Method for detecting thinning of the substrate of an integrated circuit from its back side, and associated integrated circuit

An integrated electronic circuit, comprising:

• a semiconductor substrate, including a semiconductor well of a first conductivity type that is isolated by a buried semiconductor layer of a second conductivity type opposite the first conductivity type, said buried semiconductor layer located under the semiconductor well;
• and
• a device configured to detect back side thinning of the semiconductor substrate, comprising:
• a vertical MOS transistor including a first semiconductor electrode region located on a front side of the semiconductor substrate, and an insulated vertical gate region extending between the first semiconductor electrode region and the buried semiconductor layer which includes a second semiconductor electrode region of the vertical MOS transistor;
• a biasing circuit configured to bias the vertical MOS transistor in an on state;
• and
• a comparing circuit coupled to one of the first and second semiconductor electrode regions and configured to compare a current delivered by said one of the first and second semiconductor electrode regions in the on state with a threshold value and to generate a control signal having a first value corresponding to detection of non-thinning of the semiconductor substrate if the value of said current is higher than the threshold value, and having a second value corresponding to detection of thinning of the semiconductor substrate if the value of the current is lower than the threshold value.

A method for detecting back side thinning of a semiconductor substrate of an integrated circuit, wherein the semiconductor substrate includes:

• a semiconductor well isolated by a buried semiconductor layer located under the semiconductor well;
• and
• a vertical MOS transistor including a first semiconductor electrode region located on a front side of the semiconductor substrate, and an insulated vertical gate region extending between the first semiconductor electrode region and the buried semiconductor layer which includes a second semiconductor electrode region of the vertical MOS transistor;
• the method comprising:
• biasing the vertical MOS transistor to a transistor on state;
• comparing a current flowing between the first and second semiconductor electrode regions of the vertical MOS transistor with a threshold value when the vertical MOS transistor is biased in the on state;
• and
• generating a control signal having a first value corresponding to detection of non-thinning of the semiconductor substrate if the value of said current is higher than the threshold value, and having a second value corresponding to detection of thinning of the semiconductor substrate if the value of the current is lower than the threshold value.