Laser-Induced Hot Carrier Injection for IC Aging
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Solution Overview
Problem
Hot carrier injection (HCI) damage in integrated circuits (ICs) is challenging to reproduce and accelerate effectively in conventional testing methods, leading to unrealistic stress conditions and limited understanding of long-term reliability due to high electric fields and power delivery constraints.
Innovation Solution
A laser-based system using a high-power ultrafast laser to generate hot carriers through multi-photon injection, accelerating HCI aging in ICs at low transistor voltage bias, allowing for rapid and controlled induction of damage equivalent to years of normal use in a short period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional DC testing with increased voltage and current is used to accelerate HCI degradation, then HCI damage can be induced, but unrealistic high temperatures are created within the transistor structure due to DC current self-heating
Solution Approach 1:
The patent replaces electrical stress (DC current) with optical stress (laser radiation) to induce hot carrier injection. The laser system uses photons to generate hot carriers directly in the transistor channel through multi-photon absorption, eliminating the need for high DC currents that cause self-heating. This substitution of the stress mechanism resolves the contradiction by achieving HCI acceleration without thermal damage.
Solution Approach 2:
The patent changes the fundamental parameter of stress application from electrical (voltage/current) to optical (laser power/wavelength). By using laser radiation with specific wavelengths and pulse durations, hot carriers are generated through optical absorption rather than electrical conduction, thereby avoiding the thermal effects associated with high DC currents while still achieving the desired HCI degradation.
2Productivity
If supply rail voltages are significantly increased to accelerate HCI degradation in packaged ICs, then HCI aging can be accelerated, but power supply or thermal diode malfunction occurs which becomes the main reliability limiter
Solution Approach 1:
The patent substitutes electrical over-stress with optical stress to accelerate aging. The laser-induced hot carrier injection mechanism allows for rapid aging accumulation without requiring voltage increases that would push the device beyond its operational limits. The laser parameters (power, wavelength, pulse duration) can be precisely controlled to induce degradation while keeping the device within safe electrical operating conditions.
Solution Approach 2:
The laser acts as an intermediary that indirectly induces HCI damage without requiring direct electrical over-stress. Instead of applying high voltages that cause immediate failure or malfunction, the laser radiation serves as a mediator that generates hot carriers through optical absorption, achieving aging acceleration while maintaining normal electrical operating conditions.
3Loss of information
If extended operation outside intended use conditions is performed to collect HCI aging data, then more aging data can be collected, but other effects (power supply or thermal diode malfunction) become the main reliability limiter before meaningful HCI aging data can be collected
Solution Approach 1:
The patent replaces electrical stress conditions with optical stress conditions to eliminate secondary failure modes. By using laser radiation to induce hot carrier injection, the method avoids the activation of other reliability-limiting mechanisms such as power supply malfunction or thermal diode failure that occur under extended electrical over-stress. This allows for clean isolation of HCI degradation effects.
Solution Approach 2:
The laser-induced hot carrier injection performs the aging acceleration action in advance without requiring extended operation under risky conditions. The method achieves significant aging in short time periods under controlled laser parameters, preventing the onset of secondary failure modes before meaningful data can be collected.
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 laser-assisted method enables precise and efficient acceleration of HCI aging, avoiding electrical stress issues and thermal damage, allowing for the rapid evaluation of IC reliability and prediction of lifetime degradation.
Implementation Method 1
A laser source is used to generate a population of hot carriers within an electric field of a transistor through a multi-photon carrier injection mechanism
Data Source
AI summary
Laser-assisted integrated circuit (IC) device testing apparatus capable of inducing hot carrier injection (HCI) within selected transistors of an IC device. A laser source of sufficiently high output power (e.g., 1W) and short pulse duration (e.g., 100 fs) can generate enough hot carriers through a multi-photon (e.g., TPA) carrier injection mechanism to significantly accelerate HCI aging even at low transistor voltage bias (e.g., <1.5V). Rapid laser-assisted HCI transistor aging can selectively degrade transistors of individual functional IC blocks within an IC device.