Micro machined polymer beam structure method and resulting device for spring applications

Abstract

An integrated composite beam structure. The structure has a substrate, which includes a surface and a thickness defined underlying the surface. The substrate is composed of a first material. A thickness of polymer based material includes a first portion, a length, and a second portion. The second is coupled to a portion of the substrate. The length is defined between the first portion and the second portion. The structure also has a spring constant (K) of less than a predetermined amount (e.g., 10 N/m, 1 N/m) characterizing the length of the polymer based beam structure. The first portion is capable of moving in a first direction characterized by the spring constant upon application of an externally applied force and is substantially fixed in a second direction, which is normal to the first direction. The second end is capable of returning to a predetermined state when the externally applied force has been removed. The second portion includes a selected geometric configuration to secure the second portion to the portion of the substrate.

What is claimed is:  
     
         1 . A method for fabricating integrated polymer based structures, the method comprising: 
 providing a substrate, the substrate comprising a surface and a thickness defined underlying the surface, the substrate being composed of a first material;    forming a recessed region patterned on a portion of the surface of the substrate, the recessed region having a width and a depth characterizing an internal surface portion of the recessed region, the width being defined by a section along a plane that is parallel to the surface of the substrate, the depth being defined by a section from a lower surface region of the recessed region to the portion of the surface of the substrate, the recessed region further comprising a length, the length including a first portion and a second portion;    forming a thickness of polymer based material overlying a portion of the internal surface portion including the lower portion of the recessed region, the polymer based material conforming to the portion of the internal surface portion and the lower portion of the polymer based material, the polymer based material also overlying the first portion and the second portion of the length of the recessed region; and    removing a portion of the substrate within a vicinity of the recessed region to release the first portion of the polymer based material to facilitate a removal of the first portion of the polymer based material from the portion of the substrate while maintaining the second portion of the polymer based material coupled to the portion of the substrate.    
     
     
         2 . The method of  claim 1  wherein the substrate comprises a silicon material.  
     
     
         3 . The method of  claim 1  wherein the substrate is a silicon substrate or a glass substrate.  
     
     
         4 . The method of  claim 1  wherein the width and depth define an aspect ratio, the aspect ratio being greater than two.  
     
     
         5 . The method of  claim 1  wherein the removing of the portion of the substrate from the first portion of the polymer based material comprises an etching process, the etching process selectively removes the portion of the substrate from the portion of the polymer based material.  
     
     
         6 . The method of  claim 1  wherein the polymer based material is parylene.  
     
     
         7 . The method of  claim 1  wherein the polymer based material is selected from polyimide, PEEK, or polycarbonate.  
     
     
         8 . The method of  claim 1  wherein the recessed region is a trench structure.  
     
     
         9 . The method of  claim 1  wherein the released first portion of the polymer based material forms a beam structure, the beam structure extending from the first portion of the polymer based material.  
     
     
         10 . The method of  claim 1  wherein the width is less than 100 microns and the depth is greater than 10 microns.  
     
     
         11 . The method of  claim 1  further comprising forming a texture within the internal surface portion and then forming the thickness of polymer based material, the texture facilitating attachment of the polymer based material to the substrate.  
     
     
         12 . The method of  claim 11  wherein the texture comprises a plurality of pores spatially disposed on the internal surface portion.  
     
     
         13 . The method of  claim 1  wherein the plurality of pores forms a roughened region on the internal surface portion.  
     
     
         14 . The method of  claim 1  further comprising completely removing the first portion of the polymer based material from the portion of the substrate.  
     
     
         15 . The method of  claim 1  wherein the polymer based material comprises a parylene, the parylene being provided by chemical vapor deposition.  
     
     
         16 . The method of  claim 1  wherein the polymer based material is a homogenous structure.  
     
     
         17 . The method of  claim 1  wherein the released first portion of the polymer based material is characterized by a spring constant (K) of less than 10 N/m.  
     
     
         18 . The method of  claim 1  wherein the released first portion of the polymer based material is characterized by a spring constant (K) of less than 10 N/m and wherein the released first portion of the polymer based beam structure is configured as a cantilever style spring structure.  
     
