SOI Substrate High Resistance Layer Eddy Current Reduction
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Solution Overview
Problem
In semiconductor devices with optical waveguides, propagation loss due to light leakage and eddy currents generated by electric signals in the substrate hinder efficient signal transmission, particularly at high frequencies.
Innovation Solution
A semiconductor device configuration with a substrate having a low resistance semiconductor layer and a high resistance semiconductor layer, where the high resistance layer is formed by ion-implanting n-type impurities into the surface of a p-type Si substrate, reducing eddy current interference and improving signal transmission characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a thick insulating layer (SOI substrate) is used to cover the lower side of the optical waveguide, then propagation loss due to light leakage is reduced, but eddy currents are generated in the substrate by electric signals, disturbing signal propagation
Solution Approach 1:
The substrate is divided into two distinct semiconductor layers: a first semiconductor layer and a second semiconductor layer. This segmentation allows each layer to serve different functions - the first layer provides mechanical support while the second layer with higher resistance minimizes eddy current generation, thus resolving the contradiction between reducing propagation loss and preventing eddy current interference.
Solution Approach 2:
The second semiconductor layer is specifically designed with higher resistance than the first semiconductor layer. This local quality change (increased resistance in the second layer)针对性地 addresses the eddy current problem in the region where electric signals are propagated, while maintaining the overall structural integrity and optical waveguide functionality.
2Object-generated harmful factors
If the substrate resistance is reduced to improve electrical conductivity, then eddy current effects are minimized, but signal propagation is disturbed by magnetic field interactions
Solution Approach 1:
The resistance parameter of the second semiconductor layer is specifically increased relative to the first semiconductor layer. This parameter change (higher resistance) directly reduces eddy current effects while the layered structure maintains signal propagation reliability by confining eddy currents to specific regions and providing magnetic field shielding.
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 configuration effectively reduces propagation loss and eddy current effects, enhancing the transmission characteristics of electric signals, especially at high frequencies, by minimizing magnetic field interactions with the wiring.
Implementation Method 1
an eddy current is generated in the substrate by a mutual interaction between the electric signal and the lower layer substrate
Implementation Method 2
an eddy current is generated in the substrate by a mutual interaction between the electric signal and the lower layer substrate
Implementation Method 3
apart of light propagated in the optical waveguide is propagated while leaking around in a region of approximately a wavelength
Data Source
AI summary
Provided is an SOI substrate which has a substrate, an insulating layer formed over the substrate, and a semiconductor layer formed over the insulating layer. Optical waveguides are formed in the semiconductor layer of the SOI substrate. This substrate has a low resistance semiconductor layer and a high resistance semiconductor layer thereover. Further, wirings which are formed through insulating films are provided on the optical waveguides. In this manner, the low resistance semiconductor layer is arranged in the surface part of the substrate of the insulating films, thereby restraining an eddy current generated in the substrate due to an electric signal transmitted through the wirings.