Delete comment from: Ken Shirriff's blog
Fun little tidbit: that 5" wafer was exposed with a GCA stepper, probably an 8500 given the date and wafer size. You can tell from the distinctive alignment marks (the + and x superimposed crosses in the upper left of the die). A lot of these are still kicking in university cleanrooms...
It's always fun to see die with the streets intact, as you can tell a lot about the process and what tools were used.
I don't know what was used to expose the 4" wafer, but it might be a contact aligner of some type.
Jan 25, 2021, 11:36:32 PM
Posted to Examining a technology sample kit: IBM components from 1948 to 1986