RF Bridge Assembly for PECVD Plasma Uniformity
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Solution Overview
Problem
Large area plasma enhanced chemical vapor deposition (PECVD) chambers face issues with plasma asymmetry due to slit valve openings, leading to inconsistencies in film thickness and properties, which existing solutions like single RF feed locations cannot adequately address, especially as chamber size increases.
Innovation Solution
An RF bridge assembly is used to equalize voltage and current distribution between multiple RF power feed locations, ensuring consistent application of RF power to the backing plate, thereby minimizing plasma asymmetry and maintaining consistent film properties across larger substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple RF power feed locations are used to accommodate larger substrates, then substrate coverage is improved, but plasma asymmetry increases due to unequal voltage and current distribution
Solution Approach 1:
The RF bridge assembly equalizes the voltage distribution between multiple RF feed locations on the backing plate, creating equipotential conditions that ensure uniform RF power delivery across the large substrate area, thereby maintaining film thickness uniformity while accommodating larger substrates
Solution Approach 2:
The RF bridge assembly acts as an intermediary component between the multiple RF feed locations and the backing plate, mediating the voltage and current distribution to eliminate asymmetry caused by the slit valve opening while enabling coverage of larger substrate areas
2Productivity
If RF power is applied at multiple locations to cover larger areas, then productivity is improved, but plasma asymmetry and film property inconsistency worsen
Solution Approach 1:
By establishing equipotential conditions through the RF bridge assembly, multiple RF feed locations can be utilized simultaneously to process larger substrates or multiple substrates, increasing productivity while ensuring consistent film properties through uniform voltage and current distribution at each feed location
3Adaptability or versatility
If the chamber size is increased to accommodate larger substrates, then adaptability is improved, but RF grounding and plasma distribution problems worsen
Solution Approach 1:
The RF bridge assembly provides a systematic approach to maintaining equipotential conditions in large chambers, simplifying the RF grounding and plasma distribution by ensuring uniform voltage distribution across the backing plate, thereby reducing system complexity despite increased chamber size and multiple feed locations
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 RF bridge assembly ensures that both current and voltage are substantially identical at multiple locations, reducing plasma asymmetry and enhancing the consistency of film thickness and properties, even with multiple RF feed points spaced from the center, thus improving the processing outcomes in large area PECVD chambers.
Implementation Method 1
A RF power source 128 is coupled to the backing plate 112 and/or to the showerhead 106 to provide a RF current to the showerhead 106. The RF current creates an electric field between the showerhead 106 and the substrate support 118 so that a plasma may be generated from the gases between the showerhead 106 and the substrate support 118.
Implementation Method 2
The RF current creates an electric field between the showerhead 106 and the substrate support 118 so that a plasma may be generated from the gases between the showerhead 106 and the substrate support 118.
Implementation Method 3
In order to ensure that both the current and voltage are substantially identical at multiple locations where the RF power is delivered to the backing plate, an RF bridge assembly may be coupled between the multiple locations at a location just before connection to the backing plate. The RF bridge assembly substantially equalizes the voltage distribution and current distribution between the multiple locations.
Data Source
AI summary
Embodiments disclosed herein generally relate to a PECVD apparatus. When the RF power source is coupled to the electrode at multiple locations, the current and voltage may be different at the multiple locations. In order to ensure that both the current and voltage are substantially identical at the multiple locations, an RF bridge assembly may be coupled between the multiple locations at a location just before connection to the electrode. The RF bridge assembly substantially equalizes the voltage distribution and current distribution between multiple locations. Therefore, a substantially identical current and voltage is applied to the electrode at the multiple locations.