Buried Bit Line Trench Segmentation for Uniform Sidewall Contacts
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Solution Overview
Problem
Conventional semiconductor device fabrication processes face challenges in achieving uniformity of side contacts and junctions due to difficulties in aligning masks and uniformly exposing sidewalls, leading to degraded electrical characteristics.
Innovation Solution
The semiconductor device employs active regions separated by alternating trenches with different widths, featuring separation layers and buried bit lines interposed between them, along with junctions and side contacts formed on the sidewalls, to ensure uniformity and stability of electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an etching process is used to expose the sidewall of active regions to form junctions and side contacts, then the sidewall can be accessed for forming electrical connections, but it becomes difficult to align masks and uniformly expose the sidewall portion
Solution Approach 1:
The trench is divided into multiple sections by introducing separation layers at specific positions. This segmentation allows different portions of the trench to be processed independently, enabling uniform exposure of sidewalls at designated locations while maintaining overall structural integrity. The separation layers create distinct zones where junctions and side contacts can be formed with controlled precision.
Solution Approach 2:
Separation layers are formed in advance within the trench structure before the etching process that exposes the sidewalls. This preliminary action pre-defines the regions where sidewall exposure will occur, ensuring that subsequent mask alignment and etching processes can proceed with improved precision and uniformity, as the target areas are already predetermined by the separation layers.
2Reliability
If side contacts are formed on the sidewall of active regions to connect buried bit lines and junctions, then electrical connections can be established, but processing difficulties increase and uniform characteristics are hard to secure
Solution Approach 1:
By dividing the trench into multiple sections using separation layers, the formation of side contacts and junctions is segmented into discrete, manageable steps. Each section can be processed independently with standardized procedures, reducing overall processing complexity while ensuring uniform electrical characteristics across all contacts and junctions.
Solution Approach 2:
Separation layers act as intermediary structures that facilitate the formation of side contacts and junctions. These layers provide a controlled interface between the buried bit lines and active regions, simplifying the processing steps required to achieve reliable electrical connections while maintaining uniformity across the device.
3Device complexity
If conventional trench structures are used for buried bit lines, then the structure is simple, but it is difficult to ensure uniformity of side contacts and junctions
Solution Approach 1:
The simple trench structure is enhanced by introducing separation layers that segment the trench into multiple sections. This maintains the overall structural simplicity of the trench while adding the necessary complexity in controlled locations to ensure uniform formation of side contacts and junctions. The segmentation approach preserves ease of fabrication while improving manufacturing precision.
Solution Approach 2:
The trench structure maintains uniform properties in most regions, but local variations are introduced at specific positions where separation layers are placed. This local quality enhancement allows for precise control of sidewall exposure and uniform formation of side contacts and junctions only where needed, without complicating the entire trench structure.
Data Source
AI summary
A semiconductor device includes active regions separated by a trench, a separation layer dividing the trench, and buried bit lines buried in the trench with the separation layer interposed between the buried bit lines.