STT-MRAM存储器的故障测试设计

Fault test design of STT-MRAM memories

自旋转移矩的随机存储器(Spin Transfer Torque Magnetic Random Access Memory,STT-MRAM)以其非易失性、读写速度快、数据保持时间长、完全兼容CMOS(Complementary Metal Oxide Semiconductor)工艺等优势在新型存储器中脱颖而出.随着其产业化的投入暴增和应用规模的扩大,STT-MRAM存储器产品的质量和可靠性测试十分必要.当前,最常用的March测试算法在对STT-MRAM的性能进行验证时,存在测试复杂度与故障覆盖率两者不匹配的难题.针对于此,从STT-MRAM的制造缺陷形成和分类出发,将部分针孔故障的表现形式,采用March敏化的方式检测,并基于此类故障类型,提出了一种高故障覆盖率的March CM测试算法,根据此算法设计相应的内建自测试(Build-In Self-Testing,BIST)电路.仿真验证及对STT-MRAM的板级测试显示这一设计达到了兼容高复杂度和高覆盖率的测试要求.

Spin transfer torque magnetic random access memory(STT-MRAM)stands out among the new memory because of its nonvolatile,fast read and write speed,long data retention time,and full compatibility with CMOS(comprehensive metal oxide semiconductor)process.With the rapid increase of its industrialization investment and the expansion of its application scale,it is necessary to test the quality and reliability of STT-MRAM memory products.At present,when the most commonly used March test algorithm verifies the performance of STT-MRAM,there is a problem that the complexity and fault coverage do not match.In view of this,starting from the formation and classification of manufacturing defects in STT-MRAM,this paper adopts the mode of March detection to sensitize some expression of pinhole faults,and based on such fault types,proposes a March CM test algorithm with high fault coverage.According to this algorithm,the corresponding build in self testing(BIST)circuit is designed.Simulation and board level test of STTMRAM show that the design meets the test requirements of high complexity and high coverage.