Wendell T. Blonigan

Low temperature polysilicon chemical vapor deposition system for thin film transistor liquid crystal diode

Polysilicon thin film transistor (TFT)-based displays are increasingly found in cell phones, mobile communicators, PDAs, portable DVD players, and mobile computers because they have high resolution and low power consumption. The AKT plasma-enhanced chemical vapor deposition system made by Applied Materials is used to deposit multilayer dielectric films including precursor low-hydrogen-content amorphous silicon for manufacturing these displays. The polysilicon film is converted from an amorphous precursor film by an excimer laser annealing process. Production of a good quality polysilicon precursor film requires that the hydrogen content of the film be controlled below 2%. Achieving low hydrogen content requires uniform treatment at high temperature (500±10 °C) after deposition. This article describes the design and performance of the large, high temperature heat chamber integrated in a cluster-tool-based deposition system for both preheat and postannealing of the substrate. [Q. Shang, J. K. Kardokus, and ...

Rapid cooling dual slot load locks for liquid crystal display

Rapid cooling of 680×880 mm glass substrates was demonstrated in the dual-slot load locks [S. Kurita, W. Blonigan, and A. Hosokawa, U.S. Patent pending No. 7828.7017 (December 1999)] of an AKT 5500 chemical vapor deposition system. Two complimentary techniques are used to cool a substrate from 400 to 60 °C within 33 s while maintaining a temperature uniformity of ±5 °C. Helium equivalent to a partial pressure of 9 Torr is injected at the initial stage of venting. Cooling plates are located as close as 8 mm above and below the substrate while cooling. Rapid-cool dual-slot load locks reduce cost by eliminating large vacuum pumps and machine components. Uniform cooling eliminated undesirable thermal stress during cooling and thus enabled reliable substrate handling.