Micro-posts having improved uniformity and a method of manufacture thereof

Abstract

As discussed herein, there is presented an apparatus comprising micro-posts. The apparatus includes a substrate having a planar surface, a plurality of micro-posts located on the planar surface, wherein each micro-post has a base portion on the planar surface and a post portion located on a top surface of the corresponding base portion, and wherein side surfaces of the base portions intersect the planar surface at oblique angles.

What is claimed is: 
     
         1 . A method, comprising:
 performing a dry etch to form a post portion of a micro-post in a trench on a surface of a substrate;   performing a wet etch to remove a layer from said substrate such that the post portion is located on a base portion and the base portion is located on a planar surface of the substrate, the base portion having side surfaces that intercept the top planar surface obliquely.   
     
     
         2 . The method of  claim 1 , further comprising:
 forming a mask around the post portion and a laterally adjacent portion of the original surface prior to performing the wet etch.   
     
     
         3 . The method of  claim 2 , wherein the performing a wet etch removes portion of the substrate below the mask. 
     
     
         4 . The method of  claim 1  wherein:
 performing the dry etch includes forming a trench in the substrate and to a depth within the substrate; 
 forming a mask layer on the substrate, and the surfaces of the post, and the trench; 
 removing the mask from the substrate such that a portion of the mask remains on the substrate adjacent the trench, and on the surfaces of the trench and the post; and 
 using an anisotropic etch to remove the substrate, including removing the substrate located under the mask to the depth of the trench. 
 
     
     
         5 . The method of  claim 1 , wherein performing the dry etch includes using a plasma etch and the trench is formed to a depth of at least 1 micron. 
     
     
         6 . The method of  claim 4 , wherein forming the mask includes oxidizing surfaces of the substrate, the trench and the post to form an oxide mask thereon. 
     
     
         7 . The method of  claim 4 , wherein forming the mask includes depositing a silicon nitride film on the substrate, the trench and the post. 
     
     
         8 . The method of  claim 1 , wherein performing a wet etch includes using an anisotropic etch of an aqueous solution of potassium hydroxide (KOH). 
     
     
         9 . The method of  claim 1 , wherein the substrate is a silicon substrate that presents a <100> crystal orientation at the surface. 
     
     
         10 . The method of  claim 9 , wherein performing a wet etch includes using an anisotropic etch of a solution of potassium hydroxide (KOH). 
     
     
         11 . The method of  claim 9 , wherein the KOH comprises from about 20% to about 45% by weight of the aqueous solution and the etch is conducted at a temperature that ranges from about 30° C. to about 80° C. 
     
     
         12 . The method of  claim 1 , wherein the substrate is a silicon substrate that presents a <110> crystal orientation at the surface. 
     
     
         13 . The method of  claim 12 , wherein performing a wet etch includes using an anisotropic etch of an aqueous solution of potassium hydroxide (KOH). 
     
     
         14 . The method of  claim 1 , wherein performing a wet etch includes using an anisotropic etch of an aqueous solution of tetramethylammonium hydroxide (TMAH). 
     
     
         15 . The method of  claim 1 , wherein performing the dry etch to form a trench includes forming the trench to a depth ranging from about 2 microns to about 100 microns. 
     
     
         16 . The method of  claim 1 , wherein a ratio of a height of each micro-post to the width of each base portion is at least 2:1.