Structure for decreasing minimum feature size in an integrated circuit

Abstract

A single, controlled etch step can be used to form a sharp tip feature along a sidewall of an etch feature. An etch process is used that is selective to a layer of tip material relative to the substrate upon which the layer is deposited. A lag can be created in the etch, such that the etch rate is slower near the sidewall. The sharp tip feature is formed from the same layer of material used to create the etch feature. The sharp tip feature can be used to decrease the minimum critical dimension of an etch process, such as may be due to the minimum resolution of a photolithographic process. The novel tip feature also can be used for other applications, such as to create a microaperture for a photosensitive device, or to create a micromold that can be used to form objects such as microlenses.

1 . An apparatus for decreasing minimum feature size in circuit design, comprising: 
 a substrate of a first material;    a layer of a second material adjacent the substrate; and    an etch feature in the layer of a second material, the etch feature having sidewalls substantially perpendicular to the substrate and a sharp tip feature adjacent the sidewalls and substrate, such that the dimension of a mask feature defined by the sharp tip feature is smaller than the minimum dimension of the photolithographic process used to create the etch feature.    
   
   
       2 . An apparatus as in  claim 1 , and further comprising: 
 a layer of photoresist material over the layer of a second material.    
   
   
       3 . An apparatus as in  claim 2 , and further comprising: 
 a photolithography device for transferring a circuit pattern to the layer of photoresist material, the circuit pattern containing a design feature corresponding to the etch feature.    
   
   
       4 . An apparatus as in  claim 1 , and further comprising: 
 an etch reactor for etching the layer of a second material.    
   
   
       5 . A micro-aperture for a photosensitive device, comprising: 
 a substrate of a first material capable of containing a photosensitive device;    a layer of a second material adjacent the substrate; and    an opening in the layer of a second material, the opening having sidewalls substantially perpendicular to the substrate and a sharp tip feature adjacent the sidewalls, such that the sharp tip feature forms an aperture for any photosensitive device contained in the substrate.    
   
   
       6 . A micro-aperture as in  claim 5 , and further comprising: 
 a photosensitive device contained by the substrate.    
   
   
       7 . A micro-aperture as in  claim 5 , and wherein: 
 said opening in the layer of a second material is substantially circular.    
   
   
       8 . A micro-aperture as in  claim 5 , and further comprising: 
 a masking layer on the layer of a second material for controlling the shape and dimension of the opening.