Breakdown voltage resistor obtained through a double ion-implantation into a semiconductor substrate, and manufacturing process of the same

Claim 1

A process of forming an implanted resistor in a semiconductor substrate of a first type of conductivity, comprising the following steps: implanting a impurity of a second type of conductivity opposite to said first type of conductivity into a region of the substrate, at a first heavy dose within about 10 12 -10 15 at/cm 2 , at a low energy within about 20-120 KeV in order to define the required value of the resistor and bring about a low TCR, implanting an impurity of said second type of conductivity into said region, at a second dose within about 10 11 -10 14 at/cm 2 , which is lighter than said heavy dose, and at a higher energy within about 120-400 KeV, in order to ensure an improved breakdown voltage without substantially modifying the required value of the resistor, and annealing the substrate, the ratio of atoms implanted in said heavy dose to the atoms implanted in said lighter dose being at least about 10.