Substrate Processing Film Thickness Control for High Aspect Ratio Etching
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Solution Overview
Problem
The increasing aspect ratio of patterns in semiconductor manufacturing, particularly in 3D NAND structures, poses challenges in achieving high accuracy and uniformity in etching and film formation, leading to shape abnormalities such as bowing and tapering, which existing methods struggle to correct effectively.
Innovation Solution
A substrate processing method involving the formation of a film with varying thickness along the film thickness direction on the side wall of high aspect ratio openings, using techniques like sub-conformal ALD, followed by trimming to correct shape abnormalities, allowing for precise control of opening dimensions and preventing the closure of openings during etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If etching and film formation are repeatedly performed to suppress lateral etching, then etching accuracy is improved, but manufacturing complexity increases
Solution Approach 1:
A film is formed in advance on the side wall of the opening before the etching process. This preliminary film formation creates a protective layer that prevents lateral etching, eliminating the need for repeated etching and film formation cycles. The film is formed once, then the etching process can proceed without causing lateral erosion.
Solution Approach 2:
The film formed on the side wall acts as an intermediary protective layer between the etching environment and the opening structure. This intermediate film prevents direct contact between the etching agents and the opening walls, thereby suppressing lateral etching while allowing the etching process to continue.
2Ease of manufacture
If a uniform thickness film is formed on the side wall, then film formation simplicity is maintained, but shape abnormalities such as bowing and tapering occur
Solution Approach 1:
The film thickness is made non-uniform, with different thicknesses at different positions along the side wall. Specifically, the film is thicker at the upper portion and thinner at the lower portion of the opening. This local variation in film thickness compensates for shape abnormalities by providing greater support where needed, thereby correcting bowing and tapering effects.
3Quantity of substance
If the opening aspect ratio is increased for 3D NAND structures, then integration density is improved, but etching and film formation uniformity deteriorates
Solution Approach 1:
The film thickness is varied locally along the side wall, being thicker at the upper portion and thinner at the lower portion. This local quality variation compensates for the difficulties of forming uniform films in high aspect ratio openings, ensuring adequate coverage and protection where most needed while maintaining process feasibility.
Solution Approach 2:
The film formation parameters are changed to create a non-uniform thickness profile. By controlling deposition conditions, the film is formed with varying thickness along the side wall, which improves uniformity of the overall structure despite the high aspect ratio of the opening.
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 method effectively corrects shape abnormalities in high aspect ratio patterns, ensures uniformity of opening dimensions, and maintains high etching selectivity, thereby improving the accuracy and reliability of semiconductor manufacturing processes.
Implementation Method 1
forming a film having a thickness that differs along the film thickness direction of the mask, on a side wall of the opening
Data Source
AI summary
Provided is a method of processing a substrate including an etching target film and a mask having an opening formed on the etching target film. The method includes a) providing the substrate on a stage in a chamber and b) forming a film having a thickness that differs along a film thickness direction of the mask, on a side wall of the opening.