Platinum Thin-Film Etching with a Protective Cap Layer
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Solution Overview
Problem
Etching platinum-containing metal layers in microelectronic devices is challenging due to non-uniformity and residue issues with wet etching, and contamination and poor selectivity with dry etching methods like sputter etching.
Innovation Solution
A method involving the formation of a cap layer on the platinum-containing layer to prevent platinum oxide formation, followed by a wet etch process using a specific acid mixture that removes both the cap and platinum layers uniformly, reducing residue and overetching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet etching is used to etch platinum-containing metal, then the etching process can be performed, but the etching is non-uniform and produces platinum-containing residue in the etched areas
Solution Approach 1:
A cap layer is formed on the platinum-containing metal layer before etching to prevent oxide formation. This preliminary protective action ensures that the platinum surface remains oxide-free during subsequent processing, enabling uniform wet etching without residue formation.
Solution Approach 2:
The patent changes the chemical state of the platinum surface by preventing oxide formation through the cap layer. By maintaining platinum in its metallic state rather than oxidized state, the etching parameters are optimized for uniform removal without residue.
2Manufacturing precision
If sputter etching is used to etch platinum-containing metal, then etching can be accomplished, but redeposited platinum-containing material is formed on the microelectronic device
Solution Approach 1:
The patent replaces the mechanical sputter etching process with a chemical wet etching process. By using chemical dissolution instead of physical sputtering, redeposition of platinum material is eliminated while achieving clean, uniform etching of the platinum-containing layer.
3Manufacturing precision
If sputter etching is used to etch platinum-containing metal, then etching can be performed, but unwanted platinum containing residue is deposited on interior surfaces of the sputter etching chamber
Solution Approach 1:
The patent substitutes mechanical sputter etching with chemical wet etching using acid solutions. This chemical approach prevents the formation of redeposited residue on chamber surfaces, eliminating contamination issues while maintaining effective platinum layer removal.
4Manufacturing precision
If sputter etching is used to etch platinum-containing metal, then etching can be accomplished, but selectivity to materials in layers under the platinum-containing metal is poor
Solution Approach 1:
The patent changes the etching mechanism from physical sputtering to chemical wet etching. The chemical etchants used exhibit high selectivity for platinum-containing materials while being non-reactive toward underlying dielectric and metal layers, enabling precise pattern transfer without damaging underlying structures.
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 uniform etching of platinum-containing layers with reduced platinum residue and overetching, improving the reliability and consistency of microelectronic device fabrication.
Implementation Method 1
The cap layer and the platinum-containing layer are subsequently removed by a wet etch process
Data Source
AI summary
A microelectronic device includes a substrate a platinum-containing layer over the substrate. The platinum-containing layer includes a first segment and a second segment adjacent to the first segment, and has a first surface and a second surface opposite the first surface closer to the substrate than the first surface. A first spacing between the first segment and the second segment at the first surface is greater than a second spacing between the first segment and the second segment at the second surface. A width of the first segment along the first surface is less than twice a thickness of the first segment, and the second spacing is less than twice the thickness of the first segment.