Localized Airgap Spacers for Reduced Gate Capacitive Coupling
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Solution Overview
Problem
Existing methods for manufacturing spacers with airgaps in semiconductor devices for spin qubits are complex and do not allow for localized airgaps, leading to strong capacitive coupling between adjacent gates.
Innovation Solution
The method involves controlling the aspect ratio between the height of gate stacks and the distance separating them to create localized airgaps by using mechanical-chemical polishing, enabling airgaps to form only at the active region of the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If spacers are made with airgaps to reduce coupling between gates, then capacitive coupling between adjacent gates is reduced, but the manufacturing process becomes complex and airgaps are present over the entire length of the spacer rather than being localized
Solution Approach 1:
The patent applies local quality by creating airgaps only in specific regions of the spacer rather than uniformly throughout. The airgap formation is localized to regions where the gate stack height exceeds a threshold value, allowing different parts of the spacer to have different properties (airgap vs solid material) based on local geometric conditions
Solution Approach 2:
The patent changes physical parameters (gate stack height, spacer thickness, pitch between gates) to control airgap formation. By adjusting the aspect ratio of gate stacks and the thickness of the spacer material, the process exploits parameter thresholds to determine where airgaps form during deposition, transforming a complex manufacturing problem into a parameter-controlled phenomenon
2Quantity of substance
If the pitch between gates is reduced to increase qubit density, then the density of spin qubits increases, but the coupling between adjacent gates becomes stronger
Solution Approach 1:
The patent introduces local airgaps in the spacer material at specific positions where gate stacks are adjacent, creating regions of reduced coupling only where needed. This allows tight overall pitch while maintaining isolation between specific gate pairs through the airgap regions
Solution Approach 2:
The spacer structure becomes a composite of solid dielectric material and air regions. The spacer comprises both solid material (for mechanical support and insulation) and airgaps (for enhanced electrical isolation), allowing the system to achieve both structural integrity and reduced capacitive coupling
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 facilitates the easy manufacture of spacers with localized airgaps, reducing capacitive coupling between gates and enhancing the operational efficiency of semiconductor devices.
Implementation Method 1
a2 is an aspect ratio such that, upon growth of the spacer material forming the spacers, an airgap is in said spacer
Data Source
AI summary
A semiconductor device made on a substrate including an active region and a non-active region at least partially surrounding the active region, a plurality of gate stacks, a part of each gate stack being on the active region, each gate stack being separated from adjacent gate stacks by a spacer by a distance e, the device being such that, for each gate stack, the part of the gate stack located on the active region has a height h2, the part of the same gate stack located on the non-active region has a height h1, and h2/e=a2 and h1/e=a1<alim where a2 is an aspect ratio such that, upon growth of the spacer material forming the spacers, an airgap is in the spacer, and a1 is an aspect ratio such that, upon growth of the spacer material forming the spacers, no airgap is in the spacer.