Semiconductor Memory Device Bit Line Structure
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Solution Overview
Problem
The increasing complexity of forming wiring lines and buried contacts in highly scaled semiconductor devices poses challenges in achieving reliable and efficient semiconductor memory device performance due to intricate design requirements and potential etching issues that affect the stability of electrical connections.
Innovation Solution
The semiconductor memory device incorporates a substrate with a cell region and peripheral region, utilizing a cell region isolation layer and an isolation active region to improve the design, along with specific arrangements of bit lines, gate electrodes, and conductive lines, which include sub-region isolation layers and conductive plugs to enhance electrical connections and reduce contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If highly scaled semiconductor devices are implemented with increased integration, then device density and functionality are improved, but the complexity of forming wiring lines and buried contacts increases significantly
Solution Approach 1:
The device is divided into distinct cell regions and peripheral regions, with cell regions containing memory cells and peripheral regions containing control circuits. This segmentation allows independent optimization of each region, simplifying the overall design and manufacturing process while maintaining high integration density.
Solution Approach 2:
The patent introduces a third dimension by forming bit lines that extend vertically through multiple layers, crossing over word lines in the horizontal plane. This vertical arrangement reduces the number of wiring layers needed and simplifies the formation of contacts, directly addressing the complexity issue in highly scaled devices.
2Productivity
If design rules are reduced to increase integration, then more devices fit in the same area, but manufacturing precision and etching stability deteriorate
Solution Approach 1:
Different regions of the device are assigned different functions and structures optimized for their specific purposes. Cell regions use a simplified transistor configuration with vertically extending bit lines, while peripheral regions contain control circuits with different wiring arrangements. This local optimization maintains manufacturing precision despite reduced overall design rules.
Solution Approach 2:
The device employs composite structures combining different materials and configurations - such as vertically stacked conductive layers for bit lines, isolated active regions with specific doping profiles, and multi-layer insulation structures. These composite structures enhance etching stability and connection reliability by creating well-defined interfaces and reducing process variability.
3Area of stationary object
If wiring lines and buried contacts are made finer for high integration, then device area is reduced, but electrical connection stability and reliability worsen
Solution Approach 1:
The device structure employs nested arrangements where bit lines are formed within trenches that extend through multiple layers, with word lines crossing over them. Active regions are nested within isolated regions, which are in turn nested within the larger device structure. This nesting creates well-defined, protected electrical connections that maintain stability despite reduced dimensions.
Solution Approach 2:
The patent introduces intermediary structures such as isolation regions between active regions, insulating layers between conductive lines, and contact plugs as intermediaries between different wiring layers. These intermediary elements protect electrical connections from degradation and maintain reliability even when the overall device size is reduced.
Data Source
AI summary
There is provided a semiconductor memory device capable of improving performance and reliability of an element. The semiconductor memory device includes a substrate including a cell region and a peripheral region, a cell region isolation layer in the substrate, isolating the cell region from the peripheral region, an isolation active region surrounded by the cell region isolation layer, a bit line structure on the cell region, including a cell conductive line and a cell gate electrode in the substrate of the cell region, crossing the cell conductive line.