Spin Qubit Gate Array Contacting With Sidewall Spacer Isolation
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Solution Overview
Problem
Contacting closely spaced gates in quantum dot devices is challenging due to misalignment errors in traditional damascene-type methods, leading to shorting risks.
Innovation Solution
A method involving separate process steps for forming electrical connections to gate structures, using conformal dielectric layers to form spacers on sidewalls, ensuring isolation despite misalignment, by embedding conductive lines in dielectric material and using selective etching to maintain spacer integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional damascene-type methods are used to produce conductive vias and lines, then the manufacturing process is simpler, but overlay errors occur having the same order of magnitude as the gate interspacing, leading to unacceptable misalignment errors and risk of shorting
Solution Approach 1:
The patent divides the gate array into alternating first and second type gates, and separately forms conductive lines for each type in separate process step sequences. This segmentation allows independent optimization of alignment for each gate type without affecting the other, thereby improving manufacturing precision while managing process complexity through systematic organization
Solution Approach 2:
The patent introduces conformal dielectric layers as intermediary structures between conductive lines of different gate types. These conformal layers act as protective spacers that physically separate the conductive lines, preventing shorting even when alignment errors occur, thus improving manufacturing precision through an intermediary protective structure
2Area of stationary object
If gates are closely spaced to increase device density, then the quantum dot device functionality is improved, but contacting the gates becomes challenging due to misalignment errors and shorting risks
Solution Approach 1:
Conformal dielectric layers are introduced as intermediary protective structures between closely spaced conductive lines. These layers follow the topography of the conductive lines and provide physical separation, preventing shorting while allowing the conductive lines to be placed closer together, thereby maintaining contact reliability despite increased device density
Solution Approach 2:
The patent moves from a two-dimensional planar separation approach to a three-dimensional conformal wrapping approach. The conformal dielectric layers wrap around the conductive lines in three dimensions, providing protection against misalignment and shorting from multiple angular directions, not just in the planar direction
3Reliability
If conformal dielectric layers are formed on conductive lines, then protective spacers are created to prevent shorting, but the manufacturing process complexity increases
Solution Approach 1:
The conformal dielectric layers are formed using self-aligned processes where the deposition automatically follows the topography of the conductive lines. This self-service approach eliminates the need for additional alignment steps and manual positioning, reducing process complexity while maintaining the protective function against shorting
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
Ensures reliable electrical connections without shorting, even with misalignment, by using conformal dielectric spacers to isolate conductive lines, enhancing the reliability of quantum dot devices.
Implementation Method 1
producing a conformal dielectric layer on the sidewalls and the top surface of the first conductive lines
Data Source
Figure 1~3
Figure 4~6
Figure 7a~10
AI summary
An array of gate structures (3,4) is produced on a planar surface (1), said array being suitable for the production of a spin qubit quantum dot device. The gate structures include alternately arranged structures of a first and second type, such as plunger gates (3) and barrier gates (4). According to the invention, electrical connections to the gate structures of the first and second type are produced in separate process step sequences. The connections to the first gate type include the formation of first conductive lines (17) running essentially parallel to the planar surface and connected to the gate structures of the first type by first via connections (18). Before producing similar connections to the gate structures of the second type, a conformal dielectric layer (25) is formed on the first conductive lines (17), i.e. on a top surface and on sidewalls of said first conductive lines. The conformal layer (25) is configured so that it forms a protective spacer on the sidewalls of the first conductive lines (17) during processing of the second conductive lines (39), so that shorting between the conductive lines is avoided.