Plasma Reactor Vessel Third Electrode Clearance Gap
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Solution Overview
Problem
Conventional plasma processing techniques face challenges in achieving uniformity and avoiding contamination when processing both sides of a substrate in a single vacuum sequence, as physical contact with electrodes can lead to contamination and non-uniform plasma distribution due to clearance gaps, and mechanical flipping risks substrate breakage.
Innovation Solution
A plasma reactor vessel design with a substrate carrier that maintains the majority of the substrate's upper and lower surfaces untouched by the reactor, using a third electrode with a clearance gap and compensating RF voltage to ensure uniform plasma exposure across both surfaces without flipping the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the substrate is in physical contact with the back-plate electrode for voltage setting, then good voltage continuity is achieved, but substrate contamination occurs due to friction contact
Solution Approach 1:
A dielectric layer is introduced as an intermediary between the substrate and the back-plate electrode. This dielectric layer prevents direct physical contact and contamination while still allowing electrical connection through conductive paste applied to the substrate's rear surface, which contacts the dielectric and establishes voltage setting without friction-induced contamination
Solution Approach 2:
The mechanical direct-contact system is replaced with a hybrid system combining dielectric insulation and conductive paste electrical connection. This substitution eliminates the need for friction-based mechanical contact while maintaining voltage continuity through the conductive paste path
2Adaptability or versatility
If the substrate is flipped to process both sides, then both surfaces can be processed, but substrate breakage risk increases due to mechanical handling
Solution Approach 1:
The processing approach transitions from sequential single-side processing (requiring flipping) to simultaneous dual-side processing. By applying RF power to both the front and back electrodes concurrently, plasma is generated on both sides of the substrate at the same time, eliminating the need for mechanical flipping and associated breakage risks
Solution Approach 2:
The processing of both substrate sides is merged into a single continuous operation. The reactor configuration allows plasma deposition on the front surface and back surface to occur simultaneously during one vacuum cycle, combining what would traditionally require separate processing steps and substrate repositioning
3Object-affected harmful factors
If a clearance gap is introduced between substrate and back-plate to avoid contamination, then contamination is reduced, but plasma uniformity deteriorates due to non-uniform distribution
Solution Approach 1:
Different regions of the substrate are treated with different contact characteristics. The peripheral region maintains contact with the back-plate through the dielectric layer for voltage setting and plasma uniformity, while the central active area remains separated to avoid contamination. This local differentiation allows simultaneous achievement of plasma uniformity and contamination prevention
Solution Approach 2:
The electrical connection parameter is changed from direct mechanical contact to dielectric-based contact with conductive paste. This parameter change allows the substrate to be held at the correct RF voltage potential without the harmful effects of direct friction contact, maintaining plasma uniformity while preventing contamination
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 design allows for uniform plasma processing of both substrate surfaces in a single vacuum sequence, reducing contamination risks and avoiding substrate breakage, while maintaining uniform plasma distribution and deposition quality.
Implementation Method 1
a power source electrically connected to one of the first or second electrodes, for applying a main RF voltage to one of the first or second electrodes
Implementation Method 2
Plasma 5 is made of the ionized fraction of a low pressure background gas
Implementation Method 3
a substrate carrier (13) which is configured to hold a substrate (11) at a defined position relative to the first and second electrodes
Data Source
AI summary
Plasma reactor vessel comprising a vacuum chamber; a first electrode in the vacuum chamber; a second electrode in the vacuum chamber, opposed to the first electrode and spaced from the first electrode; a power source electrically connected to one of the first or second electrodes; a substrate carrier having an electrically conductive material, the substrate carrier being configured to be in electrical contact with the second electrode and to hold a substrate at such that at least the majority of upper and lower surfaces of the substrate are untouched by any part of the plasma reactor and can be exposed to the plasma. The reactor vessel further includes a third electrode between the substrate carrier and the second electrode, wherein the third electrode is electrically insulated from the second electrode. And the third electrode and the substrate carrier are arranged such that when the substrate carrier holds a substrate, a first clearance gap is between the substrate and the third electrode. There is further provided a corresponding assembly and method for performing plasma processing.