Electrostatic Chuck Temperature Control for Plasma Particle Prevention
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Solution Overview
Problem
The existing plasma processing methods generate particles due to thermal expansion differences between wafers and electrostatic chucks, which complicate apparatus structure and process, and existing methods to control these differences are not effective in preventing particle generation.
Innovation Solution
A method and apparatus where the electrostatic chuck's temperature is controlled in a step-by-step manner from a first temperature to a second, lower temperature after the plasma process, while purging the processing chamber with an inactive gas to minimize thermal expansion differences and prevent particle generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrostatic chuck is preliminarily heated to high temperature to enhance plasma processing performance, then plasma processing performance is improved, but thermal expansion difference causes wafer back surface to rub against the chuck generating particles
Solution Approach 1:
The electrostatic chuck is preliminarily heated to high temperature before plasma processing to enhance processing performance. This preliminary heating action prepares the chuck in advance to achieve the desired plasma processing results while managing thermal expansion effects.
Solution Approach 2:
The electrostatic chuck undergoes periodic temperature adjustments - heating to high temperature during plasma processing and then cooling down afterward. This periodic cycling allows the system to achieve high processing performance when needed while reducing thermal expansion differences during non-processing periods, thereby preventing particle generation.
2Object-generated harmful factors
If the temperature difference between wafer and electrostatic chuck is controlled within predetermined range to prevent particle generation, then particle generation is prevented, but apparatus structure and process become complicated due to preliminary heating chamber requirement
Solution Approach 1:
The electrostatic chuck serves multiple functions: it acts as both the processing platform and the temperature control device. By integrating heating and cooling capabilities directly into the chuck, the system eliminates the need for a separate preliminary heating chamber, thereby simplifying the overall apparatus structure while still preventing particle generation through controlled temperature differences.
Solution Approach 2:
The system dynamically adjusts the temperature parameter of the electrostatic chuck based on processing requirements. By changing the temperature parameter in a controlled manner - heating before processing and cooling afterward - the system maintains temperature difference within acceptable ranges to prevent particle generation without requiring complex additional apparatus.
3Temperature
If the temperature of electrostatic chuck is reduced after plasma process, then thermal expansion difference is minimized, but particle generation may occur during temperature transition if not purged properly
Solution Approach 1:
An inactive gas is introduced as an intermediary medium during the temperature transition phase. This gas creates a protective atmosphere that prevents particle generation while the electrostatic chuck temperature is being reduced. The inactive gas acts as a mediator between the changing temperature conditions and the wafer-chuck interface, ensuring no particles are generated during the transition.
Solution Approach 2:
The system performs a purge operation with inactive gas before and during the temperature reduction phase. This beforehand cushioning with protective gas prevents particle generation that might occur during thermal contraction, ensuring the wafer back surface does not rub against the chuck as temperatures equalize.
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
Effectively prevents particle generation by maintaining minimal thermal expansion differences between the wafer and electrostatic chuck, simplifying the apparatus structure and process by controlling temperature adjustments in a controlled and efficient manner.
Implementation Method 1
an electrostatic chuck configured to have its temperature adjustable
Implementation Method 2
there occurs a thermal expansion difference between the wafer and the electrostatic chuck due to the temperature difference
Implementation Method 3
An inside of the processing chamber is purged with an inactive gas after performing the plasma process
Data Source
AI summary
A method of controlling a temperature is provided. In the method, a plasma process is performed in a processing chamber on an object to be processed placed on an electrostatic chuck configured to have its temperature adjustable. The electrostatic chuck is controlled to have a first temperature. The temperature of the electrostatic chuck is controlled in a step-by-step manner so as to change from the first temperature to a second temperature that is lower than the first temperature after performing the plasma process. An inside of the processing chamber is purged with an inactive gas after performing the plasma process.