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Random Testing and Built-In Self-Test
Published in René David, Random Testing of Digital Circuits, 2020
The cost of testing increases rapidly (by a factor of about 10) at each step: wafer testing, package testing, incoming inspection, board testing, system testing, and field testing. Hence, it is important to detect that a circuit is faulty as soon as possible.
Detection and clustering of mixed-type defect patterns in wafer bin maps
Published in IISE Transactions, 2018
Jinho Kim, Youngmin Lee, Heeyoung Kim
The wafer fabrication process consists of multiple sequential processes including oxidation, photolithography, etching, ion implantation, and metallization. After wafer fabrication, a verification test, which is called wafer testing, is performed on each die (or chip) of a wafer using test equipment called a wafer prober to detect any process change and to verify whether all dies meet the product specifications. Wafer testing consists of many test items that measure the performance of the operations of required die functions in order to ensure that only good dies are sent to the next manufacturing stage. In this article, it is assumed that each die is assigned a binary value that depends on the test results for simplicity; for example, a good die is assigned a value of one, whereas a defective die is assigned a value of zero, although in practice a defective die can be further categorized based on its specific defect type (e.g., refresh, disturb failures). The resulting spatial map of a wafer, which shows the assigned binary value of each die, is called a Wafer Bin Map (WBM).
A unified diagnostic framework via symmetrized data aggregation
Published in IISE Transactions, 2023
Yanhong Liu, Haojie Ren, Zhonghua Li
A “barebone” version of wafer testing includes wafer sorting, which tests an individual chip on a wafer using a wafer prober. It also includes wafer final testing, which performs functional testing when production is complete. Rather than testing each wafer before packaging, QA testing uses samples of packaged wafers to test whether the product meets the customers’ specifications. Although “micro-testing” prior to packaging should eliminate visibly defective chips and wafers, high-throughput and high-yield manufacturing processes are incapable of inspecting individual wafer against these specifications, and defer “macro-testing” to QA before delivery to the customers.