Maybe pay your engineering team well and this will happen less often. Based on the reported Taiwanese salaries for TMSC engineers, it's kind of low for the amount of expertise that is required.
The thief is paid well, and greed is the key. Does that mean stealing secrets is justified if the company pays them little? That's not the case, brother. And as a Taiwanese, everyone knows that TSMC is more than just a tech company; it's involved in the lifeblood of Taiwan. Only those who truly love Taiwan would do something like this.