Formation of silicon nitride by nitridation of porous silicon
OwnerRosemary L. Smith, Scott D. Collinsinventors
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Abstract
Low residual stress, stoichiometric or near stoichiometric, silicon nitride and silicon carbide films with thicknesses of one micron or greater are produced by reacting porous silicon with a nitrogen or carbon containing gas, such as ammonia or methane, at an appropriate temperature and pressure. The gas diffuses into the pores and reacts with the silicon skeletal structure. Because the initial structure is porous and the pore spaces provide strain relief during the addition reaction and subsequent volume expansion, the resultant film has relatively low residual stress. Either porous or solid films can be produced. This process provides a means to chemically stabilize porous silicon layers and their morphologies.
Claims9
A method for fabricating low residual stress insulating films in a silicon substrate comprising the steps of:
- a) forming a porous silicon layer in a silicon layer or silicon substrate,
- b) nitriding the porous silicon layer in a non-oxidizing ambient of nitrogen, ammonia, a nitrogen-containing chemical, or combinations thereof, at a temperature less than 1000.degree. C.,
- c) continuing step (b) for a time sufficient to convert the porous silicon layer to a silicon nitride layer with a thickness greater than one micron.
Dependencies are inferred from the claim text.