As others have pointed out, you will not get contemporary masks and all that without extensive effort. But that might not be useful anyway.
Short answer: you can not just produce everything again after an apocalypse
The manufacturing process is massively complex and if you do not have EVERYTHING needed, including maintenance knowledge for all the required machines that have been falling apart for 20 years, it is borderline impossible to recreate the process and just continue production as if nothing ever happened.
First of all:
What "blueprints" are we talking?
You have to distinguish between what type of "blueprints" we are talking about:
- Hardware description code that is the very basis for any chips functionality (in HDLs, Hardware-description languages, e.g. VHDL, Verilog)
- Masks for production
- A 'script' that details ALL the steps ('turns') of a chips production (including which masks to use for which 'turn')
The first one would allow you to start a new production from scratch as soon as you have access to higher calculatory power AND the synthesis tools to create masks and all that.
Second and third are necessary if one were to continue production, but that require you have access to a functional (and actually clean) clean room with all the machines fully operational. That is a highly unrealistic scenario.
Another thing to consider is the reason for Intels "Copy Exactly!" policy.
Every clean room in the world (for a specific technology node) looks exactly identical. Identical setup, identical machines, identical everything.
The reason is that Intel worked out that recreating a process that worked in one type of lab in another lab can take several years, depending on the amount of differences in machines and materials used.
You can not simply take a 'script' and run it on different machines. It just does not work. You will never get nanometer precision with other machines and identity of chemical processes with even slightly different materials (as in acids that have minimal contamination, etc.).
It is basically impossible and such a recreation would probably take several decades without all the former experts helping you, even if you had all masks and a script.
So the only thing realistic is starting from scratch.
You can NOT just produce smaller technology nodes with the HDL-code for the chips
The reason is that a compilation (code to logical functionality) and especially a synthesis (logical functionality to transistor mapping and wiring on a chip) require massive computational power and high-end software that is (to my knowledge) exclusively temporarily licensed.
So even if you had the power and the software, after the apocalypse all the licenses will have run out and you will not be able to use the tools.
You'd need to get your hands on the codebase for all the tools or get a developer version of the software that works indepentently of any license.
So also recreating 12nm technology is unrealistic even if you had everything
The only option left is to start the entire industry from scratch.
What would be needed to rebuild the semiconductor industry from scratch?
If you had secured all available knowledge about semiconductor chip production, computer engineering, and preferably a few engineers (of many differenty fields), mathematicians, chemists and physicists related to these fields, you will get a lot further than with any blueprints and scripts imagineable.
There are many things to be done:
- Recreating simple processes as used for very early processors
- Develop machines to allow for more complex processes
- Develop software to compile, simulate and synthesize processor designs
- Use the processors and machines you produced to compute more complex designs
- repeat 2., 3. and 4. indefinitely
With all the knowledge secured on what concepts are needed for chip design and production you will probably make very good progress. (depending on how many surviving engineers, etc. you have, and how much people have resources to do non-survival things post-apocalypse.)
The more early processor designs (including documentation) you have secured the quicker the production of more complex ones can start over again.
Recreating the production process with pre-apocalypse technology is very unrealistic, but the more knowledge and expertise you secured the quicker you will be able to recreate chip production capabilities after the apocalypse.