First of all, there is an excellent -- and, as far as I can see, accurate -- summary of the process technologies (lithography) used with each of the Intel processor microarchitectures in Wikipedia (see: https://en.wikipedia.org/wiki/List_of_Intel_CPU_microarchitectures).
If you want a more official answer, you should be looking on Intel's ark.intel.com web site. The lithography of each processor is included in its Essential information display.
To paraphrase, Intel introduced the 14nm lithography with the Broadwell processors in 2014. 10nm was first introduced in the Cannon Lake processors (the Core i3-8121U, used in the NUC8i3CYS NUCs) in 2018, but volume shipments will not occur until the Ice Lake processors this year (2019).
Hope this helps,