Semiconductor Memory Device Dielectric Feature Mitigates Overlay Shifts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The electrical performance of semiconductor memory devices with fork-sheet structures is adversely affected by fabrication process variations, such as overlay shifts in photolithography, which can damage dielectric walls between adjacent memory structures, impacting capacitance and overall device performance.
Innovation Solution
A method for manufacturing semiconductor memory devices involves forming fin-shaped structures, dielectric walls, and isolation walls, followed by a specific etching process to create a dielectric feature between these structures, which helps mitigate the adverse effects of process variations and maintains electrical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a forksheet structure is used to reduce spacing between transistors, then electrical performance is improved, but the device becomes more sensitive to fabrication process variations
Solution Approach 1:
The patent forms dielectric walls and isolation walls before patterning the gate electrode, establishing a protective structure in advance that prevents damage from subsequent photolithography overlay shifts. This preliminary structural preparation ensures that even if alignment varies during later processing steps, the critical dielectric features remain intact and the electrical performance is maintained.
2Manufacturing precision
If photolithography overlay precision is increased to reduce process variations, then manufacturing complexity increases
Solution Approach 1:
The patent performs the dielectric wall and isolation wall formation before the gate electrode patterning step, establishing a robust structural framework in advance. This sequencing allows subsequent photolithography steps to proceed with standard precision requirements, as the critical alignment-sensitive features have already been established with tolerance to overlay variations.
Data Source
AI summary
A semiconductor memory device includes a first dielectric wall, a second dielectric wall, first channel portions, second channel portions, an isolation wall, and a dielectric feature. The second dielectric wall is spaced apart from the first dielectric wall in a first direction. The first channel portions are disposed on a side of the first dielectric wall and are spaced apart from each other in a second direction transverse to the first direction. The second channel portions are disposed on a side of the second dielectric wall and are spaced apart from each other in the second direction. The isolation wall is located between the first dielectric wall and the second dielectric wall. The dielectric feature is disposed to separate the first dielectric wall and the isolation wall, and is disposed on the other side of the first dielectric wall opposite to the first channel portions in the first direction.