Method of creating sharp points and other features on the surfac

Details Method of creating sharp points and other features on the surfac Method of creating sharp points and other features on the surfac

1992-02-14

1994-10-25

Fourson, George

Fishing, trapping, and vermin destroying

437153, 437157, 437986, 156628, 156643, 156648, H01L 21465

Patent

active

053589084

ABSTRACT:
A method of producing sharp points on the surface of a substrate is described. The points are useful as field emitter tips, and may also be used to collect radiant energy and for the production of micromachined objects such as micron sized gears and levers. Conventional techniques of asperity fabrication typically use an undercut of a hard mask to etch away the substrate material. This conventional method is very time specific and difficult to control. The inventive process uses a more easily controlled etch than conventional asperity fabrication techniques. The inventive process begins with a substrate highly doped with a P-type dopant such as boron which prevents an etch with KOH or other material. A hard mask is patterned over the substrate surface, and an N-type dopant, such as phosphorous or arsenic, is implanted into the substrate surface. The N-type dopant diffuses under the hard mask at a rate more easily controlled than the etch used in conventional techniques. The N-type dopant counterdopes the boron implanted substrate, thereby making the substrate etchable. The mask is removed and the substrate is etched, thereby removing the counterdoped areas and leaving the P-doped areas, which includes the asperity.

REFERENCES:
patent: 4372033 (1983-02-01), Chiao
patent: 4419811 (1983-12-01), Rice
patent: 4857478 (1989-08-01), Niwano et al.
patent: 5104517 (1992-04-01), Scott
Wolf, S. and R. Tauber, "Silicon Processing for the VLSI ERA" Lattice Press, Sunset Beach, Calif., vol. 1, 1986, pp. 531-532.

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