CFET Isolation Structure to Eliminate Dummy Cell Capacitance
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Solution Overview
Problem
In complementary field-effect transistor (CFET) architecture, the imbalance between P-type and N-type devices leads to the use of skew cells, where some devices become non-functional 'dummy devices' due to differences in numbers, resulting in undesired extra cell capacitors.
Innovation Solution
The implementation of an isolation layer to prevent the formation of non-functional source/drain structures during epitaxial growth, replacing them with insulation structures that do not capacitive couple with surrounding elements, thereby reducing unwanted cell capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If skew cells are used to balance P-type and N-type devices, then device operation balance is improved, but dummy devices are created forming undesired cell capacitors
Solution Approach 1:
The patent extracts and removes the harmful capacitive coupling effect by introducing an isolation layer that electrically isolates the dummy device from surrounding elements, thereby eliminating the undesired cell capacitors while maintaining the skew cell structure for device balancing
Solution Approach 2:
The isolation layer acts as an intermediary element between the dummy device and surrounding conductive elements, preventing direct capacitive coupling and eliminating the harmful effect of undesired cell capacitors
2Stability of the object's composition
If dummy devices are formed in skew cells, then device count balance is achieved, but extra cell capacitors are induced
Solution Approach 1:
The patent extracts the harmful capacitive effect by removing the electrical coupling path between dummy devices and surrounding elements through the isolation layer, thereby eliminating extra cell capacitors while preserving the balanced device composition
Solution Approach 2:
The isolation layer serves as a mediating structure that maintains the physical presence of dummy devices for compositional balance while preventing their harmful capacitive interaction with surrounding elements
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 effectively reduces undesired cell capacitors in semiconductor devices by isolating channels and forming insulation structures instead of non-functional source/drain structures, enhancing device performance.
Implementation Method 1
preventing the formation of dummy source/drain structures during epitaxial growth
Data Source
AI summary
A method includes: forming a first channel structure through a first gate structure; forming a first source/drain structure coupled to the first channel structure at a first surface of the first gate structure; before the first source/drain structure is formed, forming a first isolation layer at a second surface of the first gate structure to isolate the first channel structure; and after the first source/drain structure is formed, forming a first insulation structure at a position of the first isolation layer. The first surface and the second surface are opposite to each other, and a size of the first insulation structure is equal to or larger than a size of the first source/drain structure.