Metal Gate and Trench Contact Cut Plugs for Tighter IC Cell Scaling
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Solution Overview
Problem
The challenge of maintaining mobility improvement and short channel control in microelectronic devices as device dimensions scale below the 10 nanometer node, particularly in multi-gate and nanowire transistors, is exacerbated by the constraints on lithographic processes used to pattern features, leading to a trade-off between critical dimension and spacing.
Innovation Solution
The implementation of a 'plug-last' approach in integrated circuit fabrication, where metal gate cuts and trench contact plugs are formed after gate dielectric and work function metal deposition, allowing for reduced-dimension dielectric structures and seamless metal fill, thereby alleviating space constraints and improving device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional lithographic processes are used to pattern features in multi-gate and nanowire transistors, then device dimensions can be scaled down, but the spacing between features must be increased to maintain manufacturing precision
Solution Approach 1:
The patent inverts the conventional sequence by performing metal gate cuts and trench contact plug formations after gate dielectric and work function metal deposition, rather than before. This reversal allows reduced-dimension dielectric structures to be created without compromising the spacing requirements of lithographic patterning, as the cuts are made in already-deposited materials rather than requiring additional lithography steps
Solution Approach 2:
The patent transitions from two-dimensional planar patterning constraints to three-dimensional structure manipulation by forming vertical trenches and performing cuts in the vertical dimension after deposition. This allows the critical horizontal spacing to be maintained while achieving the necessary feature separations through vertical trench formation and selective plug placement
2Device complexity
If metal gate cuts and trench contact plugs are formed before gate dielectric deposition, then the structure can be simplified, but voids and process variation increase
Solution Approach 1:
The patent performs gate dielectric and work function metal deposition before forming metal gate cuts and trench contact plugs. This preliminary action ensures that the gate dielectric layer is already in place and properly conformal before any cutting or trench formation occurs, preventing voids and ensuring clean interfaces between the dielectric and subsequent metal fills
Data Source
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AI summary
Integrated circuit structures having uniform grid metal gate and trench contact cuts plugged with reduced-dimension dielectric structures 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 or the fin. A conductive trench contact structure is adjacent to the gate electrode. A dielectric sidewall spacer is between the gate electrode and the conductive trench contact structure. A dielectric cut plug structure extends through the gate electrode, through the dielectric sidewall spacer, and through the conductive trench contact. The dielectric cut plug structure has a lateral width adjacent to the gate electrode less than a lateral width adjacent to the conductive trench contact structure.