Samsung's in-house display manufacturing outfit, the aptly named Samsung Display, makes use of photomasks in much the same way as any other manufacturer. Photomasks are essentially light-based die casts on a substrate made of glass or some other material that allow a machine to cut, decorate and otherwise manufacture a printed circuit board. While there are other uses for photomasks, this is the most prominent use and the one that Samsung Display engages in, the only use of the devices that they happen to engage in for now. That could change in the near future, however, as they plan to begin manufacturing their own photomasks and using them in-house. While this may cause a bit of extra stress on their assembly lines and equipment in the short term, there are a number of reasons why this is a good move.
For starters, although getting the equipment set up initially will be a bit of a financial burden, making their own photomasks instead of commissioning them from contractors will save Samsung Display a good amount of money in the long run. Once the equipment is set up, it's a relatively simple matter to take a design, impose it onto a photomask and implement the photomask into the PCB manufacturing process. While they will obviously need to devote employee time to design and manufacture of the photomasks, as well as pay for materials, they will essentially be free otherwise. Naturally, this also means that Samsung Display may be able to make some side cash taking on contracts to manufacture photomasks for others in the future.
The other advantage of Samsung Display manufacturing their own photomasks is acute control over the entire process. Although they can design a photomask and send it to a manufacturer along with a spec sheet, they have no control over how the manufacturer will approach making it. Additionally, most contracting manufacturers will not be willing to take on some of the more outlandish and innovative designs that could give Samsung an edge by making their manufacturing easier and more efficient, or by allowing them to create more advanced PCBs. With Samsung Display taking on responsibility for making their own photomasks, all of these possibilities are open.