Tektronix manufactured their own ICs with a number of different processes. They built the Microelectronics Building 59 in 1980. In 1985 they spun the GaAs IC group out as Triquint. In 1994 Tektronix sold their IC group and building 59 to Maxim.
This November 15, 1974 TekWeek features an article on IC manufacturing. Click on the image to view the PDF.