Atomic Layer Etching of Chemically Resistant Films via Cyclic Plasma
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Solution Overview
Problem
Current atomic layer etching methods often fail to remove layers precisely without damaging surrounding materials or leaving significant residue, particularly when dealing with films like Ti-containing, Ta-containing, and W-containing films, which are chemically resistant and difficult to remove using traditional liquid phase solvents.
Innovation Solution
A method involving pulsing a plasma containing a halide-containing compound and a volatile organic compound in a cyclic process, where the halide-containing compound is introduced into a chamber with the substrate, followed by ignition of plasma and purging, effectively removing one atomic layer of the film without damaging the substrate or leaving residue, using compounds like Cl2, HCl, or BCl3, and volatile organic compounds such as alcohols or amines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional liquid phase solvents are used to remove films, then the etching process is simple, but the films are not removed precisely and significant residue is left on the substrate
Solution Approach 1:
The invention transitions from liquid phase solvent-based etching to plasma phase etching. The plasma state enables precise atomic layer removal through controlled chemical reactions, preventing residue formation that plagues liquid phase methods. The plasma process transforms the etching mechanism from dissolution to controlled vapor-phase chemical reactions followed by thermal desorption.
Solution Approach 2:
The invention changes the physical and chemical parameters of the etching process by using plasma instead of liquid solvents. This includes controlling plasma power, gas composition, temperature, and pressure to achieve self-limiting atomic layer etching with high precision and no residue, fundamentally altering the etching mechanism from liquid-phase dissolution to plasma-phase chemical reactions.
2Manufacturing precision
If plasma etching is used to remove chemically resistant films, then etching precision is improved, but surrounding materials may be damaged
Solution Approach 1:
The invention segments the plasma etching process into distinct cyclic stages: a first plasma phase for controlled film removal, followed by a second plasma phase for cleaning and a third plasma phase for stabilization. This segmentation allows precise control over etching depth and prevents damage to surrounding materials by limiting each phase's exposure time and adjusting parameters independently.
Solution Approach 2:
The invention employs periodic cyclic plasma treatment with alternating phases of different power levels and gas compositions. The periodic cycling between etching and cleaning phases enables precise atomic layer removal while continuously protecting surrounding materials from excessive plasma exposure, achieving high precision without damage.
3Manufacturing precision
If cyclic plasma etching is used to achieve precise atomic layer removal, then manufacturing precision is improved, but process complexity increases
Solution Approach 1:
The invention uses a single plasma reactor system that can operate in multiple modes (different plasma phases with varying power and gas composition) to achieve etching, cleaning, and stabilization functions. This multi-functionality within one device avoids the need for multiple separate processing tools, reducing overall system complexity while maintaining atomic layer precision.
Solution Approach 2:
The invention implements continuous cyclic plasma processing where each cycle builds upon the previous one, with the second and third plasma phases preparing the surface for the next etching cycle. This continuous action eliminates idle time between cycles and maintains precise control throughout the multi-cycle process, managing complexity through streamlined continuous operation rather than discrete interrupted steps.
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
This process allows for precise and selective etching of sacrificial mask materials and metal layers, preventing damage to the substrate and enabling efficient removal of chemically resistant films, such as TiN, Ta, and W, with high selectivity and minimal residue, improving the etching process in semiconductor manufacturing.
Implementation Method 1
pulsing a plasma containing a halide-containing compound and a volatile organic compound
Implementation Method 2
A vapor of a halide-containing compound is introduced into a chamber containing the substrate having the film disposed thereon. Plasma is ignited in the chamber.
Implementation Method 3
The vapor of a volatile organic compound is introduced into the chamber
Implementation Method 4
A vapor of a halide-containing compound is introduced into a chamber
Implementation Method 5
Plasma is ignited in the chamber
Implementation Method 6
U.S. Pat. No. 4,756,794 discloses an atomic layer etching method to remove diamond by NO2 followed by ion bombardment
Data Source
AI summary
Atomic layer or cyclic plasma etching chemistries and processes to etch films are disclosed. Films include Si, Ti, Ta, W, Al, Pd, Ir, Co, Fe, B, Cu, Ni, Pt, Ru, Mn, Mg, Cr, Au, alloys thereof, oxides thereof, nitrides thereof, and combinations thereof.