Backside Gate Cut Replacement Material for Gate Damage Mitigation
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Solution Overview
Problem
Conventional methods for forming gate cut features in semiconductor fabrication are inefficient and can cause damage to the gate structure, leading to performance degradation in field-effect transistors as device sizes decrease.
Innovation Solution
The formation of gate cut features is performed from the backside of the substrate, involving the deposition of a sacrificial material within the trench, followed by filling it with a dielectric material and then replacing it with a work-function metal to repair any damage caused during the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods are used to form gate cut features, then the gate structure can be isolated, but damage is caused to the gate structure leading to performance degradation
Solution Approach 1:
The patent performs the gate cut isolation from the backside of the substrate rather than the front side. This inversion of the processing approach allows the gate cut feature to be formed without directly exposing and damaging the gate structure, as the etching process approaches from the opposite direction through the substrate.
Solution Approach 2:
The patent introduces a replacement material that serves as an intermediary substance to fill the gate cut feature. This replacement material acts as a mediator that protects the gate structure from direct exposure to etchants and processing conditions that would cause damage, while still achieving the desired electrical isolation.
2Productivity
If device size is decreased to increase functional density, then production efficiency increases, but device performance degradation occurs
Solution Approach 1:
The patent transitions from front-side processing to backside processing, adding a dimensional aspect to the gate cut formation process. This dimensional change allows for better control of the isolation process at scaled dimensions, preventing performance degradation while maintaining high functional density through continued miniaturization.
3Reliability
If gate cut feature is formed to isolate gate structure, then short-channel effects are reduced, but damage to gate structure occurs during etching
Solution Approach 1:
By inverting the processing approach and forming the gate cut from the backside, the patent eliminates direct exposure of the gate structure to damaging etchants during the isolation process, while still achieving the necessary electrical separation to control short-channel effects.
Solution Approach 2:
The patent converts the potentially harmful etching process into a beneficial isolation mechanism by performing it from the backside. The same etching process that would normally damage the gate structure is instead used to create clean isolation regions without direct contact with the gate, turning a harmful process into a beneficial one.
Data Source
AI summary
A semiconductor structure includes a substrate, a first gate structure and a second gate structure disposed over the substrate, and an isolation feature extending through the substrate and disposed between the first gate structure and the second gate structure. A top surface of the isolation feature is above a topmost surface of the first gate structure.