Sacrificial Layer for Sidewall Cleanliness in Dry Etching
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Solution Overview
Problem
In dry etching processes, re-sputtered material often redeposits on patterned sidewalls, leading to the formation of features like 'rabbit or dog ears' that can cause issues during subsequent processing, as existing methods fail to effectively remove these redeposited materials.
Innovation Solution
A method involving the use of a process chamber with a plasma source and a sacrificial layer between the substrate and masking material, where the sacrificial layer is patterned to create an undercut and is removed along with the redeposited etch byproducts, preventing the formation of continuous films on sidewalls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ion driven physical etching processes are used to pattern non-volatile thin films, then etching capability is improved, but re-sputtered material redeposits on sidewalls causing defects
Solution Approach 1:
A sacrificial layer is introduced as an intermediary between the masking material and the substrate. This sacrificial layer receives the re-sputtered material during ion-driven etching, preventing it from depositing on the masking material sidewalls. The sacrificial layer is subsequently removed, taking the redeposited material with it, thus eliminating defects while maintaining effective ion-driven etching.
Solution Approach 2:
The harmful re-sputtered material is extracted from the problematic location (masking material sidewalls) by redirecting it to the sacrificial layer. The sacrificial layer acts as a temporary repository for this material, which is then removed along with the redeposited material through lift-off or etching processes, effectively extracting the harm from the final structure.
2Object-generated harmful factors
If sacrificial layer is added to prevent redeposition, then sidewall cleanliness is improved, but process complexity increases
Solution Approach 1:
The sacrificial layer is deposited and patterned in advance, before the ion-driven etching process. This preliminary action prepares the structure to capture re-sputtered material during etching, ensuring sidewall cleanliness without requiring complex real-time interventions during the etching process itself.
Solution Approach 2:
The removal of the sacrificial layer is combined with the removal of the masking material in a single lift-off or etching step. This merging of operations eliminates the need for separate removal processes, reducing overall process complexity despite the additional sacrificial layer deposition and patterning steps.
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 removes re-sputtered material, preventing the formation of 'ears' and ensuring smooth subsequent processing by using a sacrificial layer that is carefully chosen and structured to avoid redeposition issues during etching.
Implementation Method 1
generating a plasma using the plasma source; processing the substrate on the substrate support using the generated plasma
Implementation Method 2
these physical processes often result in etched material being redeposited on the patterned sidewalls of the masking material
Data Source
AI summary
The present invention provides a method for removing re-sputtered material on a substrate. A process chamber having a plasma source and a substrate support is provided along with the substrate having an upper surface and a lower surface. A masking material having a patterned sidewall is patterned onto the upper surface of the substrate along with a sacrificial layer between the upper surface of the substrate and the masking material. The lower surface of the substrate is placed onto the substrate support. A plasma is generated using the plasma source. The substrate is processed on the substrate support using the generated plasma. The sacrificial layer is removed after the processing of the substrate.