It is reported that memory manufacturers are considering using flux-free bonding for HBM4 to further reduce the gap between layers

On November 14, according to Korean media ETNews, Samsung Electronics, SK Hynix, and Micron are all interested in using fluxless bonding technology in the next-generation HBM4 memory and are making technical preparations.

SK Hynix has previously announced the 16-layer stacked HBM3E, and overall, HBM memory will officially switch to 16-layer stacking starting with HBM4. Since the bump-free hybrid bonding technology is not yet mature, the traditional bump solution is expected to remain the mainstream bonding technology for HBM4 16Hi.

More DRAM Die layers mean that HBM4 16Hi needs to further compress the gap between layers to ensure that the overall stack height remains within the limit of 775 μm (IT Home Note: 0.775 mm).

In this context, the three major memory manufacturers have all noticed the flux used in the existing HBM bonding process: the flux can clean the oxide layer on the surface of the DRAM Die to ensure that the mechanical and electrical connections will not be affected by the oxide layer during the bonding process; but the flux residue will also expand the gap between the Dies and increase the overall stack height.

Sources said that the three major HBM memory manufacturers have different levels of preparation for flux-free bonding: Micron is the most active in testing the process with partners, SK Hynix is ​​considering introducing it, and Samsung Electronics is also paying close attention to it.