Hydrogen Thermal-Chemical Copper Surface Treatment
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Solution Overview
Problem
In advanced semiconductor devices, the signal propagation delay is limited by interconnect lines due to increased parasitic line-to-line capacitance and reduced conductivity, and copper-based metallization layers face issues with electromigration, diffusion, and interface stability, which affect device performance and reliability.
Innovation Solution
A thermal-chemical treatment using hydrogen is applied to clean and modify the copper surface before depositing a dielectric cap layer, creating a stable interface with reduced surface damage and controlled copper silicide formation, enhancing electromigration resistance and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plasma-based methods are used to clean copper surface before cap layer deposition, then surface cleaning is achieved, but surface damage occurs and electromigration performance is limited
Solution Approach 1:
The invention changes the fundamental parameter of the cleaning approach from plasma-based to thermal-chemical treatment using hydrogen. This parameter change transforms the cleaning mechanism from a high-energy plasma process that causes surface damage to a controlled thermal-chemical process that cleans without damaging the copper surface, thereby improving electromigration performance while avoiding surface damage.
Solution Approach 2:
The invention replaces the plasma-based cleaning system with a thermal-chemical treatment system using hydrogen. This substitution changes the underlying mechanism from plasma physics to thermal chemistry, where hydrogen diffuses into the copper surface at elevated temperatures to remove contaminants without causing the surface damage associated with plasma treatment, thus resolving the contradiction between cleaning effectiveness and surface integrity.
2Reliability
If conventional plasma-based cap layer formation is used, then copper surface is cleaned, but process time is extended and electromigration performance is suboptimal
Solution Approach 1:
The invention performs preliminary thermal-chemical treatment of the copper surface with hydrogen before cap layer deposition. This preliminary action modifies the copper surface in advance to improve electromigration performance, and the process can be integrated into the deposition chamber, eliminating the need for separate cleaning steps and reducing overall process time compared to conventional plasma-based methods.
Solution Approach 2:
The invention merges the surface treatment and cap layer deposition processes into a single integrated workflow. The thermal-chemical hydrogen treatment is performed in the same chamber and can be transitioned to cap layer deposition without breaking vacuum, combining multiple steps into one continuous process that reduces total process time while improving electromigration performance.
3Reliability
If standard dielectric materials are used with copper metallization, then copper diffusion is prevented, but device performance is limited due to high parasitic capacitance
Solution Approach 1:
The invention introduces a modified copper surface layer as an intermediary between the copper metallization and the dielectric material. The thermal-chemical hydrogen treatment creates a controlled surface modification that acts as a diffusion barrier interface, allowing the use of low-k dielectric materials with reduced parasitic capacitance while maintaining effective copper diffusion prevention through the modified surface layer.
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 improves the electromigration performance by 3-5 times compared to conventional plasma-based methods, reduces process time, and allows for the use of porous and ultra low-k dielectrics, increasing device reliability and throughput.
Implementation Method 1
the exposed surface is cleaned by means of a thermal-chemical treatment in a hydrogen-containing gaseous ambient
Implementation Method 2
the cleaned surface is modified by a thermal treatment on the basis of a silicon-containing precursor
Implementation Method 3
creating a stable interface with reduced surface damage and controlled copper silicide formation
Implementation Method 4
a cap layer is deposited on the exposed surface
Data Source
AI summary
A new technique is disclosed in which a barrier/cap layer for a copper based metal line is formed by using a thermal-chemical treatment based on hydrogen with a surface modification on the basis of a silicon-containing precursor followed by an in situ plasma based deposition of silicon based dielectric barrier material. The thermal-chemical cleaning process is performed in the absence of any plasma ambient.