DRAM의 technology는 고집적화, 고스피드, 저전력 소자로 발전하고 있다. Tech node감소에 따른 단위 cell 면적의 감소로 data가 저장되는 storage node의 pitch도 지속적으로 감소되고 있다. 또한, 10nm급 tech node에서는 기존의 cylinder type의 capacitor에서 pillar type의 capacitor로 전환되어 cell capacitor의 면적이 급격히 감소하였다. 그러나, DRAM cell capacitor에 저장된 data를 sense amplifier에서 정확히 읽고 다시 쓰기 위해서는 cell capacitor에 일정량 이상의 charge를 저장하여야 한다. 따라서, cell capacitor의 dielectric layer로high-k 물질의 개발이 점점 중요해지고 있다. 본 논문에서는 ...
DRAM의 technology는 고집적화, 고스피드, 저전력 소자로 발전하고 있다. Tech node감소에 따른 단위 cell 면적의 감소로 data가 저장되는 storage node의 pitch도 지속적으로 감소되고 있다. 또한, 10nm급 tech node에서는 기존의 cylinder type의 capacitor에서 pillar type의 capacitor로 전환되어 cell capacitor의 면적이 급격히 감소하였다. 그러나, DRAM cell capacitor에 저장된 data를 sense amplifier에서 정확히 읽고 다시 쓰기 위해서는 cell capacitor에 일정량 이상의 charge를 저장하여야 한다. 따라서, cell capacitor의 dielectric layer로high-k 물질의 개발이 점점 중요해지고 있다. 본 논문에서는 ZrO2박막 내에 Ga을 doping하여 박막 내 oxygen vacancy의 양을 증가시키고, 이를 통해 유전상수가 높은 결정상인 tetragonal phase를 강화시키고자 하였다. ZrO2 박막 내 Ga doping은 ALD장비의 super cycle process를 이용하여 ZrO2와 Ga2O3 layer를 laminate 방식으로 증착하였다. (ZrO2)1-x(Ga2O3)x 박막의 Ga함량을 조절하기 위해 ZrO2:Ga2O3의 증착 cycle 비 n:1에서 n=2.5부터 43까지 변경하며 박막을 증착하였다. 이후 Zr:Ga 증착 cycle 비에 따른 Ga-doped ZrO2 박막의 결정성 및 lattice constant의 변화를 GIXRD를 통해 분석하였으며, Ga함량, Zr, O의 binding state 및 chemical shift를 XPS 분석을 통해 확인하였다. 그리고, capacitance-voltage(C-V), current-voltage(I-V) 측정을 통해 Ga의 함량에 따른 dielectric constant 및 leakage current 변화를 확인하였다. 이후 dielectric 내 oxygen vacancy 증가의 영향을 확인하기 위해 온도별, bias별 leakage current를 측정하여 conduction mechanism을 분석하였다. 그 결과, Ga(2.3wt%)-doped ZrO2조건에서 leakage current 증가없이 dielectric constant가 ZrO2의 32대비 34.1로 6.5% 증가하였다. XPS 분석을 통해 Zr3d5/2의 binding energy가 ~0.17eV가량 낮은 energy로 이동하였으며, O1s 내 oxygen vacancy의 portion이 ~5.6% 증가하였음을 확인할 수 있었다. 그리고 GIXRD 분석을 통해서 lattice constant, Lc 및 unit cell volume의 감소와 tetragonal phase가 강화되었음을 확인하였다. 마지막으로 Arrhenius plot으로부터 박막 내 존재하는 trap의 energy level을 분석한 결과, Ga(2.3wt%)-doped ZrO2 박막에서의 trap energy level이 ~0.515eV로 ZrO2 박막 대비 ~0.07eV 가량 shallow trap을 형성한 것을 확인할 수 있었다.
