Research And Implementation Of Key Techniques For High Coverage And Low Voltage SRAM Testing

With the rapid development of electronic technology,the SRAM is required to have the advantages of low power consumption and high stability during the process of large-scale data information interaction.In the process of strengthening the advantages of SRAM,many new faults have been introduced.After researching algorithms for testing SRAM,it is found that the algorithm has strong limitations,that is,algorithm cannot cover all types of new faults.In order to solve this problem,this paper proposes a low-voltage SRAM adaptive BIST test technology.Based on a large number of researches on various types of faults and effective test elements of SRAM under different PVTs,this paper innovatively proposes the concept of adaptive BIST testing.This technology can diagnose the current SRAM based on the research of SRAM under different PVTs.According to the diagnosis results,the test elements can be flexibly reorganized into the best reconstruction algorithm.The technology includes three modules:SRAM test control module,fault diagnosis module and algorithm generation module.First,the SRAM test control module sets the PVT parameters of the current SRAM.Secondly,the fault diagnosis module accurately diagnoses the current SRAM prone faults based on the research results of various faults in the SRAM under various PVT conditions.Finally,the algorithm generation module maps the diagnosis results to the algorithm set to extract multiple valid test elements to generate a reconstruction algorithm.The article is based on a TSMC 40nm CMOS SRAM,using MBISTArchitect technical process and Fine Sim+VCS tools for simulation verification.The experimental results show that:under the condition of VDD=0.8V,temp=125?,the reconstruction algorithm produced by the low-voltage SRAM adaptive BIST test technology:{?W0,?R0W1R1~3,?R1W0R0~4,?R0W1R1~2,?R1W0R0~2,?R0}.Compared to the traditional March algorithms,the fault coverage has increased by up to 19%,and the test time,area and power have increased by 11%,0.050%and 0.97%respectively.SRAM is prone to dynamic coupling fault when VDD=0.8V and temp=25°C,the test circuit generated by the reconstruction algorithm will automatically switch to another test circuit after the test is completed to continue to test the SRAM,compared with the traditional March algorithm,The fault coverage of the test circuit has increased by 25.7%.