Reactive Sputtering Voltage Control for Stable Film Formation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Reactive sputtering processes face instability due to rapid transitions between metal and poisoning modes, making it difficult to achieve high-speed, stable film formation, especially in large chambers with multiple substrates, where controlling the reaction gas partial pressure and plasma emission is challenging.
Innovation Solution
A method combining constant-voltage control for stabilizing the sputtering process with target voltage control based on plasma emission spectra to maintain the transition mode, using two control systems with different feedback speeds to prevent interference and ensure stable film formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the reaction gas partial pressure is increased to form a compound coating on the substrate, then the compound film formation is achieved, but the film formation speed is significantly reduced due to target poisoning
Solution Approach 1:
The patent applies dynamics by making the sputtering voltage variable rather than constant. The control unit dynamically adjusts the sputtering voltage based on real-time monitoring of reaction gas partial pressure and plasma emission intensity, allowing the system to transition between metal mode and compound mode as needed. This dynamic control enables the target surface composition to be optimized continuously, maintaining high film formation speed while achieving desired compound film composition.
Solution Approach 2:
The patent changes the sputtering voltage parameter in response to changes in reaction gas partial pressure and plasma emission characteristics. By monitoring the plasma emission intensity and adjusting the voltage accordingly, the system maintains optimal conditions for compound film formation. This parameter change strategy allows the process to operate in the transition mode where both high deposition rate and compound formation are achieved.
2Stability of the object's composition
If the reaction gas flow rate is increased to achieve stable compound film formation, then the film composition is controlled, but the process becomes unstable due to rapid transitions between metal and poisoning modes
Solution Approach 1:
The patent implements feedback control by monitoring plasma emission intensity and using this information to adjust the sputtering voltage. The control unit continuously compares the actual plasma emission with target values and modifies the voltage to maintain stable operation in the transition mode. This feedback mechanism prevents rapid transitions between metal and poisoning modes, ensuring both composition stability and process reliability.
Solution Approach 2:
The patent replaces mechanical control of gas flow rates with electromagnetic control of sputtering voltage. Instead of mechanically adjusting gas valves to control the transition between modes, the system uses electromagnetic fields (sputtering voltage) to control the target surface composition. This substitution allows for more precise and rapid control, improving both stability and reliability.
3Reliability
If constant voltage control is used to stabilize the sputtering process, then the process stability is improved, but the film formation mode cannot be maintained under varying process conditions
Solution Approach 1:
The patent makes the sputtering voltage dynamic rather than constant. The control unit adjusts the voltage in real-time based on plasma emission monitoring, allowing the system to adapt to changing process conditions such as reaction gas flow rate variations and residual gas effects. This dynamic approach maintains both stability and adaptability simultaneously.
Solution Approach 2:
The patent changes the sputtering voltage parameter in response to plasma emission intensity changes. By monitoring the plasma emission spectrum and adjusting the voltage accordingly, the system maintains optimal operating conditions even when external parameters like gas flow rates change. This parameter adaptation ensures the film formation mode remains stable under varying process conditions.
4Productivity
If the sputtering power is increased to achieve high-speed film formation, then the productivity is improved, but the target surface becomes poisoned and the film formation speed decreases
Solution Approach 1:
The patent changes the sputtering voltage parameter dynamically based on plasma emission monitoring. When the target surface begins to poison (indicated by plasma emission changes), the system adjusts the voltage to restore optimal sputtering conditions. This parameter adjustment maintains high film formation speed while preventing target poisoning, ensuring both productivity and composition control.
Solution Approach 2:
The patent implements feedback control where plasma emission intensity is monitored and used to adjust the sputtering power. This feedback mechanism prevents target poisoning by detecting early signs of compound formation on the target surface and adjusting the power accordingly. The result is sustained high-speed film formation with maintained composition control.
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 allows for stable and high-speed film formation in the transition mode, maintaining the desired film formation mode regardless of process conditions, such as reaction gas flow rates and residual gases, thereby improving the consistency and quality of compound films.
Implementation Method 1
a sputtering vaporization source provided with a metal target; sputtering vaporization is performed by a sputtering vaporization source, and thereby a compound coating of the metal and the reaction gas is formed on a substrate
Implementation Method 2
detecting plasma emission generated forward of the sputtering vaporization source; operating the target voltage Vs in order that a spectrum of the plasma emission becomes a target value
Data Source
AI summary
The present invention provides a method for reactive sputtering in which a reactive sputtering apparatus including a sputtering vaporization source 2 provided with a metal target disposed in a vacuum chamber 1, a sputtering power source 4 to drive the sputtering vaporization source 2, and an introduction mechanism 5 to introduce an inert gas for sputtering and a reaction gas for forming a compound with sputtered metal into the vacuum chamber 1 is used, and reactive sputtering film formation is performed on a substrate 3 disposed in the above-described vacuum chamber, wherein the method includes the steps of performing constant-voltage control to control the voltage of the above-described sputtering power source 4 at a target voltage Vs and, in addition, performing target voltage control at a control speed lower than the speed of the above-described constant-voltage control, the target voltage control operating the above-described target voltage Vs in order that the spectrum of plasma emission generated forward of the above-described sputtering vaporization source 2 becomes a target value.