Jerome Perrin

Balzers Process Systems, Display Technology
5 rue Leon Blum, 91124 - Palaiseau, France
106027.3060@compuserve.com

The increasing size of glass substrate in flat panel display manufacturing (up to 1 m2) imposes constraints on the design of plasma processing tools, in particular for dry etching. Different reactor concepts are already used in production or tested in development. The most widely used concept is the classical capacitively-coupled RF discharge. But the discharge become more and more symmetric as the ratio of RF-powered electrode and grounded electrode areas tends towards unity. To overcome this problem of scaling-up and provide control of the ion energy on the substrate, we have developed a new triode configuration (Piano reactor) involving a periodic structure of isolated bars with independent RF impedances to ground. Alternative concepts of inductively-coupled plasmas are now proposed, in a planar TCP configuration or with an array of cylindrical sources, but the controls of plasma uniformity and of electrostatic chucks for back-side cooling of the substrate are still difficult on a large area.

Plasma dry etching is gradually taking over wet etching in the fabrication of thin film transistors (TFT's) for active-matrix liquid crystal displays (AMLCD's). As a prototype example we will examine the various steps involved in the back-channel-etch TFT technology. Dry etching was initially restricted to the intrinsic and n+ amorphous silicon layers for the TFT-island and the channel, and to the silicon nitride gate insulator and passivation layers for contact holes. Now it becomes a must for the metal gate and source and drain electrodes at crossing points of lines and columns, and for the bottom ITO layer of the pixel.

Finally we will consider different concepts for mass production systems, and discuss the trade -off between substrate handling, etching rate and parallel processing to achieve a desired throughput.