Copper Interconnect Ru Layer CMP Corrosion Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The introduction of a Ruthenium (Ru)-containing layer in copper interconnect structures can deteriorate the quality and performance of Cu interconnects due to potential differences in activity between Cu and Ru, leading to etching issues during chemical mechanical polishing (CMP) processes.
Innovation Solution
Incorporating a Cu-corrosion-inhibitor into the polishing slurry during CMP steps to reduce the etching of Cu and improve the quality and performance of the Cu interconnect structure, while using multiple CMP steps with specific slurry compositions and pad types to control the thickness and flatness of the Cu and Ru layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Ruthenium (Ru)-containing layer is introduced in copper interconnect structures, then the adhesion and conductivity are improved, but the quality and performance deteriorate due to etching issues during CMP processes
Solution Approach 1:
A titanium nitride (TiN) barrier layer is introduced as an intermediary between the Ru-containing layer and the Cu layer. This mediator prevents direct interaction between Ru and Cu during CMP processes, eliminating the etching issues caused by the activity difference between these two metals while preserving the adhesion benefits of the Ru layer.
Solution Approach 2:
The patent converts the harmful etching effect caused by the activity difference between Ru and Cu into a beneficial selective removal process. By controlling the CMP parameters and using the TiN barrier, the Ru layer can be selectively removed where needed while protecting the Cu interconnect structure from damage, turning a potential defect into a useful process feature.
2Manufacturing precision
If multiple CMP steps are performed to control layer thickness and flatness, then the manufacturing precision is improved, but the process complexity increases
Solution Approach 1:
The CMP process is segmented into multiple distinct steps, each with specific objectives: a first CMP step for initial planarization and thickness reduction, and a second CMP step for final precision control and flatness achievement. This segmentation allows each step to be optimized independently, improving overall precision while making the complex process more manageable and controllable.
Solution Approach 2:
The patent employs parameter changes between CMP steps, including variations in slurry composition, polishing pad hardness, downforce, and rotation speed. By systematically changing these parameters between steps, the process achieves different objectives at each stage - aggressive material removal initially, then precise thickness control and flatness optimization in subsequent steps.
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 use of Cu-corrosion-inhibitors in the CMP process minimizes corrosion and etching issues, enhancing the quality and performance of Cu interconnects, and the multi-step CMP approach ensures precise control over layer thickness and flatness, thereby improving the semiconductor structure's electrical properties and yield.
Implementation Method 1
performing a first chemical mechanical polishing (CMP) step to remove a first partial thickness of the Copper (Cu)-containing layer
Implementation Method 2
performing a second CMP step using a polishing slurry containing a Cu-corrosion-inhibitor to remove a second partial thickness of the Copper (Cu)-containing layer above the Ruthenium (Ru)-containing layer
Data Source
AI summary
Semiconductor structures and fabrication methods are provided. An exemplary fabrication method includes providing a base substrate; forming a dielectric layer having an opening on the base substrate; forming a Ruthenium (Ru)-containing layer on side surfaces and a bottom of the opening and on a top surface of the dielectric layer; forming a Copper (Cu) containing layer to fill the opening and cover the Ruthenium (Ru)-containing layer; performing a first chemical mechanical polishing (CMP) step to remove a first partial thickness of the Copper (Cu)-containing layer; performing a second CMP step using a polishing slurry containing a Cu-corrosion-inhibitor to remove a second partial thickness of the Copper (Cu)-containing layer above the Ruthenium (Ru)-containing layer; and performing a third CMP step using a polishing slurry containing a Cu-corrosion-inhibitor to remove a third partial thickness of the Copper (Cu)-containing layer above the dielectric layer.