Control of metal/oxide electron barriers in CBRAM cells by low work-function liners

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• 作者：F. De Stefano^a ; V.V. Afanas&rsquo ; ev^a ; ^{valeri.afanasiev@fys.kuleuven.be} ; M. Houssa^a ; A. Stesmans^a ; K. Opsomer^b ; ^c ; M. Jurczak^b ; L. Goux^b
• 关键词：Interface barrier ; Internal photoemission ; Work function
• 刊名：Microelectronic Engineering
• 出版年：2013
• 出版时间：September, 2013
• 年：2013
• 卷：109
• 期：Complete
• 页码：156-159
• 全文大小：395 K

文摘

The difference in effective work functions (EWF) between metal electrodes in metal-insulator-metal structures used in resistive switching memory cells determines the value of the static built-in voltage. The latter may affect the retention properties because the corresponding electric field remains present even if no external voltage is applied to the cell. Using the spectroscopy of internal photoemission of electrons, we evaluated the possibility to adjust the EWFs of the back (TiN_y, y ¡Ö 1) and ion-injecting electrodes (Cu or Cu_xTe_1?x) at interfaces with the Al₂O₃ insulator by inserting a thin layer (a liner) of low work function metal (Ta, Ti, Hf). It is found that even a 3-nm thick layer of Ta allows for a reduction of the EWF of copper by ¡Ö1.5 eV. A thicker, ¡Ö6 nm, layer of Ti is required to attain a similarly low EWF while in the case of an Hf liner, scavenging of oxygen from the alumina results in a laterally nonuniform barrier.