SOI Wafer Membrane-Cavity Oxidation for Uniform Device Layers
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Solution Overview
Problem
Current SOI wafer manufacturing processes are complex, expensive, and result in non-uniform device layer thickness and weak bonding strength between the base layer and insulating layer, leading to high import dependence and limited domestic production capabilities.
Innovation Solution
A method involving etching, annealing, and oxidation to form a membrane-cavity structure with a buried oxide layer and outer oxide layers, which simplifies the process, improves bonding strength, and allows for uniform device layer thickness adjustment, eliminating the need for complex ion implantation and bonding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ion implantation or bonding process is used to manufacture SOI wafer, then the insulating layer can be formed, but the bonding strength between base layer and insulating layer is weak
Solution Approach 1:
The patent replaces mechanical bonding processes with a chemical oxidation process. An oxide layer is formed on the inner surface of the cavity through oxidation, creating strong chemical bonding between the insulating layer and base layer, thereby eliminating the need for separate bonding steps and improving bonding strength.
Solution Approach 2:
The patent changes the approach from physical bonding to chemical formation by controlling oxidation parameters. By adjusting oxidation conditions (temperature, time, atmosphere), the oxide layer thickness and bonding strength are optimized, achieving strong adhesion without complex bonding processes.
2Manufacturing precision
If thinning, splitting, and polishing processes are used, then the device layer can be separated, but the thickness uniformity of the device layer is limited
Solution Approach 1:
The patent performs preliminary oxidation to form the oxide layer on the cavity inner surface before device layer separation. This preliminary action ensures that the insulating layer is already in place with uniform thickness, eliminating the need for subsequent thinning and polishing processes, thereby improving both thickness uniformity and manufacturing efficiency.
Solution Approach 2:
The patent replaces mechanical thinning, splitting, and polishing processes with a chemical oxidation approach. The oxide layer is formed uniformly on the cavity surface through oxidation, providing consistent thickness without mechanical intervention, thus improving manufacturing precision and efficiency.
3Ease of manufacture
If complex manufacturing processes are used, then the insulating layer can be formed, but the manufacturing cost is very high
Solution Approach 1:
The patent merges the insulating layer formation process with the cavity formation process. The oxide layer is formed on the inner surface of the cavity during the same manufacturing cycle, combining multiple functions into a single process step, thereby simplifying manufacturing while ensuring reliable bonding.
Solution Approach 2:
The patent replaces complex mechanical bonding processes with a simple oxidation process. By forming the oxide layer through oxidation during cavity formation, the manufacturing process is simplified while achieving strong bonding, thus improving ease of manufacture without compromising reliability.
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 reduces manufacturing time, enhances bonding strength, and achieves uniform device layer thickness, making the process more efficient and cost-effective, while also applicable to germanium-on-insulator wafers, thereby reducing import dependence and improving domestic production capabilities.
Implementation Method 1
forming a membrane-cavity structure by performing an annealing process on the wafer
Implementation Method 2
forming a membrane-cavity structure by performing an annealing process on the wafer, the membrane-cavity structure including a cavity corresponding to the hole array
Implementation Method 3
forming a buried oxide layer on an inside of the cavity and a first outer oxide layer on an outside of the membrane
Data Source
AI summary
A SOI wafer is formed by forming a hole array on a surface of a wafer including a semiconductor material, forming a membrane-cavity structure by annealing process on the wafer, forming a buried oxide layer on an inside of the cavity and an outer oxide layer on an outside of the membrane, and forming a device layer by removing the outer oxide layer.