Surface micromachined sensors and actuators
A description of a three-level mechanical polysilicon surface-micromachining technology including a discussion of the advantages of this level of process complexity is presented. This technology is capable of forming mechanical elements ranging from simple cantilevered beams to complex, interconnected, interactive, microactuated micromechanisms. The inclusion of a third deposited layer of mechanical polysilicon greatly extends the degree of complexity available for micromechanism design. Additional features of the Sandia three-level process include the use of Chemical-Mechanical Polishing (CMP) for planarization, and the integration of micromechanics with the Sandia CMOS circuit process. The latter effort includes a CMOS-first, tungsten metallization process to allow the CMOS electronics to withstand high-temperature micromechanical processing. Alternatively, a novel micromechanics-first approach wherein the micromechanical devices are processed first in a well below the surface of the CMOS starting material followed by the standard, aluminum metallization CMOS process is also being pursued. Following the description of the polysilicon surface micromachining are examples of the major sensor and actuator projects based on this technology at the Microelectronics Development Laboratory (MDL) at Sandia National Laboratories. Efforts at the MDL are concentrated in the technology of surface micromachining due to the availability of and compatibility with standard CMOS processes. The primary sensors discussed are a silicon nitride membrane pressure sensor, hot polysilicon filaments for calorimetric gas sensing, and a smart hydrogen sensor. Examples of actuation mechanisms coupled to external devices are also presented. These actuators utilize the three-level process (plus an additional passive level) and employ either surface tension or electrostatic forces.
- Research Organization:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 105673
- Report Number(s):
- SAND-95-1892C; CONF-9510204-1; ON: DE95016733
- Resource Relation:
- Conference: Micro-integrated smart materials and structures conference (MISMSC), Williamsburg, VA (United States), 11-12 Oct 1995; Other Information: PBD: [1995]
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
44 INSTRUMENTATION
INCLUDING NUCLEAR AND PARTICLE DETECTORS
36 MATERIALS SCIENCE
MICROELECTRONIC CIRCUITS
FABRICATION
ACTUATORS
MEASURING INSTRUMENTS
SILICON
SEMICONDUCTOR MATERIALS
POLISHING
SURFACE TENSION
ELECTROSTATIC PROBES
SILICON NITRIDES
PLATINUM