Phase change memory alloys: GST cell array characterization using picosecond ultrasonics

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• 作者：W. Ren^a ; M. Zhong^a ; J. Dai^b ; ^{Johnny.Dai@Rudolphtech.com} ; P. Mukundhan^b ; M. Zhang^c
• 关键词：Phase change memory ; Picosecond ultrasonics ; GST ; GST cell array ; Thickness
• 刊名：Microelectronic Engineering
• 出版年：2011
• 出版时间：May 2011
• 年：2011
• 卷：88
• 期：5
• 页码：822-826
• 全文大小：979 K

文摘

Phase change random access memory alloys (PRAM or PCM) are a class of non-volatile memory that is thought as viable alternatives to flash memory technology or to supplement other memory technologies depending on the end applications and its key performance requirements. Ge₂Sb₂Te₅ alloy (GST) is the most widely used chalcogenide material for PCM application, and has many unique properties, including strong temperature-dependent film properties, low thermal conductivity, and high electrical resistivity. Picosecond ultrasonics was used to make non-contact, non-destructive measurements of GST films on blanket wafers and directly on product wafers. On-product wafer measurements were made on various via array (0.5 μm and 1 μm between cell edges with CD size from 250 to 800 nm). Measurements have shown excellent correlation to cross-section SEM and were consistent with CMP polish times for both blanket and pattern wafer measurement. Excellent repeatability based on extensive measurements demonstrates the capability and reliability of picosecond ultrasonic technology. Picosecond ultrasonic measurements also provide rapid characterization across the whole wafer at production-worthy throughputs.