Doctor blade system for the deposition of thin semiconducting films

In this study, we present the development of a doctor blade system for the deposition of thin semiconducting films by solution casting. The developed system allows a low-cost production of thin-film transistors (TFT) on large-area substrates. The deposition parameters like the velocity of the doctor blade and the temperature of the substrate affect the layer thickness and process quality directly and should be analyzed to improve the deposition quality. The developed system is operated by a microcontroller, which is responsible for adjusting the motor velocity and controlling the substrate temperature. The control system allows setting the velocity between 1 and 500 μm/s and the substrate temperature from 20 to 100°C. The implemented LCD display with control elements provides the user interface and allows setting up and controlling the process parameters. The high quality step motor drives the linear actuator with the attached substrate and realizes the relative movement of the doctor blade over the substrate. The micro-step control algorithm provides the high resolution and smooth movement of the substrate. The heating system is realized by a self-adhesive heating film and sensor element, mounted on the substrate. Additionally, an ultrasonic excitation of the doctor blade realized by an attached ultrasonic transducer can be used to improve the layer quality.