The emergence of inline screening for high volume manufacturing

The semiconductor content of automobiles is growing rapidly in applications where quality is of paramount importance, and automotive manufacturers have taken the lead in driving a “Zero Defect” mentality into their supply chain. The motivation behind this paper started with engagements with semiconductor suppliers as well as automotive manufacturers, where KLA witnessed many clear examples of killer defects passing through test with the potential to enter the automotive supply chain. The current method to drive towards “Zero Defect” levels of chip quality involve two main approaches: process control and electrical test screening. The industry is poised for a new complementary solution that combines the unique detection of physical defects from the production line with the 100% coverage of electrical test, providing high speed inspection on the most critical reliability layers covering 100% of lots and 100% of wafers to look at each individual die for screening purposes, rather than just controlling the process. By inserting a complementary inline inspection screen, Inline Part Average Testing (I-PAT) can help stop maverick wafers and isolate very defective die. Over the last 2 years KLA has executed proof-of-concept studies for I-PAT using a prototype engineering system. These studies have been conducted at 5 automotive semiconductor integrated device manufacturers (IDMs) and foundries, including logic devices with embedded memory, analog devices, and power semi devices of both silicon and silicon carbide, spanning from 40 to 350nm design rules. The data sets include information on 1.6 million chips to create a meaningful statistical modeling approach. Two case studies are presented that illustrate the effectiveness of inline die screening. Finally, quality and reliability-critical applications beyond automotive are discussed including hyper-scaling data centers and multi-die packaging.