Mask Opening Protection for High-Aspect-Ratio Etching
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Solution Overview
Problem
In semiconductor manufacturing, forming high aspect ratio patterns, such as holes for 3D NAND and DRAM, is challenging due to issues like bowing and tapering, which affect the accuracy and consistency of the pattern dimensions.
Innovation Solution
A substrate processing method involving the formation of a protective film on the mask layer with a thickness that decreases from the upper side to the lower side, allowing controlled etching to suppress shape abnormalities and maintain the desired pattern dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used to form high aspect ratio patterns, then the etching process can be completed, but shape abnormalities such as bowing and tapering occur, degrading pattern accuracy
Solution Approach 1:
The patent applies local quality by forming a protective film with non-uniform thickness on the mask layer. The protective film has greater thickness at the upper portion of the opening and gradually decreases toward the lower portion, creating different protection levels at different locations. This compensates for the non-uniform etching rates that cause bowing and tapering, thereby maintaining pattern dimension accuracy while forming high aspect ratio structures.
Solution Approach 2:
The patent changes the thickness parameter of the protective film to resolve the contradiction. By controlling the protective film thickness to decrease from the upper side to the lower side of the opening, the etching process achieves more uniform results. This parameter change allows the formation of high aspect ratio patterns while suppressing shape abnormalities like bowing and tapering.
2Length of moving object
If the aspect ratio of the pattern is increased to achieve higher integration, then vertical penetration capability is improved, but lateral etching variation increases, degrading pattern control
Solution Approach 1:
The protective film with spatially varying thickness provides localized protection during etching. The thicker upper portion prevents excessive lateral etching at the top, while the thinner lower portion allows controlled etching progression. This local quality differentiation enables the formation of deep high aspect ratio patterns while maintaining precise opening dimension control throughout the etching process.
Solution Approach 2:
The protective film is formed on the mask layer before the etching process begins. This preliminary action prepares the mask structure to resist lateral etching variations that would otherwise occur during deep etching of high aspect ratio patterns. The pre-formed protective film with graduated thickness ensures consistent opening dimensions are maintained as the etching progresses to greater depths.
Data Source
AI summary
A substrate processing method suppresses a shape abnormality of a pattern formed on a substrate. The substrate processing method executed by a substrate processing apparatus includes step a), step b), and step c). The step a) is a step of providing a substrate including an etching target film and a mask layer formed on the etching target film in which the mask layer has an opening. The step b) is a step of forming a protective film on an upper portion of an opening of the mask. The step c) is a step of etching the mask while suppressing a variation of an opening dimension of the upper portion of the opening by the protective film, and varying a dimension of a lower portion of the opening not covered by the protective film.