IGBT Sinker Layer Structure for ESD and Saturation Current
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing semiconductor devices with IGBTs face challenges in enhancing electrostatic discharge (ESD) resistance and reliably operating PNP bipolar transistors due to the proximity of n+ and p+ diffusion layers, which reduces the built-in potential and hinders transistor operation, resulting in reduced saturation currents.
Innovation Solution
A semiconductor device structure is designed with a first conductivity-type high-concentration diffusion layer acting as a collector, a second conductivity-type low-concentration drift layer, and a gate insulating film, along with a sinker layer and interconnects to ensure proper operation of the bipolar transistor by maintaining a floating state for the drift layer and achieving high ESD resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the n+ diffusion layer and p+ diffusion layer are short-circuited by a collector electrode, then the ESD resistance is enhanced, but the saturation current is remarkably reduced due to difficulty in operating the bipolar transistor
Solution Approach 1:
The invention segments the current conduction paths by creating separate lateral and vertical transistor structures. The lateral MOS transistor handles ESD events while the vertical bipolar transistor handles normal current conduction, ensuring that saturation current is not reduced while maintaining ESD protection.
Solution Approach 2:
The gate insulating film and gate electrode act as intermediaries that enable the bipolar transistor to operate properly by controlling the potential distribution. This intermediary structure allows the bipolar transistor to function as intended while the lateral MOS structure provides ESD protection.
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 solution effectively enhances ESD resistance and ensures reliable operation of the bipolar transistor by maintaining the required built-in potential, leading to increased saturation currents and efficient transistor operation.
Implementation Method 1
the product of the resistance R1 of the n− drift layer 430 located under the p+ diffusion layer 432 and the electronic current I1 flowing through the n− drift layer 430 is required to be set to be equal to or more than the built-in potential (for example, about 0.7 V) of a pn diode including the p+ diffusion layer 432 and the n− drift layer 430
Implementation Method 2
a current flows in the longitudinal direction to some extent, which results in an increase in the ESD resistance
Data Source
AI summary
A sinker layer is in contact with a first conductivity-type well, and is separated from a first conductivity-type collector layer and a second conductivity-type drift layer. A second conductivity-type diffusion layer (second second-conductivity-type high-concentration diffusion layer) is formed in the surface layer of the sinker layer. The second conductivity-type diffusion layer has a higher impurity concentration than that of the sinker layer. The second conductivity-type diffusion layer and the first conductivity-type collector layer are isolated from each other with an element isolation insulating film interposed therebetween.