social media is passing around an announcement that Huawei is testing a China domestically developed UV machine the machine uses an euv light source known as laser induced discharged plasma or ldp this is in contrast to asml method which is called the laser produced plasma or lpp method it is claimed that ldp is much more efficient than lpp smaller simpler and better Energy Efficiency has asml just been deeps I've been asked to speak on this via email and Twitter and I guess I have to do it there is so little out there about how this machine works so I'm not going to speculate but people have tried ldp before and we can talk about that feel free to extrapolate from there in today's cope video let's take a look at the laser induced discharge plasma euv light source when we are talking about the euv light source we're talking about producing 13.5 nanometer light as sml's lpp based light source is famous in it a carbon dioxide laser hits a droplet of tin twice the first laser pulse flattens the tin droplet into a disc shape and the second laser pulse is more powerful when it hits the droplet it creates a tin plasma the plasma emits the 13.5 NM light we want from there this light must make its way through a complicated Optical system consisting of anywhere from 6 6 to 10 mirror Reflections and unfortunately each mirror reflects a little less than 70% of the euv light that hits it since so few photons ever make it to the wafer an euv light source has to generate a lot of photons this is measured in units of Watts or the number of photons generated per second the initial goal was something like 250 Watts go much lower than that and it's like trying to warm a pizza with a dim heating lamp you wait forever or never get there asml didn't automatically choose lpp at the start in the early 2000s people knew that lpp had serious problems like the part that depends on an unstable CO2 laser hitting an unstable near microscopic size tin Target from several meters away at the time the community considered this difficult so vendors explored a range of light generation options one of those alternate options was DPP DPP stands for discharge produced plasma method the DPP method produces euv light by discharging a strong very brief electrical current between two electrodes essentially a lightning bolt between the two electrodes there is a vaporized fuel pre-ionized to ensure a more conductive path for the coming discharge and to achieve a nice uniform effect the discharge comes from a powerful capacitor Bank when fired the current flows in a line along the z-axis between the two electrodes through the fuel Vapor ideally a straight line but not always this creates a powerful magnetic field that forms circles around the current like fingers closing around a wire the field constricts and confines the fuels ionized particles creating a plasma inside the field squeezes it inwards heating it to higher densities and temperatures of up to 200,000 de C when done right it creates a plasma hot and dense enough to emit sufficient UV radiation that we can collect because the electric current discharged moves along that Z AIS we call it the Z pinch does this name sound somewhat familiar perhaps you heard of it from when Z pinch was investigated back in the 1950s as one of the first approaches to nuclear fusion energy yes that is how crazy euv is we need nuclear fusion energy Tech in a manner of speaking in the early days of EU V like the late 1990s and early 2000s DPP was investigated as a possible Light Source by two companies extreme ultraviolet phography system Development Association or eua over in Japan this was a large joint organization with participation from various Japanese companies and academics and the second company was Phillips extreme UV a joint venture between Phillips and the fronhofer institute for Laser Technology one of of the major differences between the two setups in the early 2000s appears to be the choice of vaporized fuels there were three fuel options Xenon tin and lithium UVA studied DPP using Xenon while Philips extreme UVS variant of DPP championed tin nobody seriously tried to commercialize lithium apparently because lithium atoms and ions are very small if used as a fuel lithium atoms risk diffusing into the mirrors and all other solid parts of the tool poisoning them Xenon fuel DPP sources were used in early UV prototypes like the micro exposure tool in 2004 a few others were installed in the R&D Labs of Intel and semitech but in the end tin emerged as the best candidate more of its ions produce light bands within 13.5 nanometers and that light was less likely to be absorbed by its own ions so in all a tin setup was expected to convert more of its wall plug power into euv Power 2% rather than the 0.5 to 0.9% for Xenon DPP is a simple method and it let Philips extreme ship a light source by 2003 the main issue with the DPP methodology has to do with repetition if we want to raise the UV light source's power level then we must have many discharges by some calculations the electrodes must discharge thousands of times per second to achieve the minimum economic goals of 120 Wafers per hour the pulse power technology struggled to achieve that kind of speed such speeds presented serious thermal damage concerns for the electrodes you know from having to deal with thousands of lightning strikes and fusion class plasma temperatures one more issue tin vapor condenses on cold surfaces necessitating extensive engineering to heat the tool surfaces to keep tin films from forming for these reasons in the mid to early 2000s Philips extreme UV evolved their DPP method into ldp the early ldp setups had two rotating tin Supply discs these discs connected to large energy storage capacitors will also serve as the electrodes the discs rotate through bass of carefully temperature controlled liquid tin coating their surfaces with a tin film then either a pulsed carbon diox oxide or neodymium doped yag laser Fires at the tin film on one of the disc's surface creating a tin Cloud called a pre-plasma between the electrodes from there the same thing happens we fire a big Electric discharge to generate the Z pinch and from there the hot and dense plasma for UV light this method offers some compelling upsides ldp's wheel setup sidesteps some of the technology challenges of lpp namely trying to hit the tin droplet in lpp every time the laser pulse misses the droplet we suffer an efficiency loss but with ltp since the wheels are always turning and replenishing their tin films the laser is basically guaranteed to hit some tin somewhere on the wheel so indeed there are efficiency benefits to be had here it was also argued that any heat transferred to the wheels by the zinch and there is probably a whole lot of it can be mitigated by said Wheels dipping into the liquid tin bath this new design also offers some debris mitigation benefits a foil trap is included to capture tin debris flying off the surface at the cost of some euv light