By Ed Korczynski, Sr. Technical Editor
Wenge Yang is vice president of corporate marketing for Entegris, and before joining the company in 2012 he earned a Ph.D. in Materials Engineering and served in various executive roles at Advanced Micro Devices, Tokyo Electron, and two startup companies, so he has a uniquely valuable perspective on materials trends in IC fabs. Yang spoke with the Show Daily about major trends in High Volume Manufacturing (HVM), and about the topics that will be discussed in the Entegris Yield Breakfast Forum “Yield Enhancement Challenges in Today’s Memory IC Production” happening Thursday morning, July 14.
On the memory side the biggest challenge is that investment into different memory technologies has slowed innovation in DRAM. “People will hold the R&D money away from DRAM to try to find a DRAM-killer. So most of the innovation in memory is in 3D-NAND, and obviously Samsung is leading the industry with moves to build two new production lines to try to dominate the market.”
One of the known difficulties in 3D-NAND HVM is the etching and filling of contacts to the side “staircase” structure. Today the material used for contact fill is tungsten (W), while standard WF6 gas precursor shows some limits in ability to fill these contacts and in reliability. Going to more layers generally means deeper holes to fill, so fabs are exploring new fluoride-free-tungsten using chloride chemistry precursors which promise better process results.
“EUV lithography has been debated for many years,” reminded Yang. “Finally, it has been developed to the point that it will be used in 2018 for pilot and in 2020 for production. Logic fabs will use it for 7nm-node processing, while in foundry fabs the 5nm-node will be the insertion point.”
Inpria and many of the legacy photoresist suppliers are developing new metal-core photoresist chemistry for improved sensitivity and Line-Width Roughness (LWR) in EUVL. Yang explains that new handling technologies will be needed for such photoresists, “A new requirement in purification is needed, while the filtration requirement for particles remains. This comes along with what we call ‘metal-phobia’ at the leading edge. In the past part-per-trillion levels were not issues, while today the whole delivery path becomes an issue and customers now ask about the materials of construction of all fluid-path components to ensure that no contaminants leach out into chemistry.”
At the leading edge, a lot of focus is on gas purity requirements of new metal-organic precursors needed for ALD/CVD. “In reality, if we talk to IDMs they say that they honestly don’t know what is the right spec. Maybe part-per-trillion is too much, but they will say that they do not want to leave risk in the process,” confided Yang. “There are cases where a customer sees something happen and they can trace the problem back to a metal contamination level in a precursor. Obviously we know that less metal should be better, but we generally lack the ability to know exactly so the spec tends to stay at the prior node level.”
“In terms of the business dynamics, it is a challenge for us to create new products that meet the evolving needs of our leading customers,” explained Yang. “However the greater challenge is the serious overhead investment needed for more on-site customer support and more analytical lab tests. Supporting today’s customers is painful today, so smaller companies may find it too difficult and expensive to stay in the market.”
On Thursday morning of SEMICON West in the Yerba Buena level of the Marriott Marquis hotel, Entegris will host the 7th annual Yield Breakfast Forum. Micron will talk about XPoint manufacturing technology it has co-developed with Intel. XMC will talk about the dynamic of China developing it’s own materials supply-chain.