Molybdenum Plug Passivation Against Nitridation and Oxidation
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Solution Overview
Problem
Conventional MOL interconnects using molybdenum as a metal fill layer in semiconductor devices face issues with oxidation and nitridation due to exposure to nitrogen and oxygen-containing process gases, leading to increased resistance and reduced performance.
Innovation Solution
A passivation layer is formed over the metal fill material using a soaking process with specific precursor gases to prevent oxidation and nitridation, followed by a chemical mechanical polishing process to planarize the structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If molybdenum is used as metal fill layer to replace tungsten, then resistivity is reduced in smaller features, but oxidation and nitridation occur due to exposure to nitrogen and oxygen-containing process gases, leading to increased resistance
Solution Approach 1:
A passivation layer is deposited over the molybdenum fill layer to act as an intermediary protective barrier. This passivation layer prevents direct contact between the molybdenum and harmful process gases (nitrogen and oxygen), thereby preventing oxidation and nitridation while allowing the molybdenum to maintain its low resistivity properties
Solution Approach 2:
The passivation layer creates an inert protective environment over the molybdenum fill layer, isolating it from reactive process gases. This inert barrier prevents chemical reactions (oxidation and nitridation) that would otherwise increase resistance and degrade performance
2Ease of manufacture
If conventional MOL interconnect formation is performed without passivation, then manufacturing process is simpler, but resistance increases due to nitridation and oxidation of the metal fill layer surface
Solution Approach 1:
The passivation layer is deposited preliminarily over the molybdenum fill layer before subsequent processing steps. This preliminary protective action ensures that the metal fill layer is already protected from oxidation and nitridation that would occur during later exposure to nitrogen and oxygen-containing process gases
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
The passivation layer effectively prevents oxidation and nitridation of the molybdenum fill layer, maintaining low contact resistance and enhancing the overall performance of the semiconductor device.
Implementation Method 1
performing a soaking process on the semiconductor device structure to form a passivation layer over a surface of the metal fill material... The passivation layer effectively prevents oxidation and nitridation of the molybdenum fill layer
Implementation Method 2
process gases, such as nitrogen or ammonia (NH3), cause nitridation and oxidation of the surfaces of the formed Mo metal fill layer... The passivation layer effectively prevents oxidation and nitridation of the molybdenum fill layer
Data Source
AI summary
A method includes forming a metal fill material on at least one electrical connection formed in a feature formed within a dielectric layer of a semiconductor device structure. The metal fill material partially fills the feature, the partially filled feature comprises the metal fill material and an exposed first portion of a sidewall of the feature that comprises the material of the dielectric layer, and a gap region formed between a second portion of the sidewall and a sidewall of the metal fill material, and performing a soaking process on the semiconductor device structure to form a passivation layer over a surface of the metal fill material and including a portion of the metal fill material disposed within the gap.