OpenAI Chief Executive Officer Sam Altman, who has been working to raise billions of dollars from global investors for a chip venture, aims to use the funds to set up a network of factories to manufacture semiconductors, according to several people with knowledge of the plans. Altman has had conversations with several large potential investors in the hopes of raising the vast sums needed for chip fabrication plants, or fabs, as they’re known colloquially, said the people, who requested anonymity because the conversations are private.