A Taiwanese investigation into the possible theft of chip technology at Taiwan Semiconductor Manufacturing Co. is putting a low-profile, lesser-known tech linchpin in Japan under unusual scrutiny.

Three Taiwan Semiconductor Manufacturing Co. employees were taken into custody Tuesday after company officials detected "unauthorized activities" and a leak of its trade secrets related to "core technologies.

The trio are accused of improperly accessing proprietary information on TSMC's 2-nanometer chip development and production.