Good scan = good quality level? Well, it depends

Summary form only given. Quality can be defined as "a degree of excellence". In practice, we use testing as a measure of the outgoing quality of devices. The problem is that there is not a one-to-one correlation between test and quality. Just because a unit is tested doesn't guarantee that it is defect-free. Similarly, "guaranteed-by-design" functionality, usually isn't. So, what does it mean when we talk about quality level? In essence, we are trying to increase our confidence that devices shipped to customers will work as advertised in their application. For existing products, this is relatively straightforward because of the existing history of how the device performed in the field. For new designs, the difficulty lies in trying to predict this confidence level based on simulations and engineering data. Sometimes we can extrapolate from previous generations of a design or other devices which are being manufactured on the same process technology node. But, these alone are not enough to provide a perfect forecast of how the device will succeed. As a result, the usual method of attack is to apply whatever test techniques are available and can be practically implemented for first silicon.