11 July 2011

Ushio debuts first 200mm full-field projection litho tool for LEDs, plus 150mm laser lift-off system

Tokyo-based Ushio Inc has started shipping what it claims is the first 200mm-wafer full-field projection lithography tool (UX4-LEDs FFPL 200) for manufacturing high-brightness (HB) LED chips. The firm has also completed development of the UX4-LEDs LLO 150 laser lift-off system for high-volume manufacturing of vertical-structure LED chips on 150mm wafers.

The latest models in the UX4-LED range are based on the same platform as Ushio's field-proven UX series, which has an installed base of more than 1100 systems.

The UX4-LEDs 150mm-wafer full-field projection lithography tool (launched last November) has already been used for high-volume manufacturing at LED chip makers in Japan, Korea, Taiwan and China, notes Ushio. The new UX4-LEDs FFPL 200 has a  200mm-diameter full-field projection lens mounted on the common UX4-LEDs platform to enable full-field projection exposure of a 200mm wafer, with a high throughput of 120 wafers per hour. Unlike stepper systems, for which productivity reduces as wafer size increases, the UX4-LEDs FFPL 200 uses the full-field projection method to enhance its productivity by increasing the wafer size. It hence allows further enhancement in productivity and a reduction of the cost-of-ownership (CoO) in the LED lithography process, claims Ushio.

The system is designed to automatically handle wafer-size conversions up to 200mm wafers, and has a modular platform for future upgrades. It is also completely non-contact to cause no mask damage, and has a large depth of focus and special wafer chucking to cope with warped wafers. Also, special alignment technology accommodates low-visibility alignment marks. An optional backside alignment function support wafer-level packaging LED applications.

Laser lift-off (LLO) technology — for stripping a gallium nitride (GaN) film from a sapphire substrate — is indispensable for increasing LED brightness, says Ushio. Leveraging a field-proven KrF 248nm-wavelength excimer laser (well known for high repetition frequency and high stability as well as proven deep-UV optical technology), the firm has developed the UX4-LEDs LLO 150 laser lift-off system, which can achieve both high yield and high throughput. The system can also contribute significantly to reducing LED manufacturing costs, claims Ushio, because it allows reuse of sapphire substrate up to 150mm in diameter by stripping the GaN film from the entire sapphire substrate surface.

Tags: Ushio Lithography LEDs Laser lift-off GaN Sapphire substrates

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