Semiconductor Device Region Isolation Structure
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Solution Overview
Problem
The existing region isolation structure in semiconductor devices, as disclosed in Patent Document 1, suffers from leakage current paths that form parasitic npn transistors, leading to inadequate region isolation performance and potential device malfunctions or noise due to the potential relationship among different portions of the semiconductor substrate.
Innovation Solution
A semiconductor device configuration with a region isolation structure extending from the front surface of a second semiconductor layer to a first semiconductor layer, where the first semiconductor layer has a higher conductivity type impurity concentration, effectively isolating device regions operating on different reference voltages by allowing carrier recombination and suppressing leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a p-type isolation layer is used to separate device regions, then region separation is achieved, but leakage current paths form parasitic npn transistors that reduce isolation performance
Solution Approach 1:
The patent changes the impurity concentration parameter of the semiconductor layer, creating a high-impurity-concentration region (first conductivity type) within the isolation structure. This parameter change transforms the isolation mechanism from relying solely on potential relationships to utilizing carrier recombination in the high-impurity region, thereby suppressing leakage current and eliminating parasitic transistor effects.
2Adaptability or versatility
If device regions operate on different reference voltages, then functional differentiation is achieved, but potential relationship issues cause malfunction or noise
Solution Approach 1:
The patent introduces an intermediary structure - the region isolation structure with a high-impurity-concentration semiconductor layer - that mediates between device regions operating on different reference voltages. This intermediary layer provides a controlled transition zone where carriers recombine, preventing direct interaction between different voltage domains and eliminating noise and malfunction issues.
3Length of stationary object
If the region isolation structure extends to the semiconductor substrate, then isolation depth is increased, but parasitic npn transistor formation is not prevented
Solution Approach 1:
The patent applies local quality by creating a high-impurity-concentration region specifically at the isolation structure location, rather than uniformly throughout the entire semiconductor layer. This localized modification of impurity concentration at the isolation region provides effective leakage current suppression without requiring the isolation structure to extend through the entire substrate depth.
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 enhances region isolation performance, improving device properties by preventing leakage current and ensuring reliable operation of device regions with different reference voltages.
Implementation Method 1
carriers entering the first semiconductor layer from the second semiconductor layer are lost due to recombination in the first semiconductor layer
Data Source
AI summary
A semiconductor device includes a semiconductor substrate of a first conductivity type, a first semiconductor layer of the first conductivity type formed on the semiconductor substrate and having a first conductivity type impurity concentration higher than that of the semiconductor substrate, a second semiconductor layer of a second conductivity type formed above the first semiconductor layer, a first device region formed in the second semiconductor layer and configured to operate based on a first reference voltage, a second device region formed in the second semiconductor layer and configured to operate based on a second reference voltage, the second device region being spaced apart from the first device region, and a region isolation structure interposed between the first and second device regions and formed in a region extending from a front surface of the second semiconductor layer to the first semiconductor layer so as to electrically isolate the first and second device regions from each other.