Feng-Renn Juang

Comparative Study of Carbon Monoxide Gas Sensing Mechanism for the LTPS MOS Schottky Diodes With Various Metal Oxides

The carbon monoxide (CO) gas sensing mechanism of the Au/MO/n-LTPS MOS Schottky diodes on a glass substrate has been studied with various metal oxides (MO) including SnO2, ZnO, and TiO2 as the sensing element. Because of the deposited SnO2 has the highest band gap and the largest surface to volume ratio morphology, thus leading the Schottky diode with SnO2 to gain the highest relative sensitivity ratio of ~546% to 100 ppm CO ambient under condition of 200°C and -3 V bias. These results are better or comparable to the reported CO sensors. We propose a band gap model to interpret the related sensing mechanism in details.

Improvement of TDDB reliability, characteristics of HfO2 high-k/metal gate MOSFET device with oxygen post deposition annealing

In this work, influences of oxygen effect on an Hf-based high-k gate dielectric were investigated. A post deposition annealing (PDA) including oxygen ion after high-k dielectric deposition was used to improve reliability of the Hf-based high-k/metal gate device. The basic electrical characteristics of devices were compared with and without the PDA process. Experiment results show that the oxygen PDA did not degrade the drive current and effective oxide thickness of the Hf-based gate devices. In addition, reliability issues such as positive bias instability, negative bias instability and TDDB were also improved by the oxygen PDA significantly. During the TDDB test, the charge trapping was characterized by an in situ charge pumping system, which could make us to understand the variations of interface trap during the reliability stress easily.

Effect of Finger Pitch on the Driving Ability of a 40-nm MOSFET With Contact Etch Stop Layer Strain in Multifinger Gated Structure

Effects of the poly gate finger pitch on, hot-carrier-nduced reliability degradation, and radio frequency characteristics of the 40-nm n-channel metal-oxide-semiconductor field-effect transistors with contact-etch-stop-layer (CESL) strain and multifinger gate structures were systematically investigated by both experiment and technology computer-aided design simulation. The finger pitch influences both the transfer of CESL-induced stress into a channel and the shadow effect of a poly gate on a pocket implantation. The results showed that the effects of the poly gate finger pitch were more obvious for pitches less than 0.12 . Additionally, the change in stress on the channel was dominant for pitches larger than 0.12 , but for pitches less than 0.12 , the modulation of pocket implantation shadow effects became the main controlling factor.

N-SiCN/P-Silicon Heterojunction With Porous Silicon Buffer Layer for Low-Cost and High-Temperature Ultraviolet (UV) Detecting Applications

In this paper, we study of n-SiCN/p-PS/p-silicon heterojunction with porous silicon (PS) buffer layer for low-cost and high-temperature ultraviolet (UV) detecting applications in details. The electrochemical anodization and rapid thermal chemical vapor deposition were applied sequentially to form the PS layer and the cubic crystalline n-SiCN film on the top of p-(100) silicon substrate. The PS layer has a high resistivity to suppress the dark current, and provides sponge-like structure to limit strain and cracks development after the post growth cooling. Thus, favors nucleation to result in a better single-crystal SiCN film. Consequently, the developed optical sensing device has a high photo/dark current ratio of 85.4 under room temperature (25degC), with and without irradiation of and 254 nm UV light with 0.5 mW/cm2 optical power. At 200degC the ratio is still equal to 7.42, which are better than the reported ZnO on GaAs substrate or beta-SiC on Si substrate UV detectors without porous treatment.

A Novel Method to Improve Laser Anneal Worsened Negative Bias Temperature Instability in 40-nm CMOS Technology

From the measured data, the impact of the rapid thermal process (RTP) and laser spike anneal (LSA) sequence on negative bias temperature instability (NBTI) and current gain was investigated on 40-nm complementary metal-oxide semiconductor technology. For the conventional sequence RTP/LSA, a significant threshold voltage VT shift is observed due to the NBTI. The thermal gradient in the LSA step induces a thermomechanical stress inducing oxide fixed charges and an increase in Si dangling bonds at the SiON/Si interface, thus increasing the VT shift. By moving the LSA step to before the RTP anneal and coimplanting a carbon atom in the source/drain extension implant processing, the obvious VT shift could be suppressed to the same as the RTP-only anneal. Best of all, the sequence change does not impact the gain of the original combination anneal over the RTP-only anneal in the on current of devices.

