Electrostatic Edge Ring Holding with Polarity Switching After Plasma
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Solution Overview
Problem
Plasma processing apparatuses face challenges in effectively holding edge rings during and after substrate processing, leading to potential misalignment issues when transferring new substrates due to charge migration and inadequate cleaning processes.
Innovation Solution
A method involving the application of specific voltage polarities and sequences to the electrodes of an electrostatic chuck to hold and release edge rings, utilizing positive and negative voltages to prevent charge migration and ensure proper cleaning, with the first voltage having a positive polarity during plasma processing and a second voltage with negative polarity during chamber cleaning, followed by a third and fourth voltage with positive and negative polarities respectively in a subsequent cleaning period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the same polarity voltage is applied to both electrodes of the electrostatic chuck, then the edge ring can be held stably during plasma processing, but charge migration occurs after processing leading to substrate misalignment
Solution Approach 1:
The patent applies periodic voltage polarity switching to the electrostatic chuck electrodes. During plasma processing, a first polarity voltage is applied to hold the edge ring stably. After processing, the voltage polarity is inverted to a second polarity to prevent charge migration. This periodic action resolves the contradiction by maintaining holding stability during processing while eliminating charge accumulation that causes misalignment afterward.
Solution Approach 2:
The patent changes the voltage parameter (polarity) applied to the electrostatic chuck electrodes based on processing stage. By switching between first polarity during plasma processing and second polarity during post-processing, the system maintains edge ring holding stability while preventing charge migration-induced substrate misalignment.
2Reliability
If the electrostatic chuck holds the edge ring tightly during plasma processing, then processing stability is improved, but chamber cleaning efficiency decreases due to restricted plasma access
Solution Approach 1:
The patent uses periodic voltage application to the electrostatic chuck. During plasma processing, voltage is applied to hold the edge ring tightly for processing stability. During chamber cleaning periods, the voltage is removed or reduced to allow plasma access for efficient cleaning. This periodic control resolves the contradiction between holding stability and cleaning efficiency.
3Manufacturing precision
If different polarity voltages are applied to prevent charge migration, then substrate alignment precision is improved, but edge ring holding force decreases
Solution Approach 1:
The patent applies different polarity voltages at different time periods. During plasma processing, a first polarity voltage provides strong holding force. After processing, the polarity is inverted to a second polarity that prevents charge migration while maintaining sufficient holding force. This temporal separation resolves the contradiction between holding force and alignment precision.
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 method effectively prevents substrate misalignment by managing charge distribution and ensuring thorough chamber cleaning, maintaining the edge ring's position and facilitating smooth substrate transfer.
Implementation Method 1
The electrostatic chuck of each of the plasma processing apparatuses disclosed in Japanese Unexamined Patent Publication No. 2016-122740 and Japanese Unexamined Patent Publication No. 2018-206935 has two electrodes in order to hold an edge ring. The edge ring is held by the electrostatic chuck by applying voltages of the same polarity or different polarities to the two electrodes.
Implementation Method 2
In the first period, cleaning of the chamber is performed using a plasma generated in the chamber.
Data Source
AI summary
A first electrostatic chuck of a substrate support of the disclosed plasma processing apparatus has first and second electrodes and holds an edge ring. A second electrostatic chuck of the substrate support holds a substrate. The first electrode extends closer to the second electrostatic chuck than the second electrode. During plasma processing, a first voltage having a positive polarity is applied to the first and second electrodes. In a first period after the plasma processing, a second voltage having a negative polarity is applied to the first and second electrodes. In a second period after the first period, a third voltage having a positive polarity is applied to the first electrode, and a fourth voltage having a negative polarity is applied to the second electrode. The absolute value of the third voltage is smaller than the absolute value of the first voltage and the absolute value of the second voltage.