Electrochemical method and apparatus therefor

Claim 1

IN A METHOD FOR PRODUCING A REGION OF PARTICULAR THICKNESS IN AN N-TYPE SEMICONDUCTIVE BODY HAVING A RECTIFYING BARRIER THEREIN, THE STEPS OF: APPLYING TO AN EXPOSED SURFACE OF SAID BODY OPPOSING SAID BARRIER AN ELECTRICALLY-CONDUCTIVE SOLUTION CONTAINING IONS OF A METAL FORMING A SURFACE-BARRIER WHEN APPLIED TO SAID BODY; SUPPLYING TO SAID SOLUTION DURING A FIRST GROUP OF TIME-SPACED INTERVALS A FIRST INPUT CURRENT HAVING A SENSE SUCH AS TO ESTABLISH SAID SOLUTION AT A POTENTIAL NEGATIVE WITH RESPECT TO THAT OF SAID BODY, THEREBY TO PRODUCE ELECTROLYTIC ETCHING OF SAID BODY; SUPPLYING TO SAID SOLUTION DURING A SECOND GROUP OF TIME-SPACED INTERVALS INTERMEDIATE SAID FIRST GROUP A SECND INPUT CURRENT HAVING A PARTICULAR INTENSITY AND A SENSE OPPOSITE SAID FIRST-NAMED SENSE, THEREBY TO CAUSE SAID METAL TO BE ELECTRODEPOSITED ON SAID OPPOSING SURFACE AND SAID ELECTRODEPOSITED METAL TO INJECT HOLES INTO SAID SEMICONDUCTIVE BODY, APPLYING TO SAID RECTIFYING BARRIER AT LEAT DURING SAID INTERVALS OF SAID SECOND GROUP A POTENTIAL NEGATIVE WITH RESPECT TO THAT OF SAID BODY AND HAVING A MAGNITUDE LESS THAN THAT PRODUCING AN ABRUPT IN THE IMPEDANCE BETWEEN SAID TWO RECTIFYING CONTACTS WHEN SAID REGION HAS SAID PARTICULAR THICKNESS, THEREBY TO COLLECT THOSE OF SAID INJECTED HOLES DIFFUSING INTO THE VICINITY OF SAID FIRST RECTIFYING BARRIER, AND DETECTING THE PORTION OF SAID INJECTED HOLES OF THE CURRENT FLOWING THERETHROUGH, THEREBY TO OBTAIN AN INDICATION OF THE THICKNESS OF SAID BODY REGION.