Low voltage sputtering preparation
ITO filmDue to the presence of oxygen elements in ITO films, a large amount of oxygen negative ions are generated during the magnetron sputtering process. Under the action of an electric field, oxygen negative ions will bombard the surface of the deposited ITO film with a certain amount of particle energy, causing structural defects in the crystalline structure and crystal state of the ITO film.
The higher the sputtering voltage, the greater the energy of oxygen negative ions bombarding the surface of the film layer, resulting in a higher probability of causing structural defects and more severe crystal structure defects, leading to an increase in the resistivity of the ITO film.
In general, the sputtering voltage for magnetron sputtering deposition of ITO film is around -400V. If a certain process method is used to reduce the sputtering voltage to below -200V, the resistivity of the deposited ITO film will be reduced by more than 50%. This not only improves the product quality of ITO film, but also reduces the production cost of the product.
Two effective ways to reduce the sputtering voltage of ITO thin films prepared by DC magnetron sputtering: the influence of magnetic field strength on sputtering voltage. When the magnetic field strength is 300G, the sputtering voltage is about -350V; But when the magnetic field strength increases to 1000G, the sputtering voltage drops to around -250V.
In general, the higher the magnetic field strength, the lower the sputtering voltage, but when the magnetic field strength is above 1000G, the effect of magnetic field strength on sputtering voltage is not significant. Therefore, in order to reduce the sputtering voltage of ITO thin films, it can be achieved by reasonably enhancing the magnetic field strength of the sputtering cathode.
In order to effectively reduce the voltage of magnetron sputtering and achieve the goal of reducing the resistivity of ITO thin films, a special sputtering cathode structure and sputtering DC power supply can be used. At the same time, a 3KW RF power supply can be reasonably matched and stacked on a 6KW DC power supply to study the process of reducing the sputtering voltage of ITO thin films under different DC sputtering power and RF power.
When the magnetic field strength is 1000G and the power of the DC power supply is 1200W, by changing the power of the RF power supply, a large number of process experiments have concluded that "when the RF power is 600W, the sputtering voltage of the ITO target can be reduced to -110V". Therefore, the application of new RF DC power supplies and the design of special sputtering cathode structures can effectively reduce the sputtering voltage of ITO films, thereby achieving the goal of reducing film resistivity.
reduce
ITO filmThe new deposition method of resistivity, HDAP method, uses high-density arc plasma (HDAP) discharge to bombard ITO target material, causing ITO material to evaporate and deposit onto the substrate material to form ITO thin film. Due to the action of high-energy arc ions, In and Sn in ITO particles are completely ionized, thereby enhancing the reaction activity during deposition, reducing crystal structure defects, and lowering electrical resistivity.
Using ITO materials with the same composition and keeping other process conditions the same, experiments were conducted on "DC magnetron sputtering", "DC RF magnetron sputtering", and "HDAP method for preparing ITO thin films" at the same substrate temperature.
The experimental results show that using HDAP method can obtain ITO thin films with lower resistivity, especially when preparing ITO thin films on materials with substrate temperatures that cannot be too high. Using HDAP method to prepare ITO thin films can obtain ideal ITO thin films. When the substrate temperature reaches around 350 ℃, these three deposition methods have little effect on the resistivity of ITO thin films.
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