Deuterium-incorporated Gate Oxide of MOS Devices Fabricated by Using Deuterium Ion Implantation

이재성,Kevin L. Lear 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.7

In the aspect of metal-oxide-semiconductor (MOS) device reliability, deuterium-incorporated gate oxide could be utilized to suppress the wear-out that is combined with oxide trap generation. An alternative deuterium process for the passivation of oxide traps or defects in the gate oxide of MOS devices has been suggested in this study. The deuterium ion is delivered to the location where the gate oxide resides by using an implantation process and subsequent N2 annealing process at the back-end of metallization process. A conventional MOS field-effect transistor (MOSFET) with a 3-nm-thick gate oxide and poly-to-ploy capacitor sandwiched with 20-nm-thick SiO2 were fabricated in order to demonstrate the deuterium effect in our process. An optimum condition of ion implantation was necessary to account for the topography of the overlaying layers in the device structure and to minimize the physical damage due to the energy of the implanted ion. Device parameter variations, the gate leakage current, and the dielectric breakdown phenomenon were investigated in the deuterium-ion-implanted devices. We found the isotope effect between hydrogen- and deuterium-implanted devices and an improved electrical reliability in the deuterated gate oxide. This implies that deuterium bonds are generated effectively at the Si/SiO2 interface and in the SiO2 bulk.

MOSFET 게이트 산화막내 결함 생성 억제를 위한 효과적인 중수소 이온 주입

이재성(Jae-Sung Lee),도승우(Seung-Woo Do),이용현(Yong-Hyun Lee) 대한전자공학회 2008 電子工學會論文誌-SD (Semiconductor and devices) Vol.45 No.7

중수소 처리된 3 ㎚ 두께의 게이트 산화막을 갖는 MOSFET를 제조하여 정전압 스트레스 동안의 게이트 산화막의 열화를 조사하였다. 중수소 처리는 열처리와 이온 주입법을 사용하여 각각 이루어졌다. 열처리 공정을 통해서는 게이트 산화막내 중수소의 농도를 조절하기가 힘들었다. 게이트 산화막내에 존재하는 과잉 중수소 결합은 열화를 가속시키기 때문에, 열처리 공정을 행한 소자에서 신뢰성이 표준공정에 의한 소자에 비해 저하되고 있음을 확인하였다. 그러나 중수소 이온 주입 방법을 통해서는 소자의 신뢰성이 개선됨을 확인하였다. 스트레스에 의한 게이트 누설 전류 변화 및 구동 특성 변화는 게이트 산화막내의 중수소 농도와 관련이 있으며, 이러한 특성은 적절한 공정 조건을 갖는 이온 주입법을 통해 개선할 수 있었다. 특히, 큰 스트레스 전압의 PMOSFET에서 중수소의 효과가 뚜렷하게 나타났으며, 이는 “hot” 정공과 중수소의 반응과 관련이 있는 것으로 판단된다. Experiment results are presented for gate oxide degradation under the constant voltage stress conditions using MOSFETs with 3-㎚-thick gate oxides that are treated by deuterium gas. Two kinds of methods, annealing and implantation, are suggested for the effective deuterium incorporation. Annealing process was rather difficult to control the concentration of deuterium. Because the excess deuterium in gate oxide could be a precursor for the wear-out of gate oxide film, we found annealing process did not show improved characteristics in device reliability, compared to conventional process. However, deuterium implantation at the back-end process was effective method for the deuterated gate oxide. Device parameter variations as well as the gate leakage current depend on the deuterium concentration and are improved by low-energy deuterium implantation, compared to those of conventional process. Especially, we found that PMOSFET experienced the high voltage stress shows a giant isotope effect. This is likely because the reaction between “hot” hole and deuterium is involved in the generation of oxide trap.

