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Basic Terms involved PDF Print E-mail
Written by Aparna Joshi   

Let's see what are the basic terms which are frequently used when engineers talk about test data.

Die: It is an actual product that company is selling as an IC chip.

Reticle: Normally, the whole wafer is not exposed in any photo lithography tool during manufacturing of chips. Only small portion of the wafer is exposed at a time. This area of the wafer that gets exposed is called Reticle.

Scribe lines: These are nothing but grid lines. Also called as sawing lanes. A wafer gets diced along these lines to separate out individual dice.

Wafer: A flat circular starting material for making IC chips. It can be made up of silicon, GaAs. They come in various diameters such as 4", 6", 8" and 12". Newest technology is using 450 mm diameter wafers which converts to 18".

Lot: A set of wafers for one particular IC chip. Production lots normally contain 12 to 25 wafers.

PCM site: An area where PCM test structures are placed are called PCM sites. Some times, the structures are put in the scribe lines. If big test structures are placed in scribe lines, the scribe lines get wider reducing total number of dies. Sometimes engineers place test structures in the die areas instead of scribe lines. Here, scribe lines can be thinner and only few dies are compromised where test structures are placed.

Prober: It is a piece of equipment which actually connects with individual die using spider and sends measurements to a tester attached to it.

Tester: This equipment actually logs the data in a file. There are lot of formats available to log data. Test programs are loaded before starting any testing.

Probe Card: This has fine wires connecting to all the pins on the die on the wafer. It practically extends the pins on the die. It is attached to the prober. It is designed and manufactured as per chip's functional specifications. It can test multiple chips at a time. It saves prober and tester time.

Stepper: It is a part of the prober. It moves the wafer to next set of dies. If the probe card can test 4 dies at a time, the stepper will move to next 4 dies and align all of them with spider for testing.

DUT Board or Load board: This is pretty much same concept as probe card but for final testing of packaged chips. Every packaged part (ready to ship) is attached to the board just like it would be attached in the final circuit at customer side. Then measurements are taken, logged in the file for analysis.

 

 
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