Backend process measurement is important for controlling the final quality of the IC package. Problems in IC packaging can cause connection issues when the device is soldered, detaching of wire bonds or bump on chip contacts and increased stress to be placed on the circuits of the IC. For these reasons it is important to control not just the geometry of the die, but also the flatness of the die seating area, the step height between the attachment points on the die and the package and the roughness of the wire bond attachment areas.

Metrology

Flatness
Matching the flatness of the die with that of the die seating area is important to reduce stress placed on the IC during the packaging process and throughout the operation of the device. Controlling the flatness of the overall package is also necessary to ensure correct placement of the IC and good electrical contact being made when soldered.

Roughness
The surface finish of the die seating area needs to be controlled to ensure good adhesion when the die is attached. Also the roughness of the wire bond attachment areas is important for good electrical conductivity and wire attachment security.

Step Height
There are many application for step height on the IC package. From the measurement of balls, bumps and leads to the package geometry itself including depth of the die seating area.