ABSTRACT
In this chapter we will show and explain the current status of commercial available tools, which are needed to bring a 3D system from the idea to a manufactured system. Depending on the design complexity, existing 2D tools can directly be used to design parts of the 3D system. In some cases add-ons for the 2D tools are required, and for complex designs new tools are needed.
Similar to the 2D case, a 3D design flow can be divided into a construction phase and a corresponding verification phase as depicted in Figure 14.1. On the left side of Figure 14.1 the construction or design phase is shown, whereas the verification phase is shown on the left side. Design flow for 3D system development. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315214306/963a4f3b-ca0a-40a0-956b-53cf3973ad6f/content/fig14_1.tif"/>
If we look at these two phases, we can divide both into two major sections—a 3D and a 2D section. If the design reaches the 2D section, the 3D system is broken into classical 2D (sub-) systems (chips, interposers) and corresponding system integration elements between them (e.g., balls in Figure 14.2). Thus, the goal of the 3D design is to structure the 3D system into 2D (sub-) systems and some connecting elements. Tools that divide the 3D system into the 2D systems must consider different requirements such as timing, temperature, and fabrication costs. 3D system can be divided into “classical” 2D systems. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315214306/963a4f3b-ca0a-40a0-956b-53cf3973ad6f/content/fig14_2.tif"/>
System-level design exploration should take place at a very early design stage. Most of the required interaction should be done within the 3D design space. On the other hand, to get a detailed evaluation of a chosen design option, the 2D tools can be involved as well. But this kind of interaction should be limited to a minimum as it is often time-consuming.
Most 3D floorplanning approaches fall into the latter category. Examples are 3D-STAF [1] or the floorplanning approach described by Quirring et al. in [2]. Every new floorplan directly affects the layout of each sub-component (here tier). An evaluation requires the calculation of a cost function, which often uses 2D tools for calculation (e.g., routing congestion estimation) increasing the coupling with the 2D design phase. The dependency becomes even clearer when specific architectural decisions need to be made. For example, 3D network-on-chip (NOC) design approaches as described in [3,4] require more detailed layout information as floorplanning itself can offer.
For verification, we separate into 2D and 3D as well. In the 2D section the classical 2D system verification steps take place, such as Design Rule Check (DRC), Layout versus Schematic (LVS), parasitic extraction, timing verification, and optical proximity correction (OPC).
312 313These verification steps can be directly integrated into established flows for the 2D chips. Only smaller adoptions to new technologies are required (e.g., rule decks for TSVs or interposers). If we look at 3D, the tools must address the same verification steps as in 2D, but now focused on the interaction between the different (sub-) systems. For example, the 3D DRC must check if the pads between different dies are aligned (see Figure 14.3). 3D verification (right) requires adopted “classical” verification steps and the consideration of the (sub-) systems interactions (e.g., pad alignment). https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315214306/963a4f3b-ca0a-40a0-956b-53cf3973ad6f/content/fig14_3.tif"/>
