Jung-min Park

Impacts of Zr Composition in

The effects of Zr composition on the crystallization behaviors and reliability characteristics of atomic-layer-deposited Hf_1-x Zr_xO_y (0 ≤ x ≤ 1) gate-dielectric films are examined. n-Channel metal-oxide-semiconductor field-effect transistor (nMOSFET) devices with ZrO₂ gate dielectrics showed a much smaller V_th shift under the positive bias stress compared with the same device with HfO₂ gate dielectrics. The impact of Zr composition on the crystallization temperature, crystalline phases, and surface morphology of Hf_1-x Zr_xO_y films is studied. As the Zr composition in the Hf_1-x Zr_xO_y films increased, the reduction of crystallization temperature and the transformation from a monoclinic to a tetragonal phase were observed. The grain size of the crystallized ZrO₂ film is much smaller than that of crystallized HfO₂. The Hatband voltage (V_fb) shift under positive gate-bias stress in p-channel MOS capacitor (pMOSCAP) devices show a similar trend to the Vth shift in nMOSFET devices. In addition, the annealed ZrO₂ films show a large reduction in the V_fb, shift under the positive bias stress compared with as-deposited ZrO₂ in pMOSCAP devices. The improved bias-temperature-instability characteristics of ZrO₂ compared with that of HfO₂ is related to the smaller grain size of crystallized ZrO₂.

\hbox{Hf}_{1-x} \hbox{Zr}_{x}\hbox{O}_{y}

This study examined the positive bias temperature instability (PBTI) of n-type metal-oxide-semiconductor field effect transistor (nMOSFET) characteristics and the negative bias temperature instability (NBTI) of p-type metal-oxide-semiconductor field effect transistor (pMOSFET) characteristics of HfO 2 gate dielectrics with a metal gate. The interface trap charge (one) and bulk oxide trap charge (ΔN ot ) densities were separately estimated to determine the defects responsible for the threshold voltage (V th ) shift during the BTI stress. The contribution of ΔN it to the V th shift for nMOSFET PBTI and pMOSFET NBTI was ~5 and ~30%, respectively. In addition, the estimated activation energy (E a ) of ΔN it and ΔN ot was 0.10 and 0.03 eV, respectively, for nMOSFET PBTI, and 0.11 and 0.17 eV, respectively, for pMOSFET NBTI. It was confirmed that the main degradation mechanism of nMOSFET PBTI is related to the generation of oxide trap charges. However, the degradation under pMOSFET NBTI stress is due to the generation of both interface states and oxide trap charges. By measuring the stress and recovery characteristics under various bias conditions, it was also found that the electron trapping/detrapping characteristics are dominant in the nMOSFET, whereas the generation of both hole trapping/detrapping and interface states competitively occurs in the pMOSFET.

Gate Dielectrics on Their Crystallization Behavior and Bias-Temperature-Instability Characteristics

HfO<inf>2</inf>, HfZr<inf>x</inf>O<inf>y</inf> and ZrO<inf>2</inf> gate dielectrics are systematically compared in terms of the nMOS PBTI and pMOS NBTI. Compared to HfO<inf>2</inf>, ZrO<inf>2</inf> exhibits higher capacitance and superior nMOS mobility characteristics. In addition, as the ZrO<inf>2</inf> content increases, V<inf>th</inf> shift under the nMOS PBTI stress is dramatically reduced. This is mainly contributed to the lower density of pre-existing bulk traps related to the oxygen vacancies.

Bias Temperature Instability Characteristics of n- and p-Type Field Effect Transistors Using HfO2 Gate Dielectrics and Metal Gate

We have successfully integrated a mass production worthy MIM capacitor on gate polysilicon (MIM-COG) structure using HfO₂/HfO_xC_yN_z/HfO₂(HNH) dielectric for the analog/RF/mixed signal application. The insertion of HfO_xC_yN_z into HfO₂ films can successfully suppress the crystallization. As a result, HNH film shows superior breakdown and VCC-a characteristics compared to HfO₂-AI₂O₃ multilayer stack. In addition, we suggest novel MIM-COG structure, which can solve metal routing issues in integration of conventional MIM capacitors. Also, by utilizing the MIM COG structure, the total number of mask can be reduced. Finally, MIM-COG structure with HNH dielectric shows high capacitance density (8.3fF/um²) and low VCC-a (700 ppm/V²). Moreover, excellent operation voltage for 10 year lifetime of MIM-COG structure with HNH (4.6 V) is achieved.

Systematic study on bias temperature instability of various high-k gate dielectrics ; HfO 2 , HfZr x O y and ZrO 2

The dielectric properties and bias temperature instability characteristics of in situ nitrogen incorporated ZrO x N y gate dielectrics were compared with those of ZrO 2 , HfO 2 , and HfO x N y . ZrO x N y showed a much smaller capacitance equivalent oxide thickness (1.43 nm) than ZrO 2 (2.13 nm) and exhibited a turn-around effect under a positive gate stress bias in n-type metal oxide semiconductor field-effect transistor, which is consistent with HfO x N y . However, compared to HfO x N y , ZrO x N y showed a significantly lower initial V th shift under a positive gate stress bias due to the lower number of shallow bulk traps related to oxygen vacancies.

Mass Production Worthy MIM Capacitor On Gate polysilicon(MIM-COG) Structure using HfO 2 /HfO x C y N z /HfO 2 Dielectric for Analog/RF/Mixed Signal Application

This letter examines the turn-around effect of a threshold voltage (Vth) shift of an n-type transistor with atomic-layer-deposited HfOxNy gate dielectrics under a positive gate bias. Vth shifted to the positive voltage direction during the first second due to electron trapping at the preexisting trap sites in the gate dielectrics, which then shifted to the negative voltage direction. This turn-around effect was attributed to hole trapping originating from the generation of electron-hole pairs by the surface plasmon or impact ionization.