Apparatus and method for analyzing functional failures in integrated circuits

An apparatus for analyzing an integrated circuit (IC) to locate any signal propagation paths that produce timing errors within the IC that result in an incorrect value of an output voltage from the IC, comprising:

• (a) means for operating the IC under conditions which produce an incidence of the timing errors in the IC in response to a set of input test vectors provided to the IC;
• (b) a laser having a laser beam with a photon energy less than a bandgap energy of a semiconductor substrate whereon the IC is formed;
• (c) a scanning optical microscope for receiving the laser beam and producing therefrom a focused laser beam which is scanned across a portion of the IC, with the scanning optical microscope further generating a position signal indicative of the position of the focused laser beam at any instant in time, and with the focused laser beam producing localized heating within the IC that changes the incidence of the timing errors in the IC;
• (d) means connected to the IC for measuring the output voltage from the IC and generating therefrom an analytical output signal whenever the output voltage switches between the incorrect value and a correct value;
• and
• (e) a display for receiving the position signal and the analytical output signal and generating therefrom a map for locating each signal propagation path within the IC responsible for producing the timing errors.

A method for analyzing an integrated circuit (IC) and identifying any circuit elements in the IC responsible for producing functional failures in the IC, comprising steps for:

• (a) controlling operational parameters of the IC to induce a level of incidence of the functional failures therein, with the functional failures producing an incorrect value of an output voltage from the IC in response to a set of input test vectors provided to the IC;
• (b) scanning the IC with a focused laser beam having a photon energy less than a bandgap energy of a substrate whereon the IC is formed to locally heat circuit elements within the IC, thereby changing the level of incidence of the functional failures in the IC;
• and
• (c) measuring the change in the level of incidence of the functional failures in the IC as a function of the position of the focused laser beam incident on the IC, thereby locating the circuit elements in the IC responsible for producing the functional failures in the IC.