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

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3.4 Electrical Characteristics in the case of PMAIn the pages that follow, the result of post metallization annealing(PMA) will be mainly described. Especially, VFB shift after annealing andcomparison with PDA were focused.3.4.1 Effects of PMA for Aluminum Upper ElectrodesFor examination of PMA, a choice of upper electrodes material is quitesignificant because La2O3 films are supposed to be done staying contact withupper metal electrodes during thermal process and that might bring somereaction which affect electrical characteristics. In this sub-section, PMAwith Aluminum upper electrodes were investigated.3.4.1.1 Dependence on the Temperature of PMA with AluminumUpper ElectrodesFirst, dependence on the temperature of PMA was investigated.Figure 3-16 shows the C-V characteristics dependent on the temperature ofPMA for La2O3 thin films with Al electrodes. All of PMA samples wereHF-last treatment and annealed in nitrogen ambience for 10 minutes.Annealing temperature from 200 o C to 450 o C was examined respectively. Itwas confirmed that PMA at 300 o C with aluminum upper electrodes made itpossible to recover the negative VFB shift. However, it was found that PMAwith Aluminum electrodes in the case of temperature higher than 300 o Cdegraded electrical characteristics, causing such as an increase of hysteresisor a decrease of capacitance value. On the other hand, it was also foundthat PMA with Aluminum electrodes in the case of temperature lower than300 o C did not make electrical characteristics improve sufficiently such asslight VFB shift toward negative side or a drop of capacitance value inaccumulation region.- 44 -
Capacitance (µF/cm 2 )210Al/La O / n-Si(100)/Al2 3 250 o C depo. HF-lastAs-depo. & PMA200 o C to 450 o C10min.N ambient2as-depo.450 o C400 o C300 o C200 o CIdeal V FB-1.5 -1 -0.5 0 0.5 1Voltage (V)Figure 3-16: C-V characteristics dependent on temperature of PMA processFigure 3-17 shows frequency dependence on C-V characteristics ofPMA samples annealed from 200 o C to 450 o C respectively. It can beobserved that frequency dependence at weak inversion became largersuddenly from PMA at 400 o C. And, to make matters worse, C-Vcharacteristics could not maintain its figure in the case of PMA at 450 o C.This result indicates that PMA at higher temperature increased the interfacestate density. At the same time, it also indicates that some reactions tookplace by PMA with aluminum and that reactions seriously affected theelectrical characteristics. The consideration about this reaction will comeup later. Figure 3-18 shows the J-V characteristics dependent ontemperature of PMA. Temperature from 200 o C to 450 o C as-depositedsamples was examined. It was confirmed that leakage current increasedwith increase of annealing temperature as it were the substantiation of anincrease of the interface state density. However, low leakage current wasmaintained by PMA at 300 o C. And it was also confirmed PMA at 200 o C wasnot a sufficient temperature to suppress the leakage current.- 45 -
Page 2: 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: Capacitance (µF/cm 2 )210Al_As-dep
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 and 100:
esults. The second is the time when
Page 101 and 102:
AluminumAl 2 O 3 or LaAlO 3Al Al Al
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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