Polymer Surface Treatment for CMP Residue Removal on SiN Wafers
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Solution Overview
Problem
Current cleaning compositions are inadequate for effectively removing residues from semiconductor substrates containing silicon nitride and combinations of silicon oxide and polysilicon after chemical mechanical polishing, leading to potential electrical property degradation and device reliability issues.
Innovation Solution
A surface treatment composition comprising a nitrogen-free nonionic polymer, a nitrogen-containing nonionic polymer, and an anionic polymer, with specific molecular weight ratios and pH levels, which effectively adsorbs and desorbs residues from the substrate surfaces, preventing re-adhesion and ensuring thorough removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional cleaning compositions are used, then general cleaning is achieved, but residues cannot be sufficiently removed from silicon nitride and silicon oxide/polysilicon surfaces
Solution Approach 1:
The invention changes the chemical parameters of the cleaning composition by specifying precise pH ranges (2.0-6.0 for first cleaning, 7.0-11.0 for second cleaning) and molecular weight ratios of polymers. These parameter changes enable effective removal of residues from silicon nitride and silicon oxide/polysilicon surfaces without causing re-adhesion, thereby simultaneously improving surface cleanliness and device reliability
Solution Approach 2:
The invention uses composite cleaning compositions containing multiple components with specific functions: nitrogen-free nonionic polymers (weight-average molecular weight 1,000-100,000), nitrogen-containing nonionic polymers (weight-average molecular weight 1,000-1,000,000), and anionic polymers (weight-average molecular weight 1,000-1,000,000). The composite nature of these compositions allows synergistic removal of various residues while preventing re-adhesion through electrostatic repulsion and hydrophilic film formation
2Productivity
If cleaning compositions with inappropriate pH or polymer ratios are used, then cleaning efficiency is reduced, but re-adhesion of residues occurs
Solution Approach 1:
The invention optimizes parameters by defining specific pH ranges for different cleaning stages (acidic pH 2.0-6.0 for initial cleaning, basic pH 7.0-11.0 for final cleaning) and precise molecular weight ratios of polymers. These parameter optimizations ensure high cleaning efficiency while maintaining composition stability that prevents residue re-adhesion through controlled electrostatic repulsion and hydrophilic film formation
Solution Approach 2:
The invention employs periodic cleaning action with two distinct cleaning compositions applied in sequence: first an acidic cleaning composition (pH 2.0-6.0) to remove initial residues, then a basic cleaning composition (pH 7.0-11.0) to remove remaining residues and prevent re-adhesion. This periodic alternation of cleaning conditions maximizes cleaning efficiency while ensuring stable residue-free surfaces
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 residues from silicon nitride and silicon oxide/polysilicon surfaces, enhancing semiconductor substrate cleanliness and device reliability by forming a hydrophilic film and promoting electrostatic repulsion, thereby reducing defects.
Implementation Method 1
the composition efficiently removes residues from silicon nitride and silicon oxide/polysilicon surfaces, enhancing semiconductor substrate cleanliness
Implementation Method 2
promoting electrostatic repulsion, thereby reducing defects
Implementation Method 3
forming a hydrophilic film and promoting electrostatic repulsion
Data Source
AI summary
Means capable of sufficiently removing residues remaining on a surface of a polished object containing silicon nitride and at least one selected from the group consisting of silicon oxide and polysilicon is provided. A composition for surface treatment, comprising: a nitrogen-free nonionic polymer, a nitrogen-containing nonionic polymer, and an anionic polymer, wherein the nitrogen-free nonionic polymer has a weight-average molecular weight of less than 100,000, the ratio of a weight-average molecular weight of the nitrogen-containing nonionic polymer to the weight-average molecular weight of the nitrogen-free nonionic polymer (nitrogen-containing nonionic polymer/nitrogen-free nonionic polymer) is 0.1 or more and 10 or less, and the composition for surface treatment has a pH of less than 7.0.