ACM Ultra SFP ap, 2 SFP chambers
CMP station and wet etch/clean chamber configuration
First equipment supply to Chinese OSAT company in the fourth quarter


ACM Research announced on the 30th the 'Ultra SFP ap' for advanced packaging solutions.

The Ultra SFP AP is a single-wafer process tool for surface treatment and wet cleaning applications designed to address issues such as copper overfill in through-silicon vias (TSVs) and wafer warpage in fan-out wafer-level packaging (FO-WLP).

Leveraging ACM's Stress-free Polishing (SFP) technology, the Ultra SFT ap integrates SFP technology with chemical mechanical polishing (CMP) and wet etch chambers into a single system.

The electrochemical reaction mechanism of the Ultra SFP ap electrically removes metal ions from the wafer surface by simultaneously supplying electrolyte and power to the wafer as it rotates on the chuck.

In TSV applications, SFPs are overfilled after TSV filling.The transferred bulk copper is removed to a thickness of 0.2 μm. Next, the wafer is planarized through CMP, and the remaining copper is removed down to the titanium barrier layer. Finally, a wet etching step removes the titanium and exposes the oxide layer.

In FO-WLP applications, the same series of procedures can be applied to eliminate wafer warpage, remove excess copper, and planarize the redistribution layer (RDL).

Because electrolytes and wet etching chemicals are recycled and reused in real time through a built-in electrolyte recycling system, the Ultra SFP AP significantly reduces overall consumable usage. The ability to recover removed metals allows them to be reused for other purposes.

The Ultra SFP AP 335 consists of two SFP chambers, one CMP station, and two wet etch/clean chambers. Process chemicals include electrolyte, copper slurry, copper etchant, and titanium etchant. All three processes achieve a removal rate of 0.5 µm/min, within-wafer non-uniformity of less than 3%, and wafer-to-wafer non-uniformity of less than 1.5%.

Meanwhile, ACM announced that it delivered its first Ultra SFP AP device to a Chinese WLP company in the fourth quarter of 2019. The company is currently verifying the device in its R&D line, and the first performance data is expected mid-year.