Recessed Growth Substrate Structure for Lower RF Loss
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Solution Overview
Problem
RF loss in radio frequency devices leads to decreased linearity, primarily due to parasitic circuits formed in the substrate that disturb RF signals, especially as frequency increases.
Innovation Solution
A semiconductor structure is designed with a supporting substrate, buried layer, growth substrate, and buffer layer stacked sequentially, featuring recesses on the growth substrate that are filled by the buffer layer through epitaxial lateral overgrowth, reducing dislocation density and improving crystal quality to minimize RF loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional substrate structure is used without recesses, then the device structure is simple, but parasitic circuits are formed that increase RF loss and reduce linearity
Solution Approach 1:
The substrate surface is segmented by forming multiple recesses that divide the continuous substrate into separated regions. This segmentation prevents the formation of parasitic circuits by electrically isolating different areas, thereby reducing RF loss while maintaining a relatively simple overall structure.
Solution Approach 2:
The recesses are strategically positioned in specific local regions of the substrate where parasitic circuits are most problematic. By modifying only these local areas rather than the entire substrate, the solution reduces RF loss in critical regions while minimizing the added structural complexity.
2Manufacturing precision
If the buffer layer does not completely cover the growth substrate surface, then the manufacturing process is simpler, but dislocation density increases and crystal quality deteriorates
Solution Approach 1:
The buffer layer is grown to completely cover the growth substrate surface, including the sidewalls of the recesses, before subsequent device fabrication steps. This preliminary complete coverage prevents dislocation propagation and ensures high crystal quality from the outset, establishing a solid foundation for later manufacturing steps.
Solution Approach 2:
The buffer layer growth extends into the third dimension by completely filling and covering the recesses, transforming the surface coverage from a two-dimensional planar layer to a three-dimensional conformal layer that wraps around the recess structures. This dimensional extension ensures complete dislocation blocking while maintaining manufacturability through standard epitaxial processes.
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 semiconductor structure effectively blocks parasitic circuits, reducing RF loss and enhancing device characteristics such as electron mobility, breakdown voltage, and leakage current, thereby improving the linearity of RF devices.
Implementation Method 1
a growth substrate, a buffer layer... featuring recesses on the growth substrate that are filled by the buffer layer through epitaxial lateral overgrowth
Data Source
AI summary
A semiconductor structure includes a supporting substrate, a buried layer, a growth substrate, a buffer layer, and a heterojunction structure layer that are sequentially stacked; a plurality of recesses are disposed on a side, away from the supporting substrate, of the growth substrate, and the buffer layer completely covers a surface of the growth substrate. In the present disclosure, the recesses are disposed in the growth substrate, so that a parasitic circuit formed in the growth substrate caused by a radio frequency signal may be blocked, to reduce a disturbance effect of the growth substrate, thereby reducing an RF loss; and the buffer layer is formed, by using epitaxial lateral overgrowth, in the recesses of the growth substrate, so that dislocation density in an epitaxial layer may be greatly reduced, to improve crystal quality, thereby improving characteristics such as electron mobility, breakdown voltage, and leakage current of a device.