SK Inc., SK Group's holding company, said Friday it has signed a 2.3 trillion-won ($1.6 billion) stock sale deal to hand over its stake in chip materials affiliate SK Siltron to Doosan Group.

Under the decision made at a board meeting held earlier in the day, SK will sell its 70.6 percent stake in the affiliate to Doosan, a South Korean engineering and energy conglomerate, according to a regulatory filing.

The move comes about seven months after SK named Doosan as the preferred bidder in December to acquire SK Siltron following an evaluation on corporate growth potential, job stability and other acquisition conditions.

Established in 1983, SK Siltron is the country's sole dedicated producer of semiconductor wafers, a key material used in chip manufacturing. The company ranks third globally in terms of market share for 12-inch wafers.

The acquisition is expected to help Doosan strengthen its semiconductor materials and equipment portfolio as part of its future growth strategy. The group has also acquired Doosan Tesna Inc., a chip testing company, and Engion, a chip packaging firm.

Doosan aims to increase revenue of SK Siltron to about 3 trillion won by 2031.

SK Group had put SK Siltron up for sale as part of an aggressive restructuring drive since last year aimed at streamlining its business portfolio, with a focus on improving financial soundness and securing long-term growth.