November 29, 2018
Introduction
In the very early days of integrated circuit design, design rules were vastly simpler than they are today. In fact, back then, manual visual checking of the layout sufficed. As process technologies continued to shrink to smaller geometries, the relatively simple checks for spacing, pitch, overlap and other checks became too complex to analyze manually, opening the door for computer automation to be applied for performing the design rule checks. Design rule complexity is measured by the number of computation operations required to cover and verify the rule, if has grown faster with decrease of foundry process node.
Today’s complex process technologies require extensive checking that is well beyond simple geometric checks of the layout. These rules span lithographic, electrical, chemical and mechanical effects that all must be checked and in some cases, compensated for. The challenges in physical verification arise due to:
- Geometries that are smaller than the wavelength of light used in patterning
- An explosion in the number of rules and parameters that must be checked
- Rules that span multiple layers
- Proximity rules that are dependent on neighboring objects
- Chemical effects such as the need to introduce metal fill
- Electrical effects such as antenna and electromigration
- Growth in design density and complexity
Taken together, these challenges demand the need for a high performance, highly accurate physical verification (PV) solution.
Limitations in Current Hierarchical Physical Verification Solutions
Most of the well-known physical verification tools on the market today utilize hierarchical techniques to attack the problem. The rationale behind this approach is that once a cell has been checked, all other instantiations of that same cell in the design can be assumed to be good. In theory, this should deliver faster runtimes. But, with the advent of newer rules such as proximity effects, that assumption is no longer valid. A given cell may be identical to another cell, but their neighbors may be completely different. In a very regular design such as a memory array, the hierarchical approach can yield benefits, but in a typical complex digital logic design or analog mixed signal design, the hierarchical approach can yield much slower runtimes and suffer from accuracy problems. As a result, a hierarchical tool will often have to switch to flat mode to deliver the accuracy needed, but with severely degraded and unpredictable runtimes
POLYTEDA CLOUD offers an innovative, natively flat solution to physical verification that overcomes and surpasses the limitations of the hierarchical approach.
Introducing the One-Shot DRC Engine
The One-Shot DRC technology is a proprietary architectural innovation in DRC processing that is the heart of the PowerDRC/LVS engine, the foundation of POLYTEDA CLOUD’s cloud-based solution for physical verification, PVCLOUD. One-Shot delivers a natively flat solution to physical verification as opposed to the hierarchical solutions employed by most other PV tools.
One-Shot Processing Uses a Window to Check All Layers in the Window Simultaneously
One-Shot processing uses a window-based capability to verify a block of the layout, including all layers, and processesthe rules associated with them simultaneously. The windowing approach enables memory efficient processing and the size of the window can be controlled by the designer. Because the window size is known and performance per unit area is linear, runtimes are highly predictable. Runtime performance and capacity can be further accelerated by scaling to multiple CPUs. PVCLOUD will run on up to 128 CPUs in parallel to increase throughput and capacity.
DRC multi-CPU scalability with One-Shot Processing
Today’s process geometries pack more devices into a smaller area which leads to more devices moving into the proximity of the immediate area being analyzed. Because of this, nearest neighbor comparisons are becoming the norm. As the design size reduces, the requirement for checking for proximity effects does not scale with it since these effects are based on physics. Therefore, more rules and parameters are required leading to the need to process more checks and rules within a given area.
One-Shot processing is better suited than any hierarchical processing technology that handles a few layers at a time. The One-Shot DRC processing engine has a close to linear relational dependency between run time and input data size. Therefore, there is no need to rely on hierarchy to manage performance. The processing speed is directly proportional to the number of objects being processed and is constant for a given style of layout and process node. In other words, the performance is predictable.
The One-Shot technology also delivers higher accuracy than hierarchical approaches. Processing is not limited by factors such as the many complex rules that span hierarchical boundaries. Instead, One-Shot’s all-layers approach delivers the most accurate results.
Best Fit Uses for PVCLOUD with One-Shot Technology
PVCLOUD has been optimized to deliver performance and accuracy over a wide range of applications and process geometries for semiconductor design while delivering the cost-efficiencies of cloud-computing.
Process technologies supported include almost any CMOS, BiCMOS or other silicon-based process from microns down to 32nm. Ideal design applications include digital logic, analog mixed-signal, memory, silicon photonics, image sensors, rad-hard, and power management. POLYTEDA CLOUD is a good fit for many IoT designs that include analog mixed-signal and sensor technologies.
Fabless design teams and design services companies developing ASICs, IP, and custom chips or layout blocks can all benefit from the performance and cost-savings of utilizing POLYTEDA CLOUD as their primary physical verification solution. Foundries can also benefit by providing their customers with access to POLYTEDA CLOUD and using it to in-house for qualification and design acceptance.
Benefits of One-Shot Technology and PVCLOUD
The One-Shot technology makes up the core of PVCLOUD for cloud-based physical verification. PVCLOUD performs DRC, LVS, XOR, DIFF, FILL, RCX and text-based OPC operations – a full suite of physical verification capabilities. Within PVCLOUD the combination of One-Shot technology, multi-CPU processing and the PWRL language (a powerful rule language) deliver a complete cloud-based physical verification suite.
PVCLOUD Platform
The benefits of One-Shot and PVCLOUD include:
- Sign-off level accuracy
- Faster throughput of full-chip physical verification using One-Shot
- Predictable runtimes based on a linear relationship to the number of layout objects to be processed
- Scalable capacity and performance via multi-CPU parallel processing (currently proven with up to 128 CPUs)
- Faster creation and smaller rule decks using PWRL
- Eliminates need for investment in local servers and associated maintenance and support
- Design team is always using the latest version of PVCLOUD since it is hosted in the cloud
- Budget efficiency – immediately scale processing up or down based on budget and schedule
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