Is it possible to check signal at a node inside chip after fibrication?

Hi Analog Design

Yes, it is possible to do it. You can do it using either of the following way:

a. Add a test multiplexer in your chip. The inputs to the multiplexer will be connected to different points in the design. Control/output signals for the multiplexer will go through the pins of the chip. The multiplexer should have high input impedance so that there is no significant loading on the various points to which it is connected to.

b. Remove the top of the chip and add a probe. View output in oscilloscope.

Hope that I am not misunderstanding your question. : )

Best regards
Quek

I think what he means is to take measurements at points other than those given I/O pads in a fab'd chip. Short answer I am confident is no, although there may be some cost ineffective way to do this that I'm not aware of. This is especially true if you are packaging and not probing. I did wafer probing in my prototype fabs and dropping a needle onto a trace will destroy it and possibly devices or traces around it depending on spacing. Probe pads which were 100um x 100um eventually were damaged after several attempts and a new die had to be used, so trying to probe a wire which is maybe tens or hundreds of nanometers in width is pointless, the tip will just tear through it.