Study on curing reaction of 4-aminophenoxyphthalonitrile/bisphthalonitrile

A series of phthalonitrile blending resins were prepared from 4-aminophenoxyphthalonitrile(APN) and 4,4'-bis(3,4- dicyanophenoxy)biphenyl(BPH) by directly powder-mixing and copolymerization.Differential scanning calorimeter(DSC) and dynamic rheology were used to study the curing reaction behaviors of APN/BPH blends,and the results indicated that the introduction of APN accelerated the curing rate of BPH,and the existence of BPH decreased the curing temperature of APN/BPH systems.The thermal stability of postcured APN/BPH resins was investigated by thermogravimetric analysis(TGA),and the TGA results indicated that the crosslinked polymers of APN/BPH systems possessed good thermal stability.

Preparation of the Bilayer Film Electret of SiO_(2)Matrix Amorphous Composite

Through the fusing and the thermal oxidation technology, the bilayer compound film (SiO_(2)-PbO-Al_(2)O_(3))/SiO_(2) electret was successfully prepared on the single crystalline silicon substrate. Experiments indicated that this co-mixture laminated-layer compound film possessed unique excellent electret properties. Without any chemical modification, the surface electric potential of the sample could get the equal value of the grid voltage after corona charging and decayed no more than 5% in 270d. Moreover, not only did the samples have the excellent capability of negative charges injection and storage, but also did they have the outstanding positive ones. Thermally stimulated discharge current spectra showed that the compound film had unique, single but stable charge-trapped mechanism corresponding to T = 290℃ positive/negative discharge current peak, which could be attributed to its special inner microstructure.

Preparation of AlN Films by Ion-Beam-Enhanced Deposition

Aluminium nitride (AIN) films have been synthesized on Si(l00) substrates by ion-beam-enhanced deposition. The spreading resistance profile results suggest that the spreading resistance decreases with increasing rates of Al evaporation. If the evaporation rate of Al is higher than 2.5 A/s, the quality of the AIN film will greatly deteriorate. The spreading resistance of the best quality film deposited at 0.5 A/s rate of Al was larger than 108Ω. X-ray photoelectron spectroscopy measurements indicate the formation of AIN films at 0.5 and 1.0 A/s evaporation rates of Al. With the increasing evaporation rate of Al, the ratio of N to Al is decreased. When deposited at 0.5 and 1.0A/s evaporation rates of Al, the ratios of N to Al were 0.402:1 and 0.250:1, respectively. Atomic force microscopy observation also shows that the surfa:e of the AIN film formed at the 0.5 A/s rate is smoother and more uniform than that formed at 1.0 A/s.

Multimode-Waveguide-Based Optical Power Splitters in Glass

Low-loss glass-based buried multimode waveguides are fabricated by using the field-assisted Ag＋-Na＋ ionexchange technique, and multimode optical power splitters are investigated. The measured loss of the multimode waveguides is lower than 0.1 dB/cm, and the additional loss of the multimode optical power splitters is lower than 1.3 dB under the uniform splitting condition.

DEEP LEVEL DEFECTS IN SI-IMPLANTED LEC UNDOPED Si-GaAs

The residual electrically active defects in(4×1012cm-2（30KeV）+5×1012cm-2（130KeV）)si-implanted LEC undoped si-GaAs activated by two-step rapid thermal annealing（RTA）LABELED AS 970℃（9S）+750℃（12S）have been investigated with deep level transient spec-troscopy（DLTS）.Two electron traps ET1(Ec-0.53eV,σn=2.3×10-16cm2)and ET2（Ec-0.81eV,σn=9.7×10（-13）cm2）are detected.Furthermore,the noticeable variations of trap’s con-centration and energy level in the forbidden gap with the depth profile of defects induced by ion im-plantation and RTA process have also been observed.The[Asi·VAs·AsGa]and[VAs·Asi·VGa·AsGa]are proposed to be the possible atomic configurations of ET1 and ET2,respectively to explaintheir RTA behaviors.

A 30GHz Wideband CMOS Injection-Locked Frequency Divider for 60GHz Transceiver

In this paper, a 30 GHz wide locking-range (26.2 GHz-35.7 GHz) direct injection-locked frequency divider (ILFD), which operating in the millimeter-wave (MMW) band, is presented. The locking range of the ILFD is extended by using differential injection topology. Besides, varactors are used in RLC resonant tank for extending the frequency tuning range. The post simulation results show that a wide locking-range of 9.5 GHz (30.7%) is achieved. When the VCO output frequency varies from 26.85 GHz to 34.42 GHz, the proposed ILFD can achieve divide-by-two correctly. Designed in 0.13 μm CMOS technology, the ILFD occupies a core area of 0.76 mm2 while drawing 7 mA of current from 2.5 V power supply.

