Air Gap Sealing Structure for Overhang Recess Substrates
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Solution Overview
Problem
Existing methods for forming air gaps in substrates face challenges in efficiently creating a sealing structure that effectively seals recesses while maintaining low relative dielectric constant and preventing current leakage between adjacent elements.
Innovation Solution
A method involving the formation of a sacrificial layer and a sealing layer with different etching resistances, followed by plasma-etching to create a sealing portion that seals the recess, thereby forming an air gap structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sealing layer with high etching resistance is formed to seal the recess, then current leakage is prevented, but the formation of a stable sealing structure becomes difficult when the recess has an overhang
Solution Approach 1:
The patent divides the sealing structure into two distinct layers: a sacrificial layer (first layer) and a sealing layer (second layer). The sacrificial layer is formed in the recess including the overhang region, while the sealing layer is formed on top of the sacrificial layer. This segmentation allows the sacrificial layer to provide structural support during formation, enabling the sealing layer to be formed with high etching resistance without compromising stability. After etching, the sacrificial layer is removed, leaving the sealing layer as a stable structure that prevents current leakage.
Solution Approach 2:
The sacrificial layer is formed in advance before the sealing layer. This preliminary action provides a stable foundation and overhang support structure that enables the subsequent sealing layer to be formed with high etching resistance. The sacrificial layer acts as a temporary support structure that is removed after the sealing layer is properly formed and etched, leaving a stable sealing structure.
2Productivity
If the recess has an overhang structure, then the air gap formation is enabled, but the sealing layer formation becomes challenging due to the overhang geometry
Solution Approach 1:
The sacrificial layer acts as an intermediary material that facilitates the formation of the sealing layer over the overhang structure. It provides a temporary support and formation surface that enables the sealing layer to be deposited conformally over the overhang. After the sealing layer is formed, the sacrificial layer is removed through etching, leaving the desired air gap structure with the sealing layer in place.
Solution Approach 2:
The sacrificial layer is designed to be self-removed through selective etching. The etching process automatically removes the sacrificial layer while leaving the sealing layer intact due to the difference in etching resistance. This self-service mechanism eliminates the need for additional complex removal steps and enables automatic air gap formation.
3Device complexity
If a single-layer sealing structure is used, then the process is simple, but the sealing effectiveness and current leakage prevention are insufficient
Solution Approach 1:
The sealing structure is segmented into two functional layers: the sacrificial layer that provides structural support and enables overhang formation, and the sealing layer that provides high etching resistance and current leakage prevention. This segmentation allows each layer to be optimized for its specific function, improving overall sealing effectiveness while maintaining process simplicity.
Solution Approach 2:
The patent utilizes parameter changes in etching resistance between the two layers. The sacrificial layer has lower etching resistance and is selectively removed, while the sealing layer has higher etching resistance and remains to provide sealing. This parameter differentiation enables the dual-layer structure to achieve superior sealing effectiveness with a relatively simple process.
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
The method achieves a lower relative dielectric constant in recesses and suppresses current leakage by forming a stable air gap structure with a sealing portion that effectively seals the recess.
Implementation Method 1
plasma-etching the substrate on which the sacrificial layer and the sealing layer are formed to form a sealing portion
Data Source
AI summary
According to one embodiment of the present disclosure, there is provided a method of processing a substrate. The method includes preparing a substrate including a recess which has an overhang, forming a sacrificial layer on the substrate, forming a sealing layer on the sacrificial layer, the sealing layer including a higher etching resistance than the sacrificial layer; and plasma-etching the substrate on which the sacrificial layer and the sealing layer are formed to form a sealing portion that seals an upper portion of the recess, thereby forming an air gap structure.