SOI Device Layer Clean-and-Etch for Cleave Damage Removal
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Solution Overview
Problem
Existing methods for preparing semiconductor-on-insulator (SOI) structures result in surface roughness and thickness uniformity issues due to cleaving, leading to increased manufacturing costs and yield loss, as conventional cleaning and smoothing processes fail to achieve optimal results.
Innovation Solution
A clean-and-etch operation using an alkaline solution and optional oxidizing agents at controlled temperatures and durations to remove damaged regions from the cleaved semiconductor layer, followed by thermal annealing or epitaxial smoothing, eliminating the need for additional layer thinning steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cleaning and smoothing processes (SC1/SC2 clean, thermal annealing, chemical mechanical polishing) are used after cleaving, then particles and contaminants are removed, but surface roughness and thickness uniformity remain suboptimal
Solution Approach 1:
The patent performs the clean-and-etch operation immediately after cleaving while the damaged region is still present and accessible. By removing the damaged region early in the process before subsequent manufacturing steps, the invention prevents surface roughness and thickness uniformity issues from developing, rather than attempting to correct them later.
Solution Approach 2:
The patent uses an alkaline solution with specific pH and temperature parameters to chemically etch and remove the damaged region. By controlling the chemical parameters (alkaline solution concentration, temperature, exposure time), the process achieves optimal surface roughness and thickness uniformity that conventional cleaning methods cannot attain.
2Manufacturing precision
If additional smoothing processes (thermal annealing, chemical mechanical polishing) are performed to improve surface quality, then surface roughness may be reduced, but manufacturing cycle time and costs increase
Solution Approach 1:
The patent combines the cleaning function and the damaged region removal function into a single clean-and-etch operation using an alkaline solution. This merged process eliminates the need for separate smoothing steps (thermal annealing, chemical mechanical polishing) that would otherwise be required, thereby reducing manufacturing cycle time and costs while achieving superior surface quality.
Solution Approach 2:
The patent converts the harmful damaged region created by cleaving into a beneficial feature by using the damaged region's increased reactivity to the alkaline solution. The damaged region etches more readily, allowing the clean-and-etch process to selectively remove only the damaged portion while leaving the undamaged device layer intact, achieving surface smoothing without additional processing steps.
3Ease of manufacture
If the damaged region is not removed after cleaving, then manufacturing steps are simplified, but the cleaved surface attracts particles and contaminants due to dangling bonds
Solution Approach 1:
The patent extracts and removes the damaged region containing the reactive dangling bonds from the device layer. By selectively removing only the damaged surface layer through the clean-and-etch operation, the invention eliminates the source of particle and contaminant attraction while preserving the intact device layer beneath, thus preventing contamination without complicating the manufacturing process.
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
The method reduces surface roughness and defectivity, minimizing manufacturing cycle time and costs by directly addressing imperfections in the cleaved surface, thereby enhancing the quality and efficiency of SOI structure production.
Implementation Method 1
removing the damaged region from the single crystal semiconductor device layer of the cleaved structure using a clean-and-etch operation that includes contacting the exposed surface of the single crystal semiconductor device layer with an alkaline solution
Implementation Method 2
A clean-and-etch operation using an alkaline solution and optional oxidizing agents at controlled temperatures and durations to remove damaged regions from the cleaved semiconductor layer
Implementation Method 3
followed by thermal annealing or epitaxial smoothing
Implementation Method 4
followed by thermal annealing or epitaxial smoothing
Data Source
AI summary
A method of preparing a semiconductor-on-insulator structure from a bonded structure including a handle substrate, a donor substrate including a cleave plane, and a dielectric layer positioned between the handle substrate and the donor substrate, the method includes cleaving the bonded structure at the cleave plane to form a cleaved structure including the handle substrate, the dielectric layer, and a device layer. The single crystal semiconductor device layer defines a damaged region at an exposed surface opposite the dielectric layer. The damaged region includes single crystal semiconductor material and extends a thickness from the exposed surface. The method also includes removing the damaged region from the cleaved structure using a clean-and-etch operation that includes contacting the exposed surface of the device layer with an alkaline solution at a temperature and for a duration sufficient to remove the damaged region and smoothing the device layer with the damaged region removed.