Grating Trench Contact Link for Dense Nanowire Gate Cuts
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Solution Overview
Problem
The challenge of maintaining mobility improvement and short channel control in multi-gate transistors as device dimensions scale below the 10 nanometer node is compounded by the constraints on lithographic processes used to pattern features, leading to issues with critical dimension and spacing in semiconductor fabrication.
Innovation Solution
The implementation of integrated circuit structures with grating trench contacts and trench contact links, which involve a metal gate cut process after completing gate dielectric and work function metal deposition, allowing for seamless work function metal deposition and reducing process cost and variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional lithographic processes are used to pattern features at smaller dimensions, then device density increases, but the spacing between features and critical dimension control deteriorate
Solution Approach 1:
The trench contact structure is segmented into multiple portions (first trench contact portion, second trench contact portion, and trench contact link) that are formed separately and then connected. This segmentation allows each portion to be optimized independently for lithographic patterning while maintaining overall electrical connectivity, resolving the conflict between high device density and precise dimensional control.
Solution Approach 2:
The trench contact link serves as an intermediary element that electrically connects the first and second trench contact portions. This intermediary structure enables the separation of contact formation into distinct lithographic steps, allowing relaxed spacing requirements for individual features while achieving the desired overall contact function and maintaining manufacturing precision.
2Reliability
If gate cut plugs are removed to reestablish trench contact continuity, then electrical connection is restored, but process complexity and cost increase
Solution Approach 1:
The trench contact link is formed in advance during the initial trench contact formation process, positioned to bridge potential gate cut plug locations. This preliminary action ensures that even if gate cut plugs are present, the trench contact continuity is pre-established through the link structure, eliminating the need for subsequent complex plug removal operations and reducing process complexity.
Solution Approach 2:
The trench contact link creates a redundant electrical pathway that copies the intended contact continuity function. Instead of relying on a single continuous contact that must be precisely maintained through complex processes, the link provides an alternative routing that achieves the same electrical continuity goal with simpler manufacturing steps.
3Productivity
If trench contact spacing is reduced to increase device density, then more devices fit on chip, but metal fill becomes constrained
Solution Approach 1:
The trench contact is divided into separate portions with the link connecting them, allowing the metal fill to be deposited in a segmented manner. This segmentation enables metal to be filled into each portion and the link independently, effectively utilizing the available space even at reduced spacing, thereby maintaining adequate metal fill capability while achieving high device density.
Data Source
AI summary
Integrated circuit structures having grating trench contact with trench contact links are described. For example, an integrated circuit structure includes a vertical stack of horizontal nanowires or a fin. A gate electrode is over the vertical stack of horizontal nanowires of the fin. A conductive trench contact is adjacent to the gate electrode. A dielectric sidewall spacer is between the gate electrode and the conductive trench contact. A gate cut plug extends through the gate electrode and the dielectric sidewall spacer, the gate cut plug extending into but not entirely through the conductive trench contact. A trench contact plug is adjacent to the gate cut plug, the trench contact plug extending through a remainder of the conductive trench contact. A conductive trench contact link is in a recess in the gate cut plug and the trench contact plug, the conductive trench contact.