Virtual Fabrication: Not just for fabs. Fabless companies can benefit from more visibility into process technology

Ever since I started talking about Virtual Fabrication I have mostly looked at it from the manufacturers’ perspective, where it has obvious benefits to develop and model new process technology. But what about the fabless design concept and indeed even the semiconductor IP world that has spawned from it as well? It seems that Virtual Fabrication could be very effective to gain confidence in the fabrication of design by a fabless company, before it sees the actual foundry. Just think about this and in the meanwhile let’s briefly reflect on the evolution of fabless design concept.

Technical perspective – 30 years ago, the major chip design companies were IDMs, and therefore had their own internal foundries. The technologies were developed behind closed doors and more proprietary. A chip design’s journey through the captive foundry next door was easier, although the design and fabrication still happened separately. With an increasing number of players, fabrication technology started opening up for designs from outside companies.

Cost perspective – Although it feels nice to have proprietary technologies and designs with complete ownership, it became financially unfeasible when the large capital cost of foundry was unrecoverable by only in-house design and manufacturing. Economics being a bigger challenge, many semiconductor companies slowly transitioned towards being fabless, and new players emerged as a result of a lower barrier to entry (i.e. you could start a chip company without the capital burden of manufacturing it yourself). Of course, technology scaling was chugging along at full throttle, which helped paved the path for fabless designs.

Market perspective – As the fabless concept gathered momentum, numerous small and large players came into existence across the world. This created large demand for contract, on-demand semiconductor design and fabrication. It became a natural progression for the semiconductor ecosystem to have pure-play foundries that could serve multiple fabless design houses across the world.

Although a fabless design flow has become robust with the significant available technology information available from the foundries (PDKs), and through the general maturity of the technology process, most designs still needs several cycles through the foundry in order to meet product targets and begin high-volume manufacturing. So, why not perform those cycles in a ‘fabless’ fabrication environment until the design becomes perfect for fabrication? One may argue that this concept also will need time to mature, but the emergence of a true Virtual Fabrication Platform, such as Coventor’sSEMulator3D, would seem to offer enough intelligence to understand and predictively model today’s newest and most advanced technologies.

Why is Virtual Fabrication so important for fabless designers? Let’s consider some of the recent technological complexities that pose the biggest challenges to comprehend for their fabrication. Recently, there have been many structural changes in technology processes that can lead a design through different paths and hence makes it necessary for the designers to make informed decisions during the design phase. The designers need to have confidence in any number of technologies that a design is going to adopt, such as FinFET on SOI, FinFET on Bulk, Gate First, Gate Last, FDSOI and several other variations. And the choice of a foundry can make or break a fabless company as a particular technology can have huge implications on the design IP. Leaving that decision until final fabrication in the foundry can be hugely expensive, as well as being time and effort consuming. What if we can get to that decision quickly at the design stage through Virtual Fabrication? By using the Virtual Fabrication technique, the designers can look at what’s going on inside a foundry without owning the foundry, or even paying the price for prototypes. Design teams can perform detailed modeling of their IP in the targeted technology using a virtual environment. After quick, inexpensive virtual cycles, the design can be delivered the foundry of choice with confidence for high-yield fabrication.

So, my open question to fabless design community is – why not use Virtual Fabrication to make a chip design perfect for fabrication? This is exactly the same method as is used to make designs perfect for functionality, timing, area and power through design flows involving several design steps, simulations, verifications, corner analyses and variation analysis.

My own belief is that in today’s semiconductor technological environment with increasing process complexities and foundry differentiation, Virtual Fabrication can provide significant benefits to the fabless design world by shortening the design cycle prior to fabrication, saving cost, time and effort, and increasing confidence in fabrication yield. However, I would like to hear opinions from the industry experts. Comments are welcome!

At this time, it’s an opportunity to know more about Virtual Fabrication and SEMulator3D at Coventor’s booth # 718 at the 51[SUP]st[/SUP] DAC. Do visit and let’s know what you think about Virtual Fabrication.

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