, yields of slices of the British Telecom 40 Type submarine cable transistor meeting a specification including low leakage currents, are shown to be related closely to the silicon material/boron glass strip combination used.

Subthreshold drain leakage currents in MOS field-effect transistors

There are two contributions to the drain-source leakage current in MOS field-effect transistors for gate voltages below the extrapolated threshold voltage (V tx ) : 1) reverse-bias drain junction leakage current, and 2) a surface channel current that flows when the surface is weakly inverted. Nearly six orders of magnitude of drain-source current from the background limit imposed by the drain junction leakage to the lower limits of detection of most curve tracers (0.05 µA) are controlled by gate-source voltages below the extrapolated threshold voltage. It is shown that this current flows only for gate voltages above the intrinsic voltage V i , the gate voltage at which the silicon surface becomes intrinsic. For gate voltages between V i and V tx the surface is weakly inverted with the resulting channel conductivity being responsible for the drain-source current tails observed for gate voltages below V tx . The importance of the intrinsic voltage in designing low-leakage CMOS and standard PMOS circuitry is discussed.

Noise in solid-state devices and lasers

A survey is given of the most important noise problems in solid-state devices. Section II discusses shot noise in metal-semiconductor diodes, p-n junctions, and transistors at low injection; noise due to recombination and generation in the junction space-charge region; high-level injection effects; noise in photodiodes, avalanche diodes, and diode particle detectors, and shot noise in the leakage currents in field-effect transistors (FETs). Section III discusses thermal noise and induced gate noise in FETs; generation-recombination noise in FETs and transistors at low temperatures; noise due to recombination centers in the space-charge region(s) of FETs, and noise in space-charge-limited solid-state diodes. Section IV attempts to give a unified account of 1/f noise in solid-state devices in terms of the fluctuating occupancy of traps in the surface oxide; discusses the kinetics of these traps; applies this to flicker noise in junction diodes, transistors, and FETs, and briefly discusses flicker noise in Gunn diodes and burst noise in junction diodes and transistors. Section V discusses shot noise in the light emission of luminescent diodes and lasers, and noise in optical heterodyning. Section VI discusses circuit applications. It deals with the noise figure of negative conductance amplifiers (tunnel diodes and parametric amplifiers), and of FET, transistor, and mixer circuits. In the latter discussion capacitive up-converters, and diode, FET, and transistor mixers are dealt with.

Effect of gold on surface properties and leakage current of MOS transistors

The effect of gold on the characteristics of some experimental n-channel MOS transistors is investigated. It is shown that gold can produce positive charges at the oxide-silicon interface and therefore can change a device made on p-type substrate from depletion type to enhancement type. MOS transistors have been made on oxygen doped and oxygen-free materials and it is shown that gold has the same effect on their surfaces, but the opposite effect on the leakage current which is independent of the applied negative gate voltage. It is shown that gold can eliminate the leakage current if the silicon is doped with oxygen, because the SiO 2 clusters, which are formed at dislocations in the space between the diodes, have similar properties to oxides grown on the surface of the silicon. Devices have also been made on (111) and (110) planes and it is shown that in practice the (110) plane can produce a lower density of negative charge at the oxide-silicon interface, and that crystallographically it is a better plane in terms of dislocation orientation for MOS transistors.

In-Circuit Transistor Leakage Current Testing

An instrument capable of measuring leakage current of transistors while the trarisistor remains in the circuit was developed. This instrument gives an accurate leakage current measurement in a large variety of circuits as well as being simple to operate, lightweight, battery powered, and portable for use in the field. This was accomplished by the measurement of the transistor leakage current ICBX, which is the collector current when both the collector and emitter junctions of the transistor are reverse biased. This particular leakage current was chosen because it is nearly independent of the gain parameters of the transistor and a very close approximation to the fundamental leakage current ICBO. The present instrument measures leakage currents as low as 1 µa with a collector load resistance down to 500 Ω. At present, an accurate instrument is not commercially available for measuring transistor leakage current in the circuit. The results presented in this paper indicate a method for adding the capability of measuring in-circuit transistor leakage current to future transistor testers.