중수소 이온 주입된 게이트 산화막을 갖는 MOSFET의 전기적 특성

이재성(Jae-Sung Lee) 大韓電子工學會 2010 電子工學會論文誌-SD (Semiconductor and devices) Vol.47 No.4

중수소 결합이 존재하는 게이트 산화막을 갖는 MOSFET는 일반 MOSFET에 비해 신뢰성이 개선된다고 알려져 있다. 본 연구에서는 MOS 소자의 게이트 산화막내에 중수소를 분포시키기 위해 새로운 중수소 이온 주입법을 제안하였다. MOS 소자를 구성하는 층간 물질 및 중수소가 분포할 위치에 따라 중수소 이온 주입 에너지는 다양하게 변하게 된다. 이온 주입 후 발생할 수 있는 물질적 손상을 방지하기 위해 후속 열처리 공정이 수반된다. 제조된 일반 MOSFET를 사용하여 제안된 중수소이온 주입을 통해 게이트 산화막내 계면 및 bulk 결함이 감소함을 확인하였다. 그러나 이온 주입으로 인해 실리콘 기판의 불순물 농도가 변화할 수 있으므로 이온 주입 조건의 최적화가 필요하다. 중수소 이온 주입된 MOSFET의 CV 및 IV 특성 조사를 통해 이온 주입으로 인한 트랜지스터의 성능 변화는 발생하지 않았다. MOSFET with deuterium-incorporated gate oxide shows enhanced reliability compared to conventional MOSFET. We present an alternative process whereby deuterium is delivered to the location where the gate oxide reside by an implantation process. Deuterium ions were implanted using two different energies to account for the topography of the overlaying layers and placing the D peak at the top of gate oxide. A short anneal at forming gas was performed to remove the D-implantation damage. We have observed that deuterium ion implantation into the gate oxide region can successfully remove the interface states and the bulk defects. But the energy and the dose of the deuterium implant need to be optimized to maintain the Si substrates dopant activation, while generating deuterium bonds inside gate oxide. CV and IV characteristics studies also determined that the deuterium implant dose not degrade the transistor performance.

Effects of α-Tocopherol on the Oxidative Stability and Incorporation of Deuterium in Volatiles from a Linoleic Acid-deuterium Model System

오수미,이창규,김서영,김미자,이재환 한국식품과학회 2016 Food Science and Biotechnology Vol.25 No.3

The effects of α-tocopherol on the oxidative stability and incorporation of deuterium in volatiles were evaluated in linoleic acid-water model systems treated at 60oC by analyzing headspace oxygen depletion, formation of lipid hydroperoxides, and profiles of headspace volatiles. Deuterium oxide accelerated the rates of linoleic acid oxidation compared to samples in deuterium-free water. As the concentration of α-tocopherol increased from 0 to 1500 ppm, the consumption of headspace oxygen and the formation of volatiles decreased, whereas the contents of lipid hydroperoxides did not decrease in the linoleic acid-water system. The mass to charge ratios (m/z) of volatiles in linoleic aciddeuterium oxide were significantly higher than those with deuterium oxide-free water. Generally, the presence of α-tocopherol decreased the mass to charge ratios (m/z) of volatiles including pentanal, hexanal, t-2-heptenal, and 2-octenal, implying that α-tocopherol may be involved in the aldehyde formation from lipid oxidation.

고압 중수소 열처리 효과에 의해 조사된 수소 결합 관련 박막 게이트 산화막의 열화

이재성 대한전자공학회 2004 電子工學會論文誌-SD (Semiconductor and devices) Vol.41 No.11

두께가 약 3 nm 인 게이트 산화막을 갖는 P 및 NMOSFET를 제조하여 높은 압력 (5 atm.)의 중수소 및 수소 분위기에서 후속 열처리를 각각 행하여 중수소 효과(동위원소 효과)를 관찰하였다. 소자에 대한 스트레스는 -2.5V ≤ V/sub g/ ≤-4.0V 범위에서 100℃의 온도를 유지하며 진행되었다. 낮은 스트레스 전압에서는 실리콘 계면에 존재하는 정공에 의하여 게이트 산화막의 열화가 진행되었다. 그러나 스트레스 전압을 증가시킴으로써 높은 에너지를 갖는 전자에 의한 계면 결함 생성이 열화의 직접적인 원인이 됨을 알 수 있었다. 본 실험조건에서는 실리콘 계면에서 phonon 산란이 많이 발생하여 impact ionization에 의한 "hot" 정공의 생성은 무시할 수 있었다. 중수소 열처리를 행함으로써 수소 열처리에 비해 소자의 파라미터 변화가 적었으며, 게이트 산화막의 누설전류도 억제됨이 확인되었다. 이러한 결과로부터 impact ionization이 발생되지 않을 정도의 낮은 스트레스 전압동안 발생하는 게이트 산화막내 결함 생성은 수소 결합과 직접적인 관계가 있음을 확인하였다. Experimental results are presented for the degradation of 3 nm-thick gate oxide under -2.5V $\leq$ V$_{g}$ $\leq$-4.0V stress and 10$0^{\circ}C$ conditions using P and NMOSFETs that are annealed with hydrogen or deuterium gas at high-pressure (5 atm). The degradation mechanisms are highly dependent on stress conditions. For low gate voltage, hole-trapping is found to dominate the reliability of gate oxide both in P and NMOSFETs. With increasing gate voltage to V$_{g}$ =-4.0V, the degradation becomes dominated by electron-trapping in NMOSFETs, however, the generation rate of "hot" hole was very low, because most of tunneling electrons experienced the phonon scattering before impact ionization at the Si interface. Statistical parameter variations as well as the gate leakage current depend on and are improved by high-pressure deuterium annealing, compared to corresponding hydrogen annealing. We therefore suggest that deuterium is effective in suppressing the generation of traps within the gate oxide. Our results therefore prove that hydrogen related processes are at the origin of the investigated oxide degradation.gradation.

