Depending on who you talk to, this is a chemical mechanical polisher or a chemical mechanical planarization tool. Used for polishing substances such as silicon dioxide, tantalum and tungsten off of silicon wafers. The method of operation is as follows:
- A cassette of wafers is placed on the load station.
- A small arm comes over and removes one wafer from the load station. The load station elevator then moves down one space.
- The small arm moves back to its original position, and transfers the wafer to the carrier arm. The carrier arm holds the wafer in place with a vacuum.
- The carrier arm takes the wafer over to the first platen. The arm forcibly presses the wafer against the spinning platen, which is coated with slurry. At this stage, oxide or whatever substance is on the wafer is erode
eroded away, as the result of both the chemical reaction caused by contact with the slurry, and the grinding force caused by the friction between the wafer and the platen.
- The wafer may or may not be polished again using a different slurry on the final platen. In our case, we just put DI water on the second platen to rinse and even off the erosion.
- Next, the wafer is carried to the rinse station, a small tank of DI water in which the wafer is spun for a few minutes to make sure all the slurry is rinsed off.
- Finally, the wafer is carried over to the unload station where it is dropped off onto a small platform, and carried by a stream of water to the unload cassette. The unload elevator then moves down one space in anticipation of the next wafer.
- The machine returns to 2, and repeats the process for the next wafer.
The one I deal with regularly is made by IPEC
, model 372M
. It's also about 10 years old and craps out
constantly. I occasionally do stupid things
and wind up breaking parts of it. I had no idea that a stupid little piece consisting primarily of two fiber-optic cable
s could cost $400. Supply and demand
, I guess.