Method of adjusting the threshold voltage of field effect transistors

Claim 1

A method of adjusting threshold voltages of field-effect transistors comprising the following steps: i. starting from a semiconductor wafer having a first type of conductivity, manufacturing a plurality of production devices destined to become field-effect transistors, each possessing a source, a drain, a gate constituted by a metal compound, and a semiconductor region destined to become the channel of a field-effect transistor, and concommitant manufacturing, in the same wafer, of a monitoring device possessing a source, a drain, a gate constituted by said metal compound and a semiconductor region respectively of the same type as the source, drain, gate and semiconductor region of any production transistor, and an appendix electrically connected to the gate of said monitoring device, and electrically insulated from the source and drain of said monitoring device, said appendix being made of the same metal compound as said gates having dimensions which make it possible to contact it with measuring means; ii. implanting ions in said wafer to modify the conductivity type of said regions, and concommitant measuring of the threshold voltage of said monitoring device, and iii. stopping ionic implantation when the threshold voltage, in the monitoring device reaches a predetermined value.

Claim 2

A method of adjusting threshold voltages of field-effect transistors comprising the following steps: i. starting from a semiconductor wafer having a first type of conductivity, manufacturing a plurality of production devices destined to become field-effect transistors, each possessing a source, a drain, a gate constituted by a metal compound, and a semiconductor region destined to become the channel of a field-effect transistor, and concommitant manufacturing, in the same wafer, of a monitoring device possessing a source, a drain, a gate constituted by said metal compound and a semiconductor region respectively of the same type as the source, drain, gate and semiconductor region of any production transistor, and an appendix electrically connected to the gate of said monitoring device, and electrically insulated from the source and drain of said monitoring device, said appendix being made of the same metal compound as said gates having dimensions which make it possible to contact it with measuring means; ii. implanting ions in said wafer to modify the conductivity type of said regions, and concommitant measuring of the threshold voltage of said monitoring device, and iii. stopping ionic implantation when the threshold voltage, in the monitoring device reaches a predetermined value.