邻近导体布局对电光测量的影响

采用静态有限差分法，求解了电光探测时探头内部的电场分布；发现了电光信号随布线的变化，设计了一系列不同布线的电极；采用ITO导电膜进行电光信号幅度校准并减少串扰。理论分析与实验结果符合得很好。最后，分析了ITO导电膜对CMOS反相器高频特性的影响。     

Laser-based electro-optic testing of multichip module structures

Laser-based electro-optic probing is a proven noninvasive technique for testing high-speed microwave circuits on substrates such as gallium arsenide (GaAs) and indium phosphide (InP). We have extended this technique to probe circuit structures on doped and poled polyimide substrates that are useful in high-density packaging applications such as multichip modules (MCMs). Our results demonstrate the potential to improve the testability of MCMs by probing circuit structures that are buried in the central layers of an MCM. In addition to direct, point-by-point electric field measurements in representative MCM structures, we have investigated the poled polyimide dielectric efficacy both as a dielectric circuit layer and as a suitable electro-optic material.     

Electro-optic sampling using an external GaAs probe tip

The first laser-diode-based external electro-optic (EO) sampling using a GaAs probe tip is described. This tip is a longitudinal electric field sensor, being therefore immune from optical crosstalk. The minimum detectable voltage is 16 mV/ square root (Hz). The EO sampling is compared with that of a conventional electrical sampling oscilloscope, and the two are shown to be in excellent agreement.<>     

Optical intensity modulator based on a novel electrooptic polymerincorporating high μβ chromophore

We have synthesized a novel electrooptic (EO) polymer based on a high μβ chromophore incorporating tricyanobutadiene acceptors. A crosslinked polyurethane network was also adopted to enhance its thermal stability. In order to find the optimum poling condition for the polymer, the influence of the electric poling profile on optical characteristics such as the EO effect, thermal stability, and damage was investigated. Then a high-speed intensity modulator using the EO polymer was designed and fabricated. The measured half-wave voltage V_π was 4.5 V at the wavelength of 1.31 μm. Accordingly, the achieved EO coefficient r₃₃ was as high as 25 pm/V, and the thermal stability of the poled polymer was as high as 95°C. Finally, the modulator was successfully operated up to 40 GHz     

Design and performance of a polymer Mach-Zehnder interferometer electro-optic modulator at 1.55 μm

Based on poled guest-host electro-optic (EO) polymer DR1/SU-8, a Mach-Zehnder interferometer (MZI) EO modulator operated at 1.55 μm is proposed. For achieving high response speed and high EO modulation efficiency, both waveguide structure and electrode structure are especially optimized. The impedance match and less index mismatch are achieved. The final characteristic impedance of electrode is about 49.4 Ω, and the microwave index and the light-wave index are 1.5616 and 1.6006, respectively. The device is fabricated using wet-etching technique and inductively coupled plasma (ICP) etching technique, and its performance is measured at 1.55 μm. Experimental results show that when the applied voltage is tuned, the modulator can be changed from ON state to OFF state. The insertion loss at ON state is 12 dB and the extinction ratio between ON and OFF states is about 10 dB. The high response speed is in nano-second level for a square-wave signal. Therefore, the modulator possesses potential applications in high-speed optical networks on chip.     

Optical intensity modulators using diazo-dye-substituted polymerchannel waveguides

The electrooptic (EO) modulation of 1.32 μm laser light is measured in Mach-Zehnder channel waveguides fabricated with diazo-dye-substituted polymers with coplanar-waveguide (CPW) or microstrip (MS) electrodes. Two types of channel waveguide fabricated by photobleaching or O₂ reactive-ion etching (RIE) exhibit the same EO coefficients r₃₃ under the same poling condition. However, the photobleached waveguides show a lower half-wave voltage than the RIE-fabricated ones because of both the optical power concentration in a core layer and the existence of an EO active cladding layer. These tendencies are well explained by considering “effective” overlap integrals between the optical and electric fields, including the distribution of EO-active regions. The maximum r₃₃ value (26 pm/V) of the poled diazo-dye-substituted polymer is obtained with an RIE-fabricated MS-modulator     

