C.M.J. Mutsaers

Low-cost all-polymer integrated circuits

A technology has been developed to make all polymer integrated circuits. It involves reproducible fabrication of field-effect transistors in which the semiconducting, conducting and insulating parts are all made of polymers. The fabrication on flexible substrates uses spin-coating of electrically active precursors and patternwise exposure of the deposited films. In the whole process stack integrity is maintained. Vertical interconnects are made mechanically. As a demonstrator functional 15-bit programmable code generators are fabricated. These circuits still operate when the foils are sharply bent. Due to the limited number of process steps the technology is potentially inexpensive.

Electroplating of conductive polymers for the metallization of insulators

Abstract Electrodeposition of copper was investigated on thin films of poly(3,4-ethylenedioxythiophene) (PEDOT). This conducting polymer can be processed from solution and exhibits a high specific conductivity of about 300 S/cm. N -(3-Trimethoxysilyl-propyl)pyrrole was applied as a primer in order to adhere PEDOT to the substrates. The lateral propagation or front velocity of the copper front and the uniformity of the copper deposit were determined as a function of sheet resistance of the PEDOT films, type of PEDOT counterions, and of the temperature, applied potential and composition of the electrochemical baths. The experimental data obtained are interpreted using a simple mathematical model to describe transient thickening during electrodeposition on electrodes of high ohmic resistance. A good agreement with experimental data is obtained, especially for the front velocity being inversely proportional to the square root of the sheet resistance. Quantitative analysis of uniformity data shows that the affinity for nucleation is much higher on the conducting polymer than on the deposited metal. This conclusion is supported by activation energies as determined from temperature-dependent metallization experiments. Finally, adhesion of copper deposits as a function of copper thickness and morphology of the substrate are discussed.

Organic field-effect transistors and all-polymer integrated circuits

Electrical properties of field-effect transistors made of different solution processable organic semiconductors are described. The temperature and gate-voltage dependence of the mobility is shown and theoretically described using a model based on the variable-range hopping of charge carriers in an exponential density of states. Furthermore, a technology has been developed to make all-polymer integrated circuits. It involves reproducible fabrication of field-effect transistors on flexible substrates, where the semiconducting, conducting and insulating parts are all made of polymers. Integrated circuits consisting of more than 300 field-effect transistors are demonstrated.

Polymeric integrated circuits and light-emitting diodes

All-polymer flexible integrated circuits have been fabricated using a potentially low-cost technology. Combination with commodity anti-theft stickers has led to functional radio frequent identification transponders. Polymeric light-emitting diodes (PLEDs) opened the way to cost efficient, large area display-applications. Directions for further enhancement of their performance are presented.