High temperature processing of silicon wafers in tube furnaces is used to grow oxide films on the wafers or to drive dopant atoms into the semiconductor substrate.
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1. Cut chips are loaded into a quartz chip holder. |
| 2. The loaded chip holder is inserted into the tube furnace where the chips are either oxidized – with dry oxygen (dry or `gate' oxide) or water-saturated oxygen (wet or `field' oxide) – or are doped by high temperature diffusion of impurity atoms into the silicon lattice. |  |
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3. In wet oxidation, oxygen is bubbled through hot water prior to passing through the tube furnace. |
| 4. A spin coater can be used to spin on a uniform thin film containing dopant atoms that will be driven into the silicon lattice in the tube furnace. |  |
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5. For impurity diffusion, dry nitrogen flows through the tube during diffusion in order to avoid oxidation during the process. |