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Proceedings Paper

Design and simulation of thermal actuators for STM applications in a standard CMOS process
Author(s): Steven Eagle; Hasnain Lakdawala; Gary K. Fedder
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Paper Abstract

In this paper a design of thermal actuators for out-of-plane displacements for parallel Scanning Tunneling Microscope (STM) applications in a standard 0.5 micrometers 3-metal CMOS process is presented. Micromachined STM tips have potential applications in data storage, lithography and high sensitivity microsensors. Standard CMOS process allows for low cost integration of on chip electronics with microstructures. The STM tip actuator consists of a multilayer micromachined beam constructed of various combinations of metal and oxide layers of the CMOS process. Polysilicon is used to heat the multimorph to achieve tip deflection. The tip deflections are a function of the beam design parameters, such as different combinations of metal and oxide layers, and beam length. Analytical results for heat distribution within the multimorph structure are presented along with thermo-mechanical finite element simulations based on previously obtained material properties for the process and experimental results. The validation of this design methodology allows design of STM actuators with desired specifications. The maximum out-of-plane displacements for the 115 micrometers long multimorph actuators with different metal and oxide layer combinations range from 0.5 to 10.0 micrometers for an input power of 10 mW. Spurious in- plane motions of thermal actuators due to mask misalignments in the standard CMOS process are limited by design. The out of plane curling of the actuators varies from 1.65 to 15.75 micrometers depending on beam composition. The maximum power dissipation for all actuators was less than 25 mW.

Paper Details

Date Published: 3 September 1999
PDF: 8 pages
Proc. SPIE 3875, Materials and Device Characterization in Micromachining II, (3 September 1999); doi: 10.1117/12.360467
Show Author Affiliations
Steven Eagle, Carnegie Mellon Univ. (United States)
Hasnain Lakdawala, Carnegie Mellon Univ. (United States)
Gary K. Fedder, Carnegie Mellon Univ. (United States)


Published in SPIE Proceedings Vol. 3875:
Materials and Device Characterization in Micromachining II
Yuli Vladimirsky; Craig R. Friedrich, Editor(s)

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