Dummy Gate Structure for FinFET Integration and Contact Accuracy
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Solution Overview
Problem
Conventional FinFET fabrication faces issues with inaccurate contact hole formation, leading to 'tiger tooth' defects and poor integration of metal gates and contact plugs, affecting device performance.
Innovation Solution
The semiconductor device and method involve forming a fin structure with a trench, a liner, and a dummy gate structure where the bottom surface of the dummy gate and the top surface of the fin are on the same level, allowing the dummy gate to stretch over adjacent fin structures and trenches, and using spacer layers to control the trench dimension, thereby enhancing integration and avoiding overreaction or over-consumption during shallow trench isolation processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact holes are formed with poor accuracy in conventional FinFET fabrication, then manufacturing complexity is reduced, but device reliability deteriorates due to tiger tooth defects and poor interconnection
Solution Approach 1:
The dummy gate structure is formed in advance before contact hole formation. This preliminary structure serves as a protective mask and reference feature that guides subsequent processing steps, ensuring accurate contact hole placement and preventing tiger tooth defects. The dummy gate is positioned to extend over the trench and adjacent fin structures, providing a buffer zone that maintains dimensional accuracy during later etching and deposition processes.
Solution Approach 2:
The dummy gate structure acts as an intermediary element between the fin structures and the contact holes. By extending over the trench and adjacent fins, it serves as a protective intermediary that prevents direct exposure of critical structures to harsh processing conditions, thereby maintaining manufacturing precision while improving reliability.
2Manufacturing precision
If the trench critical dimension is enlarged due to overreaction with oxygen during shallow trench isolation or dielectric layer formation, then process simplicity is maintained, but manufacturing precision deteriorates
Solution Approach 1:
The dummy gate structure is designed to extend over the trench and adjacent fin structures before the shallow trench isolation or dielectric layer formation. This preliminary positioning creates a protective barrier that prevents oxygen from reaching and reacting with the trench edges during subsequent processing. The dummy gate effectively counteracts the potential expansion effect before it can occur, maintaining the original critical dimension without requiring additional process controls.
3Adaptability or versatility
If a dummy gate structure stretches over etched edges of two adjacent fin structures and the trench, then integration is improved, but device complexity increases
Solution Approach 1:
The dummy gate structure performs multiple functions simultaneously: it serves as a protective mask for the trench and adjacent fins, provides a reference feature for alignment, acts as a barrier to prevent oxygen exposure, and maintains structural integrity during processing. By consolidating these multiple functions into a single structure, the patent achieves high integration without proportionally increasing complexity.
Data Source
AI summary
The present invention further provides a method for forming a semiconductor device, comprising: first, a substrate having a fin structure disposed thereon is provided, wherein the fin structure has a trench, next, a first liner in the trench is formed, a first insulating layer is formed on the first liner, afterwards, a shallow trench isolation is formed in the substrate and surrounding the fin structure, wherein a bottom surface of the shallow trench isolation is higher than a bottom surface of the first insulating layer, and a top surface of the shallow trench isolation is lower than a top surface of the first insulating layer, and a dummy gate structure is formed on the first insulating layer and disposed above the trench, wherein a bottom surface of the dummy gate structure and a top surface of the fin structure are on a same level.