Gate Cut Plug Removal From Trench Contacts Using Angled Etch
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Solution Overview
Problem
The scaling of multi-gate and nanowire transistors in integrated circuits poses challenges due to constraints on lithographic processes, particularly in maintaining critical dimension and spacing, leading to trade-offs in feature pattern dimensions and device performance.
Innovation Solution
The implementation of a directional etch tool using an angled plasma beam to remove metal gate cut plugs from trench contacts, allowing for self-aligned and cost-effective plug removal without the need for additional lithography masks, thereby improving process robustness and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithographic processes are used to pattern transistor features, then critical dimension control is achieved, but spacing between features becomes constrained
Solution Approach 1:
The patent introduces a lateral offset between the gate cut plug and the trench contact by using an angled directional etch (e.g., 45-degree angle). This dimensional approach allows the plug to be positioned relative to the contact without requiring additional lithographic spacing, effectively adding a spatial dimension to resolve the critical dimension versus spacing trade-off.
2Manufacturing precision
If gate cut plugs are removed using additional lithography masks, then plug removal precision is improved, but process complexity and cost increase
Solution Approach 1:
The angled directional etch process is self-aligned to the trench contact structure, eliminating the need for separate lithography masks. The etch automatically positions the gate cut plug removal at the correct location relative to the contact, making the process self-service and reducing overall process complexity.
Solution Approach 2:
The angled etch creates a lateral offset between the gate cut plug and trench contact during the plug formation process itself, preparing the structure in advance for seamless metal fill. This preliminary positioning action eliminates the need for subsequent mask-based removal operations.
3Reliability
If gate cut plugs extend into trench contacts, then contact isolation is improved, but metal fill voids increase
Solution Approach 1:
By using an angled directional etch, the gate cut plug is laterally offset from the trench contact position. This dimensional shift ensures that the plug does not extend vertically into the contact region, eliminating the source of metal fill voids while preserving the isolation function through the angled geometry.
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 enables seamless work function metal deposition, reduces voids during metal fill, and enhances the robustness of the integrated circuit structure by maintaining continuity in the trench contact, thus improving device performance and reducing manufacturing costs.
Implementation Method 1
directional etch tool using an angled plasma beam to remove metal gate cut plugs from trench contacts
Data Source
AI summary
Integrated circuit structures having gate cut plugs removed from trench contacts, and methods of fabricating integrated circuit structures having gate cut plugs removed from trench contacts, are described. For example, an integrated circuit structure includes a vertical stack of horizontal nanowires. A gate electrode is over the vertical stack of horizontal nanowires. 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 extends to and is conformal with a side of the conductive trench contact.