The following are the cell names and cell descriptions of sample
layouts designed at NIST for micromechanical designs.

  1.  open-80x80

      A MEMS test structure to check the progress of the EDP etchant
      on an intended 80 um x 80 um cavity.  This design consists of a 
      single open tile.

  2.  open-oxide-80x80

      An additional MEMS test structure to check the progress of
      the etchant on an intended 80 um x 80 um cavity with a
      trampoline-like suspended oxide.  This design consists of 
      four trapezoidal-shaped open tiles brought together in close 
      vicinity such that the four cavities merge in the 
      post-processing etch step creating one large 80 um x 80 um 
      cavity with a suspended layer of oxide (see fig. 1).

  3.  thermal-converter

      A polysilicon (poly1) heater with a metal1/poly1 thermopile 
      used as an ac power sensor.

  4.  thermal-actuator

      A cantilever structure consisting of poly1 with metal1 on 
      top.  These are connected at the end of the `diving board'
      and, when heated, the diving board bends upward due to the
      different thermal expansion coefficients of poly1 and
      metal1.

  5.  pixel-80x80

      A heating element with an 80 um x 80 um cavity.  The heating 
      element is made of meandering polysilicon (poly1) and is
      suspended over top of the cavity with its encompassing oxide
      after the anisotropic etch.

  6.  pixel-160x160

      Similar to the above structure but with a 160 um x 160 um 
      cavity.

  7.  micro-hot-plate

      The microhotplate design consists of:
      a.  A meandering polysilicon (poly1) heating element with
          two external connections.
      b.  An aluminum (metal1) plate with four external connections
          over top of the polysilicon (poly1) heating element.
          There is an oxide separating the poly1 and metal1.  
          The heat is uniformly distributed across this metal1 
          plate with the metal1 resistance changing linearly with 
          temperature.  The metal1 sheet resistance at the 
          various temperatures can be obtained with a 
          van der Pauw measurement.

  8.  gas-sensor

      The gas sensor design consists of the microhotplate design
      above with the addition of two layers:

      a.  Four metal2 pads placed in the corners of the metal1
          microhotplate (but not in contact with it). There 
          are four external metal2 connections.
      b.  Overglass openings centered on top of the metal2 pads.
          The metal2 pads and overglass openings allow a substance 
          (e.g., tin oxide and palladium) to be placed on top of the
          whole pixel.  When heated, the resistance of the substance
          changes in the presense of certain gases.  The metal2 acts
          as a van der Pauw sheet resistor so the resistance change 
          can be measured.  This application of the microhotplate is 
          called a gas sensor.  (NIST has a patent pending on this
          gas sensor design.)