Epitaxial Substrate Inclination Angle for Al-Based Semiconductor Defect Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing epitaxial growth technologies for III-V compound semiconductor layers, such as InP, face issues with surface defects other than hillock defects, particularly when growing Al-based compound semiconductor layers, which are not effectively addressed by previous methods that focused on off angles and dislocation densities.
Innovation Solution
A substrate with a crystal surface inclined at a specific off angle (0.10 to 0.2°) relative to the (100) plane and a shift angle (β) less than 35° in directions like [0-11], [01-1], [011], or [0-1-1] is used for epitaxial growth, reducing surface defects distinct from hillock defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a substrate with off angle of 0.1 to 0.2° from (100) direction is used for epitaxial growth, then hillock defects are reduced, but surface defects other than hillocks (elongated needle-like defects) still occur on Al-based compound semiconductor layers
Solution Approach 1:
The invention introduces a new parameter (inclination direction angle β) in addition to the existing off angle parameter. By changing the inclination direction to be within ±35° from the <011> direction while maintaining the off angle of 0.1-0.2°, the patent successfully suppresses the elongated needle-like surface defects that occur on Al-based compound semiconductor layers, while preserving the hillock defect reduction benefit
Solution Approach 2:
The patent transitions from considering only the off angle magnitude (one-dimensional parameter) to considering both the off angle magnitude and the inclination direction angle (two-dimensional parameter space). This dimensional expansion allows simultaneous optimization for different defect types by navigating the expanded parameter space
2Object-affected harmful factors
If the off angle of substrate is increased to prevent orange peels, then wrinkle defects are reduced, but hillock defects increase on the surface of epitaxial layer
Solution Approach 1:
The invention changes the parameter configuration by introducing the inclination direction angle β as a new control variable. By setting the inclination direction within ±35° from the <011> direction and maintaining a small off angle of 0.1-0.2°, the patent achieves a balance that prevents both orange peel/wrinkle defects and hillock defects, resolving the trade-off between these two types of surface defects
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 significantly reduces surface defects other than hillock defects, resulting in high-quality epitaxial layers, particularly for Al-based compound semiconductor layers like InAlAs, by optimizing the substrate's inclination and off angles during MOCVD growth.
Implementation Method 1
a compound semiconductor layer is epitaxially grown on an InP substrate
Implementation Method 2
an epitaxial layer composed of this compound semiconductor is formed by, for example, a metal organic chemical vapor deposition method (hereinafter, referred to as an MOCVD method)
Data Source
Figure 1
Figure 2~3
AI summary
It is to provide a substrate for growing a semiconductor, which is effective for suppressing an occurrence of surface defects different in type from hillock defects in case of epitaxially growing a compound semiconductor layer, particularly an Al-based compound semiconductor layer. In a substrate for growing a compound semiconductor, in which a crystal surface inclined at a predetermined off angle with respect to a (100) plane is a principal plane, an angle made by a direction of a vector obtained by projecting a normal vector of the principal plane on the (100) plane and one direction of a [0-11] direction, a [01-1] direction, a [011] direction and a [0-1-1] direction is set to be less than 35°, and the compound semiconductor layer is epitaxially grown on the substrate.