Thermally-induced voltage alteration for integrated circuit analysis
First Claim
1. An apparatus for analyzing an integrated circuit (IC) formed on a semiconductor substrate, comprising:
- (a) a constant-current source connected to the IC to supply a constant current and a variable voltage thereto, the voltage provided by the constant-current source to the IC changing in response to a change in a power demand by the IC;
(b) a laser producing a beam with a photon energy less than a bandgap energy of the semiconductor substrate;
(c) means for focusing and scanning the laser beam to irradiate electrical conductors within the IC and thereby change the power demand by the IC when the laser beam irradiates any open-circuit or short-circuit defect in the IC, the focusing and scanning means providing a position signal to indicate the location of the laser beam on the IC; and
(d) display means comprising inputs of the changing voltage and the position signal for indicating the location of each open-circuit or short-circuit defect in the IC.
3 Assignments
0 Petitions
Accused Products
Abstract
A thermally-induced voltage alteration (TIVA) apparatus and method are disclosed for analyzing an integrated circuit (IC) either from a device side of the IC or through the IC substrate to locate any open-circuit or short-circuit defects therein. The TIVA apparatus uses constant-current biasing of the IC while scanning a focused laser beam over electrical conductors (i.e. a patterned metallization) in the IC to produce localized heating of the conductors. This localized heating produces a thermoelectric potential due to the Seebeck effect in any conductors with open-circuit defects and a resistance change in any conductors with short-circuit defects, both of which alter the power demand by the IC and thereby change the voltage of a source or power supply providing the constant-current biasing. By measuring the change in the supply voltage and the position of the focused and scanned laser beam over time, any open-circuit or short-circuit defects in the IC can be located and imaged. The TIVA apparatus can be formed in part from a scanning optical microscope, and has applications for qualification testing or failure analysis of ICs.
160 Citations
40 Claims
-
1. An apparatus for analyzing an integrated circuit (IC) formed on a semiconductor substrate, comprising:
-
(a) a constant-current source connected to the IC to supply a constant current and a variable voltage thereto, the voltage provided by the constant-current source to the IC changing in response to a change in a power demand by the IC; (b) a laser producing a beam with a photon energy less than a bandgap energy of the semiconductor substrate; (c) means for focusing and scanning the laser beam to irradiate electrical conductors within the IC and thereby change the power demand by the IC when the laser beam irradiates any open-circuit or short-circuit defect in the IC, the focusing and scanning means providing a position signal to indicate the location of the laser beam on the IC; and (d) display means comprising inputs of the changing voltage and the position signal for indicating the location of each open-circuit or short-circuit defect in the IC. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
-
-
22. An apparatus for analyzing an integrated circuit (IC) formed on a semiconductor substrate, comprising:
-
(a) a stage for holding the IC and making electrical connections thereto; (b) a laser generating a laser beam with a photon energy less than a bandgap energy of the semiconductor substrate; (c) means for focusing and scanning the laser beam onto the IC to irradiate electrical conductors within a portion of the IC and thereby produce by localized heating a thermoelectric potential at the location of any open-circuit defect in the electrical conductors; and (d) a constant-current source connected to the stage to supply power to the IC, the constant-current source further comprising a voltage that changes in response to the thermoelectric potential produced at the location of the open-circuit defect, the change in voltage thereby indicating the location of the open-circuit defect in the IC.
-
-
23. An apparatus for analyzing an integrated circuit (IC) formed on a semiconductor substrate, comprising:
-
(a) a stage for holding the IC and making electrical connections thereto; (b) a laser generating a laser beam with a photon energy less than a bandgap energy of the semiconductor substrate; (c) means for focusing and scanning the laser beam onto the IC to irradiate a short-circuit defect within the IC and thereby produce by localized heating a change in resistance of the short-circuit defect; and (d) a constant-current source connected to the stage to supply power to the IC, the constant-current source further comprising a voltage that changes in response to the change in resistance of the short-circuit defect, thereby indicating the location of the short-circuit defect in the IC.
-
-
24. A method for analyzing an integrated circuit (IC), comprising steps for:
-
(a) supplying electrical power to the IC from a constant-current source having a constant current and a variable voltage that changes in response to a change in a power demand by the IC; (b) irradiating electrical conductors within the IC by focusing and scanning a laser beam over a portion of the IC thereby changing the power demand by the IC, the laser beam having a photon energy less than a bandgap energy of a semiconductor substrate wherefrom the IC is formed; and (c) detecting at least one open-circuit or short-circuit defect within the IC by sensing a position of the focused and scanned laser beam and a change in the variable voltage from the constant-current source. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
-
Specification