Sputtering Method Impedance Adjusting Circuit Substrate Potential
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Solution Overview
Problem
Existing sputtering methods for depositing piezoelectric films are complex, leading to inconsistent film quality, high production costs, and performance variations due to inadequate control over substrate potential and plasma energy, resulting in compositional offsets and electrostatic breakdown.
Innovation Solution
A sputtering method that uses an impedance adjusting circuit to maintain a predetermined floating potential of the substrate, controlling the plasma energy and substrate potential to prevent back sputtering and ensure high-quality film deposition, specifically by measuring the DC component of the substrate potential and adjusting the impedance to maintain optimal conditions for film deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional sputtering methods with DC or AC power sources are used to apply bias to the substrate, then film deposition can be performed, but the apparatus complexity increases due to additional electrodes and control means
Solution Approach 1:
The invention extracts the bias application function from the substrate electrode and transfers it to the plasma generation electrode. By applying a DC voltage to the plasma generation electrode, the plasma potential is shifted, which automatically applies the necessary bias to the substrate without requiring additional bias electrodes or complex control circuits. This simplifies the apparatus structure while maintaining film deposition quality.
Solution Approach 2:
The plasma generation electrode is given a dual function: it generates plasma through RF power and simultaneously applies bias to the substrate through the applied DC voltage. This eliminates the need for separate bias electrodes and reduces the overall complexity of the sputtering apparatus while maintaining effective substrate biasing for high-quality film deposition.
2Manufacturing precision
If multiple control means are added to adjust substrate potential and plasma energy, then film quality can be improved, but the control system complexity increases
Solution Approach 1:
The invention extracts the plasma energy control function from the complex multi-parameter control system and consolidates it into a single DC voltage parameter applied to the plasma generation electrode. This single parameter controls both the plasma potential and the effective substrate bias, simplifying the control system while maintaining consistent film quality through precise energy control.
3Ease of operation
If DC or AC power sources are used for substrate bias, then substrate potential can be controlled, but positive voltage adjustment is limited
Solution Approach 1:
The invention introduces the plasma generation electrode with applied DC voltage as an intermediary. By controlling the DC voltage on this electrode, the plasma potential is shifted, which in turn controls the effective bias on the substrate. This intermediary approach enables continuous adjustment of substrate potential from negative to positive values, overcoming the limitations of direct DC or AC substrate biasing.
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 results in consistent, high-quality deposition of piezoelectric films with reduced compositional offsets and improved reproducibility, suppressing Pb loss and pyrochlore phase content, suitable for applications in ink-jet heads and other devices.
Implementation Method 1
high-energy Ar ions or other plasma ions that are produced by plasma discharge in high vacuum are allowed to collide with a target, whereupon the constituent elements of the target are released and vapor-deposited on a surface of a substrate
Implementation Method 2
the sputtering method that deposits films by plasma-enhanced vapor-phase growth techniques
Implementation Method 3
a sputtering method comprising determining conditions of film deposition based on a relation among a film deposition temperature, a difference between a plasma potential and a floating potential of the substrate, and characteristics of a film to be deposited
Data Source
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AI summary
The sputtering apparatus includes a vacuum vessel, a sputter electrode placed within the vacuum vessel to hold a target material to be sputtered, a radio frequency power source for applying radio frequency waves to the electrode, a substrate holder which is spaced from the electrode and on which a substrate is held, a thin film being to be deposited on the substrate from components of the target material, and an impedance adjusting circuit for adjusting a first impedance of the substrate holder. The impedance adjusting circuit has a first end directly set at a ground potential and has an impedance circuit which is adjustable for adjusting the first impedance, a second impedance of the impedance circuit is adjusted to thereby adjust the first impedance and, hence, a potential of the substrate.