Metal Nitride Etching via Cyclic Oxidation and Selective Oxide Removal
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Solution Overview
Problem
Existing methods for etching metal nitrides in semiconductor manufacturing face challenges in controlling the amount of material removed, leading to inefficiencies and inconsistencies in the process.
Innovation Solution
A method and system involving a sequence of oxidation and etching steps using gaseous oxidizing agents and etchants, with plasma excitation and purge cycles, to selectively etch metal oxide layers over metal nitride layers, allowing for controlled and efficient material removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used for metal nitride layers, then the etching process can be performed, but the amount of material removed cannot be precisely controlled
Solution Approach 1:
The etching process is divided into multiple sequential steps: oxidation step to form metal oxide layer, followed by etching step to remove the oxide layer. This segmentation allows independent control of each step's parameters, enabling precise control over the total material removal amount. The oxidation step converts a controlled thickness of metal nitride to metal oxide, and the subsequent etching step selectively removes this oxide layer, with each step's duration and conditions independently optimized.
Solution Approach 2:
The oxidation step is performed as a preliminary action before the etching step. By pre-oxidizing the metal nitride surface to form a metal oxide layer of controlled thickness, the subsequent etching process can precisely remove this pre-formed layer. This preliminary oxidation action enables accurate control of the etching depth, as the oxide layer thickness determines the final etch depth with high precision.
2Manufacturing precision
If selective etching of metal oxide surface layer is implemented, then etching precision is improved, but process complexity increases
Solution Approach 1:
The process exploits parameter changes in material properties through oxidation. The metal nitride layer undergoes chemical transformation to metal oxide, changing its chemical composition and reactivity. This parameter change enables selective etching because the etchant reacts differently with metal oxide versus metal nitride. By controlling oxidation conditions (time, temperature, atmosphere), the oxide layer's properties are precisely tuned to achieve the desired selective etching accuracy.
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 enables precise and efficient etching of metal nitride layers, improving control over the etching process and enhancing the accuracy and reliability of semiconductor wafer processing.
Implementation Method 1
an oxidation step that comprises providing a gaseous oxidizing agent to the reaction chamber, thereby oxidizing a surface layer of the metal nitride layer, thus forming a metal oxide surface layer
Implementation Method 2
a plasma source configured for exciting the gaseous oxidizing agent and/or the gaseous etchant, thus forming an excited gaseous oxidizing agent and/or an excited gaseous etchant
Implementation Method 3
an etching step that comprises providing a gaseous etchant to the reaction chamber, thereby selectively etching the metal oxide surface layer with respect to the unaffected metal nitride layer
Data Source
AI summary
Devices and methods for selectively etching a metal nitride layer are disclosed. The methods comprise an oxidation step and an etching step which are optionally separated by a purge, and which can be repeated in a cyclical etching process.