This study examined the effects of deposition temperature on Hf_(0.5)Zr_(0.5)O_(2)(HZO)thin films deposited using atomic layer deposition(ALD)with Tetrakis(ethylmethylamino)(TEMA)Hf,Zr,and cyclopentadienyl(CP)-linked ...This study examined the effects of deposition temperature on Hf_(0.5)Zr_(0.5)O_(2)(HZO)thin films deposited using atomic layer deposition(ALD)with Tetrakis(ethylmethylamino)(TEMA)Hf,Zr,and cyclopentadienyl(CP)-linked Hf,Zr precursors.The discrete feeding method was utilized to stabilize the growth per cycle,addressing challenges related to CP-linked precursors'high viscosity and molecular mass.The ALD temperature windows for HfO_(2)and ZrO_(2)films using the CP-linked precursors were 330-370℃and 290-330℃,respectively,higher than those using the TEMA precursors(250-280℃).Films deposited at higher temperatures with CP-linked precursors showed higher density and lower leakage currents than those with TEMA precursors,showing ferroelectric hysteresis loops from Hf_(0.5)Zr_(0.5)O_(2)(HZO)film at thicknesses as low as 5 nm without a wake-up process.In contrast,the film using TEMA precursor required a minimum thickness of 18 nm to exhibit similar properties.Crystallographic analysis revealed improved crystallization,larger grain sizes,and lower tensile stress in films deposited at higher temperatures.Also,in-situ crystallization was achievable for HZO films thicker than 6 nm when deposited at elevated temperatures.These findings demonstrate that higher temperature deposition by adopting CP-linked precursors enhances HZO thin film properties,making them suitable for advanced ferroelectric memory applications.展开更多
This study clarifies the influence of single-layer(TiN,HfN,W)and bi-layer(HfN/TiN,W/TiN)bottom electrodes(BEs)on the ferroelectric performance and reliability of the 10-nm-thick Hf_(0.5)Zr_(0.5)O_(2)(HZO)thin films.A ...This study clarifies the influence of single-layer(TiN,HfN,W)and bi-layer(HfN/TiN,W/TiN)bottom electrodes(BEs)on the ferroelectric performance and reliability of the 10-nm-thick Hf_(0.5)Zr_(0.5)O_(2)(HZO)thin films.A smaller thermal expansion coefficient in HfN or W imposes higher in-plane tensile stress on the HZO thin films,facilitating the polar orthorhombic(o-)phase fraction and enhancing remanent polarization(P_(r)).However,thicker interfacial layers formed when HfN or W single-layer BE and HZO contacted directly,leading to excessive leakage current and degraded ferroelectric performance.These excessive interfacial layers were effectively suppressed by inserting a thin(5 nm-20 nm)TiN layer on the HfN or W BEs.As a result,the HZO thin films on the HfN/TiN and W/TiN bi-layer BEs decrease the HZO grain size,facilitating the o-phase formation(increasing P_(r))and lowering the film's coercive field.However,the higher surface roughness of the W/TiN bi-layer BEs induced excessive leakage current and reliability degradation.In contrast,the HfN BEs with a 10-or 20-nm-thick upper TiN layer lower the surface roughness of the BEs,thereby eliminating the adverse effects.As a result,the HfN 40 nm/TiN 10 nm/HZO/TiN stack exhibited enhanced ferroelectric performance up to 10^(9)switching cycles with a lower cycling field of 2.7 MV/cm than the TiN 50 nm/HZO/TiN stack with a cycling field of 3.7 MV/cm.展开更多
基金supported by SK hynix Inc.under its Center of Material Research for Semiconductors(C-MRS)program.
文摘This study examined the effects of deposition temperature on Hf_(0.5)Zr_(0.5)O_(2)(HZO)thin films deposited using atomic layer deposition(ALD)with Tetrakis(ethylmethylamino)(TEMA)Hf,Zr,and cyclopentadienyl(CP)-linked Hf,Zr precursors.The discrete feeding method was utilized to stabilize the growth per cycle,addressing challenges related to CP-linked precursors'high viscosity and molecular mass.The ALD temperature windows for HfO_(2)and ZrO_(2)films using the CP-linked precursors were 330-370℃and 290-330℃,respectively,higher than those using the TEMA precursors(250-280℃).Films deposited at higher temperatures with CP-linked precursors showed higher density and lower leakage currents than those with TEMA precursors,showing ferroelectric hysteresis loops from Hf_(0.5)Zr_(0.5)O_(2)(HZO)film at thicknesses as low as 5 nm without a wake-up process.In contrast,the film using TEMA precursor required a minimum thickness of 18 nm to exhibit similar properties.Crystallographic analysis revealed improved crystallization,larger grain sizes,and lower tensile stress in films deposited at higher temperatures.Also,in-situ crystallization was achievable for HZO films thicker than 6 nm when deposited at elevated temperatures.These findings demonstrate that higher temperature deposition by adopting CP-linked precursors enhances HZO thin film properties,making them suitable for advanced ferroelectric memory applications.
基金supported by the National Research Foundation of Korea(Grant No.2020R1A3B2079882).
文摘This study clarifies the influence of single-layer(TiN,HfN,W)and bi-layer(HfN/TiN,W/TiN)bottom electrodes(BEs)on the ferroelectric performance and reliability of the 10-nm-thick Hf_(0.5)Zr_(0.5)O_(2)(HZO)thin films.A smaller thermal expansion coefficient in HfN or W imposes higher in-plane tensile stress on the HZO thin films,facilitating the polar orthorhombic(o-)phase fraction and enhancing remanent polarization(P_(r)).However,thicker interfacial layers formed when HfN or W single-layer BE and HZO contacted directly,leading to excessive leakage current and degraded ferroelectric performance.These excessive interfacial layers were effectively suppressed by inserting a thin(5 nm-20 nm)TiN layer on the HfN or W BEs.As a result,the HZO thin films on the HfN/TiN and W/TiN bi-layer BEs decrease the HZO grain size,facilitating the o-phase formation(increasing P_(r))and lowering the film's coercive field.However,the higher surface roughness of the W/TiN bi-layer BEs induced excessive leakage current and reliability degradation.In contrast,the HfN BEs with a 10-or 20-nm-thick upper TiN layer lower the surface roughness of the BEs,thereby eliminating the adverse effects.As a result,the HfN 40 nm/TiN 10 nm/HZO/TiN stack exhibited enhanced ferroelectric performance up to 10^(9)switching cycles with a lower cycling field of 2.7 MV/cm than the TiN 50 nm/HZO/TiN stack with a cycling field of 3.7 MV/cm.