DRAM의 technology는 고집적화, 고스피드, 저전력 소자로 발전하고 있다. Tech node감소에 따른 단위 cell 면적의 감소로 data가 저장되는 storage node의 pitch도 지속적으로 감소되고 있다. 또한, 10nm급 tech node에서는 기존의 cylinder type의 capacitor에서 pillar type의 capacitor로 전환되어 cell capacitor의 면적이 급격히 감소하였다. 그러나, DRAM cell capacitor에 저장된 data를 sense amplifier에서 정확히 읽고 다시 쓰기 위해서는 cell capacitor에 일정량 이상의 charge를 저장하여야 한다. 따라서, cell capacitor의 dielectric layer로high-k 물질의 개발이 점점 중요해지고 있다. 본 논문에서는 ZrO2 박막 내에 Ga을 doping하여 박막 내 oxygen vacancy의 양을 증가시키고, 이를 통해 유전상수가 높은 결정상인 tetragonal phase를 강화시키고자 하였다. ZrO2 박막 내 Ga doping은 ALD장비의 super cycle process를 이용하여 ZrO2와 Ga2O3 layer를 laminate 방식으로 증착하였다. (ZrO2)1-x(Ga2O3)x 박막의 Ga함량을 조절하기 위해 ZrO2:Ga2O3의 증착 cycle 비 n:1에서 n=2.5부터 43까지 변경하며 박막을 증착하였다. 이후 Zr:Ga 증착 cycle 비에 따른 Ga-doped ZrO2 박막의 결정성 및 lattice constant의 변화를 GIXRD를 통해 분석하였으며, Ga함량, Zr, O의 binding state 및 chemical shift를 XPS 분석을 통해 확인하였다. 그리고, capacitance-voltage(C-V), current-voltage(I-V) 측정을 통해 Ga의 함량에 따른 dielectric constant 및 leakage current 변화를 확인하였다. 이후 dielectric 내 oxygen vacancy 증가의 영향을 확인하기 위해 온도별, bias별 leakage current를 측정하여 conduction mechanism을 분석하였다. 그 결과, Ga(2.3wt%)-doped ZrO2조건에서 leakage current 증가없이 dielectric constant가 ZrO2의 32대비 34.1로 6.5% 증가하였다. XPS 분석을 통해 Zr3d5/2의 binding energy가 ~0.17eV가량 낮은 energy로 이동하였으며, O1s 내 oxygen vacancy의 portion이 ~5.6% 증가하였음을 확인할 수 있었다. 그리고 GIXRD 분석을 통해서 lattice constant, Lc 및 unit cell volume의 감소와 tetragonal phase가 강화되었음을 확인하였다. 마지막으로 Arrhenius plot으로부터 박막 내 존재하는 trap의 energy level을 분석한 결과, Ga(2.3wt%)-doped ZrO2 박막에서의 trap energy level이 ~0.515eV로 ZrO2 박막 대비 ~0.07eV 가량 shallow trap을 형성한 것을 확인할 수 있었다.
DRAM technology is evolving into high integration, high speed, and low power devices. As the unit cell area decreases due to the shrinkage in the tech node, the pitch of the storage node where data is stored is also continuously decreasing. In addition, in the 10nm class tech node, the reduction in ...
