Voltus Voice: Multi-Chiplet Marvels – Exploring Chip-Centric Thermal Analysis

Voltus IC Power Integrity Solution is a power integrity and analysis signoff solution that is integrated with Cadence's full suite of design implementation and signoff tools to deliver the industry’s fastest design closure flow. The aim of this blog series is to broadcast the voices of different experts on how design engineers can effectively use the diverse Voltus technologies to achieve high-performance, accuracy, and capacity for next-gen chip designs.

Welcome to part 3 of our exploration into the world of 3D-IC technology. In the previous posts, we navigated from early rail analysis and IR-aware implementation for individual dies and 3D-ICs to power integrity signoff of 3D-IC designs. Now, in this installment, we shift our focus to a critical aspect that plays a pivotal role in the success of 3D-ICs - Chip-centric Thermal Analysis.

The relationship between power consumption and thermal dynamics for chips is intricate. As power is consumed during the operation of a chip, it results in the generation of heat. This heat may dissipate from the device, metal routing, or the die itself, leading to increased temperatures on the chip. The dissipation process perpetually expends redundant energy, thereby compromising on the overall chip efficiency. Within the materials encapsulated within a chip, heat can be transferred via conduction, convection, or radiation. As long as heat is produced, it dissipates throughout the system, establishing a feedback loop. The apprehension towards heat issues within a chip is rooted in the degradation of chip performance as temperature rises. The escalation of temperature leads to a substantial increase in leakage current, causing numerous transistors to enter a runaway situation. Circuits are meticulously designed under reasonable constraints; however, when heat-related issues arise, one can envision a scenario where most of the power is generated through the charging and discharging of parasitic capacitances during transitions.

Addressing the mitigation of heat and its associated challenges within a chip or system poses a formidable task in the semiconductor industry.

From the Bottom: Voltus Power Analysis

In the context of 3D-IC and modern packaging, smaller chips have high interconnect density and clock frequency. As clock frequency increases, the heat generated due to capacitance-related power consumption becomes an integral factor to be addressed for effective thermal management in 3D-ICs. This scenario accentuates the complex trade-off between performance and thermal considerations. The operation of transistors and devices generates heat, prompting Voltus power analysis to elucidate the nature and quantity of heat produced—whether it be due to internal power, leakage power, or transition power. Concurrently, Voltus conducts an analysis of power and extracts information on the metal and via density within a die.

Upon the calculation of power and metal density, a succinct representation can be generated by constructing a power and metal density map with tiles, such as a 100x100 grid, facilitating the storage of results in the form of the Voltus Thermal Model (VTM) file.

To the Top: Voltus-Celsius Chip-Centric Thermal Analysis

As the story extends from the die to the system, the VTM file, containing the power and metal density data, assumes significance in thermal analysis. Conduction and dissipation represent the physics analysis in this context, integral to system analysis, creating a feedback loop with power production within the die.

In the Voltus-Celsius chip-centric thermal analysis, the VTM file transitions to the Celsius engine.

Celsius performs thermal analysis using the die’s six surface temperature boundary conditions and the VTM file. Thermal analysis, incorporating power maps, metal density maps, and thermal conductivity information for each material, is completed through thermal conduction and dissipation. This process results in the derivation of a temperature map for the die.

The System thermal engineers can employ strategies such as heatsinks, forced liquid cooling, or fans to mitigate heat-related issues. On-chip temperature sensors further enhance efficiency by enabling precise control of each core's performance in response to actual temperature. Advanced packaging, exemplified by 3D-IC, plays a pivotal role, enabling thermal dissipation not only along two dimensions but also vertically, thereby substantially enhancing system thermal capabilities.

To Sum Up

Managing and mitigating heat is crucial in preserving the longevity and reliability of electronic products. The significance of thermal analysis in 3D-IC designs cannot be overstated, as it serves as a linchpin in ensuring both the performance and durability of products. By anticipating the severity of thermal issues in the upcoming technology nodes, the chip-centric thermal analysis is a giant leap towards on-die and full-system PPA-driven solution.

Related Resources

For more information on Cadence digital design and signoff products and services, visit www.cadence.com/go/voltushs.

About Voltus Voice

“Voltus Voice” showcases our product capabilities and features and how they empower engineers to meet time-to-market goals for the complex, advanced-node SoCs that are designed for next-gen smart devices. In this monthly blog series, we also share important news, developments, and updates from the Voltus space.