Nickel-filled Hexsil Thermally Actuated Tweezers

Abstract

We report the first demonstration of a molded micromachine consisting of a high adpect-ratio CVD polysilicon shell filled with electroless nickel for the conductive regions, in situ P-doped polysilicon for the resistive regions, and undoped polysilicon for the insulating regions of the machine. One mask defines all regions simultaneously on the basis of mold trench width. Electroless Ni enables high current-canying capacity with minimal power dissipation. Electroless plating proceeds conformally over the entire polysilicon surface so that a deep trench can be filled by deposits growing from the sidewalls toward the middle of the trench, a distance of only a few pm. In these first prototypes, tip displacement of 25 pm was observed with a current of 300 mA at 3 V. Wire actuated, normally closed, and normally open, tweezers with 200 pm tip motion are also demonstrated. INTRODUCTIONThe essence of this work is the use of trench width in the mold to control beam composition in the structure.

Micro- and Nano-assembly and Manipulation Techniques for MEMS

“…It is not surprising, therefore, that MEMS technology has also been successfully applied to mechanical gripping. Micro-mechanical tweezers have been developed using polycrystalline silicon (Kim et al, 1990;Keller and Howe, 1995), shape memory alloy (SMA) (Kohl et al, 2002;Bellouard et al, 1998;Hesselbach et al, 1997) Figure 4. Pick up and release using van der Waals force-based gripper [left, (Miyazaki and Zato, 1996)] and using gas expansion/contraction [right, Arai and Fukuda (1997)].…”

Surface micromachining for microelectromechanical systems

“…A characteristic feature of this molding process is that large-area structures are built from a rigid network of interconnected segments, the width and depth of which are defined by the groove dimensions. This molding concept can be applied to other materials that can be deposited conformally, such as electroless nickel [125], and LPCVD films such as silicon nitride and tungsten. Composite structures are possible if the outside layer can withstand the sacrificial etching process.…”

Recent Advances in Surface Micromachining

“…This molding concept can be applied to other materials that can be deposited conformally, such as electroless nickel [74], and LPCVD films such as silicon nitride and tungsten. Composite structures are possible if the outside layer can withstand the sacrificial etching process.…”