Phil Garrou

Dr. Philip Garrou is a subject matter expert for DARPA and runs his consulting company…

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The expansion of hybrid bonding as a process for high-density packaging was the topic of some presentations presented at the recent SEMI 3D & Systems Summit (held in late January in Dresden).

Xperi and DBI

Xperi announced that its wafer-to-wafer (W2W) hybrid bonding technology “DBI” continues to expand its usage in the image sensor world and his now being introduced by YMTC (Tsinghua Unigroup – China) for NAND layer stacking for SSDs.

FIgure 1: DBI Wafer bonding applications.

DBI Ultra, Xperi’s die to wafer (D2W) hybrid bonding stacking technology stacking that they are positioning for DRAM HBM stacking and 2.5D logic + memory stacking reportedly shows better memory performance through:

  • Improved RLC characteristics
  • Superior thermal performance
  •  Interconnect pitch ~ 1um
  •  Better overall reliability  – Organic materials eliminated
hybrid bonding

Figure 2: DBI Ultra process flow.

Face to Face Hybrid Bonding

GLOBALFOUNDRIES described its efforts in the development of face-to-face (F2F) hybrid wafer bonding as shown below, to allow sub 10um 3D connections. They are attempting to have qualification parts by 1Q2020 (now). They hope to scale to a 1µm pitch.

face to face hybrid bonding

Figure 3: GFs face-to-face hybrid bonding.

Advanced Bonding Technologies

Ruurd Boomsma, CTO of BESI, described advanced bonding technologies for 3D and system in package (SiP). They offered this roadmap for where we are fast approaching in terms of resolution requirements (Figure 4).

Figure 4: Besis advanced bonding roadmap.

In terms of thermal compression bonding (TCB), he contends that issues, such as those shown in Figure 5, are well under control if not fully resolved and that TCB is now a standard HVM process in HBM manufacturing. Next-generation technology will have:

  • accuracy in the 1um range
  • handle die sizes up to 70 mm sq
  • protective atmosphere
  • in situ inspection

Figure 5: Issues with TCB will be resolved in the next-generation of the technology.

He says he feels TCB will reach its limits at 5-10um and the next technology will be “bumpless bonding” (i.e. direct hybrid Cu-Cu bonding). Advanced optics give him hope for future 200nm placement precision. He claims they can currently achieve this at a throughput of 2000 dies/hr. NM accuracy will require particle reduction so tools will have to be built in a cleanroom.

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