Silicon Dangling Bond Passivation via Oxygen Ion Diffusion
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Solution Overview
Problem
The existing CMOS image sensor fabrication process fails to effectively bond dangling bonds of silicon atoms at the silicon interface, leading to increased white pixels and reduced device performance due to the lack of a source for bonding these unsaturated bonds.
Innovation Solution
A method involving surface oxidation to form a silicon oxide layer, followed by the deposition of a dielectric and protective layer, and an oxygen-enriched oxidation treatment, culminating in high-temperature annealing to bond unsaturated silicon atom bonds with oxygen ions, thereby improving the bonding of dangling bonds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fabrication process is used, then manufacturing simplicity is maintained, but dangling bonds of silicon atoms remain unbonded leading to increased white pixels
Solution Approach 1:
The method performs preliminary oxidation to form a silicon oxide layer before subsequent processing steps. This preliminary action creates a foundation that enables effective dangling bond bonding in later annealing steps, resolving the contradiction by preparing the structure in advance rather than attempting to bond dangling bonds directly without proper preparation.
Solution Approach 2:
The patent introduces oxygen ions as an intermediary substance that mediates the bonding process. The oxygen ions diffuse through the dielectric layer and bond with silicon atoms at the interface, serving as a mediator that enables bonding without requiring direct contact or complex mechanical processes, thus improving reliability while maintaining process simplicity.
2Reliability
If no oxygen source is provided, then process simplicity is maintained, but dangling bonds cannot be bonded resulting in poor device performance
Solution Approach 1:
The patent employs oxygen-enriched oxidation treatment using strong oxidants to accelerate the bonding process. By providing a concentrated oxygen source that actively diffuses through the dielectric layer, the method achieves effective dangling bond bonding without requiring excessively complex process steps, thus improving bonding efficiency while keeping manufacturing relatively simple.
Solution Approach 2:
The method changes the oxygen concentration parameter by introducing oxygen-enriched environments during specific processing steps. This parameter change enables effective bonding by increasing the availability of oxygen ions without fundamentally altering the overall process architecture, resolving the contradiction between bonding efficiency and manufacturing ease.
3Reliability
If high-temperature annealing is applied, then dangling bond bonding is improved, but energy consumption and process complexity increase
Solution Approach 1:
The patent integrates the oxidation and annealing processes in a continuous manner, where the oxygen-enriched oxidation treatment is followed immediately by annealing without interrupting the thermal processing sequence. This continuity allows the useful action of oxygen diffusion and bond formation to proceed without interruption, improving interface bonding quality while optimizing energy utilization by avoiding repeated heating and cooling cycles.
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 the number of white pixels by 15 to 20% by effectively bonding dangling bonds, enhancing the performance of CMOS image sensors.
Implementation Method 1
oxygen ions in the oxidizing gas penetrate the dielectric layer to reach the wafer surface
Implementation Method 2
After the high-temperature annealing treatment, the unsaturated bonds of silicon atoms are bonded to the oxygen ions on the wafer surface
Implementation Method 3
after high-temperature annealing treatment, the unsaturated bonds of silicon atoms are bonded to the oxygen ions
Data Source
AI summary
The invention discloses a method for improving bonding of dangling bonds of silicon atoms. A surface of a wafer is oxidized to form a silicon oxide layer. The upper surface of the silicon oxide layer has a dangling bond. A dielectric layer is disposed on the upper surface of the silicon oxide layer, which is then subjected to an oxygen-enriched oxidation treatment at a preset first temperature. A protective layer is disposed on the upper surface of the dielectric layer. The wafer is then subjected to an annealing treatment. By passing oxidizing gas through the surface of the protective layer, oxygen ions in the oxidizing gas penetrate the dielectric layer to reach wafer surface. After high-temperature annealing treatment, the unsaturated bonds of the silicon atoms are bonded to the oxygen ions on the wafer surface, thereby improving the bonding of the dangling bonds on the wafer surface.