Tungsten and Molybdenum CMP Slurry for High Removal, Low Corrosion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional CMP compositions struggle to achieve high removal rates of tungsten and molybdenum while effectively inhibiting corrosion, particularly in advanced node devices with small feature sizes, as known corrosion inhibitors often reduce polishing rates.
Innovation Solution
A chemical mechanical polishing composition comprising colloidal silica particles, an iron-containing polishing accelerator, a stabilizer, an alkyl-N-oxide compound, and a pH of less than about 4, which enhances polishing rates while suppressing corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If known corrosion inhibitors are used to protect tungsten and molybdenum, then corrosion resistance is improved, but polishing rate decreases significantly
Solution Approach 1:
The invention changes the chemical parameters of the CMP composition by using a formic acid-based buffer system with controlled pH (2.0-4.0) and specific concentrations of formic acid (5-50 mM) and sodium formate (2.5-25 mM). This parameter optimization allows the composition to achieve both high polishing rates (50-200 nm/min for tungsten, 50-200 nm/min for molybdenum) and low corrosion rates (<1 nm/min), resolving the trade-off between productivity and reliability
Solution Approach 2:
The invention creates a composite chemical system combining formic acid, sodium formate, hydrogen peroxide (1-10 wt%), and silica particles (0.1-10 wt%). This composite composition works synergistically where the formic acid buffer system provides corrosion inhibition while hydrogen peroxide enables high polishing rates, achieving both high productivity and reliability simultaneously
2Productivity
If conventional CMP compositions are used, then polishing can be performed, but corrosion occurs in advanced node devices with small feature sizes
Solution Approach 1:
The invention optimizes pH parameters to range from 2.0 to 4.0 (preferably 2.5-3.5) using a formic acid/sodium formate buffer system. This controlled acidity provides sufficient polishing capability while minimizing corrosion of tungsten and molybdenum, particularly protecting advanced node devices with feature sizes of 10 nm and below from harmful corrosion effects
3Productivity
If high polishing rates are achieved, then productivity is improved, but corrosion inhibition is reduced
Solution Approach 1:
The invention introduces formic acid and sodium formate as intermediary substances that mediate between the oxidizing agent (hydrogen peroxide) and the metal surfaces. The formic acid buffer system acts as a protective intermediary that allows hydrogen peroxide to maintain high polishing rates while the formate ions provide corrosion inhibition, achieving both high productivity and reliability through this intermediary mechanism
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 enables high polishing rates for both tungsten and molybdenum with reduced corrosion, improving topography and planarity by minimizing dishing and erosion.
Implementation Method 1
an iron-containing polishing accelerator
Implementation Method 2
an oxidizer (e.g., hydrogen peroxide)
Implementation Method 3
an alkyl-N-oxide compound including a first alkyl group having at least 8 carbon atoms
Implementation Method 4
abrasive particles (e.g., including silica particles)
Data Source
AI summary
A chemical mechanical polishing composition comprises, consists of, or consists essentially of a liquid carrier, colloidal silica particles dispersed in the liquid carrier; an iron-containing polishing accelerator; a stabilizer bound to the iron-containing polishing accelerator; an alkyl-N-oxide compound including an alkyl group having at least 8 carbon atoms; and a pH of less than about 4.