These details are fascinating and non-obvious. Every little tool or part you have to use to work with even 15-year old chip fab processes is under NDA.
It's hard to come up with a good analogy ... it's like you need to write your own serial driver for your new open-source programming language to do any I/O, because you can't call any libraries or OS syscalls because they're all NDA, even on a 15+ year old computer/OS.
It's hard to come up with a good analogy ... it's like you need to write your own serial driver for your new open-source programming language to do any I/O, because you can't call any libraries or OS syscalls because they're all NDA, even on a 15+ year old computer/OS.