Post-CMP Cleaning Formulation Using Acrylamido Copolymers
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Solution Overview
Problem
Current cleaning processes in semiconductor manufacturing, particularly post-CMP cleaning of copper interconnects, are inadequate in removing inorganic particles, organic residues, and chemical residues, leading to defective chips due to residual defects on the wafer surface.
Innovation Solution
An aqueous cleaning formulation comprising copolymers of acrylamido-methyl-propane sulfonate and acrylic acid-2-acrylamido-2-methylpropane sulfonic acid, combined with quaternary ammonium hydroxides and surfactants, effectively removes residues by physical adsorption and strong affinity, improving cleaning performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional brush scrubbing cleaning process is used, then cleaning operation is simple, but residue removal effectiveness is insufficient
Solution Approach 1:
The cleaning formulation uses a composite approach by combining multiple components: copolymers of acrylamido-methyl-propane sulfonate and acrylic acid-2-acrylamido-2-methylpropane sulfonic acid as the base polymer, quaternary ammonium hydroxide as the base, and surfactants as additives. This composite formulation synergistically removes various types of residues (inorganic particles, organic residues, chemical residues) from the wafer surface, significantly improving cleaning effectiveness compared to conventional single-component cleaners.
Solution Approach 2:
The invention optimizes the chemical parameters of the cleaning formulation by controlling the molecular weight and composition ratio of the copolymer, the concentration and type of quaternary ammonium hydroxide base, and the surfactant additives. These parameter adjustments enhance the cleaning mechanism through physical adsorption and strong affinity, enabling effective removal of residues while maintaining operational simplicity.
2Reliability
If stronger cleaning chemistry is used to remove residues, then residue removal improves, but risk of redeposition or damage to substrate increases
Solution Approach 1:
The copolymer formulation acts as an intermediary substance that facilitates residue removal through physical adsorption mechanisms. The polymer chains interact with residue particles and transport them away from the substrate surface without requiring harsh chemical reactions that could cause redeposition or substrate damage. This intermediary approach enables effective cleaning while protecting the underlying copper interconnects and dielectric layers.
Solution Approach 2:
The invention replaces aggressive mechanical scrubbing with a chemical-physical mechanism based on the strong affinity and adsorption properties of the copolymer formulation. The quaternary ammonium hydroxide and surfactant components enhance this mechanism by reducing surface tension and improving wetting, allowing gentle yet effective residue removal without the mechanical stress that could cause substrate damage or redeposition.
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 formulation significantly reduces residue defects on semiconductor substrates, enhancing the quality of post-CMP cleaning and other applications like photo-resist ash residue removal and back-end packaging by effectively lifting off residues without redeposition.
Implementation Method 1
effectively removes residues by physical adsorption and strong affinity
Data Source
AI summary
The present invention is a method of cleaning to removal residue in semiconductor manufacturing processing, comprising contacting a surface to be cleaned with an aqueous formulation having a polymer selected from the group consisting of acrylamido-methyl-propane sulfonate polymers, acrylic acid-2-acrylamido-2-methylpropane sulfonic acid copolymer and mixtures thereof and a quaternary ammonium hydroxide having greater than 4 carbon atoms or, where the formulation does not contain an acetylinic surfactant, choline hydroxide. The present invention is also a post-CMP cleaning formulation having the components set forth in the method above.