Self-Limiting Cyclic Etch for Carbon Films
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Solution Overview
Problem
Conventional plasma etching processes for carbon-based films in semiconductor manufacturing face challenges in achieving global and local uniformity due to trade-offs in etch rate, profile control, and uniformity, particularly with oxygen plasma radicals leading to critical dimension loss.
Innovation Solution
A cyclic etch method involving alternating exposure of carbon-based films to a first plasma forming an activated layer and a second non-activating inert gas plasma to form a carbonized layer, with self-limiting processes to control etch rate and uniformity, and optional use of silylating agents to enhance silicon incorporation and passivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If oxygen plasma radicals are used to achieve high etch rates, then etch rate is improved, but critical dimension loss occurs leading to poor manufacturing precision
Solution Approach 1:
The continuous plasma etch process is segmented into cyclic alternating steps: an activating step that forms an oxidized layer on the carbon-based film, followed by a removing step that selectively removes the oxidized layer. This segmentation allows control over etch rate and CD uniformity independently, resolving the contradiction between high etch rate and critical dimension precision.
Solution Approach 2:
The patent employs periodic cyclic plasma treatment with alternating activating and removing steps. The activating step creates an oxidized layer, and the removing step selectively etches it away. This periodic action enables precise control of etch rate and critical dimension uniformity by adjusting cycle parameters, overcoming the limitations of continuous plasma etching.
2Productivity
If conventional continuous plasma processes are used, then etch rate can be maintained, but global and local uniformity control becomes problematic due to trade-offs in plasma species distribution
Solution Approach 1:
The plasma etch process is divided into distinct cyclic steps: an activating plasma step that forms an oxidized layer, and a removing plasma step that selectively removes it. This segmentation allows independent optimization of each step for uniformity and etch rate, eliminating the trade-offs inherent in continuous plasma processes where plasma species distribution affects both etch rate and uniformity simultaneously.
Solution Approach 2:
The patent changes plasma parameters cyclically between activating and removing steps. The activating step uses plasma conditions optimized for oxidized layer formation with good uniformity, while the removing step uses different plasma conditions optimized for selective removal. This parameter cycling resolves the uniformity-etch rate trade-off by decoupling the two functions into separate 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
The cyclic etch method significantly reduces global and local non-uniformities, achieving etch rate uniformity and profile control, with global vertical etch rate non-uniformity and aspect ratio-dependent etching defects minimized, improving the precision of semiconductor device manufacturing.
Implementation Method 1
exposing the carbon-based film to a first process gas thereby forming an activated layer on the carbon-based film
Implementation Method 2
the first process gas includes a first plasma formed by plasma-exciting a process gas consisting of O2 gas
Implementation Method 3
exposing the activated layer to a second process gas comprising a plasma thereby removing the activated layer and forming a carbonized layer on the carbon-based film, wherein the plasma is a non-activating inert gas
Implementation Method 4
forming a carbonized layer on the carbon-based film
Implementation Method 5
the formation of the activated layer and the formation of the carbonized layer are self-limiting processes
Data Source
AI summary
Embodiments of the disclosure describe a cyclic etch method for carbon-based films. According to one embodiment, the method includes providing a substrate containing the carbon-based film, exposing the carbon-based film to an oxidizing plasma thereby forming an oxidized layer on the carbon-based film, thereafter, exposing the oxidized layer to a non-oxidizing inert gas plasma thereby removing the oxidized layer and forming a carbonized surface layer on the carbon-based film, and repeating the exposing steps at least once.