Classification Of Bias Voltage in Coating Process

Classification of bias voltage in coating process:

1, dc negative bias
The positive ions in the plasma can obtain more energy by loading negative dc bias voltage on the workpiece. The positive ions can accelerate the bombardment of the workpiece and guide the deposition of the charged ions splashed from the surface of the target to some extent. Dc negative bias is continuous without interruption, so it has a certain heating effect on the substrate.
2, dc positive bias
In the gas discharge of ion plating, the gas nucleated particles show a certain negative potential. In this case, the workpiece is loaded with a certain positive bias, which is beneficial to film deposition.
3. Pulse bias
Oscillating plasma. The density and temperature of plasma can be increased by decreasing the pulse duty ratio and increasing the intensity of pulse power supply. Bombardment effect is improved on all types of substrates (conductive & non-conductive). As a result, the survival time of secondary electrons increases, the collision probability increases, and the plasma density increases. The deposition rate can be controlled by adjusting pulse frequency and duty cycle. Temperature rise can be controlled by adjusting pulse frequency and duty cycle, and film can be formed at low temperature to avoid damage to the original tissue of the substrate. For multiple arcs, the deposition rate is too fast, so it is not suitable for the film deposition of electronic devices and other precision workpiece. The introduction of pulse bias can be effectively improved.
4, zero bias and suspension bias
In the coating process without charged particles (such as simple evaporation, etc.), zero bias/suspension bias can be used.
Tolerance of low temperature workpiece (such as plastic parts, etc.) coating, in order to prevent workpiece deformation, can choose zero bias/suspension bias or select small duty cycle low amplitude bias voltage.

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