Large-rotation and low-voltage driving of micromirror realized by tense thin-film torsion bar

An electrostatically driven micromirror device using a thin-film torsion bar is proposed. The mirror rotation angle of 7.3/spl deg/ at 5 V is demonstrated at the nonresonant condition. A bulk Si micromirror is suspended by SiN thin-film torsion bars. Inside the torsion bar, the tension having the magnitude larger than that of the driving force is included. The torsion bar can have a compliance with the mirror rotation and the rigidity against the unwanted motions (e.g., vertical displacement or in-plane rotation).     

Laterally actuated torsional micromirrors for large static deflection

We report on the implementation of laterally electrostatically actuated, torsionally suspended silicon-on-insulator (SOI) micromirrors with a static optical deflection angle of over 40/spl deg/ peak-to-peak. Decoupling the actuator and mirror design allows for large actuator arrays, allowing large dc deflection angle and high resonant frequency to coexist in the same device. The micromirror structures are fully monolithic, micromachined from the front side and back side of an SOI wafer-device layer. In-plane actuation is transformed into out-of-plane motion and rotation, enabling integration of a wide variety of SOI-MEMS sensors, actuators, and micromirrors. When operated in resonance at 1321 Hz, a typical device measured up to 92/spl deg/ peak-to-peak optical deflection at 127 Vdc with 15 Vac amplitude.     

A high-speed low-voltage double-switch optical crossconnect using stress-induced bending micromirrors

A high-speed low-voltage double-switch electrostatically actuated optical crossconnect (OXC) is demonstrated using stress-induced bending micromirrors. A curved polysilicon seesaw structure substantially lowers the electrostatic operating voltage of the OXC and provides a double-switch option. Large mirror deflection angles of 13/spl deg/ (mirror elevation of 290 /spl mu/m high) and 5/spl deg/ (cantilever deflection of 90 /spl mu/m high), corresponding to low operating voltages of 25 and 18 V, could be obtained. A submillisecond switching time (<850 /spl mu/s), a low optical insertion loss (0.65 dB), and a small polarization-dependent loss (<0.08 dB) are achieved.     

Performance of a raster scanning laser display system using diamond shaped frame supported micromirror

We describe the design, fabrication, and experimental results of a raster scanning laser display system using micromachined electrostatic scanning micromirror. The micromirror is comprised of a diaphragm mirror plate supported by an array of diamond shaped support frame, and movable comb electrodes. A prototype raster scanning laser display system using the fabricated micromirror, having optical scan angle of 16.9/spl deg/ at resonance frequency of 19.55 kHz, as the horizontal scanner was developed and tested. To compensate for the nonlinear characteristics of the scanner, a simple image correction method was developed, and the projected image was analyzed and compared with the simulation results.     

Fabrication and characterization of polymer optical waveguides with integrated micromirrors for three-dimensional board-level optical interconnects

This paper describes the fabrication and characterization of optical/electrical printed circuit boards (O/E-PCB) with embedded multimodal step index (MM-SI) waveguides and integrated out-of-plane micromirrors (IMMs) for three-dimensional (3-D) optical interconnects. Optical circuitry is built up on PCBs using UV lithography; 45/spl deg/ input/output (I/O) couplers are fabricated by inclined exposure. Commercial polymers are used as optical core and cladding materials. Critical mirror properties of angle, surface quality, reflectivity, and coupling efficiency are characterized experimentally and theoretically. Optical and scanning electron microscopy, white light interferometry, and fiber scanning method are used in the investigations. Sloping profiles measured as a function of the incident light showed the attainment of mirror angles of /spl alpha/=36/spl deg/-45/spl deg/ with /spl plusmn/2/spl deg/ consistency. Near-field optical imaging with a white light source showed that out-of-plane beam turning was achieved. Topography investigations revealed a rectilinear negative tapering shape regardless of the incoming beam angle or type of substrate. However, higher substrate reflectancy was observed to lower the mirror angle. The average propagation loss measured for 10-cm-long waveguides at /spl lambda/=850 nm by the cut-back method was 0.60 dB/cm; the excess loss calculated for the mirror coupling was 1.8-2.3 dB. The results showed that the IMMs can be incorporated in O/E-PCBs to couple light in and out of planar waveguides. Furthermore, the presented results indicate that optical waveguides with integrated micromirrors for optical 3-D wiring can be produced compatible with volume manufacturing techniques.     

