Remote Plasma Etching with Separate Hydrogen Atmosphere Control
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Solution Overview
Problem
The stability of plasma and reproducibility of the process are compromised when the flow rate of hydrogen-based gases is changed, making it difficult to expand the process margin during substrate processing, particularly in selectively removing silicon compared to oxide layers.
Innovation Solution
An apparatus and method are developed that involve generating plasma using a fluorine-based gas in a separate plasma generating region, while maintaining a hydrogen atmosphere in the process region using a constant flow rate of hydrogen-based gas. This approach ensures high plasma stability and process reproducibility by controlling the etch selectivity between silicon and oxide layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the flow rate of hydrogen-based gas is changed to adjust etch selectivity, then the selectivity between silicon and oxide layers is improved, but the stability of plasma and process reproducibility deteriorate
Solution Approach 1:
The apparatus is divided into a plasma generating region and a process region, allowing independent control of hydrogen-based gas flow rates in each region. This segmentation enables the process region to maintain stable plasma conditions while the plasma generating region provides the necessary reactive species for etching, thus resolving the contradiction between selectivity adjustment and plasma stability
Solution Approach 2:
The invention changes the parameter of hydrogen-based gas flow rate differently in the plasma generating region versus the process region. By maintaining a first flow rate in the plasma generating region and a second flow rate in the process region, the system can optimize both plasma stability and etch selectivity simultaneously, overcoming the limitation of using a single flow rate control
2Manufacturing precision
If the flow rate of hydrogen-based gas is changed to adjust etch selectivity, then the selectivity between silicon and oxide layers is improved, but the process reproducibility deteriorates
Solution Approach 1:
By segmenting the gas flow control into two independent regions (plasma generating region and process region), the invention allows reproducible plasma conditions to be maintained in the process region through stable second flow rate control, while selectivity is optimized through the first flow rate in the plasma generating region
Solution Approach 2:
The plasma generating region acts as an intermediary that produces reactive fluorine species which are then transported to the process region. This intermediary role allows the system to decouple the control of plasma generation (affecting selectivity) from plasma maintenance (affecting reproducibility), enabling both requirements to be satisfied
3Device complexity
If a single gas flow rate is used for hydrogen-based gas, then the device complexity is reduced, but the ability to expand process margin is limited
Solution Approach 1:
The gas flow control system is segmented into two independent control channels, one for the plasma generating region and another for the process region. This segmentation provides additional degrees of freedom for process optimization, enabling expansion of process margin while maintaining manageable device complexity through modular control architecture
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 method achieves high plasma stability and process reproducibility, allowing for effective selective removal of silicon layers compared to oxide layers, thereby expanding the process margin and ensuring consistent results.
Implementation Method 1
generating plasma by providing a fluorine-based gas to the plasma generating region
Implementation Method 2
a plasma generating module including a plasma generating region and a first gas providing unit for providing a first gas to the plasma generating region, the plasma generating module using the first gas to generate plasma in the plasma generating region
Implementation Method 3
providing the generated plasma to the process region to selectively remove the silicon layer compared to the oxide layer
Implementation Method 4
selectively remove silicon (e.g., polysilicon) compared to oxide (e.g., SiO2), plasma may be generated using a fluorine-based gas
Data Source
AI summary
An apparatus and method for processing a substrate using plasma, which has high plasma stability and process reproducibility, is provided. The method includes providing an apparatus for processing a substrate comprising a plasma generating region and a process region separate from the plasma generating region, placing the substrate including a silicon layer and an oxide layer in the process region, forming a hydrogen atmosphere in the process region by providing a hydrogen-based gas to the process region without passing through the plasma generating region, generating plasma by providing a fluorine-based gas to the plasma generating region, and providing the generated plasma to the process region to selectively remove the silicon layer compared to the oxide layer.