Pamela R. Patterson

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.

Surface- and bulk- micromachined two-dimensional scanner driven by angular vertical comb actuators

In this paper, we present the design, fabrication, and measurements of a two-dimensional (2-D) optical scanner with electrostatic angular vertical comb (AVC) actuators. The scanner is realized by combining a foundry-based surface-micromachining process (Multi-User MEMS Processes-MUMPs) with a three-mask deep-reactive ion-etching (DRIE) postfabrication process. The surface-micromachining provides versatile mechanical design and electrical interconnect while the bulk micromachining offers high-aspect ratio structures leading to flat mirrors and high-force, large-displacement actuators. The scanner achieves dc mechanical scanning ranges of /spl plusmn/6.2/spl deg/ (at 55 Vdc) and /spl plusmn/4.1/spl deg/ (at 50 Vdc) for the inner and outer gimbals, respectively. The resonant frequencies are 315 and 144 Hz for the inner and the outer axes, respectively. The 1-mm-diameter mirror has a radius of curvature of over 50 cm. [1454].

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.

Heterogeneous wafer-scale integration of 250nm, 300GHz InP DHBTs with a 130nm RF-CMOS technology

The performance advantages of InP based devices over silicon devices are well known, but the ability to fabricate complex, high transistor count ICs is limited both by the relative immaturity of the material system and a limited commercial market. Silicon based devices have made significant advances in device performance, but have not yet matched compound semiconductor device performance. A large commercial market, however, has allowed the silicon system to mature and produce billion transistor count ICs in high volume. It would be advantageous to combine the merits of both of these technologies in order to enable a new class of high performance ICs. This work demonstrates the wafer scale integration of an advanced 250 nm, 300 GHz fT/fMAX InP DHBT technology with IBMs 130 nm RF-CMOS technology (CMRF8SF). Such integration allows the rapid adoption of more advanced CMOS and InP DHBT technology generations.

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.

A 2D scanner by surface and bulk micromachined vertical comb actuators

We present the design, fabrication, and demonstration of a fully decoupled 2D gimbal scanner with angular vertical comb (AVC) actuators. The device is realized by combining a foundry surface-micromachining process (MUMPs) with a 3-mask deep-reactive-ion- etching (DRIE) post process. Surface-micromachining provides versatile mechanical design and electrical interconnect while bulk micromachining offers flat micromirrors and high-force actuators. The scanner achieves DC mechanical scanning ranges of /spl plusmn/6.2/spl deg/ (at 55 Vdc) and /spl plusmn/4.1/spl deg/ (at 50 Vdc) for the inner and outer gimbals, respectively. The 1-mm mirror has a radius of curvature of 40 cm.

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.

Scanning micromirrors: An overview

An overview of the current state of the art in scanning micromirror technology for switching, imaging, and beam steering applications is presented. The requirements that drive the design and fabrication technology are covered. Electrostatic, electromagnetic, and magnetic actuation techniques are discussed as well as the motivation toward combdrive configurations from parallel plate configurations for large diameter (mm range) scanners. Suitability of surface micromachining, bulk micromachining, and silicon on insulator (SOI) micromachining technology is presented in the context of the length scale and performance for given scanner applications.

A surface and bulk micromachined angular vertical combdrive for scanning micromirrors

We present a high performance scanning micromirror with angular vertical comb actuators realized by combining MUMPs with a 3-mask deep-reactive-ion-etching post process. A DC scan angle of /spl plusmn/4/spl deg/ (mechanical) is achieved at 40 V.