Abstract A method for selectively masking a substrate surface, as in the fabrication of a semiconductor device, which includes the steps of forming a first layer of a masking material, e.g., silicon dioxide, on a surface of the substrate, forming an adherent layer of a second masking material, e.g., silicon nitride, on the first layer, and then forming a second layer of silicon dioxide on the silicon nitride layer. Openings are formed extending through preselected locations in the second oxide layer to expose underlying regions in the silicon nitride layer in a preselected pattern. The portions of silicon nitride exposed through the openings are selectively removed to expose preselected portions of the underlying first oxide layer, and then the exposed portions of the first oxide layer are removed to define a composite diffusion mask exposing preselected portions of the surface of the silicon semiconducor body. Subsequent diffusion and metallization steps may be then effected to form a semiconductor device.
A METHOD FOR PLURAL-STAGE THIN-FILM MASKING OF A SUBSTRATE COMPRISING: A. FORMING A FIRST ADHERENT, THIN-FILM MASK OF A MATERIAL RESISTANT TO A FIRST ETCHANT ON A SURFACE OF SAID SUBSTRATE, SAID MASK HAVING A PATTERN OF APERTURES THEREIN SELECTED TO PROVIDE ACCURATE SPACING BETWEEN A PLURALITY OF SUBTRATE LOCATIONS: B. FORMING A SECOND ADHERENT, THIN-FILM MASK OF A MATERIAL RESISTANT TO A SECOND ETCHANT, BUT NOT TO SAID FIRST ETCHANT ON SAID FIRST MASK SAID SECOND MASK HAVING A PATTERN OF APERTURES THEREIN WHICH EXPOSE ONLY A FIRST PRESELECTED NUMBER OF THE APERTURES IN SAID FIRST MASK; AND C. SUBSEQUENTLY FORMING A THIRD MASK, BE SELECTIVE ETCHING WITH SAID FIRST ETCHANT, ON SAID FIRST MASK, SAID THIRD MASK HAVING A PATTERN OF APERTURES THEREIN SELECTED TO EXPOSE ONLY A SECOND PRESELECTED NUMBER OF THE APERTURES IN SAID FIRST MASK.
Claim 2
Independent Claim
140 words
A METHOD FOR PLURAL-STAGE THIN-FILM MASKING OF A SUBSTRATE COMPRISING: A. FORMING A FIRST ADHERENT, THIN-FILM MASK OF A MATERIAL RESISTANT TO A FIRST ETCHANT ON A SURFACE OF SAID SUBSTRATE, SAID MASK HAVING A PATTERN OF APERTURES THEREIN SELECTED TO PROVIDE ACCURATE SPACING BETWEEN A PLURALITY OF SUBTRATE LOCATIONS: B. FORMING A SECOND ADHERENT, THIN-FILM MASK OF A MATERIAL RESISTANT TO A SECOND ETCHANT, BUT NOT TO SAID FIRST ETCHANT ON SAID FIRST MASK SAID SECOND MASK HAVING A PATTERN OF APERTURES THEREIN WHICH EXPOSE ONLY A FIRST PRESELECTED NUMBER OF THE APERTURES IN SAID FIRST MASK; AND C. SUBSEQUENTLY FORMING A THIRD MASK, BE SELECTIVE ETCHING WITH SAID FIRST ETCHANT, ON SAID FIRST MASK, SAID THIRD MASK HAVING A PATTERN OF APERTURES THEREIN SELECTED TO EXPOSE ONLY A SECOND PRESELECTED NUMBER OF THE APERTURES IN SAID FIRST MASK.
Claim 3
Dependent Claim
46 words
A method as defined by claim 1 wherein said substrate is an oxide-passivated semiconductor body, and wherein said method further includes the steps of etching apertures in the oxide after step (b), followed by selective diffusion of an impurity into the exposed locations of said semiconductor.
Claim 4
Dependent Claim
34 words
A method as defined by claim 2, further including the steps of etching apertures in the oxide after step (c), followed by selective diffusion of an impurity into the exposed locations of said semiconductor.
Claim 5
Dependent Claim
23 words
A method as defined by claim 3 wherein said first thin-film mask is silicon nitride, and said second thin-film mask is silicon dioxide.