Irresistible Materials for next generation 1nm EUV
With imec and ASML renewing their collaboration into the next generation of extreme UV (EUV), there is a challenge with the materials that are needed alongside the multimillion dollar EUV machines for next generation 1nm chips.
A spinout of the University of Birmingham in the UK has spent a decade developing a new generation of photoresist for just this application all the way down to 7A where the layers are just 7 atoms thick. New CEO Dinesh Bettadapur at UK startup Irresistible Materials talks to Nick Flaherty.
“EUV is s huge set of challenging requirements and there’s no easy answer to optimise the photoresist,” he said.
Bettadapur is a former CEO of ASML MaskTools who joins from mask tool EDA firm Silvaco and was previously a programme manager on the Itanium processor at Intel.
He has been brought in to ramp up the business. “The time is now and this is a very significant opportunity for us so we have to execute as quickly as possible to lead to a successful outcome. There is a sense of urgency and purpose.”
The company started out using fullerene but has moved on from that to use an organic material can be triggered in different ways.
“It’s a balancing act of factors such as resolution and line width roughness,” he said. “It’s definitely not one size fits all. A single recipe doesn’t meet the requirement of all customers and not even the individual layer requirements. The requirements for contacts, pillars and lines are all different so we will have different formulations for each layer for each customer.”
“We started with a fullerene based material but it had certain issues so we came up with a non-fullerene organic compound a quencher, cross linker and a multi-trigger molecule. It’s like a chemically applied resist with a catalytic process so the photons trigger the reaction,” he said.
In a typical resist this creates an acid diffusion that can’t be well controlled. Instead the material controls the acid diffusion with a chemical trap, building up another reaction to build up a chain of molecules.
The company is using for a range of process nodes using EUV, but the challenges of the resist for high NA lithography are even more complex.
“We intend to enable multiple process nodes but High NA brings bigger challenges in the absorption and depth of focus which is a huge issue so we have to come up with an even better formulation which we are actively working on,” he said.
“The existing material can work with high NA but specifically addressing the additional challenges we are working on a different formulation, starting with the same foundation. We have a very active collaboration with imec and we want to test all of this out.”
“Our material is a very thin resist and we have been able to get down to 18nm and even after litho processing we are left with a 16nm etch so the amount of top loss is very small and that’s a key characteristic and that means there is less to deal with for the edge etch. This means we should be able to supply support requirements of 7A, it’s eminently scalable.”
“We have opportunities to intersect with the requirements of chip maker this year and next year. They are definitely in the process of material qualification.”
There are also geopolitical issues for ensuring a sovereign supply chain in both Europe and the US. “We are engaged with the EUV centre Albany and we are doing some work there,” he said.
“Our supply can be flexible as we have four or five elements that make up the resist and each of these could be sourced from the US only or from other places but that means we would need to find partners in the US if that becomes necessary. We put everything together and send out the complete formulation and we intend to work with scale up manufacturing partners who would manufacture in volume. That volume depends on the target device, whether it’s a foundry or IDM, the quantities we talk to customers about is a wide range from 100 gallons a months to 1000 gallons or more.”
Nano-C are making part of the material and would be the manufacturing partners but the company is talking to suppliers in the US, Europe and Asia to scale as quickly as possible. “There is no reason why we could not do it all in Europe and the testing will definitely be done in Europe through imec,” he said.
This is an obvious point for a funding round. The company is backed by US materials supplier Nano-C and Mercia Asset Management
“We wouldn’t have been able to have survived 10 years without funding, and funding is always welcome and we have funding right now but as we accelerate the roadmap we will continue to look for additional sources, we are open to customer funding, VC and other strategic investors,” he said. “I have a very good idea of how much we need but I just can’t tell you.”
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