Hybrid Integrated Cascaded 2-bit Electrooptic Digital Optical Switches (DOSs)

Hybrid integrated cascaded 1 times 4 electrooptic (EO) polymeric digital optical switches (DOSs) are proposed and demonstrated. The hybrid integration of passive polymer on the same chip with EO polymer can lower the overall device loss without affecting the EO effects. The cascaded DOS can be controlled by only two voltage signal sources without bias stabling mechanism. The device can be operated as a 2-bit reconfigurable switch. The switching voltage is around 15 V for single arm driving with reasonable extinction ratio (9~12 dB) and the loss is improved by ~2.5 dB. This device is ideal for implementing variable optical delay network     

Optical circular-polarization modulator employing tilt-poled electrooptic polymers

A polymer-based integrated circular-polarization modulator (CPM) is demonstrated in this paper. Tilted poling is adopted to achieve polarization conversion in the electrooptic (EO) polymeric waveguide and then realize the power balance between transverse electric and transverse magnetic modes. Detailed analysis and experiments on polarization conversion are presented. The tensor nature of poled polymeric materials is used to generate the phase difference. Contact poling is applied to perform tilted poling and activate the EO effect of polymeric materials. With appropriate voltage control, the polarization state of the output from the CPM can alternate between the left and right-hand-circular states. The extinction ratios at the 45/spl deg/- and -45/spl deg/-tilted linearly polarized states are larger than 25 dB.     

Electrooptic sampling of a packaged high-speed GaAs integratedcircuit

The authors describe the use of electrooptic sampling to characterize the performance of a packaged 1.7-GHz GaAs planar integrated decision circuit. To study the packaged device, it was necessary for the optical probe beam to impinge on the circuit from the front (active) side. This geometry enabled effective evaluation of the circuit, in spite of reduced spatial resolution and voltage sensitivity compared to a backside probing geometry. Using a gain-switched InGaAsP laser source, waveforms have been measured in the D flip-flop within the circuit and propagation delays of about 25 ps in the input buffers. Apparent crosstalk has been measured when the probe is positioned between adjacent active circuit lines and it is found that this crosstalk depends sensitively on the position of the probe beam     

Backside probing of flip–chip circuits using electrostatic force sampling

A non-contact scanning probe microscopy technique for measuring high-frequency voltage waveforms from the backside of a flip-chip mounted integrated circuit is presented. The signals on interconnects on the frontside of the die are accessed by mechanical thinning and focused ion beam milling through the backside of the die. A scanning force microscopy micromachined probe is placed inside the focused ion beam hole so that it is in close proximity to the circuit measurement point. Internal circuit voltage waveforms are measured by using the scanning probe in a non-contact mode and sensing the local electrostatic force on the tip of the probe. The instrument currently has a 3 GHz bandwidth and a capacitive loading on the test point of less than 1 fF. The output waveforms from ring oscillator flip-chip test circuits are measured.     

染料掺杂的聚合物波导膜的制备及电光性质的研究

用溶液沉积的方法制备了染料分散红掺杂的聚苯乙烯膜,并用电场取向的方法对膜中的染料极性分子进行了取向。对取向膜进行的电光测试结果表明取向膜的电光系数r_(33)≈35pm/V较无机晶体要大。     

Electrooptic light modulation and second-harmonic generation in novel diazo-dye-substituted poled polymers

