Ultra High Definition Flat Panel Display Sputtering Targets

Interview conducted by G.P. ThomasSep 18 2013

Harald Selb, Head of Market Unit Display and Solar at PLANSEE, talks to AZoM about the need for high purity in sputtering target materials for ultra-high definition flat panel displays, as well as solar and touch panels.

Could you please provide an introduction to Plansee and the sectors that it works within?

Plansee High Performance Materials are experts in the manufacturing of components, mainly out of molybdenum, tungsten, tantalum, niobium and chromium which are refractory metals.

We are the number one supplier into the market for refractory metals and we also produce alloys and composite materials made out of these refractory metals.

We supply different markets, including the display industry, solar industry, electronics industry and medical industry.

A big portion of our market is the creation of sputtering targets for display and solar applications. For example, we supply molybdenum based or tungsten based pure material sputtering targets for thin film transistors in common displays.

Plansee was founded more than 90 years ago; therefore we have accumulated much expertise and knowledge, particularly in how to treat materials in terms of our manufacturing capabilities.

You mentioned sputtering targets - could you briefly explain what a sputtering target is and how they work within a display screen?

These flat panel displays are made out of several very thin layers which are deposited onto a glass substrate.

Some of these layers control a pixel in the screen, which determines what color it glows. To control these pixels thin-film transistors are required to control the final color of the picture.

You also need some conductive layers, as well as several thin-film layers, among which molybdenum thin films are being used.

We supply these sputtering targets, which are used in sputtering equipment. These ‘sputter’ off molybdenum particles, which then start to grow on the substrate material, eventually generating the very thin layers.

PLANSEE bonded planar sputtering target. Image Credit: Plansee High Performance Materials  

What are the main challenges for Plansee when creating materials for this technology?

The technology in general for the flat panel display industry has seen big growth in the past few years - screens are getting bigger, resolution is continually increasing, currently we're talking about HD displays but the next generation will be the ultra-high definition (UHD or 4Kx2K)) displays.

So for HD and ultra HD screens the best quality is required for these materials which get sputtered into the thin-film layers.

In terms of purity, it is very important that the materials used for the UHD technology has maximum purity. This is the main challenge, to provide sputtering targets with maximum optimized purity and at Plansee, we can supply this for both existing technologies and for the upcoming UHD technology.

Why is material purity so important for creating UHD screens?

It is very important because in ultra-high definition, the resolution of this technology is four times higher than the common HD and you can imagine that even small impurities, or as we call them particles, can have a significant negative influence on the conductivity of the molybdenum layers for example.

If the conductivity of these very thin layers is not sufficiently optimized, then pixels will fail, and at this high of a resolution any lack of available pixels will have considerable impact on the quality of the display itself as well as the picture it displays. That is why it is important to have maximum purity.

What production process does Plansee use to achieve such high purities?

Plansee is the only player in this market, or in the entire refractory metal industry, that has the entire manufacturing chain controlled and maintained in-house.

We start with the raw ore such as either molybdenum or tungsten ore. For example, from the molybdenum ore, we obtain molybdenum trioxide powder which through some of our in-house processes we convert into pure molybdenum.

The first thing that we do is clean the material at high temperatures and our in-house process cleans it multiple times in the purification process. Some of the processing involves pressing and sintering, which also cleans the material.

After pressing, we perform various deformation processes. This material already shows the high purity that Plansee guarantees, which is 99.97% for molybdenum and tungsten.

Then, based on the final shapes of targets or any other products which we supply to the different markets, final machining is all done in-house as well as any bonding of the targets made of molybdenum, tungsten or alloy materials onto backing tubes and plates.

We control this entirely in-house, therefore we have our own bonding shops located in Asia in several countries where we again ensure that the material does not gain any kind of impurity during this process.

This makes us a unique player as we control the entire process from the ore to the finish bond of the target, ensuring the quality of the product and guaranteeing 99.97% purity.

What else does Plansee provide to the display manufacturers apart from the sputtering targets?

Our focus of course is on the sputtering target materials, but besides our core materials (molybdenum and tungsten) we also supply other materials like copper, titanium or aluminum.

These materials are also widely used in the display industry. Our customers run different processes and utilize different equipment and depending on their technology we offer different materials in a broad range to support them.

We want to supply packages that support our customer’s entire process and to help them develop and diversify into new technologies. We are able to provide materials as either planar targets or as rotary targets - there's a strong trend that is continuously growing in the display industry for rotary targets.

Rotary Target Inspection at PLANSEE bonding shop in Korea. Image Credit: Plansee High Performance Materials  

Could we briefly talk about the other areas of industry that sputtering targets are used in, such as solar and touch panels?

These are also very important markets for us, and the requirements and specifications are similar.

Solar is still very important to us, but the touch panel industry is also becoming very important as it is a rapidly growing market.

The same is valid is the microelectronics industry, which requires the use of many tungsten or chromium targets, as well targets to enhance the wear resistance of tools which are then used for machining.

How do you see the thin film industry progressing over the next ten years and how will Plansee be a part of that?

In the past the flat panel display industry was always heavily driven by TVs, but now more and more mobile applications are growing as indicated using both small and mid-size panels. So there is definitely room to grow with smart phones and tablets in the future and this will drive the market in the next five years.

In the next ten years, this will growth will definitely continue, new applications will arise and we are definitely prepared to follow all these different moves and trends and we will stay close to our customers to understand their needs, how they are developing, and to support the constant changes in technologies.

Lastly, where can people find more information about Plansee?

We have very detailed information about our materials, specifically on planar or rotary sputtering targets on our website.

There you can also find a lot of technical information about our materials, especially molybdenum and tungsten.

About Harald Selb

Harald Selb is Head of Market Unit Display and Solar at PLANSEE SE. In his current role, he is responsible for the global Sales and Marketing of PLANSEE´s broad range of Sputtering Targets for the applications Display and Solar.

After 10 years working in the optical media industry he joined PLANSEE 2008 as Customer Group Manager for applications Single Crystal Growing and Epitaxial Growth (MBE/MOCVD).

He holds an engineering degree in electronics from the Higher Technical College for Telecommunication & Engineering in Innsbruck, Austria.