Dong Shurong

Optical and electrical properties of N-doped ZnO and fabrication of thin-film transistors

Using NH3 as nitrogen source gas, N-doped ZnO (ZnO:N) thin films in c-axis orientation were deposited on glass substrates by radio frequency magnetron sputtering at room temperature. The ZnO:N thin films display significant increase of resistivity and decrease of photoluminescence intensity. As-grown ZnO:N material was used as active channel layer and Si3N4 was used as gate insulator to fabricate thin-film transistor. The fabricated devices on glasses demonstrate typical field effect transistor characteristics.

An improved GGNMOS triggered SCR for high holding voltage ESD protection applications

Developing an electrostatic discharge (ESD) protection device with a better latch-up immunity has been a challenging issue for the nanometer complementary metal-oxide semiconductor (CMOS) technology. In this work, an improved grounded-gate N-channel metal-oxide semiconductor (GGNMOS) transistor triggered silicon-controlled rectifier (SCR) structure, named GGSCR, is proposed for high holding voltage ESD protection applications. The GGSCR demonstrates a double snapback behavior as a result of progressive trigger-on of the GGNMOS and SCR. The double snapback makes the holding voltage increase from 3.43 V to 6.25 V as compared with the conventional low-voltage SCR. The TCAD simulations are carried out to verify the modes of operation of the device.

Investigation of the trigger voltage walk-in effect in LDMOS for high-voltage ESD protection

The trigger voltage walk-in effect has been investigated by designing two different laterally diffused metal—oxide—semiconductor (LDMOS) transistors with an embedded silicon controlled rectifier (SCR). By inserting a P+ implant region along the outer and the inner boundary of the N+ region at the drain side of a conventional LDMOS transistor, we fabricate the LDMOS-SCR and the SCR-LDMOS devices with a different triggering order in a 0.5 μm bipolar-CMOS-DMOS process, respectively. First, we perform transmission line pulse (TLP) and DC-voltage degradation tests on the LDMOS-SCR. Results show that the trigger voltage walk-in effect can be attributed to the gate oxide trap generation and charge trapping. Then, we perform TLP tests on the SCR-LDMOS. Results indicate that the trigger voltage walk-in effect is remarkably reduced. In the SCR-LDMOS, the embedded SCR is triggered earlier than the LDMOS, and the ESD current is mainly discharged by the parasitic SCR structure. The electric potential between the drain and the gate decreases significantly after snapback, leading to decreased impact ionization rates and thus reduced trap generation and charge trapping. Finally, the above explanation of the different trigger voltage walk-in behavior in LDMOS-SCR and SCR-LDMOS devices is confirmed by TCAD simulation.

Modelling and Optimization for Deposition of SiOxNy Films by Radio-Frequency Reactive Sputtering

SiOxNy films are deposited by reactive sputtering from a Si target in Ar/O2/N2 atmospheres. In order to achieve the control of film composition and to keep a high deposition rate at the same time, a new sputtering model based on Bergs work is provided for the condition of double reactive gases. Analysis based on this model shows that the deposition process can easily enter the target-poisoning mode when the preset gas flow (N2 in this work) is too high, and the film composition will change from nitrogen-rich to SiO2-like with the increase of oxygen supply while keeping the N2 supply constant. The modelling results are confirmed in the deposition process of SiOxNy. Target self-bias voltages during sputtering are measured to characterize the different sputtering modes. FTIR-spectra and dielectric measurements are used to testify the model prediction of composition. Finally, an optimized sputtering condition is selected with the O2/N2 flow ratio varying from 0 to 1 and N2 supply fixed at 1 sccm. Average deposition rate of 17 nm/min is obtained under this selected condition, which has suggested the model validity and potential for industry applications.

A new low-emissivity films Prepared by Magnetron Sputtering

Low-emissivity (Low-E) films, which have low transparence in near infrared region, are prepared by RF magnetron reactive sputtering and DC sputtering in turn as the structure of air/TiO2/Ti/Ag/TiO2/ on the glass. Titanium layer protection Ag layer from being oxidized is observed. The transmittance of low-E films was measured by spectrophotometer. The Low-E films can get a best transmittance, while the thickness of titanium layer is about 1 nanometer. In the visible region (380 nm - 780 nm), the highest transmittance is up to 82.4%, and the average transmittance is 75%. In the near infrared region (780 nm - 2500 nm), the average transmittance is 16.2%.

Studies of BaO-Nd2O3-TiO3 thin films by RF Sputter and its TMLs

As a high permittivity and low loss ceramic, BaO-Nd2O3-TiO3 (BNT) is widely used in millimeter wave dielectric resonator. Perfect BNT thin films are obtained by through high density plasma RF sputter, and compared dielectric properties with bulk. The results show that underlay temperature has mainly effect on thin films. The optimize technology is gotten. Through simulation, thin film microstrip line based on BNT has more high integration and more excellent microwave dielectric loss properties than standard microstrip Line.

Design of dielectrically-loaded printed quadrifilar helical antenna for GPS applications

A quadrifilar antenna for GPS applications is designed by HFSS. This quadrifilar antenna has four helical arms wound around a dielectric cylinder which has high permittivity and low loss. The four arms are fed with equal amplitudes with 0deg, 90deg, 180deg, 270deg phase by integrated feeding network. Through precisely control of phase and design of high permittivity ceramic, quadrifilar antenna obtains proper resonant frequency and good radiation pattern. The effects including resonant frequency, axial ratio, radial pattern, impedance, gain, efficiency are simulated.

Active feedback control of reactive sputtering AlN thin film fro FBAR

AlN thin films with high c-axis orientation are deposited by DC reactive magnetron sputtering and active feedback control system. Based on the analysis of the Berg hysteresis model, the authors analyze the technology parameter influence on the hysteresis effect, including pumping speed, temperature of substrate and target, input power, target to substrate distance and area of target. A new active feedback control method and some improvement to eliminate hysteresis effect are presented to quickly depositing AlN thin film with high c-axis oriented