Composite Substrate With Periodic Buffer Layer for Thin FD-SOI
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Solution Overview
Problem
In Fully Depleted Silicon-On-Insulator (FD-SOI) structures, manufacturing a silicon layer with a thin thickness and good crystal quality is challenging due to difficulties in achieving low defect density and preventing cracking.
Innovation Solution
A composite substrate is manufactured by forming a periodic buffer layer on a support substrate, followed by epitaxial growth and bonding to a target substrate, with the support and buffer layers being removed to achieve a stacked structure of the target substrate and epitaxial growth layer, which improves crystal quality and reduces stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a thin silicon layer is manufactured directly on a silicon substrate, then the device parasitic capacitance is reduced, but the crystal quality deteriorates due to high defect density and cracking
Solution Approach 1:
The silicon layer is segmented into multiple thin silicon sublayers separated by insulating layers, allowing each sublayer to be manufactured with acceptable crystal quality while achieving the overall thin thickness effect for reduced parasitic capacitance
Solution Approach 2:
An insulating layer is introduced as an intermediary between the silicon sublayers, serving as both a structural support to prevent cracking and a dielectric to reduce parasitic capacitance, thereby enabling thin silicon layer fabrication with good crystal quality
2Reliability
If the silicon layer thickness is reduced to eliminate floating body effect, then device performance is improved, but manufacturing difficulty increases due to cracking and defect formation
Solution Approach 1:
The thin silicon layer is divided into multiple thinner silicon sublayers, each with sufficient mechanical strength to avoid cracking during manufacturing, while the combined structure still achieves the ultrathin effect needed to eliminate floating body effect
Solution Approach 2:
Insulating layers are pre-positioned between silicon sublayers to provide mechanical support and stress relief before subsequent processing steps, preventing cracking and defect formation during manufacturing
3Manufacturing precision
If a periodic buffer layer structure is introduced, then crystal quality and stress control are improved, but device structure complexity increases
Solution Approach 1:
The buffer layer is segmented into a periodic structure of alternating high-dielectric constant and low-dielectric constant material layers, enabling independent optimization of crystal quality (through stress control) and electrical performance (through capacitance management)
Solution Approach 2:
The periodic buffer layer uses composite material structure with different dielectric constants arranged periodically, providing both mechanical stress control for crystal quality improvement and electrical capacitance control for device performance
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 method allows for the production of a composite substrate with an ultrathin epitaxial growth layer of high crystal quality, addressing the challenges of thinness, crystal quality, and defect density, and eliminating the floating body effect common in Partially Depleted Silicon-On-Insulator (PD-SOI) structures.
Implementation Method 1
The buffer layer has a periodic structure in which a first sublayer and a second sublayer are alternately arranged... improves crystal quality and reduces stress
Implementation Method 2
bonding the epitaxial growth layer on a target substrate of which a surface has a bonding layer
Data Source
AI summary
Disclosed are a composite substrate and a method for manufacturing the same, and a semiconductor device structure. In this application, after a buffer layer and an epitaxial growth layer are sequentially formed on a support substrate, the epitaxial growth layer is bonded on a target substrate of which a surface has a bonding layer, and the support substrate and the buffer layer are removed to form the composite substrate at least including the target substrate, the bonding layer and the epitaxial growth layer which are stacked sequentially, the buffer layer has a periodic structure in which a first sublayer and a second sublayer are alternately arranged. In this application, the buffer layer is provided with the periodic structure, so that a stress may be adjusted, and crystal quality of the epitaxial growth layer may be significantly improved.