Shih-Wei Sun, ex-CEO of Taiwan-based pure-play foundry United Microelectronics (UMC), will join China's state-owned Tsinghua Unigroup to serve as executive VP of worldwide operations, according to industry sources.

Speculation has also circulated in the semiconductor industry that the appointment of Sun could indicate Tsinghua Unigroup's potential ambition in the contract-manufacturing business.

Sun stepped down as CEO of UMC in November 2012 and became the company's vice chairman. In January 2015, Sun applied for retirement and resignation from all positions he held within the Taiwan-based foundry.

Tsinghua Unigroup has hired Rick Tsai, ex-chairman for Chunghwa Telecom (CHT) and ex-CEO of Taiwan Semiconductor Manufacturing (TSMC), to assist in the establishment of a new 12-inch wafer plant in Chengdu and lead the contract manufacturing business within the company.