Dat ain't laser markings. I've seen plenty of those and they look completely different. Laser marking is also too expensive. These markings are embedded in the Epoxy using a stamping technique,
Do you have any reference for this?
For this tread I screwed off the barlow lens of my stereo microscope and looked at a bunch of ICs with maximum magnification, and I see a lot of clear indications of laser markings, such as sometimes deeper pits at the end or start of lines. Some very deep ablation by a "more powerful" laser, and the typical rough surface of ablated plastic. I've even seen a few where the individual lines of the laser in the "wider" areas of the texts and logos are visible.
The oldest I saw with laser engravings was an MC6845 with date code 8439.
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I've made some labels for I/O pins microcontrollers and such, and I found that a very easy way to do is is to use a spreadsheet such as in Libre Office , and then set the line height to 2.54mm (Weird number, but it works with most DIP IC's for some inexplicable reason). Then reduce the font size until it fits and print it on any laser printer. Then cover the text with regular clear tape, glue the label onto the IC and cut the edges with a knife running along the IC edge.