Sacrificial Mask Layer Reshaping for Stable Plasma Etching
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Solution Overview
Problem
During plasma etching, the mask layer deforms, leading to undesirable effects such as ion scattering, sputtering, and re-deposition, which can result in critical dimension variability, line edge roughness, and decreased process yield due to changes in the mask layer's shape and thickness.
Innovation Solution
A sacrificial layer is deposited on the mask layer to reshape it by inhibiting etching or deposition, using a material with a higher etch rate than the mask layer, and then removed during the target material etching process, maintaining the mask layer's thickness and shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the mask layer is used during plasma etching, then the target material can be etched with selective removal, but the mask layer deforms and changes shape causing ion scattering, sputtering, and re-deposition
Solution Approach 1:
A sacrificial layer is deposited on the mask layer before the plasma etching process begins. This preliminary action prepares the mask structure to maintain its shape during etching by providing a protective barrier that prevents direct interaction between the plasma and the mask layer, thereby preventing deformation while allowing selective etching of the target material.
Solution Approach 2:
The sacrificial layer acts as an intermediary between the plasma etching process and the mask layer. It mediates the interaction by absorbing the harmful effects of plasma exposure (ion scattering, sputtering, re-deposition) while allowing the mask layer to maintain its original shape and function. The sacrificial layer is designed to be removed after serving its protective purpose.
2Manufacturing precision
If the mask layer thickness is reduced to improve resolution, then the etch selectivity is maintained, but the mask layer becomes more susceptible to deformation and damage
Solution Approach 1:
The sacrificial layer is deposited in advance on the thin mask layer to provide immediate protection against plasma-induced deformation. This preliminary protective measure enables the use of thinner mask layers for higher resolution etching without compromising their stability during the etching process.
Solution Approach 2:
The sacrificial layer serves as a cushioning barrier deposited beforehand to absorb the mechanical and chemical stresses of plasma etching. This prior cushioning protects the thin mask layer from deformation, sputtering, and re-deposition, thereby maintaining both the thin profile needed for resolution and the stability needed for reliable etching.
3Productivity
If the etching process continues with the deformed mask, then the target material etching is completed, but the final etched features have undesirable effects due to mask deformation
Solution Approach 1:
The sacrificial layer is prepared in advance to prevent mask deformation during the entire etching process. This preliminary protective measure ensures that the mask layer maintains its original pattern and dimensions throughout the etching operation, thereby producing precise etched features while maintaining high productivity.
Solution Approach 2:
The sacrificial layer mediates the etching process by protecting the mask layer from deformation while allowing the etching to proceed efficiently. This intermediary protection ensures that the final etched features accurately reflect the intended mask pattern, eliminating defects caused by mask deformation and improving overall manufacturing precision.
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 prevents deformation of the mask layer, maintaining etch selectivity and reducing defects, thereby improving the precision and yield of the plasma etching process.
Implementation Method 1
depositing on the patterned mask layer a sacrificial layer including a third material
Implementation Method 2
Plasma etch of a target material to form a patterned structure
Implementation Method 3
ion scattering, sputtering, and re-deposition behavior
Data Source
AI summary
Provided herein are methods and related apparatus for mask reconstruction in an etch process. The methods involve depositing a sacrificial layer on the mask layer. The sacrificial layer may be used to protect portions of the mask layer during reshaping by inhibiting etching of or deposition on the mask layer position on the mask layer. Following mask reshaping, the sacrificial layer may be removed using the same etch process that is used to etch the target material.