I understood that each wafer comprises of process control monitor (PCM) data
1. What is it exactly?
2. Why is it important to me as a customer?
3. How much space is it taking on the wafer
The PCM is important in several ways. It is a monitor for the manufacture. It is used to sort between good and pure wafers e.g. 3 out of 5 structures shall pass on the specified parameters. Monitoring the PCM data over time can predict potential issues.
The PCM structures can be placed in scribeline or as dies. It is important that the structures are spread over the wafer i.e. Edge, center, right,left, up and down.
Each fab and each technology has its preferred monitors.
The wafer customer does only see a selection of the PCM data.
If the test structure is in the scribeline it is important that by sawing the wafer this is known information.