Denuding a semiconductor substrate
AssigneeMotorola, Inc.
InventorsYoung Limb, Philip J. Tobin
Life of this patent
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Abstract
A semiconductor substrate is denuded using a reducing gas mixture including carbon monoxide and carbon dioxide. Use of the reducing gas mixture allows very low oxygen partial pressure to be achieved in a furnace tube during the step of denuding. Oxygen partial pressure lower than 1E-9 atmosphere may be achieved by adjusting the relative ratio of carbon monoxide and carbon dioxide. Precipitates are grown after forming nucleating sites. Both CZ and FZ substrates may use the process, and the process can be used with silicon, germanium, or other semiconductor materials.
Claims18
A process for forming a denuded zone within a semiconductor substrate comprising the steps of:
- providing the semiconductor substrate having a primary surface and an oxygen concentration in a region adjacent to the primary surface;
- heating the substrate to a first elevated temperature in a reducing ambient that includes carbon-containing molecules to lower the oxygen concentration within the region.
A process for forming a denuded zone within a silicon substrate comprising the steps of:
- providing the silicon substrate having a primary surface and an oxygen concentration in a region adjacent to the primary surface that is about 5-50 parts per million;
- heating the substrate to a first elevated temperature that is at least 1000 degrees Celsius for about 1-4 hours in a reducing ambient that includes carbon monoxide and carbon dioxide;
- lowering the temperature of the substrate to a second elevated temperature that is about 450-850 degrees Celsius;
- and
- maintaining the substrate at the second elevated temperature for a time to form nucleating sites for oxygen precipitates within the bulk of the substrate, wherein the region lies between the bulk and the primary surface.
Dependencies are inferred from the claim text.