Metal Halide Ligand Etching for MRAM Profile Control
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Solution Overview
Problem
Current patterning technologies for semiconductor devices, particularly magnetic random access memory (MRAM), face challenges such as sidewall re-deposition and corrosion during etching, leading to tapered profiles and device failure, especially for small critical dimension and tight pitch features, due to limitations in ion beam etching and reactive ion etching.
Innovation Solution
A method involving exposure of metal-containing materials to halogen-containing fluids or plasmas to form metal halides, followed by exposure to ligand-containing fluids or plasmas to create metal halide ligand complexes, which are then vaporized, facilitating a controlled and conformal etching process through atomic layer etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ion beam etching or reactive ion etching is used to etch MRAM stacks, then etching capability is achieved, but sidewall re-deposition occurs causing tapered profiles and device failure
Solution Approach 1:
The etching process is divided into multiple sequential steps with different chemistries and parameters. The first step uses a specific etch recipe to remove material, while subsequent steps address sidewall re-deposition and profile correction. This segmentation allows each step to be optimized for its specific function, resolving the contradiction between achieving etching capability and maintaining profile control.
Solution Approach 2:
The patent employs periodic alternation between etching steps and cleaning/stabilization steps. By periodically switching between aggressive etching conditions and gentler cleaning conditions, the process achieves both effective material removal and prevention of sidewall re-deposition, thereby maintaining vertical profiles throughout the etching sequence.
2Productivity
If conventional etching methods are used for small critical dimension features of sub-100 nm, then etching is performed, but ion incidence shadowed by mask prevents effective etch and trim
Solution Approach 1:
The patent dynamically adjusts etching parameters including ion beam angle, energy, and chemistry composition throughout the process. By making the etching conditions dynamic rather than static, the process can adapt to changing feature dimensions and mask shadowing effects, enabling effective etching of sub-100 nm features while maintaining critical dimension control.
Solution Approach 2:
Multiple etching parameters are changed systematically across different process steps: gas flow rates, pressure, ion energy, and temperature are adjusted to optimize etching performance at each stage. These parameter changes enable the process to overcome mask shadowing effects and achieve precise critical dimension control for small features.
3Productivity
If chlorine-containing chemistry is used to etch metal, then etching is achieved, but non-volatile byproducts re-deposit onto sidewalls causing defects
Solution Approach 1:
The patent introduces intermediate process steps with different chemistries that act as mediators between the primary etching step and the final cleaning step. These intermediate steps convert non-volatile etch byproducts into more volatile species or remove them through selective chemical reactions, preventing their re-deposition on sidewalls while maintaining effective metal etching capability.
Solution Approach 2:
The patent employs oxidizing chemistries in subsequent process steps to convert metallic etch byproducts into oxidized forms that are either more volatile or can be more effectively removed. This accelerated oxidation prevents non-volatile compound re-deposition while maintaining the effectiveness of the primary chlorine-containing etching step.
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 approach reduces sidewall re-deposition, minimizes chemical damage, and enables effective etching of MRAM stacks with improved profile control and reduced aspect ratio dependence, enhancing the scalability and reliability of semiconductor device fabrication.
Implementation Method 1
The metal containing material is exposed to a halogen containing fluid or plasma to convert at least some of the metal containing material into a metal halide material
Implementation Method 2
The metal halide material is exposed to a ligand containing fluid or plasma, wherein at least some of the metal halide material is formed into a metal halide ligand complex
Implementation Method 3
At least some of the metal halide ligand complex is vaporized
Implementation Method 4
The metal containing material is exposed to a halogen containing fluid or plasma
Data Source
AI summary
A method for etching a metal containing material is provided. The metal containing material is exposed to a halogen containing fluid or plasma to convert at least some of the metal containing material into a metal halide material. The metal halide material is exposed to a ligand containing fluid or plasma, wherein at least some of the metal halide material is formed into a metal halide ligand complex. At least some of the metal halide ligand complex is vaporized.