Dry Oxidation
Parameters
This section contains the procedures utilized to grow the gate oxide and simultaneously drive the dopant further into the substrate.
Dry Oxidation Parameters
Parameter |
Temperature (C) |
Time (min) |
O2 flow (cc/min) |
N2 flow (cc/min) |
Value |
1057 |
100 |
130 |
60 |
Procedure: Furnace Preparation
- Ensure that there is enough O2pressure in the oxygen tank and N2 in the nitrogen tank for the duration of the oxidation run.
- Stabilize the lower furnace to the temperature specified in the Table above with N2flowing constantly the flowrate specified above.
- After the furnace has had ample time to stabilize, open the oxygen valve and allow the oxygen to flow at the flowrate specified in the Table above.
- Close the nitrogen valve.
Procedure: Dry Thermal Oxidation
- Load the wafers into the oxidation boat.
- Load “dummy” wafer at both ends of the boat.
- Place the boat of wafers in the open end of the lower furnace with the polished side facing forward for 5 minutes. Note that the temperature at the opening of the tube is approximately 400 °C.
- Slowly push the boat into the flat zone of the furnace tube. This “push” should take about 5 minutes.
- Start marking time and oxidize the wafers for the time specified in the Table above.
- After the appropriate length of time has elapsed slowly remove the boat. This removal should take about 5 minutes. Leave the boat at the open end of the furnace tube and allow the wafers to stabilize for about 5 minutes. Note that the temperature at the opening of the tube is approximately 400 °C.
- Remove the boat from the open end of the furnace tube and allow to cool for at least 10 minutes.
- Turn off gases, heaters and furnace.
Figure 9 illustrates the wafer after the gate oxide has been grown. Notice that the source and drain areas are now larger due to the thermal diffusion of the dopant.
Figure 9: Gate