CATALYTIC ETCH WITH MAGNETIC DIRECTION CONTROL
A material can be locally etched with arbitrary changes in the direction of the etch. A ferromagnetic-material-including catalytic particle is employed to etch the material. A wet etch chemical or a plasma condition can be employed in conjunction with the ferromagnetic-material-including catalytic particle to etch a material through a catalytic reaction between the catalytic particle and the material. During a catalytic etch process, a magnetic field is applied to the ferromagnetic-material-including catalytic particle to direct the movement of the particle to any direction, which is chosen so as to form a contiguous cavity having at least two cavity portions having different directions. The direction of the magnetic field can be controlled so as to form the contiguous cavity in a preplanned pattern, and each segment of the contiguous cavity can extend along an arbitrary direction.
1 . A patterned structure comprising:
a substrate having a surface; and
a plurality of contiguous cavities extending from said surface into said substrate, wherein each of said plurality of contiguous cavities comprises at least a first cavity portion extending along a first direction and a second cavity portion extending along a second direction, wherein said first direction and said second direction are different.
2 . The patterned structure of claim 1 , wherein said first cavity portion is a straight portion having a single propagation direction, and said second cavity portion is a curved portion having a propagation direction that changes continuously.
3 . The patterned structure of claim 1 , wherein each of said plurality of contiguous cavities has a substantially same geometrical shape.
4 . The patterned structure of claim 1 , wherein each of said plurality of contiguous cavities further comprises a third cavity portion extending along a third direction, wherein said first direction, said second direction, and said third direction are not within a same two-dimensional plane.
5 . The patterned structure of claim 1 , wherein an angle between said first direction and said second direction is at least 90 degrees.
6 . The patterned structure of claim 1 , wherein said substrate comprises a semiconductor material including silicon, a silicon-germanium alloy, a silicon-carbon alloy, a silicon-germanium-carbon alloy, or germanium.
7 . The patterned structure of claim 1 , further comprising a material layer including a plurality of holes therein and covering said surface and containing a non-semiconductor material, wherein one end of each of said plurality of contiguous cavities coincides with one end of said plurality of holes.
8 . The patterned structure of claim 7 , wherein said non-semiconductor material comprises silicon oxide, silicon nitride, a dielectric metal oxide material, a dielectric metal nitride material, or combinations thereof.
9 . The patterned structure of claim 1 , wherein a ferromagnetic-material-including catalytic particle is embedded within an end of each of said plurality of contiguous cavities.
10 . The patterned structure of claim 9 , wherein said ferromagnetic-material-including catalytic particle comprises:
a ferromagnetic material core; and
a surface coating over said ferromagnetic material core, said surface coating comprising a catalytic material that functions as a catalyst for a catalytic etch process.
11 . The patterned structure of claim 10 , wherein said ferromagnetic material core comprises iron, cobalt, nickel, dysprosium, gadolinium, chromium oxide, ferrites, gallium manganese arsenide, magnetite, a permalloy, a rare-earth magnet, a samarium-cobalt alloy, suessite, yttrium iron garnet, or a combination thereof.
12 . The patterned structure of claim 9 , wherein said at least one ferromagnetic-material-including catalytic particle consists of a ferromagnetic material that is a catalytic material that functions as a catalyst for a catalytic etch process.
13 . The patterned structure of claim 9 , wherein a catalytic surface of said ferromagnetic-material-including catalytic particle comprises a silver surface, a platinum surface, or a tungsten surface.