Specific Process Knowledge/Thermal Process/Oxidation/Breakdown voltage measurements

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Breakdown voltage measurements

In order to evaluate the quality of the wet and dry oxide layers that can be grown in the A1 Boron Drive-in and Pre-dep and the A3 Phosphorus Pre-dep furnaces, some breakdown voltage measurement have been made. The breakdown voltage is the maximum voltage that can be applied to an insulating material like silicon oxide, before it starts to conduct.

The breakdown voltage measurements were performed using a automated measure setup at DTU Health Tech. This setup automatically measures the breakdown voltage in a pattern over each wafer. Each field in the pattern has a gold contact. The measurements are done by applying an increasing reverse voltage to each field in the pattern via a probe, until certain current is reached that indicates a breakdown, see the drawing.



Some fields in pattern are excluded from the results. The reason for this is either that the contact between the probe and the gold contact has not been been sufficient, or the probe has become dirty during the measurement.

The absolute breakdown voltage has been measured, and the relative breakdown voltage has been calculated. The relative breakdown voltage is the breakdown voltage per nm of the oxide layer.

The measurements were made in November 2021 with help from Kitty Steenberg and Rune Sixten Grass from DTU Health Tech.


Procedure

The procedure for the breakdown voltage measurements is the following:

  • RCA clean new Si wafers (double side polished wafers from the box TP473)
  • Grow wet or dry oxide of both sides of the wafers in the A1 or A3 furnace
  • Spin resist on the front side of the wafers
  • Remove the oxide on the back side of the wafers using BHF in Oxide etch 2
  • Remove the resist on the front side of the wafers using plasma ashing
  • Deposit 10 nm Ti and 100 nm Au through a shadow mask on the front side of the wafers using e-beam deposition in the Temescal
  • Measure the break-down voltage


Breakdown voltage results for the A1 Boron Drive-in and Pre-dep furnace

Breakdown voltage measurements for dry oxide

Oxidation parameters:

  • Temperature: 1050 C
  • Oxidation time: 1 h 40 min
  • Annealing time: 20 min

Oxide thickness: ~100 nm

  • A1 furnace, dry oxidation

  • Absolute breakdown voltage

  • Relative breakdown voltage

Breakdown voltage measurements for wet oxide

Oxidation parameters:

  • Temperature: 1050 C
  • Oxidation time: 30 min
  • Annealing time: 20 min

Oxide thickness: ~300 nm

  • A1 furnace, wet oxidation

  • Absolute breakdown voltage

  • Relative breakdown voltage

The measurements were made in November 2021 with help from Kitty Steenberg and Rune Sixten Grass from DTU Health Tech.

Breakdown voltage results for the A2 Gate Oxide furnace

Breakdown voltage measurements for dry oxide

Oxidation parameters:

  • Temperature: 1050 C
  • Oxidation time: 1 h 40 min
  • Annealing time: 20 min

Oxide thickness: ~150 nm

  • A2 furnace, dry oxidation

  • Absolute breakdown voltage

  • Relative breakdown voltage

The measurements were made in February 2022 with help from Kitty Steenberg and Rune Sixten Grass from DTU Health Tech.

Breakdown voltage results for the A3 Phosphorus Drive-in furnace

Right before the breakdown voltage measurements were made, all quartz parts in the furnace were changed.

Breakdown voltage measurements for dry oxide

Oxidation parameters:

  • Temperature: 1050 C
  • Oxidation time: 1 h 40 min
  • Annealing time: 20 min

Oxide thickness: ~110 nm

  • A3 furnace, dry oxidation

  • Absolute breakdown voltage

  • Relative breakdown voltage

Breakdown voltage measurements for wet oxide

Oxidation parameters:

  • Temperature: 1050 C
  • Oxidation time: 30 min
  • Annealing time: 20 min

Oxide thickness: ~320 nm

  • A3 furnace, wet oxidation

  • Absolute breakdown voltage

  • Relative breakdown voltage

The measurements were made in November 2021 with help from Kitty Steenberg and Rune Sixten Grass from DTU Health Tech.

Breakdown voltage results for Oxidation (8") furnace (E1)

Breakdown voltage measurements for dry oxide

Oxidation parameters:

  • Temperature: 1050 C
  • Oxidation time: 1 h 40 min
  • Annealing time: 20 min

Oxide thickness: ~117 nm

  • E1 furnace, dry oxidation

  • Absolute breakdown voltage

  • Relative breakdown voltage

The measurements were made in February 2022 with help from Kitty Steenberg and Rune Sixten Grass from DTU Health Tech.

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