Linerless Stacked Contacts for Semiconductor Devices
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Solution Overview
Problem
Liners in semiconductor devices increase resistance and impair current transfer between stacked contacts, leading to reduced efficiency and performance in device operation.
Innovation Solution
A method of forming stacked contacts with a metal-to-metal interface by depositing a barrier on sacrificial material within contact vias, allowing conductive material to fill and form contacts without a liner, and subsequently removing the sacrificial material to reduce resistance and improve isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a liner is deposited around contacts to improve isolation between regions, then isolation between regions is improved, but resistance increases and current transfer between stacked contacts deteriorates
Solution Approach 1:
The liner is segmented into two distinct parts: a first liner portion deposited on the sidewalls of the contact via, and a second liner portion (sacrificial material) filling the bottom of the contact via. This segmentation allows the first liner portion to provide isolation while the second portion is removed to maintain low-resistance electrical contact, thus resolving the contradiction between isolation and current transfer.
Solution Approach 2:
The sacrificial material (second liner portion) is selectively removed from the bottom of the contact via after the conductive material is deposited. This extraction eliminates the resistance-causing element at the critical contact interface while preserving the isolation function of the first liner portion on the sidewalls, thereby resolving the contradiction between isolation and low resistance.
2Reliability
If a liner is deposited around contacts to improve isolation, then isolation between regions is improved, but switching performance deteriorates due to increased resistance
Solution Approach 1:
The liner is divided into a first liner portion on sidewalls for isolation and a second liner portion at the bottom that is removed. This segmentation ensures that isolation is maintained where needed (sidewalls) while resistance is minimized at the contact interface (bottom), thereby improving switching performance without sacrificing isolation.
Solution Approach 2:
The sacrificial material is selectively extracted from the contact via bottom after serving its purpose as a placeholder during deposition. This removal eliminates the resistance barrier that would otherwise degrade switching performance, while the remaining first liner portion continues to provide region isolation.
3Manufacturing precision
If a barrier is selectively deposited on sacrificial material, then the barrier lines the contact via sidewalls while contacts remain exposed, but the process complexity increases
Solution Approach 1:
The sacrificial material serves as an intermediary substrate that enables selective deposition of the barrier. By depositing the barrier on the sacrificial material rather than directly on the contact via walls, the process achieves precise lining while the sacrificial material can be later removed, managing the complexity through a temporary intermediate element.
Solution Approach 2:
The sacrificial material is deposited in advance to create a defined surface for barrier deposition. This preliminary action establishes the geometric framework that guides the selective barrier deposition process, ensuring precision while the sacrificial material is subsequently removed to reduce overall process complexity.
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 power draw and enhances switching performance by eliminating liner-induced resistance and improving current transfer between contacts.
Implementation Method 1
Sides of the at least one contact via are lined by selectively depositing a barrier on the sacrificial material
Data Source
AI summary
Semiconductor devices and methods for forming semiconductor devices include opening at least one contact via through a sacrificial material down to contacts. Sides of the at least one contact via are lined by selectively depositing a barrier on the sacrificial material, the barrier extending along sidewalls of the at least one contact via from a top surface of the sacrificial material down to a bottom surface of the sacrificial material proximal to the contacts such that the contacts remain exposed. A conductive material is deposited in the at least one contact via down to the contacts to form stacked contacts having the hard mask on sides thereof. The sacrificial material is removed.