Note: This question-and-answer blog post I did with Aki Fujimura, CEO of D2S and a member of the ESD Alliance Governing Council, first appeared on the SEMI website in May. It also kicked-off my Q&A blog post series with member company executives.
A change is underway in the manufacturing sector as the use of curvilinear shapes on photomasks grows, leading to the real possibility of curvilinear shapes in designs. It may just be the start of a revolution away from Manhattan or rectangular shapes to curvilinear shapes. Changing the physical design infrastructure to be curvilinear seems too daunting a task. Are curvilinear shapes in designs a real possibility?
Aki Fujimura
I turned to Aki Fujimura, CEO of D2S and a member of the ESD Alliance Governing Council, to further explain the shape of the future.
Fujimura: Manufactured masks and wafers are all curvilinear, even if the input CAD geometries are rectilinear (shown in Figure 1). It’s always been true that nature can’t make 90-degree turns, so sharp corners were always a matter of how closely you looked. These days, at the leading-edge nodes and their required resolutions, wafers and even masks are all visibly curvilinear as you can see in the graphic on the left in Figure 2.
Since the 1980s, both chip design and chip manufacturing systems have used axis-aligned rectangles, or “Manhattan” geometries, because 1) that was sufficient to design transistors and interconnect for the most part, and 2) CPU-based computer algorithms can be made much more efficient for Manhattan geometries. Curvilinear shapes can be piecewise linear polygons of some resolution, or spline-like formats that are curvilinear at any resolution, or specific curved patterns like circles and ovals.
Figure 1: All shapes on masks and wafers are curvilinear, even if the input geometries are Manhattan. Source: D2S
