Two Meaglow series 50 hollow cathode plasma sources have now been installed at Hanyang University, South Korea, in the Nano-Device Engineering Laboratory. Apparently the first performed so well, they needed another. The picture to left shows the second source in operation at the university. A third plasma source has also now been supplied to a second group at Hanyang, as shown in the image below. To date six sources have been supplied throughout South Korea, and all the sources have been installed on locally built ALD systems with the cooperation of local vendors. Our local agent Paultec Company Ltd. can be contacted at firstname.lastname@example.org
Meaglow has sent 3 of its 4″ diameter large area hollow cathode sources to the equipment manufacturer Okyay Tech, www.okyaytechald.com. This Meaglow design represents a change in the plasma source paradigm of using small area high intensity plasma sources and then diluting the active species over a large area. Instead, these hollow cathode sources have about the same diameter as the substrate, and a very high plasma density over that whole area.
Meaglow has also produced 8″ and 12″ diameter versions of this large area design. Check out the Meaglow website for our other hollow cathode plasma products, www.meaglow.com
Meaglow’s Dr. Butcher visited Caltech’s Painter group this December to make some adjustments to their hollow cathode plasma source, which is being used to improve the quality of their nitride films. Dr. Butcher also gave a talk to some students while he was there. A big thanks to Steven Wood, who hosted us.
Some nice Raman and other optical spectroscopy results for GaN films grown at only 200 C with a plasma assisted ALD system converted to use with one of our hollow cathode plasma sources. The results have recently been published in. J. Vac. Sci. Technol. A 37 (2019) 050901 by Nese Gungor and Mustafa Alevli of Marmara University in Turkey. There are some impressively narrow phonon line widths for GaN grown at that temperature. This is the 28th paper we are aware of on ALD using hollow cathode plasma sources, and this paper continues to demonstrate the dominance in the low temperature growth of GaN by the Turkish groups making use of hollow cathode technology.
The main advantage of the hollow cathode plasma sources has been the reduction of oxygen contamination from the source itself. The attached image shows a quartz ICP source etched through over a period of some years by plasma etching. This source of oxygen contamination has been known since at least 1989 and is discussed in our company white paper “Oxygen Contamination in PE-ALD“. However, the hollow cathode sources are also high radical density plasma sources with many other lesser known advantages (see “Hollow Cathode Plasma Sources for Plasma Enhanced ALD and PECVD“).
Meaglow Ltd has sent it’s second Series 50 hollow cathode plasma source to South Korea. A big thanks to our local agents Paultec Co. Ltd. for penetrating into this market, we couldn’t have done it without them. The Series 50 is our most popular source, so it’s been good to see it’s sales into Asia. Most of our plasma sources have gone to the US, but Asia is our second biggest market with multiple sales to Taiwan, Turkey, India, and now, South Korea. There has also been a single sale to Israel.
Says company President, Scott Butcher: “Our biggest customer to date is actually the National Taiwan University, who have five of our plasma sources on site for various ALD systems, though sales to South Korea seem to be picking up. Results for the first plasma source over there have been very good and word is getting around. We hope to see a third sale later in the year“.
Meaglow will be there next week!
Dr K. Scott Butcher (pictured below) will be attending ALD 2019, but to give him a bit of time to go to some of the talks Meaglow will have a literature table. You can catch up with Scott by texting him on +1 807 252 4391 during the conference, or you can email him at email@example.com Scott will be happy to talk about plasmas and hollow cathode sources with you.
One of the potential benefits of Meaglow’s hollow cathode plasma technology is scalability. In a recent news article from June 2019, we mentioned that Meaglow was breaking the old paradigm of high density but small area legacy plasma sources, for which delivery to larger areas dilutes the active plasma species. The question has to be asked, why can’t a high density plasma source be the same size as the substrate? And the answer is, with a hollow cathode source it can.
Meaglow had already developed designs for 4″ and 8″ diameter hollow cathode sources for high radical flux delivery over a similar area during plasma assisted atomic layer deposition. Now those designs have been refined in a 12″ plasma source, the first of which has now been shipped to a customer in the semiconductor deposition equipment market. The cathode, shown above before cleaning, was all aluminum for compatibility with silicon processing. The current design has been tested for operation over a pressure range from 80 mTorr to 8 Torr, though other pressure ranges can be achieved through custom design, and lower pressure operation with this current source may also be possible.
Shown below, left, is the plasma source in our test chamber with nitrogen at only 100 watts of RF power, though the source is designed for operation up to 3 kilowatts. On the right is the plasma source itself.
Inductively coupled plasma (ICP) sources were developed for use in the semiconductor industry decades ago, at a time when mainly silicon oxide and silicon nitride were being deposited by plasma sources. Today new materials have more exacting demands, especially for plasma assisted atomic layer deposition. The older sources have problems with oxygen contamination from sputtered dielectric windows (typically quartz or alumina). However, apart from that, the idea of using a high density power source generated in a small area tube and then diluting the activated species over a larger deposition area may be an idea that’s had its day. Small area sources are used so that back flow of metalorganic into the dielectric tube is minimised, since such deposition can block RF transmission to the plasma gas, and potentially cause damage to the dielectric liner.
Enter the hollow cathode plasma source, free of oxygen contamination problems (see our company white paper on this issue) and able to cope with both metallic and insulating deposition on the cathode. Now a high density plasma source can be made to the same dimensions as a substrate – there is no need to dilute the plasma species over a larger area. The plasma source can also be brought closer in. The OkyayTech P100 (shown above) utilizes Meaglow’s large area high density hollow cathode source. Below is a useful table showing some results from the University of Connecticut group of Dr. Necmi Biyikli (pictured above). These demonstrate the advantage of breaking away from the old ICP plasma delivery paradigm.
Check out the Meaglow website at www.meaglow.com or contact us at firstname.lastname@example.org or +1 807 252 4391, for more information on our plasma products. Meaglow and OkyayTech collaborate to build ALD tools with new generation plasma sources. You can check out the OkyayTech website at www.okyaytech.com or contact them at email@example.com or +1 818 318 9616, for more information on their ALD and ALE tools.