Semiconductor Device Guard Ring and Protective Diode Design
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Solution Overview
Problem
In semiconductor devices, the resistive SiN film is prone to cracking due to thermal expansion coefficient differences with aluminum electrodes, and is susceptible to corrosion and production tolerance issues, reducing reliability and electrical characteristics.
Innovation Solution
A semiconductor device design where a protective diode is placed above a termination structure region with an insulating film, using diffusion layers and a polyimide surface protective film instead of resistive SiN, to reduce electric field concentration and prevent cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a resistive SiN film is used as a surface protective film, then electric field concentration is reduced, but the film is prone to cracking due to thermal expansion coefficient differences with aluminum electrodes
Solution Approach 1:
The patent changes the material parameter of the surface protective film from resistive SiN to polyimide, which has different thermal expansion characteristics that match aluminum electrodes better, preventing cracking while maintaining protective function
Solution Approach 2:
The patent uses a composite structure with multiple protective films (oxide film and polyimide film) to combine the benefits of different materials - the oxide film provides electrical insulation while the polyimide film provides mechanical protection and thermal expansion compatibility
2Strength
If a resistive SiN film is used as a surface protective film, then breakdown voltage is improved, but the film is susceptible to corrosion and production tolerance issues
Solution Approach 1:
The patent employs a composite protective film structure where an oxide film (providing high breakdown voltage and corrosion resistance) is combined with a polyimide film (providing mechanical protection), thus achieving both electrical performance and environmental stability
Solution Approach 2:
The oxide film acts as an intermediary layer between the semiconductor device and the polyimide film, providing both electrical insulation with high breakdown voltage and chemical corrosion resistance, while the polyimide film provides additional mechanical protection
3Strength
If guard ring regions are provided below the protective diode, then electric field concentration is reduced, but device complexity increases
Solution Approach 1:
The patent merges the protective diode structure with the guard ring regions, where the protective diode is formed directly above the guard rings sharing the same semiconductor substrate, thus reducing overall device complexity while maintaining electric field management benefits
Solution Approach 2:
The guard ring regions serve multiple functions: they provide electric field management to prevent concentration and simultaneously serve as part of the protective diode structure, reducing the need for separate components and simplifying device architecture
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 prevents cracking and corrosion, enhances reliability, and maintains electrical characteristics by reducing electric field concentration on guard ring regions without using resistive SiN film.
Implementation Method 1
A protective diode clamps an overvoltage including an external surge voltage or a noise voltage and a surge voltage, such as electromagnetic noise, to prevent the overvoltage from being applied to the power semiconductor element
Implementation Method 2
A surface protective film that covers the termination structure region is provided. The protective diode includes a plurality of diodes which are formed by alternately arranging first-conductivity-type semiconductor layers and second-conductivity-type semiconductor layers
Implementation Method 3
the resistive SiN film is prone to cracking due to thermal expansion coefficient differences with aluminum electrodes
Data Source
Figure 1(a)~1(b)
Figure 2A
Figure 2B
AI summary
A protective diode (10) is provided above a first guard ring region which surrounds an active region (21), with a field oxide film (9) interposed therebetween. The protective diode (10) includes a series pn zener diode (18) in which a p+ layer (19) and an n- layer (20) are adjacent to each other. In a semiconductor device (100) having the first guard ring region provided below the protective diode (10), since a polyimide film (15) is provided as a surface protective film, it is possible to prevent the occurrence of cracks in the surface protective film. In addition, the first guard ring region is provided below the protective diode (10) and is connected to a second guard ring region that is provided in a portion other than the portion provided below the protective diode (10) through a third guard ring region which is an intermediate region (R). Therefore, when a surge voltage is applied, it is possible to reduce the concentration of the electric field on the outermost guard ring (31e) in the first guard ring region provided below the protective diode (10).