Isolation Trench Liner Oxidation for Uniform Memory Etching
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Solution Overview
Problem
In the manufacturing process of memory devices, unintended bumps often form on mask layers due to the differing etch rates between oxide material and liner, which can distort the designed pattern.
Innovation Solution
A method involving the oxidation of a liner in the isolation structure, resulting in oxidized and unoxidized lining portions, which allows for similar etching rates with the oxide layer, thereby reducing the formation of unintended bumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If oxide material and liner are used in isolation trenches, then isolation structure is formed, but unintended bumps appear on mask layers due to etch rate difference between oxide material and liner
Solution Approach 1:
The liner is oxidized to change its material composition from oxygen-free to oxidized state, which modifies its etch rate to match the oxide layer. This parameter change (chemical composition) resolves the etch rate difference that causes bump formation during subsequent etching processes.
Solution Approach 2:
The oxidation process creates different properties in different portions of the liner - the oxidized lining portion has etch rate similar to oxide layer, while the unoxidized lining portion maintains original properties. This local differentiation allows selective etching behavior to prevent bumps.
2Manufacturing precision
If liner is oxidized to have similar etch rate with oxide layer, then bump formation is reduced, but process complexity increases
Solution Approach 1:
The liner is oxidized in advance before the mask layer formation and subsequent etching processes. This preliminary oxidation action ensures that when etching occurs later, both the oxide layer and liner have similar etch rates, preventing bump formation without requiring additional corrective steps.
Solution Approach 2:
The oxidation process acts as an intermediary step that modifies the liner properties before the main etching process. By introducing this intermediate treatment, the system achieves uniform etching behavior between oxide and liner materials.
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 approach ensures that the oxide layer and liner have similar remaining heights after etching, minimizing the formation of bumps on the mask layer and preserving the design pattern of the memory device without the need for additional planarization processes.
Implementation Method 1
The liner is oxidized
Data Source
AI summary
A method includes a number of operations. An oxide layer is formed in an isolation trench over a substrate. A liner is formed over the oxide layer. The liner is oxidized. An implant region is formed over the substrate after the liner is oxidized. The oxide layer and the liner are etched after the implant region is formed. A word line structure is formed over the substrate and across the oxide layer and the liner.