Question

Polysilicon (Top Electrode) Air SI, Bulk Silicon Substrate Figure 1: Cross-section depiction of an electrostatic parallel plate actuator (flexures not shown). Problem 2 a) Design (no fabrication, just a single schematic showing design dimensions) an electrostatic parallel plate actuator made from all polysilicon that has a pull-in voltage of 10 V. The top and bottom electrodes are separated only by air. Given: • Square top plate of 100 um x 100 um • Gap between top and bottom electrode = 2 um • Thickness of top plate and flexures = 2 um Width of flexures = 2 um • Young's Modulus of polysilicon (E) = 169 GPa Number of flexures = 2 b) What is the pull-in distance? c) Using the same design as above, except that there is a combination of an air gap (D = 2 um) and dielectric layer of SizN4 (s = 0.6 um) between the electrodes, as depicted in Figure 1, what is the new pull-in voltage and distance?

Answer 1

(b) Pull in distance If the electrofatie fone is increased by increasing the applich woltage and if that fone as greater than the elastic restoring force the equilibrium is lost and the morable plate will collapse on the fraed ground plate. This phenomenon is known as pull in ..

son 11521310 T utti = 3 Thickness 224m Tro 529 low 2017 - hapblo Top & ballom K plates=24m plov 1 = 100hPa blwtop=2km & boltemplates dielectric layer = 0.6lm

Pull in rottage It is one of the important parameters of meme design the pull in voltage is inversely propational to the actuation Nea. When we increase vo Hage, eventually it will teach a critical point voltage where there is only one solution where the mechanical force is equal to the electrical fone. This is called Pull-in voltage Pull in voltage can be reduced by low spoing constant designs

Thickness 1botimx idolin - atima Capblw = 2tim topf = 100upa bottom plates 2 2 fm- Width of flexure