<tex>$hbox HfO_2$</tex>MIS Capacitor with Copper Gate Electrode

Abstract

Metal-insulator-semiconductor capacitors were fabricated using atomic vapor deposition HfO 2 dielectric with sputtered copper (Cu) and aluminum (Al) gate electrodes. The counterparts with SiO 2 dielectric were also fabricated for comparison. Bias-temperature stress and charge-to-breakdown ( BD ) test were conducted to examine the stability and reliability of these capacitors. In contrast with the high Cu drift rate in an SiO 2 dielectric, Cu in contact with HfO 2 seems to be very stable. The HfO 2 capacitors with a Cu-gate also depict higher capacitance without showing any reliability degradation, compared to the Al-gate counterparts. These results indicate that HfO 2 with its considerably high density of 9.68 g/cm 3 is acting as a good barrier to Cu diffusion, and it thus appears feasible to integrate Cu metal with the post-gate-dielectric ultralarge-scale integration manufacturing processes.

Performance Improvement of Conductive Bridging Random Access Memory by Electrode Alloying

“…After the formation of Cu n+ ions, they are drifted into the oxide layer under the electric field, as shown in Figure f. Due to the low ion mobility in hafnium oxides, Cu n+ ions are reduced before they are drifted to the counter electrode, indicating that the growth mode of Cu conductive filaments in the HfO x switching layer is from the active electrode to the counter electrode. ,− When the Cu conductive filament connects the top and bottom electrodes, the device is switched to the low resistance state (LRS), which is consistent with the TEM characterization results in Figure . When a reverse bias is applied to the top active electrode, the Cu atoms in the narrowest region of the conductive filament near the bottom electrode are oxidized to Cu n+ ions and are drifted along the electric field direction.…”

Investigation of top gate electrode options for high‐k gate dielectric MOS capacitors

“…Silicon dioxide gate dielectric films thinner than 3 nm, required for gate lengths smaller than 0.1 µm, suffer from high direct tunneling leakage current, worsened polysilicon gate depletion and boron penetration [1,2]. High-k gate dielectrics (k > 3.9), such as ZrO 2 , Al 2 O 3 and HfO 2 , offer a very good alternative, since a thicker gate dielectric can be used for similar electrical characteristics [3][4][5]. However, despite some efforts to fabricate devices with high-k dielectrics and polysilicon gates [6,7], most high-k gate dielectrics are not compatible with the polysilicon gate electrode.…”

“…However, despite some efforts to fabricate devices with high-k dielectrics and polysilicon gates [6,7], most high-k gate dielectrics are not compatible with the polysilicon gate electrode. So, several metal electrodes have been studied as replacements for gate materials [5,[8][9][10]. Considering the many requirements the gate electrode material should meet, namely low electrical resistivity, high thermal stability, low reactivity, adequate work function for p-channel and n-channel devices, and easiness to deposit and process, refractory metals such as Ta, W, and Mo seem very promising.…”