Crystallized HfLaO embedded tetragonal ZrO2 for dynamic random access memory capacitor dielectrics

Abstract

Cubic-structured HfLaO embedded tetragonal ZrO2 is investigated for application to a dynamic random access memory capacitor dielectric. It is found that hole injection is the determining factor of the leakage current in the ZrO2–HfLaO stack and thus HfLaO should be kept away from the electrode interface due to its smaller valance band offset than that of ZrO2. The insertion of cubic-structured HfLaO into tetragonal ZrO2 with an optimized thickness combination can effectively reduce the equivalent oxide thickness without increasing the leakage current.

Sub-0.5 nm Equivalent Oxide Thickness Scaling for Si-Doped Zr1–xHfxO2 Thin Film without Using Noble Metal Electrode

“…Because the tetragonal structure improves the dielectric properties, the lowest EOT value, under 0.5 nm with low leakage current density (<10 –7 A·cm –2 ) was obtained without using a noble-metal-based electrode. This is the best data for MIM capacitor without a noble metal; the lowest value of EOT ever reported was about 6.1 Å . The data are furthermore comparable with the best results for new higher-k dielectrics, such as TiO 2 and SrTiO 3 , assembled onto noble metal electrodes. , Thus, the Si-doped Zr 1– x Hf x O 2 thin film proposed by this work is a highly promising candidate for DRAM MIM capacitor applications.…”

“…This is the best data for MIM capacitor without a noble metal; the lowest value of EOT ever reported was about 6.1 Å. 25 The data are furthermore comparable with the best results for new higher-k dielectrics, such as TiO 2 and SrTiO 3 , assembled onto noble metal electrodes. 2,3 Thus, the Si-doped Zr 1−x Hf x O 2 thin film proposed by this work is a highly promising candidate for DRAM MIM capacitor applications.…”

Ultrathin ferroic HfO2–ZrO2 superlattice gate stack for advanced transistors

“…The use of short-period superlattices i.e. nanolaminates is common in the high-κ field to enhance permittivity [77][78][79][80][81] ; in particular, rutile-structure TiO 2 is often paired with fluorite-structure HfO 2 and/or ZrO 2 in DRAM capacitors 82 . Recently, fluorite-structure nanolaminates were employed to tune the ferroelectric behavior of HfO 2 -ZrO 2 films [83][84][85] .…”

Abnormally enhanced dielectric constant in ZrO2/Ta2O5 multi-laminate structures by metallic Ta formation

“…High permittivity oxides such as HfO 2 , ZrO 2 , TiO 2 and Ta 2 O 5 have been extensively researched for their application as gate dielectrics and metal-insulator-metal (MIM) capacitor dielectrics in dynamic random access memory devices [1][2][3][4][5]. In particular, the high dielectric constant ($ 40) of tetragonal ZrO 2 crystals and the relatively wide band gap (5.7 eV) of this material have attracted much interest [6,7].…”