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They need the mirrors for shaping the light before the mask and projecting it afterwards. These mirrors have to be in a hydrogen ambient of >30mTorr, much higher than the vacuum in the accelerator. A transparent membrane would not be able to stop hydrogen from leaking or even busting through.
ASML's solution need hydrogen atmosphere，the "particle accelerators" solution does not. The purpose of hydrogen atmosphere is to reduce tin droplet contamination on the mirror
ASML's solution need hydrogen atmosphere，the "particle accelerators" solution does not. The purpose of hydrogen atmosphere is to reduce tin droplet contamination on the mirror
The accelerator is only the EUV light source; everything afterwards (mask, optics) is exposed to contaminants from the resist, so the hydrogen is still necessary.
The accelerator is only the EUV light source; everything afterwards (mask, optics) is exposed to contaminants from the resist, so the hydrogen is still necessary.
Scattered tin debris from the vaporization of droplets is a major potential source of contamination of both the collector and focusing optics. Unmitigated, the lifetimes of these expensive components would be unacceptable. Hydrogen gas is used to shroud the tin excitation region, and tin vapor and aberrant droplets are reacted to form stannane (SnH4), which is then removed from that section of the housing by means of the vacuum line. Higher flows of hydrogen can be used in periodic plasma-based cleaning to remove tin that deposits on the collector optics.
It can be considered a primary reason but there are residual hydrocarbons and water vapor especially from resist which also contaminate the downstream elements.
Theoretically, it would be ideal to do EUV lithography in vacuum conditions since EUV photons are absorbed by any medium. However, in practice a background gas of roughly 5 Pa hydrogen (H2) must be used, to maintain self-cleaning conditions for the sensitive EUV mirrors.
They need the mirrors for shaping the light before the mask and projecting it afterwards. These mirrors have to be in a hydrogen ambient of >30mTorr, much higher than the vacuum in the accelerator. A transparent membrane would not be able to stop hydrogen from leaking or even busting through.
I just read about a possible alternative to the membrane window. If you have a small enough orifice tube and the beam can squeeze through it, a pressure differential can be maintained. But the beam size is generally mm's, a sufficiently small orifice could cut out some light (and heat up).
They mentioned the application of photoemission spectroscopy so they should know EUV produces photoelectrons, should question the use for lithography with this knowledge.
SCMP is now definitely a cheerleader for the CCP. Absolutely. Owned by Alibaba. Most of the writers are based on the mainland.
Unfortunately it seems Digitimes starting to do the same too.
I have no knowledge about the particle accelerator. But is it a very expensive and bulky approach considering ASML already achieved EUV volume production without using it?
I have no knowledge about the particle accelerator. But is it a very expensive and bulky approach considering ASML already achieved EUV volume production without using it?
In some designs the ring can have more that one outlet, each outlet coupled to a different tool, but the Tsinghua design is not yet that versatile. It is non-trivial to recover the electrons and accelerate them into another segment of the loop. The alternative is to switch one source beam between multiple wigglers and outlets, but then they might not recirculate the electrons. Only a fraction of the energy is harvested in a wiggler so the most efficient and advanced designs recirculate the electrons which are used to boost a new electron burst as it enters the loop. Perhaps they could arrange to converge the multiple wiggler outputs for that.
By Wang Jie The Chinese internet has been abuzz recently about news of a breakthrough by Chinese scientists developing an ultra-deep ultraviolet light source for photolithography — the key process for making semiconductors. The furor was exacerbated by claims that construction of a lithography...
interestingengineering.com
