ArF excimer drives lithography to 32 nm

06 Dec 2007

Gigaphoton has released a 90W argon-fluoride excimer laser for use in next-generation semiconductor manufacturing.

With a power output of 90 W and a repetition rate of 6000 Hz, the new ArF excimer laser from Gigaphoton has been designed for immersion lithography tools that will create features on semiconductor wafers just 32 nm wide. Chipmakers worldwide are just starting volume production at the 45 nm technology node, with manufacturing at 32 nm slated to start in 2009.

Immersion lithography is one of the techniques now being developed to continue the relentless miniaturization of electronic circuits. Most chipmakers believe that conventional "dry" optical lithography tools do not offer the resolution required for patterning at 45 nm and beyond, which has driven the development of techniques such as immersion lithography – where the light travels through a pool of water before reaching the wafer – and lithography using extreme ultraviolet (EUV) light.

Gigaphoton already manufactures 193 nm ArF excimer lasers for use in immersion lithography at 45 nm. In 2005, for example, Gigaphoton started to ship its GT60A laser, which offers a power output of 60 W at a repetition rate of 6000 Hz. Recent enhancements include improved spectral bandwidth and better stabilizing technology, and Gigaphoton says that immersion systems exploiting these lasers are now ready for volume manufacturing.

The new GT62A laser has a power output of 90 W, some 50% greater than the company's previous versions, and has been designed for so-called double-patterning immersion lithography. This double-patterning approach – which in practice comprises a whole suite of technologies designed to enhance the feature density – is expected to be crucial for lithography at 32 nm.

According to Gigaphoton, the light source in a double-patterning immersion lithography tool must achieve high power output to increase manufacturing throughput. This increase in power output has been achieved through the developent of a new power supply, along with technology to manage the extra heat load. The GT62A also features an improved laser chamber and more durable optics to ensure reliable performance during high-output operation.

Gigaphoton's announcement follows the release of a 90 W 193 nm ArF laser by Cymer, the largest supplier of deep UV laser light sources to the semiconductor manufacturing industry, at this year's Semicon West. The XLR 600i exploits a recirculating ring architecture instead of the conventional power amplifier stage.

A 60 W version of Giagaphoton's laser is also available, which means that customers can operate at 60 W initially and then upgrade to 90 W when their processes demand a higher power output. Gigaphoton now expects the GT62A to be integrated into immersion lithography tools that will be used in major semiconductor manufacturing facilities by the middle of 2008.

Key specifications

Wavelength:193 nm

Max. repetition rate: 6000 Hz

Pulse energy: 10.0/15.0 mJ

Power: 60/90 W

Bandwidth (95% energy integral): < 0.35 pm