Hung D. Nguyen

A scanning micromirror with angular comb drive actuation

Describes a single crystal silicon, 1/spl times/1 mm/sup 2/, scanning micromirror, which incorporates a novel angular vertical comb drive actuator. Results from our model for the angular vertical comb show that a 50% higher scan angle can be achieved when compared to a staggered vertical comb of equivalent dimensions. The simplified, cost effective, silicon on insulator micro-electromechanical systems, (SOI MEMS), process features self-alignment of the fixed and moving teeth and is fabricated on a single SOI wafer. Static deflection for our fabricated device fits well with the model and a resonant mode optical scan angle of /spl plusmn/18/spl deg/ at 1.4 kHz has been measured.

Theory and experiments of angular vertical comb-drive actuators for scanning micromirrors

We report on the theory and experiments of scanning micromirrors with angular vertical comb-drive (AVC) actuators. Parametric analyses of rotational vertical comb-drive actuators using a hybrid model that combines two-dimensional finite-element solutions with analytic formulations are described. The model is applied to both AVC and staggered vertical comb-drive (SVC) actuators. Detailed design tradeoffs and conditions for pull-in-free operations are discussed. Our simulation results show that the fringe fields play an important role in the estimation of maximum continuous rotation angles, particularly for combs with thin fingers, and that the maximum scan angle of the AVC is up to 60% larger than that of the SVC. Experimentally, a large dc continuous scan angle of 28.8/spl deg/ (optical) has been achieved with a moderate voltage (65 V) for a 1-mm-diameter scanning micromirror with AVC actuators. Excellent agreement between the experimental data and the theoretical simulations has been obtained.

Angular vertical comb-driven tunable capacitor with high-tuning capabilities

This paper reports on a novel tunable capacitor with electrostatic angular vertical comb-drive (AVC) actuators. The AVC tunable capacitor creates a large offset in comb fingers through a small rotation angle-an advantage not found in conventional lateral comb-drive devices. High capacitance and large continuous tuning ratio is achieved in a compact device area. The largest tuning varactor demonstrates capacitance values between 0.27-8.6 pF-a tuning ratio of more than 31:1, the highest ever reported. The maximum quality factor Q is 273 at 1 GHz near the minimum capacitance value.

A low voltage, large scan angle MEMS micromirror array with hidden vertical comb-drive actuators for WDM routers

A MEMS micromirror array with hidden vertical comb-drive actuator and springs has been successfully demonstrated. The devices were fabricated using SUMMiT-V process. The fabricated micromirror showed large optical scan angle (24/spl deg/) and low actuation voltage (9 V). The fill-factor of the micromirror array was as high as 91%. Applications of the micromirror array for WDM routers are also discussed.

A substrate-independent wafer transfer technique for surface-micromachined devices

We report on a new wafer transfer technique that can remove and transfer surface-micromachined layers to application-specific substrates. This process, however, is not limited to only MEMS devices and can be applicable to other semiconductor devices. Successful transfer of a 1 cm/spl times/1 cm MEMS chip with electrostatically actuated curled cantilever switches to a transparent quartz substrate has been demonstrated. Pull-in voltage for transferred devices is 31 V compared with 23 V for devices on standard silicon substrates.

Monolithically cascaded micromirror pair driven by angular vertical combs for two-axis scanning

In this work, monolithically cascaded one-axis micromirrors driven by angular vertical comb drives are designed and fabricated. Using W-shaped folded-beam optics, we demonstrate two-axis scanning covering /spl plusmn/6.0/spl deg/ two-dimensional area at resonant modes of 7.5 kHz, /spl plusmn/17 V for a fast-scanning mirror and 1.2 kHz, /spl plusmn/7 V for a slow-scanning mirror. The experimental results satisfy the requirements for a surveying instrument.

Device transplant of optical MEMS for out of plane beam steering

We report on a substantially improved process for which an array of optical MEMS devices (MOEMS) are batch transferred onto a quartz wafer such that through wafer beam scanning can be achieved. MEMS optical scanners are successfully fabricated, transferred, and actuated for out-of-plane beam steering. DC transfer curves of control devices on silicon and those transferred on quartz exhibit similar pull in voltages of 135 V and 142 V respectively. Similarly, resonance for control device peaked at 1.1 kHz while transferred devices exhibit higher resonance at 1.2 kHz.

Cascaded micromirror pair driven by angular vertical combs for two-axis scanning

In this work, monolithically cascaded one-axis micromirrors driven by angular vertical comb drives are designed and fabricated. Using W-shaped folded-beam optics, we demonstrate two-axis scanning covering /spl plusmn/6.0/spl deg/ two-dimensional area at resonant modes of 7.5 kHz, /spl plusmn/17 V for a fast-scanning mirror and 1.2 kHz, /spl plusmn/7 V for a slow-scanning mirror. The experimental results satisfy the requirements for a surveying instrument.