The nonlinear-optical susceptibilities, x/sup (2)/, of a diazo-dye-substituted polymer poled with high electric fields were determined experimentally and theoretically. The electrooptic modulation of He-Ne laser light in a traveling-wave channel-waveguide modulator using the diazo-dye-substituted poled polymer is reported, and the linear electrooptic coefficient of the poled polymer is estimated from a measured half-wave voltage. The polymer studied is a poly(methyl methacrylate) copolymerized with a methacrylate ester of the dicyanovinyl-terminated diazo dye derivative. This polymer is called 3RDCVXY. The corona-poled 3RDCVXY polymer exhibits a x/sup (2)/ value of 1*10/sup -6/ esu at 1.06 mu m. The thermal stability is excellent even at 80 degrees C. The poled 3RDCVXY polymer film shows a linear electrooptic coefficient as high as 40 pm/V at 0.633 mu m. An electrooptical light modulation in the channel 3RDCVXY polymer waveguides with a half-wave voltage as low as 5 V was obtained.<>     

基于液态膜的集成电路电光检测技术

利用液态膜作为电场探测的电光材料。液态膜的探测电压灵敏度比Ga舡材料高2个数量级。其原理是,基于液态极性分子的取向极化,液态膜的折射率受电场调制,从而实现电光测量。实验结果表明,在调制电场1kHz频率下测量液态膜电光系数达到95pm／V。利用液态膜对集成电路进行检测具有简单、高效的特点,很好地完成了低频场探测中弱信号的...     

Silicon cantilever arrays with by-pass metal through-silicon-via (TSV) tips for micromachined IC testing probe cards

In this paper, an integrated probe card is proposed and developed for wafer-level IC testing. Based on micromachining technology, totally about 26,000 cantilever-tip probes can be formed simultaneously in one 4-in. silicon wafer, with the minimum pitch of 35 μm for adjacent probing tips. The probe card is designed with a novel composite structure that combines both single-crystalline silicon and electroplated metals. In the composite structure, a novel bypass through-silicon-via with a low aspect ratio can be high-yield fabricated for transferring the testing signals from the probing sided (at the wafer bottom side) to the I/O interface (at the front side). The probe card makes full use of the advantages of the single-crystal silicon and the electroplated nickel and copper. Bulk micromachined silicon cantilevers behave uniform probing height and a good elastic deformation property, while the electroplated nickel probing tips promise high hardness and satisfactory electric contact performance with the dies-under-test (DUT). Measurements show that the fabricated cantilever is able to withstand a contact force of 80mN by a tip displacement of 20 μm. The measured contact resistances on metal pads (Al, Cu, and Au) are all below 1 Ω, whereas the maximum current leakage is 64 pA for 3.3 V voltage across two adjacent tips. After a probing reliability test of 100,000 cycles, the cantilever-tip shows no sign of any performance degradation.     

Analysis of E-O polymer mode converter with bottom transverse poling electrodes

The operation of integrated-optics electrooptic (EO) polymer modulators relies on the Pockel effect that is generated by applying an electric field to the optical waveguides. Birefringent behavior occurs because of the dipole realignment of the poled polymer film. In this paper, the static-field analysis of the electric field distribution for the mode converters with bottom transverse electrodes incorporating a buffer layer was done by using an efficient discrete Fourier transform domain technique. According to the numerical analysis results, the electric-field distribution in the guiding layer is the function of electrode geometric configuration. Two parameters, the electrode width and spacing, were considered for the optimum arrangements of the coplanar electrodes deposited on the polymer waveguide modulator. Also studied was the influence of the asymmetric electrode width of the coplanar electrodes on the sample surface.     

The development of poled polyimide dielectric layers for simultaneous testing and light guiding applications in MCM-Ds

Noninvasive techniques for measuring electric field strengths in multichip module (MCM) substrates can be extremely important in determining ultimate module performance. Certain polymers such as polyimide exhibit an electro-optic response, after appropriate doping and poling, that permits direct measurement of the internal fields with a laser probe. We have built MCM circuit structures using electro-optic polyimides for the dielectric layer. We report thermal, electrical, optical, and electro-optic properties for these dielectric layers. The optical properties of doped and poled polyimides make them attractive for building optical waveguides. We report results for poled polyimide use in both multiple layer structures and optical waveguide formation, and recommend processing guidelines. Further development of doped and poled polyimides may permit optical and electrical interlayers on the same thin-film MCM-D structure.     

