Liang Mong-song was sued by TSMC in 2011 claiming that the chip designer had given trade secrets to Samsung and broken his non-compete agreement. As evidence, the company submitted a lengthy report it commissioned from outside experts which compared various features of TSMC products against the manufacturing characteristics of their Samsung counterparts.

TSMC argued that its products began to increasingly resemble TSMC’s own hardware. According to TSMC’s engineers, the two foundries’ now have nearly identical 14/16nm process nodes.

Liang left TSMC to teach in South Korea, but the foundry later discovered that the university he “taught” at was the Samsung Institute of Technology and his students were all veteran Samsung engineers. Liang was banned for working for Samsung until December 31, 2014.

While that is all very well it does not explain why TSMC fell behind Samsung in developing its processes. CommonWealth said that Liang tapped his knowledge of TSMC’s cutting-edge implementations at the worst worst possible time.

Liang left TSMC after he was passed over for promotion and felt his work was under-appreciated by his former employer.