Chalcogenide Layer Etching via Protective Mask
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Solution Overview
Problem
Conventional methods for etching chalcogenide layers in semiconductor devices often result in hardened photoresist elements that are difficult to remove and undercut chalcogenide elements with uncontrolled sizes, affecting the electrical properties of phase change memory devices.
Innovation Solution
A method involving the deposition of a protective layer between the chalcogenide layer and the photoresist layer, using a gas mixture like C4F8, CO, and O2 for etching the photoresist and protective layers, and subsequently etching the chalcogenide layer through openings with Cl2, to achieve a good profile with straight inside walls and avoid chemical reactions that complicate the removal of hardened photoresist elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used on chalcogenide layers, then photoresist elements are etched, but hardened photoresist elements form that are difficult to remove
Solution Approach 1:
The patent segments the etching process into two distinct steps: first etching the photoresist and protective layer together using C4F8/CO/O2 gas mixture, then removing photoresist and etching the chalcogenide layer separately using Cl2 gas. This segmentation prevents the formation of hardened photoresist elements that are difficult to remove, while maintaining precise etching control.
Solution Approach 2:
The patent introduces a protective layer as an intermediary between the photoresist and the chalcogenide layer. This protective layer mediates the etching process by providing a controlled interface that prevents direct harmful interactions between the photoresist etching chemicals and the chalcogenide layer, thereby preventing hardened photoresist formation while enabling precise pattern transfer.
2Productivity
If photoresist and protective layer are etched together, then openings are formed to the chalcogenide layer, but chemical reactions complicate photoresist element removal
Solution Approach 1:
The patent segments the etching process into two distinct steps: first etching the photoresist and protective layer together using C4F8/CO/O2 gas mixture, then removing photoresist and etching the chalcogenide layer separately using Cl2 gas. This segmentation prevents the formation of hardened photoresist elements that are difficult to remove, while maintaining precise etching control.
Solution Approach 2:
The patent introduces a protective layer as an intermediary between the photoresist and the chalcogenide layer. This protective layer mediates the etching process by providing a controlled interface that prevents direct harmful interactions between the photoresist etching chemicals and the chalcogenide layer, thereby preventing hardened photoresist formation while enabling precise pattern transfer.
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 prevents the formation of hardened photoresist elements and achieves chalcogenide elements with controlled sizes and straight walls, improving the electrical properties and manufacturing efficiency of phase change memory devices.
Implementation Method 1
The patterned photoresist layer and protective layer etching step is carried out using a gas mixture comprising C4F8, CO and O2
Implementation Method 2
The chalcogenide layer etching step may be carried out using Cl2
Data Source
AI summary
A protective layer is deposited on a chalcogenide layer and a patterned photoresist layer is formed on the protective layer. The patterned photoresist layer and the protective layer are etched to form openings therethrough to the chalcogenide layer to create etched photoresist and etched protective layers. The etched photoresist layer is removed leaving at least a portion of the etched protective layer. The chalcogenide layer is etched through the openings in the etched protective layer.