79 lines
3.0 KiB
Plaintext
79 lines
3.0 KiB
Plaintext
The following are the cell names and cell descriptions of sample
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layouts designed at NIST for micromechanical designs.
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1. open-80x80
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A MEMS test structure to check the progress of the EDP etchant
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on an intended 80 um x 80 um cavity. This design consists of a
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single open tile.
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2. open-oxide-80x80
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An additional MEMS test structure to check the progress of
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the etchant on an intended 80 um x 80 um cavity with a
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trampoline-like suspended oxide. This design consists of
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four trapezoidal-shaped open tiles brought together in close
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vicinity such that the four cavities merge in the
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post-processing etch step creating one large 80 um x 80 um
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cavity with a suspended layer of oxide (see fig. 1).
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3. thermal-converter
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A polysilicon (poly1) heater with a metal1/poly1 thermopile
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used as an ac power sensor.
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4. thermal-actuator
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A cantilever structure consisting of poly1 with metal1 on
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top. These are connected at the end of the `diving board'
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and, when heated, the diving board bends upward due to the
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different thermal expansion coefficients of poly1 and
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metal1.
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5. pixel-80x80
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A heating element with an 80 um x 80 um cavity. The heating
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element is made of meandering polysilicon (poly1) and is
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suspended over top of the cavity with its encompassing oxide
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after the anisotropic etch.
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6. pixel-160x160
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Similar to the above structure but with a 160 um x 160 um
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cavity.
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7. micro-hot-plate
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The microhotplate design consists of:
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a. A meandering polysilicon (poly1) heating element with
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two external connections.
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b. An aluminum (metal1) plate with four external connections
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over top of the polysilicon (poly1) heating element.
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There is an oxide separating the poly1 and metal1.
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The heat is uniformly distributed across this metal1
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plate with the metal1 resistance changing linearly with
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temperature. The metal1 sheet resistance at the
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various temperatures can be obtained with a
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van der Pauw measurement.
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8. gas-sensor
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The gas sensor design consists of the microhotplate design
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above with the addition of two layers:
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a. Four metal2 pads placed in the corners of the metal1
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microhotplate (but not in contact with it). There
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are four external metal2 connections.
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b. Overglass openings centered on top of the metal2 pads.
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The metal2 pads and overglass openings allow a substance
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(e.g., tin oxide and palladium) to be placed on top of the
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whole pixel. When heated, the resistance of the substance
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changes in the presense of certain gases. The metal2 acts
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as a van der Pauw sheet resistor so the resistance change
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can be measured. This application of the microhotplate is
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called a gas sensor. (NIST has a patent pending on this
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gas sensor design.)
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