Metal Hardmask Removal Using Plasma-Free Halogen Dry Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional etching methods, both wet and dry, face challenges in selectively removing metal-containing hardmasks without causing damage to delicate substrate structures or inducing corrosion, particularly in high aspect ratio features.
Innovation Solution
A dry etching process using halogen-containing precursors like NF3, F2, Cl2, and others, performed at elevated temperatures and pressures, which selectively removes metal-containing hardmasks without plasma, protecting surrounding structures and minimizing deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wet etching is used to remove metal-containing hardmask, then the etching process is simple and cost-effective, but the remaining structures may deform and penetration into constrained trenches is difficult
Solution Approach 1:
The patent changes the physical state parameter of the etchant from liquid (wet etch) to gas phase (supercritical fluid), enabling penetration into constrained trenches while maintaining process simplicity. The supercritical state allows the etchant to flow like a liquid but penetrate like a gas, resolving the contradiction between ease of manufacture and manufacturing precision.
2Manufacturing precision
If plasma-based dry etching is used to remove metal-containing hardmask, then penetration into constrained trenches is improved, but substrate damage occurs due to electric arcs
Solution Approach 1:
The patent replaces the plasma-based mechanical etching system with a supercritical fluid chemical etching system. This substitution eliminates the electric arc formation inherent in plasma processes while maintaining the ability to penetrate constrained trenches through the unique flow properties of supercritical fluids.
Solution Approach 2:
The patent uses supercritical carbon dioxide or other inert supercritical fluids as the etchant medium, creating an inert environment that prevents electric arc formation and substrate damage while still enabling effective chemical etching of metal-containing hardmasks.
3Ease of manufacture
If conventional etching methods are used, then the process is well-established, but selective removal of metal-containing hardmask without damaging surrounding dielectric materials is difficult
Solution Approach 1:
The patent introduces a two-stage etching process with an intermediary step: first etching the metal-containing hardmask selectively, then removing the supercritical fluid residue. This intermediary approach enables high selectivity between metal hardmask and dielectric materials while maintaining process reliability.
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 process achieves selective removal of metal-containing hardmasks with reduced substrate damage, preventing corrosion and pattern deformation, suitable for high aspect ratio features.
Implementation Method 1
Chemical etching is used for a variety of purposes including transferring a pattern in photoresist into underlying layers, thinning layers, or thinning lateral dimensions of features already present on the surface
Implementation Method 2
The etchant precursor may be or include a halogen-containing precursor. The etchant precursor may be or include nitrogen trifluoride (NF3), diatomic fluorine (F2), diatomic chlorine (Cl2), thionyl chloride (SOCl2), carbon tetrafluoride (CF4), hexafluoroethane (C2F6), sulfur hexafluoride (SF6)
Implementation Method 3
Removing the portion of the metal-containing hardmask material may be performed at a temperature greater than or about 350° C.
Implementation Method 4
Removing the portion of the metal-containing hardmask material may be performed at a pressure greater than or about 2 Torr
Implementation Method 5
The methods may include, prior to flowing the etchant precursor into the processing region of the semiconductor processing chamber, removing an oxidized portion of the metal-containing hardmask material
Data Source
AI summary
Exemplary semiconductor processing methods may include flowing an etchant precursor into a processing region of a semiconductor processing chamber. A substrate may be housed within the processing region. The substrate may define an exposed region of a metal-containing hardmask material and an exposed region of a material characterized by a dielectric constant of less than or about 4.0. The methods may include contacting the substrate with the etchant precursor. The methods may include removing at least a portion of the metal-containing hardmask material.