Laser Circuit Testing Signal Accumulation
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Solution Overview
Problem
Conventional laser-induced techniques for integrated circuit testing face reduced detection sensitivity due to lower laser coupling efficiency with advanced circuits, and increasing laser power risks damage, while using pulsed lasers with lock-in amplifiers is difficult to calibrate and implement in real-time testing.
Innovation Solution
A method and apparatus that radiate a laser beam onto an electronic circuit, accumulate response signal samples, and generate test results using a signal processor, without requiring increased laser power or the use of a lock-in amplifier, allowing for improved detection sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the power of the laser beam is increased to compensate for reduced laser coupling efficiency, then the detection sensitivity is improved, but the risk of laser induced damage to the integrated circuit increases
Solution Approach 1:
The patent applies periodic action by using a pulsed laser beam instead of a continuous laser beam. The laser is pulsed at a frequency between 1 Hz and 1000 Hz, which allows the circuit to cool down between pulses, preventing thermal damage while maintaining detection sensitivity through signal accumulation during the pulsing cycle.
Solution Approach 2:
The patent implements continuity of useful action by accumulating multiple signal samples taken during the pulsing period. This accumulation process continues over many cycles, building up the useful signal while the pulsed nature prevents harmful thermal effects, thus maintaining continuous detection capability without damage.
2Measurement precision
If a pulsed laser with lock-in amplifier is used to improve detection sensitivity, then the noise level is reduced, but the complexity of calibration and control increases
Solution Approach 1:
The patent extracts and eliminates the lock-in amplifier from the system, replacing it with a simpler signal accumulation approach implemented in software or digital processing. This removes the complex calibration and control requirements of the lock-in amplifier while maintaining the ability to process pulsed laser signals effectively.
Solution Approach 2:
The patent substitutes the analog lock-in amplifier mechanism with a digital signal accumulation process. Instead of using analog phase-sensitive detection requiring precise frequency and phase matching, the system uses digital sampling and accumulation of voltage samples, which is simpler to implement and control.
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
The approach enhances detection sensitivity for integrated circuit testing without risking damage from high laser power and simplifies the process by eliminating the need for lock-in amplifier calibration, making it suitable for real-time testing.
Implementation Method 1
using a scanned laser beam, typically in the infrared frequency range, to stimulate integrated circuit failures which are sensitive to thermal or carrier stimulations
Implementation Method 2
Thermal Induced Voltage Alteration (TIVA), Thermal Beam Induced Phenomenon (TBIP)
Implementation Method 3
Optical Beam Induced Resistance Change (OBIRCH), Differential Resistance Measurement (DReM)
Data Source
AI summary
A method of testing an electronic circuit is provided. The method comprises radiating a laser beam onto the electronic circuit, and determining a plurality of samples of a response signal output by the electronic circuit during the period when the laser beam is radiated. The method further comprises accumulating the plurality of samples to generate a value, and generating a test result based on the value.