CMP Slurry for Cobalt-Copper Polishing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current chemical mechanical polishing (CMP) compositions for cobalt and copper substrates in the semiconductor industry face challenges such as low material removal rates, high corrosion of cobalt and copper, lack of selectivity control, and damage to low-k dielectric materials, leading to issues like dishing and delamination.
Innovation Solution
A CMP composition comprising colloidal or fumed inorganic particles, amino acids, corrosion inhibitors, hydrogen peroxide, and an aqueous medium, with a pH range of 6 to 9.5, which allows for adjustable selectivity between cobalt and copper, high material removal rates, and compatibility with low-k dielectric materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If acidic CMP compositions are used to reduce damage to low-k dielectric materials, then low-k dielectric compatibility is improved, but copper and cobalt dissolution increases leading to high material removal rates and dishing
Solution Approach 1:
The patent changes the pH parameter from acidic to neutral or alkaline range (pH 6-9.5), which fundamentally alters the chemical environment to reduce copper and cobalt dissolution while maintaining compatibility with low-k dielectric materials. This parameter change resolves the contradiction by creating a polishing environment that is gentle on both the metals and the dielectric layer.
Solution Approach 2:
The patent introduces amino acids as complexing agents that act as intermediaries between the CMP slurry and the metal surfaces. These amino acids form protective complexes with copper and cobalt, reducing their dissolution rates while allowing controlled material removal. The corrosion inhibitors serve as additional intermediaries that specifically target and suppress unwanted metal dissolution.
2Strength
If traditional Ta/TaN barrier/adhesion layer is used, then adhesion is improved, but resistivity increases and copper cannot be directly electroplated
Solution Approach 1:
The patent replaces the traditional Ta/TaN barrier/adhesion layer with a thinner cobalt layer that serves multiple functions. Cobalt provides both adhesion and barrier properties, reducing the total amount of material needed and lowering resistivity. The cobalt layer can be directly electroplated with copper, eliminating the need for thick Ta/TaN layers.
3Quantity of substance
If cobalt is used as adhesion/barrier layer, then resistivity decreases and adhesion improves, but dissolution in acidic solution increases leading to delamination
Solution Approach 1:
The patent changes the pH parameter to neutral or alkaline range, which dramatically reduces cobalt dissolution compared to acidic environments. This parameter change maintains the low resistivity benefit of cobalt while preventing the delamination issue that occurs in acidic CMP slurries.
Solution Approach 2:
The patent introduces corrosion inhibitors and amino acids as intermediary substances that form protective layers on the cobalt surface. These intermediaries reduce direct contact between the cobalt and the CMP slurry, preventing dissolution and delamination while allowing the cobalt to maintain its low resistivity and good adhesion properties.
4Productivity
If high material removal rate is achieved, then productivity is improved, but dishing and surface quality deteriorate
Solution Approach 1:
The patent optimizes multiple parameters including pH (6-9.5), oxidant concentration (0.01-2% H2O2), and amino acid concentration (0.1-1%) to achieve a balanced material removal rate. These parameter changes enable controlled polishing that maintains high productivity while preventing dishing and preserving surface quality through reduced aggressive chemical action.
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 achieves improved polishing performance with controllable selectivity, reduced corrosion, and high surface quality, while being storage-stable and compatible with low-k dielectric materials, thereby enhancing the reliability of semiconductor devices.
Implementation Method 1
hydrogen peroxide as oxidizing agent in a total amount of from 0.0001 to 2 wt.-% based on the total amount of the respective CMP composition
Implementation Method 2
at least one amino acid in a total amount of from 0.2 to 1 wt.-% based on the total weight of the respective CMP composition
Data Source
AI summary
A chemical mechanical polishing (CMP) composition (Q) comprising (A) Colloidal or fumed inorganic particles (A) or a mixture thereof in a total amount of from 0.0001 to 2.5 wt.-% based on the total weight of the respective CMP composition (B) at least one amino acid in a total amount of from 0.2 to 1 wt.-% based on the total weight of the respective CMP composition (C) at least one corrosion inhibitor in a total amount of from 0.001 to 0.02 wt.-% based on the total weight of the respective CMP composition (D) hydrogen peroxide as oxidizing agent in a total amount of from 0.0001 to 2 wt.-% based on the total amount of the respective CMP composition (E) aqueous medium wherein the CMP composition (Q) has a pH in the range of from 6 to 9.5.