Gate Electrode Resistance Measurement for HCI Self-Heating
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Solution Overview
Problem
The challenge in predicting the lifetime of MOS transistors under HCI accelerated stress tests is exacerbated by temperature rise due to self-heating, which differs between DC and AC stress conditions, leading to overestimation of HCI lifetime and potential yield reduction in semiconductor products.
Innovation Solution
A gate electrode with contacts at both ends is used for resistance measurement, applying voltages to predict the temperature rise caused by self-heating, allowing for accurate correction of HCI lifetime predictions and preventing excessive degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DC stress is applied for HCI accelerated stress test, then HCI lifetime can be evaluated, but temperature rise due to self-heating causes overestimation of HCI lifetime
Solution Approach 1:
A separate gate electrode for resistance measurement is introduced as an intermediary element. This dedicated gate electrode measures the resistance value to detect temperature rise, allowing the main gate electrode to perform HCI stress testing without being directly affected by temperature measurement interference. The intermediary structure enables independent measurement of temperature effects while maintaining accurate HCI lifetime evaluation.
Solution Approach 2:
The gate electrode for resistance measurement is designed as a copy of the main gate electrode, having the same structure and position relative to the channel. This copied structure experiences the same self-heating effects but is used solely for temperature detection through resistance measurement, enabling accurate temperature rise detection without interfering with the HCI stress test on the main gate.
2Measurement precision
If gate resistance measurement is performed during HCI stress test, then temperature rise can be detected, but additional measurement structure increases device complexity
Solution Approach 1:
The gate electrode for resistance measurement serves multiple functions: it acts as a template for forming the main gate electrode, provides a reference for etching alignment, and functions as a temperature sensor during HCI stress testing. This multi-functional design eliminates the need for separate temperature sensing structures, reducing overall device complexity while maintaining measurement precision.
Solution Approach 2:
The gate electrode for resistance measurement is formed first as a preliminary structure before creating the main gate electrode. This preliminary gate electrode serves as a template that guides the subsequent formation of the main gate, ensuring precise alignment and reducing manufacturing complexity. The preliminary structure is then used for temperature measurement during operation.
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
This method enables precise prediction of temperature rise and HCI lifetime, reducing yield losses by accurately accounting for self-heating effects during DC stress, thereby improving semiconductor product reliability.
Implementation Method 1
temperature rise due to heating caused by a current that flows between the drain and the source at the time of gate ON
Implementation Method 2
measuring a resistance value of the gate electrode for gate resistance measurement (for temperature monitoring)
Data Source
AI summary
To predict a temperature rise amount due to self-heating of a resistance value of a gate electrode with high accuracy in an HCI accelerated stress test. A gate electrode for gate resistance measurement (for temperature monitoring) that has contacts on its both sides, respectively, is disposed adjacent to the gate electrode. At the time of gate ON of the gate electrode, voltages that are substantially the same voltages as that of the gate electrode and have a minute potential difference between its contacts are applied between the contacts of the gate electrode for gate resistance measurement (for temperature monitoring), and a resistance value of the gate electrode for gate resistance measurement (for temperature monitoring) is measured.