Semiconductor Substrate Strain Control via Segmented AlN Layers
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Solution Overview
Problem
The existing semiconductor substrates face issues with crystallinity and strain-related defects due to differences in lattice constant and thermal expansion coefficients between the growth substrate and the compound semiconductor layer, leading to cracks and limitations in the thickness of conductive semiconductor layers in devices like solar cells and light-emitting devices.
Innovation Solution
A semiconductor substrate is designed with a growth substrate, compound semiconductor layers, and control layers comprising multiple nitride semiconductor layers, including Al, to control strain and enhance crystallinity, with the strain control layer formed between the compound semiconductor layers to manage compressive and tensile strains effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single low-temperature AlN layer is grown between the growth substrate and the compound semiconductor layer, then the strain is partially controlled, but the crystallinity and strain control are not yet sufficient
Solution Approach 1:
The single AlN layer is segmented into multiple AlN layers with different thicknesses, arranged in a specific sequence. This segmentation allows each layer to contribute differently to strain control and crystallinity enhancement, resolving the insufficiency of a single uniform layer while maintaining manageable structural complexity.
Solution Approach 2:
The patent creates a composite structure by combining multiple AlN layers of varying thicknesses with the compound semiconductor layer. This composite approach leverages the different properties of each AlN layer to achieve superior strain control and crystallinity compared to a single uniform layer.
2Length of moving object
If the compound semiconductor layer is grown to a great thickness, then the device functionality is enhanced, but cracks occur in the layer due to strain accumulation
Solution Approach 1:
Multiple AlN layers are grown in advance before the compound semiconductor layer to pre-establish a controlled strain environment. This preliminary action creates a favorable foundation that enables subsequent thick compound semiconductor layer growth without crack formation, as the strain is progressively managed through the layered structure.
Solution Approach 2:
The patent changes the parameters of the AlN layers, specifically varying the thickness of different AlN layers in the sequence. This parameter variation allows for progressive strain management, enabling the compound semiconductor layer to grow to greater thicknesses while maintaining structural integrity and preventing cracks.
3Ease of manufacture
If the compound semiconductor layer is grown on the growth substrate, then the device structure is formed, but the difference in lattice constant causes dislocation and deteriorates crystallinity
Solution Approach 1:
Multiple AlN layers serve as intermediary layers between the growth substrate and the compound semiconductor layer. These intermediary layers gradually bridge the lattice constant difference, reducing dislocation formation and preserving crystallinity quality while still enabling device structure formation.
Solution Approach 2:
The patent addresses the two-dimensional lattice mismatch problem by introducing a vertical dimensional solution through multiple stacked AlN layers. Each layer in the vertical sequence progressively manages the lattice constant difference, transforming the single-interface problem into a multi-stage transition that preserves crystallinity.
4Temperature
If the growth substrate and compound semiconductor layer are cooled down to room temperature, then the device operates at ambient conditions, but tensile strain causes the growth substrate to break
Solution Approach 1:
The multiple AlN layers provide a counterbalancing compressive strain effect that offsets the tensile strain developed during cooling to room temperature. This strain counterweight prevents the growth substrate from breaking while still allowing the device to operate at ambient conditions.
Solution Approach 2:
The AlN layers are grown beforehand to create a strain buffer system that cushions against the thermal stress occurring during cooling. This prior cushioning prevents substrate breakage by absorbing and distributing the tensile strain that would otherwise cause failure at room temperature.
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 allows for the growth of thicker conductive semiconductor layers without cracks, improves crystallinity, and prevents substrate breakage by continuously increasing compressive strain, thereby enhancing the performance and yield of electronic devices.
Implementation Method 1
one or more control layers disposed between the compound semiconductor layers, in which each control layer includes a plurality of nitride semiconductor layers including at least Al
Implementation Method 2
one of the plurality of nitride semiconductor layers is doped with a dopant of 0.1 μmol or more
Data Source
AI summary
Provided is a semiconductor substrate including a growth substrate, one or more compound semiconductor layers disposed on the growth substrate, and one or more control layers disposed between the compound semiconductor layers. Each control layer includes multiple nitride semiconductor layers including at least Al.