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 bonding to a handle substrate, removal of the sacrificial substrate, and recrystallization of an etch stop layer 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 simple and well-established, but the manufacturing cost is high and the silicon layer thickness uniformity is poor
Solution Approach 1:
The method performs preliminary actions by forming the oxide layer and etch stop layer on the sacrificial substrate before bonding to the handle substrate. This preliminary structuring enables precise thickness control of the silicon layer during subsequent processing steps, resolving the thickness uniformity issue while maintaining process manageability
Solution Approach 2:
The patent introduces an oxide layer and etch stop layer as intermediary structures between the silicon layer and the sacrificial substrate. These intermediary layers serve as etch barriers and thickness reference planes, enabling precise control of silicon layer thickness and improving manufacturing precision without significantly complicating the overall process
2Ease of manufacture
If conventional SOI substrate fabrication is used, then the process is established, but the manufacturing cost is expensive
Solution Approach 1:
The method employs a sacrificial substrate that is intentionally designed to be consumed during the process. This disposable sacrificial substrate enables cost-effective production by allowing the use of simpler, less expensive materials and processes for the temporary substrate, which is removed after serving its purpose of supporting the silicon layer formation
Solution Approach 2:
The patent utilizes parameter changes in the etching process by adjusting etch selectivity between different layers. By controlling etch parameters such as chemical composition and temperature, the method achieves precise thickness control of the silicon layer while using cost-effective processing techniques, thereby improving manufacturing precision without increasing cost
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 enables the cost-effective production of SOI substrates with improved uniformity and quality, enhancing performance characteristics such as speed, packing density, and reduced power consumption.
Implementation Method 1
an oxide layer is formed on a top of the epitaxial layer
Implementation Method 2
the sacrificial substrate is bonded to a handle substrate at the oxide layer
Implementation Method 3
an etch stop layer is recrystallized
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.