Semiconductor integrated circuit device with protection against tampering

摘要

A semiconductor integrated circuit device has a circuit block formed on a semiconductor substrate, and an electrically conductive pattern formed in an upper layer of a portion of the circuit block that is to be protected. An oscillation circuit is connected to the electrically conductive pattern, and is configured to oscillate at an oscillation frequency determined by a circuit constant of the electrically conductive pattern, and a detection circuit is configured to determine whether a preset range includes the oscillation frequency of the oscillation circuit.

主权项

1. A semiconductor integrated circuit device comprising:
a semiconductor substrate; a circuit block formed on said semiconductor substrate; an electrically conductive pattern formed on at least a portion of said circuit block that is to be protected, with said portion to be protected being between said electrically conductive pattern and said semiconductor substrate; an oscillation circuit connected to said electrically conductive pattern, and configured to oscillate at an oscillation frequency determined by a circuit constant of said electrically conductive pattern; and a detection circuit configured to test the oscillation frequency of said oscillation circuit to determine whether the oscillation frequency of said oscillation circuit lies with a preset range, and to make a determination that said electrically conductive pattern has been altered if the oscillation frequency does not lie within the preset range, wherein said detection circuit comprises a counter circuit which counts the oscillation frequency of said oscillation circuit.