CMP Composition for Selective Titanium Nitride and Titanium Removal
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Solution Overview
Problem
There is a need for enhanced chemical mechanical polishing compositions that exhibit improved tungsten polishing rates and selective removal rates between titanium nitride and titanium features, as existing methods lack sufficient selectivity and efficiency in planarizing semiconductor substrates.
Innovation Solution
A chemical mechanical polishing composition comprising water, an oxidizing agent, a linear polyalkylenimine polymer, a colloidal silica abrasive with a positive surface charge, a carboxylic acid, and a source of ferric ions, with a pH of 1 to 4, is used in conjunction with a polishing pad to create dynamic contact, enabling selective removal of titanium nitride and titanium features with a removal rate selectivity of ≥100.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional polishing compositions are used, then titanium nitride can be removed, but titanium is also removed at a high rate reducing selectivity
Solution Approach 1:
The polishing composition uses a highly acidic pH range (1-4) with specific buffering agents to control the chemical environment. This parameter change enables selective oxidation and removal of titanium nitride while protecting titanium, achieving ≥100:1 selectivity through controlled chemical reactions rather than mechanical abrasion alone
Solution Approach 2:
Organic buffering agents and complexing agents act as intermediaries that selectively interact with titanium nitride surfaces. These additives mediate the chemical reactions by forming temporary complexes with titanium nitride, facilitating selective removal while leaving titanium intact through controlled chemical pathways
2Productivity
If polishing pressure and speed are increased to improve planarization rate, then tungsten and titanium nitride removal rate increases, but control over selective removal becomes difficult
Solution Approach 1:
The invention replaces reliance on mechanical polishing parameters (pressure, speed) with a chemically-driven process. The highly acidic composition with specific additives performs the bulk of the removal work through chemical oxidation and dissolution, allowing mechanical parameters to be optimized for selectivity rather than just removal rate
Solution Approach 2:
By changing the chemical composition parameters (pH 1-4, specific buffering agents, complexing agents), the process achieves high planarization rates through enhanced chemical reactivity. This allows decoupling of productivity from mechanical intensity, maintaining selectivity while improving overall removal rate through chemical enhancement
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 rapid removal of tungsten and titanium nitride while significantly reducing titanium removal, thereby enhancing planarization efficiency and selectivity, particularly in semiconductor substrates with exposed titanium nitride and titanium features.
Implementation Method 1
a colloidal silica abrasive with a positive surface charge
Implementation Method 2
an oxidizing agent
Data Source
AI summary
A process for chemical mechanical polishing a substrate containing titanium nitride and titanium is provided comprising: providing a polishing composition, containing, as initial components: water; an oxidizing agent; a linear polyalkylenimine polymer; a colloidal silica abrasive with a positive surface charge; a carboxylic acid; a source of ferric ions; and, optionally pH adjusting agent; wherein the polishing composition has a pH of 1 to 4; providing a chemical mechanical polishing pad, having a polishing surface; creating dynamic contact at an interface between the polishing pad and the substrate; and dispensing the polishing composition onto the polishing surface at or near the interface between the polishing pad and the substrate; wherein at least some of the titanium nitride and at least some of the titanium is polished away with a selectivity between titanium nitride and titanium.