Bottom-Up Contact Plug Formation Using Nitrided Trench Bases
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Solution Overview
Problem
The existing processes for forming source/drain contact plugs in integrated circuits face challenges in achieving seamless and efficient connections due to issues with the formation of metal nitride layers and the subsequent deposition of metal, leading to potential gaps and inefficiencies in the contact plugs.
Innovation Solution
The method involves depositing a metal layer, nitriding its surface to form a metal nitride layer, oxidizing it, and then selectively removing the oxide to leave portions at the contact openings' bottoms, which serves as a base for a bottom-up deposition of metal, ensuring seamless contact plugs without the need for additional adhesion layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal layer is deposited and nitridated to form a metal nitride layer, then adhesion is improved, but gaps and inefficiencies occur in the contact plugs due to incomplete coverage
Solution Approach 1:
Instead of depositing metal from top to bottom, the patent performs bottom-up deposition where metal is deposited from the bottom of the contact opening upward. This inversion of the deposition direction ensures that the metal layer continuously covers the substrate and previously formed layers, preventing gaps and achieving seamless contact plugs while maintaining adhesion.
Solution Approach 2:
The patent performs preliminary nitridation of the metal layer to form a metal nitride layer with improved adhesion properties before completing the contact plug formation. This preliminary action ensures that the metal layer has enhanced bonding capability to the substrate and subsequent layers, addressing adhesion requirements before the final plug structure is completed.
2Reliability
If additional adhesion layers are deposited to improve connectivity, then reliability is enhanced, but manufacturing complexity increases
Solution Approach 1:
The metal layer in the patent serves multiple functions: it provides structural integrity as the contact plug body, ensures adhesion to the substrate through nitridation, and maintains electrical connectivity. By making the metal layer multi-functional, the patent eliminates the need for separate adhesion layers, thereby enhancing reliability without increasing manufacturing complexity.
Solution Approach 2:
The patent combines the adhesion function with the metal layer itself by performing nitridation to create a metal nitride layer. This merging of adhesion functionality into the existing metal layer structure eliminates the need for additional separate adhesion layers, reducing manufacturing complexity while maintaining improved connectivity and reliability.
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 results in seam-free, efficient contact plugs with improved connectivity and reduced manufacturing complexity, enhancing the overall performance and reliability of integrated circuits.
Implementation Method 1
nitriding its surface to form a metal nitride layer
Implementation Method 2
oxidizing it
Implementation Method 3
filling a metallic material into the trench using a bottom-up deposition process
Data Source
AI summary
A method includes etching a dielectric layer to form a trench in the dielectric layer, depositing a metal layer extending into the trench, performing a nitridation process on the metal layer to convert a portion of the metal layer into a metal nitride layer, performing an oxidation process on the metal nitride layer to form a metal oxynitride layer, removing the metal oxynitride layer, and filling a metallic material into the trench using a bottom-up deposition process to form a contact plug.