Tungsten CMP Composition With Cationic Polymer for Planarity Control
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Solution Overview
Problem
Conventional CMP operations for tungsten polishing face challenges in achieving local and global planarity, leading to issues like array erosion, plug and line recessing, and tungsten etching defects, which compromise device integrity and electrical performance.
Innovation Solution
A chemical mechanical polishing composition comprising a water-based liquid carrier, abrasive particles, an iron-containing accelerator, and a cationic polymer with an amino acid monomer, such as polylysine, is used to polish tungsten layers, enhancing planarity and reducing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CMP composition is used for tungsten polishing, then polishing operation can be performed, but array erosion, plug and line recessing, and tungsten etching occur compromising planarity and device integrity
Solution Approach 1:
The patent introduces a cationic polymer as an intermediary substance in the CMP composition that mediates between the abrasive particles and the tungsten surface. This polymer adsorbs onto the tungsten surface and prevents direct harmful interaction between the abrasive/oxidizer system and the tungsten, thereby reducing etching and recessing while maintaining polishing effectiveness.
Solution Approach 2:
The patent modifies the chemical composition parameters of the CMP slurry by incorporating a cationic polymer with specific amino acid monomer content (at least 5 mol%). This parameter change alters the surface chemistry and interaction mechanisms during polishing, reducing tungsten etching rates and improving planarity control.
2Manufacturing precision
If oxide erosion is reduced to improve planarity, then device integrity is improved, but polishing rate may be affected
Solution Approach 1:
The patent optimizes the concentration and molecular weight parameters of the cationic polymer in the CMP composition to achieve a balance between oxide erosion control and polishing rate. By carefully selecting these parameters, the composition maintains effective planarity control while preserving adequate material removal speed.
Solution Approach 2:
The patent creates a composite CMP composition that combines abrasive particles, oxidizers, and cationic polymer in a synergistic formulation. This composite approach allows the oxidizer to perform its function for material removal while the polymer simultaneously protects against excessive erosion, achieving both productivity and precision.
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 improves tungsten CMP operations by inhibiting tungsten plug and line recessing, reducing array erosion, and maintaining electrical integrity by promoting effective tungsten removal while minimizing defects.
Implementation Method 1
an iron containing accelerator
Implementation Method 2
The relative motion of the substrate and pad abrades and removes a portion of the material from the surface of the substrate
Implementation Method 3
a cationic polymer having an amino acid monomer
Data Source
AI summary
A chemical mechanical polishing composition for polishing a substrate having a tungsten layer includes a water based liquid carrier, abrasive particles dispersed in the liquid carrier, an iron containing accelerator, and a cationic polymer having an amino acid monomer. A method for chemical mechanical polishing a substrate including a tungsten layer includes contacting the substrate with the above-described polishing composition, moving the polishing composition relative to the substrate, and abrading the substrate to remove a portion of the tungsten from the substrate and thereby polish the substrate.