Yttrium oxide/silicon dioxide: a new dielectric structure for VLSI/ULSI circuits

Electrical characteristics of Al/yttrium oxide ( approximately 260 AA)/silicon dioxide ( approximately 40 AA)/Si and Al/yttrium oxide ( approximately 260 AA)/Si structures are described. The Al/Y/sub 2/O/sub 3//SiO/sub 2//Si (MYOS) and Al/Y/sub 2/O/sub 3//Si (MYS) capacitors show very well-behaved I-V characteristics with leakage current density <10/sup -10/ A/cm/sup 2/ at 5 V. High-frequency C-V and quasistatic C-V characteristics show very little hysteresis for bias ramp rate ranging from 10 to 100 mV/s. The average interface charge density (Q/sub f/+Q/sub it/) is approximately 6*10/sup 11//cm/sup 2/ and interface state density D/sub it/ is approximately 10/sup 11/ cm/sup -2/-eV/sup -1/ near the middle of the bandgap of silicon. The accumulation capacitance of this dielectric does not show an appreciable frequency dependence for frequencies varying from 10 kHz to 10 MHz. These electrical characteristics and dielectric constant of approximately 17-20 for yttrium oxide on SiO/sub 2//Si make it a variable dielectric for DRAM storage capacitors and for decoupling capacitors for on-chip and off-chip applications.<
>