Chapter 19: INSPECTION, MEASUREMENT, AND TEST

Chapter 20: GRINDING, STRESS RELIEF, AND DICING

Chapter 21: PACKAGING

The Need for Tests

Why test at all? The simple answer to this question is to increase the confidence of the IC manufacturer that the device-under-test (DUT) will meet its specifications listed in the device data sheet and will perform as designed in its end application. Semiconductor manufacturing processes are not perfect, therefore the good parts need to be sorted from the bad and testing assures customer quality.

Test also plays another, equally important role that of quantifying and identifying the manufacturing defects so they can be reduced and the yield increased. Not only do manufacturers want to ship only good chips, they want to maximize the yield of good chips rather than scrap. By increasing yield, defects are decreased and the probability of a bad part escaping the test is reduced.

Yield is crucial to the profitability of a fab since it determines how much revenue in the form of good chips, can be obtained for the cost of producing a wafer. Furthermore, yield, along with cycle time, sets the capacity of the fab. Thus products, manufacturing processes, and wafer fabrication facilities all go through yield improvement cycles where designs, procedures, and equipment settings are adjusted to decrease the rate of defects. The rate of this yield learning determines the return on the investment in equipping the fab and developing the...