Gate Isolation Structure for Metal Gate CD Control
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Solution Overview
Problem
Existing technologies face issues with critical dimension shrinkage of metal gate layers due to processing variations, leading to undesired lateral expansion of gate cut trenches, which adversely affect process windows and contact formation in semiconductor devices.
Innovation Solution
Forming dummy fins with a v-shaped top surface or two layers of different etching selectivities to limit lateral expansion of gate cut trenches, ensuring the integrity of metal gate layers by blocking undesired expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional gate isolation structures are used, then manufacturing process is simple, but critical dimension shrinkage of metal gate layers occurs due to processing variations
Solution Approach 1:
The gate isolation structure is formed in advance before the metal gate layers are deposited. This preliminary formation of the isolation structure with precise dimensions establishes a foundation that prevents subsequent lateral expansion during processing, thereby maintaining critical dimensions of the metal gate layers without requiring complex in-process adjustments
Solution Approach 2:
The gate isolation structure acts as an intermediary element between the substrate and the metal gate layers. By positioning this isolation structure with precise critical dimensions, it serves as a physical barrier that mediates and prevents unwanted lateral expansion of the metal gate layers during subsequent processing steps
2Manufacturing precision
If conventional gate isolation structures are used, then fabrication process is straightforward, but lateral expansion of gate cut trenches occurs adversely affecting process windows
Solution Approach 1:
The invention changes the critical dimension parameter of the gate isolation structure to be larger than conventional structures. This parameter change creates a buffer zone that compensates for processing variations and prevents lateral expansion of gate cut trenches, thereby maintaining adequate process windows without requiring complex fabrication adjustments
3Manufacturing precision
If conventional gate isolation structures are used, then manufacturing is simple, but contact formation is adversely affected due to lateral expansion
Solution Approach 1:
The gate isolation structure is preliminarily formed with extended dimensions before contact formation steps. This advance preparation creates defined boundaries that prevent lateral expansion during subsequent processing, ensuring precise contact formation without requiring complex real-time adjustments during contact fabrication
Data Source
AI summary
A semiconductor device includes a first semiconductor fin and a second semiconductor fin extending along a first direction. The semiconductor device includes a dielectric fin, extending along the first direction, that is disposed between the first and second semiconductor fins. The semiconductor device includes a gate isolation structure vertically disposed above the dielectric fin. The semiconductor device includes a metal gate layer extending along a second direction perpendicular to the first direction, wherein the metal gate layer includes a first portion straddling the first semiconductor fin and a second portion straddling the second semiconductor fin. The gate isolation structure has a central portion and one or more side portions, the central portion extends toward the dielectric fin a further distance than at least one of the one or more side portions.