Pointed Trench Isolation for Backside Contact Short Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The increased risk of short circuits between backside contacts of neighboring transistors due to reduced tip-to-tip spacing in semiconductor devices, particularly when transistors carry opposite charges, poses a challenge in semiconductor manufacturing.
Innovation Solution
A trench isolation structure with a pointy bottom and conformal liners is introduced to create larger contact areas and provide insulation between backside contacts, while ensuring self-alignment with source/drain regions, using materials like silicon-nitride and silicon-oxide to form backside contacts and power rails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the tip-to-tip spacing between neighboring transistors is reduced to increase device density, then the area occupied by transistors is reduced, but the risk of short circuits between backside contacts increases
Solution Approach 1:
A trench isolation structure is introduced as an intermediary element between neighboring transistors. This trench, filled with dielectric material and lined with conformal liners, acts as a physical barrier and electrical insulator that prevents short circuits between backside contacts while allowing the transistors to be placed closer together, thereby maintaining high device density without compromising reliability
2Ease of manufacture
If conventional trench isolation structures are used, then the manufacturing process is simpler, but the contact area for backside contacts is limited
Solution Approach 1:
The trench isolation structure incorporates conformal liners that are deposited to follow the contour of the trench walls. This creates a localized expansion of the contact area at the trench opening while maintaining a manageable trench depth. The contact area is enhanced locally where needed for backside contact formation, while the overall structure remains manufacturable through standard deposition and etching processes
3Reliability
If the trench isolation depth is increased to improve insulation, then the insulation between backside contacts is enhanced, but the manufacturing complexity increases
Solution Approach 1:
The conformal liners are deposited with controlled thickness parameters to achieve optimal insulation without requiring excessive trench depth. By adjusting the deposition thickness and composition of the conformal liners, sufficient electrical insulation is achieved at moderate trench depths, balancing reliability requirements with manufacturing simplicity. The liner thickness is tuned to provide adequate insulation while remaining compatible with standard fabrication capabilities
Data Source
AI summary
Embodiments of present invention provide a semiconductor structure. The semiconductor structure includes a trench isolation between a first source/drain region of a first transistor and a second source/drain region of a second transistor, wherein the trench isolation includes an upper portion and a lower portion; the lower portion has a first lower sidewall and a second lower sidewall that intersects with the first lower sidewall to form a pointy bottom of the trench isolation; a first lower conformal liner at the first lower sidewall and a second lower conformal liner at the second lower sidewall; and the first and second lower conformal liners pinch off at the pointy bottom. A method of forming the same is also provided.