Transistor Internal Capacitance Measurement for Switching Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
There is a need to accurately measure the internal capacitances, particularly the first internal capacitance, and the electric charge stored in transistor devices like MOSFETs and IGBTs, as they influence switching characteristics and parasitic-turn-on tendencies, which are crucial for device reliability.
Innovation Solution
A method involving applying a predefined voltage between load path nodes, measuring the voltage across the control node, and using an evaluation circuit to determine the electric charge and capacitance values of the internal capacitances, allowing for wafer-level measurement of multiple devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional measurement methods are used for internal capacitances, then measurement capability is limited, but measurement precision and reliability assessment are insufficient
Solution Approach 1:
The patent introduces an evaluation circuit as an intermediary system that includes a voltage source, measurement circuit, and calculation unit. This intermediary enables indirect measurement of the first internal capacitance by applying voltage between load path nodes and measuring voltage at the control node, then calculating the capacitance value based on the measured data and known second internal capacitance values, thereby overcoming the difficulty of direct measurement
Solution Approach 2:
The patent replaces direct electrical measurement methods with a computational approach. Instead of directly measuring the first internal capacitance through complex electrical probes, the system uses voltage application and measurement followed by mathematical calculation (Q = C×V relationships) to determine capacitance values, substituting direct measurement with a calculation-based method
2Productivity
If wafer-level measurement is implemented for multiple devices, then productivity increases, but measurement system complexity increases
Solution Approach 1:
The evaluation circuit is designed as a universal measurement system that can measure multiple transistor devices simultaneously at the wafer level. The same circuit architecture (voltage source, measurement circuit, calculation unit) serves all devices on the wafer, enabling multi-functionality that increases productivity without requiring separate measurement systems for each device
Solution Approach 2:
The measurement process is segmented into distinct functional modules: voltage application module, voltage measurement module, and capacitance calculation module. This segmentation allows the complex measurement task to be divided into manageable components that can be systematically applied to multiple devices, reducing overall system complexity while enabling wafer-level throughput
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
Enables precise determination of internal capacitances and stored charges, enhancing the understanding of transistor behavior and reliability, particularly in preventing unintended switching and ensuring safe operation.
Implementation Method 1
A first internal capacitance that is effective between the control node and a first load path node... Both the first internal capacitance and the charge stored in the first internal capacitance define the switching characteristic of the transistor devices
Implementation Method 2
A second internal capacitance that is effective between the control node and a second load path node... the second internal capacitance and the charge stored in the second internal capacitance define the switching characteristic
Data Source
Figure 1~3
Figure 4~6
Figure 7~8
AI summary
A method and an evaluation circuit are disclosed. The method includes applying a voltage with a predefined voltage level between a first load path node (11) and a second load path node (12) of a transistor device (1); measuring a voltage between a control node (13) and the second load path node (12) to obtain a voltage measurement value; and determining at least one of an electric charge stored in a first internal capacitance (21) or a capacitance value (C21) of the internal capacitance (21) effective between the first load path node (11) and the control node (13) based on the first voltage measurement value and based on a capacitance value of a second internal capacitance (31) effective between the control node (13) and the second load path node (12).