Convequity on X
Judging Tower Semiconductor ($TSEM) by how advanced its chip process is misses what its chips are for. Skeptics often set Tower's older 65 nm process against the more advanced processes at TSMC ($TSM). That yardstick suits logic chips, which are judged on transistor density. It does not suit the analog chips Tower makes for optics. 1. In an optical engine, the analog front-end is the circuitry that drives the laser and reads the returning light. It needs speed, linearity and power efficiency, not maximum transistor density. 2. Tower's strength is its silicon-germanium BiCMOS processes. They have long dominated the merchant market for these laser-driver and receiver chips because they deliver high performance without the most advanced CMOS logic. 3. A less noticed strength is hybrid bonding. Co-packaged optics needs an electronic chip bonded reliably onto a photonic one. Tower already runs mature, high-yield hybrid bonding for stacked image sensors in high-end phones, where a signal-processing chip is bonded onto a light-sensing chip. A close technical parallel, already at volume. The limit: if the electronic chip has to take on more complex signal processing, such as clock recovery or adaptive equalization, TSMC's advanced FinFET processes do offer real advantages in power and integration. Different foundries may end up making different parts of the system. So Tower's position in optics rests on silicon-germanium and photonic process expertise, not on advanced logic.
