One assignee leads clearly with 88 records, well ahead of the fifth-ranked filer at 13. The top five filers together hold 61.6% of all 284 records in scope, and the top ten hold 81.7%, so this is a field where a handful of established semiconductor equipment and device makers control most of the documented claim space. The ranking covers 62 companies in total, with a long tail of firms holding only a few records each.

No — filing activity peaked in 2019 at 17 records, held roughly steady near the 2022 midpoint at 16, and every leading assignee shows zero filings in the most recent tracked year. Some of that drop reflects normal publication lag, since patents typically take around 18 months from filing to publication, so the newest year always looks artificially low. But the flattening trend running from 2022 onward, before the lag window even begins, suggests genuine cooling rather than a purely reporting-driven dip.

US8367303B2, assigned to Micron Technology and granted in 2013, claims a dry develop chemistry combining oxygen, sulfur dioxide and a hydrogen halide such as HBr to remove exposed areas of a carbon-based mask. The addition of HBr to the conventional O2/SO2 chemistry lets an operator tune critical dimension by growing, trimming or sloping sidewalls, while improving sidewall passivation and reducing bowing. Anyone using a similar three-component dry develop chemistry for CD tuning in mask removal should check this claim scope directly rather than assume it only covers a narrow process window.

H01L, the general semiconductor devices class, covers 77.5% of the 284 records, confirming this is primarily a device fabrication field. Beneath that, H10P appears in 26.8% of records and H10B, memory device manufacture, in 19.0%, marking the two largest sub-groupings of claim activity. Because a single record can carry multiple IPC classes, these percentages add up to more than 100% and should not be read as a strict pie chart of the field.

The classes with the lowest record density relative to H01L — H05H (plasma and particle accelerators, 7.0%), B23B (turning and boring, 5.3%) and G03F (photolithography, 5.3%) — are the most likely places to find under-claimed mechanisms rather than crowded prior art. Charging-induced profile correction and aspect-ratio-dependent passivation timing are specific sub-mechanisms named in the search scope that have not generated the same filing density as core mask-selectivity or CD-control claims. A freedom-to-operate search focused on these narrower mechanisms, rather than the broad H01L class, is likely to surface fewer blocking references.