DRAM technology is evolving into high integration, high speed, and low power devices. As the unit cell area decreases due to the shrinkage in the tech node, the pitch of the storage node where data is stored is also continuously decreasing. In addition, in the 10nm class tech node, the reduction in the area of the capacitor rapidly increased as the conventional cylinder type capacitor was converted to a pillar type capacitor. Since a certain amount of charge is required to read and write data to a DRAM cell, the development of a high-k dielectric is becoming increasingly important. In this paper, the amount of oxygen vacancy in the thin film is increased by doping Ga in the ZrO2 thin film, and through this, the tetragonal phase, which is a high dielectric constant crystal phase, is to be strengthened. For Ga doping in the ZrO2 thin film, ZrO2 and Ga2O3 layers were deposited in a laminate method using the super cycle process of ALD equipment. In order to control the Ga content of the (ZrO2)1-x(Ga2O3)x thin film, a thin film was deposited by changing the deposition cycle ratio of ZrO2:Ga2O3 from n:1 to n=2.5 to 43. Afterwards, the crystallinity of the Ga-doped ZrO2 thin film according to the Ga content in the ZrO2 thin film was analyzed through GIXRD, and the Ga composition, binding state and chemical shift of Zr, O were confirmed through XPS analysis. The dielectric constant and leakage current changes according to the Ga content were confirmed through measurement of capacitance-voltage (C-V) and current-voltage (I-V). Afterwards, the conduction mechanism was analyzed by measuring the leakage current by temperature to check the effect of the increase in oxygen vacancy in the dielectric. As a result, at a Zr:Ga doping cycle ratio of 21:1 (Ga content 2.3wt%), the dielectric constant increased by 6.5% to 34.1 compared to 32 of ZrO2 without an increase in leakage current at room temperature. According to XPS analysis, the binding energy of Zr3d5/2 moved to a low energy by ~0.17 eV, and the oxygen vacancy portion in O1s increased by ~5.6%. In addition, as a result of GIXRD analysis, it was confirmed that the lattice constant, Lc and unit cell volume were decreased, and the tetragonal phase was strengthened. And activation energy, E_a(〖(Φ〗_T,V=0) was calculated from the leakage current measured by temperature and bias to analyze the effect of increased oxygen vacancy in the ZrO2 thin film. As a result, it was confirmed that the trap energy level in the Ga(2.3wt%)-doped ZrO2 thin film was ~0.515eV, which formed a shallow trap of ~0.07eV compared to the ZrO2 thin film.
DRAM technology is evolving into high integration, high speed, and low power devices. As the unit cell area decreases due to the shrinkage in the tech node, the pitch of the storage node where data is stored is also continuously decreasing. In addition, in the 10nm class tech node, the reduction in the area of the capacitor rapidly increased as the conventional cylinder type capacitor was converted to a pillar type capacitor. Since a certain amount of charge is required to read and write data to a DRAM cell, the development of a high-k dielectric is becoming increasingly important. In this paper, the amount of oxygen vacancy in the thin film is increased by doping Ga in the ZrO2 thin film, and through this, the tetragonal phase, which is a high dielectric constant crystal phase, is to be strengthened. For Ga doping in the ZrO2 thin film, ZrO2 and Ga2O3 layers were deposited in a laminate method using the super cycle process of ALD equipment. In order to control the Ga content of the (ZrO2)1-x(Ga2O3)x thin film, a thin film was deposited by changing the deposition cycle ratio of ZrO2:Ga2O3 from n:1 to n=2.5 to 43. Afterwards, the crystallinity of the Ga-doped ZrO2 thin film according to the Ga content in the ZrO2 thin film was analyzed through GIXRD, and the Ga composition, binding state and chemical shift of Zr, O were confirmed through XPS analysis. The dielectric constant and leakage current changes according to the Ga content were confirmed through measurement of capacitance-voltage (C-V) and current-voltage (I-V). Afterwards, the conduction mechanism was analyzed by measuring the leakage current by temperature to check the effect of the increase in oxygen vacancy in the dielectric. As a result, at a Zr:Ga doping cycle ratio of 21:1 (Ga content 2.3wt%), the dielectric constant increased by 6.5% to 34.1 compared to 32 of ZrO2 without an increase in leakage current at room temperature. According to XPS analysis, the binding energy of Zr3d5/2 moved to a low energy by ~0.17 eV, and the oxygen vacancy portion in O1s increased by ~5.6%. In addition, as a result of GIXRD analysis, it was confirmed that the lattice constant, Lc and unit cell volume were decreased, and the tetragonal phase was strengthened. And activation energy, E_a(〖(Φ〗_T,V=0) was calculated from the leakage current measured by temperature and bias to analyze the effect of increased oxygen vacancy in the ZrO2 thin film. As a result, it was confirmed that the trap energy level in the Ga(2.3wt%)-doped ZrO2 thin film was ~0.515eV, which formed a shallow trap of ~0.07eV compared to the ZrO2 thin film.
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