Thick GaN-on-Silicon Growth With Deformation Compensation Layers
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Solution Overview
Problem
The epitaxial growth of thick gallium nitride (GaN) layers on silicon substrates is challenging due to thermal expansion mismatch and material lattice mismatch, leading to deformation, cracks, and potential damage.
Innovation Solution
A method involving the application of deformation compensation layers, such as SiO2, SiNxO, SiN, SiC, and Al2O3, along with buffer layers like AlN and AlxGa1-xN, and stress estimation during growth to mitigate deformation, using temperature and thickness adjustments based on epitaxial, interface, and thermal stress calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If thick GaN layers are grown on Si substrates, then the semiconductor layer thickness is increased, but thermal expansion mismatch and material lattice mismatch cause deformation and cracks
Solution Approach 1:
The patent applies preliminary action by depositing deformation compensation layers (such as SiO2, SiNxO, SiN, SiC, Al2O3, or Cr2O3) on the Si substrate before growing the thick GaN layer. These compensation layers are specifically designed to pre-compensate for the thermal expansion mismatch and material lattice mismatch that will occur during GaN growth, thereby preventing deformation and cracks in the final thick GaN layer while maintaining substrate integrity
2Reliability
If buffer layers are added to mitigate deformation, then the manufacturing process complexity increases, but deformation is reduced
Solution Approach 1:
The patent applies parameter changes by systematically varying the thickness, material composition, and deposition temperature of the deformation compensation layers. By optimizing these parameters, the patent achieves effective deformation control while managing the complexity of the multi-layer structure. The compensation layers are designed with specific thickness ranges and material compositions to provide the necessary stress compensation without excessive structural complexity
3Manufacturing precision
If stress estimation and temperature adjustment are implemented, then the manufacturing process time increases, but manufacturing precision is improved
Solution Approach 1:
The patent applies feedback by implementing stress estimation calculations during the growth process and adjusting deposition parameters based on these estimates. The method calculates epitaxial growth stress, interface stress, and thermal stress, then uses this feedback information to optimize the thickness and temperature parameters of subsequent layers, thereby achieving precise deformation control while managing process time through targeted adjustments rather than exhaustive optimization
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 method enables the growth of GaN layers up to 1000 μm thick on silicon substrates without detrimental deformation or cracks, maintaining performance by ensuring deformation is below the substrate's plastic limit.
Implementation Method 1
epitaxial growth of thick GaN, such as a GaN layer having a thickness ranging from a few micrometers (m) to tens of micrometers (m), on Si is very challenging due to thermal expansion mismatch and material lattice mismatch
Implementation Method 2
thermal expansion mismatch and material lattice mismatch can cause deformation, which may be larger than the Si substrate plastic deformation limitation
Data Source
AI summary
A method of manufacturing a structure for power electronics which includes epitaxially growing a GaN semiconductor layer is provided. The method includes growing buffer layers formed of AlN and AlxGa(1-x)N, wherein 0<x<1, on a Si substrate before growing the semiconductor layer on the buffer layers. The method also includes growing deformation compensation layers formed of SiO2, SiCxN(1-x), SiN, SiCxO(1-x), SiC, SiNxO(1-x), Al2O3, and/or Cr2O3, wherein 0<x<1, on the substrate opposite the semiconductor layer. The deformation compensation layers compensate for deformation of the structure that occurs while growing the semiconductor and buffer layers and deformation that occurs while cooling the structure. The method further includes estimating epitaxial growth stress, interface stress, and thermal stress of the structure, and adjusting the temperature and or thickness of the layers based on the estimated epitaxial growth stress, interface stress, and/or thermal stress.