Planar structure semiconductor device and method of making the same

Claim 1

A METHOD OF MAKING A SEMICONDUCTOR DEVICE OF PLANAR STRUCTURE COMPRISING THE STEPS OF: A. DEPOSITING A FILM OF AT LEAST ONE REFRACTORY METAL SELECTED FROM THE GROUP CONSISTING OF TANTALUM, NIOBIUM, TITANIUM, ZIRCONIUM AND HAFNIUM ON ONE MAIN SURFACE OF AN N-TYPE 111-V GROUP COMPOUND SEMICONDUCTOR WAFER TO A THICKNESS IN THE RANGE OF 500 TO 3,000 A BY SPUTTERING B. ADHERING A RESIST FILM ON A PREDETERMINED PORTION OF SAID REFRACTORY METAL FILM, E. IMMERSING THE N-TYPE SEMICONDUCTOR WAFER IN A REACTION LIQUID CONSISTING OF OXALIC ACID, ETHYLENE GYCOL AND WATER TO CONVERT SAID REFRACTORY METAL FILM INTO AN OXIDE FILM OF SAID REFRACTRY METAL BY MEAS OF ANODIZATION WHILE LEAVING THE PORTION DIRECTLY BENEATH THE RESIST FILM NOT CONVERTED, D. REMOVING SAID RESIST FILM THROUGH CHEMICAL ETCHING AND E. HEATING THE N-TYPE SEMICONDUCOR WAFER IN SEALED TUBE IN THE PRESENCE OF A N-TYPE PREDETERMINED IMPURITY SELECTED FROM THE GROUP CONSISTING OF ZINC AND CADMIUM TO DIFFUSE SAID IMPURITY THROUGH SAID REFRACTORY METAL FILM TO FORM A P-TYPE REGION OF HIGH CONCENTRATION OF SAID IMPURITY DIRECTLY BENEATH SAID REFRACTORY METAL FILM.

Claim 2

A METHOD OF MAKING A SEMICONDUCTOR DEVICE OF PLANAR STRUCTURE COMPRISING THE STEPS OF: A. DEPOSITING A FILM OF AT LEAST ONE REFRACTORY METAL SELECTED FROM THE GROUP CONSISTING OF TANTALUM, NIOBIUM, TITANIUM, ZIRCONIUM AND HAFNIUM ON ONE MAIN SURFACE OF AN N-TYPE 111-V GROUP COMPOUND SEMICONDUCTOR WAFER TO A THICKNESS IN THE RANGE OF 500 TO 3,000 A BY SPUTTERING B. ADHERING A RESIST FILM ON A PREDETERMINED PORTION OF SAID REFRACTORY METAL FILM, E. IMMERSING THE N-TYPE SEMICONDUCTOR WAFER IN A REACTION LIQUID CONSISTING OF OXALIC ACID, ETHYLENE GYCOL AND WATER TO CONVERT SAID REFRACTORY METAL FILM INTO AN OXIDE FILM OF SAID REFRACTRY METAL BY MEAS OF ANODIZATION WHILE LEAVING THE PORTION DIRECTLY BENEATH THE RESIST FILM NOT CONVERTED, D. REMOVING SAID RESIST FILM THROUGH CHEMICAL ETCHING AND E. HEATING THE N-TYPE SEMICONDUCOR WAFER IN SEALED TUBE IN THE PRESENCE OF A N-TYPE PREDETERMINED IMPURITY SELECTED FROM THE GROUP CONSISTING OF ZINC AND CADMIUM TO DIFFUSE SAID IMPURITY THROUGH SAID REFRACTORY METAL FILM TO FORM A P-TYPE REGION OF HIGH CONCENTRATION OF SAID IMPURITY DIRECTLY BENEATH SAID REFRACTORY METAL FILM.

