A1258150210BZoQP

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Crystalline forms quartz, cristobalite,
tridymite Amorphous silica (brand name, can be
mixed) Methods of preparation Deposition Therma
l oxidation
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The oxygen atoms are electronegative, and some
of the silicon valence electron density is
transferred to the oxygen neighbors,
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The Si-O distance is 1.61 A (0.16 nm) which is
slightly smaller than the sum of the covalent
"radii" of the atoms Si (0.11 nm) O(0.066 nm)
0.18 nm
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• The result of this flexibility in the bridge
  bonds is that SiO2 can easily form amorphous
  materials
• amorphous silicon dioxide will not crystallize
  upon annealing at normal temperatures. (process
  known as "Devitrification" )

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The amorphous structure is tends to be very
"open" even in thermally-grown oxides, channels
exist through which small positive ions such as
Na and K can readily migrate. These ions can
move under the influence of electric fields
within the gate oxides of MOS transistors,
causing shifts in the voltage at which the
transistor turns on ("threshold shifts").
Exclusion of such ions is imperative for reliable
operation of MOS transistors and integrated
circuits.
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r, density 2.0-2.3 gm/cm3 s varies
widely EBV gt1E7 V/cm in thermal oxides Thermal
conductivity 0.01 W/cm K (bulk) Thermal
diffusivity 0.009 cm2/sec (bulk) CTE
0.5 ppm/ K n 1.46 thermal oxide er
3.9 thermal oxide note properties of
CVD oxides vary widely depending on H
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• The first reaction has little change in enthalpy
  and is nearly reversible locally strained bonds,
  with reduced bond energy, are particularly
  vulnerable to attack by water ("hydrolysis").
  Oxides containing large amounts of SiOH are more
  hygroscopic, and readily adsorb water molecules
  from the air.
• The water can migrate through the deposited
  materials to the gate oxide, there causing drifts
  in performance of transistors under bias,
  impairing hot electron reliability, also known as
  gate oxide integrity or GOI. The water molecules
  can, however, be consumed by the reactions with
  Si-H groups this is the basis of the use of
  silicon-rich oxides as water getters or barriers.

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• Phosphosilicate glass (PSG) flows readily at 1000
  C for 6-8 weight P
• Borophosphosilicate glass (BPSG) can achieve a
  lower flow temperature typically around 900 C
  for 4-5 wt. of each dopant. (notethat 4 weight
  of boron is a very large mole percentage --
  around 12 at. depending on composition-- because
  B atoms are so light.)

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SiO2 CVD from Silane oxygen
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SiO2 CVD from Silane oxygen
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SiO2 CVD from Silane oxygen (3)
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Magnetic enhancement
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TEOS-Tetra Ethyle Ortho SIlicate
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TEOS CVD
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TEOS - CVD (3)
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TEOS OZONE CVD
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TiN byproducts
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TiN byproducts
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Diffusion barrier comparison, (M. Mossavi et al.,
IITC 98)
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MOCVD TiN Precursors Tetrakis-dimethylamino
Titanium
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Ternary phase diagrams

• The lack of Ta-Cu compounds yield a broad range
  of compositions in equilibrium with Cu.
• Ti-rich compositions are expected to react with Cu

N
TaN Ta2N
Ti
Cu
Ta
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High K materials (I)
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