In recent times, suppliers of automatic test equipment (ATE) have announced new, high-speed NAND flash testers, which are equipped with the latest and greatest test handlers. The new gear is supposed to keep up with the explosion in NAND densities and volumes by using conventional parallelism techniques. Advantest, Nextest and Verigy are the main NAND flash-memory ATE suppliers in the market.

But, while ATE vendors are somewhat getting a handle on logic and system-on-a-chip (SoC) test costs, ATE suppliers — the chip makers themselves — are behind the curve in NAND flash.

"The ASPs for NAND have fallen by 50 percent since the beginning of the year," said Tim Moriarty, vice president of sales and marketing for San Jose-based Nextest Inc., a high-flying supplier of ATE. "Unfortunately, the test times are getting longer."

For today's leading-edge devices, it can take a whopping 10-to-30 minutes in order to test each NAND flash-memory part, said Jim Mulady, editor of The Final Test Report, a newsletter that covers the ATE industry.

"In the future, we're looking at 60 minutes each," he warned. "Logic is going the other way. BIST and other technologies are driving the cost of logic test down."

In contrast, NAND flash lacks a viable built-in-self-test (BIST) or scan solution, causing headaches for suppliers of these parts, namely Hynix, Intel-Micron, Toshiba and Samsung.

"In addition to standard protocols, most flash manufacturers use proprietary signaling interfaces and test methods," wrote Gary Fleeman, product manager for ATE giant Advantest America Inc. (Santa Clara, Calif.), in the recent issue of EE Evaluation Engineering. Advantest America is the U.S. sales arm of Japan's Advantest Corp. (Tokyo).

By: DocMemory
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