The Nikkei Asian Review reports that Athene, a Japanese semiconductor technology maker, developed a new shadow mask (or Fine Metal Mask, FMM) specifically for high precision OLED production. The new mask is stronger and more durable than any other mask on the market, which means it can be used to make higher resolution OLEDs.
Samsung AMOLED production
This new strong mask was achieved by adding nickel and iron materials to the standard metal mask. Athene's mask can withstand temperatures of up to 100 degrees Celsius without deformation, and the company says it can enable the production of OLED panels with pixel densities of over 500 PPI. Athene plans to setup a production line to make these new shadow masks and they will start delivering products to OLED makers in 2015.
I'm not sure if a higher PPI is what the OLED industry actually needs. Samsung currently producing 5.1" QHD panels (as used in the Galaxy S5 LTE-A) - the PPI is 577, which is the world's highest density AMOLED (and likely the highest density mobile display altogether). But if this new mask can be made larger compared to current masks, it means that Samsung and other makers may scale-up their OLED production lines to higher substrate sizes, which means higher throughput and lower cost production.
Source: LED Inside
If this fixes the FMM sagging problem, it a pretty big deal for large OLED production. One of the impediments that manufacturers encountered when scaling up OLED fabrication was that the FMM would sag away from the substrate which allow material to deposit underneath the mask. I believe Samsung came up with a method for hanging the mask vertically, but that was not and ideal solution.