Saturday, May 15, 2010

Biological, inverted microscope layer image comparison

Biological, top metal (220X):
Biological interconnect doesn't image well as all black. Sample for comparison (not same area):
If you are stuck with a biological microscope, set the intensity as high as you can and you should be able to make things out with your eye, but cameras might have more difficulty.
Inverted metallurgical (inverted), top metal (440X):
Inverted metallurgical (inverted), interconnect (440X):
Although all three are from the same chip type, only the two inverted images are from the exact same chip. NOTE: I have done a vertical flip on the inverted images to correct them to what the actual object is like (as in the biological image).
For those wondering where the magnification levels come from, it is a combination of the eyepiece, objective, and camera magnification. For the biological microscope, the image was shot at 10X eyepiece * 10X objective * 2.2X camera = 220X. For the inverted metallurgical microscope, the images were shot at 10X eyepiece * 20X objective * 2.2X camera = 440X. Thus, I (poorly) manually stitched two images together from each to get closer to the size of the biological image.
Alas, despite my best efforts, I still can't see transistors. Today I tried some extended hot baths in HF acid on the chip above and even tried adding some 30% H202 which dramatically increases the action of the HF. I'm letting it sit overnight (or maybe till Wed after finals) and see if it ate through. Maybe these chips are just resistant? I'll have to go back to sanding though to get other sample since I haven't gotten another technique to work yet on epoxied ICs.

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