Semiconductor History | SK Siltron CSS, Bay City, 29 November 2022 — A Wafer Plant, a President, and a Contested Share Register

At 3:19 in the afternoon on 29 November 2022, a United States president stood on a stage in a Michigan wafer plant that had been ribbon-cut three months earlier. Joe Biden toured SK Siltron CSS with Governor Gretchen Whitmer and Representative Dan Kildee, and spoke about the CHIPS and Science Act. The chief executive, Jianwei Dong, led the tour. The official record of the remarks also lists Chey Tae-won, chairman of SK Group. The plant does not make chips. It makes silicon carbide wafers, the substrate on which power devices are built. Silicon carbide holds high voltages and sheds heat better than plain silicon, which is why it ends up in electric-vehicle inverters and onboard chargers. The company's claim, repeated by the state of Michigan, is that this buys five to ten percent more driving range. The relationship to SK hynix is easy to get wrong. SK Siltron is not a subsidiary of the memory maker; it is a separate SK Group affiliate that supplies wafers to SK hynix and to others, sitting one step upstream in the same conglomerate. The American arm arrived by purchase. SK Siltron's board agreed in September 2019 to buy DuPont's compound semiconductor solutions business for 450 million dollars, and the deal closed on 29 February 2020, bringing with it a plant at Auburn about six kilometres from this pin. Bay City came next, a 300 million dollar second site in Monitor Township, opened on 1 September 2022. In October 2024 the Department of Energy closed a 544 million dollar loan against it. The ownership behind all of this was litigated at home. SK Holdings bought 51 percent of LG Siltron in January 2017 at 18,000 won a share and another 19.6 percent that May, then left the last 29.4 percent to be bought on 30 August by Chey Tae-won personally, at 12,871 won. On 22 December 2021 the Korea Fair Trade Commission fined Chey and SK Inc a combined 1.6 billion won, finding that the group had passed its chairman a business opportunity belonging to the company. It was the first such penalty against the head of a Korean conglomerate. SK denied wrongdoing and said it would consider appealing. The plant is now on its way out of the group. On 31 July 2026 the boards of SK Inc and Doosan approved a share purchase agreement covering the 70.6 percent corporate stake, reported at around 2.3 trillion won. The chairman's 29.4 percent was not part of it. Photo: The White House, public domain, via Wikimedia Commons