Dummy Metal Gate Resistor Layout for Tunable IC Resistance
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Solution Overview
Problem
The fabrication of TiN resistors in semiconductor integrated circuits requires additional processes, increasing complexity and cost, and existing approaches lack flexibility in tuning resistance values and susceptibility to electro-migration.
Innovation Solution
Integrating dummy metal gates as resistors within the same gate replacement process, allowing for simultaneous formation with functional metal gates, reducing process steps and enabling flexible resistance tuning through layout design, and connecting these dummy gates in series or parallel to form resistor circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If TiN resistors are fabricated using additional processes, then resistance values can be achieved, but fabrication complexity and cost increase
Solution Approach 1:
The patent merges the formation of dummy metal gates with the formation of functional metal gates by integrating both into the same gate replacement process. This eliminates the need for separate fabrication processes for TiN resistors, thereby reducing fabrication complexity and cost while achieving the desired resistance values through the dummy gate structures
Solution Approach 2:
The gate replacement process is made universal by enabling it to form both functional metal gates for transistors and dummy metal gates for resistors simultaneously. This multi-functional approach allows the same process steps to serve dual purposes: creating active device gates and passive resistor elements, thus simplifying the overall fabrication workflow
2Manufacturing precision
If TiN resistors are fabricated using additional processes, then resistance values can be achieved, but fabrication cost increases
Solution Approach 1:
The patent combines the fabrication of dummy metal gates with functional metal gates in a single gate replacement process, eliminating the need for additional dedicated processes for TiN resistor fabrication. This merging of operations reduces material consumption, process steps, and associated costs while maintaining the ability to achieve precise resistance values through layout design
Solution Approach 2:
The dummy metal gates serve themselves as resistors without requiring separate fabrication processes. By utilizing the inherent resistance properties of the metal gate material and structure, and configuring them as dummy gates during the normal gate replacement process, the system achieves resistor functionality as a byproduct of the main fabrication process, thereby reducing costs
3Manufacturing precision
If traditional resistor approaches are used, then resistance values can be achieved, but flexibility in tuning resistance values is limited
Solution Approach 1:
The patent introduces dynamic flexibility in resistance tuning by allowing the resistance values to be adjusted through layout design parameters such as the dimensions, spacing, and configuration of the dummy metal gates. This enables continuous tuning of resistance values without requiring changes to the fabrication process itself, providing adaptability across different circuit design requirements
4Manufacturing precision
If traditional resistor approaches are used, then resistance values can be achieved, but susceptibility to electro-migration increases
Solution Approach 1:
The patent changes the physical parameters of the resistor structure by using thick metal gate layers with specific material compositions and geometries. These parameter changes include controlling the metal layer thickness, width, and length of the dummy gates, which collectively increase the resistance to electro-migration while maintaining the desired electrical resistance values for the circuits
Data Source
AI summary
An IC structure includes a resistor circuit and a transistor. The resistor circuit includes a first metal resistor strip over a semiconductor substrate, and a first metal line and a second metal line extending on a same level height above the first metal resistor strip. The first metal resistor strip is a dummy gate. Both the first metal line and the second metal line overlap and are electrically connected to the first metal resistor strip. The transistor includes a metal gate strip on a same level height as the first metal strip and extends in parallel with the first metal resistor strip.