The number of excimer laser units sold for use with semiconductor lithography started to show steady growth last year due to the recovery in neon (Ne) supply.

As large amounts of neon (Ne) are consumed for lasers to oscillate, the excimer laser unit market became transiently sluggish due to the worsening political situation in Ukraine – which holds a large market share for Ne.

However, with producers promoting greater gas efficiency and the expansion of support setup, there was a turnaround in the trend leading to an increase in sales.

For excimer lasers, two different gases are inserted into the laser chamber; either fluorine and krypton (KrF) or fluorine and argon (ArF). Energisation occurs when high voltage is applied, creating an excimer. When the excimer breaks up, ultraviolet light is emitted and amplified with a light collective mirror causing the laser to oscillate.

In addition to KrF and ArF gases being used, Ne is used as the atmospheric gas in the chamber. Ne accounts for around 95% of the gas used in excimer laser processes, which accounts for around 70% of the world’s demand for Ne. KrF lasers typically consume around 10-50 kilolitres (KLs) of the yearly gas consumption, with ArF lasers consuming around 60-200 KLs.

The main producers of quality gas certified for use by laser manufacturers are Linde, Air Products, Air Liquide, Nova Gas Technologies, Praxair and Tokyo Gas Chemical.

With the price of Ne skyrocketing in parallel with the political situation in Ukraine worsening, excimer lasers were forced to undergo urgent improvement, leading towards greater efficiency in the amount of gas used during the process to lessen Ne consumption during the shortage.

For a time, the price of Ne was over $5 a litre, even swelling to $8 at certain points. However, the price has been in a downward trend since Q3 2015 due to the expansion of supply capacity in China.

Electronics wafer close up

Despite prices beginning to downtrend, the manufacturers are focusing on gas usage again – pushing forward to develop greater efficiency and an expanded support setup.

Excimer lasers and the miniaturisation of semiconductor processes have been evolving. Semiconductors, through amassing a large number of transistors on the substrate, are enabling high level and high speed information processing as well as increased capacity and a reduction in costs.

However, the width of the circuit wiring has to be made as thin as possible to amass transitors. As a result, efforts have been made to shorten the wavelength to engrave a minute circuit pattern as well as to achieve a higher power output.

Before this change ArF lasers measured 193 nanometres (nms), but in using an ArF liquid immersion laser along with water filled between the projection lens and the wafer in the exposure unit, exposure can be accomplished with a shorter wavelength of 134nm.

Technology developments

There are only two companies currently producing excimer lasers for semiconductor lithography in the world. The first, Cymer, was established in 1986 and is headquartered in San Diego, California. Its products are installed in semiconductor lithography units supplied by ASML, Nikon and Canon. Up until now, the company has delivered 3,800 units to the world’s major logic, memory and foundry chip producers. Cymer Japan, which was founded in 1991 and is headquartered in Tokyo, began to expand through sales and services.

Looking back, the President of the North Pacific rim unit, noted, “The sustainability of a continuous supply and price fluctuation of Ne greatly affected the semiconductor industry. In 2015, our customers strongly requested that we develop new technology right away and that we take the lead in the industry regarding the use of Ne.”

“The entire company was involved in responding to these requests and we succeeded in reducing the amount of Ne used by about 70%. We also developed technology so our lasers could operate in a more stable fashion. Our customers, corporate headquarters in the US and our service group all joined together and, based on in-depth cooperation, we were able to expand quickly into the field.”

“As a result, and in a very short space of time, we succeeded in a major reduction of the amount of Ne used on a global scale.”

In terms of future prospects, he went on to say, “To reduce the costs of operations, to offer the technology demanded by next generation services and the solution for a greater stable operation of facilities, I would like to continuously meet the requests of our customers by working together with them.”

The second company, Gigaphoton, is the only manufacturer of excimer lasers for use with semiconductor lithography in Japan. The company is engaged in the development, manufacture and sale of both KrF and ArF lasers and has sold a total of around 1,300 units so far.

The company was established as a joint venture between Komatsu and Ushio but became a wholly-owned subsidiary of the former in 2011.

“In a very short space of time, we succeeded in a major reduction of the amount of neon used on a global scale”

President of Cymer Japan

Its major buyers are semiconductor lithography facility producers such as original equipment manufacturers (OEMs) ASML, Nikon and Canon and end-user chip producers such as Toshiba and Samsung Electronics.

Overseas sales currently account for around 80% of its total sales capacity but by establishing service centres in various locations both nationally and internationally, the company has positioned itself to meet the demands of its customers.

Its major product is an ArF liquid-immersion laser named the ‘GT64A,’ with the number of units sold since going on sale in 2014 continuing to grow. The instrument can produce an output of 120W by linking two laser chambers. It also features an automatic adjustment function, with the output controlled to suit the user’s process. As such, the product can reduce costs and lessen the burden on the environment.

Last year, the company was hit by both the soaring price of Ne and the global uncertainty surrounding supply. In a bid to minimise disruption for its customers, the company launched its ‘Neon Gas Rescue Programme’ – an initiative that involved offering technology called ‘eTGM’ which could reduce the consumption of Ne by up to 50%. The company offered this technology free-of-charge for a limited time.

The package also involved a major reduction in quality gas evaluation time as well as developing and supplying recycling technology. The ‘Neon Gas Rescue Programme’ was a success and helped to boost Gigaphoton’s sales in 2015.

Regarding recent trends in sales, Chief Corporate Planning Manager Akinori Matsui stated, “Since 2010, the semiconductor market has become extremely active in Korea, Taiwan and even China. Last year, the increase in KrF laser sales really stood out.”

In terms of future prospects, he commented, “This year will be a very prudent year for semiconductor producing facility investments, primarily due to the effects of the drop in DRAM and flash memory prices. Gigaphoton will continue to pursue improvement in laser capabilities and will contribute to stable operation for our customers.”