Self-Aligned FinFET Gate Isolation for Precise Spacer Alignment
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Solution Overview
Problem
The challenge in semiconductor manufacturing is to create smaller and more complex circuits while maintaining structural integrity and reducing resistance in semiconductor devices, particularly in FinFETs, where traditional methods struggle with alignment and spacing issues during the formation of isolation structures and gate replacement processes.
Innovation Solution
A method involving self-aligned isolation fins and gate replacement is employed, utilizing double-patterning or multi-patterning processes to form fins and trenches, followed by deposition and etching techniques to create self-aligned isolation structures, which are then integrated with gate spacers and metal gate electrodes, ensuring precise alignment and reduced resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional manufacturing methods are used for FinFET isolation structures, then the manufacturing process is simpler, but alignment precision and spacing control deteriorate
Solution Approach 1:
The method performs preliminary patterning to form mandrels and isolation structures before final gate formation. The isolation fins are formed in advance using self-aligned processes, ensuring precise positioning relative to active fins before the gate structure is completed, thereby achieving high alignment precision without requiring complex real-time alignment processes.
Solution Approach 2:
The patent introduces self-aligned isolation fins as intermediary structures that mediate between the substrate and the final gate structure. These isolation fins serve as reference structures that automatically align with active fins through the self-aligned process, eliminating the need for complex photolithographic alignment while ensuring precise spacing control.
2Productivity
If geometry size is reduced to increase functional density, then production efficiency improves and costs decrease, but structural integrity and alignment precision deteriorate
Solution Approach 1:
The self-aligned isolation fin formation process is self-service in nature, where the isolation structures automatically position themselves relative to active fins through the patterning process without requiring additional alignment steps. This self-alignment mechanism maintains precision even as feature sizes scale down, enabling continued productivity improvement without sacrificing alignment quality.
Solution Approach 2:
The patent transitions from planar alignment to three-dimensional self-aligned formation by creating vertical isolation fins that extend from the substrate surface. This dimensional transition allows alignment to be determined by vertical growth and lateral etching rather than by photolithographic overlay, maintaining precision at smaller geometries while improving production efficiency.
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 enhances the structural integrity and reduces resistance in semiconductor devices by providing precise alignment and controlled spacing, enabling the formation of efficient and reliable FinFETs with improved performance.
Implementation Method 1
a first dielectric layer is deposited over the substrate and over the fins
Implementation Method 2
a second dielectric layer is deposited over the first dielectric layer
Implementation Method 3
a first trench is etched through the second dielectric layer and through the first dielectric layer to expose a top surface of the substrate
Data Source
AI summary
A semiconductor device includes an active fin disposed on a substrate, a gate structure, and a pair of gate spacers disposed on sidewalls of the gate structure, in which the gate structure and the gate spacers extend across a first portion of the active fin, and a bottom surface of the gate structure is higher than a bottom surface of the gate spacers.