MOS Gate Structure Isolation via Tapered Opening Etching
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Solution Overview
Problem
The challenge in semiconductor manufacturing is to reduce leakage current and improve the integrity and performance of semiconductor structures as critical dimensions shrink, particularly in forming effective isolation and gate structures in MOS transistors.
Innovation Solution
A method involving etching a portion of the initial device gate structure at junctions between adjacent device unit regions to form a top opening, followed by forming a spacer layer and creating a bottom opening, which adjusts the width of the openings to enhance the process window and improve isolation between device unit regions, thereby improving the integrity and performance of the semiconductor structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the initial device gate structure is etched at junctions between adjacent device unit regions to form openings, then isolation between device unit regions is improved, but the complexity of the manufacturing process increases
Solution Approach 1:
The gate structure is segmented into multiple parts by forming openings at the junctions between adjacent device unit regions. This segmentation isolates adjacent devices electrically while maintaining structural integrity through the remaining gate portions, directly resolving the isolation quality issue.
Solution Approach 2:
The method performs preliminary etching to form openings in the gate structure before final device fabrication steps. By pre-establishing the isolation structure, subsequent processing is simplified and the overall manufacturing complexity is managed more effectively.
2Ease of manufacture
If the width of the top opening is increased to improve the process window, then the ease of manufacture is improved, but the area occupied by the gate structure is reduced
Solution Approach 1:
The opening structure transitions from a single-level to a multi-level configuration with both top and bottom openings. This dimensional change allows the top opening width to be increased for better manufacturability while the bottom opening maintains the effective gate area, resolving the contradiction between ease of manufacture and gate structure area.
Solution Approach 2:
The bottom opening is nested within the region defined by the top opening, creating a hierarchical structure. This nesting allows the top opening to be wider for manufacturing ease while the bottom opening preserves the functional gate area, effectively resolving the area contradiction.
3Manufacturing precision
If a spacer layer is formed on the side wall of the top opening to adjust the bottom opening width, then the manufacturing precision is improved, but the device complexity increases
Solution Approach 1:
A spacer layer is introduced as an intermediary element on the side wall of the top opening. This spacer serves as a precise template that defines the width of the bottom opening through subsequent etching, achieving high manufacturing precision while the spacer can be removed after serving its function.
Solution Approach 2:
The spacer layer thickness is controlled to precisely adjust the bottom opening width. By changing the spacer thickness parameter, the bottom opening dimensions are accurately controlled, achieving high manufacturing precision. The temporary nature of the spacer reduces long-term structural complexity.
Data Source
AI summary
A semiconductor structure and a method for forming same are provided, the forming method including: providing a base including a plurality of adjacent device unit regions, an initial device gate structure spanning a plurality of device unit regions being formed on the base; etching a portion of the initial device gate structure in thickness at a junction between the adjacent device unit regions to form a top opening; forming a spacer layer on a side wall of the top opening; etching a remainder of the initial device gate structure exposed from the spacer layer, and forming a bottom opening exposed from the base within the remainder of the initial device gate structure, the remainder of the initial device gate structure being used as a device gate structure; and forming an isolation structure within the top opening and the bottom opening. The spacer layer is configured to adjust a width of the bottom opening, so that the width of the bottom opening is less than a width of the top opening. Therefore, the width of the top opening can be increased properly to enlarge a process window in which the top opening is formed, thereby better implementing isolation between the adjacent device unit regions and improving integrity of the device gate structure, further helping improve performance of a transistor.