Semiconductor Isolator With Trench-Embedded Transformer
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Solution Overview
Problem
Current isolators, such as photocouplers and transformers, face challenges in size reduction, high voltage tolerance, and electrical characteristics due to limitations in coil design and integration with semiconductor substrates, leading to increased DC resistance, parasitic capacitance, and noise susceptibility.
Innovation Solution
The proposed isolator features a transformer configuration with a primary coil embedded in a trench and a secondary coil within an insulating film on a semiconductor substrate, allowing for reduced size, decreased DC resistance, and increased voltage gain, while minimizing parasitic capacitance and coil-induced magnetic effects by positioning the transformer on the substrate's surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If coils are arranged in parallel on semiconductor substrate, then integration is improved, but DC resistance increases and voltage gain decreases
Solution Approach 1:
The patent transitions from planar parallel coil arrangement to a three-dimensional stacked configuration where primary and secondary coils are positioned on opposite surfaces of the semiconductor substrate, connected via conductive vias. This dimensional change reduces the overlap area between coils, thereby reducing parasitic capacitance and improving electrical characteristics while maintaining integration.
Solution Approach 2:
The patent embeds the primary coil within a trench structure and surrounds it with insulating oxide films, creating a nested configuration. The secondary coil is then positioned on the opposite surface, also within a trench. This nested arrangement allows compact integration while maintaining electrical isolation and reducing parasitic effects.
2Area of stationary object
If coils are positioned close together for compact size, then area is reduced, but parasitic capacitance increases
Solution Approach 1:
The patent introduces thick insulating oxide films as intermediary layers between the primary and secondary coils. These oxide films, formed by anodization or deposition processes, provide electrical isolation and reduce parasitic capacitance while allowing the coils to be positioned in close proximity for compact integration.
Solution Approach 2:
By positioning coils on opposite surfaces of the substrate rather than in the same plane, the patent reduces the lateral overlap area between coils. This dimensional separation significantly reduces parasitic capacitance while maintaining compact overall device area.
3Volume of moving object
If transformer is integrated on semiconductor substrate, then size is reduced, but coil-induced magnetic effects increase
Solution Approach 1:
The patent extracts the magnetic core from the transformer structure, creating a coreless transformer configuration. By removing the magnetic body, the patent eliminates magnetic saturation effects and reduces magnetic interference with other circuit elements while maintaining the compact integrated structure on the semiconductor substrate.
4Reliability
If thick insulating film is used for high voltage tolerance, then voltage tolerance is improved, but device area increases
Solution Approach 1:
The patent positions the thick insulating oxide films vertically between coils on opposite substrate surfaces, rather than requiring large lateral spacing. This dimensional arrangement allows high voltage tolerance through thick insulation while maintaining compact device area through efficient three-dimensional space utilization.
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 enables size reduction, improved electrical characteristics, and high voltage tolerance, enhancing the isolator's performance by reducing parasitic capacitance and coil-induced magnetic effects, thus addressing the limitations of existing isolators.
Implementation Method 1
a transformer configured by a primary coil and a secondary coil, wherein the primary coil is electrically coupled to the transmission circuit, the secondary coil is electrically coupled to the reception circuit
Data Source
AI summary
In certain aspects of the invention, an isolator is configured by a reception circuit, a transmission circuit, and a transformer. In some aspects, the transmission circuit is disposed in an anterior surface of a semiconductor substrate. The transformer is disposed in a posterior surface of the semiconductor substrate and transmits in an electrically isolated state to the reception circuit, a signal input from the transmission circuit. The transformer is configured by a primary coil and a secondary coil. The primary coil can be configured by a metal film embedded in an oxide film inside a coil trench. The secondary coil can be disposed inside an insulating film covering the primary coil so as to oppose the primary coil and is insulated from the primary coil by the insulating film.