Alkaline Post-CMP Cleaning Chemistry for Copper Interconnects
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current alkaline cleaning solutions for semiconductor substrates after Chemical Mechanical Planarization (CMP) fail to effectively remove residual metals, protect metal surfaces from corrosion, and prevent contamination, often requiring multiple steps and handling additional chemicals, which can lead to corrosion, oxidation, and surface residue issues.
Innovation Solution
A cleaning solution comprising tetra alkyl ammonium hydroxide as a cleaning agent, a mixture of gluconic acid and isopropanolamine as a chelating agent, and propyl gallate as a corrosion-inhibiting compound, designed to operate within an alkaline pH range to efficiently remove particles and prevent metal re-deposition and corrosion in a single step.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If alkaline cleaning solutions are used to remove residual metals, then cleaning effectiveness is improved, but metal surface corrosion increases
Solution Approach 1:
A corrosion-inhibiting compound is introduced as an intermediary substance that mediates between the alkaline cleaning solution and the metal surface. This compound forms a protective layer on the metal surface, allowing the alkaline solution to remove residual metals effectively while preventing direct corrosive interaction between the cleaning solution and metal surface.
Solution Approach 2:
The cleaning solution is formulated as a composite chemistry containing multiple components: alkaline agents for cleaning, chelating agents for metal complexation, and corrosion-inhibiting compounds for surface protection. This composite formulation enables simultaneous achievement of effective metal removal and corrosion prevention that single-component solutions cannot achieve.
2Manufacturing precision
If multiple cleaning steps and additional chemicals are used, then cleaning thoroughness is improved, but process complexity increases
Solution Approach 1:
Multiple cleaning functions (metal removal, corrosion inhibition, oxidation prevention) that traditionally required separate steps and chemicals are merged into a single integrated cleaning solution. This multi-functional formulation achieves thorough cleaning in one step while eliminating the need for additional processing steps and chemical handling.
Solution Approach 2:
The cleaning solution is designed with universal multi-functionality, where a single chemical formulation performs multiple roles: acting as a cleaning agent for residual metal removal, a corrosion inhibitor for surface protection, and an oxidation preventer. This eliminates the need for specialized separate steps for each function.
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 solution effectively removes residual metals, prevents corrosion and oxidation, and maintains surface cleanliness without additional steps, enhancing semiconductor device performance by reducing static etch rates and surface roughness, while avoiding contamination and pH-related equipment issues.
Implementation Method 1
Chemicals that can complex the residual metal in the cleaning solution are effective cleaning agents because the residual metals are not re-deposited on the semiconductor work-piece after they are removed
Implementation Method 2
A 'corrosion-inhibiting compound' is the component of the cleaning solution that protects the metal surface from attack by mechanisms such as the aggressive nature of the cleaning solution, oxidation, post cleaning corrosion, galvanic attack, or photo-induced attack
Data Source
AI summary
This disclosure discusses cleaning of semiconductor wafers after the Chemical-Mechanical Planarization (CMP) of the wafer during the manufacturing of semiconductor devices. Disclosed is an alkaline chemistry for the post-CMP cleaning of wafers containing metal, particularly copper, interconnects. Residual slurry particles, particularly copper or other metal particles, are removed from the wafer surface without significantly etching the metal, leaving deposits on the surface, or imparting significant contamination to the wafer while also protecting the metal from oxidation and corrosion. Additionally, at least one strong chelating agent is present to complex metal ions in solution, facilitating the removal of metal from the dielectric and preventing re-deposition onto the wafer.