Semiconductor Contact Structure for Precise BEOL Etching Alignment
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Solution Overview
Problem
The manufacturing of semiconductor devices with increasingly smaller critical dimensions faces challenges in the formation of conductive interconnect structures, leading to defects and poor reliability due to etching deviations in the Back End of Line process, which affects the performance and alignment accuracy of contact structures.
Innovation Solution
A semiconductor device design with a contact structure comprising a first and second contact sub-structure, where the first dimension at the boundary between them is smaller than the second, and an insulation structure is used to control etching, reducing contact resistance and preventing damage to air gaps, thereby improving alignment accuracy and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional etching processes are used for contact structure formation, then manufacturing simplicity is maintained, but alignment accuracy deteriorates due to etching deviations
Solution Approach 1:
The contact structure is divided into two sub-structures: a first contact sub-structure that contacts the conductive line and a second contact sub-structure located above it. This segmentation allows each sub-structure to be optimized independently, with the first sub-structure ensuring precise alignment through its smaller dimension and the second sub-structure providing structural support and electrical connection, thereby resolving the contradiction between alignment accuracy and manufacturing simplicity.
Solution Approach 2:
The first contact sub-structure is designed with a smaller dimension in the second direction compared to the second contact sub-structure. This local quality differentiation ensures that the critical alignment interface with the conductive line has higher precision while the upper portion maintains structural integrity and electrical conductivity, effectively addressing the alignment accuracy issue without requiring complete redesign of the entire contact structure.
2Manufacturing precision
If contact structure dimensions are reduced to maintain density, then component density is improved, but manufacturing precision deteriorates due to etching deviations
Solution Approach 1:
The contact structure utilizes vertical stacking in the third direction to achieve high component density while maintaining controllable horizontal dimensions. By transitioning from a single-planar contact to a three-dimensional stacked structure, the design allows smaller footprints in the first and second directions (improving density) while the vertical dimension provides additional degrees of freedom for precise alignment and etching control.
Solution Approach 2:
Dividing the contact structure into two sub-structures enables independent optimization of dimensions for each part. The first contact sub-structure can be precisely controlled in size for accurate alignment with the conductive line, while the second contact sub-structure can be designed with appropriate dimensions for structural support, thereby maintaining manufacturing precision even as overall device density increases.
3Manufacturing precision
If insulation structure is added to control etching, then etching control is improved, but device complexity increases
Solution Approach 1:
The insulation structure acts as an intermediary element between the etching process and the conductive line. It provides a controlled interface that allows precise etching depth control while protecting the conductive line from damage. This intermediary structure simplifies the etching process by providing a clear stopping point and reduces the need for complex multi-step etching procedures, thereby improving etching control without proportionally increasing device complexity.
Solution Approach 2:
The insulation structure is formed in advance before the contact structure etching process. This preliminary action establishes a predefined etching stop layer that guides subsequent etching operations, ensuring precise depth control and preventing over-etching. By preparing this protective and guiding structure beforehand, the actual contact formation process becomes simpler and more controlled.
Data Source
AI summary
The present disclosure provides semiconductor devices, formation methods thereof, and memory systems. The semiconductor device includes: conductive lines extending along a first direction and spaced apart along a second direction, wherein the first direction intersects the second direction; and a contact structure extending along a third direction and at least connected to a first conductive line of the conductive lines, wherein the contact structure includes a first contact sub-structure connected with the first conductive line and a second contact sub-structure on the first contact sub-structure; in the second direction, a first dimension of the first contact sub-structure at a boundary between the first contact sub-structure and second contact sub-structure is smaller than a second dimension of the second contact sub-structure at the boundary between the first contact sub-structure and second contact sub-structure, wherein the third direction is perpendicular to both the first direction and second direction.