Metal Removal via Alternating Oxidizing Reducing Environments
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Solution Overview
Problem
The existing methods for removing metal from substrates during integrated circuit fabrication are often incomplete, leaving behind trace contamination due to variability in manufacturing conditions and the difficulty in removing metal oxides like ruthenium dioxide, which hinders the production of high-quality integrated circuit devices.
Innovation Solution
A method involving alternating oxidizing and reducing environments, using both oxidizing and reducing agents, to oxidize unwanted metals and then reduce them back to their elemental form, facilitating the removal of metal oxides and improving the ashing of organic residuals, thereby ensuring complete removal of metals like ruthenium, osmium, and iridium from substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single removal process is performed for a limited time to mitigate damage to surrounding structures, then damage to surrounding materials is reduced, but incomplete removal of metal leaves trace contamination on the underlying surface
Solution Approach 1:
The removal process is divided into multiple sequential stages: a first removal process that removes the majority of metal, followed by a second removal process that eliminates remaining trace contamination. This segmentation allows each stage to be optimized independently - the first stage removes bulk material efficiently, while the second stage specifically targets residual contamination without causing damage to surrounding structures.
Solution Approach 2:
The first removal process is performed as a preliminary action to remove the majority of metal before the second removal process. By预先 removing the bulk metal, the subsequent second removal process only needs to handle trace contamination, reducing the time and intensity needed and thereby minimizing damage to surrounding structures while ensuring complete removal.
2Manufacturing precision
If the removal process is extended to ensure complete metal removal, then trace contamination is eliminated, but unnecessary exposure time increases damage to surrounding materials
Solution Approach 1:
The removal process is segmented into two distinct stages with different objectives and parameters. The first stage removes the majority of metal with longer exposure time, while the second stage eliminates trace contamination with shorter exposure time. This segmentation achieves complete removal (high manufacturing precision) without requiring continuously extended exposure time, as each stage is optimized for its specific purpose.
Solution Approach 2:
The first removal process applies excessive action by removing more metal than strictly necessary, including some margin beyond the target pattern. This ensures that the second removal process only needs to handle trace contamination rather than bulk material, significantly reducing the time needed in the second stage and overall process time while guaranteeing complete removal.
3Reliability
If strong removal agents are used to ensure complete metal removal, then removal effectiveness is improved, but damage to surrounding structures increases
Solution Approach 1:
The removal process is segmented into two stages with progressively milder agents or conditions. The first stage uses a stronger removal agent to remove bulk metal, while the second stage uses a milder agent or reduced intensity to eliminate trace contamination. This segmentation allows strong action when needed (first stage) while protecting surrounding structures during the final cleanup (second stage), achieving complete removal without excessive damage.
Solution Approach 2:
The stronger removal action is applied preliminarily in the first stage to remove the majority of metal. By预先 applying the stronger agent, the second stage can use milder conditions, reducing overall damage to surrounding structures while ensuring complete removal. The preliminary strong action prevents the need for prolonged mild action that would also cause damage.
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 reduces the amount of unwanted metals to below detectable levels, ensuring the quality of integrated circuit devices by repeatedly cycling through oxidizing and reducing stages, addressing the issue of incomplete removal and residual contamination.
Implementation Method 1
exposing the substrate to an oxidizing environment to oxidize unwanted metals
Implementation Method 2
exposing the substrate to a reducing environment to reduce the metal oxides back to their elemental form
Data Source
AI summary
Methods of removing metal from a portion of a substrate include exposing the substrate to a reducing environment comprising at least one reducing agent and at least one oxidizing agent, determining whether metal remaining on the portion of the substrate is less than or equal to a particular level, and exposing the substrate to an oxidizing environment comprising at least one oxidizing agent and at least one reducing agent if the metal remaining on the portion of the substrate is deemed to be greater than the particular level.