Claim 3

A method of making a semiconductor device of planar structure comprising the steps of: a. depositing a tantalum film 3,000 A thick on one main surface of an n-type GaAs crystal wafer doped with about 3 X 1017 cm 3 of tellurium by d.c. sputtering: b. adhering a resist film covering an area corresponding to a diffusion window on the tantalum film; c. immersing the GaAs crystal wafer in a mixture solution consisting of one part of oxalic acid, three part of ethylene glycol and two part of water and applying anodization to the n-type GaAs crystal wafer using the GaAs crystal wafer as an anode and a carbon plate disposed in a reaction tube as a cathode in order to transform the tantalum film other than the portion directly under said resist film into Ta2O5, the reaction voltage employed in the anodization being gradually raised at a rate of about 1 V/min.; d. removing said resist film through chemical etching; e. vacuum-sealing the GaAs crystal wafer in a quartz ampoule with ZnAs2 serving as an impurity source, and thereafter heating it at about 700*C for 5 hours so as to diffuse zinc in the one main surface of the n-type GaAs crystal wafer just under said tantalum film and in the other exposed main surface thereof to form p-type regions of high impurity concentration each about 5 Mu thick; f. chemical etching the p-type zinc diffused region formed in the other main surface of the GaAs crystal wafer; g. vacuum-depositing a gold-chromium film containing 3 to 15 % of chromium, and gold-germanium alloy film containing about 5 % of germanium, on both the tantalum film and the Ta2O5 film and on the other main surface of the GaAs crystal wafer, respectively.

Claim 4

A method of making a semiconductor device of planar structure comprising the steps of: a. depositing a tantalum film 3,000 A thick on one main surface of an n-type GaAs crystal wafer doped with about 3 X 1017 cm 3 of tellurium by d.c. sputtering: b. adhering a resist film covering an area corresponding to a diffusion window on the tantalum film; c. immersing the GaAs crystal wafer in a mixture solution consisting of one part of oxalic acid, three part of ethylene glycol and two part of water and applying anodization to the n-type GaAs crystal wafer using the GaAs crystal wafer as an anode and a carbon plate disposed in a reaction tube as a cathode in order to transform the tantalum film other than the portion directly under said resist film into Ta2O5, the reaction voltage employed in the anodization being gradually raised at a rate of about 1 V/min.; d. removing said resist film through chemical etching; e. vacuum-sealing the GaAs crystal wafer in a quartz ampoule with ZnAs2 serving as an impurity source, and thereafter heating it at about 700*C for 5 hours so as to diffuse zinc in the one main surface of the n-type GaAs crystal wafer just under said tantalum film and in the other exposed main surface thereof to form p-type regions of high impurity concentration each about 5 Mu thick; f. chemical etching the p-type zinc diffused region formed in the other main surface of the GaAs crystal wafer; g. vacuum-depositing a gold-chromium film containing 3 to 15 % of chromium, and gold-germanium alloy film containing about 5 % of germanium, on both the tantalum film and the Ta2O5 film and on the other main surface of the GaAs crystal wafer, respectively.

Claim 5

A method of making a semiconductor device of planar structure comprising the steps of: a. depositing a film of at least one refractory metal selected from the group consisting of tantalum, niobium, titanium, zirconium and hafnium one one main surface of an n-type III - V group compound semiconductor wafer to a thickness in the range of 500 to 3,000 A by sputtering: b. adhering a resist film on a predetermined portion of said refractory metal film; c. immersing the n-type semiconductor wafer in a reaction liquid to convert said refractory metal film into an oxide film of said refractory metal by means of anodization while leaving the portion directly beneath the resist film not converted; d. removing said resist film through chemical etching; and e. heating the n-type semiconductor wafer in the presence of a p-type predetermined impurity to diffuse said impurity through said refractory metal film to form a p-type region of high concentration of said impurity directly beneath said refractory metal film.

Claim 6

A method of making a semiconductor device of planar structure comprising the steps of: a. depositing a film of at least one refractory metal selected from the group consisting of tantalum, niobium, titanium, zirconium and hafnium one one main surface of an n-type III - V group compound semiconductor wafer to a thickness in the range of 500 to 3,000 A by sputtering: b. adhering a resist film on a predetermined portion of said refractory metal film; c. immersing the n-type semiconductor wafer in a reaction liquid to convert said refractory metal film into an oxide film of said refractory metal by means of anodization while leaving the portion directly beneath the resist film not converted; d. removing said resist film through chemical etching; and e. heating the n-type semiconductor wafer in the presence of a p-type predetermined impurity to diffuse said impurity through said refractory metal film to form a p-type region of high concentration of said impurity directly beneath said refractory metal film.