SADP Gate Protrusion Layout Using Notched Mandrels
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Solution Overview
Problem
Existing self-aligned double patterning processes face challenges in forming complex feature layouts and efficient transfer of patterns to underlying layers in semiconductor fabrication, particularly in creating protrusions and gate structures for field-effect transistors.
Innovation Solution
A method involving the formation of notches in mandrels, followed by spacer deposition and selective etching to create protrusions and gates, allowing for self-aligned double patterning with improved layout complexity and efficient pattern transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional self-aligned double patterning processes are used to form gate structures, then the basic gate pattern can be formed, but the layout flexibility is limited and dummy gates are required
Solution Approach 1:
The gate structure is segmented into multiple components: a main gate body and laterally projecting protrusions. The protrusions are formed by patterning notches in the mandrel before spacer deposition, allowing the gate to be divided into functional segments that provide both flexibility and electrical connection points without requiring dummy gates
Solution Approach 2:
Notches are patterned in the mandrel before spacer formation, creating predetermined regions that will become the protrusions. This preliminary action defines the final gate structure geometry early in the process, enabling layout flexibility to be built into the structure before subsequent processing steps
2Adaptability or versatility
If complex feature layouts are formed using existing self-aligned double patterning, then more layout options are available, but the process complexity and difficulty increase
Solution Approach 1:
The spacer material automatically fills the notches in the mandrel during deposition, and the spacer width is self-determined by the notch dimensions and deposition thickness control. This self-service mechanism creates complex protrusion features without requiring additional patterning steps or complex process control
Solution Approach 2:
The process extends from two-dimensional mandrel patterning to three-dimensional gate structures by forming notches that penetrate partially through the mandrel thickness, then filling with spacer material that creates laterally projecting protrusions. This dimensional transition enables complex layouts while maintaining process simplicity
3Area of stationary object
If protrusions are formed laterally from the gate, then pin accessibility and area usage are improved, but the patterning process becomes more difficult
Solution Approach 1:
The mechanical challenge of directly patterning lateral protrusions is replaced by a chemical deposition process. The spacer material is deposited conformally on the mandrel surfaces, automatically forming the protrusions through vapor-phase deposition rather than mechanical lithography and etching
Solution Approach 2:
The protrusion dimensions are controlled by changing deposition parameters (spacer material thickness, deposition rate, temperature) rather than relying on lithographic resolution. This parameter change approach allows precise control of protrusion size and shape while maintaining manufacturing simplicity
Data Source
AI summary
Structures with features formed by self-aligned double patterning and methods of self-aligned multiple patterning. The structure comprises a first field-effect transistor including a first gate and a first protrusion projecting laterally from the first gate, and a second field-effect transistor including a second gate and a second protrusion projecting laterally from the second gate. The second gate and the second protrusion are spaced in a lateral direction from the first gate and the first protrusion. The structure further comprises a gate contact connecting the first protrusion of the first gate to the second protrusion the second gate.