Semiconductor Device Plasma Induced Damage Measurement
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Solution Overview
Problem
Current methods for measuring the effect of plasma-induced damage (PID) on the threshold voltage of transistors in semiconductor devices are inefficient, leading to inaccurate results and difficulties in scaling down the test element group (TEG) area, which hinders precise measurement and reliable operation of semiconductor devices.
Innovation Solution
Incorporating a measuring transistor connected to an antenna part and a switch transistor that controls the connection between the measuring transistor and a ring oscillator, allowing for accurate measurement of PID effects by monitoring oscillation frequency differences, thereby minimizing PID impact on diffusion layers and enabling precise characterization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pads are connected to the gates, sources, and drains of the MOSFETs and to the substrate terminals for direct threshold voltage measurement, then measurement accuracy is improved, but the area per device under test increases making it difficult to arrange a test element group in a semiconductor chip
Solution Approach 1:
The patent introduces a ring oscillator as an intermediary device to indirectly measure the threshold voltage of MOSFETs. Instead of directly measuring threshold voltage which requires large pads, the invention converts the threshold voltage information into oscillation frequency through the ring oscillator circuit. This intermediary approach allows accurate measurement without requiring large connection pads, thus resolving the contradiction between measurement accuracy and area consumption.
2Area of stationary object
If multiple device under tests are connected in parallel in the ring oscillator structure, then the area per device under test is reduced, but it becomes difficult to accurately measure the PID effect on threshold voltage
Solution Approach 1:
The patent segments the measurement function by providing separate dedicated connection paths for each MOSFET's gate to the ring oscillator, while maintaining individual control over each device. This segmentation allows multiple MOSFETs to be tested in parallel with reduced area per device, while still enabling accurate individual measurement of PID effects through separate gate connections and controlled switching mechanisms.
Solution Approach 2:
The patent introduces dynamic control elements (switches) that allow selective activation of individual MOSFETs in the parallel configuration. By dynamically controlling which MOSFET is active at any given time, the system can accurately measure PID effects on individual devices even though multiple devices are physically present in a compact parallel arrangement, thus resolving the contradiction between area reduction and measurement accuracy.
Data Source
AI summary
Provided is a semiconductor device, a measurement device, a measurement method, and a semiconductor system that enable accurate measurement of the plasma induced damage (PID) effect on a small scale. The semiconductor device includes an NMOSFET whose gate is connected to an antenna part that functions as an antenna in a plasma process and a PMOSFET that controls the connection between the NMOSFET and a ring oscillator. The semiconductor device is provided with a test element group (TEG) that includes an NMOSFET whose gate is connected to an antenna part that functions as an antenna in a plasma process and a PMOSFET that controls the connection between the NMOSFET and a ring oscillator.