Monopolar Electrostatic Chuck Plasma Etching Particle Control
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Solution Overview
Problem
During plasma etching, by-products from plasma reactions fall onto the substrate or are deposited on the chamber walls, forming particles on the substrate surface, which can contaminate the etched surface.
Innovation Solution
A plasma etching method using a monopolar electrostatic chuck to attract a substrate with a noble gas plasma and then etch using a halogen-based plasma, with voltage polarity reversal to inhibit particle formation, where the first plasma generation stops with a positive voltage and the second plasma generation stops with a negative voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma generation is continued during substrate attraction and etching, then the substrate can be processed continuously, but particles form on the substrate surface due to by-products and deposits
Solution Approach 1:
The plasma generation process is segmented into distinct phases: first plasma generation during substrate attraction, then cessation of first plasma before second plasma generation for etching. This segmentation prevents particle formation by stopping plasma generation at appropriate intervals while maintaining continuous substrate processing through coordinated phase transitions.
Solution Approach 2:
The plasma generation is applied periodically rather than continuously - first plasma is generated during attraction phase then stopped, followed by second plasma generation during etching phase. This periodic action pattern prevents particle formation while maintaining processing efficiency.
2Stability of the object's composition
If voltage polarity is not reversed, then the electrostatic chuck can maintain stable substrate attraction, but particles of unique polarity form on the substrate surface
Solution Approach 1:
The voltage polarity is inverted between first and second plasma phases - positive voltage during first plasma attraction, then negative voltage during second plasma etching. This inversion prevents formation of particles with specific polarity by alternating the electrostatic field direction, while maintaining stable substrate attraction throughout the process.
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 limits the formation of particles unique to each plasma step, maintaining a cleaner substrate surface by controlling voltage polarity and plasma generation cycles.
Implementation Method 1
a first step of attracting a substrate onto a monopolar electrostatic chuck in a first plasma, which is a plasma of a noble gas
Implementation Method 2
a first plasma generation unit configured to generate a first plasma, which is a plasma of a noble gas, in the chamber
Implementation Method 3
a second step of etching the substrate in a second plasma, which is a plasma of a halogen-based etching gas
Data Source
Figure 1~2
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Figure 5~6
AI summary
A plasma etching method includes a first step of attracting a substrate (S) onto a monopolar electrostatic chuck (15) in a first plasma (PL1), which is a plasma of a noble gas, and stopping generation of the first plasma (PL1) after the attracting of the substrate, and a second step of etching the substrate (S) in a second plasma (PL2), which is a plasma of a halogen-based etching gas, and stopping generation of the second plasma (PL2) after the etching of the substrate. In the first step, the generation of the first plasma (PL1) is stopped when a positive voltage is applied from the monopolar electrostatic chuck (15) to the substrate (S). In the second step, the generation of the second plasma (PL2) is stopped when a negative voltage is applied from the monopolar electrostatic chuck (15) to the substrate (S).