27.2.9 TOF-SIMS
SIMS TOF-SIMS SIMS Mass Spectrometer ABCDE + ABC+ DE + Primary Ions: 1 12 ions/cm 2 Molecular Fragmentation Region ABCDE ABCDE 1 15 atoms/cm 2 Molecular Desorption Region Why TOF-SIMS?
TOF-SIMS - 3 7 8 - - M/ M 1 - M 1 mamu M/M 1 ppm M 1 amu - Ga + Au n+ D-SIMS
TOF-SIMS
TOF-SIMS SIMS SIMS Damage cross section Precursor model - - Damage cross section Damage cross section Au TOF-SIMS
SIMS Damage Cross Section; Disappearance Cross Section Damage cross section σ 1 SIMS
SIMS Damage Cross Section; Disappearance Cross Section lnn(counts) Θ(t)=Θ exp[-σνt] ν=i P /Ae Θ: N I P A: e σ σ νt (ions/cm 2 ) t(sec) or νt(ions/cm 2 ) νt 1/σ σ=1-14 1-15 cm 2 νt <1 12 1 13 ions/cm 2
SIMS /Ag D. van Leyen et al., J. Vac. Sci. Technol. A7(3), 179 (1989) m/z 22 6: Ag-cationized oligomers, (nr+ag) + R: repeat unit with m=14 amu
SIMS /Ag Disappearance cross section, σ σ m=1 σ = 3 1-13 cm 2 3n m=69 σ = 1.7 1-12 cm 2 7nm
Precursor model Desorption active area A D E(r): E D : r R E(r) E r R D E(r) E D A D R r R D Precursor : Preformed ion
(counts/channel) 1 5 1 5 1 5 1 5 3 1 NO 2 SO C 3 3 H 29 9 Si + C 4 H 12 N + 2 5 C 2 H 6 SiO + 1 74. 74.1 74. 74.1 74. 74.1 74. 74.1 45.9 46. 1 5 1 5 1 5 45.9 46. 45.9 46. 45.9 46. m/z 1 79.9 8. 8.1 5 1 79.9 8. 8.1 5 79.9 8. 8.1 1 5 79.9 8. 8.1 NO x SO x UV ( 5 ) (18 5 ) UV + (18 5 )
28 Si - 1.5 PP DHF PP DHF ( 4) ( 2) ( 8) 13 CH - 25 C 2 H - 227 C 14 H 27 O 2-255 C 16 H 31 O 2-283 C 18 H 35 O 2 -
Precursor model E(r): E D : σ E D D.Rading et al., J. Vac. Sci. Technol. A 18(2), 312 (2) A D : Desorption active area E D σ σ
Desorption energy E D, damage cross section σ, and the distance r from the point of primary ion impact Thiol E D /ev σ/1-16 cm 2 r /nm BT(n=4) 1.36 57.43 HT(n=6) 1.35 89.53 OT(n=8) 1.33 112.6 DT(n=1) 1.3 96.55 DDT(n=12) 1.38 65.45 BDT(n=14) 1.45 48.39 HDT(n=16) 1.42 47.39 ODT(n=18) 1.47 38.35 TSA (M-H) - 1.6 35.33 TSA (M-COOH) - 1.71 17.23 MCP (M-H) - 1.85 4.11 /Au σ 1-14 1-16 cm 2 Alkanethiol n=8 1 σ E D σ σ E D 1.3 2eV σ
Desorption active area A D
vs. B TOF-SIMS νt=1.7 1 12 ions/cm 2, A=1 m (a) 69 Ga + SF 5+, Au n+, Bi n+, (CsI) n Cs +, C 6+, ReO 4, etc. (b) 115 In +
TOF-SIMS SIMS SIMS Damage cross section Precursor model - - Damage cross section Damage cross section Au TOF-SIMS
Au Si Primary Ion: Au 3 + 1µm Total ion SiH x O y - 85 C 4 H 5 O 2-185 C 9 H 13 O 4 - Primary Ion: Ga + 1µm Total ion SiH x O - y 85 C 4 H 5 O - 2 185 C 9 H 13 O - 4 TOF-SIMS images of Si wafer surface with the foreign substance.
Intensity (counts) 1 3 1.2 1..8.6.4.2 1 4.8.6.4.2 O - CH - O - 8 O 85 - O 141 1 2 3 O - CH 3 O - 1 CH - SiHO - 3 85 Au Si O - O 1 M / Z 2 3 OCH 3 185 O OCH 3 Primary Ion: Au 3 + O - OCH 3 Primary Ion: Ga + Ga + 85 C 4 H 5 O 2- Au 3+ 85 C 4 H 5 O 2-141 C 8 H 13 O 2-185 C 9 H 13 O 4-
Au Intensity (counts) 1 4 C 4 H 7 + C 3 H + 6. 5 4. 2. HO CH 2 5 219 322 352 HO N N N OH C 5 H 11 C 5 H 11 CH 2 OH 569 HO 774 OH OH Intensity (counts) 1E7 1E6 1E5 1E4 1E3 1E2 1E1 1E 2 4 6 8 1 M / Z Ga + Au + Au + 3 Ca + Ba + 15 CH + 41 3 C 3 H +219 5 C 15 H 23 O + 569 C 4 H 57 O + 352 2 C 22 H 3 N 3 O + 774 C 54 H 78 O + 3
Influence of primary ion bombardment conditions on the emission of molecular secondary ions R.Kersting et al., Appl. Surf. Sci. 231/232, 261(24)
Molecular secondary ion formation under cluster bombardment: A fundamental review A.Wucher, Appl. Surf. Sci. 252, 6482(26) C 6+ Erosion depth > Range?!
C 6+ J.Cheng et al., Anal Chem. 77, 3651(25)
SIMS Damage cross section Molecular imaging SIMS Damage cross section
TOF-SIMS SIMS SIMS Damage cross section Precursor model - - Damage cross section Damage cross section Au TOF-SIMS
TOF-SIMS SIMS - Damage cross section - - - -