Elastic bump stops for mems devices

Abstract

A MEMS device includes at least one proof mass, the at least one proof mass is capable of moving to contact at least one target structure. The MEMS device further includes at least one elastic bump stop coupled to the proof mass and situated at a first distance from the target structure. The MEMS device additionally includes at least one secondary bump stop situated at a second distance from the target structure, wherein the second distance is greater than the first distance, and further wherein the at least one elastic bump stop moves to reduce the first distance when a shock is applied.

What is claimed is: 
     
         1 . A MEMS device comprising:
 at least one proof mass capable of moving relative to a substrate;   a first contact surface coupled to the at least one proof mass;   a second contact surface coupled to the at least one proof mass;   a first target surface facing the first contact surface and separated from the first contact surface by a first distance;   a second target surface facing the second contact surface and separated from the second contact surface by a second distance; and   the first contact surface is coupled to the proof mass by a flexible element or the first target surface is coupled to the flexible element,   wherein the at least one proof mass is coupled to the substrate by a spring,   wherein when the at least one proof mass moves, the first contact surface moves to reduce the first distance until the first contact surface contacts the first target surface,   wherein when the first contact surface and the first target surface are in contact and the at least one proof mass moves, at least one flexible element flexes and the second contact surface moves to reduce the second distance until the second contact surface contacts the second target surface.   
     
     
         2 . The MEMS device of  claim 1 , wherein the at least one proof mass moves at a plane substantially parallel to the substrate. 
     
     
         3 . The MEMS device of  claim 1 , wherein the at least one proof mass moves out of a plane parallel to the substrate. 
     
     
         4 . The MEMS device of  claim 1 , wherein the flexible element is a torsional spring. 
     
     
         5 . The MEMS device of  claim 1 , wherein the first target surface is stationary with respect to the substrate. 
     
     
         6 . The MEMS device of  claim 5 , wherein the flexible element is coupled to the at least one proof mass. 
     
     
         7 . The MEMS device of  claim 1 , wherein the flexible element is a clamped-clamped beam. 
     
     
         8 . The MEMS device of  claim 7 , further comprising a first structure coupled to the first target surface, thereby extending a portion of the first target surface towards the at least one proof mass. 
     
     
         9 . The MEMS device of  claim 7 , further comprising a first structure coupled to the first contact surface thereby extending a portion of the first contact surface towards the at least one proof mass 
     
     
         10 . The MEMS device of  claim 9 , further comprising a second structure coupled to the second target surface or the second contact surface. 
     
     
         11 . The MEMS device of  claim 10 , wherein the second structure is a secondary bump stop. 
     
     
         12 . The MEMS device of  claim 10 , wherein the second structure is less flexible than the at least one flexible element. 
     
     
         13 . The MEMS device of  claim 1 , wherein the second target surface is stationary with respect to the substrate. 
     
     
         14 . The MEMS device of  claim 1 , wherein the first contact surface is smaller than the second contact surface. 
     
     
         15 . The MEMS device of  claim 1 , where in the MEMS device is a gyroscope or an accelerometer. 
     
     
         16 . The MEMS device of  claim 1 , wherein the at least one proof mass moves translationally. 
     
     
         17 . The MEMS device of  claim 1 , wherein the at least one proof mass moves rotationally. 
     
     
         18 . The MEMS device of  claim 1 , further comprising a structure coupled to the at least one proof mass by a second flexible element,
 wherein the first contact surface is formed on a the first surface of the structure,   wherein the second target surface is formed on a second surface of the structure,   wherein the second contact surface is formed on the at least one proof mass.   
     
     
         19 . The MEMS device of  claim 18 , wherein the second flexible element is a cantilever beam.