Effect of Post Metallization Annealing for La 2 O 3 Thin Film

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any recovery of VFB shift, but shifted VFB toward more negative side. Hence,this assumption does not seem to be correct. Another is the reactionbetween metal upper electrodes and rare earth oxides. In the case ofaluminum upper electrodes which realized a recovery of VFB shift, it isnatural to consider that aluminum oxides (Al2O3) or lanthanum aluminate(LaAlO3) was formed if there were some reactions between aluminum upperelectrodes and rare earth oxides. And this assumption seems to becomemuch more reasonable that these reactions formed aluminum oxides, notlanthanum aluminate. This assumption is well substantiated by three factsobtained by this investigation. One is a decrease of capacitance value afterPMA with aluminum upper electrodes compared to one of PDA. It is wellknown that aluminum oxides have the lower dielectric constant (8~10)compared to lanthanum aluminate (20~25) and rare earth oxides (15~30).The second is the fact that PMA with gold upper electrodes increased thecapacitance value in contrast to the case of PMA with aluminum upperelectrodes. The third is an effect of a recovery of VFB shift for Gd2O3 by PMAwith aluminum as described in sub-section 3.3.4. This result also greatlysupports this assumption. Therefore, it is conceivable that the formation ofaluminum oxides decreased the capacitance value. Another, and this is themost significant part, is the fact that aluminum oxides have the property ofshifting VFB toward positive side. Aluminum oxide has been widelyinvestigated as the one of the most promising and realistic next generationgate insulator material and this VFB shift toward positive side has beencommonly reported. And these reactions might occurred not only in thefilms but also at the interface between lanthanum oxides and aluminum, andthat reaction could increase the own film thickness. These assumptionsexplained up to this point is illustrated in Figure 4-3.Finally, it can be suggested that the formation of higher qualityaluminum oxides between rare earth oxides which have high dielectricconstant such as laminate structure could realize the zero flat band shiftwith preserving higher capacitance value.- 96 -
AluminumAl 2 O 3 or LaAlO 3Al Al AlLa 2 O 3AlAl 2 O 3 or LaAlO 3Dielectric ConstantAl 2 O 3 : 8~10LaAlO 3 : 20~25Dielectric ConstantAl 2 O 3 : 8~10LaAlO 3 : 20~25SiliconPMA with Al•Lower Capacitance Value•Confirmation of Effectsin the case of Gd 2 O 3Figure 4-3: Illustration of the mechanism of a VFB shift recovery- 97 -
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CONTENTSChapter 1 Introduction-----
Page 5 and 6:
Chapter 1Introduction-1 -
Page 7 and 8:
Miniaturization with a scaling fact
Page 9 and 10:
Table 1-2: Electrical Properties fo
Page 11 and 12:
LSI fabrication, such as activation
Page 13 and 14:
Table 1-4 shows the properties of t
Page 15 and 16:
1.3 Purpose of My StudyIt is consid
Page 17 and 18:
Chapter 2FabricationAndCharacteriza
Page 19 and 20:
2.1.1 1 Wet Cleaning Method of Sili
Page 21 and 22:
2.1.3 Molecular Beam Deposition (MB
Page 23 and 24:
2.1.4 Rapid Thermal Annealing (RTA)
Page 25 and 26:
2.1.5 Vacuum Evaporation MethodAlum
Page 27 and 28:
1 1 1 t 1 kTC = C + C = εε+ q ε
Page 29 and 30:
In C-V curve, the two type of hyste
Page 31 and 32:
2.2.2 Leakage Current Density-Volta
Page 33 and 34:
2.2.3 Ellipsometry MethodEllipsomet
Page 35 and 36:
3.1 IntroductionIn this chapter, th
Page 37 and 38:
3.3 Electrical Characteristics in t
Page 39 and 40:
Capacitance (µF/cm 2 )21Al/La O /
Page 41 and 42:
Current Density [A/cm 2 ]10 2 10 1A
Page 43 and 44:
3.3.2 Effects of Chemical Oxidation
Page 45 and 46:
3.3.3 Dependence on the Annealing T
Page 47 and 48:
Capacitance (µF/cm 2 )210Al_As-dep
Page 49 and 50: Capacitance (µF/cm 2 )210Al/La O /
Page 51 and 52: Al/La O / n-Si(100)/Al2 3 250 o C d
Page 53 and 54: As the summary of this sub-section,
Page 55 and 56: Current Density[A/cm 10 2 PDAAs-de
Page 57 and 58: Equivalent Oxide thickness [nm]32.5
Page 59 and 60: Figure 3-29 shows the plots of VFB
Page 61 and 62: 3.4.1.4 Dependence on the Ambience
Page 63 and 64: V Shift [V]FB0.60.40.20-0.2-0.4-0.6
Page 65 and 66: Capacitance (µF/cm 2 )21PDA 300 o
Page 67 and 68: case of aluminum electrodes as comp
Page 69 and 70: 3.4.2.2 Effects of Chemical Oxidati
Page 71 and 72: V Shift [V]FB-0.4-0.5-0.6-0.7-0.8-0
Page 73 and 74: 2.62.5EOT [nm]2.42.3As-depo.2.2PDA_
Page 75 and 76: Capacitance (µF/cm 2 )21Au_PMA_N2_
Page 77 and 78: 3.4.2.5 The comparison with the cas
Page 79 and 80: 3.4.3 Effects of PMA for Platinum U
Page 81 and 82: 4Pt/La O / n-Si(100)/Al2 3EOT [nm]3
Page 83 and 84: EOT [nm]2.82.62.42.221.81.6Pt/La O
Page 85 and 86: On the other hand, there was almost
Page 87 and 88: V Shift [V]FB0.2Pt/La O / n-Si(100)
Page 89 and 90: Capacitance (µF/cm 2 )21Pt/La O /
Page 91 and 92: Capacitance (µF/cm 2 )21Pt_As-depo
Page 93 and 94: Chapter 4Conclusions- 89 -
Page 95 and 96: 4.1.2 Summary of the Investigation
Page 97 and 98: Table 4-2: Summary of my investigat
Page 99: esults. The second is the time when
Page 103 and 104: AcknowledgementIn the first place,
Page 105 and 106: Reference[1] International Technolo
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Effect of Post Metallization Annealing for La 2 O 3 Thin Film

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