Atomic Layer Etching of Cobalt Thin Films With Amine Support Gas
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Solution Overview
Problem
Current semiconductor manufacturing methods lack precise control over dry etching processes for metal thin films, particularly for cobalt, which is essential for achieving high integration levels and preventing defects in semiconductor devices.
Innovation Solution
An atomic layer etching method involving the formation of a metal layer on a substrate, followed by etching cycles using a halogen gas and an amine-based etching support gas, such as pentamethyldiethylenetriamine, to selectively etch the metal layer while minimizing damage and maintaining low temperature processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet etching methods are used to remove cobalt thin film, then etching can be performed, but precise control of etching rate and dimensional accuracy cannot be achieved
Solution Approach 1:
The etching process is divided into multiple sequential steps: (1) supplying halogen gas to form metal halide, (2) supplying amine-based etching support gas to form volatile complex, (3) purging reaction byproducts. This segmentation enables precise control at each stage, achieving atomic layer etching precision of 1-3 nm per cycle.
Solution Approach 2:
The amine-based etching support gas acts as an intermediary that forms a volatile complex with the metal halide intermediate. This intermediary step enables controlled removal of the metal layer with precise dimensional control, transforming the intermediate compound into removable form through chemical coordination.
2Manufacturing precision
If conventional dry etching is used, then etching can be performed, but accurate control of etch rate at atomic layer precision is not achieved
Solution Approach 1:
The etching process uses periodic cyclic action with repeated cycles of halogen gas supply followed by amine-based etching support gas supply. Each cycle removes a controlled atomic layer thickness, enabling cumulative precise etching while maintaining high productivity through automated cyclic operation.
Solution Approach 2:
The process controls etching parameters including gas flow rates, pressure, temperature, and cycle frequency to achieve saturated etch rate. By optimizing these parameters, the process achieves both atomic layer precision (1-3 nm/cycle) and high productivity through saturated etching conditions.
3Productivity
If high plasma power is used to increase etching speed, then productivity improves, but plasma-induced damage to the substrate increases
Solution Approach 1:
The process replaces high-power physical plasma etching with a chemical-based atomic layer etching mechanism. By using sequential chemical reactions (halogenation followed by complex formation with amine), the process achieves high etching speed without the mechanical damage caused by high-energy plasma ions, thereby reducing substrate damage while maintaining productivity.
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 method enables precise control over the etching process, achieving a saturated etch rate with reduced etching support gas consumption and minimizing plasma-induced damage, allowing for accurate dimensional accuracy and improved semiconductor device reliability.
Implementation Method 1
supplying an active gas including a halogen gas onto the metal layer
Implementation Method 2
supplying an amine based etching support gas after supplying the active gas
Implementation Method 3
supplying an active gas including a halogen gas onto the metal layer
Data Source
AI summary
An atomic layer etching method capable of precisely etching a metal thin film at units of atomic layer from a substrate including the metal thin film, includes forming a metal layer on a substrate, and etching at least a portion of the metal layer. The etching at least a portion of the metal layer includes at least one etching cycle. The at least one etching cycle includes supplying an active gas onto the metal layer, and supplying an etching support gas after supplying the active gas. The etching support gas is expressed by the following general formulawherein each of R1, R2, R3, R4 and R5 independently includes hydrogen or a C1-C4 alkyl group, and N is nitrogen.