Spalled III-V (110) Substrate Surface Morphology Control
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Solution Overview
Problem
The spalling of GaAs substrates with common (100) crystal orientation results in undesirable 'saw-toothed' surfaces with triangular facets, which are not well-suited for depositing semiconductor materials and limit the reliable recovery and reuse of substrates, leading to increased manufacturing costs.
Innovation Solution
A method involving the deposition of device layers onto III-V planar substrates oriented at specific angles, such as the (110) plane, followed by the application of a directional force to separate the device layer from the substrate, resulting in a surface with terraces that are smooth and suitable for regrowth, allowing for the recycling of substrates with minimal surface preparation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spalling is applied to (100) substrate surfaces, then device layers can be removed from substrates, but the substrate surfaces become saw-toothed with triangular facets that are unsuitable for depositing semiconductor materials
Solution Approach 1:
The patent changes the crystallographic orientation parameter of the substrate from the common (100) orientation to a (110) orientation with a specific offcut angle (1-10) between 0.5 and 5 degrees. This parameter change fundamentally alters the spalling behavior, transforming the surface morphology from undesirable saw-toothed facets to smooth terraced surfaces with step heights of 0.5-5 micrometers, which are suitable for subsequent semiconductor material deposition while maintaining substrate reuse capability
2Ease of repair
If spalling is applied to remove device layers, then substrates can be recycled, but the separation process becomes unreliable and requires extensive surface preparation
Solution Approach 1:
By changing the substrate orientation parameter to (110) with a precise offcut angle of 1-10 degrees, the patent creates a reliable and consistent spalling process. The specific offcut orientation promotes uniform crack propagation through the device layers, achieving complete separation with minimal variability. This eliminates the need for extensive surface preparation procedures while ensuring reproducible separation results across multiple substrate reuse cycles
3Ease of manufacture
If common (100) substrate orientation is used, then substrates are readily available, but the spalled surfaces have weak bond energies and are not suitable for further device growth
Solution Approach 1:
The patent changes the substrate orientation parameter from (100) to (110) with a 1-10 degree offcut, transforming the surface morphology into smooth terraced structures. This parameter change creates surfaces with appropriate bond energies and atomic arrangements that are highly suitable for subsequent semiconductor material deposition, while the substrate remains readily available through standard fabrication processes
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 enables the consistent and reliable separation of device layers from substrates, reducing manufacturing costs and maintaining the quality of subsequent device layers grown on recycled substrates, with efficiencies comparable to those grown on new substrates.
Implementation Method 1
applying a directional force orthogonal to the reference plane and moving in a direction that is parallel to the reference plane
Implementation Method 2
Spalling is a method by which device layers deposited onto substrates can be removed from the substrates
Implementation Method 3
depositing a stressor layer onto the device layer
Data Source
AI summary
The present disclosure relates to a composition that includes a III-V planar substrate having a surface aligned with and parallel to a reference plane, where the surface includes a plurality of terraces, each terrace includes a first surface positioned between a first boundary and a second boundary, each boundary is substantially parallel to the other boundaries and positioned substantially parallel to the reference plane, and each terrace is separated from an adjacent terrace by a second surface positioned between the second boundary of the terrace and the first boundary of the adjacent terrace.