Semiconductor Device Surge Immunity Vertical Protection
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Solution Overview
Problem
High-side power ICs face challenges in protecting control circuit elements against external surges due to the limited surge immunity of polysilicon diodes per unit area, requiring larger areas for sufficient protection and affecting radiation performance.
Innovation Solution
The semiconductor device incorporates an input-side diode and a vertical protective diode connected between the signal input terminal and the high-potential-side terminal, and between the semiconductor base body and the low-potential-side terminal, respectively, to enhance breakdown current and surge immunity without increasing the diode area, thereby improving radiation performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polysilicon diodes are used as protective elements, then breakdown voltage can be achieved, but surge immunity per unit area is insufficient requiring larger area
Solution Approach 1:
The protective function is divided into two separate elements: an input-side diode connected between the signal input terminal and semiconductor base body, and a vertical protective element connected between the semiconductor base body and low-potential-side terminal. This segmentation allows each element to be optimized for its specific function, with the vertical protective element providing superior surge immunity per unit area compared to traditional polysilicon diodes.
Solution Approach 2:
The patent transitions from using only horizontal polysilicon diodes to incorporating a vertical protective element that exploits the vertical dimension of the semiconductor structure. This vertical configuration enables more efficient use of the semiconductor substrate, achieving higher surge immunity density by utilizing the third dimension (depth) rather than only the planar surface area.
2Reliability
If larger diode area is used to ensure surge immunity, then protective capability is improved, but device size increases
Solution Approach 1:
By segmenting the protective function into two specialized elements (input-side diode and vertical protective element), each element can be minimized in size while maintaining optimal protective performance. The vertical protective element's three-dimensional structure provides high surge immunity density, reducing the overall area required compared to a single large polysilicon diode.
Solution Approach 2:
The patent changes the structural parameter of the protective element from horizontal polysilicon diode to vertical protective element with specific conductivity type configuration. This parameter change enables higher surge immunity per unit area, allowing the protective function to be achieved with smaller overall device size.
3Reliability
If polysilicon diodes are used for protection, then breakdown voltage is achieved, but radiation performance is degraded
Solution Approach 1:
The protective function is segmented into an input-side diode and a vertical protective element with specific conductivity configuration. This segmentation allows the vertical protective element to be designed with optimal doping profiles and structural characteristics that provide both breakdown voltage protection and improved radiation hardness, separating the breakdown function from the radiation-sensitive polysilicon diode structure.
Solution Approach 2:
The patent employs a composite protective structure combining an input-side diode and a vertical protective element with different conductivity types and structural configurations. This composite approach leverages the strengths of each element: the input-side diode for basic protection and the vertical protective element for enhanced breakdown voltage and radiation resistance, achieving superior overall performance.
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 configuration achieves higher surge current absorption capability with a smaller diode area compared to polysilicon diodes, reducing the overall size of the protective elements and enhancing radiation performance.
Implementation Method 1
When an input voltage required for the signal input terminal is high, horizontal diodes having relatively low breakdown voltage are connected in series at multiple stages, and are used as protective elements to increase the breakdown voltage
Data Source
AI summary
A semiconductor device includes: a semiconductor base body of a first conductivity type; a high-potential-side terminal connected to the semiconductor base body; a horizontal control circuit element deposited at an upper part of the semiconductor base body; a signal input terminal connected to a control electrode of the control circuit element; a low-potential-side terminal connected to a main electrode region of the control circuit element; an input-side diode connected in a forward direction between the signal input terminal and the semiconductor base body; and a vertical protective element connected between the semiconductor base body and the low-potential-side terminal.