     
         19 . The method of  claim 1  wherein the released first portion of the polymer based material is characterized by a spring constant (K) of less than 10 N/m and wherein the released first portion of the polymer based beam structure is configured as a folded spring structure.  
     
     
         20 . The method of  claim 1:   wherein the substrate comprises a silicon bearing material;    wherein the forming of the recessed region includes patterning and etching the portion of the surface of the substrate;    wherein the forming of the thickness of polymer based material is provided by chemical vapor deposition; and    wherein the removing of the portion of the substrate within a vicinity of the recessed region comprises patterning a portion of the substrate and etching the patterned portion to release the first portion of the polymer based material.    
     
     
         21 . The method of  claim 1  wherein the second portion of the polymer based material is integrated into the substrate.  
     
     
         22 . Apparatus for sensing spatial movement within a predetermined sensitivity range, the apparatus comprising: 
 a rigid substrate structure;    a polymer based beam structure including a first end and a second end, the first end being formed being opposite of the second end and having a length defined therebetween, the first end being coupled to a portion of the substrate structure, the polymer based beam structure having a predetermined width and a predetermined thickness; the second end extending from the rigid substrate structure;    a spring constant (K) of less than 10 N/m characterizing the polymer based beam structure;    whereupon the second end being capable of moving in a first direction characterized by the spring constant upon application of an externally applied force and is substantially fixed in a second direction, the first direction being normal to the second direction; and    whereupon the second end being capable of returning to a predetermined state when the externally applied force has been removed.    
     
     
         23 . Apparatus of  claim 23  wherein the spring constant is less than 1×10−3 N/m.  
     
     
         24 . Apparatus of  claim 23  wherein the spring constant is less than 1×10−4 N/m.  
     
     
         25 . Apparatus of  claim 23  wherein the first direction is a z-direction, the z-direction being normal to a straight line defined between the first end and the second end of the polymer based beam structure.  
     
     
         26 . Apparatus of  claim 23  wherein the first direction is a z-direction, the z-direction being normal to a straight line defined between the first end and the second end of the polymer based beam structure; and wherein the polymer based beam structure is configured as a cantilever style spring structure.  
     
     
         27 . Apparatus of  claim 23  wherein the first direction is an x-direction, the x-direction being parallel to a straight line defined between the first end and the second end of the polymer based beam structure.  
     
     
         28 . Apparatus of  claim 23  wherein the first direction is an x-direction, the x-direction being parallel to a straight line defined between the first end and the second end of the polymer based beam structure; and wherein the polymer based beam structure is configured as a folded spring structure.  
     
     
         29 . Apparatus of  claim 23  wherein the predetermined width and the predetermined thickness define an aspect ratio.  
     
     
         30 . Apparatus of  claim 30  wherein the aspect ratio is greater than two.  
     
     
         31 . Apparatus of  claim 30  wherein the aspect ratio is greater than three.  
     
     
         32 . Apparatus of  claim 23  wherein the rigid substrate structure is a silicon substrate.  
     
     
         33 . Apparatus of  claim 23  wherein the rigid substrate structure is a silicon substrate or a glass substrate.  
     
     
         34 . Apparatus of  claim 23  wherein the polymer based material is parylene.  
     
     
         35 . Apparatus of  claim 23  wherein the polymer based material is selected from polyimide, polycarbonate, or PEEK.  
     
     
         36 . Apparatus of  claim 23  further comprising a textured region between the rigid substrate structure and the first end of the polymer based material, the textured region facilitating adhesion between the first end and the rigid substrate structure.  
     
     
         37 . Apparatus of  claim 37  wherein the texture comprises a plurality of pores spatially disposed on a portion of the rigid substrate structure.  
     
     
         38 . Apparatus of  claim 38  wherein the plurality of pores forms a roughened region to enhance adhesion between the first end and the rigid substrate structure.  
     
