Planarization has always been part of the process: https://jeez-semicon.com/blog/Planarization-in-Semiconductor-Manufacturing-Complete-Guide/ https://jeez-semic

Planarization has always been part of the process: https://jeez-semicon.com/blog/Planarization-in-Semiconductor-Manufacturing-Complete-Guide/ https://jeez-semicon.com/blog/Planarization-in-Semiconductor... https://resources.pcb.cadence.com/blog/2023-the-planarization-process-for-semiconductor-manufacturing https://resources.pcb.cadence.com/blog/2023-the-planarizatio... Not dissimilar to lens or mirror making, the process of grinding to a precise flatness. The key step here is bonding it to a glass carrier, presumably because otherwise it gets too thin to support itself. See also the "reduced kerf diamond wire saw": technology critical to cheap solar panels is the ability to saw the boule into thinner and thinner pieces with less waste at each cut, like a big ham slicer.