Bit Line Contact Spacer Structure for Short-Circuit Prevention
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Solution Overview
Problem
As the degree of integration of semiconductor devices increases, the area occupied by patterns decreases, leading to potential short circuit defects due to conductive material remaining during contact plug formation, which existing methods fail to adequately prevent.
Innovation Solution
A semiconductor device and method involving the formation of a first spacer and a second spacer to prevent short circuits, where the second spacer is positioned between the contact plug and the first spacer, and a sacrificial spacer is used to enhance etching and gap formation, reducing the risk of dopant flow and improving etching rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the area occupied by patterns is decreased to increase degree of integration, then productivity and device density are improved, but short circuit defects occur due to conductive material remaining during contact plug formation
Solution Approach 1:
A spacer is formed around the contact plug before the conductive material filling process. This preliminary spacer structure prevents conductive material from shorting adjacent contact plugs during the filling process, thereby maintaining high integration while preventing short circuit defects
Solution Approach 2:
The spacer acts as an intermediary barrier between adjacent contact plugs. It physically separates the conductive materials during formation, preventing direct contact and short circuits while allowing the high-density layout to be maintained
2Reliability
If a spacer is formed to prevent short circuit defects, then reliability is improved, but device complexity increases due to additional fabrication steps
Solution Approach 1:
The spacer formation process is merged with the existing contact plug fabrication sequence. The spacer is formed as part of the interlayer dielectric structure, combining multiple functions into a single integrated process step rather than adding separate dedicated steps
3Manufacturing precision
If etching is performed to form contact holes and gaps, then manufacturing precision is improved, but dopant flow occurs causing contamination
Solution Approach 1:
The spacer structure is formed beforehand to create a physical barrier that prevents dopant flow during etching operations. This preliminary protective structure counteracts the harmful dopant migration before it can occur, while still allowing precise contact hole formation
Data Source
AI summary
A method for fabricating a semiconductor device includes forming a bit line contact hole in a substrate; forming a first spacer on a sidewall of the bit line contact hole; forming a sacrificial spacer over the first spacer; forming a first conductive material that fills the bit line contact hole over the sacrificial spacer; forming a second conductive material over the first conductive material; forming a bit line by etching the second conductive material; and forming a bit line contact plug and a gap between the bit line contact plug and the first spacer by partially etching the first conductive material and the sacrificial spacer to be aligned with the bit line.