Reimagining 3D IC Design: From Architecture to Signoff

By Keith Felton, Andras Vass-Varnai and Todd Burkholder, Siemens EDA

The semiconductor industry is undergoing a fundamental transformation. Heterogeneous integration, the practice of combining multiple chiplets and specialized components into a single advanced packaging platform, has emerged as a powerful alternative to traditional monolithic chip design. This shift promises superior performance, improved power efficiency, greater flexibility, and reduced manufacturing costs. Yet realizing these benefits requires a complete reimagining of how semiconductor companies design, verify, and manufacture complex systems.

Siemens Innovator3D IC™ product family addresses this challenge with a unified design platform that spans the entire product lifecycle, from early architectural exploration through final manufacturing signoff. Rather than relying on disconnected point tools that force teams to work in silos, the platform creates a continuous digital thread connecting silicon designers, package architects, verification engineers, and reliability specialists around a common 3D digital twin.

The Case for Heterogeneous Integration

The traditional approach to semiconductor design centered on monolithic architectures, where all functionality resided on a single die. This model worked well for decades, but it increasingly struggles to meet the silicon scaling demands of artificial intelligence, hyperscale computing, and high-performance applications. These workloads require combinations of specialized processors, high-bandwidth memory, and custom accelerators that are difficult to integrate efficiently on a single piece of silicon due to reticle size limits and yield challenges.

Heterogeneous integration solves this problem by allowing engineers to assemble pre-designed, custom, or third-party chiplets onto high-performance interposers and advanced package substrates. This modular approach enables companies to mix and match components optimized for specific functions, rather than forcing all logic into a single die at a single process node. The results are systems that deliver better performance per watt, scale more flexibly as requirements change, and cost less to manufacture at volume.

However, existing design tools were built for single-die devices and cannot adequately handle the complexity of 2.5D and 3D IC designs. A new methodology is required, one that takes a system-centric view from initial planning through final sign-off. This is where the Innovator3D IC product family enters the picture.

Building the Digital Twin Foundation

At the heart of the Innovator3D IC platform is the 3D digital twin, a comprehensive virtual representation of the entire device assembly. Creating this twin begins with aggregating design data from multiple sources to construct a full-system model. This model drives the creation of interfaces and bump arrays for chiplets, bridges, interposers, and substrates, resulting in a single authoritative source of system connectivity.

This task is more complex than it sounds. Heterogeneous designs can contain over 50 million total pins and hundreds of thousands of connections. Traditional spreadsheet-based approaches, once adequate for smaller designs, become error-prone and unmanageable at this scale. The industry is developing standardized data formats, such as IEEE 3Dblox, OCP CDX, and JEDEC JEP30 Part Model, to simplify integration and improve interoperability. These standards promote compatibility between chiplets and streamline the exchange of comprehensive component information.

The digital twin serves as the foundation linking every stage of development. It enables true system-level technology co-optimization (STCO) across silicon, interposers, package substrates, and system PCBs. Because all teams reference the same digital representation throughout the design process, design intent remains consistent and integration surprises are minimized. Innovator3D IC Integrator supports this concept with a comprehensive design cockpit spanning the explore, design, analysis, reliability, and test domains.

Explore: Architectural Options

Before implementation begins, architects must determine which integration strategy best satisfies power, performance, area, cost, quality, manufacturability, and test objectives. The “Explore” domain within Innovator3D IC Integrator enables silicon designers, package architects, and system designers to collaborate on early planning and feasibility analysis using a common digital twin.

Leveraging predictive modeling and machine learning-assisted design-space exploration, engineering teams can evaluate multiple system-in-package scenarios before committing resources to physical implementation. These evaluations include chiplet partitioning studies, package technology comparisons, floorplanning assessments, routability analyses, power delivery investigations, thermal feasibility studies, signal integrity assessments, and test planning activities.

