Radiation Induced Fault Analysis for Semiconductor Defect Localization
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Solution Overview
Problem
Current radiation-based stimulation techniques, such as LADA and SDL, are ineffective in determining the location of 'hard' defects in semiconductor devices, as they rely on voltage, frequency, and temperature variations, which are independent of physical defects, and software techniques are limited by simplified models and computational resources, failing to accurately identify defect locations, especially for functional tests.
Innovation Solution
The Radiation Induced Fault Analysis (RIFA) test system uses a laser beam to induce temporary faults in a correlation device, comparing test signatures to identify defect locations by mimicking the behavior of a failed device, allowing for both hard and soft defect localization without damaging the semiconductor die.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If LADA and SDL techniques are used to analyze voltage, frequency and temperature sensitive devices, then soft defects can be identified, but hard defect locations cannot be determined
Solution Approach 1:
The invention changes the testing parameter from electrical characteristics (voltage, frequency, temperature) to optical characteristics (laser wavelength, power, pulse width). By using optical parameters to induce and detect defects, the system can identify both soft defects (through electrical characteristic changes) and hard defects (through optical property changes), thereby resolving the contradiction between detecting soft defects and adapting to hard defect analysis.
Solution Approach 2:
The invention introduces optical radiation (laser) as an intermediary to interact with the semiconductor device. This optical intermediary can induce faults and modify circuit operation in a way that reveals defect locations, serving as a bridge between the testing system and the device under test, enabling detection of both soft and hard defects that electrical testing alone cannot detect.
2Measurement precision
If software techniques with design models and simulations are used, then potential defect locations can be predicted, but accuracy is limited by simplified models and computational resources
Solution Approach 1:
The invention replaces software-based computational models with a physical optical testing system. Instead of using complex simulations and algorithms to predict defect locations, the system uses optical radiation to directly interact with the device and induce faults, providing physical evidence of defect locations without relying on simplified computational models.
Solution Approach 2:
The invention creates a correlation device that copies the circuit structure of the failed device, allowing the same optical testing procedure to be applied to both devices. This copying approach enables direct comparison and identification of defect locations without requiring complex software models to simulate the failed device's behavior.
3Measurement precision
If laser power is increased to induce faults in correlation device, then defect location can be identified, but semiconductor die may be damaged
Solution Approach 1:
The invention applies partial action by using low enough laser power to induce faults in the correlation device without causing permanent damage, while still providing sufficient power to identify defect locations. The laser power is carefully controlled to be excessive enough to trigger fault induction but insufficient to cause harmful effects on the semiconductor die, resolving the contradiction between detection capability and device protection.
Solution Approach 2:
The invention uses a correlation device as a sacrificial placeholder that can withstand the optical testing process. By testing the correlation device instead of the actual failed device, the system cushions the valuable semiconductor die from potential damage while still enabling defect location identification through the correlation device's response to optical radiation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
RIFA effectively isolates and determines the location of defects in semiconductor devices, improving fault analysis accuracy and efficiency by inducing controlled faults in the correlation device, which matches the failure signature of the failed device, enabling timely identification of defects in mass-produced integrated circuits.
Implementation Method 1
A laser operating at a wavelength of approximately 1,064 nanometers (nm) produces localized photocurrents within active transistor layers in which the photo-generated currents modify circuit timing or voltage levels
Implementation Method 2
A laser operating at a wavelength of approximately 1,340 nm produces localized heating which also alters circuit timing (e.g., slowing down of logic transitions)
Data Source
AI summary
A method of locating a defect of a failed semiconductor device which includes applying a test pattern to the failed semiconductor device and providing failed semiconductor device test responses as a pass signature, applying radiation to each of multiple locations of circuitry of a correlation semiconductor device with sufficient energy to induce a fault in the circuitry, applying the test pattern to the correlation semiconductor device while the radiation is applied to the location and comparing correlation semiconductor device test responses with the pass signature for each location, and determining a defect location of the failed semiconductor device in which correlation semiconductor device test responses at least nearly match the pass signature. The radiation may be a laser beam. The method may include determining an exact match or a near match based on a high correlation result. Asynchronous scanning may be used to provide timing information.