Method of fabricating thin film r-c circuits on single substrate

Claim 2

A PROCESS FOR FABRICATING A THIN RESISTANCECAPACITANCE CIRCUIT, COMPRISING THE FOLLOWING STEPS: (A) FORMING ON AN INSULATING SUBSTRATE A FIRST FILM OF A METAL HAVING A RELATIVELY HIGH SHEET RESISTIVITY, (B) FORMING ON SAID FIRST FILM A SECOND FILM OF A METAL HAVING A RELATIVELY LOW SHEET RESISTIVITY, (C) FORMING ON SAID SECOND FILM A THIRD FILM OF A METAL WHICH IS SURFACE OXIDIZABLE TO FORM AN INSULATING LAYER, (D) REMOVING A PORTION OF SAID THIRD FILM TO EXPOSE A PORTION OF SAID SECOND FILM AND LEAVE A PART PORTION OF SAID THIRD FILM WHEREBY AT LEAST A PART OF SAID REAMINING PORTION IS OXIDIZABLE TO SERVE AS A CAPACITOR DIELECTRIC, (E) REMOVING PART OF SAID EXPOSED PORTION OF SAID SECOND FILM TO EXPOSE A PORTION OF SAID FIRST FILM AND LEAVE A REMAINING PORTION OF SAID SECOND FILM, SAID REMAINING PORTION OF SAID SECOND FILM BEING ARRANGED TO SERVE AS AT LEAST ONE CAPACITOR ELETRODE, (F) REMOVING PART OF SAID EXPOSED PORTION OF SAID FIRST FILM TO FORM AT LEAST ONE RESISTOR OF THE REMAINING PORTION OF SAID FIRST FILM, (G) OXIDIZING SAID PART OF SAID REMAINING PORTION OF SAID THIRD FILM, THEREBY TO FORM A DIELECTRIC AREA, AND (H) PLACING A METALLIC CAPACITOR COUNTER ELECTRODE HAVING A RELATIVELY LOW SHEET RESISTIVITY OVER AT LEAST A PORTION OF THE OXIDIZED PART OF SAID THIRD FILM.

Claim 3

A PROCESS FOR PREPARING MICROMINIATURE, THIN FILM, RESISTANCE CAPACITANCE CIRCUITS, COMPRISING THE FOLLOWING STEPS: (A) SPUTTERING A TANTALUM FIRST FILM ONTO A GLASS SUBSTRATE, (B) SPUTTERING A GOLD SECOND FILM ONTO SAID FIRST FILM, (C) SPUTTERING A TANTALUM THIRD FILM ONTO SAID SECOND FILM, (D) PHOTOLITHORGRAPHICALLY ETCHING AWAY A PORTION OF SAID THIRD FILM TO LEAVE REMAINING AT LEAST ONE AREA THEREOF FOR FORMATION OF A CAPACITOR DIELECTRIC, AND ALSO TO EXPOSE A PORTION OF SAID SECOND FILM, (E) PHOTOLITHOGRAPHICALLY ETCHING AWAY A PORTION OF SAID SECOND FILM TO LEAVE REMAINING AN AREA THEREOF AT LEAST PARTIALLY UNDERNEATH SAID REAINING AREA OF SAID THIRD FILM, THEREBY TO FORM A BOTTOM CAPACITOR ELECTRODE, AND AT LEAST ONE OTHER AREA THEREOF TO FORM A RESISTOR CONTACT, (F) PHOTOLITHOGRAPHICALLY ETCHING AWAY AT LEAST A PORTION OF THE EXPOSED AREA OF SAID FIRST FILM OT EXPOSE A PORTION OF SAID SUBSTRATE AND LEAVE AT LEAST ONE REMAINING RESISTIVE STRIP OF SAID FIRST FILM, SAID RESISTIVE STRIP HAVING WIDENED CONTACT AREAS AT SPACED LOCATIONS THEREON, SAID CONTACT AREAS LYING UNDER PORTIONS OF SAID SECOND FILM, (G) ANODICALLY OXIDIZING SAID AREA OF SAID THIRD FILM, THEREBY TO FORM AN INSULATING LAYER TO SERVE AS A CAPACIOR DIELECTRIC, AND (H) EVAPORATING A CONDUCTIVE FILM OVER THE OXIDIZED AREA OF SAID THIRD FILM TO FORM AN UPPER ELECTRODE OF SAID CAPACITOR.

Claim 4

A PROCESS FOR PREPARING MICROMINIATURE, THIN FILM, RESISTANCE CAPACITANCE CIRCUITS, COMPRISING THE FOLLOWING STEPS: (A) SPUTTERING A TANTALUM FIRST FILM ONTO A GLASS SUBSTRATE, (B) SPUTTERING A GOLD SECOND FILM ONTO SAID FIRST FILM, (C) SPUTTERING A TANTALUM THIRD FILM ONTO SAID SECOND FILM, (D) PHOTOLITHORGRAPHICALLY ETCHING AWAY A PORTION OF SAID THIRD FILM TO LEAVE REMAINING AT LEAST ONE AREA THEREOF FOR FORMATION OF A CAPACITOR DIELECTRIC, AND ALSO TO EXPOSE A PORTION OF SAID SECOND FILM, (E) PHOTOLITHOGRAPHICALLY ETCHING AWAY A PORTION OF SAID SECOND FILM TO LEAVE REMAINING AN AREA THEREOF AT LEAST PARTIALLY UNDERNEATH SAID REAINING AREA OF SAID THIRD FILM, THEREBY TO FORM A BOTTOM CAPACITOR ELECTRODE, AND AT LEAST ONE OTHER AREA THEREOF TO FORM A RESISTOR CONTACT, (F) PHOTOLITHOGRAPHICALLY ETCHING AWAY AT LEAST A PORTION OF THE EXPOSED AREA OF SAID FIRST FILM OT EXPOSE A PORTION OF SAID SUBSTRATE AND LEAVE AT LEAST ONE REMAINING RESISTIVE STRIP OF SAID FIRST FILM, SAID RESISTIVE STRIP HAVING WIDENED CONTACT AREAS AT SPACED LOCATIONS THEREON, SAID CONTACT AREAS LYING UNDER PORTIONS OF SAID SECOND FILM, (G) ANODICALLY OXIDIZING SAID AREA OF SAID THIRD FILM, THEREBY TO FORM AN INSULATING LAYER TO SERVE AS A CAPACIOR DIELECTRIC, AND (H) EVAPORATING A CONDUCTIVE FILM OVER THE OXIDIZED AREA OF SAID THIRD FILM TO FORM AN UPPER ELECTRODE OF SAID CAPACITOR.