Looking for an integrated post-tapeout flow

Integration is a feature we all look for in our electronic devices. Information readily available on our smart phones is integrated with web-based services and with our personal data on our home computer.  This interoperability that we take for granted is thanks to common software and hardware platforms that are shared by all the elements of this system. Platforms surround us everywhere in our daily lives – the specific model of the car we drive is built on a platform, the electrical systems in our house are on a platform: 110/220V with universal plugs. Platforms?! So I got curious and looked up a more formal definition on Wikipedia:

Platform technology is a term for technology that enables the creation of products and processes that support present or future development.

Why has the concept of platforms been on my mind? Because I hear it more and more often from engineers in the trenches of the post-tapeout flow – people who develop the data preparation sequences that ready their design for manufacturing. They say it is getting increasingly complicated to accommodate all the functional requirements and still meet the TAT (turn-around-time) requirements.  The 20nm node adds additional complexity to this flow – beyond retargeting, etch correction, fill insertion, insertion of assist features and the application of optical proximity correction– now decomposition-induced steps are required and replicate some of the steps for both layers.  Industry standards like the OASIS format enable the communication between independent standalone tools, but are not enough to enable extension in new functional areas and maintain a steady overall runtime performance. Users have to be familiar with all the features and conventions for each tool – not an efficient way to scale up an operation.

The oldest and most versatile platform in computational lithography is Calibre. It started with a powerful geometry processing engine and a hierarchical data base and is accessed through an integrated scripting environment using the Tcl-based  standard verification rule format (SVRF) and the Tcl verification format (TVF). As the requirements for making a design manufacturable with available lithography tools has grown, so has the scope of functionality available to lithographers and recipe developers. APIs have expanded the programming capabilities: the Calibre API provides access to the data base, the lithography API provides access to the simulation engine, the metrology API enables advanced programming of measurement site selection and characterization, the fracture API enables custom fracture (Figure 1). All of these functions let you both build data processing flows that meet manufacturing needs and encode your very own ideas for the most efficient data processing approach. The additional benefit of a unified platform is that it also enables the seamless interaction and integration of tools in a data processing flow. If you can cover the full flow within one platform, rather than transferring giant post-tapeout files between point tools, you will realize a much faster turn-around time.

Common workflow
Figure 1: All tools in the Calibre platform are programmed using the SVRF language and tcl extensions and can be customized via a number of APIs – maintaining a common and integrated workflow.

A platform like Calibre is uniformly used in both the physical verification of the design and in manufacturing, so that innovation entering the verification space flows freely over to the manufacturing side without rework and qualification. Examples include the smart fill applications and the decomposition and compliance checks for double-patterning (DP).

The benefits to using a unified software platform in the post-tapeout flow, illustrated in Figure 2, are also leveraged by the EDA vendor—our software developers use the common software architecture in the platform for very fast and efficient development of new tools and features. This reduces the response time to customer enhancement requests. New technology, like model-based fracture and self-aligned double patterning (SADP) decomposition, were rapidly prototyped based on that.

Calibre workflow
Figure 2: Benefit and scope of a platform solution and the support level provided by Calibre.  


A platform not only provides the integration and efficient operation at the work-flow level, but it also enables efficiency at the data-center level, considering the simultaneous and sequential execution of many different designs and computational tasks. The tapeout manufacturing system is a complex infrastructure of databases, planning, and tracking mechanisms to manage the entire operation. Common interfaces into the tools used –which are guaranteed by a platform solution–let you track data and information associated with each run and manage interactions and feedback across different jobs.  This leads, for example, to an improved utilization of the computer system overall as well as better demand and delivery forecasting. Operating a manufacturing system requires a different level of support than single tool solutions and the necessary infrastructure has evolved with the development of the components.

Once you start using a unified platform in your post-tapeout flow, you will see how the platform expands and grows. For today’s sub-nanometer technologies, a powerful and flexible platform for computational lithography is part of a successful business strategy.

Author biography

Dr. Steffen Schulze is the Product Management Director for the Mentor Graphics’ Calibre Semiconductor Solutions. He can be reached at [email protected].


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