静电梳齿驱动器薄膜变形反射镜

提出一种大冲程静电梳齿驱动器微机械薄膜变形反射镜,理论上研究了静电梳齿驱动器微机械薄膜变形反射镜的静电驱动力和变形位移与驱动电压的关系,分析了变形反射镜的驱动稳定性,比较了平板电容驱动器与纵向梳齿驱动器的驱动能力.结果表明,变形反射镜的静电驱动力和变形位移没有关系;在相同的面积下,纵向梳齿驱动器的驱动力比平板电容驱动器的驱动力大很多.     

Monolithic 2-D scanning mirror using self-aligned angular vertical comb drives

We have demonstrated microfabricated, monolithic two degrees of freedom (two-dimensional) electrostatic torsional mirrors using a three-mask process on silicon-on-insulator wafer with a single plastic deformation step. The mirror operated independently in two orthogonal directions as controlled by two sets of self-aligned angular vertical combs. The measured dynamic performance showed resonant frequencies of 10.56 and 1.54 kHz with optical scanning angles up to 27/spl deg/ and 20/spl deg/ in the two orthogonal axes, respectively, under driving voltages of 20 V/sub dc/ plus 15 V/sub pp/. A 90-day continuous mirror operation at peak resonance, in equivalent to 80 and 12.1 billion cycles on the two orthogonal axes, showed negligible performance variations.     

A two-terminal IC temperature transducer

A bipolar monolithic IC temperature transducer with an operating temperature range of -125/spl deg/C to +200/spl deg/C has been designed, fabricated, and tested. The two-terminal device, which is fabricated using laser trimmed thin-film-on-silicon technology, is a calibrated temperature dependent current source with an average output impedence of 10 M/spl Omega/ over the 3.5-V to 30-V range of input voltage. Overall absolute accuracies of /spl plusmn/0.5/spl deg/C from -75/spl deg/C to +150/spl deg/C have been achieved on a scale of 1 /spl mu/A/K under optimum operating conditions.     

Single Ping-multiple measurements: sonar bearing angle estimation using spatiotemporal frequency filters

Presented is a mixed-signal full-custom VLSI chip designed to receive sonar return signals from an ultrasonic microphone array, and extract input bearing angles of the incoming signals. Processing utilizes simple low-power analog spatiotemporal bandpass filters to extract wavefront velocity across the array, which translates to input bearing angle. Processing uses phase information of array signals, not onset or offset of ultrasonic burst. With such synchronous processing, multiple angle readings from different returns of the same ultrasonic transmit burst are possible. Compatible microphone arrays are compact in size-test array has a total baseline of 26.5 mm. In a test with ultrasonic beacon 65 cm from a microphone array, angular precision of 1/spl deg/ was demonstrated in most instances in the range -60/spl deg/ to 60/spl deg/. Applications include sonar localization of remote objects, sonar imaging, and improved interference rejection between objects within the field of view of the sensor microphones. The chip was fabricated on a standard 3M2P CMOS process with a 0.5-/spl mu/m feature size.     

Compact packaging of optical and electronic components for on-board optical interconnects

An optical interconnection plate was developed in order to achieve a compact and cost-effective interconnection module for an optical data link between chips on printed circuit boards. On the silica substrate, transmission lines and solder bumps are formed on the top surface of the substrate, and polymer waveguide array with 45/spl deg/ mirror planes is formed on the back side. This optical interconnection plate technique makes the alignment procedure quite simple and economical, because all the alignment steps between the optical components can be achieved in wafer processes and a high accuracy flip-chip bonding technique. We confirmed the sufficiently high coupling efficiency and low optical crosstalk using the simplified experimental setup. Flip-chip bonding of the vertical-cavity surface-emitting laser and photodiode arrays on the top surface of the optical interconnection plate was performed using indium bumps in order to avoid thermal damage of the polymer waveguide. The fully packaged optical interconnection plate showed an optical data link at rates of 455 Mb/s. Improvement of the mirror surface roughness and the mirror angle accuracy could lead to an optical link at higher rates. In addition, the interconnection system can be easily constructed by inserting the optical interconnection plate between the processing chips or data lines requiring optical links.     

