Double Nitride Barrier Layer Sets for Semiconductor Contacts
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Solution Overview
Problem
High temperature annealing in semiconductor fabrication degrades titanium nitride barrier layers, leading to cracks and ineffective protection during tungsten deposition, resulting in volcano defects in contact openings.
Innovation Solution
A double barrier layer set is implemented, where a first nitride barrier layer is deposited, followed by annealing to form a silicide region, and then a second metal and nitride barrier layer are deposited on top, preventing exposure to high temperatures and thus maintaining barrier integrity during tungsten fluoride chemical vapor deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high temperature annealing is performed to form silicide region, then electrical contact quality is improved, but nitride barrier layer degrades and cracks forming
Solution Approach 1:
The single nitride barrier layer is segmented into two separate layers: a first nitride barrier layer deposited before annealing and a second nitride barrier layer deposited after annealing. The first layer provides initial protection and is positioned to benefit from the annealing process, while the second layer is deposited afterward to provide fresh protection without exposure to degrading high temperatures, thus resolving the contradiction between achieving good electrical contact and maintaining barrier layer integrity.
2Reliability
If high temperature annealing is performed, then silicide region forms improving contact, but fluorine attack occurs through degraded barrier layer
Solution Approach 1:
The first nitride barrier layer is deposited in advance before the high temperature annealing process to provide initial protection during silicide formation. Then, after the annealing is complete and the temperature has been reduced, a second nitride barrier layer is deposited to provide fresh protection before the tungsten fluoride chemical vapor deposition process. This sequential approach ensures that protective barriers are in place at the appropriate times to prevent fluorine attack while still achieving good electrical contact.
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 prevents the degradation of nitride barrier layers, eliminating volcano defects and ensuring effective protection against fluorine attack, resulting in improved contact quality and reduced resistance.
Implementation Method 1
annealing after depositing the first nitride layer to form a silicide region in a junction area underlying the contact opening with the first metal layer and the semiconductor substrate
Implementation Method 2
form a silicide region
Implementation Method 3
forming tungsten in a remaining portion of the contact opening using chemical vapor deposition using tungsten fluoride
Data Source
AI summary
Methods of forming a contact for a semiconductor device with double barrier layer sets, and a device so formed are disclosed. Methods may include: depositing a first metal layer contacting a semiconductor substrate in a contact opening; depositing a first nitride barrier layer on the first metal layer; and annealing after depositing the first nitride barrier layer to form silicide region in a junction area underlying the contact opening with the first metal layer and the semiconductor substrate. After the annealing, a second metal layer may be deposited, followed by a second nitride barrier layer. A conductor is formed in a remaining portion of the contact opening. The double barrier layer sets prevent the formation of volcano defects and also advantageously reduce contact resistance.