MICRO-POSTS HAVING IMPROVED UNIFORMITY AND A METHOD OF MANUFACTURE THEREOF
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.
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.