A huge chunk of Samsung and SK Hynix memory production is in China. Especially SK Hynix. Look it up.
www.taipeitimes.com
If our industry could make chips with powerpoint the answer would be obvious, not EUV. Given the order book for high NA EUV, the real answer was made years ago to go down that road.
High-NA EUV could very well be a bad decision. There is no High-NA EUV print data. But we have enough information from existing EUV to show even that was questionable.
You assumed EUV got you out of multipatterning, but that is not the case, even for High-NA (i.e., stitching of multiple exposures).As for any other process, is not a matter of "best technology" but of "what does it well enough at the right cost". Then the issues are "well enough" and "right cost" that may differ among players. EUV certainly does it well enough (even "better" arguably) and cheaper than multi-patterning at 7, 5 and 3nm for most of the current players. And when I say right cost, that includes the overall good die/wafer yield factored in, not just the pattern/etch process. I still remember a paper I (very marginally) contributed years ago showing excellent results of x-y pattern decomposition to use dual exposure in 193nm dry tools that was simply worthless with the introduction of 193i.
Will EUV be the solution of choice for the next nodes is a debate to which Fred brings always good points but, I think, it is still from over and depending on multiple issues from materials, blanks, reticle patterning to computational tools and litho tools. But for the past ones the history is written and whoever will use other techniques will be economically at a disadvantage.
I am not sure that is significantly the case, since EUV didn't get on all layers, especially 7nm. DUV double patterning still cheaper than EUV. On 5nm, the cost overall still went up since there was EUV and DUV multipatterning. I think there is still a common misconception that resolution is strictly determined by wavelength and NA. Actually for EUV, it's electrons and stochastics. Those can't be inverted, at least currently.
I guess you can mathematically do something like inverse transform to calculate what the exact wavefront at the mask surface should be to match your target pattern, but the problem is that both phase and intensity of thus calculated "mask" wavefront are continuous or analog signals (spatial functions). Today's analog/reflective SLM micromirror array probably allows you to control 32-64 levels of phase/position to mimic the continuous phase map, but I am not aware of any technique that can simultaneously control/mimic the continuous light intensity distribution at the mask surface. All we can do today is to approach them as close as possible to minimize the errors. The other problem is the defined "mask" region according to the inverse transform will be (-infinity, +infinity), but the mask size is limited and some spectrum will still be lost. If both phase and intensity signals of a large enough mask can be accurately controlled, that means one can construct any pattern they want through the inverse transform. Then the diffraction limit will disappear and this will definitely lead to a Nobel prize.
Doubt that it is always the case, otherwise EUV would not sell. For some layers it is clearly an economic advantage somehow.
Excellent point. That was the oversimplification that fails the moment we deals with stochasticity. At that point we move from classical to quantum optics and the inversion does not make sense anymore.
That was the reason I pointed out the feasibility of the mask. Clearly in reality we will always have finite domains being in the frequency, phase or spatial one so all solutions will be approximate. If I re-express my point, the question is if that approximation will be enough to use one of the current tools/techniques to image the requirements of 1nm and how much below. Or do we need to look for other tools (EUV High-NA, e-beams, ..) because the barrier is not avoidable.
EUV had to be bought and subsequently used before the data was in, apparently. About the costs, some references below. Keep in mind, EUV resists are many times more expensive than DUV resists.
Fred is pessimistic to EUV from day one. He raised questions about stochastic, through slit best focus drift, mask 3D effect, blurring effect in EUV generated 2nd electrons....., even though there are millions EUV wafers printed. There are difference between engineering works and scientific studies. He is right, but it seems work arounds have been validated and implemented in the field.