The key advantage is that all these activities occur using the same digital twin that will ultimately drive implementation and sign-off. This continuity ensures that design intent established during exploration carries through to the final product, reducing downstream rework and accelerating convergence toward an optimal solution.

Design: Implementing the Selected Architecture

Once an optimal architecture has been identified, the focus shifts to physical implementation. The “Design” domain provides a unified environment for chiplet, interposer, and advanced package implementation. This stage requires translating system intent into a manufacturable multi-die design while preserving the connectivity, performance, and reliability objectives established earlier.

The implementation process begins with interface and bump array construction. Many package designs exhibit repeatable patterns that can be represented as parameterized objects. Rather than modeling each device as a flat entity, designers can represent them as hierarchical building blocks with topological pin regions defined using formulas, regular expressions, and design attribute tokens. This approach dramatically accelerates design creation and enables rapid iteration.

System-level netlist creation and validation represents another critical step. With designs containing millions of connections, language-based design approaches using Verilog RTL and proper bus notation prove far more efficient and reliable than bit-by-bit spreadsheet definitions. This enables designers to manage the explosion of die-to-die connections while ensuring that interface definitions, bump assignments, and connectivity remain synchronized as development progresses.

Bridge and interposer instantiation follows naturally from connectivity. Rather than designing these components from scratch, the most efficient approach derives them as functions of the devices they interconnect, leveraging the already-verified netlist. Innovator3D IC Integrator uniquely represents the entire system within a single environment, from early hierarchical device planning through final sign-off.

Logic and memory devices require high-speed, high-bandwidth interfaces, necessitating close proximity often achieved through silicon bridge devices. Most multi-device packages also require substrate stiffeners, seal rings, thermal interface materials, and heat spreaders for thermal management and encapsulation. These mechanical objects occupy real estate and require clearance considerations, directly impacting placement strategies.

Connectivity planning across substrate boundaries typically focuses on high-performance die-to-die interfaces and die-to-package connections. Enabling effective STCO requires new levels of intelligence in design tools. Innovator3D IC Integrator employs machine learning algorithms to concurrently optimize connectivity and device pin and bump assignments across all hierarchy levels, balancing resources across all domains to achieve high-performance, cost-effective solutions in the shortest time.

Power delivery network (PDN) prototyping and predictive analysis follow connectivity optimization. Increased power and performance demands in semiconductor packages have escalated power delivery challenges, making early analysis critical. Designers must prototype PDNs to provide sufficient and stable power while managing spatial constraints in dense designs. After prototyping, designers analyze the PDN for suitability, identifying significant DC-drop issues early to prevent costly changes. Once DC-drop requirements are met, the focus shifts to metal density across each layer, with automatic addition of user-defined metal areas to balance layers and prevent substrate warpage.

Analysis: Multiphysics Verification

As heterogeneous systems grow in complexity, traditional point-tool analysis methodologies struggle to capture interactions between silicon, interposers, bridge dies, redistribution layers, and advanced package structures. Innovator3D IC Integrator extends beyond physical planning by providing a unified analysis framework operating directly from the digital twin.

The “Analysis” domain supports end-to-end electrical and mechanical verification across the complete assembly, enabling signal integrity, power integrity, and IR-drop as well as thermal and thermo-mechanical evaluation from early architectural studies through final sign-off. Engineers can analyze full or partial implementations using intermediate package databases long before final design completion, identifying potential bottlenecks, voltage droop concerns, routing limitations, channel degradation issues, and reliability concerns while architectural changes remain relatively inexpensive.

By combining technologies such as HyperLynx™, mPower™, and advanced extraction solutions within a common workflow, engineers gain continuous visibility into electrical performance across all design domains. Automated testbench creation and coordinated multidomain analysis help shorten design cycles while improving confidence in sign-off readiness.

Modern advanced packages must also meet stringent thermal, mechanical, and long-term reliability requirements. Historically, thermal and thermo-mechanical analysis occurred after substantial design completion, introducing significant risk because package architecture decisions directly influence thermal behavior, warpage, stress distribution, and long-term reliability.

