Multigate Gate Isolation Fins for Denser Transistor Packing
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Solution Overview
Problem
Non-self-aligned gate cutting techniques in multigate devices hinder dense packing of IC features due to process variations, leading to increased spacing between active device areas and reduced packing density.
Innovation Solution
Implementing self-aligned gate cutting techniques that form metal gate isolation structures early in the fabrication process, allowing for smaller spacings between active device areas and enabling more compact transistor packing by eliminating the need to account for lithography process variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If non-self-aligned gate cutting techniques are used, then gate isolation can be achieved, but spacing between active device areas must be increased to account for lithography process variations, reducing packing density
Solution Approach 1:
The gate isolation structures are formed early in the fabrication process, before the active device areas are defined. This preliminary formation allows the isolation structures to serve as alignment references for subsequent lithography steps, eliminating the need to add extra spacing for process variations.
Solution Approach 2:
The gate isolation structures are designed to be self-aligned to the active device areas through the fabrication process. The isolation structures automatically position themselves relative to the active devices without requiring additional alignment margins, enabling the structures to self-correct for process variations.
2Manufacturing precision
If non-self-aligned gate cutting techniques are used, then gate isolation can be achieved, but packing density of transistors and IC pattern density decrease
Solution Approach 1:
By forming gate isolation structures early in the fabrication sequence, before active device definition, the patent enables tighter packing of transistors. The preliminary isolation structures do not interfere with subsequent device formation and allow maximum density without compromising isolation quality.
3Manufacturing precision
If spacing between active device areas is increased to account for lithography process variations, then manufacturing precision can be maintained, but area occupied by each device increases
Solution Approach 1:
The gate isolation structures are designed to automatically align with active device areas through the fabrication process sequence. This self-alignment mechanism eliminates the need for design margins, allowing devices to be packed at minimum spacing while maintaining precision through the self-correcting nature of the process.
Data Source
AI summary
Gate cutting techniques disclosed herein form gate isolation fins to isolate metal gates of multigate devices from one another before forming the multigate devices, and in particular, before forming the metal gates of the multigate devices. An exemplary device includes a first multigate device having first source/drain features and a first metal gate that surrounds a first channel layer and a second multigate device having second source/drain features and a second metal gate that surrounds a second channel layer. A gate isolation fin, which separates the first metal gate and the second metal gate, includes a first dielectric layer having a first dielectric constant and a second dielectric layer having a second dielectric constant disposed over the first dielectric layer. The second dielectric constant is less than the first dielectric constant. A gate isolation end cap may be disposed on the gate isolation fin to provide additional isolation.