Kee-jeung Lee

Development of New TiN/ZrO2/Al2O3/ZrO2/TiN Capacitors Extendable to 45nm Generation DRAMs Replacing HfO2 Based Dielectrics

New ZrO₂/Al₂O₃/ZrO₂ (ZAZ) dielectric film was theoretically designed and successfully demonstrated to be applicable to 45nm DRAM devices. ZAZ dielectric film is a combined structure from tetragonal ZrO₂ and amorphous Al ₂O₃. Thus prepared ZAZ TFT capacitors showed very small Tox.eq value of 6.3Aring and low leakage current less than 1fA/cell. It was also confirmed that ZAZ TFT capacitor was thermally robust during backend full thermal process by applying it to the final DRAM product in mass production

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

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.

Low Power and Improved Switching Properties of Selector-Less Ta2O5 Based Resistive Random Access Memory Using Ti-Rich TiN Electrode

The effects of TiN top electrode composition (TiN vs Ti-rich TiN) on the resistive switching characteristics of selector-less TiN/TiOx/Ta2O5/TiN resistive random access memory (ReRAM) are investigated. Ti-rich TiN enables TiOx to have a higher concentration of oxygen vacancy and reduce barrier height between top electrode and TiOx. This leads to higher on/off current ratio and lower operation voltage without degradation of non-linearity which is the important factor for selector-less type ReRAM, compared to the stoichiometric TiN resistor stack. Consequently, it is verified that the switching mechanism is hybrid combination of filament formation and redox reaction in switching operation. This work is applicable to both high density and cost-effective ReRAM.

The study of flat-band voltage shift using arsenic ion-implantation with High-k/Metal Inserted Poly Si gate stacks

The origin of flat band voltage shift phenomena using arsenic ion-implant in High-k/Metal Inserted Poly Si (HK/MIPS) gate stacks was investigated. Arsenic ion-implantations were carried out on HfSiO and HfSiON dielectric layers. Precise arsenic profile was obtained through front and backside SIMS analysis. From the electrical and physical analysis, we verified that the flat band voltage was shifted due to an arsenic dipole formation at high-k/metal interface. The negative shift of 480mV was obtained with the optimized arsenic ion implant condition.

Development of highly robust nano-mixed Hf/sub x/Al/sub y/O/sub z/ dielectrics for TiN/Hf/sub x/Al/sub y/O/sub z//TiN capacitor applicable to 65nm generation DRAMs

TIT capacitor with Nano-mixed Hf/sub x/Al/sub y/O/sub z/ dielectric was successfully demonstrated to be applicable to 65nm DRAM devices. Nano-mixed Hf/sub x/Al/sub y/O/sub z/ thin film by ALD(Atomic Layer Deposition) showed an excellent thermal stability even up to 700/spl deg/C without any leakage current degradation. Moreover, Nano-mixed films revealed lower leakage current than laminate due to effective nano-scale mixing of HfO/sub 2/ and Al/sub 2/O/sub 3/TiN/Hf/sub x/Al/sub y/O/sub z//TiN capacitor turned out to be applicable to 65nm DRAM showing low EOT of 11/spl Aring/ and low leakage of 1 fA/cell.