Other semiconductor suppliers use the technique, but Altera is the only PLD producer using this yield-enhancing process. Redundancy is most important when developing new processes and in very large chips. These are the situations where it is much more likely to encounter chip-destroying defects in the manufacturing process. New processes always result in a higher defect density. The density of defects drops as the new process matures and process improvements are made.
Larger chips are obviously more likely to encounter a defect than smaller devices.
Altera tends to remove the redundancy circuits in devices as the process matures. The redundancy circuitry increases the size of the die and becomes an uneconomical technique in high-yield processes. This is the largest part being shipped by the company.