Ion Implantation for Selective Etching of Microelectronic Layers
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Solution Overview
Problem
Current etching techniques, particularly plasma etching, face challenges in achieving high selectivity and precise control of critical dimensions for microelectronic patterns, leading to defects and reduced yield due to lateral etching and damage to non-etched layers, especially at the 22 nm technological node and beyond.
Innovation Solution
A method involving the modification of the layer to be etched using light ion implantation from a plasma comprising helium and hydrogen, followed by selective removal of the modified film, which enhances etching selectivity and anisotropy, allowing for improved precision and control of engraved thickness without significant impact on reactor walls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If plasma etching is used to achieve anisotropic etching profiles, then vertical etching precision is improved, but selectivity between different materials deteriorates
Solution Approach 1:
The patent applies preliminary action by performing ion implantation into the layer to be etched before the actual etching process. This pre-modifies the material properties of the target layer, making it more susceptible to selective removal while preserving the mask and underlying layers. The implantation creates a modified film that has enhanced etchability compared to the original material, thereby achieving high selectivity without compromising vertical precision
Solution Approach 2:
The patent applies local quality by modifying only the specific layer that needs to be etched through ion implantation, while leaving other layers and the mask unchanged. This localized modification ensures that the etching process selectively removes only the implanted layer with high precision, maintaining both vertical etching accuracy and material selectivity by creating a unique property in the target layer that distinguishes it from surrounding materials
2Productivity
If pattern dimensions are reduced to increase circuit density, then productivity is improved, but manufacturing precision deteriorates due to lateral etching
Solution Approach 1:
The patent applies parameter changes by modifying the physical and chemical properties of the layer to be etched through ion implantation. This changes the etchability parameter of the target layer, enabling highly selective removal with minimal lateral attack. By altering the material properties rather than changing the etching process itself, the method achieves precise critical dimension control even at reduced pattern dimensions, thereby maintaining manufacturing precision while supporting increased circuit density
3Speed
If conventional plasma etching is used, then etching speed is improved, but harmful factors increase due to damage to non-etched layers
Solution Approach 1:
The patent applies preliminary anti-action by pre-implanting ions into the layer to be etched, which creates a modified film that is selectively vulnerable to removal. This preliminary modification protects the intended structure by creating a clear distinction between the etchable layer and protected layers, allowing fast etching speeds without damaging non-etched areas. The implanted ions create a chemical or structural change that enables rapid selective removal while leaving surrounding materials intact, thereby reducing harmful effects
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 significantly increases etching selectivity and precision, reducing defects and improving the control of critical dimensions, while minimizing damage to non-etched layers and maintaining reactor integrity.
Implementation Method 1
modification of the layer to be etched by implantation in the layer to be etched of species, chosen from among light ions, these light ions being taken from among helium and hydrogen
Implementation Method 2
removal of the modified film comprising a selective etching of the film with respect to at least one layer underlying the film
Data Source
Figure 1a~1c
Figure 2a~2d
Figure 3
AI summary
The invention relates to a microelectronic method for etching a layer to be etched, comprising the following steps: - modifying the layer to be etched from the surface of the layer to be etched and over a depth corresponding to at least a portion of the thickness of the layer to be etched so as to form a film, the modification comprising implanting light ions in the layer to be etched; - removing the film comprising a selective etching of the film relative to at least one layer underlying the film.