Method of making an ion implanted resistor

Claim 1

IN A METHOD FOR PRODUCING A RESISTOR IN A BODY OF CRYSTALLINE SILICON SEMICONDUCTOR MATERIAL OF N CONDUCTIVITY TYPE AND A KNOWN BULK RESISTIVITY AND HAVING A PLANAR SURFACE, FORMING A LAYER OF INSULATING MATERIAL HAVING A THICKNESS GREATER THAN APPROXIMATELY 1 MICRON ON SAID SURFACE, FORMING AT LEAST ONE OPENING IN SAID LAYER TO EXPOSE AN AREA OF SAID SURFACE, FORMING A PASSIVATING LAYER IN SAID OPENING HAVING A THICKNESS THROUGHOUT RANGING FROM APPROXIMATELY 1000 ANGSTROMS TO 3000 ANGSTROMS, IMPLANTING BORON IONS AT ROOM TEMPERATURE INTO SAID BODY THROUGH SAID PASSIVATING LAYER TO MODIFY THE CONDUCTIVITY OF THE PORTION OF THE BODY UNDERLYING SAID AREA OF SAID SURFACE TO PROVIDE AN IMPLANTED REGION HAVING AN IMPURITY CONCENTRATION RANGING FROM 10**14 TO 5 X 10**15 BORON IONS PER SQUARE CENTIMETER AND BEING DEFINED BY A PN JUNCTION EXTENDING TO SAID SURFACE, SAID LAYER OF INSULATING MATERIAL BEING SUFFICIENTLY THICK TO PREVENT SUBSTANTIALLY ANY OF SAID IONS FROM PENETRATING THERETHROUGH, SELECTIVELY VARYING EITHER THE ENERGY OF THE IONS OR THE THICKNESS OF THE PASSIVATING LAYER TO PROVIDE A SHEET RESISTIVITY RANGING FROM 870 TO 3000 OHMS PER SQUARE CENTIMETER WITH A TEMPERATURE VARIABILITY OF LESS THAN 3 PER CENT WITHIN THE TEMPERATURE RANGE OF-50*C TO 125*C, ANNEALING SAID BODY AT A TEMPERATURE OF 500*C TO 700*C, AND SECURING CONDUCTIVE LEADS TO SAID BODY TO MAKE CONTACT WITH SAID IMPLANTED REGION.