Wafer Edge Exposure (WEE) is a prevalent process step in high-volume semiconductor manufacturing. The WEE process removes a round edge and ID region of a wafer after exposure in lithography tools like wafer steppers. Cost reduction in advanced packaging is the primary driver to install this additional high-intensity exposure step: It prevents the portion of the photoresist on the edge from being damaged during further handling, which may reduce the yield of semiconductor devices from the wafer. WEE equipment may be connected to a semiconductor wafer track as an independent unit or may be integrated directly into stepper equipment.
Currently, most WEE applications use broadband radiation in the spectral range between 350 and 450 nm. The most prevalent solutions are conventional fiber-coupled mercury discharge lamps with a rated power of 150 to 500 W. Because of the requirement for broadband exposure in WEE, finding more economical and reliable alternatives to these system setups was difficult. Primelite’s advanced light engines ALE/1 and ALE/3 come into play here, which are both designed to deliver their optical output via flexible light guides. Both systems cover the spectral range of conventional mercury discharge lamps and easily outperform the typical intensities required in Wafer Edge Exposure processes.
Wafer Edge Exposure hardware basically consists of a wafer scanning, a spinning device, and a powerful spot light source combined with optics to precisely expose the wafer edge. Our UV-LED light sources ALE/1 and ALE/3 perfectly fit into these setups: They are the only available solid-state lighting solution covering i-, h-, and g-line for broadband exposure of the wafer edge. Our eco-friendly UV-LED light sources ALE/1 and ALE/3 provide meticulously controlled output to ensure highly accurate exposure results. And in daily operation, our exposure systems can help your equipment efficiency. In general, the prolonged service life of UV LEDs improves tool downtime. But additionally, all our light sources feature field replaceable LED Modules, making maintenance as fast and easy as possible.
With an output spectrum highly comparable to mercury discharge lamps, our fiber-coupled UV-LED light sources are also particularly suitable for replacing conventional lamp technology in existing WEE processors.
A quick comparison between Primelite’s broadband UV-LED light sources and solutions powered by conventional mercury discharge technology shows an excellent spectral match while revealing a significant performance gap. And our UV-LED exposure systems put you in full control: Configure and drive the i-, h-, and g-line (the spectral range around the central wavelengths 365, 405, and 436 nm) individually, or use them all together if you need maximum output performance. Switching times at a millisecond add to precise exposure results, which are consistent both short- and long-term.
|Output Power [mW]1||Broadband|
|ALE/1.3 (CWL 365, 405, and 436 nm) 2||30,000||10,000|
|ALE/3.2 (CWL 365 and 405 nm) 2||13,000||6,500|
|200 W Mercury Discharge Lamp (typical values)||7,500||3,000|
1Power output measured at end of light guide (active core dia. 6.5 mm, length 1.5 m), deviation of ±10% possible.
2CWL of emitters: 367.5±2.5 nm, 402.5±2.5 nm, and 435.0±2.5 nm.