There’s no doubt that FinFET technologies have been very appealing. With FinFETs being up to 37% faster while using less than half the dynamic power than planar transistors, they have been a ‘no brainer’ to adopt and the industry has embraced them. To that extent, in a recent survey of Synopsys users, more than a third of those who responded plan to use FinFET technologies on their next chip.
In the last blog post I profiled the use of the symbolic editor for rapid digital cell layout.
In this post we will tackle analog cell layout and show some more of the symbolic editor features that enable analog layout engineers to complete their layout in minutes versus hours.
As with the digital cell layout, the engineer can take advantage of the symbolic editor’s ability to define multiple P and N row pairs as shown in Figure 1.
In Custom Compiler Layout Assistants – part 1 we profiled the use of the symbolic editor and how it makes placing devices that need to be in a specific interdigitated pattern like for example a differential pair very easy. With no constraints to enter, no code to write, layout is done in minutes versus hours.
In the blog Custom Compiler In-Design Assistants Part 2, I outlined how we can use StarRC to report capacitances on critical nets in the layout even when the design is still in flux and not completely LVS clean. In addition to capacitance reports we also showed resistance reporting which is critical for FinFET based layouts. At advanced nodes, the impact of parasitics, electro-migration (EM) and restricted design rules, drive critical layout choices. Interconnect that does not meet resistance or EM criteria and unbalanced capacitances on matched nets, can and often does adversely impact layout schedules. So the earlier in the layout phase, the layout engineer can address these issues, the sooner he or she can close the design.
On line Design Rule Checking (DRC) is nothing new. The technology has been in use for years in a variety of different layout editors and yet nearly every Layout engineer has a love / hate relationship with it. Why? Well it really comes down to the use model and the responsiveness of the application.
In the last blog I detailed the symbolic editor layout assistant and showed how the layout engineer can make simple graphical choices of how the layout needs to look and then have the placement taken care of by a placement engine. In this post I will outline another layout assistant the router. The routing task is one that absolutely screams out for an automated approach however past efforts have required a great deal of text-based constraints to get anything near to what you really want.
In the last of blog we outlined the kind of tool that the layout engineer needs in order to get a good placement that delivers robust working silicon within the confines of the FinFET process. We concluded that a guided / interactive approach that is fast and easy to refine such that you do get the result you want is the way to go.
What is Electro-migration and why is it something we should care about?
So, what tools do we have in our FinFET toolbox that can help layout engineers manage the complexity that FinFETs inherently bring?
Graham Etchells