Gate Cut Grid Layout for Isolated IC Gates With Lower Parasitic Capacitance
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Solution Overview
Problem
The challenge in integrated circuit fabrication lies in forming gate cut structures between adjacent semiconductor devices, which requires additional masking and etching processes, potentially compromising the integrity of the circuit and leading to issues like parasitic capacitance due to standard gate cut structures being contained within the gate trench area, causing potential shorting.
Innovation Solution
A technique is developed to form a grid of gate cut structures across an integrated circuit, where each gate cut structure is formed simultaneously between adjacent pairs of semiconductor devices, utilizing conformal sidewall spacer structures that wrap around the ends of gate structures to provide enhanced isolation and reduce dead space, thereby simplifying the masking and etching process and lowering parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard gate cut structures are used within the gate trench area, then the gate structures are isolated, but parasitic capacitance increases and potential shorting occurs
Solution Approach 1:
The gate cut structures are moved from the traditional within-trench configuration to a between-trench configuration, utilizing the space between adjacent gate trenches. This dimensional relocation eliminates the parasitic capacitance issue while maintaining isolation functionality, as the cut structures now sit in the isolation dielectric material between trenches rather than within the conductive trench area.
2Reliability
If additional masking and etching processes are used to form gate cut structures, then gate structures are isolated, but device complexity and fabrication difficulty increase
Solution Approach 1:
The formation of gate cut structures is merged with the existing gate trench formation process. The same masking and etching steps used to create the gate trenches also simultaneously create the gate cut structures between adjacent trenches. This integration eliminates additional process steps while achieving the isolation function, as the cut structures are formed as a byproduct of the trench definition process.
3Reliability
If gate cut structures are formed between adjacent semiconductor devices, then isolation is enhanced, but manufacturing precision requirements increase due to tight alignment tolerances
Solution Approach 1:
The gate cut structures self-align to the gate trenches through the fabrication process geometry. As the masking layers and etching processes define the trench locations, the cut structures automatically position themselves between the trenches without requiring separate alignment steps. This self-alignment mechanism eliminates the need for tight alignment tolerances, as the structures define each other's positions through the process geometry rather than requiring independent precision placement.
Data Source
AI summary
Techniques are provided herein to form an integrated circuit having a grid of gate cut structures such that a gate cut structure exists between pairs of semiconductor devices. In an example, neighboring semiconductor devices each include a semiconductor region extending between a source region and a drain region, and a gate structure extending over the semiconductor regions of the neighboring semiconductor devices. A gate cut structure is present between each pair of neighboring semiconductor devices thus interrupting the gate structure and isolating the gate of one semiconductor device from the gate of the other semiconductor device. Each of the gate cut structures may be formed at the same time in a grid-like pattern across the integrated circuit (or a portion thereof). Sidewall spacer structures on the sidewalls of the gate structure wrap around ends of each gate structure to form a given gate cut structure.