本文關(guān)鍵詞：相變存儲器單元脈沖I-V特性測量方法及分析　出處：《華中科技大學(xué)》2013年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 相變存儲器 I-V特性 自熱 能量累積 測量系統(tǒng)

【摘要】：相變存儲器（PCRAM）具有功耗低、速度快、擦寫次數(shù)高、穩(wěn)定性好、與MOS工藝兼容良好、可多值存儲等優(yōu)點，被視為下一代主流存儲器中最具競爭力的新型非易失性半導(dǎo)體存儲器。PCRAM單元的電學(xué)性能一直是半導(dǎo)體信息存儲領(lǐng)域的重要研究內(nèi)容，而電流-電壓（I-V）特性是它最重要的電學(xué)特性之一。通常，PCRAM單元的I-V特性曲線是采用直流掃描的方式測量得到的，直流I-V存在自熱和能量累積效應(yīng)，因為階梯狀電流或電壓激勵會對PCRAM單元持續(xù)地輸入能量，相變材料具有儲熱能特性，那么前面所有歷史臺階產(chǎn)生的熱量會疊加到下一個臺階產(chǎn)生的熱量上。實際上，這種效應(yīng)不僅存在PCRAM單元的直流I-V測量中，還存在脈沖I-V及電阻-電流和電阻-電壓（R-I/R-V）測量中，其導(dǎo)致的直接后果就是破壞它的內(nèi)部特性。實驗證明，經(jīng)過多次I-V測量后的大部分樣品都無法繼續(xù)正常工作，受到不可逆的損壞。所以開展PCRAM單元的自熱和能量累積效應(yīng)的研究是非常有意義的。本論文采用的方法就是研究PCRAM單元的脈沖I-V特性。 由于相變材料以Ge2Sb2Te5（GST）的性能最佳且被最廣泛研究，所以采用存儲介質(zhì)為GST的PCRAM樣品。利用4200-SCS半導(dǎo)體特性分析儀、高精度泰克數(shù)字示波器DPO70064和自主設(shè)計的PCB板搭建一個測量系統(tǒng)，開關(guān)速度快的MOS管、BNC頭、開關(guān)、PCRAM芯片等都集成在PCB板上。通過調(diào)節(jié)PCB板上的開關(guān)，測量系統(tǒng)不僅可以測量PCRAM單元的脈沖I-V特性，，還能測量它的一般電學(xué)性能。采用以上裝置分別測量了相變層厚度為150nm、75nm和25nm的PCRAM單元的直流I-V特性曲線和脈沖I-V特性曲線。對比曲線發(fā)現(xiàn)脈沖I-V測量得到的閾值電壓比直流I-V的大很多，同時也得出脈沖寬度和脈沖周期都是表征PCRAM單元脈沖I-V特性不可或缺的參變量結(jié)論。假設(shè)PCRAM單元活動區(qū)域的溫度上升引起電子活躍性和勢壘的改變，就提出了由自熱效應(yīng)建立的物理模型。
[Abstract]:Phase change memory (PCRAM) has the advantages of low power consumption, high speed, high erasing times, good stability, good compatibility with MOS process, multi-value storage and so on. The electrical performance of a new type of nonvolatile semiconductor memory, PCRAM, which is regarded as the most competitive in the next generation mainstream memory, has been an important research content in the field of semiconductor information storage. The current-voltage I-V) characteristic is one of the most important electrical properties. The I-V characteristic curve of PCRAM cells is usually measured by direct current scanning. DC I-V has the effect of self-heating and energy accumulation, because the step current or voltage excitation will continuously input energy to the PCRAM cell, and the phase change material has the characteristics of thermal energy storage. Then all the heat generated by the historical steps in the front will be superimposed on the heat generated by the next step. In fact, this effect exists not only in the DC I-V measurements of PCRAM cells. There are also pulse I-V and resistance-current and resistance-voltage R-I / R-V measurements, the direct result of which is to destroy its internal characteristics. After several I-V measurements, most of the samples could not continue to work normally. It is very meaningful to study the self-heating and energy accumulation effects of PCRAM elements. The method used in this thesis is to study the pulse I-V characteristics of PCRAM elements. Because the phase change material Ge2Sb2Te5GSTs has the best performance and has been widely studied. Therefore, the storage medium for the GST PCRAM sample, using 4200-SCS semiconductor characteristics analyzer. DPO70064 and PCB board designed by ourselves are used to set up a measurement system with high precision Tak digital oscilloscope. The MOS tube with high switching speed is equipped with BNChead and switch. The PCRAM chip is integrated on the PCB board. By adjusting the switch on the PCB board, the measurement system can not only measure the pulse I-V characteristics of the PCRAM cell. The thickness of phase transition layer is 150 nm. The DC I-V characteristic curves and pulse I-V characteristic curves of 75nm and 25nm PCRAM cells are obtained. The comparison curves show that the threshold voltage obtained by pulse I-V measurement is much larger than that of DC I-V cells. It is also concluded that both pulse width and pulse period are indispensable parameters to characterize the pulse I-V characteristics of PCRAM units. It is assumed that the rise of temperature in the active region of PCRAM cells leads to electron activity and potential. Change of base. A physical model based on the self-heating effect is proposed.
【學(xué)位授予單位】：華中科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2013
【分類號】：TP333

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本文編號：1432055