Planarization Process Using Dummy Material for Flash Memory Dishing
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Solution Overview
Problem
Current planarization processes in flash memory devices face challenges in achieving a flat top surface due to dishing issues in dielectric layers, which affect the performance and reliability of memory units.
Innovation Solution
A planarization process involving the sequential formation of first and second dielectric layers with inherent dishing, followed by the use of a dummy material to fill these dishing areas, exposing and removing specific layers to create a flat top surface, utilizing the second dielectric layer as an etch stop, and finally removing the top layers to achieve a lower flat surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dielectric layers are formed conformally to cover the pattern and substrate, then the coverage and uniformity are improved, but dishing occurs in the isolation area causing surface non-planarity
Solution Approach 1:
A dummy material is formed in advance to fill the dishing depression in the isolation area before subsequent processing steps. This preliminary action compensates for the non-planar shape caused by conformal dielectric layer formation, enabling both good conformal coverage and surface planarity to be achieved.
2Shape
If multiple dielectric layers are formed to achieve planarization, then the surface flatness is improved, but the process complexity increases
Solution Approach 1:
The dummy material serves as an intermediary element that simplifies the overall planarization process. By introducing this temporary filling material, the need for complex multi-step planarization processes is reduced, as the dummy material can be removed later after serving its planarization function.
3Shape
If dummy material is used to fill dishing, then surface planarity is improved, but additional process steps are required
Solution Approach 1:
The dummy material is formed as a preliminary step to address dishing, and its removal is integrated into subsequent existing process steps. This approach minimizes the impact on overall productivity by combining the dummy material removal with other necessary processing operations rather than adding completely separate steps.
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 process effectively addresses the dishing issue by forming a flat top surface, enhancing the planarization and reliability of memory units, thereby improving the performance and efficiency of flash memory devices.
Implementation Method 1
A first dielectric layer and a second dielectric layer are sequentially formed to conformally cover the pattern and the substrate
Implementation Method 2
A second removing process is performed to remove the exposed part of the first dielectric layer by using the second dielectric layer in the isolation area as an etch stop layer
Data Source
AI summary
A planarization process includes the following steps. A first dielectric layer and a second dielectric layer are sequentially formed to conformally cover a pattern in a cell area and a substrate in the cell area and an isolation area, thereby the first dielectric layer and the second dielectric layer having a dishing in the isolation area. A dummy material is formed in the dishing and exposes a part of the second dielectric layer right above the pattern. A first removing process is performed to remove the exposed part of the second dielectric layer. The dummy material is removed. A second removing process is performed to remove an exposed part of the first dielectric layer by using the second dielectric layer as an etch stop layer. A third removing process is performed to remove the second dielectric layer and the first dielectric layer.