Selective Silicon Oxide Etching via Fluorocarbon Plasma Power Control
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Solution Overview
Problem
Conventional etching methods for silicon oxide relative to silicon nitride often result in unintended etching of the silicon nitride region due to the lack of a protective film, leading to damage during the etching process of silicon oxide.
Innovation Solution
An etching method using plasma processing with a fluorocarbon gas, where the first region of silicon oxide is etched by radicals formed on the surface, with controlled high-frequency power settings to minimize etching of the second region of silicon nitride, employing a deposition mode to protect the nitride region and an etching mode for the oxide region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If plasma processing is performed to etch silicon oxide region, then etching of silicon oxide is achieved, but unintended etching of silicon nitride region occurs due to lack of protective film
Solution Approach 1:
A protective film is formed on the silicon nitride region before the etching process begins. This preliminary action ensures that when plasma processing is subsequently performed to etch the silicon oxide region, the silicon nitride region is already protected and will not suffer from unintended etching or damage.
Solution Approach 2:
A protective film is introduced as an intermediary layer between the plasma processing environment and the silicon nitride region. This intermediary film acts as a barrier that allows the plasma to etch the silicon oxide while preventing direct contact and damage to the silicon nitride region.
2Productivity
If high frequency power is increased to improve etching rate of silicon oxide, then productivity increases, but etching of silicon nitride region is exacerbated
Solution Approach 1:
Different regions of the substrate are treated with different qualities - the silicon oxide region receives high-frequency plasma processing for rapid etching, while the silicon nitride region is selectively protected. This local differentiation allows high productivity in the oxide region without compromising selectivity or causing damage to the nitride region.
Solution Approach 2:
The plasma processing parameters are changed and optimized to achieve selective etching. By adjusting parameters such as gas composition, pressure, and power distribution, the process is tuned to etch silicon oxide at high rates while minimizing or preventing etching of silicon nitride, thus maintaining both productivity and selectivity.
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
Effectively etches the silicon oxide region while suppressing etching of the silicon nitride region, ensuring precise control and minimizing damage to the nitride layer.
Implementation Method 1
a plasma of a processing gas including a fluorocarbon gas is generated in a processing chamber where the target object is accommodated
Implementation Method 2
the first region is etched by radicals of fluorocarbon contained in a deposit which is formed on the target object by the generation and the further generation of the plasma
Implementation Method 3
A high frequency powers used for the plasma generation is smaller than a high frequency power used for plasma further generation
Data Source
AI summary
An etching method is provided for selectively etching a first region of silicon oxide with respect to a second region of silicon nitride by performing plasma processing on a target object including the first region and the second region. In the etch method, first, a plasma of a processing gas including a fluorocarbon gas is generated in a processing chamber where the target object is accommodated. Next, the plasma of the processing gas including the fluorocarbon gas is further generated in the processing chamber where the target object is accommodated. Next, the first region is etched by radicals of fluorocarbon contained in a deposit which is formed on the target object by the generation and the further generation of the plasma of the processing gas containing the fluorocarbon gas. A high frequency powers used for the plasma generation is smaller than a high frequency power used for plasma further generation.