Parallel optical transmitter module using angled fibers and a V-grooved silicon optical bench for VCSEL array

We propose an advanced structure of optical subassembly (OSA) for packaging of the vertical-cavity surface-emitting laser (VCSEL) array, using (111) facet mirror of the V-groove ends formed in a silicon optical bench (SiOB) and angled fiber apertures. The feature of our OSA can provide a low optical crosstalk between neighboring channels, a low feedback reflection, and a large misalignment tolerance along the V-groove. We describe the optimized design of fiber angle, VCSEL position, and fiber position. The fabricated OSA structure consists of 12 channels of angled fiber array, 54.7/spl deg/ V-grooves, Au-coated mirrors on (111) end facet of the V-grooves, and flip-chip-bonded VCSEL array on a SiOB. In this structure, the beam emitted from the VCSEL is deflected at the 54.7/spl deg/ mirror of (111) end facet and propagated into the angled fiber. The angled fiber array was polished by 57/spl deg/. Fabricated OSAs showed a coupling efficiency of 30%-50% that is 25 times larger than that obtained from an OSA with a vertically flat fiber array. Our OSA showed large misalignment tolerance of about 90 /spl mu/m along the longitudinal direction in the V-groove. We fabricated a parallel optical transmitter module using the OSA and demonstrated 12 channels /spl times/2.5 Gb/s data transmission with a clear eye diagram.     

The control of channeling phenomenon

The dependence of depth profile on a tilt and twist angle was investigated with a resolution of 0.05/spl deg/ using a stencil mask ion implanter that has less than 0.1/spl deg/ parallelism of ion beam. Angular dependence of depth profiles obtained by secondary ion mass spectrometry (SIMS) shows the channeling phenomenon can be controlled using a highly controlled parallel ion beam. This means that if tilt angle is controlled with a resolution of less than 0.1/spl deg/, the variation caused by channeling phenomenon can be neglected. The threshold voltage data of n-type MOSFETs fabricated using a controlled parallel ion beam with resolution of less than 0.1/spl deg/ indicates that the variation is the same as that in the case of one fabricated using 7/spl deg/ implantation.     

A high power MOSFET with a vertical drain electrode and a meshed gate structure

A MOSFET with a maximum power of 200 W in a 5/spl times/5 mm/SUP 2/ chip which exhibits 20-A current, 3000-millimho transconductance and 100-V breakdown voltage has been developed. The features of the device structure are a vertical drain electrode which makes it possible to use most of the surface area for the source electrode, and a meshed gate structure which realizes an increase in the channel width per unit area. The p-channel device with an offset gate structure was fabricated from an n on p/SUP +/ epitaxial wafer by using polysilicon gate and ion implantation processes. The device can be operated stably at ambient temperatures up to 180/spl deg/C. While the bipolar transistor is a suitable power device in the low voltage region, the MOSFET looks more promising in the high voltage region than the V-FET and the bipolar transistor.     

MOS transistors operated in the lateral bipolar mode and their application in CMOS technology

Operation of an MOS transistor as a lateral bipolar is described and analyzed qualitatively. It yields a good bipolar transistor that is fully compatible with any bulk CMOS technology. Experimental results show that high /spl beta/-gain can be achieved and that matching and 1/f noise properties are much better than in MOS operation. Examples of experimental circuits in CMOS technology illustrate the major advantages that this device offers. A multiple current mirror achieves higher accuracy, especially at low currents. An operational transconductance amplifier has an equivalent input noise density below 0.1 /spl mu/V//spl radic/Hz for frequencies as low as 1 Hz and a total current of 10 /spl mu/A. A bandgap reference yields a voltage stable within 3 mV from -40 to +80/spl deg/C after digital adjustment at ambient temperature. Other possible applications are suggested.     

Crosstalk-minimized polymeric 2/spl times/2 thermooptic switch

A thermooptic 2/spl times/2 switch based on the total internal reflection effect is demonstrated. The device, made of ultraviolet curable fluorinated polymer, has an increased half-branch angle of 5/spl deg/. The purpose of a large half-branch angle is to overcome the volume relaxation phenomenon, which is an intrinsic characteristic of polymers. The device successfully decreases the crosstalk below -40 dB in both the cross and bar states. The fabricated device has a power consumption of only 66 mW in the bar state.     

