Low-Temperature Polysilicon Process Bodes Well For Flat-Panel Displays

A joint venture promises a radically new approach to low-temperature silicon processing. It also signals a breakthrough for low-cost thin-film-transistor (TFT) flat-panel displays like organic LEDs (OLEDs) and LCD active-matrix displays. TCZ Inc. has combined the expertise of Cymer Inc., a deep-ultraviolet laser supplier, and Carl Zeiss SMT AG, a supplier of versatile optical systems for chip manufacturing and process control, to achieve this breakthrough.

TCZ's tool addresses the flat-panel display market. Its thin-beam directional crystallization (TDX) fills the void that holds back large-scale introduction of cost-effective system-on-a-panel (SOP) and systemon-glass (SOG) active-matrix LCDs and OLEDs. Leveraging the benefits of conventional excimer laser annealing (ELA) processing with those of sequential lateral solidification (SLS), it's part of the TCZ 900X system (Fig. 1).

In the new TDX approach, an optically created thin beam uses all available laser power. The higher-power laser drive (compared to conventional methods) provides a higher manufacturing throughput. The laser's long beam lets the system scan a flat panel's entire width without the stitching effects normally encountered with present methods. It also allows for lateral growth on a planar surface topology (Fig. 2).

"Cost trends are a major driving force in flat-panel displays. This is creating the need for higher-throughput, higher-yield, and lower-cost manufacturing processes, which we know will be made possible by our TCZ 900 system," explains TCZ's CEO, Brian Klene. "Yields and quality levels will increase up to twofold."

Klene expects normalized costs for OLEDs to drop below those of LCDs within a couple of years. Both technologies' costs will decline. For details, see ED Online 11123 at www.elecdesign.com. Also, the companies' Web sites feature a video of the process.