Probe for a scanning probe microscope and method of manufacture

Abstract

A probe assembly for an instrument and a method of manufacture includes a substrate and a cantilever having a length independent of typical alignment error during fabrication. In one embodiment, the probe assembly includes a buffer section interposed between the substrate and the cantilever. The cantilever extends from the buffer section and a portion of the buffer section extends beyond an edge of the substrate. The portion of the buffer section is more stiff than the cantilever. The corresponding method of producing the probe assembly facilitates batch fabrication without compromising probe performance.

1 . A probe assembly for a surface analysis instrument, the probe assembly comprising: 
 a substrate defining a base of the probe assembly;    a cantilever extending from the base and having a distal end;    wherein a length of said cantilever is independent of alignment error during probe fabrication.    
     
     
         2 . The probe assembly of  claim 1 , further comprising a buffer section interposed between said substrate and said cantilever, said cantilever extending from said buffer section.  
     
     
         3 . The probe assembly of  claim 2 , wherein a portion of said buffer section extends beyond an edge of said substrate, and wherein said portion is more stiff than said cantilever, and wherein said buffer section is made of one of silicon nitride and silicon oxide.  
     
     
         4 . The probe assembly of  claim 3 , wherein said buffer section is at least two times thicker than said cantilever.  
     
     
         5 . The probe assembly of  claim 2 , wherein said buffer section is made of the same material as said cantilever.  
     
     
         6 . The probe assembly of  claim 2 , wherein a stiffness of said buffer section is in at least about an order of magnitude greater than a stiffness of said cantilever.  
     
     
         7 . The probe assembly of  claim 6 , wherein a stiffness of said buffer section is in a range of about 10 to 50 N/m.  
     
     
         8 . The probe assembly of  claim 2 , wherein said cantilever has a thickness less than about 1000 nm.  
     
     
         9 . The probe assembly of  claim 8 , wherein said cantilever has a thickness less than about 100 nm.  
     
     
         10 . The probe assembly of  claim 3 , wherein said portion of said buffer section is at least about 10 times as stiff as said cantilever.  
     
     
         11 . The probe assembly of  claim 1 , wherein said substrate is one of silicon and glass, and wherein an operational resonant frequency of said cantilever is in a range of about 300 to 1000 kHz.  
     
     
         12 . The probe assembly of  claim 1 , wherein a length of said cantilever is less than about 50 microns.  
     
     
         13 . The probe assembly of  claim 12 , wherein the length is less than about 10 microns.  
     
     
         14 . A method of fabricating a probe assembly for a surface analysis instrument, the method comprising: 
 forming a probe of the probe assembly, the probe including a cantilever; and    wherein a length of the cantilever is independent of an alignment error associated with said forming step.    
     
     
         15 . The method of  claim 14 , wherein said forming step includes forming at least a portion of the probe assembly on a substrate and dicing the substrate to release the probe assembly, wherein said dicing step is responsible for the alignment error.  
     
     
         16 . The method of  claim 15 , further comprising, 
 producing a buffer section; and    wherein said forming step includes disposing a layer of a cantilever material on the buffer section such that the cantilever extends from the buffer section, and wherein said dicing step is performed so that at least a portion of the buffer section extends beyond an edge of the substrate.    
     
     
         17 . The method of  claim 16 , wherein the buffer section is a layer of material having a thickness substantially greater than a thickness of the cantilever.  
     
     
         18 . The method of  claim 17 , wherein the layer of material is silicon oxide.  
     
     
         19 . The method of  claim 16 , wherein a stiffness of said buffer section is at least an order of magnitude greater than a stiffness of said cantilever.  
     
     
         20 . The method of  claim 16 , wherein said cantilever is less than 100 nm thick.  
     
     
         21 . The method of  claim 16 , wherein a length of the cantilever is less than 20 microns.  
     
     
         22 . The method of  claim 21 , wherein a length of the cantilever is less than 10 microns.  
     
     
         23 . The method of  claim 18 , wherein the cantilever material is silicon nitride, and wherein the substrate is one of silicon and glass.  
     
     
         24 . The method of  claim 23 , wherein said forming step includes depositing the silicon nitride on the substrate, and the substrate is a sacrificial silicon wafer.  
     
     
         25 . The method of  claim 14 , wherein said forming step includes performing an offset alignment technique to define the length of the cantilever.  
     
     
         26 . The method of  claim 25 , wherein said performing step further includes, 
 providing a sacrificial wafer,    shaping a tip in the wafer, then    depositing a cantilever material on the wafer, wherein said coupling step includes bonding the substrate to the cantilever material;    removing the wafer; and    applying a layer of a material to the substrate opposite the cantilever material.    
     
     
         27 . The method of  claim 26 , wherein said shaping step includes using a nanodot and plane overetch technique.  
     
     
         28 . The method of  claim 26 , wherein said removing step includes etching the wafer, and wherein said bonding step includes fusion wafer bonding.  
     
     
         29 . The method of  claim 26 , wherein the cantilever material and the material layer are silicon nitride.  
     
     
         30 . The method of  claim 26 , wherein said performing step includes patterning the probe, etching the cantilever material and the material layer, and then etching the substrate.  
     
     
         31 . The method of  claim 28 , wherein said etching the substrate step includes a KOH etch to the ( 111 ) plane.  
     
     
         32 . The method of  claim 26 , wherein the probe has a length less than 20 microns.