The effect of post-hydrogen annealing and multilayer channel structure on nano-crystalline silicon thin film transistor performance

The effect of multilayer channel structure and post-hydrogen annealing (PHA) on the performances of nano-Si thin film transistors (nc-Si TFTs) prepared by a hot wire chemical vapour deposition system on Si substrates was investigated. The experimental results showed that the PHA could improve (about 10%) both saturation and off currents. In particular, when a multilayer channel structure was adopted, the improvement became remarkable, because the underlying layers were used as a buffer layer, which could enhance the films crystalline volume fraction. For example, under the condition of Vgs = 20 V and Vds = 20 V, a TFT with a 4-layer PHA treated nc-Si channel and a 5 nm n+ nc-Si source/drain layer could achieve the highest saturation current Isat of 5.8 × 10−6 A and the lowest Ioff of 4.1 × 10−11 A, respectively. The mechanisms related to the different factors were also discussed in detail.

A Low-Flicker Noise Gate-Controlled Lateral–Vertical Bipolar Junction Transistor Array With 55-nm CMOS Technology

The low-flicker noise (1/f noise) gate-controlled lateral-vertical bipolar junction transistor array (GC-LV-BJTA) is developed with a foundrys 55-nm CMOS technology for low-noise and low-power RF circuit applications. The GC-LV-BJTA is formed by paralleling some unit cells into an array structure for sharing adjacent collectors and bases, thus minimizing the total area. Many efforts, including the use of a deep n-well, a novel layout, an optimized emitter perimeter/area ratio, and a negatively biased gate, have been implemented to suppress the noise level and enhance the current gain. As a result, the GC-LV-BJTA, consisting of 16 unit cells with a 0.16-μm gate length, achieves a high gain of 85.7 with available low 1/f noise level, as compared with the nMOS or SiGe HBT.

The Impact of

The hydrogen detecting performances of Pd/n-LTPS Schottky diodes, with and without a TiO2 interface layer fabricated on glass substrates, were studied in detail. The n-LTPS film, an n-type low-temperature prepared polysilicon film, is formed by annealing an amorphous silicon (a-Si) thin film with excimer laser and treated by PH3 gas plasma. With the TiO2 interface layer, the hydrogen response (Sr) of the n-LTPS Schottky diode under room temperature and -2-V bias is promoted from 331.5% to 3504% in 8000 ppm H2/air ambient, which is comparable to the reported low cost H2 sensor based on bulk Si or III-V compound material. The hydrogen response promotion with the addition of the TiO2 layer is attributed to the suppression of the interface Fermi level pining issue and the increases of hydrogen adsorption activity.

\hbox{TiO}_{2}

Metal organic chemical vapor deposited Gallium nitride (GaN) thin films on (111) n-Si substrate with polycrystalline β-SiC (poly-SiC), cubic β-SiC (c-SiC), and porous β-SiC (PSC) buffer layers were characterized in detail using X-ray diffraction, Fourier transform IR spectroscopy, atomic force microscope, TEM, SEM, and Raman spectrometer. The β-SiC thin film was prepared by rapid thermal chemical vapor deposition, while the PSC thin film was formed by using the electrochemical anodization on a cubic β-SiC thin film. In addition, we used the GaN thin film on different buffer layers to construct a metal-semiconductor-metal (MSM) photodiode and measured its photo/dark current ratio (PDCR) and responsivity with and without the irradiance of an UV light source for examining the ultraviolet detecting properties. Among these MSM photodiodes, the structure of GaN/PSC/n-Si achieved the highest PDCR and responsivity of 6.75 × 105 and 138 mA/W, respectively, for the lowest stress built in the GaN film.

Interface Layer on a Pd/n-LTPS Schottky Diode Hydrogen Detecting Performances

The Pd/n-SnOx/i-diamond/p-diamond diodes prepared by field-enhanced hot-wire CVD (HWCVD) (FEHWCVD) system on a silicon substrate with nanotip structures are studied systematically. Both the nanotip structure and the better film quality deposited by the FEHWCVD lead the developed p-i-n diamond diode to have a high relative sensitivity ratio of ~ 91% to 100-ppm-carbon monoxide (CO)-gas ambient. The sensitivity ratio is better than 79% compared to the one without the nanotip and prepared by the conventional HWCVD. Thus, the developed p-i-n diamond diode has better potential for high-temperature CO sensing applications.