Self-Aligned Gate Isolation Using Two-Layer Trench Filling
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Solution Overview
Problem
Conventional fabrication processes for self-aligned gate structures in quantum and semiconductor devices fail to implement intersection elements or terminals while maintaining high gate density, especially in multi-directional layouts, leading to fabrication complexity and processing damage.
Innovation Solution
A method involving the use of two metallic gate layers with distinct gap widths, where a conformal dielectric layer fills smaller gaps completely and larger gaps partially, followed by deposition of a second metallic gate layer and selective etching to create self-aligned gate electrodes, allowing for intersection elements and high gate density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional fabrication processes are used for self-aligned gate structures, then manufacturing simplicity is maintained, but gate density and multi-directional connectivity cannot be achieved
Solution Approach 1:
The gate structure is divided into two separate metallic gate layers (first and second metallic gate layers) with different orientations. The first metallic gate layer contains gate electrodes in a first direction, while the second metallic gate layer contains gate electrodes in a second direction. This segmentation enables multi-directional connectivity and high gate density while maintaining self-alignment through the conformal dielectric layer that fills trenches between gates in each layer independently.
2Adaptability or versatility
If intersection elements are implemented in gate structures, then multi-directional connectivity is achieved, but fabrication complexity increases
Solution Approach 1:
The patent transitions from a single-plane gate structure to a three-dimensional stacked architecture with two metallic gate layers at different vertical levels. The first metallic gate layer is positioned at a first vertical level with gates in a first direction, while the second metallic gate layer is positioned at a second vertical level with gates in a second direction. This dimensional transition enables intersection elements and T-junctions without increasing fabrication complexity, as the conformal dielectric layer automatically provides isolation and alignment for both layers.
3Manufacturing precision
If gate density is increased, then device functionality is improved, but processing damage occurs
Solution Approach 1:
The conformal dielectric layer performs multiple functions automatically: it fills trenches between gate electrodes in the first metallic gate layer, provides electrical isolation, and serves as a template for the second metallic gate layer. This self-aligning mechanism eliminates the need for additional alignment steps and reduces processing complexity, enabling high gate density without increasing processing damage.
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 reduces fabrication complexity and processing damage, enabling reproducible 2D quantum dot arrays and ultra-small pitches in CMOS compatible spin qubit platforms, while maintaining multi-directional connectivity and high gate density.
Implementation Method 1
depositing at least one conformal dielectric layer on the first metallic gate layer, where the at least one conformal dielectric layer completely fills the at least one first trench, and the at least one conformal dielectric layer partially fills the at least one second trench
Data Source
AI summary
One embodiment of the invention provides a method for fabricating a self-aligned gate structure comprising forming at least one first trench having a first width and at least one second trench having a second width in a gate structure comprising a first metallic gate layer. The first width is smaller than the second width. The method comprises depositing at least one conformal dielectric layer on the first metallic gate layer. The dielectric layer completely fills the first trench and partially fills the second trench, such that a portion of the second trench is unfilled. The method comprises depositing a conformal second metallic gate layer on the dielectric layer. The second metallic gate layer fills the unfilled portion of the second trench. The method comprises removing portions of the second metallic gate layer to expose the dielectric layer. Remaining portions of the second metallic gate layer include self-aligned metallic gate electrodes.