Specific Process Knowledge/Thermal Process/Oxidation

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Oxidation

At Danchip we have sevem furnaces for oxidation of silicon samples: Boron Drive-in + Pre-dep furnace (A1), Gate Oxide furnace (A2). Phosphorous Drive-in furnace (A3), Anneal-oxide furnace (C1), Anneal-Bond furnace (C3), APOX furnace (D1) and Multipurpose Annealing furnace.

Oxidation can take place either by a dry process or a wet process, depending on what furnace that is used for the oxidation. The film quality for a dry oxide is better than the film quality for a wet oxide with regards to density and dielectric constant. However, the oxidation rate is slow for a dry oxide.

  • Dry oxidation is used for 5 nm - 200 nm of oxide and can be grown in the furnaces: A1, A2, A3, C1, C3, Multipurpose Annealing
  • Wet oxidation is used for up to 4 µm of oxide and can be grown in the furnaces: A1, A3, D1.
  • Very thick oxide layers >4 µm can be grown in D1 by a wet oxidation (only performed by Danchip).

The standard recipes, quality control limits and results for the Boron Drive-in + Pre-dep furnace (A1) and the Phosphorus Drive-in furnace (A3) can be found here:

The wet oxidation rates for the Anneal-Bond furnace (C1) can be found here:

Comparison of the seven oxidation furnaces

Boron Drive-in + Pre-dep furnace (A1)

Gate Oxide furnace (A2)

Phosphorous Drive-in furnace (A3)

Anneal Oxide furnace (C1)

Anneal Bond furnace (C3)

APOX furnace (D1)

Multipurpose Annealing furnace

Generel description Dry and wet oxidation. Boron pre-deposition and boron drive-in of boron are also done in the furnace. Dry oxidation of gate oxide and other very clean oxides. Dry and wet oxidation. Phosphorous drive-in is also done in the furnace. Dry and wet oxidation of 100 mm and 150 mm wafers. Oxidation of new wafers without RCA cleaning. Oxidation and annealing of wafers from the LPCVD furnaces and PECVD4. Dry and wet oxidation and annealing of wafers from Wafer Bonder 02 and from PECVD4 and PECVD3. Wet oxidation of very thick oxides > 4 µm. Dry oxidation and annealing of almost all materials.
Oxidation method
  • Dry: O2
  • Wet: Torch
  • Dry: O2
  • Dry: O2
  • Wet: Torch
  • Dry: O2
  • Wet: Steamer
  • Dry: O2
  • Wet: Bubbler
  • Wet: Bubbler
  • Dry: O2
Annealing gas
  • N2
  • N2
  • N2
  • N2
  • N2
  • N2
  • N2
  • H2
Process temperature
  • 900 oC - 1150 oC
  • 900 oC - 1150 oC
  • 900 oC - 1150 oC
  • 900 oC - 1100 oC
  • 900 oC - 1150 oC
  • 1075 oC
  • Vacuum: 20 oC - 1050 oC
  • No vacuum: 20 oC - 1100 oC
Substrate and batch size
  • 1-30 50 mm wafers
  • 1-30 100 mm wafers
  • 1-30 50 mm wafers
  • 1-30 100 mm wafers
  • 1-30 50 mm wafers
  • 1-30 100 mm wafers
  • Small samples on a carrier wafer, horizontal
  • 1-30 50 mm wafers
  • 1-30 100 mm wafers
  • 1-30 150 mm wafers
  • Small samples on a carrier wafer, horizontal
  • 1-30 50 mm wafers
  • 1-30 100 mm wafers
  • 1-150 100 mm wafers
  • 1-30 50 mm, 100 mm or 150 mm wafers
  • 1-50 200 mm wafers
  • Small samples on a carrier wafer, horizontal
Allowed materials
  • All wafers have to be RCA cleaned, except boron pre-doped wafers from the same furnace.
  • All wafers have to be RCA cleaned.
  • All wafers have to be RCA cleaned, except phosphorous pre-doped wafers from furnace A4.
  • All processed wafers have to be RCA cleaned, except wafers from LPCVD furnaces and PECVD4.
  • All processed wafers have to be RCA cleaned, except for wafers from Wafer Bonder 02 and from PECVD4 and PECVD3.
  • Only new wafers
  • Depends on the furnace quartz set:
    • Metal: Almost all materials, permission is needed
    • Resist pyrolysis


Oxidation curves

Color chart for oxide/nitride thickness

Generic calculator for wet/dry oxide thickness calculation

The following links give an approximate oxide time/thickness based on a general formula:

Deal-Grove parameters

By Kasper Reck-Nielsen February 2015

The following table contains linear and parabolic parameters for use in the Deal-Grove model for thermal oxidation. The parameters are obtained a least squares fit to data available in the furnace logbooks. Information on wafer orientation and doping concentration, which is not available in the logbooks, has not been included in calculating the parameters.

Anneal Oxide Anneal Bond Boron Drive-in Gate Oxide Phosphor Drive-in
Recipe B [µm2/h] B/A [µm/h] RMSE [nm] B [µm2/h] B/A [µm/h] RMSE [nm] B [µm2/h] B/A [µm/h] RMSE [nm] B [µm2/h] B/A [µm/h] RMSE [nm] B [µm2/h] B/A [µm/h] RMSE [nm]
DRY900 0.000408 0.107 Too little data 0.0660 0.272 31 0.000390 0.154 Too little data 0.0028 0.079 4 (limited data) 0.0507 0.884 Too little data
DRY1000 - - - - - - 0.465 0.838 20 - - - 0.641 1.45 41
DRY1050 0.0111 0.526 27 - - - 0.0129 0.330 8 0.022 0.505 3 (limited data) 0.0134 0.362 6
DRY1100 0.020 0.930 10 - - - 0.0212 0.736 23 - - - 0.0313 0.553 14
WET950 - - - - - 0.0716 1.25 12 - - - 0.110 1.17 11
WET1000 0.192 1.54 44 - - 0.192 1.80 29 - - - 0.195 2.49 22
WET1050 0.487 0.965 29 0.477 0.899 Too little data 0.455 1.33 16 - - - 0.448 1.73 12
WET1100 0.580 1.43 8 - - - 0.519 1.186 3 - - - 0.403 9.05 7

Wet Oxidation on <100>

The curves below are based on measurements in our specific furnaces and give more accurate results. We will still recommend to make minimum one test run if the thickness is very important.

  • Wet oxidation
  • A1 Furnace <100>-Si Wet Oxidation
    A1 Furnace <100>-Si Wet Oxidation
  • A3 Furnace <100>-Si Wet Oxidation
    A3 Furnace <100>-Si Wet Oxidation

Dry Oxidation on <100> and <111> wafer

  • Dry oxidation
  • Dry oxide on <100> wafer. The y-axis is in Å and the x-axis is in minutes.
    Dry oxide on <100> wafer. The y-axis is in Å and the x-axis is in minutes.
  • Dry oxide on <111> wafer. The y-axis is in Å and the x-axis is in minutes.
    Dry oxide on <111> wafer. The y-axis is in Å and the x-axis is in minutes.
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