Home
News
Products
Corporate
Contact
 
Monday, January 20, 2025

News
Industry News
Publications
CST News
Help/Support
Software
Tester FAQs
Industry News

DFT - very important for 3D stack testing


Wednesday, January 30, 2013

Nano-electronics research institute imec, has recently announced that it has teamed up with Cadence Design Systems to develop, implement and validate an automated 3D Design-for-Test (DFT) solution to test logic-memory interconnects in DRAM-on-logic stacks. Based on Cadence Encounter technology, the solution was verified on an industrial test chip containing a logic die and JEDEC-compliant Wide-I/O Mobile DRAM.

Memory-on-logic 3D stacks offer the possibility of heterogeneous integration with dense low-power inter-die interconnects. Hence, they are amongst the first 3D products that will come on the market, enabling next-generation high-performance low-power mobile applications.

Recently, JEDEC has released a standard (JESD-229) for stackable Wide-I/O mobile dynamic random access memories (DRAMs) specifying the logic-memory interface. Unlike many previous DRAMs, the standard contains boundary scan features to facilitate interconnect testing. Imec and Cadence now present a design-for-test (DFT) architecture and corresponding automatic test pattern generation (ATPG) approach. It is an extension of their previously announced logic-on-logic 3D DFT architecture and it supports post-bond testing of the interconnects between the logic die and the DRAM stacked on top of it.

The solution implemented by Cadence and imec includes the generation of DRAM test control signals in the logic die and the inclusion of the DRAM boundary scan registers in the serial and parallel test access mechanisms (TAMs) of the 3D test architecture. The automated design for test solution has been validated on an industrial test chip. The design of the test chip is an interposer-based 3D stacked IC which includes a silicon interposer base die, a 94mm2 logic system-on-chip in 40nm technology, and a single Wide-I/O DRAM rank. The validation results show that the silicon area of the additional DFT wrapper is negligible compared to the total logic die size (<0.03%). Moreover, the test pattern generation was very efficient (tens of patterns, generated in only a few seconds) and effective (100% coverage of the targeted faults). All 3D-DFT logic in the logic die was automatically inserted with Cadence Encounter RTL Compiler while the Interconnect test patterns were generated with Encounter Test ATPG.

Part of the work has been performed in the project ESiP, which is co-funded by the ENIAC Joint Undertaking.

 

By: DocMemory
Copyright © 2023 CST, Inc. All Rights Reserved

CST Inc. Memory Tester DDR Tester
Copyright © 1994 - 2023 CST, Inc. All Rights Reserved