The assignee ranking for this field covers 100 companies, with the leading assignee holding 2,720 of the 40,430 records in scope — well ahead of the fifth-place holder at 1,378 and tenth place at 824. The top five assignees combined account for 23.6% of all records, and the top ten for 36.8%, which leaves a substantial long tail of companies with only a handful of filings each. Large integrated device manufacturers, materials specialists and foundries make up most of the concentrated top of the ranking, but no single company controls the majority of the field.

Filing peaked in 2017 at 1,022 records and has trended down since, with the last complete year, 2024, showing 347 filings — a 49% decline from 682 in 2021. Figures for 2025 and 2026 in any chart will look lower still, but that reflects publication lag of roughly 18 months rather than a real-time drop in R&D activity. The safest read is that filing volume has been declining across the 2021-2024 window that can be treated as complete, without extrapolating further from the incomplete recent years.

This Shin-Etsu Handotai application describes producing an SOI wafer by oxidising a bond wafer and/or base wafer to a thickness greater than the target buried-oxide layer, bonding the two through that oxide, and then thinning the bond wafer to reach the final buried-oxide thickness. It is a claim specifically on controlling buried-oxide thickness via pre-bond oxide over-formation and post-bond thinning, not on hydrogen implantation, layer splitting or bonding chemistry generally. Anyone working on buried-oxide thickness control by other means, such as post-bond oxide deposition or different implant-based thinning routes, would need to evaluate their process against this specific sequence rather than assume it blocks the whole SOI wafer category.