Cutting-edge Semiconductor Production

Printed semiconductors are designed using the same electronic design automation (EDA) tools used for traditional integrated circuits. The finished layout is then translated into files the printer can read.

It is essential that the functional materials and substrates have the right composition and properties. NANOIDENT follows a rigorous incoming inspection process, where all materials are subjected to a variety of sophisticated chemical, electrical, optical, and mechanical tests.

The materials to be printed - conducting, semiconducting, etc. - consist of conjugated polymers and/or nanoparticles in solvents, which must be specially formulated for use in industrial printing systems, such as screen-printers, offset-printers, or inkjet printers. It is important that the viscosity is correctly adjusted to the printing technique - for instance, with inkjet the "ink" must be thin enough to pass through the tiny nozzles on an inkjet print head, but thick enough that the correct amount is deposited. Additives may be required to ensure uniform layers or to adjust drying times. The material is then tested to ensure properties such as surface tension, viscosity, and chemical structure meet very narrow specifications.

Printed semiconductors can be printed on a wide variety of substrates, including glass, plastic, or ceramic. The material can be rigid or flexible, flat or curved, thick or as thin as 20 micrometers. Before printing, the substrate must be cleaned and treated to ensure proper surface properties.

Printing is done one layer and one "ink" at a time (semiconductor, conductor, insulator, resistor, and dielectric), each deposited using industrial printing systems such as inkjet printers. With typical layer thickness between 20 - 200 nanometers and feature sizes as small as 10 micrometers, a great degree of accuracy is required. The layers must align precisely for the device to function properly. To achieve this, the substrate is mounted on a computer-controlled X-Y table, a precision instrument with high-speed linear motors enabling precise control of movement with sub-micrometer accuracy.

Quality assurance occurs as each layer is printed, using a machine vision system. A high-speed camera detects layer alignment, and the volume, thickness, and position of every drop in every structure of each device; this information is computer-analyzed, and defective components are immediately recognized and discarded.

Each layer must be dry before subsequent layers are printed. To speed drying time and improve electrical properties, each layer is specially cured. Curing temperature must be tightly controlled--high enough to treat the printed material, but not so high as to damage the substrate or previously printed layers.

Just as in a silicon fab, many devices may be printed on one substrate. Once all layers have been printed and cured, a computer-controlled laser or glass dicing system precisely cuts the individual pieces apart. All devices then go through an automated electrical/optical test.

If needed, other components can be attached to the substrate, such as a silicon microcontroller, for complex hybrid systems. The system would then be subjected to a functional test.

Printed electronics do not generally require the traditional moulded plastic chip packaging. Rather it is possible to print components and entire circuits directly onto a housing, display, or printed circuit board. Essentially, in many applications the substrate acts as the component packaging.