Sputtering Deposition Rate of Different Targets Under Different Conditions

Sputtering Deposition Rate of Different Targets Under Different Conditions

(Based on the application of SD-900M low vacuum magnetron sputtering coater)

In the field of modern material science and surface engineering, magnetron sputtering technology has become an indispensable process method because of its excellent performance in thin film deposition. Sputtering technology is widely used in semiconductor, optics, memory and decorative coating fields. As a key variable affecting the quality, thickness uniformity and performance of the film, the sputtering rate is affected by many factors, including target type, vacuum degree, working gas pressure, power supply, magnetic field strength and so on. A thorough understanding of the influence of these factors on the sputtering rate is of great significance for optimizing the process parameters and improving the quality of the film.

This paper will discuss the sputtering rate of different targets under different conditions, combined with the practical application of VPI (Vision Precision Instruments) SD-900M model low vacuum magnetron sputtering coater, to provide reference for researchers and engineers.

1. The influence of target type on sputtering rate

1.    Physical and chemical properties of the target

   The sputtering rate of the target is mainly affected by its physical and chemical properties, and key factors include:

   - Atomic Mass: Elements with larger atomic weight have larger atomic momentum and are more likely to be knocked out by particles with higher energy during sputtering.

   - Binding Energy: The lower the surface binding energy of the material, the easier it is for the atom to escape from the surface and the higher the sputtering rate.

   - Surface Atom Density: A high surface atom density means that more atoms are available for sputtering, thus increasing the sputtering rate.

   For example: Copper (Cu) has an atomic weight of 63.55 u and a binding energy of about 3.5 eV, while carbon (C) has an atomic weight of 12.01 u and a binding energy of about 7.4 eV. Therefore: under the same conditions, the sputtering rate of copper is much higher than carbon.

2 Purity and microstructure of the target material

   - Purity: A high purity target can provide a more stable sputtering environment. The presence of impurities may lead to the production of non-uniform plasma during sputtering, affecting the sputtering rate and film quality.

   - Crystal structure: The crystal structure of a single crystal, polycrystalline or amorphous target can affect the directivity and energy distribution of sputtered atoms, which in turn affects the sputtering rate.

3. Alloys and composite targets

   For alloys or composite targets, the sputtering rate is also affected by the sputtering yield of each component element. The different sputtering yield of different elements may lead to segregation of components, which needs to be adjusted in the process parameters.

Second, the influence of sputtering conditions on the sputtering rate

1. Vacuum and working gas pressure

   - Vacuum degree: The high vacuum environment is conducive to reducing the influence of impurity gas and ensuring the purity of the sputtering process.

   - Working gas pressure: usually use inert gas such as argon. Gas pressure affects the density and energy distribution of the plasma. Proper pressure helps to form a stable plasma and increase the sputtering rate.

2 Supply power and voltage

   - Power: Increasing the power supply can increase the density and energy of the plasma and enhance the sputtering effect.

   - Voltage: High voltage helps to accelerate electrons and ions, improve the energy of bombarding the target, and thus improve the sputtering rate.

3. Magnetic field strength and configuration

   - Magnetic field strength: Magnetic fields are used to bind electrons and improve plasma density. Appropriate magnetic field strength can improve sputtering efficiency.

   - Magnetic field configuration: Different magnetic field configurations (such as flat, cylindrical) will affect the magnetic field distribution, which will affect the sputtering area and rate.

4. Target base distance and substrate temperature

   - Target base distance: The distance between the target and the substrate will affect the probability and energy of the sputtered atoms reaching the substrate.

   - Substrate temperature: Substrate temperature will affect the growth pattern and crystallization quality of the film, indirectly affecting the effective utilization of the sputtering rate.