Amorphous SiO2 Interlayer for III-N Semiconductor Stress Mitigation
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Solution Overview
Problem
The formation of amorphous silicon oxide between a silicon substrate and III-N semiconductor layers is challenging due to lattice constant mismatch and thermal expansion differences, leading to residual stress and structural defects, and existing methods for forming this layer are inefficient and difficult to control, especially when trying to integrate a uniform amorphous silicon oxide layer between single-crystal rare earth oxide layers.
Innovation Solution
A method involving the deposition of a first single-crystal rare earth oxide layer on a silicon substrate, followed by a uniform layer of amorphous silicon, and then a second rare earth oxide layer, where the temperature is ramped for epitaxial growth to crystallize the amorphous silicon and transfer the lattice constant, allowing for oxidation to form a uniform amorphous silicon oxide layer that mitigates stress and enables efficient growth of III-N semiconductor layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxidation is performed to form amorphous silicon oxide layer, then stress relief is achieved, but the oxidation process is diffusion limited and becomes slower with increasing thickness, making it difficult to form a uniformly thick layer
Solution Approach 1:
A silicon-containing layer is deposited beforehand on the substrate before oxide formation. This preliminary layer serves as the source material for subsequent oxidation, allowing the oxide thickness to be controlled by the initial deposition thickness rather than by the slow diffusion-limited oxidation process, thereby achieving uniform thick oxide layers efficiently
Solution Approach 2:
The patent changes the physical state and source of silicon material from relying on diffusion from the substrate to using a deposited silicon-containing layer as the oxidation source. This parameter change transforms the oxidation process from being diffusion-limited to being deposition-controlled, enabling faster and more uniform oxide layer formation
2Reliability
If rare earth oxide buffer layer is grown on silicon substrate, then stress is reduced to manageable level, but the process requires high oxygen pressure which deteriorates MBE component lifetime
Solution Approach 1:
An amorphous silicon oxide layer is introduced as an intermediary between the silicon substrate and the rare earth oxide buffer layer. This intermediate layer modifies the interface properties and stress distribution, allowing the REO buffer to achieve stress management functionality without requiring the high oxygen pressures that would damage MBE components
3Reliability
If amorphous silicon oxide layer is formed thick enough for stress relief, then stress mitigation is adequate, but the oxidation process takes long time and requires high temperature and pressure
Solution Approach 1:
The silicon-containing layer is deposited in advance with the desired thickness for stress relief. This preliminary deposition establishes the final oxide thickness before oxidation begins, eliminating the need for prolonged oxidation times and high temperature/pressure conditions that would be required to grow thick oxide layers through diffusion-limited oxidation
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 approach allows for controlled formation of a thick, uniform amorphous silicon oxide layer that effectively reduces stress and facilitates the growth of single-crystal III-N semiconductor layers on silicon substrates, improving the electric breakdown characteristics and structural integrity of electronic and photonic devices.
Implementation Method 1
The crystalline silicon is oxidized to transform the crystalline silicon to amorphous silicon
Implementation Method 2
the temperature required for epitaxial growth crystallizes the layer of amorphous silicon to form a layer of crystallized silicon
Data Source
AI summary
A method of forming a REO dielectric layer and a layer of a-Si between a III-N layer and a silicon substrate. The method includes depositing single crystal REO on the substrate. The single crystal REO has a lattice constant adjacent the substrate matching the lattice constant of the substrate and a lattice constant matching a selected III-N material adjacent an upper surface. A uniform layer of a-Si is formed on the REO. A second layer of REO is deposited on the layer of a-Si with the temperature required for epitaxial growth crystallizing the layer of a-Si and the crystallized silicon being transformed to amorphous silicon after transferring the lattice constant of the selected III-N material of the first layer of REO to the second layer of REO, and a single crystal layer of the selected III-N material deposited on the second layer of REO.