Abstract A method for producing tucked-under, passivated PN junctions in semiconductor devices by ion implantation through a layered mask. The mask comprises a first relatively thin dielectric layer and a conductive layer thereover. An aperture is formed in the conductive layer, and the structure is subjected to a beam of dopant ions having energy sufficient to penetrate the dielectric layer but insufficient to penetrate the combined layers. In this fashion a PN junction is formed in the semiconductor body underneath the aperture in the conductive layer. Then the conductive layer is caused to become thicker, e.g., by electroplating, which also causes the aperture in the second layer to become smaller in lateral dimension. Then, using the conductive layer as a mask, the portion of the dielectric layer exposed through the aperture is selectively removed, e.g., by backsputtering. In this manner there is exposed a portion of the surface which is smaller than the implanted zone.
A method as recited in claim 1 wherein: the first coating is nonconductive and the second coating is conductive.
Claim 2
Dependent Claim
18 words
A method as recited in claim 2 wherein: the conductive coating is caused to become thicker by electroplating.
Claim 3
Dependent Claim
45 words
A method as recited in claim 1 wherein: the first coating comprises a material selected from the group consisting of silicon oxide, silicon nitride and aluminum oxide; and the second coating comprises a material selected from the group consisting of gold, platinum, nickel and zirconium.
Claim 4
Independent Claim
148 words
A method of forming by ion implantation a localized zone in a semiconductive body comprising the steps of: forming a substantially uniform nonconductive coating on a surface of the body; forming a substantially uniform conductive coating over and contiguous with the nonconductive coating; forming an aperture in the conductive coating over that portion of the body in which the localized zone is to be formed; subjecting the structure to a beam of dopant ions having energy sufficient to penetrate the nonconductive coating and sufficient to alter the semiconductivity of the body under the aperture in the conductive coating but insufficient to penetrate completely the combined conductive coating and nonconductive coatings; electroplating the conductive coating so that the conductive coating becomes thicker and the aperture in the conductive coating becomes smaller; and removing the portion of the nonconductive layer exposed by the remaining smaller aperture in the conductive layer.
Claim 5
Dependent Claim
41 words
A method as recited in claim 5 wherein: the nonconductive coating is selected from the group consisting of silicon oxide, silicon nitride and aluminum oxide; and the conductive coating is selected from the group consisting of gold, platinum, nickel and zirconium.
Claim 6
Dependent Claim
29 words
A method as recited in claim 5 wherein backsputtering is used to remove the portion of the nonconductive layer exposed by the remaining smaller aperture in the conductive layer.