Dummy Fin Separation Structure for Uniform Source/Drain Isolation
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Solution Overview
Problem
Conventional dummy fins in semiconductor devices can lead to uneven heights and merging of source/drain features due to varying fin spacings, resulting in device failures and performance issues as standard cell dimensions shrink.
Innovation Solution
A method for forming dummy fins of varying widths and structures, where first and second dummy fins etch differently to ensure even heights, using a process that includes forming fin-shaped structures with different spacings, depositing dielectric layers, and selectively etching back to achieve appropriate recesses for effective source/drain separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional dummy fins are used with varying fin spacings, then standard cell dimensions can be reduced, but uneven heights and merging of source/drain features occur causing device failures
Solution Approach 1:
The patent applies local quality by forming different dummy fin structures at different locations. Specifically, first dummy fins are formed with a first structure and second dummy fins are formed with a second structure that is different from the first structure. This allows each dummy fin to be locally optimized for its specific position and spacing requirements, preventing height uniformity issues while enabling standard cell dimension reduction.
Solution Approach 2:
The patent segments the dummy fin formation process into multiple distinct steps. First dummy fins are formed through a first etch process, then second dummy fins are formed through a second etch process. This segmentation allows independent control and optimization of each dummy fin type, resolving the contradiction between reducing standard cell dimensions and maintaining height uniformity.
2Reliability
If dummy fins are used to isolate source/drain features, then device separation is achieved, but source/drain features still merge due to uneven dummy fin heights
Solution Approach 1:
The patent implements local quality by creating different dummy fin structures tailored to specific isolation requirements. First dummy fins have a first structure optimized for their isolation function, while second dummy fins have a second structure optimized for their different isolation needs. This ensures reliable source/drain separation while maintaining precise height control for each dummy fin type.
Solution Approach 2:
The patent applies preliminary action by forming the different dummy fin structures before the source/drain feature formation process. The first and second dummy fins are created in advance with their respective structures, ensuring that when source/drain features are subsequently formed, the dummy fins are already in their final, optimized configurations for preventing feature merging.
3Ease of manufacture
If uniform dummy fin structures are used, then manufacturing process is simple, but varying fin spacings cause uneven heights and device failures
Solution Approach 1:
The patent resolves this contradiction by implementing local quality - while the overall process remains systematic and manufacturable, different dummy fin structures are created at different locations based on specific spacing requirements. First dummy fins use a first structure and second dummy fins use a second structure, maintaining ease of manufacture through a structured approach while ensuring device reliability through location-specific optimization.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures even heights of dummy fins, preventing source/drain feature merging and enabling reduction of standard cell sizes or performance improvement by maintaining separation between neighboring devices.
Implementation Method 1
a first dielectric layer is conformally deposited over the fin-shaped structures and the isolation feature
Implementation Method 2
the workpiece is planarized to form a first dummy fin between the first fin-shaped structure and the second fin-shaped structure and a second dummy fin between the second fin-shaped structure and the third fin-shaped structure
Implementation Method 3
the first dummy fin and the second dummy fin are etched back
Data Source
AI summary
A semiconductor device according to the present disclosure includes a first source/drain feature, a second source/drain feature, a third source/drain feature, a first dummy fin disposed between the first source/drain feature and the second source/drain feature along a direction to isolate the first source/drain feature from the second source/drain feature, and a second dummy fin disposed between the second source/drain feature and the third source/drain feature along the direction to isolate the second source/drain feature from the third source/drain feature. The first dummy fin includes an outer dielectric layer, an inner dielectric layer over the outer dielectric layer, and a first capping layer disposed over the outer dielectric layer and the inner dielectric layer. The second dummy fin includes a base portion and a second capping layer disposed over the base portion.