ITO Coatings

THE HEX SERIES

Indium Tin Oxide

Many day-to-day items rely on transparent, conductive coatings to operate from windshields to touch screens. Glass in its pure form is not a great conductor or either heat or electricity and so for certain applications – a thin layer of material is needed to improve this, while maintaining the transparent nature of the substrate.

Indium Tin Oxide (ITO) Coatings can be used in these cases and are regularly used in various fields. It can greatly alter the properties of glass, mylar or other transparent substrates when deposited as a thin film with its main benefits being the improvement of the conductivity and the refractive index of the deposited upon glass.

The thickness of the coating can vary depending on the application, with a thicker ITO layer offering a greater conductance, but increasing its opacity. They can also prove to be very stable under heat loads of below 150C.

Another key aspect of an ITO coating is its resistance to electromagnetic wave penetration; therefore, ITO coated substrates can be key features of windows that require EM radiation protection but must retain its transparency.

ITO films can be deposited onto substrates via CVD, ink polymer-resin processes and most commonly through PVD. Korvus Technology has over 20 years of experience working within the PVD field and is the manufacturer of the HEX series of PVD instruments. These tools can be configured to allow for the optimized deposition of ITO coatings through DC magnetron sputtering and E-Beam evaporation.

Due to the conductive nature of ITO material, DC magnetron sputtering processes can be used to achieve high levels of uniformity across various wafer and substrate sizes. We recommend using the Korvus-custom tiltable FISSION 3’’ magnetrons to curate a balance between uniformity, target usage and deposition rate suitable to your process. Altering the source to sample distance is also crucial for ITO deposition to control the electron interactions between the generated plasma and the sample.

Frequently Asked Questions

ITO coatings in PVD refer to thin films of Indium Tin Oxide (ITO) deposited using Physical Vapor Deposition techniques. ITO is a transparent conducting oxide (TCO), meaning it’s optically transparent and electrically conductive—a rare and extremely useful combination. It’s widely used in applications where light needs to pass through a conductive surface.

  • Touchscreens and smartphone displays

  • Flat panel displays (LCD, OLED, LED)

  • Solar cells (especially perovskite and organic photovoltaics)

  • Smart windows and electrochromic devices

  • Light-emitting diodes (LEDs)

  • Thin-film transistors and sensors

  • Typically 90% Indium Oxide (In₂O₃) + 10% Tin Oxide (SnO₂) (by weight)

  • This specific ratio balances:

    • High electrical conductivity

    • High optical transparency (especially in visible light)

    • Good adhesion and durability

There are several PVD methods to create ITO coatings:

1. RF or DC Magnetron Sputtering (most common)

  • Target: Pre-made ITO ceramic target

  • Process: Argon gas bombards the target, sputtering ITO atoms which deposit onto the substrate

  • Reactive mode (e.g., with O₂) can be used to tune stoichiometry

  • Can be done at room temp or elevated temp (~200–400 °C) for better crystallinity

2. Thermal or Electron Beam (E-Beam) Evaporation

  • Less common for ITO due to its high melting point and complex composition

  • Needs special care to avoid phase separation of In and Sn during deposition

  • Often followed by post-deposition annealing to improve conductivity and transparency

ITO properties can be optimized by adjusting:

  • Oxygen partial pressure during sputtering (too little = poor transparency; too much = poor conductivity)

  • Substrate temperature

  • Post-deposition annealing

  • Film thickness and deposition rate

This balance is critical depending on the application:

  • Solar cells: Maximize transparency and minimize resistive losses

  • Touchscreens: Prioritize conductivity and uniformity

  • Flexible electronics: Need good adhesion and possibly low-temp processing

In perovskite solar cell research, ITO is commonly used as the bottom electrode because it’s:

  • Transparent (lets light in)

  • Conductive (collects or injects charge)

  • Compatible with PVD and spin-coating processes