Plasma Etching Substrate Openings with Non-Vertical Sidewalls
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Solution Overview
Problem
Current methods for forming substrate openings in semiconductor processing are limited in precision and efficiency, particularly in achieving consistent and varied depths of side-by-side openings and non-vertical sidewall surfaces, which are crucial for advanced integrated circuitry and other structures.
Innovation Solution
The method involves using plasma etching with a single masking step to form side-by-side openings of varying depths in a semiconductor substrate, followed by removing the walls between these openings to create a larger opening with a non-vertical sidewall surface, utilizing etch masks with varying minimum widths and adjusting etching conditions to achieve specific geometries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple masking steps are used to form openings of varying depths, then manufacturing precision is improved, but device complexity and processing time increase
Solution Approach 1:
The single masking layer is segmented into multiple regions with different etch resistances or etch rates, allowing different opening depths to be formed simultaneously through one etching process. This segmentation approach enables varying opening depths without requiring multiple masking steps, thereby maintaining manufacturing precision while reducing process complexity.
Solution Approach 2:
Different portions of the masking layer are designed with locally different properties (such as varying thickness, material composition, or pattern density) to control the etching rate in each region. This local quality variation allows the etching process to naturally create openings of different depths through a single step, eliminating the need for multiple masking operations.
2Ease of manufacture
If conventional etching methods are used, then process simplicity is maintained, but manufacturing precision for non-vertical sidewalls deteriorates
Solution Approach 1:
The etching process parameters (such as gas composition, pressure, power, or temperature) are dynamically changed during the etching sequence to transform the sidewall geometry from vertical to non-vertical. By adjusting these parameters mid-process, the method achieves precise control over sidewall angles while maintaining the simplicity of a single continuous etching operation without requiring multiple process steps.
3Manufacturing precision
If multiple etching steps are performed to create complex geometries, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
Multiple etching operations that would traditionally be performed in separate steps are merged into a single continuous etching process. The masking layer design and etching parameter control enable the formation of multiple opening types (different depths, different sidewall geometries) simultaneously in one process run, thereby maintaining manufacturing precision while significantly improving productivity by eliminating intermediate steps.
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 allows for the precise formation of substrate openings with non-vertical sidewall surfaces, enabling the creation of complex geometries and structures that enhance the density and performance of integrated circuitry and other devices.
Implementation Method 1
A plurality of side-by-side openings is plasma etched into the substrate using the etch mask
Data Source
AI summary
A method of forming a substrate opening includes forming a plurality of side-by-side openings in a substrate. At least some of immediately adjacent side-by-side openings are formed in the substrate to different depths relative one another. Walls that are laterally between the side-by-side openings are removed to form a larger opening having a non-vertical sidewall surface where the walls were removed in at least one straight-line vertical cross-section that passes through the sidewall surface orthogonally to the removed walls.