Method for reducing leaching in metal-coated MEMS
View Patent ↗A method is provided for preventing dopant leaching from a doped structural film during fabrication of a microelectromechanical system. A microstructure that includes the doped structural film, sacrificial material, and metallic material is produced with a combination of deposition, patterning, and etching techniques. The sacrificial material is dissolved with a release solution that has a substance destructive to the sacrificial material. This substance also acts as an electrolyte, forming a galvanic cell with the doped structural film and metallic material acting as electrodes. The effects of the galvanic cell are suppressed by including a nonionic detergent mixed in the release solution.
1. A method for fabricating a microelectromechanical system, the method comprising:
producing an intermediate microstructure that includes a doped structural film, sacrificial material, and metallic material;
dissolving the sacrificial material from the intermediate microstructure with an acid to form the microelectromechanical system; and
suppressing dopant leaching from the doped structural film while dissolving the sacrificial material by including a nonionic detergent in the acid.
2. The method recited in claim 1 wherein the doped structural film comprises a doped semiconductor.
3. The method recited in claim 1 wherein the doped structural film comprises doped silicon.
4. The method recited in claim 3 wherein the doped structural film comprises doped polysilicon.
5. The method recited in claim 1 wherein the metallic material comprises a material selected from the group consisting of gold, aluminum, copper, platinum, and nickel.
6. The method recited in claim 1 wherein the nonionic detergent comprises an alkyl group and a polyether-linked hydroxy group commonly linked to an aryl group.
7. The method recited in claim 1 wherein the nonionic detergent is included with a concentration relative to the acid approximately between 0.01 and 0.1 vol. %.
8. The method recited in claim 1 wherein the nonionic detergent comprises a hydrophilic moiety and a hydrophobic moiety commonly linked to an aryl group.
9. A microelectromechanical system fabricated according to the method recited in claim 1 .
10. A method for fabricating a microelectromechanical system, the method comprising:
producing an intermediate microstructure that includes a doped silicon film, sacrificial material, and a metallic material selected from the group consisting of gold, aluminum, copper, platinum, and nickel;
dissolving the sacrificial material from the intermediate microstructure with an acid to form the microelectromechanical system; and
suppressing dopant leaching from the doped silicon film while dissolving the sacrificial material by including a substance comprising an alkyl group and a polyether-linked hydroxy group commonly linked to an aryl group in the acid.
11. The method recited in claim 10 wherein the doped silicon film comprises a doped polysilicon film.
12. The method recited in claim 10 wherein the substance is included with a concentration relative to the acid approximately between 0.01 and 0.1 vol. %.
13. A microelectromechanical system made according to the method recited in claim 10 .
14. A method for fabricating a microelectromechanical system, the method comprising:
producing an intermediate microstructure that includes a doped silicon film, sacrificial material, and a metallic material selected from the group consisting of gold, aluminum, copper, platinum, and nickel;
dissolving the sacrificial material from the intermediate microstructure with an acid to form the microelectromechanical system; and
suppressing dopant leaching from the doped structural film while dissolving the sacrificial material by including a substance comprising a hydrophilic moiety and a hydrophobic moiety commonly linked to an aryl group in the solution.
15. The method recited in claim 14 wherein the doped silicon film comprises a doped polysilicon film.
16. The method recited in claim 14 wherein the substance is included with a concentration relative to the acid approximately between 0.01 and 0.1 vol. %.