     
         39 . An integrated composite beam structure, the beam structure comprising: 
 a substrate, the substrate comprising a surface and a thickness defined underlying the surface, the substrate being composed of a first material;    a thickness of polymer based material including a first portion, a length, and a second portion, the second portion being coupled to a portion of the substrate, the length being defined between the first portion and the second portion;    a spring constant (K) of less than 10 N/m characterizing the length of the polymer based beam structure, the first portion being capable of moving in a first direction characterized by the spring constant upon application of an externally applied force and is substantially fixed in a second direction, the first direction being normal to the second direction, the first portion being capable of returning to a predetermined state when the externally applied force has been removed; and    wherein the second portion comprising a selected geometric configuration to secure the second portion to the portion of the substrate.    
     
     
         40 . The structure of  claim 40  wherein the selected geometric configuration is triangular in shape, the selected geometric configuration being formed within a recessed region in the portion of the substrate, the recessed region having a similar geometric configuration to conform to the selected geometric configuration of the second portion of the thickness of polymer based material.  
     
     
         41 . The structure of  claim 40  wherein the selected geometric configuration is annular in shape, the selected geometric configuration being formed within a recessed region in the portion of the substrate, the recessed region having a similar geometric configuration to conform to the selected geometric configuration of the second portion of the thickness of polymer based material.  
     
     
         42 . The structure of  claim 40  wherein the selected geometric configuration is molded into a recessed region in the portion of the substrate, the recessed region having a similar geometric configuration to conform to the selected geometric configuration of the second portion of the thickness of polymer based material.  
     
     
         43 . A method for fabricating polymer based structures for manufacture of MEMS elements, the method comprising: 
 providing a substrate, the substrate comprising a surface and a thickness defined underlying the surface, the substrate being composed of a first material;    forming a recessed region patterned on a portion of the surface of the substrate, the recessed region having a width and a depth characterizing an internal surface portion of the recessed region, the width being defined by a section along a plane that is parallel to the surface of the substrate, the depth being defined by a section from a lower surface region of the recessed region to the portion of the surface of the substrate;    forming a thickness of polymer based material overlying a portion of the internal surface portion including the lower portion of the recessed region, the polymer based material conforming to the portion of the internal surface portion and the lower portion of the polymer based material; and    removing a portion of the substrate within a vicinity of the recessed region to release a portion of the polymer based material to facilitate a removal of the portion of the polymer based material from the portion of the substrate;    wherein the portion of the polymer based material that has been removed forms a molded polymer based structure.    
     
     
         44 . The method of  claim 44  wherein the substrate comprises a silicon material.  
     
     
         45 . The method of  claim 44  wherein the substrate is a silicon substrate or a glass substrate.  
     
     
         46 . The method of  claim 44  wherein the width and depth define an aspect ratio, the aspect ratio being greater than two.  
     
     
         47 . The method of  claim 44  wherein the removing comprises an etching process, the etching process selectively removes the portion of the substrate from the portion of the polymer based material.  
     
     
         48 . The method of  claim 44  wherein the polymer based material is parylene.  
     
     
         49 . The method of  claim 44  wherein the polymer based material is selected from polyimide, polycarbonate, or PEEK.  
     
     
         50 . The method of  claim 44  wherein the recessed region is a trench structure.  
     
     
         51 . The method of  claim 44  wherein the released portion of the polymer based material forms a beam structure.  
     
     
         52 . The method of  claim 44  wherein the width is less than 100 microns and the depth is greater than 10 microns.  
     
     
         53 . The method of  claim 44  further comprising forming a texture within the internal surface portion and then forming the thickness of polymer based material.  
     
     
         54 . The method of  claim 54  wherein the texture comprises a plurality of pores spatially disposed on the internal surface portion.  
     
     
         55 . The method of  claim 44  wherein the plurality of pores forms a roughened region on the internal surface portion.  
     
     
         56 . The method of  claim 44  further comprising removing the portion of the polymer based material from the portion of the substrate.  
     
     
         57 . The method of  claim 44  wherein the polymer based material comprises a parylene, the parylene being provided by chemical vapor deposition.