Atomic Oxygen Radical Re-oxidation for Gate Oxide Thickness Control
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Solution Overview
Problem
Conventional re-oxidation processes in semiconductor memory devices lead to increased thickness of tunnel oxide and dielectric interlayer patterns due to 'bird's beak' formation, affecting operating speed and threshold voltage uniformity in non-volatile memory devices, especially as feature sizes decrease.
Innovation Solution
Employing a re-oxidation process using atomic oxygen radicals to form oxide layers, which are highly reactive and prevent oxidant infiltration into the central portions of gate structures, thereby minimizing thickness increase and improving oxide quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional re-oxidation process is used to form oxide layers on gate structures, then the oxide layers are formed to compensate for etching damage, but the oxidants diffuse into the central portions of the gate structures causing bird's beak formation and increasing the thickness of tunnel oxide and dielectric interlayer patterns
Solution Approach 1:
The patent changes the chemical parameters of the re-oxidation process by introducing atomic oxygen radicals (O3, O2 plasma) to create a highly reactive oxidizing environment. This parameter change enables rapid oxide formation at the surface without significant diffusion into the central portions of the gate structure, thereby preventing bird's beak formation while maintaining oxide quality
Solution Approach 2:
The patent employs strong oxidants in the form of atomic oxygen radicals generated through ozone (O3) or oxygen plasma treatment. These strong oxidants rapidly form oxide layers on the gate structure surface, compensating for etching damage without requiring prolonged exposure that would cause oxidant diffusion and bird's beak formation
2Productivity
If the line width of gate structures is reduced to increase integration density, then more chips can be fabricated per wafer, but the bird's beak formation becomes more pronounced relative to the gate structure dimensions
Solution Approach 1:
By changing the oxidation mechanism to use atomic oxygen radicals, the patent achieves rapid surface oxidation that is less sensitive to feature size scaling. This allows reduced line widths for higher integration density while maintaining consistent oxide thickness uniformity across the gate structure
3Reliability
If a re-oxidation process is performed to cure damaged surfaces from etching, then the oxide quality is improved, but the programming and erasing threshold voltages become non-uniform across cell gate structures
Solution Approach 1:
The use of atomic oxygen radicals provides rapid and uniform oxide formation across all gate structures. This accelerated oxidation process cures etching damage uniformly without causing variable diffusion into different regions, thereby maintaining consistent threshold voltages across the memory array
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 use of atomic oxygen radicals in the re-oxidation process reduces the thickness increase of tunnel oxide and dielectric interlayer patterns, enhances oxide quality, and achieves more uniform programming and erasing voltages across cell gate structures, improving the performance and reliability of non-volatile memory devices.
Implementation Method 1
a re-oxidation process is performed on the substrate having the preliminary gate structure using an oxygen radical including at least one oxygen atom, so that an oxide layer is formed on a surface of the substrate and sidewalls of the preliminary gate structure
Data Source
AI summary
In an embodiment, a method of forming a gate structure for a semiconductor device includes forming a preliminary gate structure on a semiconductor substrate. The preliminary gate structure includes a gate oxide pattern and a conductive pattern sequentially stacked on the substrate. Then, a re-oxidation process is performed to the substrate having the preliminary gate structure using an oxygen radical including at least one oxygen atom, so that an oxide layer is formed on a surface of the substrate and sidewalls of the preliminary gate structure to form the gate structure for a semiconductor device. The thickness of the gate oxide pattern is prevented from increasing, and the quality of the oxide layer is improved.