Nitride Liner Barrier for Memory Device Oxygen Diffusion Control
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Solution Overview
Problem
The manufacturing process of memory devices often results in poor electrical performance due to oxygen diffusion causing Bird's Beak and uneven nitrogen distribution in the isolation structure, leading to unstable gate coupling ratios and increased critical voltage distribution.
Innovation Solution
A manufacturing method involving a liner material layer with a first oxide liner, a nitride liner, and a second oxide liner is used, where the nitride liner is positioned to prevent oxygen diffusion and the second oxide liner is formed through low-temperature plasma oxidation to stabilize the nitride liner, ensuring an even surface and preventing nitrogen diffusion into the isolation material layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oxidation process is performed on the isolation material layer to achieve good isolation effects, then the isolation structure has a higher proportion of oxygen atoms and achieves good isolation effects, but oxygen diffuses to the tunneling dielectric layer causing Bird's Beak and poor electrical performance
Solution Approach 1:
A nitride liner layer is introduced as an intermediary barrier between the oxidation-prone isolation material layer and the oxygen-sensitive tunneling dielectric layer. This nitride layer prevents oxygen diffusion during the oxidation process, thereby eliminating Bird's Beak while maintaining effective isolation.
2Object-affected harmful factors
If the nitride liner layer is used to prevent oxygen diffusion, then Bird's Beak is prevented, but nitrogen diffusion into the isolation material layer during annealing causes uneven etching rate and unstable gate coupling ratio
Solution Approach 1:
An oxide protection layer serves as a temporary intermediary barrier during the annealing process. This protective layer prevents nitrogen from the nitride liner layer from diffusing into the isolation material layer, thereby maintaining uniform etching characteristics while preserving the oxygen-blocking function of the nitride layer.
3Object-affected harmful factors
If a simple nitride liner layer is used to prevent oxygen diffusion, then Bird's Beak is prevented, but the structure is insufficient to prevent nitrogen diffusion during annealing
Solution Approach 1:
The liner structure is designed as a composite of multiple layers: a nitride liner layer for oxygen diffusion prevention, an oxide protection layer for nitrogen diffusion prevention during annealing, and an optional second nitride layer for enhanced protection. This composite structure addresses both diffusion issues while maintaining manufacturing feasibility.
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 prevents Bird's Beak and nitrogen diffusion, resulting in a stable gate coupling ratio and reduced critical voltage distribution, thereby enhancing the electrical performance of memory devices.
Implementation Method 1
a first oxide liner material layer covering the stack structures is formed on the substrate
Implementation Method 2
a nitride liner layer and the second oxide liner material layer are disposed on the first oxide liner material layer
Implementation Method 3
the second oxide liner is formed through low-temperature plasma oxidation to stabilize the nitride liner
Implementation Method 4
The oxidation process enables the resultant isolation structure to have a higher proportion of oxygen atoms and achieve good isolation effects
Data Source
AI summary
A memory device and a manufacturing method of the memory device are provided. The manufacturing method includes steps below. A plurality of stack structures including a tunneling dielectric layer and a floating gate are formed on a substrate. A liner material layer including a nitride liner layer is formed on the substrate. A top surface of the nitride liner layer is lower than a top surface of the floating gate and is higher than a top surface of the tunneling dielectric layer. An isolation material layer covering the liner material layer is formed on the substrate. The isolation material layer is oxidized, and a portion of the isolation material layer is removed to form an isolation structure. An inter-gate dielectric layer covering the stack structures and the isolation structure is formed on the substrate. A control gate covering the inter-gate dielectric layer is formed on the substrate.