Plasma Chamber Power Control to Reduce Substrate Crazing
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Solution Overview
Problem
Crazing defects occur in large-area sputtering processes, particularly in AC power-supplied systems, leading to substrate damage, and existing methods are limited in preventing or mitigating these defects, especially as glass thickness increases.
Innovation Solution
A method involving real-time monitoring of plasma processing parameters within a plasma chamber, where a power supply signal is adjusted to modify specific features related to the monitored parameters, such as voltage, current, or power, to reduce the occurrence of crazing, using a current-controlled signal and bipolar power supply, with the goal of maintaining the substrate on a floating potential.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If AC power supply is used in large-area sputtering process, then productivity is improved, but crazing defects occur on substrate
Solution Approach 1:
The patent applies periodic action by using pulsed DC power supply instead of continuous AC power supply. The power is supplied in periodic pulses with controlled duty cycle, allowing the plasma process to proceed productively during pulse-on periods while preventing continuous ion bombardment that causes crazing during pulse-off periods. This periodic modulation resolves the contradiction between maintaining high deposition rates and preventing substrate damage.
Solution Approach 2:
The patent changes the power supply parameters from AC waveform to pulsed DC waveform, controlling parameters such as pulse width, duty cycle, and peak power. By dynamically adjusting these parameters, the system maintains high productivity during active deposition while reducing ion bombardment intensity to prevent crazing, thus resolving the technical contradiction between output and quality.
2Strength
If glass thickness is increased, then substrate strength is improved, but crazing prevention becomes more difficult
Solution Approach 1:
For thicker glass substrates which are more susceptible to crazing, the patent employs periodic pulsed power supply with optimized duty cycles. The periodic interruption of ion bombardment allows stress relaxation in the thicker glass structure, preventing cumulative damage that would lead to crazing, while maintaining adequate deposition rates during active pulses.
Solution Approach 2:
The patent applies preliminary action by using edge rounding of the glass substrate before deposition. This pre-treatment modifies the stress distribution at the glass edges, which are critical points for crazing initiation. Combined with pulsed power supply, this preliminary structural modification enables successful processing of thicker glass without crazing defects.
3Object-affected harmful factors
If power supply signal is adjusted in real-time, then crazing is reduced, but system complexity increases
Solution Approach 1:
The patent implements feedback control by monitoring plasma parameters (such as voltage, current, or optical emission) in real-time and using this information to dynamically adjust the pulsed power supply signal. This closed-loop feedback system automatically optimizes the deposition process and prevents crazing by detecting and responding to adverse conditions, resolving the contradiction between quality improvement and system complexity through intelligent automation.
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 approach effectively minimizes the formation of crazing on substrates by actively adjusting power supply signals during plasma processing, reducing the probability of crazing and maintaining the substrate's integrity, even with thicker glass, by continuously adapting to changes in the plasma chamber conditions.
Implementation Method 1
supplying a power supply signal to electrodes arranged within the plasma chamber in order to form a plasma in the plasma chamber
Data Source
AI summary
A method of plasma processing a substrate in a plasma chamber is provided. The method includes the steps of supplying a power supply signal to electrodes arranged within the plasma chamber in order to form a plasma in the plasma chamber, monitoring at least one parameter related to the plasma processing, determining a feature related to the at least one monitored parameter, and adjusting the power supply signal during the plasma processing to modify, in particular reduce, the feature. The modification of the feature eliminates or mitigates formation of crazing on the substrate.