Micro electromechanical systems thermal switch

Abstract

A Micro Electro-Mechanical Systems (MEMS) thermal switch. The switch includes a FET having a source and drain in a substrate and a beam isolated from the substrate, wherein the beam is a monolithic beam. The beam is positioned over the source and the drain and spaced by a predefined gap. When the thermal set point is reached, the beam moves to electrically connect the source to the drain.

1 . A thermal switch comprising: 
 a FET having a source and drain in a substrate; and    a beam isolated from the substrate and positioned over the source and the drain and spaced by a predefined gap, wherein the beam comprises a monolithic beam.    
     
     
         2 . The switch of  claim 1 , wherein the beam is a metal beam having a thermal set point, when the thermal set point is reached, the metal beam electrically connects the source to the drain.  
     
     
         3 . The switch of  claim 2 , further comprising a voltage source for applying a voltage potential to the metal beam.  
     
     
         4 . The switch of  claim 3 , wherein the voltage source is adjusted in order to attain an electrostatic force between the metal beam and the substrate, thereby adjusting one or more of a thermal set point for the switch or hysteresis of the switch.  
     
     
         5 . The switch of  claim 1 , wherein the beam is arched concave relative the source and the drain.  
     
     
         6 . The switch of  claim 1 , wherein the beam is arched convex relative to the source and the drain.  
     
     
         7 . The switch of  claim 1 , wherein the beam is an h-beam.  
     
     
         8 . A method of fabricating a thermal switch, comprising: 
 providing a silicon substrate;    applying a photoresist;    masking the photoresist according to a source and drain mask;    etching the photoresist according to the photoresist mask;    implanting at least one of N-type or P-type doped material into the substrate;    removing the photoresist;    applying an insulating layer;    masking the insulating layer according to a predefined insulating mask;    etching the insulating layer according to the insulating mask;    applying a sacrificial layer;    masking the sacrificial layer according to a predefined sacrificial layer mask;    etching the sacrificial layer based on the applied sacrificial layer mask;    applying a beam material;    masking the beam material according to a predefined beam mask;    etching the beam material based on the beam mask; and    removing the sacrificial layer.    
     
     
         9 . A thermal switch comprising: 
 a substrate having a source and a drain separated by a predefined gap; and    a connection means isolated from the substrate and positioned over the source and the drain for allowing current between the source and drain at a predefined temperature.    
     
     
         10 . The switch of  claim 9 , wherein the connection means includes a monolithic metal beam having a thermal set point, when the thermal set point is reached, the metal beam electrically connects the source to the drain.  
     
     
         11 . The switch of  claim 10 , further comprising a voltage means for applying a voltage potential to the metal beam.  
     
     
         12 . The switch of  claim 11 , wherein the applied voltage potential is adjusted in order to attain an electrostatic force between the metal beam and the substrate, thereby adjusting one or more of a thermal set point for the switch or hysterisis of the switch.  
     
     
         13 . The switch of  claim 9 , wherein the beam is arched concave relative the source and the drain.  
     
     
         14 . The switch of  claim 9 , wherein the beam is arched convex relative to the source and the drain.  
     
     
         15 . The switch of  claim 9 , wherein the beam is an h-beam.