Feb 04, 2014

Smoother IP to SoC Prototyping

posted by Bryon Moyer

Synopsys recently announced their HAPS DX (Developer eXpress) product, and the story surrounding that release spoke to many of the things that Synopsys sees as good in their prototyping solution. But a few questions clarified that many of those things have already been available in the existing HAPS offerings. So what’s the key new thing that HAPS DX enables?

Turns out it has to do with the distinction between designing IP and designing an SoC. And this is actually a theme I’m seeing in other contexts as well.

IP started out as mini-designs that were built with the same tools as a full-up chip (or FPGA). Frankly, for a lot of IP companies, the products on the shelf probably wouldn’t have worked for any arbitrary application: they’d need tweaking first. So these products were largely a way to get consulting contracts that would modify the shrunk-wrap IP into something that included all the specifics the client needed.

Even then, folks looked askance at IP, preferring to do it themselves for NIH and control reasons as well as due to the illusion that inside folks were free (or at least already paid for). IP company survival was not a given.

Today it’s assumed that any designer of an SoC will spend a lot of effort (and money) integrating IP; it’s no longer cool to invent a new wheel. But this has changed the nature of design. While full chip design used to be just a bigger version of the process used to design IP, now IP is more about low-level gate design and SoCs are more about assembly (with lower-level design where absolutely necessary).

So now there’s more of a break between where the IP design stops and the SoC design starts, and tools are starting to reflect the challenges of this change of methodology. And that’s the main benefit to the HAPS DX product: it allows for a more seamless transition from IP design to SoC design.

Before, one person might design and verify the IP, and the user then started from scratch, redoing much of the work that the original IP designer did when prototyping. HAPS DX, by contrast, is supposed to help bridge that gap, allowing a more seamless move from IP to SoC with data generated in the IP phase pushed forward for re-use when that IP is integrated.

You can see more of what they’re saying in their announcement.

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Feb 03, 2014

Tree Frogs Help Graphene Grow

posted by Bryon Moyer

Growing high-quality graphene for use on wafers is hard. Chemical vapor deposition (CVD) is the favored approach, but no one has perfected the ability to grow it directly onto the oxide surface of a wafer.

It’s much easier to grow it on a sheet of copper and then transfer it over. But that transfer step can be tricky, and copper isn’t a perfectly uniform, crystalline material either. So defects can easily result.

One obvious trick might be to put copper on the oxide, grow the graphene on that, and then etch the copper away, leaving the graphene on the oxide surface. This technically can work, but the graphene tends to lift off the surface before it can be secured in place.

So… it would be useful to find a way to hold that graphene layer before it’s baked down. And if you were looking for a way to get something to adhere to a surface, where would you look in nature for ideas?

Why, tree frogs, of course!

Tree_frog_red.jpg

 

Image courtesy W.A. Djatmiko (Wikipedia)

 

It turns out that tree frogs stay attached to underwater leaves thanks to nano-sized bubbles and capillary bridges between leaf and foot. Some beetles do a similar trick.

 

Well, this idea has now been transferred to graphene. Prior to laying down the copper, the wafer surface is treated with nitrogen plasma. Copper is then sputtered on and CVD deposits the carbon. The carbon is then etched, and, during that process, nano-bubbles form, creating capillary bridges. These hold the graphene in place as the copper disappears.

 

A final bake step secures the graphene to the wafer and eliminates the bubbles and capillaries.

 

You can read more about this in their paper, but it’s behind a paywall.

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Jan 30, 2014

Micro-Windmill Surprise

posted by Bryon Moyer

It’s one of those good problems.

You’ve been doing some exploratory MEMS work. Your main focus is biomedical – implants for dealing with prostate cancer. Silicon is too brittle, so you do some exploration with a foundry to experiment with different structures and materials. A nickel alloy looks interesting – more forgiving than silicon (at the expense of a lower Young’s modulus). And there’s some extra space on the die.

One a whim, you and a co-researcher half-jokingly discuss putting a windmill on there. During the discussion, she is watching her daughter play with a pinwheel. Inspiration strikes, and overnight she completes a design that goes onto the die. Despite the auspicious name of the MEMS company you’re working with, WinMEMS (one letter away from WindMEMS), you think it probably won’t work.

Only… it does work. Not only does it function as expected, but someone accidentally drops some on the ground – and they still work.

What do you do now?

Most academics would publish. But here’s the deal: you’ve been burned before by companies that have leveraged your work with nothing coming back to you. And universities don’t like this either. So you don’t publish: you patent. And you delay telling the world about it for a couple months until the lawyers relax.

And then you issue a press release.

And then you give up any hope of getting any work done until the phone stops ringing.

This has been life for Dr. Jung-chih Chiao and Dr. Smitha Rao at the University of Texas in Arlington. They’ve been totally sidetracked by the surprising (to him) success of this little side project.

Because no paper has been published, there’s no end of questions about how they achieved their results. There were some pictures, but no details, especially about such critical aspects as, how do they convert the motion into electrical energy? I discussed that with Dr. Chiao, but apparently I didn’t ply him with enough drink to get him to give up the secret. So it remains a secret.

I was actually the 20th person to talk to him. They’ve been bombarded not just with press, but with companies wanting in on the action. They’re not just calling him; they’re calling colleagues as well. So they’re remaining tight-lipped for now.

He’s pretty confident in the design that they’ve done – they’ve aimed for simplicity in order to ensure reliability, but there are still issues to be solved. The two main ones are figuring out how to keep dust from mucking up the works and new ways of countering stiction.

They will be looking for commercialization partners. He sees the university’s role as solving the basic physics, including the two problems just mentioned. There will be other changes before anything goes into full production, but he sees the partner company doing that work. And he’s confident that this thing is manufacturable. Depending on funding, he sees this as being completed on about a one-year horizon.

After his work on this has been completed, he’s looking at possibly putting together a simulation tool. Depending on where you want to place the micro-windmills – cars, bridges, wherever – you may want to optimize the design. A simulation tool would make that possible.

For right now, it’s more basic: the phone needs to quiet down so they can get back to doing actual research.

And we’re still going to have to wait to figure out how this all works.

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