A Single-Chip UHF RFID Reader Transceiver IC

A single-chip UHF RFID reader transceiver IC has been implemented in 0.18 μm SiGe BiCMOS technology. The chip includes all transceiver blocks as RX/TX RF front-end, RX/TX analog baseband, frequency synthesizer and I2C with fully-compliant China 800/900 MHz RFID draft, ISO/IEC 18000-6C protocol and ETSI 302 208-1 local regulation. The normal mode receiver in the presence of -3 dBm self-jammer achieves -75 dBm 1% PER sensitivity. The linear class-A PA integrated in transmitter has 25 dBm OP1 dB output power for CW. The fully-integrated fractional-N fre-quency synthesizer is designed based on MASH 1-1-1 sigma-delta modulator and 1.8 GHz fundamental frequency LC-VCO for lower in-band and out-of-band phase noise. The measured phase noise is up to -106 dBc/Hz@200 kHz and -131 dBc/Hz@1 MHz offset from center frequency and the integrated RMS jitter from 10 kHz to 10 MHz is less than 1.6 pS. The chip dissipates 330 mA from 3.3 V power supply when transmitting 22.4 dBm CW signal and the PAE of linear PA is up to 26%. The chip die area is 16.8 mm2.

Design and fabrication of computer-generated holograms for testing optical freeform surfaces

Freeform optical surfaces （FOSs） will be the best elements in the design of compact optical systems in the future. However, it is extremely difficult to measure freeform surface with sufficient accuracy, which im- pedes the development of the freeform surface. The design and fabrication of computer-generated hologram （CGH） , which has been successfully applied to the tests for aspheric surfaces, cannot be directly adopted to test FOSs due to their non-rotational asymmetry. A novel ray tracing planning method combined with successively optimizing even and odd power coefficients of phase polynomials in turn is proposed, which can successfully design a non-rotational asymmetry CGH for the tests of FOSs with an F-O lens. A new eight-step fabrication process is also presented aiming to solve the problem that the linewidth on the same circle of the CGH for testing freeform surface is not uniform. This problem cannot be solved in the original procedure of CGH fabrication. The test results of the step profiler show that the CGH fabricated in the new nrocedure meets the reauirements.

Design of a low power 10 bit 300 ksps multi-channel SAR ADC for wireless sensor network applications

This paper presents a low power 10 bit 300 ksps successive approximation register analog-to-digital converter （SAR ADC） which is applied in wireless sensor network （WSN） applications. A single ended energy- saving split capacitor DAC array and a latch comparator with a rail to rail input stage are utilized to implement the ADC, which can reduce power dissipation while expanding the full scale input range and improve the signal-to- noise ratio （SNR）. For power optimization the supply voltage of the SAR ADC is designed to be as low as 2 V. Four analog input channels are designed which make the ADC more suitable for WSN applications. The prototype circuit is fabricated using 3.3 V, 0.35μm 2P4M CMOS technology and occupies an active chip area of 1.23 mm2. The test results show that the power dissipation is only 200μW at a 2 V power supply and a sampling rate of 166 ksps. The calculated SNR is 58.25 dB, the ENOB is 9.38 bit and the FOM is 4.95 p J/conversion-step.

Different Diffusion Behavior of Cu and Ni Undergoing Liquidesolid Electromigration

The diffusion behavior of Cu and Ni atoms undergoing liquidesolid electromigration（L-S EM） was investigated using Cu/Sn/Ni interconnects under a current density of 5.0 103A/cm2 at 250℃. The flowing direction of electrons significantly influences the cross-solder interaction of Cu and Ni atoms, i.e., under downwind diffusion, both Cu and Ni atoms can diffuse to the opposite interfaces; while under upwind diffusion,Cu atoms but not Ni atoms can diffuse to the opposite interface. When electrons flow from the Cu to the Ni, only Cu atoms diffuse to the opposite anode Ni interface, resulting in the transformation of interfacial intermetallic compound（IMC） from Ni3Sn4into（Cu,Ni）6Sn5and further into [（Cu,Ni）6Sn5t Cu6Sn5], while no Ni atoms diffuse to the opposite cathode Cu interface and thus the interfacial Cu6Sn5 remained.When electrons flow from the Ni to the Cu, both Cu and Ni atoms diffuse to the opposite interfaces,resulting in the interfacial IMC transformation from initial Cu6Sn5into（Cu,Ni）6Sn5and further into[（Cu,Ni）6Sn5t（Ni,Cu）3Sn4] at the anode Cu interface while that from initial Ni3Sn4into（Cu,Ni）6Sn5and further into（Ni,Cu）3Sn4at the cathode Ni interface. It is more damaging with electrons flowing from the Cu to the Ni than the other way.

