Self-Building Chips — As Easy As Microwave Meals

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.'"

Comments

This is Useful How?

[TinyEngineer10]

This is not all that different from 'conventional lithographic techniques' from the way I understand this article (albeit which does nto include very much detail at all)

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?

[JustinOpinion]

As another poster points out, the microwaves are being used as a heat source (not for patterning), instead of oven annealing. It turns out that a microwave can cause the material to assemble much faster than conventional oven annealing, which is pretty exciting.

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 (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 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.