Hybrid Substrate Defect Trapping Zone via Insulator Roughening
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Solution Overview
Problem
The existing processes for fabricating hybrid substrates in the field of optics and electronics often result in surface defects on the semiconductor active layer due to the build-up of gaseous elements at bonding interfaces, particularly when the active layer thickness is small, and the use of intermediate layers can alter electrical properties.
Innovation Solution
A process involving the formation of a roughened insulator layer surface to create a trapping zone, which retains gaseous species and reduces surface defects, without the need for additional intermediate layers, by using chemical etching or gas plasma treatments to achieve a minimum RMS roughness of 10 nm and ensuring the insulator layer is at least 10 times thicker than the roughness, and implementing atomic species implantation to form a zone of weakness for detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a smooth insulator layer surface is used in conventional fabrication processes, then the bonding interface quality is maintained, but gaseous elements accumulate at the interface causing surface defects on the active layer
Solution Approach 1:
The insulator layer surface is deliberately roughened to create a porous structure with increased surface area and volume. This porous structure acts as a trapping zone that absorbs and retains gaseous elements (such as hydrogen and helium from ion implantation, and water vapor) preventing their accumulation at the bonding interface and subsequent formation of defects on the active layer surface.
Solution Approach 2:
The roughened insulator layer surface acts as an intermediary trapping zone between the bonding interface and the active layer. This intermediate porous structure captures gaseous elements before they can reach the bonding interface, thereby protecting the active layer from defect formation while maintaining the integrity of the bonding process.
2Reliability
If intermediate layers are added to prevent defect formation, then surface defects are reduced, but the electrical properties of the substrate are altered
Solution Approach 1:
Instead of adding intermediate layers throughout the structure, the invention applies local quality modification only at the insulator layer surface through roughening treatment. This creates a trapping zone precisely where gaseous elements accumulate, without introducing additional layers that would affect the electrical properties of the substrate. The roughened surface provides the necessary defect prevention function locally without global structural modification.
3Length of moving object
If the active layer thickness is reduced to achieve miniaturization, then device size is decreased, but the number of surface defects increases
Solution Approach 1:
The insulator layer surface is roughened in advance before bonding and ion implantation processes. This preliminary action creates a trapping zone that is ready to capture gaseous elements during subsequent processing steps. By preparing this trapping structure beforehand, the method prevents defect formation even in thin active layers where defects would be more visible and problematic, thereby enabling miniaturization without sacrificing surface quality.
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 minimizes surface defects on the transferred active layer, even with thin layers, and maintains the electrical properties of the substrate, as the trapping zone retains gaseous species and prevents defect formation, enhancing the quality of the hybrid substrate.
Implementation Method 1
forming a roughened surface on the first insulator layer... the roughened surface forms a trapping zone that is capable of retaining gaseous atomic species
Implementation Method 2
implantation of atomic species into the donor substrate so as to form a zone of weakness therein
Implementation Method 3
using chemical etching or gas plasma treatments to achieve a minimum RMS roughness of 10 nm
Implementation Method 4
using chemical etching or gas plasma treatments to achieve a minimum RMS roughness of 10 nm
Implementation Method 5
bonding a second substrate, called a 'receiver substrate', onto the free surface of the insulator by molecular adhesion
Data Source
AI summary
A process for fabricating a hybrid substrate that has a defect trapping zone. The process includes the steps of forming or depositing a first insulator layer on a first substrate of semiconductor material; increasing roughness of the first insulator layer surface; depositing a second insulator layer on the roughened surface of the first insulator to form a trapping zone between the layers; bonding a second substrate onto the second insulator layer by molecular adhesion; and transferring an active layer formed by the implantation of atomic species into one of the substrates. The trapping zone is able to retain gaseous species present at the various interfaces of the hybrid substrate to limit the formation of defects on the surface of the active layer that is transferred.