Cryogenic etching cools the substrate, typically well below room temperature, during plasma etching so that sidewall passivation forms more effectively and the etch profile stays vertical over deep, high-aspect-ratio features. It is used for through-silicon vias, MEMS trenches and, notably in this dataset, inkjet printhead nozzle structures. The technique is one of two dominant approaches for deep reactive-ion etching, the other being the room-temperature Bosch process with its alternating etch and passivation cycles.

The Bosch process alternates etch and passivation steps at room temperature, producing the characteristic scalloped sidewalls that this dataset’s search terms specifically target. Cryogenic etching instead relies on continuous low-temperature operation to form a thin passivation layer in situ, generally producing smoother sidewalls with less scalloping but requiring tighter substrate-temperature control. Patent filings in this space often address exactly that trade-off — profile smoothness versus process-window sensitivity.

The ranked list covers 100 companies, with the leading assignee holding 453 of the 3,280 records in scope and the top five together holding 36.3% of all records. The field includes semiconductor equipment makers, device manufacturers and, historically, inkjet printhead companies whose deep-etch fabrication overlaps with semiconductor process chemistry. Several of the largest historical filers show no filings in the most recent tracked year, so current leadership may differ from cumulative leadership.