ESD Element Heat Dispersion via Electric Field Relaxation Layer
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Solution Overview
Problem
Existing semiconductor devices face challenges in achieving high electrostatic discharge (ESD) immunity while maintaining a small size, as they tend to generate local heat, which can lead to melting and destruction of the ESD element, and increasing the size to enhance driving ability compromises resistance and functionality.
Innovation Solution
The introduction of an electric field relaxation layer with an intermediate impurity concentration between the n+ collector layer and the n-type well layer helps disperse heat, reducing maximum heat generation temperature and enhancing ESD immunity without increasing the size of the ESD element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sectional area of the ESD element is increased to enhance driving ability and suppress local heat generation, then the ESD immunity is improved, but the size of the ESD element increases
Solution Approach 1:
The patent applies local quality by creating an electric field relaxation layer with intermediate impurity concentration specifically at the heat generation area between the n+ collector layer and the n-type well layer. This localized modification of impurity concentration in a specific region allows the ESD element to suppress local heat generation without requiring an overall increase in the sectional area of the entire ESD element, thus resolving the contradiction between ESD immunity and device size.
2Strength
If the distance from the heat generation area to the collector contact region is extended to prevent electrode melting, then the collector electrode is protected, but the size and resistance of the n+ collector layer increase
Solution Approach 1:
The patent introduces an electric field relaxation layer as an intermediary between the n+ collector layer and the n-type well layer. This intermediate layer with moderate impurity concentration acts as a mediator that reduces the electric field strength at the critical interface, thereby suppressing local heat generation and protecting the collector electrode from thermal damage without requiring extension of the collector contact region distance, thus avoiding increased size and resistance.
3Reliability
If a high resistance N-well electric field relaxation layer is used to improve withstanding voltage, then the breakdown voltage is enhanced, but local heat generation occurs due to charge accumulation
Solution Approach 1:
The patent applies parameter changes by modifying the impurity concentration parameter of the electric field relaxation layer. Instead of using a high resistance (highly doped) N-well layer that causes charge accumulation and local heat generation, the patent uses a layer with intermediate impurity concentration. This parameter adjustment reduces the electric field strength at the interface while maintaining adequate withstanding voltage, thereby suppressing local heat generation without sacrificing voltage protection capability.
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 approach effectively suppresses local heat generation, improving ESD immunity by distributing heat generation areas and reducing the maximum heat generation temperature, thereby allowing for a smaller ESD element design without compromising driving ability.
Implementation Method 1
The generated heat is conducted to a collector contact region 1 to melt the collector electrode 7
Implementation Method 2
electric charges tend to accumulate in the n+ collector layer 2, and the electric field becomes strong to locally generate heat
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Provided is a semiconductor device comprising: a PW layer formed at a surface of a semiconductor substrate; an NW layer formed at the surface of the semiconductor substrate to be in contact with the PW layer; a p+ base layer formed at the surface of the semiconductor substrate in the PW layer; an n+ collector layer formed at the surface of the semiconductor substrate in the NW layer; an n+ emitter layer located between the p+ base layer and the n+ collector layer and formed at the surface of the semiconductor substrate in the PW layer; and an n± layer formed between the n+ collector layer and the PW layer to be in contact with the n+ collector layer.