Process for anisotropic etching of silicon plates

Details Process for anisotropic etching of silicon plates Process for anisotropic etching of silicon plates

1990-09-24

1991-12-10

Powell, William A.

Adhesive bonding and miscellaneous chemical manufacture

Delaminating processes adapted for specified product

Delaminating in preparation for post processing recycling step

156627, 156628, 156651, 156653, 156657, 1566611, 156662, 20412965, 437238, 437241, 437245, H01L 21306, B44C 122, C03C 1500, C03C 2506

Patent

active

050715100

ABSTRACT:
Electrochemical etching of silicon wafers or plates, on the front side of which a monocrystalline epitaxy layer is provided having a doping of a type opposite to the doping of the remainder of the silicon plate, so as to provide a pn or np junction, is performed with an organic photo film material of negative type and polyisoprene base serving as a passivating layer on the previously etched and metallized front (epitaxy) side. The film layer is held in place with the help of an adhesion promoting silane compound and covers the entire front side including the portions previously masked with silicon nitride or oxide. It is dried and hardened before exposure to the etchant which is used to etch the rear side of the plate until the etchant reaches the pn junction, where a small voltage bias applied to the junction from the front side assures an etch-stop. Etchants containing tetraalkylammonium hydroxide in water solution or in water-free form are preferred, with various additives as inhibitors, complexing agents and/or wetting agents.

REFERENCES:
patent: 4089704 (1978-05-01), Heiss et al.
patent: 4113551 (1978-09-01), Bassous et al.
patent: 4172005 (1979-10-01), Muraoka et al.
patent: 4765865 (1988-08-01), Gealer et al.
RCA Review--"Chemical Etching of Silicon, Germanium, Gallium Arsenide, and Gallium Phosphide", by Werner Kern, vol. 39, Jun. 1978, pp. 278-308.

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