Multi-regional Epitaxial Growth for Substrate Reuse
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Solution Overview
Problem
The high cost of non-silicon substrates with lattice constants matching functional semiconductors limits the development of electronic and photonic devices, and existing layer-transfer techniques have disadvantages that hinder their widespread use.
Innovation Solution
A method involving the growth of multiple single-crystalline layers with etch stop layers allows for the reuse of substrates by sequentially removing and exposing underlying layers for further growth, enabling the continuous use of substrates even when terminal layers become unsuitable, and allowing different types of single-crystalline materials to be grown using the same substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-silicon substrates with lattice constants matching functional semiconductors are used, then epitaxial growth of thicker layers without defects is enabled, but the cost increases significantly
Solution Approach 1:
The substrate system is segmented into multiple functional layers: a low-cost silicon substrate, a lattice-matched buffer layer, and optional intermediate layers. This segmentation allows the expensive lattice-matched material to be used only where necessary (in the buffer layer) rather than for the entire substrate, reducing overall cost while maintaining defect-free growth capability.
Solution Approach 2:
The patent implements a nested structure where a lattice-matched buffer layer is grown on top of a silicon substrate, creating a hierarchical arrangement. This nested configuration allows the silicon substrate to provide mechanical support while the buffer layer provides the necessary lattice match, combining the advantages of both materials.
2Ease of manufacture
If layer-transfer techniques are used to reduce substrate cost, then substrate reuse is enabled, but the process complexity and limitations increase
Solution Approach 1:
The lattice-matched buffer layer is grown in advance on the silicon substrate before the actual device layers are fabricated. This preliminary action prepares the substrate in advance with the necessary lattice-matched surface, eliminating the need for complex post-growth transfer operations and simplifying the overall process.
Solution Approach 2:
The lattice-matched buffer layer acts as an intermediary between the silicon substrate and the functional device layers. It mediates the lattice mismatch issue, allowing direct growth of device layers on silicon without requiring complex transfer techniques, thus reducing process complexity.
3Duration of action of stationary object
If a single substrate is used for multiple growth cycles, then substrate lifespan is extended, but contamination and defect accumulation occur
Solution Approach 1:
The lattice-matched buffer layer is designed to be removable after serving its purpose. Once device layers are grown on the silicon substrate through the buffer, the buffer layer can be selectively removed (taken out) to recover the silicon substrate for reuse, while the device layers are transferred or harvested separately, preventing contamination accumulation.
Solution Approach 2:
The patent implements a discard-and-recover strategy where the lattice-matched buffer layer is discarded after use, and the expensive silicon substrate is recovered for reuse. This selective discarding of the sacrificial buffer layer maintains substrate lifespan while preserving growth quality on the reusable silicon substrate.
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 reduces the cost of substrate reuse, extends the lifespan of substrates, and enables the growth of various single-crystalline materials on a single substrate, overcoming the limitations of traditional layer-transfer techniques.
Implementation Method 1
growing a first single-crystalline material over a stack comprising a two-dimensional (2D) material, a first single-crystalline underlayer below the 2D material, a first etch stop layer below the first single-crystalline underlayer, and a second single-crystalline underlayer below first etch stop layer, such that the first single-crystalline material is substantially epitaxially matched to the first single-crystalline underlayer below the 2D material and/or epitaxially matched to the 2D material
Data Source
AI summary
Epitaxial growth of materials, and related systems and articles, are generally described.