Understanding Smart Sensors - Nomads.usp

244 Understanding Smart SensorsTable 10.2Cost of Testing for Various Tests (After: [17])Test TechniqueTraditionalTest Wafer level Normal End of lifeGate-oxide evaluation $200 $20,000 $32,000Top-passivation$175 $12,000 $16,000evaluationNew etch process $800 $15,000 $13,000Electromigration testing $350 $7,000 $35,000Hot-electronsusceptibility$750 $9,000 $8,500industry, such as flip-chip and KGD, will also be applied to sensors. Waferlevelreliability will have increased interest for both the sensor manufacturerand the user.Normal test techniques require packaged units and considerably moretime for evaluation. End-of-life techniques require even longer testing to ensurethat a product life (e.g., 20 years) is achievable. For wafer-level testing, additionaltesting at the package level is required because packaging methods have asignificant effect on the total reliability. However, wafer-level reliability testingis one of the ways that semiconductor sensors can continue to achieve lowerproduct cost and continuous improvement.10.6 Testing Smarter SensorsSeveral issues occur for testing sensors that combine other semiconductor technology.Because the ultimate smart sensor (level V in Figure 1.7) is a monolithiccombination of a micromachined structure and an MCU, the challengesthat that combination poses for testing must be addressed. Those challengesinclude, but are not limited to, different types of testing required, unique testequipment, and multipass testing. To allow for a low-cost integrated solution,those issues must be addressed [18].The integration of a physical measurement function onto an already complexmixed-mode analog-digital chip such as an MCU with an integral ADC