Vitex provides "secret sauce" for Europe's first volume P-OLED producer, MED

Sept. 7, 2007
MicroEmissive Displays has commercialized top-emissive polymer OLED displays thanks to its relationship with Vitex, writes Tom Cheyney of Small Times.
With its recent move into production and commercial shipment of its top-emissive, polymer-based organic light-emitting diode (P-OLED) microdisplays, Edinburgh, Scotland-based MicroEmissive Displays (MED) has become the first European company to manufacture such devices at volume levels.

One critical component of MED's Dresden factory ramp-up is the licensing and materials supply deal that it signed in May with Vitex Systems Inc. and its tool partner, ANS Korea.

"The introduction of the Barix process into our manufacturing process will result in significant improvements to the quality and reliability of our next-generation displays," explained John McEachran, MED's director of operations. "The leading-edge encapsulation technology from Vitex and excellent support surrounding ANS's production equipment enabled us to meet our aggressive production ramp goals."

On July 24, 2007 CEO Bill Miller said that the first batch of MED's eyescreen ME3204 full-color microdisplays shipped on schedule from the purpose-built Dresden cleanroom facility, six months after the company began qualifying and commissioning the site. Although he declined to provide further details of MED's process, fab capacity, and current or projected shipment volumes, Miller did note that ANS supplied both P-OLED deposition equipment and the encapsulation system as parts of its "volume manufacturing toolset."

MED's Website describes a multilayer thin-film deposition process (reported elsewhere to be spin-coating) on custom mirrored CMOS wafers (fabbed by foundry partner UMC), which act as active-matrix backplanes. While Miller would not disclose any film thickness data, one deposited "nanolayer" is a light-emitting P-OLED material.

Mark Hartney, CTO of the U.S. Display Consortium, sees MED's ramp to volume production as "a positive step, since there has been limited production for P-OLEDs in the past." He also notes the importance of Vitex's Barix moisture and oxygen barrier films. "A key to lifetime and device performance is the encapsulation technology that Vitex's Barix provides. This [technology] is such a critical step, not only in P-OLED, but for many of the flexible and organic electronics efforts that are starting up."

One major challenge that Barix faced in integrating into the MED production process is "the small [0. 5 mm] edge-seal space available," explains Vitex's director of marketing, Chyi-Shan Suen. "Because one wishes to maximize the number of displays on the CMOS wafer, we developed a very narrow edge-seal process. This is narrower than the best OLED and LCD edge, which is about 1.5 mm. This also required the mask alignment mechanism to be modified, [which] is an intrinsic advantage of thin-film encapsulation."

Another difficult part of Vitex and ANS's task at MED was the "machine design and process integration," says Suen. "Although we sometimes use silicon wafers as testing vehicles, this is the first time we applied thin-film encapsulation on silicon wafers in a production environment. The display size was also very different from what we had been dealing with in the past." MED's eyescreen products have 76,800 pixels on a 6-mm diagonal chip and are used for electronic viewfinders, head-mounted displays, gaming consoles, and mobile phone screens.

Hartney believes that Sumitomo Chemical's recent acquisition of Cambridge Display Technology (see news), the industry pioneer that licenses its proprietary P-OLED technology to MED, "will strengthen the CDT technology, as it provides a lot more patient capital behind [it]. They had an ongoing relationship and already had [the Sumation] joint venture for materials production, so there has been a strong sentiment for support from Sumitomo already." For its part, MED does "not expect to see any change in the relationship with CDT," according to Miller.