Low leakage ZrO2 based capacitors for sub 20 nm dynamic random access memory technology nodes

During dynamic random access memory (DRAM) capacitor scaling, a lot of effort was put searching for new material stacks to overcome the scaling limitations of the current material stack, such as leakage and sufficient capacitance. In this study, very promising results for a SrTiO3 based capacitor with a record low capacitance equivalent thickness value of 0.2 nm at target leakage current are presented. Due to the material properties of SrTiO3 films (high vacancy concentration and low band gap), which are leading to an increased leakage current, a physical thickness of at least 8 nm is required at target leakage specifications. However, this physical thickness would not fit into an 18 nm DRAM structure. Therefore, two different new approaches to develop a new ZrO2 based DRAM capacitor stack by changing the inter-layer material from Al2O3 to SrO and the exchange of the top electrode material from TiN to Pt are presented. A combination of these two approaches leads to a capacitance equivalent thickness value...

[1]  Hongfa Luan,et al.  On Oxygen Deficiency and Fast Transient Charge-Trapping Effects in High-$k$ Dielectrics , 2006, IEEE Electron Device Letters.

[2]  Albena Paskaleva,et al.  Detailed leakage current analysis of metal–insulator–metal capacitors with ZrO2, ZrO2/SiO2/ZrO2, and ZrO2/Al2O3/ZrO2 as dielectric and TiN electrodes , 2013 .

[3]  S.Y. Kim,et al.  Fully Integrated 56 nm DRAM Technology for 1 Gb DRAM , 2007, 2007 IEEE Symposium on VLSI Technology.

[4]  R. Fowler,et al.  The Analysis of Photoelectric Sensitivity Curves for Clean Metals at Various Temperatures , 1931 .

[5]  A. Stesmans,et al.  Photoconductivity of Hf-based binary metal oxide systems , 2008 .

[6]  Kyuho Cho,et al.  Conduction barrier offset engineering for DRAM capacitor scaling , 2016 .

[7]  Paolo Lugli,et al.  Ultimate scaling of TiN/ZrO2/TiN capacitors: Leakage currents and limitations due to electrode roughness , 2011 .

[8]  K. Shiraishi,et al.  Effective-Work-Function Control by Varying the TiN Thickness in Poly-Si/TiN Gate Electrodes for Scaled High- $k$ CMOSFETs , 2009, IEEE Electron Device Letters.

[9]  J. Robertson.  High dielectric constant gate oxides for metal oxide Si transistors , 2006 .

[10]  L. Oberbeck,et al.  SrTiO3 thin film capacitors on silicon substrates with insignificant interfacial passive layers , 2010 .

[11]  C. Hwang,et al.  Evaluating the top electrode material for achieving an equivalent oxide thickness smaller than 0.4 nm from an Al-doped TiO₂ film. , 2014, ACS applied materials & interfaces.

[12]  Nicola A. Spaldin,et al.  Origin of the dielectric dead layer in nanoscale capacitors , 2006, Nature.

[13]  J. Frenkel,et al.  On Pre-Breakdown Phenomena in Insulators and Electronic Semi-Conductors , 1938 .

[14]  A. Stesmans,et al.  Internal photoemission at interfaces of high-κ insulators with semiconductors and metals , 2007 .

[15]  Kyuho Cho,et al.  Ultra-thin ZrO2/SrO/ZrO2 insulating stacks for future dynamic random access memory capacitor applications , 2015 .

[16]  H. Bender,et al.  Impact of bottom electrode and SrxTiyOz film formation on physical and electrical properties of metal-insulator-metal capacitors , 2011 .

[17]  Thomas Mikolajick,et al.  Conduction Mechanisms and Breakdown Characteristics of $\hbox{Al}_{2}\hbox{O}_{3}$-Doped $\hbox{ZrO}_{2}$ High-$k$ Dielectrics for Three-Dimensional Stacked Metal–Insulator–Metal Capacitors , 2014, IEEE Transactions on Device and Materials Reliability.

[18]  C. Hwang,et al.  Improvement in the leakage current characteristic of metal-insulator-metal capacitor by adopting RuO2 film as bottom electrode , 2011 .

[19]  K. A. Nasyrov,et al.  Charge transport in dielectrics via tunneling between traps , 2011 .

[20]  S. Clima,et al.  Low leakage Ru-strontium titanate-Ru metal-insulator-metal capacitors for sub-20 nm technology node in dynamic random access memory , 2014 .