loss in 2005 Japan's usio group bought 50% of the Phillips extreme UV company a few years later in 2008 they purchased the whole thing renaming the company to Extreme Technologies and started doing joint research on euv light sources the resulting DP light source was revealed in 2010 as the tin DPP Source collector module or Soo its electrodes fire powerful discharges of up to 20,000 amps basically a small lightning strike lasting for just a few hundred nanoseconds during operations we discharge anywhere from 10,000 to 20,000 to up to an insane 100,000 times per second by adjusting either the discharged pulse repetition Pace or the energy of each pulse we get stronger euv output power a higher pulse energy at a lower frequency can produce the same output as a lower pulse energy at a higher frequency they pitch ldp as having the best of both lpp and DPP scalability and stability ldp also seemed physically smaller and simpler in concept probably why asml used an ldp light source in its first Alpha demo tool and as reported in an October 2010 i e Spectrum article on euv they kept close tabs on both methodologies ldp through extreme and lpp through the startups Simer and gigaphoton in the end though asml switched away from the ldp source adopting lpp without talking to someone who worked there and no one responded to my emails it is hard for me to find out exactly why but I have a few theories the simplest theory is that ltp could not scale output power as fast as lpp can in 2008 extreme announced that it was is capable of producing 500 watts of euv power output at plasma at plasma refers to the measurement of the euv power emitted by the plasma itself right at the light source stage sounds quite high but remember that the light still must go through all the reflections towards the wafer the UV power actually reaching the wafer is measured using a metric known as power at intermediate Focus Soo whilst using one set of UV light collectors had a measured power at intermediate focus of 14 watts corresponding to about 7 to 8 Wafers per hour if equipped with an improved UV light collector armed with additional reflective surfaces then that theoretically goes up to 34 Watts better but still short of Simer 250 watts and gigap photons 104 Watts at intermediate Focus as reported by I Spectrum to achieve 500 watts at intermediate Focus extreme said that ltp would theoretically need to hit 4,000 watts at plasma based on their accompanying graph this can be done if they discharged 50,000 plasma pulses per second with each pulse discharge releasing about 80 M pulse energy perhaps this was too much to engineer with the heat generated by the Z pinches too difficult to dissipate the paper authors did seem to imply that there was some kind of physical limitation at the aforementioned 80 m per pulse metric not clear based on the re maybe it was something else earlier studies with Xenon plasma found that as we pump more power into the Z pinch the generated plasma becomes larger rather than brighter this larger plasma emits UV light beyond what the collector mirrors can physically collect essentially wasting energy maybe something similar happened here one of the later announcements I dug up was in October 2011 saying that iio had achieved 30 wats power and intermediate Focus this was was up from the previous 14 watts but by then I think asml had seen enough and moved forward with lpp though the community did keep debating over the choice as late as 2014 usio kept on using the ltp method to generate UV light for special mask blank inspection tools a 2022 paper about the tools showed output of about 250 Watts at plasma I'd probably Muse that that is your local maximum for this technology and a works fine for checking Mass blanks but not for litho lpp on the other hand has scaled quite well for asml late last year it was a mentioned that asml research team in San Diego hit 740 Watts euv power recently I presume at intermediate Focus they expect to productize that shortly China continues working on a technique to produce euv light for their own domestic use they're chasing All the known UV light source methods including lpp and free electron Las lasers so it should not be a big surprise that they're looking at laser assisted discharge plasma 2 in 2023 there was a publication from a research team in the school of aeronautics and astronautics at The harpine Institute of Technology there seems to be a small cluster of researchers working on a DPP on ldp ever since the early 2010s there are a few papers out there from other Chinese organizations investigating ldp plasma Dynamics and simulations a casual reading of these papers didn't find anything I consider groundbreaking if anything it seems rather unimpressive with lower conversion efficiencies than setups in 2005 and 2006 but I suspect they are hiding their strengths there will certainly be some people out there who just want me to say something like oh China can't catch up with asml or China will certainly achieve euv or China will destroy America's blockade oh and how that all affects asml stock I don't do stock analysis I do want to say that I think China achieves euv eventually after all euv is a technology made by man nothing is impossible I'm also willing to say that it happened sooner than you think they're spending so much money and putting so many smart people on it and there is already so much published research out there on the quotequote golden path the Chinese have the benefit of knowing that it can work and knowing conceptually how it's done that's like 60% of the job kind of side note I recently saw an interesting paper posted by Fred Chen on LinkedIn discussing an exploratory effort by Russian academics an 11.2 nanometer euv light and ruthenium brilia mirrors I don't see that particular effort scaling but do respect that people are exploring alt euv setups I'd never presume people back then had all the answers anyway I doubt that any China euv machine will be economically competitive with an asml euv machine at the start it might pattern far few Wafers per hour less than 100 Wafers even or pattern with worse resolution so on people might ridicule it as a bond doggle or a toy but I do believe that the machine will be clever with an interesting twist for example if the ltp method is not bright enough then perhaps it has a Nifty two mirror optic system to deal with that shortcoming asml should study whatever does come out whenever it does and consider possibly integrating it and finally I believe one of China's superow an Asian one in general really is being able to tolerate a business making no money for years on end asml reported gross margins are about 51% I don't know what's in that service tools components Etc but I reckon those need to go down when the time comes to beat back the Chinese challenge all right that's all for tonight uh sorry about my voice is not sounding that great uh subscribe to the Channel Sign up for the patreon and I'll see you guys next time