The main problem is Moore's Law, so everything gets smaller and smaller. The old chips I look at have a single metal layer, which makes it much easier to see wh

The main problem is Moore's Law, so everything gets smaller and smaller. The old chips I look at have a single metal layer, which makes it much easier to see what's going on. And then in the 1990s, feature sizes got smaller than the wavelength of light so my optical microscope can't see the features.