Semiconductor Memory Cell Layout With Dummy Bit-Lines and Landing Pads
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Solution Overview
Problem
The increasing integration level of semiconductor memory devices complicates the process of forming wire lines and buried contacts, leading to reliability and performance challenges.
Innovation Solution
A semiconductor memory device design with a cell area and peripheral area, featuring dummy and normal bit-lines, where the dummy bit-lines have a specific width ratio and spacing relative to normal bit-lines, along with the use of landing pads to enhance contact areas, improving manufacturing reliability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the integration level of semiconductor memory devices is increased, then more semiconductor elements can be implemented in the same area, but the process of forming wire lines and buried contacts becomes increasingly complex and difficult
Solution Approach 1:
The cell area is divided into a normal cell area and a dummy cell area, with the dummy cell area containing dummy bit-lines that are segmented and arranged in a specific pattern. This segmentation helps simplify the formation process of wire lines and buried contacts by providing a structured approach to handling the increasing number of elements.
Solution Approach 2:
Different regions of the device are given different properties: the normal cell area contains functional bit-lines while the dummy cell area contains dummy bit-lines with specific width ratios (1:2 or 1:3 relative to normal bit-lines). This local differentiation allows the dummy structures to serve as placeholders or test structures that simplify the overall manufacturing process.
2Quantity of substance
If the integration level is increased, then circuit patterns become smaller, but manufacturing precision requirements increase
Solution Approach 1:
The dummy bit-lines are designed with specific width parameters (1:2 or 1:3 ratio compared to normal bit-lines) and specific spacing relationships. These parameter changes allow for easier manufacturing control while maintaining the required integration level, as the dummy structures can be formed with relaxed precision requirements compared to functional structures.
3Reliability
If dummy cell area width is increased to improve contact formation, then manufacturing reliability improves, but device area increases
Solution Approach 1:
The width of the dummy cell area is optimized to specific ranges (50-200 nm) based on the bit-line pitch and width ratios. These parameter optimizations ensure that the dummy cell area is large enough to improve contact formation reliability but small enough to minimize the overall device area.
Data Source
AI summary
A semiconductor memory device includes a substrate including a cell area and a peripheral area defined by a periphery of the cell area, the cell area including a dummy cell area and a normal cell area, and an active area defined by a cell element isolation film. The device includes a cell area separation film defining the cell area in the substrate, the dummy cell area defining a boundary with the cell area separation film between the normal cell area and the cell area separation film. The device includes a normal bit-line on the normal cell area and extending in a first direction, a dummy bit-line group on the dummy cell area, the dummy bit-line group including a plurality of dummy bit-lines extending in the first direction, and a plurality of storage contacts connected to the active area and located along a second direction perpendicular to the first direction.