Instead of fitting all functions onto one large die, multiple dies or wafers are stacked on top of each other and electrically connected using through-silicon vias (TSVs) or hybrid bonding. This drastically shortens signal paths and allows different technologies (logic, memory) to be combined in one package. HBM memory is the best-known example of this technique.
How does a MEMS sensor work?
Micro-electromechanical systems combine tiny mechanical structures — membranes, beams, comb electrodes — with electronic readout on a single chip. Physical quantities like acceleration or pressure minutely deform the mechanical structure, which is measured electrically as a change in capacitance or resistance. They're manufactured using adapted semiconductor processes such as surface or bulk micromachining.
How does wire bonding work?
In wire bonding, a thin gold or aluminum wire connects the chip's contact pads to the package leads. A combination of pressure, ultrasonic energy, and sometimes heat welds the wire to the pad without melting it. It remains the most widely used method for electrical interconnection in chip assembly today.
Why do chips keep getting smaller (Moore's Law explained briefly)?
In 1965, Gordon Moore observed that the number of transistors on a chip roughly doubles every two years — driven by ever-finer lithography and denser devices like FinFETs. Smaller transistors switch faster, use less energy per switching event, and lower the cost per function. In recent years this scaling has been slowing down, which is why advanced packaging and chiplets are gaining importance as a complementary path.
How does flip-chip assembly work?
In flip-chip assembly, the chip is flipped over (hence the name) and connected directly, over its whole face, to the substrate via small solder balls, instead of using wires at the edge as in wire bonding. This allows far more and much shorter electrical connections, along with better electrical and thermal performance. The solder balls are briefly melted (reflow), simultaneously forming a mechanical and electrical bond to the contact pads.
How does a TSV (through-silicon via) work?
A TSV is a vertical, metal-filled hole etched or drilled completely through a thinned silicon die to electrically connect chips stacked above and below it. Before the metal fill, a thin oxide layer insulates the via from the surrounding silicon to prevent short circuits. TSVs form the backbone of 3D chip stacking and enable much shorter signal paths than lateral wiring.
How do chiplets work?
Instead of manufacturing a large chip as a single monolithic die, its functions are split across several smaller dies (chiplets) that are only connected together in the package via fast interconnects. This lets each chiplet be manufactured in whichever process node suits it best, and lets defective dies be discarded individually instead of scrapping the whole chip. Chiplets are typically connected using advanced packaging techniques such as interposers, hybrid bonding, or TSVs.