METHOD FOR ACHIEVING STICTION-FREE HIGH-ASPECT-RATIO MICROSTRUCTURES AFTER WET CHEMICAL PROCESSING
A method for wet chemical processing of high-aspect-ratio microstructures and exiting the wet chemical processing while avoiding stiction between the high-aspect-ratio microstructures is provided. The method includes providing a substrate containing etched microstructures, removing etch residue from the substrate using wet chemical processing, rinsing the substrate with an aqueous hydrogen fluoride solution after the wet chemical processing, and drying the substrate using an inert gas.
1 . A substrate processing method, comprising:
providing a substrate containing etched microstructures;
removing etch residue from the etched microstructures using wet chemical processing;
rinsing the substrate with an aqueous hydrogen fluoride solution after the wet chemical processing; and
drying the substrate using an inert gas to remove any water from the etched microstructures.
2 . The method of claim 1 , wherein the etched microstructures include semiconductor pillars disposed on the substrate, the semiconductor pillars extending in a direction perpendicular to a surface of the substrate.
3 . The method of claim 2 , wherein the semiconductor pillars contain or consist of silicon.
4 . The method of claim 2 , wherein the etched microstructures have an aspect ratio (height/width) greater than about 10.
5 . The method of claim 2 , wherein the etched microstructures have an aspect ratio (height/width) greater than about 50.
6 . The method of claim 1 , wherein the etch residue includes an etch polymer, an organic contamination, or both an etch polymer and an organic contamination.
7 . The method of claim 1 , wherein the wet chemical processing includes
exposing the substrate to an acidic aqueous solution;
rinsing the substrate with deionized (DI) water to remove the acidic aqueous solution from the substrate; and
exposing the substrate to a basic aqueous solution to clean and neutralize the substrate.
8 . The method of claim 7 , wherein the acidic aqueous solution contains a mixture of sulfuric acid (H 2 SO 4 ) and hydrogen peroxide (H 2 O 2 ).
9 . The method of claim 7 , wherein the basic aqueous solution contains a mixture of ammonium hydroxide (NH 4 OH) and hydrogen peroxide (H 2 O 2 ).
10 . The method of claim 1 wherein the rinsing and drying prevents stiction of the microstructures.
11 . A substrate processing method, comprising:
providing a substrate containing etched silicon pillars disposed on the substrate, where the etched silicon pillars extend in a direction perpendicular to a surface of the substrate, the etched silicon pillars containing etch residue thereon that includes an etch polymer, an organic contamination, or both an etch polymer and an organic contamination;
removing etch residue from the etched microstructure using wet chemical processing;
rinsing the substrate with an aqueous hydrogen fluoride solution after the wet chemical processing; and
drying the substrate using an inert gas to remove any water from the etched silicon pillars.
12 . The method of claim 11 , wherein the etched microstructures have an aspect ratio (height/width) greater than about 10.
13 . The method of claim 11 , wherein the wet chemical processing includes
exposing the substrate to an acidic aqueous solution;
rinsing the substrate with deionized (DI) water to remove the acidic aqueous solution from the substrate; and
exposing the substrate to a basic aqueous solution to clean and neutralize the substrate.
14 . The method of claim 13 , wherein the acidic aqueous solution contains a mixture of sulfuric acid (H 2 SO 4 ) and hydrogen peroxide (H 2 O 2 ).
15 . The method of claim 13 , wherein the basic aqueous solution contains a mixture of ammonium hydroxide (NH 4 OH) and hydrogen peroxide (H 2 O 2 ).
16 . The method of claim 11 , wherein the rinsing and drying prevents stiction of the microstructures.
17 . A substrate processing method, comprising:
providing a substrate containing etched silicon pillars disposed on the substrate, where the etched silicon pillars extend in a direction perpendicular to a surface of the substrate;
removing etch residue from the substrate using wet chemical processing, wherein the wet chemical processing includes
exposing the substrate to an acidic aqueous solution containing a mixture of sulfuric acid (H 2 SO 4 ) and hydrogen peroxide (H 2 O 2 ) to remove etch residue from the substrate;
rinsing the substrate with deionized (DI) water to remove the acidic aqueous solution from the substrate;
exposing the substrate to a basic aqueous solution containing a mixture of ammonium hydroxide (NH 4 OH) and hydrogen peroxide (H 2 O 2 ) to clean and neutralize the substrate;
rinsing the substrate with an aqueous hydrogen fluoride solution to render surfaces of the silicon pillars hydrophobic; and
drying the substrate using an inert gas to remove any water from the etched silicon pillars.
18 . The method of claim 17 , wherein the rinsing and drying prevents stiction of the etched silicon pillars.
19 . The method of claim 17 , wherein the etched silicon pillars have an aspect ratio (height/width) greater than about 10.
20 . The method of claim 17 , wherein the etch residue includes an etch polymer, an organic contamination, or both an etch polymer and an organic contamination.