Another critical step is bonding the chiplet within its pit.
Some early research has placed silicon chiplets into pits on an unpatterned silicon wafer, but a good deal of work also has been done in inserting chiplets of multiple species--silicon, GaAs, InP--on the same wafer.
He uses 4" silicon wafers, into which he etches pits for inserting the smaller chiplets. To date he has used both GaAs and silicon chiplets.
TSMC discussed its high-density large package using a six-layer redistribution layer (RDL) interposer to connect four silicon
chiplets and two HBMs.
The technology marshals chiplets into place using software-controlled electrical fields generated by arrays of wires beneath an assembly substrate.
For now, placement is aided by simple positive and negative charges added to chiplets before the wafers are minced.
Another big win Green hopes to score with the modular architecture championed by the CHIPS program is the ability to separate out onto individual chiplets the many IP blocks developed for and aggregated into commercial monolithic chips.
"The program is all about devising a physical library of component chips, or chiplets, that we can assemble in a modular fashion."
Among the specific technologies that could emerge from this newly formed research community are compact replacements for entire circuit boards, ultrawideband radio frequency (RF) systems, which require tight integration of fast data converters with powerful processing functions, and, by combining
chiplets that provide different accelerator and processor functions, fast-learning systems for teasing out interesting and actionable data from much larger volumes of mundane data.
By assembling and integrating dozens of
chiplets, mosaic style, on a so-called interposer, which is like a printed circuit board writ small, all of those microsystems functions could be performed in a much closer huddle and can perform more efficiently than if they were distributed in the usual way among a suite of chips attached to a conventional PCB.