The application of Cu/SiO_2 catalytic system in chemical mechanical planarization based on the stability of SiO_2 sol

There is a lot ofhydroxyl on the surface ofnano SiO2 sol used as an abrasive in the chemical mechanical planarization （CMP） process, and the chemical reaction activity of the hydroxyl is very strong due to the nano effect. In addition to providing a mechanical polishing effect, SiO2 sol is also directly involved in the chemical reaction. The stability of SiO2 sol was characterized through particle size distribution, zeta potential, viscosity, surface charge and other parameters in order to ensure that the chemical reaction rate in the CMP process, and the surface state of the copper film after CMP was not affected by the SiO2 sol. Polarization curves and corrosion potential of different concentrations of SiO2 sol showed that trace SiO2 sol can effectively weaken the passivation film thickness. In other words, SiO2 sol accelerated the decomposition rate of passive film. It was confirmed that the SiO2 sol as reactant had been involved in the CMP process of copper film as reactant by the effect of trace SiO2 sol on the removal rate of copper film in the CMP process under different conditions. In the CMP process, a small amount of SiO2 sol can drastically alter the chemical reaction rate of the copper film, therefore, the possibility that Cu/SiO2 as a catalytic system catalytically accelerated the chemical reaction in the CMP process was proposed. According to the van＇t Hoff isotherm formula and the characteristics of a catalyst which only changes the chemical reaction rate without changing the total reaction standard Gibbs free energy, factors affecting the Cu/SiO2 catalytic reaction were derived from the decomposition rate of Cu （OH）2 and the pH value of the system, and then it was concluded that the CuSiO3 as intermediates of Cu/SiO2 catalytic reaction accelerated the chemical reaction rate in the CMP process. It was confirmed that the Cu/SiO2 catalytic system generated the intermediate of the catalytic reaction （CuSiO3） in the CMP process through the removal rate of copper film, infrared spectrum and AFM diagrams in different pH conditions. FinalLy it is concluded that the SiO2 sol used in the experiment possesses stable performance; in the CMP process it is directly involved in the chemical reaction by creating the intermediate of the catalytic reaction （CuSiO3） whose yield is proportional to the pH value, which accelerates the removal of copper film.

Effect of electrode materials and annealing on metal-semiconductor contact of Ga2O3 with metal

Gallium oxide(Ga2O3) thin films were prepared on Si substrate by magnetron sputtering. The obtained samples were comprehensively characterized by X-ray photoelectron spectroscopy(XPS) and scanning electron microscope(SEM). Ti, Pt, Ni and AZO were deposited on the Ga2O3 thin films as electrodes. This paper mainly studies the metal-semiconductor contact formed by these four materials on the films and the influence of annealing at 500℃ on the metal-semiconductor contact. The I-V characteristics show a good linear relationship, which indicates ohmic contact between Ga2O3 and other electrodes.

A fast face detection architecture for auto-focus in smart-phones and digital cameras

Auto-focus is very important for capturing sharp human face centered images in digital and smart phone cameras. With the development of image sensor technology, these cameras support more and more highresolution images to be processed. Currently it is difficult to support fast auto-focus at low power consumption on high-resolution images. This work proposes an efficient architecture for an Ada Boost-based face-priority auto-focus. The architecture supports block-based integral image computation to improve the processing speed on high-resolution images; meanwhile, it is reconfigurable so that it enables the sub-window adaptive cascade classification, which greatly improves the processing speed and reduces power consumption. Experimental results show that 96% detection rate in average and 58 fps(frame per second) detection speed are achieved for the1080p(1920×1080) images. Compared with the state-of-the-art work, the detection speed is greatly improved and power consumption is largely reduced.

Designing a Phthalonitrile/Benzoxazine Blend for the Advanced GFRP Composite Materials

High performance resin must be used in the high performance glass fiber-reinforced plastic（GFRP） composites, but it is sometimes difficult to balance the processabilities and the final properties in the design of advanced thermoset GFRP composites. In this study, a phthalonitrile/benzoxazine（PPN/BZ） blend with excellent processability has been designed and applied in the GFRP composite materials. PPN/BZ blend with good solubility, low melt viscosity, appropriate gel condition and low-temperature curing behavior could enable their GFRP composite preparation with the prepreg-laminate method under a relatively mild condition. The resulted PPN/BZ GFRP composites exhibit excellent mechanical properties with flexural strength over 700 MPa and flexural modulus more than 19 GPa. Fracture surface morphologies of the PPN/BZ GFRP composites show that the interfacial adhesion between resin and GF is improved. The temperatures at weight loss 5%（T_（5%）） and char residue at 800 °C of all PPN/BZ GFRP composites are over 435 °C and 65% respectively. PPN/BZ GFRP composites with high performance characteristics may find applications under some critical circumstances with requirements of high mechanical properties and high service temperatures.

An 18-bit high performance audio ∑-△D/A converter

A multi-bit quantized high performance sigma-delta（Σ-Δ） audio DAC is presented.Compared to its singlebit counterpart,the multi-bit quantization offers many advantages,such as simplerΣ-Δmodulator circuit,lower clock frequency and smaller spurious tones.With the data weighted average（DWA） mismatch shaping algorithm,element mismatch errors induced by multi-bit quantization can be pushed out of the signal band,hence the noise floor inside the signal band is greatly lowered.To cope with the crosstalk between digital and analog circuits,every analog component is surrounded by a guard ring,which is an innovative attempt.The 18-bit DAC with the above techniques,which is implemented in a 0.18μm mixed-signal CMOS process,occupies a core area of 1.86 mm^2.The measured dynamic range（DR） and peak SNDR are 96 dB and 88 dB,respectively.