Laser-assisted device alteration using synchronized laser pulses
AssigneeFEI EFA, Inc.
InventorsPraveen Vedagarbha, Derryck Reid, Keith Serrels, James S. Vickers
Life of this patent
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Abstract
A pulsed-laser LADA system is provided, which utilizes temporal resolution to enhance spatial resolution. The system is capable of resolving CMOS pairs within the illumination spot using synchronization of laser pulses with the DUT clock. The system can be implemented using laser wavelength having photon energy above the silicon bandgap so as to perform single-photon LADA or wavelength having photon energy below the silicon bandgap so as to generate two-photon LADA. The timing of the laser pulses can be adjusted using two feedback loops tied to the clock signal of an ATE, or by adjusting the ATE's clock signal with reference to a fixed-pulse laser source.
Claims14
A method for altering a switching time of a device under test (DUT), the method comprising:
- determining marginal settings of the DUT;
- applying electrical test signals to the DUT using a tester to apply repetitive test signals based on the marginal settings to repeatedly stimulate the DUT at a pass/fail boundary;
- with a laser source, generating laser beam pulses having sufficient energy to generate electron-hole pairs within the DUT;
- scanning the laser beam pulses onto an area of interest in the DUT;
- controlling the timing of the laser source according to a clock of the tester;
- and
- wherein incident photon energy of the laser beam pulses is set to be less than a bandgap of material forming a device in the DUT.
A method for testing a device under test (DUT), the method comprising:
- applying a first set of electrical test signals from a tester to the DUT, so as to determine marginal settings for the DUT;
- setting voltage and frequency of a second set of electrical test signals of the tester according to the marginal settings for the DUT;
- generating electrical DUT output signals by repeatedly applying the second set of electrical test signals from the tester to the DUT;
- during the repeatedly applying, using a laser source to generate laser pulses of wavelength higher than silicon band gap;
- controlling timing of the laser pulses according to a clock signal from the tester;
- applying the laser pulses to an area of interest in the DUT to thereby generate electron-hole pairs within the DUT;
- and
- monitoring the electrical DUT output signals to determine location of a failure.
Dependencies are inferred from the claim text.