중수소 이온 주입에 의한 MOS 커패시터의 게이트 산화막 절연 특성 개선

서영호,도승우,이용현,이재성,Seo, Young-Ho,Do, Seung-Woo,Lee, Yong-Hyun,Lee, Jae-Sung 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.8

This paper is studied for the improvement of the characteristics of gate oxide with 3-nm-thick gate oxide by deuterium ion implantation methode. Deuterium ions were implanted to account for the topography of the overlaying layers and placing the D peak at the top of gate oxide. A short anneal at forming gas to nitrogen was performed to remove the damage of D-implantation. We simulated the deuterium ion implantation to find the optimum condition by SRIM (stopping and range of ions in matter) tool. We got the optimum condition by the results of simulation. We compare the electrical characteristics of the optimum condition with others terms. We also analyzed the electrical characteristics to change the annealing conditions after deuterium ion implantation. The results of the analysis, the breakdown time of the gate oxide was prolonged in the optimum condition. And a variety of annealing, we realized the dielectric property that annealing is good at longer time. However, the high temperature is bad because of thermal stress.

Volatile profiles and involvement step of moisture in bulk oils during oxidation by action of deuterium oxide (D2O)

이찬규,이보라,김성화,최형석,김미자,이재환 한국식품과학회 2018 Food Science and Biotechnology Vol.27 No.5

Volatile formation is an inevitable result of lipid oxidation, which impact the quality of lipid rich foods. In this study, moisture role on the formation of volatiles were evaluated using deuterium oxide (D2O) and possible steps of moisture involvement were suggested. Moisture content in corn oil with deuterium free water (H2O) was significantly (p\0.05) higher than that in corn oil with D2O. The contents of some volatiles including pentane, hexanal, 2-hexenal, and t-2-heptenal in corn oil with D2O were higher than those in corn oil with H2O for the first 8 days. Volatiles containing deuterium appeared in the order of pentane, t-2-pentenal, and t-2-heptenal during oxidation. Deuterium incorporated volatiles could be formed after the b-scission of lipid hydroperoxides. Therefore, moisture plays important roles in the formation of volatiles as well as the locations of oxidation in bulk oils.

