Reverse-Tapered Mask Etching for Vertical High-Aspect Patterns
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Solution Overview
Problem
In semiconductor manufacturing, high aspect ratio patterns are challenging to etch with vertical processability and shape abnormality issues due to the adherence of protective films and deposits during the etching process, especially when using vertical or tapered masks.
Innovation Solution
A substrate processing method involving a substrate with an etching target film, a first mask, and a second mask of different film types, where the first mask is selectively etched to create an opening with a larger dimension than the second mask's bottom, using ion modification atomic layer etching to achieve a reverse tapered shape and improve vertical processability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a vertical mask or tapered mask is used for high aspect ratio pattern etching, then the etching process can be performed, but shape abnormalities occur due to shadowing from adhered protective films and deposits
Solution Approach 1:
The patent inverts the conventional mask shape from vertical or tapered to reverse tapered (wider at bottom, narrower at top). This inversion allows etching ions to approach the etching target film more directly, reducing shadowing effects from deposits on the mask surface and improving vertical processability of high aspect ratio patterns
Solution Approach 2:
The patent changes the geometric parameters of the mask by forming a reverse tapered shape where the opening dimension at the bottom is larger than at the top. This parameter change optimizes the angle of incident ions during etching, enabling better access to the bottom of high aspect ratio structures and reducing shape abnormalities
2Ease of manufacture
If conventional single mask etching is used, then the process is simple, but vertical processability deteriorates for high aspect ratio patterns
Solution Approach 1:
The patent segments the mask structure into two distinct masks with different film types and functions. The first mask provides the reverse tapered shape for improved ion access, while the second mask maintains the opening for pattern definition. This segmentation enables both vertical processability and reasonable process complexity
Solution Approach 2:
The patent implements a nested mask structure where the first mask is formed on the etching target film and the second mask is formed on the first mask. The opening in the second mask aligns with the reverse tapered opening in the first mask, creating a nested configuration that achieves superior etching performance
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 enhances the vertical processability of patterns on the substrate, suppressing shape abnormalities by ensuring that the etching target film is processed vertically with reduced shadowing from deposits, thereby improving the accuracy of high aspect ratio pattern formation.
Implementation Method 1
selectively etching the first mask with respect to the second mask, thereby forming an opening in the first mask
Implementation Method 2
selectively etching the first mask with respect to the second mask
Implementation Method 3
etching the etching target film
Data Source
AI summary
A substrate processing method includes: (a) providing a substrate including an etching target film, a first mask formed on the etching target film, and a second mask formed on the first mask, the second mask being different in film type from the first mask and having an opening; (b) selectively etching the first mask with respect to the second mask, thereby forming an opening in the first mask such that an opening dimension of at least a portion of the first mask is larger than an opening dimension of a bottom of the second mask; and (c) etching the etching target film.