Remote Plasma Hollow Cathode Discharge for Semiconductor Etching
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Solution Overview
Problem
Conventional semiconductor processing technologies face challenges in achieving high selectivity and minimizing damage to substrates during etching, often resulting in lower quality devices due to lower gas pressures, lower ion and radical densities, and electrode damage.
Innovation Solution
The use of a hollow cathode discharge in combination with a glow discharge in a semiconductor processing system, where a hollow cathode discharge is generated by flowing gas through a conical cavity with a powered electrode and reacting the effluents with the substrate, allowing for higher radical and ion densities and increased selectivity, while reducing electrode damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If local plasma is used for etching, then trench penetration and structure deformation are improved, but substrate damage increases due to electric arcs
Solution Approach 1:
The plasma generation is segmented into two separate regions: a remote plasma generation chamber and a substrate processing chamber. The plasma is generated remotely and transported to the substrate region without direct contact, eliminating electric arcs at the substrate interface while maintaining effective etching capability.
Solution Approach 2:
A remote plasma source acts as an intermediary, generating reactive species that are transported through a controlled medium to the substrate region. This intermediary approach allows plasma chemistry to be optimized separately from substrate processing conditions, reducing direct plasma-related damage.
2Productivity
If conventional plasma discharge is used, then etching process is achieved, but electrode damage occurs reducing equipment uptime
Solution Approach 1:
The plasma generation function is extracted from the substrate processing region and placed in a separate remote chamber. This separation removes the electrode damage issue from the substrate processing system, as electrodes are now isolated in a dedicated plasma generation zone that can be maintained separately.
Solution Approach 2:
The system transitions from a single-chamber direct plasma approach to a multi-chamber remote plasma approach, adding spatial separation as a new dimension. This allows independent optimization of plasma generation conditions and substrate processing conditions, protecting the substrate region from electrode-related issues.
3Quantity of substance
If higher gas pressure is used in hollow cathode discharge, then electron impact ionization rate increases, but discharge stability becomes more challenging
Solution Approach 1:
The system utilizes specific pressure ranges (0.1-10 Torr) optimized for hollow cathode discharge operation. By carefully controlling pressure as a key parameter, the system achieves high electron impact ionization rates while maintaining discharge stability through the confining geometry of the hollow cathode structure.
Solution Approach 2:
The hollow cathode structure creates localized regions of high electron density and ionization within its cavity, while the overall chamber maintains stable, controlled conditions. This local quality enhancement allows high ionization rates in specific zones without compromising overall discharge stability.
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 enhances etching efficiency, increases process reliability, and reduces substrate damage, leading to improved semiconductor device performance and longer equipment uptime by increasing electron impact ionization and controlling reaction chemistries.
Implementation Method 1
A hollow cathode discharge may be a plasma discharge that increases the electron impact ionization rate at the center of a hollow cathode
Implementation Method 2
Generating a hollow cathode discharge for semiconductor processing, and possibly alternating generation of the hollow cathode discharge with generation of a glow discharge in the same processing chamber
Implementation Method 3
generation of a glow discharge in the same processing chamber
Data Source
AI summary
Embodiments of the present technology may include a method of processing a semiconductor substrate. The method may include providing the semiconductor substrate in a processing region. Additionally, the method may include flowing gas through a cavity defined by a powered electrode. The method may further include applying a negative voltage to the powered electrode. Also, the method may include striking a hollow cathode discharge in the cavity to form hollow cathode discharge effluents from the gas. The hollow cathode discharge effluents may then be flowed to the processing region through a plurality of apertures defined by electrically grounded electrode. The method may then include reacting the hollow cathode discharge effluents with the semiconductor substrate in the processing region.