Self-Building Chips — As Easy As Microwave Meals 51
nk497 writes "Canadian researchers have found a way to speed up self-assembling chips — by using microwaves instead of traditional ovens. Self-assembly is seen as key to enabling nanotechnology, but until now the block co-polymer method, which directs nanomaterials to create moulds and then fills them in with a target material, was too slow to be useful. 'By using microwaves, we have dramatically decreased the cooking time for a specific molecular self-assembly process used to assemble block co-polymers, and have now made it a viable alternative to the conventional lithography process for use in patterning semi-conductors,' the researchers said. The technique could make the technology a viable alternative to conventional lithography for chip production. 'We've got the process — the next step is to exploit it to make something useful.'"
Anonymous Coward (Score:1, Informative)
Microwave: Grey, bland, dry, rubbery.
Traditional: Golden brown, tastier, juicy, crisp in the outside - tender in the inside.
There's no comparison.
This is Useful How? (Score:4, Informative)
Traditionally the photoresist which is being patterned is either having bonds broken to let exposed areas be dissolved away, or bonds made to keep the exposed areas in following steps. At the end of the day you're shining radiation on a substrate to make a pattern.
Here is seems to me is they're using block co-polymers to assemble between different configurations - a soluble and insoluble one I imagine? At the end of the day they're still using the idea as traditional lithography. Why investigate this method when there's wavelength limitations that are currently hit I have no idea.
Microwaves are sitting at a higher wavelength than UV/extreme UV which is in use today so I don't see this being useful for patterning for semiconductors. Perhaps if it's cheaper and more compatible I could see this put into lab-on-a-chip style fab methods or something else...
Re:This is Useful How? (Score:3, Informative)
s/higher/longer
And I'm no expert, but I think the microwaves are just used as a heat source to cure the material so their wavelength is immaterial. In TFA it says they're being used to replace "old-fashioned convective cookers".
Re:This is Useful How? (Score:4, Informative)
Via wikipedia i found an article stating 10nm is within reach for the method.
As to what the actual method is in details i'm not much wiser. But supposedly it's supposed to be simpler and allow smaller features than used today.
Self assembly? (Score:3, Informative)
TFA doesn't have much detail, in fact it doesn't have much of anything. I've even posted it below. What I was missing was an explanation for the "self assembling" claim. I had to go to Wikipedia [wikipedia.org]. I think the article submitter could have added that as a courtesy.
TFA:
Re:This is Useful How? (Score:5, Informative)
As for the "Why use self-assembly for lithography?" the basic idea is this: Conventional optical lithography is limited by the diffraction of light (as you mention). So for typical visible-light optical schemes, the best you can do is pattern features on the order of ~100 nm (using a bunch of tricks you can push a bit below this, which the semiconductor industry has done with fantastic results). In self-assembly, you design molecules that spontaneously form nanostructures of a well-defined size. So instead of enforcing a particular size-scale using light and patterning masks (top-down fabrication), you design the required size-scale into the molecules themselves (bottom-up fabrication).
In the work described in TFA, they were using block-copolymers, which are polymers (long chain-like molecules) that are have two chemically-distinct "blocks". So one half of the chain is of one kind of material, and the other half of the chain is another type of material. Like so:
AAAAAAAAAAAAAAAAA-BBBBBBBBBBBBBBBBBBBB
Because the "A" and "B" subunits don't like each other (they are sufficiently chemically distinct), they want to separate from one another (like oil and water not mixing). But because they are bound to one another using a covalent bond (the "-" in my diagram), they can't fully separate, and instead form nano-structures with a size-scale dictated by the length of the A and B blocks. So you can control the size using the lengths of the blocks, control the segregation using the chemistry of the two blocks, and control the morphology [nyu.edu] (the structures that form) using the ratio of the A block length to the B block length.
This process is fantastic at making well-defined structures at the nano-scale (down to 10 nm has been demonstrated; down to 5 nm seems do-able). However one still has to control the positioning of these structures. So a lot of work has gone into combining self-assembly with conventional photo-lithography. The conventional lithography defines the long-range registry and pattern; the self-assembly lets you fill in that pattern with ultra-small structures. In case you think this is all theoretical, Toshiba recently announced [slashdot.org] a working prototype hard-drive with magnetic dots made using these techniques.
Disclaimer: Part of my research is in this area, so I may be biased towards thinking this is cool/novel/useful.
Re:This is Useful How? (Score:4, Informative)
Are these co-polymers being use as an organic electronic material say in OLEDS or are they designed so that they have a specific configuration to essentially after assembling they are in the pattern you want them to be?
The dream is to have the block-copolymer blocks be functional. So, say one block is the donor and one the acceptor in an organic photovoltaic. Or the blocks form an OLED as you suggest. Or one block has a sensing element and the other block acts as electrode contacts. Or one block has reaction centers that can be metallized to generate wires.
The current state of the art is more primitive, with the assembled block-copolymer being used as a resist, since the two blocks will have different etch contrast. So in the case of the Toshiba work (Hitachi is working on something similar) the block-copolymer nano-dot pattern was used as a resist to etch into a magnetic layer and thus form magnetic nano-dots with a much higher area-density than could be done with conventional optical lithography (or something similar to that: they have not released full details). We're still not at the stage where we can build something as complex as a transistor using block-copolymers as the resist(s), but we're getting there.
are they designed so that they have a specific configuration to essentially after assembling they are in the pattern you want them to be?
Originally the hype about self-assembly was that the molecules would spontaneously form the devices you want ("Pour the components together in a beaker and a computer pops out!"). I think the field is getting more realistic now, and accepting that self-assembly has to be coupled with other techniques (such as optical lithography to control the larger-scale positioning, or annealing tricks, as in TFA, to direct the assembly) to create fully-functional devices. But self-assembly can still provide a level of nano-control and cost savings compared to more laborious techniques.
Re:This is Useful How? (Score:4, Informative)
Fast Assembly of Ordered Block Copolymer Nanostructures through Microwave Annealing [acs.org] Xiaojiang Zhang, Kenneth D. Harris, Nathanael L. Y. Wu, Jeffrey N. Murphy, and Jillian M. Buriak, ACS Nano, Article ASAP DOI: 10.1021/nn102387c [doi.org].
Here is the abstract:
Re:This is Useful How? (Score:3, Informative)
(rohtua ht4 eht m'i)
(oops... didn't mean to do that last one anon.)