Atomic Layer Etch for Vertical Sidewalls
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Solution Overview
Problem
Conventional patterning techniques in semiconductor manufacturing, such as double patterning, face challenges in achieving vertical sidewalls due to isotropic damage and pitch walking, leading to inconsistent patterns and inefficiencies in trimming carbon-containing materials.
Innovation Solution
The method involves atomic layer etching of semiconductor substrates using an oxygen-containing gas without plasma to modify the surface, followed by exposure to an inert gas with plasma ignition, allowing for layer-by-layer etching to achieve vertical sidewalls, and subsequent conformal film deposition without breaking vacuum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional isotropic etching techniques are used, then the etching process is simple and fast, but isotropic damage and pitch walking occur leading to poor manufacturing precision
Solution Approach 1:
The etching process is segmented into multiple sequential steps: (1) oxygen plasma treatment to modify the carbon-containing material surface, (2) inert gas plasma etching to remove the modified layer, with cycles repeated to achieve desired etch depth. This segmentation enables precise control over etching progression and sidewall formation, eliminating the isotropic damage of conventional single-step etching.
Solution Approach 2:
The etching process employs periodic alternating exposure to oxygen-containing plasma and inert gas plasma. The oxygen plasma modifies the surface chemistry to make it more susceptible to etching, followed by inert gas plasma that performs the actual material removal. This periodic action pattern enables controlled, anisotropic etching with vertical sidewalls.
2Manufacturing precision
If atomic layer etching with multiple steps is used, then manufacturing precision and vertical sidewalls are achieved, but process time and complexity increase
Solution Approach 1:
The process parameters including gas flow rates, plasma power, pressure, and temperature are optimized to achieve maximum etch rate per cycle while maintaining vertical sidewalls. By carefully controlling these parameters, the number of cycles required is minimized, reducing total process time while preserving manufacturing precision.
Solution Approach 2:
The atomic layer etching process maintains continuous vacuum conditions throughout all steps without breaking vacuum between operations. The sequential plasma exposures and purges occur continuously, eliminating idle time and maximizing the useful action time, thereby reducing overall process duration despite the multiple steps involved.
3Reliability
If conventional etching is used, then the process is straightforward, but pitch walking and isotropic damage lead to inconsistent patterns
Solution Approach 1:
Oxygen-containing plasma acts as an intermediary that modifies the carbon-containing material surface before the actual etching by inert gas plasma. This intermediary step creates a chemically modified surface layer that etches uniformly and anisotropically, preventing pitch walking and ensuring consistent patterns across the substrate.
Solution Approach 2:
The conventional mechanical/physical isotropic etching is replaced with a chemical modification approach using oxygen plasma, followed by controlled chemical etching with inert gas plasma. This substitution of the etching mechanism enables directional, anisotropic removal of material with vertical sidewalls, eliminating the pitch walking problem inherent in isotropic processes.
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 prevents isotropic damage and pitch walking, enabling precise reduction of critical dimensions and consistent vertical sidewalls, enhancing the efficiency and accuracy of patterning processes like double and quad patterning.
Implementation Method 1
exposing the surface of the carbon-containing features to an oxygen-containing gas without a plasma to modify the surface of the carbon-containing material
Implementation Method 2
exposing the modified surface of the carbon-containing features to an inert gas and igniting a plasma to move the modified surface of the carbon-containing features
Data Source
AI summary
Methods and apparatuses for patterning carbon-containing material over a layer to be etched are provided herein. Methods involve trimming carbon-containing material by atomic layer etching including exposing the carbon-containing material to an oxygen-containing gas without a plasma to modify a surface of the carbon-containing material and exposing the carbon-containing material to an inert gas and igniting a plasma to remove the modified surface of the carbon-containing material. Methods may be used for multiple patterning techniques such as double and quad patterning. Methods also include depositing a conformal film over a carbon-containing material patterned using atomic layer etching without breaking vacuum.