Roll-to-roll processing, also known as 'web' processing, is the process of creating electronic devices on a roll of flexible plastic or metal foil. Large circuits made with thin-film transistors and other devices can be easily patterned onto these large substrates, which can be up to a few metres wide and 50 km long. Some of the devices can be patterned directly, much like an ink jet printer deposits ink. For most semiconductors, however, the devices must be patterened using photolithography techniques.

Roll-to-roll processing is a technology which is still in development. If semiconductor devices can be fabricated in this way on large substrates, many devices could be fabricated at a fraction of the cost of traditional semiconductor manufacturing methods. Most notable would be solar cells, which are still prohibitively expensive for most markets due to the high cost per unit area of traditional crystalline silicon manufacturing. Other applications could arise which take advantage of the flexible nature of the substrates, such as electronics embedded into clothing, large-area flexible displays, and roll-up portable displays.

Related:
Thin-film transistor
Amorphous silicon