Application of a Genetic Algorithm to the Design Optimization of a Multilayer Probe Card for Wafer-Level Testing

The number of input and output pads on high-performance IC devices has increased in recent years, and hence wafer-level testing is conventionally performed using a probe card with a multilayer needle layout. This paper employs ANSYS commercial software and a Genetic Algorithm (GA) to optimize the design parameters of a multilayer needle probe card such that the scrub marks produced by the different needle layers are of approximately equal length. A dummy probe card containing both a conventional multilayer needle layout and the optimized needle layout is then fabricated and used in a series of single-contact probing tests. The results reveal that the scrub marks produced by the optimized needle layout are both shorter and of a more uniform length that those produced by the conventional needle design. For both needle layouts, a lower and more stable contact resistance is obtained as the overdrive distance is increased. Finally, a multicontact probing test is performed to evaluate the effect on the contact resistance of probe tip contamination following repeated surface contacts. The results show that the needles in the optimized layout are less heavily contaminated than those in the conventional layout, and hence the contact resistance is both lower and more stable. As a consequence, the probe card requires cleaning less frequently and hence its service life is improved.     

Characterization of fritting phenomena on Al electrode for low contact force probe card

We have investigated the characteristics of fritting of thin oxide film on an aluminum electrode for application to a probe card with low contact force. The fritting is a kind of electric breakdown of oxide film on metal electrode. It can be utilized for making electric contacts between the test probe and the electrode on LSI chips without a large force. The voltage and the contact force needed to cause fritting on a sputtered Al film was measured using W, BeCu and Pd needle probes. The contact resistance was also measured. A fritting was occurred by applying a contact load of 1 mN and voltage of 5 V. The contact resistance decreases with increasing the maximum current that passes through the contact. A current of 500 mA is enough to obtain the contact resistance of 1 /spl Omega/, which is low enough in practical test of signal lines. No damages were found on the Al film by optical microscope and scanning electron microscope observation.     

一种基于0.18μm CMOS工艺的上电复位电路

介绍了一种采用0.18μm CMOS工艺制作的上电复位电路。为了满足低电源电压的设计要求,采用低阈值电压(约0V)NMOS管和设计的电路结构,获得了合适的复位电压点;利用反馈结构加速充电,提高了复位信号的陡峭度;利用施密特触发器,增加了电路的迟滞效果。电路全部采用MOS管设计,大大缩小了版图面积。该上电复位电路用于一种数模混合信号芯片,采用0.18μm CMOS工艺进行流片。芯片样品电路测试表明,该上电复位电路工作状态正常。     

非均匀分布的纳米银掺杂的聚合物分散液晶全息光栅等效电路建模

聚合物分散液晶全息光栅具有电场可调的特点,材料中掺杂纳米银颗粒,能够有效降低光栅的驱动电压.由于聚合动力学的影响,会造成纳米银颗粒在光栅中的非均匀分布,即纳米银在聚合物和液晶区分布含量不均匀,表现出不同的电场调控特性.通过等效电路建模的方法研究驱动电压阈值与所施加交流电场的频率之间的关系.根据Maxwell-Wagner效应建立纳米银分别被液晶和聚合物包围的等效电路模型,具体研究在液晶条纹中,纳米银含量占总纳米银比例不同的条件下,纳米银掺杂的聚合物分散液晶全息光栅的介电弛豫时间和弛豫振荡的频率数值变化,进一步调节驱动电场频率,获得更低的驱动电压阈值.通过最优驱动电场频率范围来初步确定纳米银在光栅中的分布结构,并证明纳米银颗粒集中在液晶条纹,少量分布在聚合物条纹中.