[Semiconductor] HBM Packaging in 2025: From MR-MUF and TC-NCF to Hybrid Bonding as the Next Standard

 

HBM Packaging 

[Posting: 2025.08.19]

In 2025, the competition in HBM packaging centers on the evolution of stacking methods. SK hynix, with its MR-MUF process, has stably mass-produced 12-Hi stacks, securing advantages in thermal paths and yield, and is preparing for 16-Hi expansion. Samsung Electronics emphasizes mechanical compatibility by implementing 12-Hi at the same height as 8-Hi through precise TC-NCF stacking, while differentiating with its I-Cube/H-Cube platforms for logic integration. Micron challenges the HBM3E market with a focus on power efficiency, strengthening its position through adoption in NVIDIA’s H200. For next-generation HBM4, featuring a 2,048-bit interface and 2 TB/s bandwidth, hybrid bonding is emerging as an essential technology. While MR-MUF and TC-NCF coexist in the current generation, hybrid bonding is expected to become the standard going forward.

Complete Analysis of HBM Packaging Stacking Methods: MR-MUF vs. TC-NCF vs. Hybrid Bonding and Competitor Pros & Cons

Executive Summary

High Bandwidth Memory (HBM) uses TSV (Through-Silicon Via) to vertically stack DRAM dies into a “cube,” which is then integrated with GPU/ASICs via 2.5D interposers or advanced packaging. The stacking method is a critical factor that determines yield, throughput, thermal performance, and scalability.

  • MR-MUF (Mass Reflow + Molded Underfill): Strong in productivity and thermal path management, ideal for 12-Hi/16-Hi stacking.

  • TC-NCF (Thermal Compression + Non-Conductive Film): Strong in height control and precision alignment, widely used by Samsung.

  • Hybrid Bonding (Cu-to-Cu, bump-less): Next-gen solution for HBM4, enabling higher density, better electrical performance, and reduced stack thickness.

  • Integration platforms differ: TSMC CoWoS (S/L/R) vs. Samsung I-Cube/H-Cube.

1) Fundamentals of HBM Stacking

  1. TSV formation → holes etched into DRAM wafers and filled with copper.

  2. Microbump bonding → die-to-die electrical connections.

  3. Underfill application → mechanical reinforcement and stress relief.

  4. Stack capping and thinning → final height and planarization.

The bonding + underfill approach is what differentiates MR-MUF, TC-NCF, and Hybrid Bonding.

2) Technical Comparison of Stacking Methods

TC-NCF (Thermal Compression + Non-Conductive Film)

  • Process: Sequential stacking, with an insulating film placed between dies, compressed with heat and pressure.

  • Advantages:

    • Excellent height control and coplanarity, enabling Samsung’s 12-Hi HBM3E with the same height as 8-Hi modules.

    • Reliable gap filling with reduced void formation.

  • Disadvantages:

    • Sequential bonding = lower throughput.

    • Limited number of thermal dummy bumps → challenges for heat dissipation in high-stack, high-power designs.

MR-MUF (Mass Reflow + Molded Underfill)

  • Process: Dies are stacked and then encapsulated with molded underfill in one batch reflow process.

  • Advantages:

    • Batch process = higher throughput and productivity.

    • Allows more thermal dummy bumps, improving thermal paths for 12-Hi and 16-Hi stacks.

    • Stronger mechanical support with conductive fillers for thermal conduction.

  • Disadvantages:

    • Mold stress and warpage management is more complex.

    • Requires fine-tuned material engineering.

Hybrid Bonding (Cu-to-Cu, bump-less)

  • Process: Direct Cu-Cu bonding at die surfaces, without microbumps or underfill.

  • Advantages:

    • Pitch scaling: much tighter I/O density.

    • Stack height reduction (~15%), lowering thermal resistance.

    • Improved electrical performance (low RC, lower power).

  • Relevance to HBM4:

    • Required to support 2,048-bit bus width and ~2 TB/s per stack.

    • Industry adoption expected from 2025–2026 onward.

3) Integration Platforms: Logic + HBM

  • TSMC CoWoS

    • CoWoS-S: Large silicon interposer (~2,700 mm²).

    • CoWoS-L/R: Organic/RDL-based interposers for even larger packages with stress mitigation.

    • Used in NVIDIA’s latest AI GPUs (Blackwell).

  • Samsung I-Cube / H-Cube

    • I-CubeS/E: Silicon vs. embedded bridge solutions.

    • H-Cube: Hybrid substrate mixing fine-pitch + HDI, designed for up to 8–12 HBM integration.

4) Competitor Packaging Strategies

SK hynix

  • Core Technology: Advanced MR-MUF.

  • Strengths:

    • Leading in throughput, yield, and thermal path design.

    • Pioneered 12-Hi and preparing for 16-Hi.

  • Weaknesses:

    • Needs smooth transition to Hybrid Bonding for HBM4+.

Samsung Electronics

  • Core Technology: TC-NCF with precise height control.

  • Strengths:

    • Achieved 12-Hi HBM3E at same height as 8-Hi.

    • Strong platform integration via I-Cube/H-Cube.

  • Weaknesses:

    • Thermal path limitations under extreme stacking.

    • Actively evaluating MR-MUF and Hybrid Bonding to remain competitive.

Micron Technology

  • Core Technology: TC-NCF with focus on power efficiency (claimed ~30% better than peers).

  • Strengths:

    • Strong efficiency appeal; adopted in NVIDIA H200 accelerators.

  • Weaknesses:

    • Needs to enhance high-stack reliability and transition roadmap toward Hybrid Bonding.

5) Comparative Table

FactorTC-NCFMR-MUFHybrid Bonding
ProcessSequentialBatch reflowDirect Cu-Cu
ThroughputLowHighMedium
Thermal PathLimited dummy bumpsMore dummy bumpsLowest thermal resistance
Stack HeightExcellent controlChallengingReduced (~15%)
Scalability (12-Hi/16-Hi)ModerateStrongBest
MaturityHighHigh (tuning needed)Emerging

6) Key Insights

  1. Current Generation (HBM3E) → MR-MUF leads in yield, throughput, and thermal performance.

  2. Samsung’s TC-NCF → valuable for precision and height constraints.

  3. Micron → positions itself around efficiency rather than stacking height.

  4. Next Generation (HBM4) → Hybrid Bonding becomes mandatory for 2,048-bit I/O and thermal management.

  5. Integration Platform Choice (CoWoS vs. I-Cube/H-Cube) is equally critical for system reliability and scalability.

Summary

HBM packaging technologies—TC-NCF, MR-MUF, and Hybrid Bonding—are shaping the next generation of memory integration.

  • MR-MUF dominates current 12-Hi/16-Hi HBM3E with superior throughput, yield, and thermal performance.

  • TC-NCF remains valuable for height control and precision stacking, as proven by Samsung’s 12-Hi designs.

  • Hybrid Bonding (Cu-to-Cu) is the future for HBM4, enabling 2,048-bit bandwidth and ~2 TB/s per stack.

  • At the system level, TSMC CoWoS-S/L/R and Samsung I-Cube/H-Cube provide different approaches to large-scale HBM + logic integration.

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