Chiplets: The Modular Approach to Design

A chiplet is a smaller, functional block or die that performs a specific task — such as CPU, GPU, or memory processing — integrated together on a single package to form a complete system.
Instead of building one large, complex monolithic die, designers can assemble multiple chiplets like Lego blocks, offering:

• Lower manufacturing cost
  
  

• Better yield rates
  
  

• Design reusability
  
  

• Faster time-to-market

Examples include:

• AMD’s Ryzen and EPYC processors built with multiple chiplets for cores and I/O.
  
  

• Intel’s Foveros and EMIB technologies enabling heterogeneous integration.

3D ICs: The Vertical Revolution

3D Integrated Circuits (3D ICs) take integration to another level — literally. Here, multiple dies are stacked vertically using Through-Silicon Vias (TSVs) or micro-bumps, allowing shorter interconnect paths and higher data bandwidth between layers.

This vertical stacking enables:

• High performance and low latency
  
  

• Smaller form factor
  
  

• Lower power consumption
  
  

• Better functionality per unit area
  
  

3. How Chiplets and 3D ICs Are Transforming Physical Design

The introduction of chiplets and 3D ICs has revolutionized the physical design flow. Traditional flat design methodologies no longer apply — engineers must now consider multi-die, multi-layer, and thermal-aware design challenges.

Here’s how these technologies are reshaping every aspect of physical design:

a. Floorplanning Becomes System-Level

In traditional design, floorplanning focuses on a single die layout.

 In chiplet and 3D IC design, system-level floorplanning determines:

• Placement of each die or chiplet
  
  

• Inter-die connectivity
  
  

• Power and thermal distribution
  
  

• Signal and clock integrity

EDA tools such as Cadence Integrity 3D-IC and Synopsys 3DIC Compiler are now enabling multi-die co-design and optimization.

b. Interconnect Planning and Die Partitioning

In a chiplet ecosystem, data transfer between dies is crucial. Engineers must define:

• High-speed interconnect standards (like UCIe, AIB, or BoW)
  
  

• Die-to-die routing optimization
  
  

• Partitioning logic between dies based on functionality, latency, and power needs

This adds a new dimension to placement, routing, and verification strategies.

c. Thermal and Power Management

Stacking dies in 3D structures increases thermal density, making heat dissipation one of the biggest challenges.

 Designers now use thermal-aware placement and advanced cooling solutions (liquidcooling, microchannels) to prevent hotspots.

Power delivery networks (PDNs) must also be redesigned to manage vertical power flow and reduce IR drop.

d. Signal Integrity and Timing Closure

As interconnect paths shorten and layer-to-layer communication increases, signal integrity, crosstalk, and timing closure become more complex.

EDA tools must handle multi-die timing analysis, ensuring that all layers operate synchronously without introducing delay or skew.

e. Verification Complexity

Verification for 3D ICs and chiplets is far more challenging than for traditional SoCs.
Physical verification now includes:

• 3D DRC (Design Rule Check)
  
  

• Layout vs. Schematic (LVS) checks across dies
  
  

• Thermal and mechanical stress analysis
  
  

• Power intent verification
  
  

EDA vendors are actively integrating AI and automation to manage this verification complexity.

4. Advantages of Chiplets and 3D ICs in Modern Design

These benefits make chiplets and 3D ICs vital for future applications such as:

• AI accelerators and HPC chips
  
  

• 5G baseband processors
  
  

• Autonomous vehicle SoCs
  
  

• Edge computing systems

5. The Role of EDA Tools in 3D IC and Chiplet-Based Design

EDA companies are leading the transition toward multi-die design. Some key innovations include:

• Synopsys 3DIC Compiler: Offers unified design, analysis, and verification for multi-die systems.
  
  

• Cadence Integrity 3D-IC Platform: Enables full system co-design from packaging to silicon.
  
  

• Mentor Xpedition Substrate Integrator (SI): Facilitates planning for advanced packaging.
  
  

• OpenROAD / Open3DFlow: Open-source initiatives bringing 3D IC design education to universities.
  
  

These tools integrate AI-based optimization, cloud scalability, and cross-domain simulation to make 3D design workflows more efficient and collaborative.

6. Challenges in Physical Design for Chiplets and 3D ICs

Despite their advantages, engineers face several hurdles in adopting these technologies:

1. Thermal management — Stacked dies increase power density.
   
   

2. Testing and yield — Testing stacked dies individually and together is complex.
   
   

3. Design ecosystem fragmentation — Lack of universal standards for chiplet interfaces.
   
   

4. EDA limitations — Traditional tools are not fully optimized for 3D partitioning.
   
   

5. Supply chain and packaging constraints — Advanced packaging requires high-precision manufacturing

Addressing these challenges requires close collaboration between EDA vendors, foundries (like TSMC, Intel, Samsung), and design houses.

7. How AI and Machine Learning Are Enhancing Chiplet and 3D IC Design

AI is becoming a game-changer in multi-die physical design optimization.
Machine learning algorithms help:

• Predict thermal hotspots and optimize placement.
  
  

• Automate die partitioning based on power and performance metrics.
  
  

• Perform fast PPA (Power, Performance, Area) trade-off analysis.
  
  

• Accelerate timing closure and routing convergence.

With the emergence of AI-driven design tools like Synopsys DSO.ai and Cadence Cerebrus, design teams can drastically shorten development cycles and improve design quality.

8. The Future of Physical Design: A Multi-Dimensional Evolution

The next generation of physical design engineers will operate in a world of heterogeneous integration, AI-assisted automation, and cloud-based EDA environments.
Some key future trends include:

• Standardized chiplet ecosystems for plug-and-play design.
  
  

• Automated 3D design space exploration using AI.
  
  

• Sustainability-focused layouts to reduce power and waste.
  
  

• Open-source 3D design education platforms for academic use.

In essence, physical design is evolving from a 2D layout problem to a multi-dimensional system-level challenge — demanding new tools, skills, and collaboration.

9. Preparing for the New Era of Physical Design

For students and professionals in VLSI, this transformation means learning beyond traditional EDA workflows.

 Key steps to prepare include:

• Understanding 3D integration principles and chiplet architectures.
  
  

• Gaining hands-on experience with EDA tools supporting 3D and chiplet flows.
  
  

• Developing skills in AI, scripting (TCL/Python), and cloud design environments.
  
  

• Exploring open-source projects like Open3DFlow or TinyTapeout to understand packaging-level design.

By embracing these skills early, engineers can position themselves at the forefront of the semiconductor design revolution.

Conclusion

Chiplets and 3D ICs mark a fundamental shift in how chips are designed, assembled, and optimized.
As monolithic scaling reaches its limits, the future of physical design will depend on integration, innovation, and intelligence — connecting multiple dies, layers, and technologies into a single, high-performance system.