Hybrid Self-Aligned Gate Cut for Dense Fin Isolation
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Solution Overview
Problem
As integrated circuits scale down in size, forming semiconductor devices with precise gate cuts to isolate adjacent transistors becomes challenging due to the difficulty in maintaining selectivity during deep etches, especially for high-aspect ratio structures.
Innovation Solution
A hybrid self-aligned gate cut technique is employed, where a first section of the gate cut is self-aligned between adjacent fins before gate patterning, and a second section is formed on the first section after the formation of a sacrificial gate, using a dielectric material that integrates seamlessly with spacer structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If deep etches are used to form gate cuts through high-aspect ratio structures, then gate structures can be isolated between adjacent transistors, but manufacturing precision deteriorates due to difficulty in maintaining selectivity
Solution Approach 1:
The gate cut formation process is divided into two distinct stages: first forming a gate cut trench through the gate dielectric layer, then forming a separate gate cut structure within the trench. This segmentation allows each stage to be optimized independently, improving overall manufacturing precision while achieving reliable gate isolation.
Solution Approach 2:
The gate cut trench is formed preliminarily before the gate electrode is deposited. This preliminary action creates a predefined isolation structure that guides subsequent processing steps, ensuring consistent positioning and dimensions without requiring high-aspect ratio deep etches through the entire gate structure.
2Productivity
If transistors are packed more densely to reduce device size, then circuit integration is improved, but device structure formation becomes more challenging
Solution Approach 1:
The gate cut structure is segmented into a trench portion and a filled structure portion, allowing the isolation features to be formed with relaxed dimensional constraints. This enables tighter transistor spacing while maintaining manufacturability of the isolation structures.
Solution Approach 2:
A dielectric material is used as an intermediary substance to form the gate cut structure within the trench. This intermediary material provides the necessary isolation properties while allowing flexible positioning and sizing that accommodates dense transistor packing.
3Measurement precision
If self-aligned gate cuts are formed before gate patterning, then alignment accuracy is improved, but process complexity increases
Solution Approach 1:
The alignment process is segmented into two steps: first aligning the gate cut trench with the gate dielectric layer, then aligning the gate cut structure with the trench. This segmentation simplifies each alignment step while achieving high overall alignment accuracy.
Solution Approach 2:
The gate cut trench is formed preliminarily with alignment features that guide subsequent gate patterning. This preliminary alignment structure reduces the complexity of final gate alignment by providing predetermined reference points.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
Techniques are provided herein to form semiconductor devices that include one or more self-aligned gate cuts having a hybrid architecture between adjacent devices. In an example, a semiconductor device includes a gate structure around or otherwise on a semiconductor region (also referred to as a channel region). The gate structure may be interrupted between two transistors with a gate cut that extends through at least an entire thickness of the gate structure and includes dielectric material. The gate cut includes a hybrid design that is formed in two parts. A first part of the gate cut is formed prior to any gate patterning and is self-aligned between adjacent fins of semiconductor material. A second part of the gate cut is formed over the first part of the gate cut and is integrated with spacer structures formed on the sidewalls of a sacrificial gate that extends over the adjacent fins.