Semiconductor Isolation for Back-EMF Free Carrier Control
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Solution Overview
Problem
Conventional semiconductor integrated circuit devices experience malfunctions due to back electromotive force generated during the ON to OFF transition of motor drivers, causing free carriers to flow into control devices and leading to incorrect signal transmission and motor operation interference.
Innovation Solution
The semiconductor integrated circuit device employs a semiconductor layer divided into island regions with single-conductivity-type and opposite-conductivity-type embedded diffusion regions, where the single-conductivity-type region has a supply potential and separates the control device from the substrate, while the opposite-conductivity-type region is grounded and closer to the surface, attracting and preventing the flow of free carriers generated by the back electromotive force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional motor driver circuit is used without isolation structures, then the circuit structure is simple, but free carriers generated by back electromotive force flow into the control device causing malfunction
Solution Approach 1:
The semiconductor layer is divided into multiple isolated island regions by dividing regions. The control device is placed in a separate island region from the motor driver, preventing free carriers generated during motor operation from reaching the control device. This spatial segmentation ensures reliable control device operation while maintaining a manageable structural complexity through systematic region division.
2Area of stationary object
If the control device is placed close to the driver device for compact design, then the device area is reduced, but free carriers can flow from the driver device to the control device through the substrate
Solution Approach 1:
Even though the overall semiconductor layer area is minimized for compact design, the control device and driver device are placed in separate island regions that are electrically isolated from each other. This segmentation prevents free carriers generated in the driver device region from flowing into the control device region through the substrate, thus eliminating harmful interference while maintaining compact dimensions.
Solution Approach 2:
The substrate acts as an intermediary barrier between the driver device and control device in adjacent island regions. By utilizing the substrate's inherent properties and the isolation structures, free carriers are prevented from crossing from the driver region to the control region, enabling compact placement without compromising device reliability.
3Reliability
If protective diodes are added to dissipate back electromotive force, then the driver device is protected, but free carriers are still generated and can flow to the control device
Solution Approach 1:
The harmful effect of free carriers generated by back electromotive force is extracted and isolated from the control device by placing the driver device and control device in separate island regions. The protective diodes continue to dissipate back electromotive force as intended, while the spatial separation ensures that the free carriers generated during this process cannot reach the control device, thus eliminating the harmful effect without compromising driver protection.
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 effectively prevents malfunctions by isolating the control device from free carriers, ensuring correct operation of the driver device and maintaining normal motor operation by attracting and containing the free carriers within the embedded diffusion regions.
Implementation Method 1
The free carriers (electrons) are attracted through the single-conductivity-type embedded diffusion region
Data Source
AI summary
A semiconductor integrated circuit device according to the present invention includes an N-type embedded diffusion region between a substrate and an epitaxial layer in first and second island regions serving as small signal section. The N-type embedded diffusion region connects to N-type diffusion regions having supply potential. The substrate and the epitaxial layer are thus partitioned by the N-type embedded diffusion region having supply potential in the island regions serving as small signal section. This structure prevents the inflow of free carriers (electrons) generated from a power NPN transistor due to the back electromotive force of the motor into the small signal section, thus preventing the malfunction of the small signal section.