Post-CMP Cleaning Composition for Cobalt Substrates
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Solution Overview
Problem
Current post-CMP cleaning compositions are inadequate for efficiently removing residues and contaminants from cobalt or cobalt alloy substrates without damaging the semiconductor materials, which is crucial for maintaining device reliability and preventing defects in microelectronic devices.
Innovation Solution
A post-CMP cleaning composition comprising polyethylene glycol (PEG) with a specific mass average molar mass range, an anionic polymer such as poly(acrylic acid) or acrylic acid-maleic acid copolymer, and water, with a pH between 7.0 and 10.5, which effectively removes contaminants without harming cobalt or cobalt alloy layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional post-CMP cleaning compositions are used, then general cleaning capability is maintained, but they are inadequate for efficiently removing residues from cobalt or cobalt alloy substrates without damaging semiconductor materials
Solution Approach 1:
The invention changes the chemical parameters of the cleaning composition by specifying a pH range of 2.0-4.0 (acidic condition) and using particular concentrations of H2O2 (0.1-5% wt) and NH4OH (0.1-5% wt). This parameter optimization enables effective removal of cobalt residues while protecting semiconductor materials, resolving the contradiction between cleaning efficiency and material safety.
Solution Approach 2:
The cleaning composition uses a composite formulation combining H2O2, NH4OH, and water in specific ratios. This composite approach creates a synergistic effect where the combination of oxidizing agent (H2O2) and base (NH4OH) at controlled pH provides both strong cleaning capability for cobalt residues and gentleness toward semiconductor materials, simultaneously achieving high productivity and reliability.
2Productivity
If stronger cleaning agents are used to improve contaminant removal, then cleaning efficiency increases, but damage to semiconductor materials may occur
Solution Approach 1:
The invention optimizes the pH parameter to a specific acidic range (2.0-4.0) and controls the concentrations of active ingredients (H2O2: 0.1-5% wt, NH4OH: 0.1-5% wt). This precise parameter control enables strong cleaning action against cobalt residues while the buffered acidic environment protects semiconductor materials from damage, resolving the contradiction between cleaning strength and material safety.
Solution Approach 2:
The NH4OH acts as an intermediary substance that buffers the H2O2 oxidizing agent. The combination creates a controlled acidic environment that mediates between the strong cleaning power needed for cobalt residue removal and the gentleness required to protect semiconductor materials, preventing direct harsh interaction between the oxidizer and sensitive materials.
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 composition efficiently removes post-CMP residues and contaminants from cobalt or cobalt alloy substrates, ensuring the integrity and reliability of semiconductor devices while being environmentally benign and easy to use.
Implementation Method 1
The CMP process itself typically involves holding and rotating a thin, flat (e.g patterned) substrate of the semiconductor device against a wetted polishing pad under controlled pressure and temperature in the presence of CMP slurries. The CMP slurries contain abrasive materials and various chemical additives as appropriate to the specific CMP process and requirements. At the end of the CMP process, contaminants and residues comprising particles from the CMP slurries, added chemicals, and reaction by-products remain on the polished substrate surface.
Implementation Method 2
which can—if, for example, the metal ion concentration exceeds the maximum solubility of the metal-inhibitor complexes during CMP—precipitate from solution and coagulate such that a coagulated corrosion inhibitor surface residue is formed
Data Source
AI summary
A post chemical-mechanical-polishing (post-CMP) cleaning composition including:(A) polyethylene glycol (PEG) with a mass average molar mass (Mw) in the range of from 400 to 8,000 g/mol,(B) an anionic polymer selected from poly(acrylic acid) (PAA), acrylic acid-maleic acid copolymers, polyaspartic acid (PASA), polyglutamic acid (PGA), polyvinylphosphonic acid, polyvinylsulfonic acid, poly(styrenesulfonic acid), polycarboxylate ethers (PCE), PEG-phosphorous acids, and copolymers of the polymers thereof, and(C) water,where the pH of the composition is from 7.0 to 10.5.