Inside Intel: From Silicon to the Worldby Anand Lal Shimpi on February 11, 2002 3:58 AM EST
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If there’s a problem with the wiring in your car you can usually do the re-wiring yourself, because you’re dealing with wires that are inches or even feet in length and are easily accessible (relatively speaking). But what happens if there’s a problem with the wiring inside of a CPU? Instead of dealing with wires that are inches long you’re forced to deal with wires that are 0.03 microns in length. Even if you could somehow get access to the silicon without damaging it you wouldn’t be able to even begin to find the wires you’d need to add or remove in order to fix a problem with the circuit.
There’s another proprietary tool that Intel uses in order to fix these very types of problems – it’s called a Focused Ion Beam (FIB). The FIB tool is another large machine that takes a piece of silicon and instead of detecting problems with it the tool can be used to fix problems.
Our two Intel guides reminded us about the no-camera policy beyond the FIB doors.
Let’s say that using the LVP we mentioned earlier one of the operators discovers that the CPU has an extra NAND gate that must be bypassed. In order to bypass it, the input lines coming into the NAND gate and the output line leaving the gate must be cut, and a new connection must be made between those wires.
In order for the FIB tool to have access to the part of the silicon that it will be operating on the core itself must be shaved down to around 1.7 microns in height. This obviously must be done with the utmost care otherwise the core may develop stress fractures and be completely ruined in the process. Intel has another set of tools that preps the core for use with the FIB tool.
Once in the machine, the FIB can begin cutting wires and inserting new ones through the command of an operator sitting at a workstation. Depending on the complexity of the circuit repair being performed an average operation can take anywhere from a few hours to multiple days; all this just to add or remove a wire that’s hundredths of a micron in length. Keep that in mind the next time you get upset that AMD or Intel delays the release of a new CPU.