Electrostatic Protection Element Thyristor Structure Integration
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Solution Overview
Problem
Conventional electrostatic protection elements for high breakdown voltage semiconductor elements require additional processing steps and increased costs due to the need for deep high-concentration diffusion layers, which are not suitable for manufacturing both high and low breakdown voltage semiconductor elements on the same substrate.
Innovation Solution
An electrostatic protection element with a thyristor structure is designed, featuring impurity layers with specific conductivity types and concentrations, allowing for shared impurity profiles and processes with high and low breakdown voltage semiconductor elements, eliminating the need for special processing steps and reducing the protection element's area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a deep high-concentration N-type diffusion layer is formed in the collector contact region to improve holding voltage, then the holding voltage is improved, but additional processing steps and increased costs are required
Solution Approach 1:
The invention merges the electrostatic protection element with the high breakdown voltage semiconductor element by forming the deep high-concentration N-type diffusion layer (fourth impurity layer) that serves dual purposes: improving the holding voltage of the protection element and forming the N-type well layer of the high breakdown voltage element. This integration eliminates additional processing steps and reduces manufacturing costs.
Solution Approach 2:
The deep high-concentration N-type diffusion layer is designed to perform multiple functions simultaneously: it acts as part of the thyristor structure for electrostatic protection (improving holding voltage) and as the N-type well layer for the high breakdown voltage semiconductor element. This multi-functionality resolves the contradiction by making the same structure serve both protection and device formation purposes.
2Reliability
If a deep high-concentration diffusion layer is used to protect high breakdown voltage elements, then protection effectiveness is improved, but the device area increases
Solution Approach 1:
The invention combines the electrostatic protection element and the high breakdown voltage semiconductor element into a single integrated structure. The deep high-concentration N-type diffusion layer is shared between both elements, allowing the protection function to be achieved without increasing the overall device area, as the protection element and the protected element occupy the same physical space.
3Ease of manufacture
If the same impurity profile is used for both high and low breakdown voltage semiconductor elements, then manufacturing complexity is reduced, but the holding voltage of the protection element becomes too low
Solution Approach 1:
The invention applies local quality by forming the deep high-concentration N-type diffusion layer (fourth impurity layer) with higher impurity concentration than the standard N-type well layer. This localized high-concentration region is specifically positioned in the collector contact region to improve the holding voltage of the electrostatic protection element, while the rest of the N-type well layer maintains the appropriate concentration for the high breakdown voltage element. This local modification allows both manufacturing simplicity and adequate holding voltage to be achieved.
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 solution enables effective protection of high breakdown voltage semiconductor elements without additional processing, maintaining a smaller area and reducing manufacturing costs, while ensuring the protection element's operating voltage is within the safe limits of the internal circuit.
Implementation Method 1
When the electrostatic protection element is composed of the same constituent elements as those of the internal element comprising the internal circuit... an NPN bipolar transistor and a thyristor structure are variously proposed... the holding voltage Vh (collector emitter junction breakdown voltage (BVCEO) in the base opened state) in the snapback characteristic
Data Source
AI summary
An electrostatic protection element relating to the present invention comprises a P-type semiconductor and an N-type first impurity layer provided in the semiconductor substrate. The first impurity layer comprises a P-type second impurity layer functioning as a gate. The second impurity layer comprises an N-type third impurity layer functioning as a cathode. Further, the first impurity layer comprises an N-type fourth impurity layer spaced apart from the second impurity layer at a distance. The fourth impurity layer comprises a P-type fifth impurity layer functioning as an anode and an N-type sixth impurity layer. Then, in the electrostatic protection element, an impurity concentration of the fourth impurity layer is higher than that of the first impurity layer, and a bottom of the fourth impurity layer is deeper than that of the second impurity layer.