Memory Cell Layout With Dummy Word Lines and STI Segmentation
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Solution Overview
Problem
The miniaturization of semiconductor devices poses challenges in maintaining performance due to the shrinking size of active areas and the complexity of integrated circuits, leading to limitations in the fabricating process.
Innovation Solution
A semiconductor memory device design that incorporates dummy word lines on the outer side to protect inner word lines, along with an active structure featuring first and second active fragments with varying lengths, and shallow trench isolations to enhance device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the width of active areas is reduced to meet miniaturization requirements, then device size is reduced, but manufacturing precision becomes more difficult to maintain
Solution Approach 1:
The active structure is divided into multiple active fragments separated by shallow trench isolations. This segmentation allows each fragment to be independently formed with standard precision, while the overall device achieves miniaturization through the compact arrangement of multiple smaller units rather than relying on a single large active area with high precision requirements.
2Productivity
If the pitch between active areas is reduced to increase integration density, then device functionality is enhanced, but manufacturing precision deteriorates
Solution Approach 1:
The active structure is divided into multiple active fragments separated by shallow trench isolations. This segmentation allows each fragment to be independently formed with standard precision, while the overall device achieves miniaturization through the compact arrangement of multiple smaller units rather than relying on a single large active area with high precision requirements.
Solution Approach 2:
Shallow trench isolations are introduced as intermediary structures between active fragments. These isolations serve as spacers that define the pitch between active areas, transferring the precision requirement from direct active area spacing to the isolation structure formation, which can be accomplished with less stringent precision requirements.
3Device complexity
If inner word lines are directly connected to bit lines through active structure, then device complexity is reduced, but device performance deteriorates due to interference
Solution Approach 1:
Dummy word lines are introduced as intermediary structures between the inner word lines and the active structure/bit lines. These dummy word lines act as isolation barriers that prevent direct connection and interference, while maintaining a relatively simple overall connection structure. The dummy word lines can be formed using the same process as regular word lines, adding minimal complexity to the fabrication process.
Data Source
AI summary
A semiconductor memory device includes a substrate, an active structure, a shallow trench isolation and a plurality of word lines. The active structure is disposed in the substrate, and includes a plurality of first active fragments and a plurality of second active fragments extended parallel to each other along a first direction and the second active fragments are disposed outside a periphery of all of the first active fragments. The shallow trench isolation is disposed in the substrate to surround the active structure, and which includes a plurality of first portions and a plurality of second portions. The word lines are disposed in the substrate, parallel with each other to extend along a second direction, wherein at least one of the word lines are only intersected with the second active fragments, or at least one of the word lines does not pass through any one of the second portions.