STTM Sidewall Redeposition Removal via Volatile Oxide Formation
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Solution Overview
Problem
The manufacturing of spin transfer torque memory (STTM) devices faces challenges due to the redeposition of conductive materials during etching processes, leading to electrical shorts, as these materials do not form volatile compounds under typical removal conditions, such as ion milling at room temperature.
Innovation Solution
Forming conductive layers from materials like ruthenium, which form volatile oxides in oxygen-containing atmospheres, allowing for the removal of redeposited layers without causing further electrical connectivity issues, thereby preventing shorts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching processes are used to remove redeposited layers, then manufacturing precision is maintained, but electrical shorts occur due to redeposition of conductive materials
Solution Approach 1:
The patent changes the chemical parameters of the etching process by introducing oxygen-containing atmospheres and reactive ions that selectively oxidize and remove redeposited conductive materials without affecting the underlying dielectric layer, thus preventing electrical shorts while maintaining etching precision
Solution Approach 2:
The patent introduces oxygen and oxygen-containing compounds as intermediary substances that facilitate the selective removal of redeposited conductive layers. These intermediaries react with the conductive materials to form volatile oxides that can be easily removed without causing electrical shorts
2Manufacturing precision
If ion milling is performed at room temperature, then manufacturing precision is maintained, but conductive materials cannot be removed as they do not form volatile compounds
Solution Approach 1:
The patent changes the chemical environment parameters by introducing oxygen-containing atmospheres during room temperature ion milling, enabling conductive materials to form volatile oxides and be removed without requiring temperature increases that would compromise manufacturing precision
Solution Approach 2:
The patent replaces purely mechanical sputtering removal with a chemically-assisted removal process where reactive oxygen species chemically modify the conductive materials into volatile compounds, enabling easier removal without compromising the precision of the ion milling process
3Device complexity
If conductive materials are redeposited on sidewalls, then device complexity is reduced, but electrical shorts are caused disrupting functionality
Solution Approach 1:
The patent converts the harmful effect of conductive material redeposition into a beneficial process by using the same redeposited materials as the source of oxygen-containing species that selectively remove other conductive contaminants, thus eliminating electrical shorts while maintaining process simplicity
Solution Approach 2:
The patent implements a self-cleaning mechanism where the redeposited conductive layer on sidewalls serves as the etchant source for removing conductive materials from other surfaces, eliminating the need for additional cleaning process steps while maintaining electrical isolation
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 effectively disrupts the electrical continuity of redeposited layers on STTM device sidewalls, preventing shorts and enabling the mass production of STTM elements while maintaining the integrity of the dielectric layer.
Implementation Method 1
the conductive layer includes a conductive material that forms a volatile species when exposed to a reactant gas
Implementation Method 2
subjecting the STTM precursor to ion milling in an atmosphere containing a reactant gas
Data Source
AI summary
Technologies for manufacturing spin transfer torque memory (STTM) elements are disclosed. In some embodiments, the technologies include methods for removing a re-deposited layer and/or interrupting the electrical continuity of a re-deposited layer that may form on one or more sidewalls of an STTM element during its formation. Devices and systems including such STTM elements are also described.