박막 게이트 산화막을 갖는 n-MOSFET에서 SILC 및 Soft Breakdown 열화동안 나타나는 결함 생성

이재성 대한전자공학회 2004 電子工學會論文誌-SD (Semiconductor and devices) Vol.41 No.8

Experimental results are presented for gate oxide degradation, such as SILC and soft breakdown, and its effect on device parameters under negative and positive bias stress conditions using n-MOSFET's with 3 nm gate oxide. The degradation mechanisms are highly dependent on stress conditions. For negative gate voltage, both interface and oxide bulk traps are found to dominate the reliability of gate oxide. However, for positive gate voltage, the degradation becomes dominated mainly by interface trap. It was also found the trap generation in the gate oxide film is related to the breakage of Si-H bonds through the deuterium anneal and additional hydrogen anneal experiments. Statistical parameter variations as well as the “OFF” leakage current depend on both electron- and hole-trapping. Our results therefore show that Si or O bond breakage by tunneling electron and hole can be another origin of the investigated gate oxide degradation. This plausible physical explanation is based on both Anode-Hole Injection and Hydrogen-Released model. 두께가 3nm인 게이트 산화막을 사용한 n-MOSFET에 정전압 스트레스를 가하였을 때 관찰되는 SILC 및 soft breakdown 열화 및 이러한 열화가 소자 특성에 미치는 영향에 대해 실험하였다. 열화 현상은 인가되는 게이트 전압의 극성에 따라 그 특성이 다르게 나타났다. 게이트 전압이 (-)일 때 열화는 계면 및 산화막내 전하 결함에 의해 발생되었지만, 게이트 전압이 (+)일 때는 열화는 주로 계면 결함에 의해 발생되었다. 또한 이러한 결함의 생성은 Si-H 결합의 파괴에 의해 발생할 수 있다는 것을 중수소 열처리 및 추가 수소 열처리 실험으로부터 발견하였다. OFF 전류 및 여러 가지 MOSFET의 전기적 특성의 변화는 관찰된 결함 전하(charge-trapping)의 생성과 직접적인 관련이 있다. 그러므로 실험 결과들로부터 게이트 산화막으로 터널링되는 전자나 정공에 의한 Si 및 O의 결합 파괴가 게이트 산화막 열화의 원인이 된다고 판단된다. 이러한 물리적 해석은 기존의 Anode-Hole Injection 모델과 Hydrogen-Released 모델의 내용을 모두 포함하게 된다.

Microstructure evolution and effect on deuterium retention in oxide dispersion strengthened tungsten during He⁺ irradiation

Ding, Xiao-Yu,Xu, Qiu,Zhu, Xiao-yong,Luo, Lai-Ma,Huang, Jian-Jun,Yu, Bin,Gao, Xiang,Li, Jian-Gang,Wu, Yu-Cheng Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.12

Oxide dispersion-strengthened materials W-1wt%Pr₂O₃ and W-1wt%La₂O₃ were synthesized by wet chemical method and spark plasma sintering. The field emission scanning electron microscopy (FE-SEM) analysis, XRD and Vickers microhardness measurements were conducted to characterize the samples. The irradiations were carried out with a 5 keV helium ion beam to fluences up to 5.0 × 10²¹ ions/m² under 600 ℃ using the low-energy ion irradiation system. Transmission electron microscopy (TEM) study was performed to investigate the microstructural evolution in W-1wt%Pr₂O₃ and W-1wt%La₂O₃. At 1.0 × 10²⁰ He⁺/m², the average loops size of the W-1wt%Pr₂O₃ was 4.3 nm, much lower than W-1wt% La₂O₃ of 8.5 nm. However, helium bubbles were not observed throughout in both doped W materials. The effects of pre-irradiation with 1.0 × 10²¹ He⁺/m² on trapping of injected deuterium in doped W was studied by thermal desorption spectrometry (TDS) technique using quadrupole mass spectrometer. Compared with the samples without He⁺ pre-irradiation, deuterium (D) retention of doped W materials increased after He⁺ irradiation, whose retention was unsaturated at the damage level of 1.0 × 10²²D₂⁺/m². The present results implied that irradiation effect of He⁺ ions must be taken into account to evaluate the deuterium retention in fusion material applications.

Effects of Deuterium Oxide on Formation of Volatiles in Linoleic Acid Model Systems at Different Temperatures and Oxygen Limitation Conditions

오수미,이보라,김미자,이재환 한국식품과학회 2015 Food Science and Biotechnology Vol.24 No.1

Effects of 30, 60, and 90℃ treatments and oxygen limitation on formation of volatiles were determined for linoleic acid model systems containing deuterium oxide (D2O) and deuterium free water. The presence of D2O accelerated consumption of headspace oxygen, indicating that the rate of lipid oxidation increased in the presence of D2O. The presence of deuterium in headspace volatiles was indirectly determined based on comparison of the amount of the fragmented mass to charge ratio (m/z) (molecular weight, Mw), which was 73.1/72.1 for d1-pentane/pentane and 125.1/124.1 for d1-2,4 octadienal/2,4 octadienal. The ratio of 73.1/72.1 (m/z) for pentane was significantly (p<0.05) higher for samples containing D2O than for samples containing deuterium free water at 30, 60, and 90℃. Other volatiles did not follow the same pattern. 2,4-Octadienal in samples under unlimited oxygen conditions confirmed this trend, indicating that water was incorporated into volatiles during oxidation of linoleic acid under these conditions.