Semiconductor Electrostatic Protection Device Series Elements
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Solution Overview
Problem
Conventional semiconductor devices with high breakdown voltage transistors and electrostatic protection elements are limited by the large area required for PN junctions, making them bulky and difficult to miniaturize.
Innovation Solution
The semiconductor device incorporates a series connection of electrostatic protection elements with a low concentration N-type diffusion layer formed over a P-type semiconductor substrate, reducing the area occupied by the electrostatic protection circuit and allowing for a smaller device size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrostatic protection elements with PN junctions are used, then effective protection against surge voltages is achieved, but the device area becomes large
Solution Approach 1:
The patent divides a single high-breakdown-voltage electrostatic protection element into multiple lower-breakdown-voltage elements connected in series. Each element has a smaller diffusion layer area, and their combined breakdown voltage equals that of the original single element, thus reducing total device area while maintaining protection effectiveness.
Solution Approach 2:
The patent changes the breakdown voltage parameter distribution by using multiple elements with lower individual breakdown voltages instead of one element with high breakdown voltage. This parameter transformation allows each element to have smaller diffusion layers, reducing the overall area occupied by the protection circuit.
2Reliability
If the area of PN junction is increased to prevent destruction, then reliability of protection element is improved, but the device size increases
Solution Approach 1:
The patent segments the protection function across multiple elements, each with smaller PN junction areas. The series connection ensures that the sum of their breakdown voltages provides the required protection level, achieving reliability without requiring large individual junction areas.
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 design achieves a smaller semiconductor device size while maintaining effective protection against surge voltages, with the sum of breakdown voltage values of the electrostatic protection elements equal to the high breakdown voltage transistor, preventing damage from surge currents.
Implementation Method 1
the area of the PN junction E must be large. However, in the present invention, the low concentration N type diffusion layer 36 is formed on the P type semiconductor substrate 35 substantially all over, and thus the area between the low concentration N type diffusion layer 36 and the P type semiconductor substrate 35 is sufficiently large
Data Source
AI summary
A semiconductor device is disclosed. The semiconductor device includes an internal circuit having a high breakdown voltage transistor, and a first electrostatic protection circuit in which electrostatic protection elements are connected in series. The sum of the breakdown voltage values of the electrostatic protection elements in the first electrostatic protection circuit is almost equal to the breakdown voltage value of the high breakdown voltage transistor. The first electrostatic protection circuit is connected between an input/output terminal and a ground terminal of the semiconductor device to which terminals the internal circuit is connected.