High-frequency, stripline, multireflection electrooptic beam deflectors

A novel electrooptic (EO) beam deflector has been designed through numerical simulation. This stripline lithium tantalate device has the potential to electrooptically modulate the deflection of an optical pulse at unprecedented frequencies. Velocity matching of the optical pulse to a high-frequency transmission line signal is achieved through reflections of the fast optical pulse. An optimal design criterion is formulated for this device. Deflection capability is estimated to be 8/spl deg/. The device is intended for use in deflection-based optical analog-digital (A/D) conversion.     

Highly scalable 2-D fiber collimator array based on an array of through-holes in silicon

A highly scalable 4/spl times/4 fiber collimator array with long collimation length has been fabricated by utilizing a two-dimensional array of precision-controlled through-holes in silicon. A fiber array and a lens array were prepared by precisely positioning corresponding fibers and lenses utilizing the holes in separate silicon substrates, and the two arrays were integrated to implement the collimator array. The achieved average angular pointing accuracy and positioning accuracy of the collimator array were about 0.1/spl deg/ and better than 2 /spl mu/m, respectively. At a distance of 10 cm from the collimator, the measured collimated beam size was 400 /spl mu/m with its full divergence angle of 0.18/spl deg/.     

Measurements of a fabricated micro mirror using a lateral-effectposition-sensitive photodiode

The characteristics of a fabricated micro mirror were determined using an optical measurement system. The system consisted of a helium-neon laser, a p-i-n lateral-effect photodiode, and other fundamental optical elements. For testing, we used a micro mirror array (1×4) in which each mirror was composed of a mirror plate, two torsional flexure hinges, two address electrodes, and two support posts. A mirror plate was designed to a size of 100×110×1.5 μm ³ and the hinge size was 20 μm long, 5 μm wide, and 0.5 μm thick. The micro mirror array was fabricated using micromachining technology and a lithography-galvanoformung-abformung-like process using nickel electroplating. The variation in the mirror's deflection angle with applied voltage was measured as a static characteristic. The downward threshold voltage of the 0.5-μm thick hinge was 48 V. The step response time, as a dynamic characteristic, was 21.8 μs when a 64 V step voltage higher than the downward threshold voltage was applied to an address electrode. The lifetime of the fabricated micro mirror was tested for both unidirectional and bidirectional operation     

Fabrication and current-drive of SiGe/Si 'Micro-origami' epitaxial MEMS device on SOI substrate

A micromirror structure with SiGe/Si heteroepitaxial layer on a silicon-on-insulator (SOI) substrate using a 'Micro-origami' technique has been successfully fabricated. The micromirror is supported by two curved hinge structures. The device is driven by application of a current, and net angular displacements larger than 10/spl deg/ (static) and 30/spl deg/ (in resonance) were obtained. These values are comparable with or even larger than the reported values for other MEMS optical switches or beam scanning devices. The experimental results suggest that the movement is evoked by a thermal effect. The Micro-origami device has advantages of low operation voltage smaller than 2 V, and structural compatibility with the Si or SiGe LSIs.     

A new single-chip C/SUP 2/MOS A/D converter for microprocessor systems-Penta-Phase Integrating C/SUP 2/MOS A/D converter

A new unique conversion technique named the `Penta-Phase Integration' method, applied to a single-chip C/SUP 2/MOS 12-bit analog-to-digital converter designed for microprocessor system, is introduced and described. The newly developed device, fabricated with a standard metal gate CMOS process including an 8-channel multiplexer and TTL compatibility, has several features: unipolar- and ratiometric-conversion can be performed; conversion accuracy within /spl plusmn/0.05 percent of full scale over the -35/spl deg/C-+85/spl deg/C temperature range can be obtained; conversion time is 1.1 ms at a 20 MHz clock frequency, and the device can be operated with a single 5 V power supply and 6 mW power consumption at a 4 MHz clock frequency. The new technique essentially incorporated several methods which divide one conversion cycle into five-phases, accomplish minimization of the error caused by comparator response delay, provide several narrow flat phases to eliminate switching errors due to parasitic capacitance, and enable high clock frequency operation in digital circuits by utilizing C/SUP 2/MOS circuit technology and a synchronized configuration for counters.