Hybrid Multilayer Device Trench Isolation
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Solution Overview
Problem
Heteroepitaxial growth of III-V compound semiconductors on silicon substrates often results in detrimental defects such as threading dislocations due to lattice and thermal mismatch, which can reduce the performance and lifespan of microelectronic systems.
Innovation Solution
A hybrid multilayer device is fabricated using a substrate with a trench, where a first layer of III-V compound semiconductor is bonded to the substrate using a wafer bonding process, creating a free-standing, defect-free region for the optically active layer within the trench boundaries, thereby isolating it from interfacial defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If heteroepitaxial growth of III-V compound semiconductors is performed directly on a Si substrate, then integration of optical gain materials on silicon is achieved, but threading dislocations and other defects occur due to lattice and thermal mismatch
Solution Approach 1:
The device is segmented into distinct regions: a Si substrate, a bonding interface region with a trench, and a free-standing III-V layer region. The trench physically separates the bonding interface from the optically active region, allowing defects to be confined to the interface while the active region remains defect-free. This segmentation enables direct integration of III-V materials on Si while preventing defect propagation to the optical gain region.
2Reliability
If a trench structure is introduced to isolate the optically active region, then defects are eliminated from the active region, but device structure complexity increases
Solution Approach 1:
The harmful bonding interface region containing defects is extracted and isolated from the optically active region through the trench structure. By removing the defective region from proximity to the active region, the patent achieves defect-free operation while maintaining a relatively simple overall device architecture. The trench acts as a physical barrier that extracts defects from the functional region.
3Ease of manufacture
If wafer bonding process is used to bond the first layer to the substrate, then heteroepitaxial growth is enabled, but interfacial defects are generated at the bonding interface
Solution Approach 1:
The trench structure serves as an intermediary barrier between the bonding interface and the optically active region. It allows the wafer bonding process to proceed for ease of manufacture while simultaneously preventing the harmful interfacial defects generated during bonding from affecting the optical gain region. The trench mediates between the manufacturing requirement for bonding and the performance requirement for defect-free active regions.
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 substantially eliminates defects associated with lattice and thermal mismatch, enabling high-quality heteroepitaxy and maintaining device performance by confining injected carriers to a defect-free region within the trench, allowing for efficient photon emission and operation of photonic devices.
Implementation Method 1
a first layer of III-V compound semiconductor is bonded to the substrate using a wafer bonding process
Data Source
AI summary
A multilayer device includes a substrate and a first layer disposed on the substrate. A trench extends through one or both of the substrate and the first layer. The trench has a first sidewall spaced apart from a second sidewall, each sidewall extending from an upper surface of the substrate to a lower surface of the first layer. An optically active region is disposed on the first layer overlying the trench, such that at least a portion of the optically active region is located within a set of lines corresponding to the sidewalls of the trench.