Method of protecting an integrated circuit chip against spying by laser attacks

摘要

The method involves forming an impurities trapping zone (23) extended below an active part (5), in a semiconductor substrate (3) by introducing inert gas i.e. helium, in the semiconductor substrate, where an upper limit of the trapping zone is at a depth ranging from 5 to 50 micrometer, from an upper face of the semiconductor substrate. Diffusing metal impurities with concentration ranging between 10power17 and 10power18 atoms per cubic centimeter, are introduced in the semiconductor substrate, where the impurities are retained in the trapping zone. The trapping zone is formed by precipitation of oxygen. The metal impurities contain iron atoms. An independent claim is also included for an integrated circuit chip comprising an active part.