IC Contact Structure Using Nitridized Molybdenum Against Oxidation
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Solution Overview
Problem
The existing contact metals in integrated circuits (ICs), such as titanium, are prone to oxidation during fabrication steps, leading to degraded electrical performance due to oxidation, and molybdenum, while more conductive, also reacts with oxygen, posing similar challenges.
Innovation Solution
The use of nitridized molybdenum in place of or in conjunction with titanium for forming contacts in IC devices, where a nitridization process introduces nitrogen into the molybdenum surface to reduce dangling bonds and prevent oxidation, forming a refractory and conductive nitridized molybdenum layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If titanium is used as contact metal, then good electrical conductivity is achieved, but oxidation during fabrication degrades performance
Solution Approach 1:
A nitrogen-containing dielectric layer is introduced as an intermediary between the titanium contact metal and the oxidizing environment. This dielectric layer acts as a barrier that prevents oxygen from reaching and oxidizing the titanium, while still allowing the contact to function electrically. The layer is deposited conformally over the contact structure and selectively removed to expose the contact while maintaining the protective nitrogen-rich environment.
Solution Approach 2:
The patent creates a localized inert environment by depositing a nitrogen-containing dielectric layer that releases nitrogen during subsequent processing steps. This nitrogen-rich atmosphere acts as a protective environment that suppresses oxidation of the titanium contact metal during high-temperature fabrication processes, effectively creating an inert atmosphere around the contact structure.
2Reliability
If molybdenum is used as contact metal, then higher conductivity is achieved, but reaction with oxygen creates similar oxidation problems
Solution Approach 1:
The nitrogen-containing dielectric layer serves as a protective intermediary for molybdenum contacts, preventing direct exposure to oxygen during fabrication. This barrier layer allows the molybdenum to maintain its superior conductivity properties without suffering from oxidation issues, as the dielectric layer blocks oxygen access while permitting electrical function.
Solution Approach 2:
By depositing the nitrogen-containing dielectric layer conformally over the molybdenum contact and subsequently removing it selectively, the patent creates a localized nitrogen-rich environment that protects the molybdenum from oxidation during high-temperature processing, enabling the use of this highly conductive material without oxidation penalties.
3Object-affected harmful factors
If contact metal thickness is increased to prevent oxidation, then oxidation resistance improves, but manufacturing complexity increases
Solution Approach 1:
The protection function is segmented from the contact metal itself by introducing a separate nitrogen-containing dielectric layer. Instead of making the contact metal thicker or more complex, the patent divides the system into two functional components: the conductive contact metal and the protective dielectric barrier, simplifying the contact structure while providing effective oxidation protection.
Solution Approach 2:
Rather than modifying the contact metal composition or structure to resist oxidation, the patent introduces an intermediary nitrogen-containing dielectric layer that provides the protection function. This approach maintains the simplicity of the contact metal structure while adding a dedicated protection layer that prevents oxidation without increasing overall device 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 enhances contact performance by reducing oxidation and maintaining high conductivity, resulting in improved electrical conductivity and stability of the contacts during fabrication and operation.
Implementation Method 1
a nitridization process introduces nitrogen into the molybdenum surface to reduce dangling bonds and prevent oxidation, forming a refractory and conductive nitridized molybdenum layer
Data Source
AI summary
Disclosed herein are integrated circuit (IC) devices with contacts using nitridized molybdenum. For example, a contact arrangement for an IC device may include a semiconductor material and a contact extending into a portion of the semiconductor material. The contact may include molybdenum. The molybdenum may be in a first layer and a second layer, where the second layer may further include nitrogen. The first layer may have a thickness between about 5 nanometers and 16 nanometers, and the second layer may have a thickness between about 0.5 nanometers to 2.5 nanometers. The contact may further include a fill material (e.g., an electrically conductive material) and the second layer may be in contact with the fill material. The molybdenum may have a low resistance, and thus may improve the electrical performance of the contact. The nitridized molybdenum may prevent oxidation during the fabrication of the contact.