Taiwan Semiconductor Manufacturing Company (TSMC) will use its 8-inch processing, instead of 12-inch, to produce fingerprint sensors for Apple's next-generation iPhone due to concerns about yield rates for 12-inch wafer-level packaging (WLP), according to industry sources.

　　Apple previously decided to have TSMC produce fingerprint sensors for its next-generation iPhone at the foundry's 12-inch facilities using a 65nm process, the sources noted. However, acknowledging risks associated with 12-inch WLP technologies, Apple has finally chosen TSMC's 8-inch processing which enables mature yield rates for WLP to produce the fingerprint sensors, the sources said.

　　As TSMC shifts back to 8-inch processing to fabricate fingerprint sensors for the next-generation iPhone as done previously, the foundry will continue to subcontract the packaging process to backend houses, the sources indicated. Xintec and China WLCSP are identified as the backend partners.

　　According to Apple's previous decision, which was to have TSMC fabricate the new fingerprint sensors at its 12-inch fabs, TSMC would handle the backend wafer-level chip-scale packaging (WL-CSP) process in-house, the sources pointed out.

　　Yield rates for 8-inch WLP are able to exceed 95%, while those for 12-inch WLP at TSMC's facilities at the Southern Taiwan Science Park (STSP) stay between 70% and 80%, the sources revealed.

　　Fingerprint sensors for Apple's iPhone 5s have been manufactured at TSMC's 8-inch fabs. Produciton of the sensors once suffered unsatisfactory yield rates limiting the availability of the 5s, according to the sources.