Substrate Charge Control via Self-Bias Feedback in Plasma Processing
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Solution Overview
Problem
In high-power and low-temperature film formation processes, silicon substrates tend to stick to the susceptor due to electrostatic attraction, leading to substrate transfer errors or damage, necessitating effective static electricity removal based on varying plasma processing conditions.
Innovation Solution
A substrate processing method involving plasma processing with an RF electrode, where power is applied for a predetermined static electricity removal time to reduce substrate charge, and the self-bias voltage is monitored to adjust the removal time, ensuring the substrate is lifted safely without sticking, by shortening the time for positive self-bias voltage and lengthening it for negative values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If plasma processing is performed with RF power for film formation, then film formation is achieved, but the substrate becomes charged with electrical charges causing it to stick to the susceptor
Solution Approach 1:
The patent utilizes the plasma processing mechanism itself to remove static electricity from the substrate. By controlling RF power application during a post-treatment phase, the plasma discharge neutralizes accumulated charges on the substrate surface, converting the harmful electrostatic effect into a beneficial self-cleaning process without requiring additional equipment or complex procedures
2Ease of operation
If susceptor pins are used to lift the substrate from the susceptor, then substrate transfer is enabled, but great force acts on the substrate causing transfer errors or damage
Solution Approach 1:
The patent applies plasma processing before substrate transfer to preemptively remove electrostatic charges that would cause sticking. By eliminating the electrostatic attraction in advance, the substrate can be lifted by susceptor pins without requiring excessive force, thereby preventing mechanical damage and transfer errors before they occur
3Object-generated harmful factors
If static electricity removal time is increased to reduce substrate charge, then sticking is suppressed, but processing time increases
Solution Approach 1:
The patent implements a feedback control mechanism where RF power is applied intermittently during plasma processing, with the duration and intensity adjusted based on real-time monitoring of processing conditions. This adaptive approach optimizes static electricity removal efficiency while minimizing unnecessary processing time, achieving charge reduction without excessive time expenditure
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 reduces substrate charge, preventing sticking and ensuring accurate transfer by optimizing the static electricity removal time based on real-time self-bias voltage measurements, thereby minimizing substrate damage and transfer errors.
Implementation Method 1
applying power to an RF electrode facing the susceptor for only a predetermined static electricity removal time to generate plasma
Implementation Method 2
applying power to an RF electrode facing the susceptor for only a predetermined static electricity removal time to generate plasma
Implementation Method 3
a Si substrate is charged with electrical charges, so that the susceptor and the Si substrate electrostatically attract each other and stick to each other
Data Source
AI summary
Examples of a substrate processing method include subjecting a substrate placed on a susceptor to plasma processing, applying power to an RF electrode facing the susceptor for only a predetermined static electricity removal time to generate plasma, thereby reducing an amount of charge of the substrate, measuring a self-bias voltage of the RF electrode while susceptor pins are made to protrude from a top surface of the susceptor and lift up the substrate, and by a controller, shortening the static electricity removal time when the self-bias voltage has a positive value, and lengthening the static electricity removal time when the self-bias voltage has a negative value.