SOI Substrate Formation with Etch-Stop Thickness Control
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Solution Overview
Problem
Conventional silicon-on-insulator (SOI) CMOS device fabrication is expensive and unable to provide a uniform thickness of the silicon layer, limiting performance and efficiency.
Innovation Solution
A method involving the formation of an epitaxial layer and an oxide layer on a sacrificial substrate, followed by ion implantation to create an etch stop layer, bonding to a handle substrate, and subsequent removal and recrystallization processes to achieve a high-quality SOI substrate with uniform silicon thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional techniques are used to fabricate SOI substrates, then the process is simpler and faster, but the cost increases and the silicon layer thickness uniformity deteriorates
Solution Approach 1:
An etch stop layer is formed within the silicon layer before the silicon is transferred to the final substrate. This preliminary structure enables precise thickness control during subsequent etching processes, ensuring uniform silicon layer thickness in the final SOI substrate while managing fabrication complexity through planned process steps.
2Productivity
If conventional SOI substrate fabrication is used, then the process is faster, but the manufacturing cost increases
Solution Approach 1:
The method uses a sacrificial substrate as a template or copy holder, where the silicon layer and etch stop layer are formed and then transferred to the final handle substrate. This copying approach enables parallel processing and optimization of individual steps, improving overall fabrication speed while reducing material waste and manufacturing costs.
Solution Approach 2:
The invention employs ion implantation to modify the physical and chemical parameters of the silicon layer, creating an etch stop layer with distinct etching characteristics. This parameter change enables selective removal of sacrificial substrate material while preserving the silicon layer, improving fabrication efficiency and reducing costs through selective etching 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 reduces costs and achieves high-quality, uniformly thick silicon layers, enhancing performance and reducing defects, thereby enabling improved CMOS device fabrication.
Implementation Method 1
an etch stop layer is formed in the epitaxial layer
Implementation Method 2
The sacrificial substrate is bonded to a handle substrate at the oxide layer
Implementation Method 3
subsequent removal and recrystallization processes to achieve a high-quality SOI substrate with uniform silicon thickness
Data Source
AI summary
Methods of forming SOI substrates are disclosed. In some embodiments, an epitaxial layer and an oxide layer are formed on a sacrificial substrate. An etch stop layer is formed in the epitaxial layer. The sacrificial substrate is bonded to a handle substrate at the oxide layer. The sacrificial substrate is removed. The epitaxial layer is partially removed until the etch stop layer is exposed.