Self-aligned imprint lithography, a process developed by HP Labs and PowerFilm Solar for creating thin-film transistor backplanes like those used for flat panel TV monitors, received the Technical Development in Manufacturing award at Printed Electronics 2008.
The award recognizes the most significant development of a manufacturing device, process or production plant in the industry over the last two years. Printed Electronics is Europe's largest conference on printed, thin-film and organic electronics.
Self-aligned imprint lithography, or SAIL, is potentially more efficient and less costly than existing methods of manufacturing thin-film transistor arrays.
Self-aligned imprint lithography
SAIL works by forming thin-film transistor electronics on a flexible substrate that is coated using a roll-to-roll process with all of the thin films required for the devices. The multiple patterns needed to create the backplane are impressed onto different heights of the masking structure. By alternately etching the masking structure and the thin film stack, the patterns are transferred to the device layers.
The current method of creating thin-film transistor arrays relies upon costly photolithography like that used to create most silicon chips. It also requires an expensive aligning process.
SAIL does not need alignment because all of the patterning information is imprinted on the substrate as a single three-dimensional masking structure, which moves with the substrate, perfect alignment is maintained regardless of process induced distortion.
Eliminating both photolithography and the alignment process could significantly reduce the cost of active matrix backplane manufacturing.
Achieving a first
HP Labs developed an imprinting method that maintains fidelity through the thousands of impressions required to process a roll of plastic substrate that is 1km long. By comparison, other imprinting processes use stamp materials that fail after only a few tens of cycles due to swelling and eventual fracture. HP Labs has demonstrated the fabrication of 40nm wide lines on 50u thick plastic substrates with the process.
Carl Taussig, director of HP Labs' Information Surfaces Lab accepted the award at the conference in Dresden, Germany.
HP Labs and PowerFilm Solar are the first to demonstrate fabrication of an amorphous silicon thin-film transistor array with a fully roll-to-roll process. The team has leveraged the equipment and expertise from PowerFilm's 20 years of experience making solar cells on plastic substrates with a completely roll-to-roll process.