Innovator3D IC product family integrates thermal and mechanical verification directly into the design cockpit, enabling architects and package designers to initiate and evaluate multiphysics simulations throughout development. Through integration with Calibre® 3DThermal, Calibre 3DStress, Simcenter™ Flotherm, and Simcenter Simlab, users can assess thermal performance, package warpage, mechanical stress, vibration effects, and manufacturing-induced stresses across the entire assembly.

Because reliability analysis connects to the same digital twin used for planning and implementation, teams can evaluate design tradeoffs earlier and establish a common digital thread extending from architecture exploration through manufacturing sign-off. The shared digital twin allows package architects, silicon teams, and reliability specialists to evaluate tradeoffs using a unified representation of the system.

Test: Planning for Manufacturability and Yield

Complex multi-die assemblies must be optimized for manufacturing test, debug, repair, and long-term yield. The “Test” domain of Innovator3D IC leverages IEEE 1838-based multi-die test methodologies together with thermal-aware test planning to ensure that high-activity test patterns do not introduce excessive power or thermal stress during manufacturing. By connecting DFT planning, thermal analysis, and validation within the same digital twin environment, engineering teams can improve fault coverage, accelerate test development, and reduce the risk of yield loss and latent reliability issues.

Accelerating Time to Market

The future of heterogeneous integration requires a design methodology extending far beyond physical implementation. Engineering organizations need a platform capable of supporting architectural exploration, digital-twin creation, physical implementation, multiphysics verification, reliability assessment, and sign-off within a unified environment.

Innovator3D IC Integrator delivers this capability through a comprehensive design cockpit spanning Explore, Design, Analysis, Reliability, and Test domains. Using a common 3D digital twin and continuous digital thread, teams can evaluate architectural alternatives, optimize connectivity, perform predictive multiphysics analysis, assess product reliability, and validate design readiness long before manufacturing.

By unifying traditionally disconnected workflows and enabling STCO, Innovator3D IC Integrator helps design teams reduce iterations, improve predictability, and accelerate time-to-market. The platform allows engineering organizations to confidently deliver the next generation of advanced heterogeneous systems by maintaining a single source of truth throughout the entire design lifecycle. In an industry where time-to-market directly translates to competitive advantage, this unified approach represents a fundamental shift in how complex semiconductor systems are developed.

To learn more on how to improve your 3D IC flow, please check out the new whitepapers from Siemens: From architecture exploration to signoff: Accelerating the 3D IC lifecycle and Reliability in 3D IC design: A proactive multi-physics approach.

Keith Felton is the Principle Technical Product Marketing Manager for the Innovator3D IC product family at Siemens DISW in Marlborough, MA. Working extensively in IC package design since the late 1980s, Keith drove the launch of the industry’s first dedicated system-in-package design solution in the early 2000s and led the team that launched Siemens OSAT Alliance program. His current focus includes driving the strategy and direction for Siemens multi-substrate prototyping, design, and verification solution for high-density advanced packaging.

Andras Vass-Varnai is a 3D IC reliability solution engineer at Siemens EDA. Andras is dedicated to contributing to the development of a novel 3D IC package toolchain, leveraging his experience in thermal and reliability engineering. His main areas of interest include thermal management of electronic systems, advanced applications of thermal transient testing and modeling, semiconductor packaging, characterization of TIM materials, and reliability testing of semiconductor devices. Andras Vass-Varnai obtained his MSc and PhD degrees in Electrical Engineering from the Budapest University of Technology and Economics.

Todd Burkholder is a Senior Editor at Siemens DISW. For over 25 years, he has worked as editor, author, and ghost writer with internal and external customers to create print and digital content across a broad range of EDA technologies. Todd began his career in marketing for high-technology and other industries in 1992 after earning a Bachelor of Science at Portland State University and a Master of Science degree from the University of Arizona.

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