Nitride Semiconductor Defect Layer for Dislocation Termination
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Solution Overview
Problem
Existing semiconductor devices with nitride semiconductor substrates face significant dislocation issues due to lattice constant mismatches, leading to suboptimal performance, as previous methods like ion implantation do not adequately terminate dislocations, resulting in residual dislocations in the epitaxial layers.
Innovation Solution
A semiconductor device structure incorporating a defect layer with a high defect density of 5×10^17 cm^-2 over the epitaxially grown layer, where dislocations are terminated or looped without reaching the surface, reducing dislocation density in the second epitaxial layer, achieved by ion implantation and careful defect layer formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ion implantation is performed to terminate dislocations, then the number of dislocations is reduced, but a substantial number of dangling bonds remain and dislocations still penetrate through to the second layer
Solution Approach 1:
The patent changes the parameters of ion implantation by using multiple stages with different ion types, energies, and doses. The first implantation uses 20 keV ions at 1×10^13 cm^-2, followed by a second implantation with higher energy ions. This multi-stage parameter adjustment creates a defect layer with optimal properties that effectively terminates dislocations without allowing penetration.
Solution Approach 2:
The patent introduces an intermediary defect layer between the first and second epitaxial layers. This defect layer, created by controlled ion implantation, acts as a mediator that intercepts and terminates dislocations before they can reach the second layer, while still allowing beneficial strain effects to pass through.
2Manufacturing precision
If high defect density is created to terminate dislocations, then dislocation termination improves, but complete amorphization occurs which hinders epitaxial growth
Solution Approach 1:
The patent precisely controls ion implantation parameters (energy, dose, ion type) to create a defect layer with optimal defect density. This parameter optimization ensures sufficient defects to terminate dislocations while maintaining enough crystalline order to support subsequent epitaxial growth of the second layer.
Solution Approach 2:
The patent applies partial amorphization rather than complete amorphization. The ion implantation creates enough defects to terminate dislocations but stops short of complete amorphization, leaving sufficient crystalline structure to enable epitaxial regrowth of the second layer over the defect layer.
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 effectively reduces dislocation density in the second epitaxial layer, enhancing crystallinity and performance by looping dislocations within the defect layer, while avoiding complete amorphization that would hinder epitaxial growth.
Implementation Method 1
an interface layer formed over the first nitride semiconductor layer, the interface layer having an interface layer density of 1×10^19 atoms/cm² or more and 1×10^22 atoms/cm² or less, wherein dislocations formed in the first nitride semiconductor layer are terminated at the interface layer
Implementation Method 2
ions are implanted into the first nitride semiconductor layer. At this time, ions are implanted to the extent that the first nitride semiconductor layer is not amorphized
Implementation Method 3
a first nitride semiconductor layer is epitaxially grown over a sapphire substrate. Next, ions are implanted into the first nitride semiconductor layer. Subsequently, a second nitride semiconductor layer is epitaxially grown over the first nitride semiconductor layer
Data Source
AI summary
A second epitaxial layer is grown epitaxially over a first epitaxial layer. The first epitaxial layer includes an epitaxially grown layer and a defect layer. The defect layer is disposed over the epitaxially grown layer and serves as a surface layer of the first epitaxial layer. The defect density of the defect layer is 5×1017 cm−2 or more. Defects penetrating through the defect layer form loops in the second epitaxial layer.