The invention relates to a method of improving a surface of a semiconductor substrate, wherein the surface at least partially includes silicon.
In semiconductor device production, it is more and more important to provide semiconductor substrates of a very high quality. Defects of semiconductor substrates can be of very different origin and may occur in the bulk material of wafers or layers or on the surface of a structure. Deficient wafers, such as wafers or layers with holes or scratches on their surface or with oxide precipitates or so-called “HF-defects”, which are present in or on a wafer and will be apparent by an HF-etch step, are mostly not suitable for further use.
To improve the surface characteristic of a defective wafer, a wafer treatment of a wafer surface such as an etching step or a chemical mechanical polishing (“CMP”) step can be used to remove or to reduce the number or the size of defects at or near the wafer surface. Typical etchants are halogen bearing compounds such as HCl, HBr, HI, HF, and others. The etchant can also be a fluorine bearing compound such as SF6, or CxFx. Moreover or in addition, it is possible to treat a defect containing wafer thermally, preferably in a hydrogen bearing environment, to smooth it and to diminish its defects. The thermal treatment can be performed in a furnace or in a tool for rapid thermal processing (“RTP”). According to another approach disclosed in U.S. Pat. No. 6,287,941 B1, a defective wafer such as a cleaved film can be subjected to a combination of etching and deposition at very high temperature using a combination of etchant and deposition gases to result in a better surface quality.
Although such methods lead, in the first instance, to a superficial improvement of the surface condition of a defective wafer by smoothing, abrasion or defect covering of the respective wafer, the known methods are mostly very laborious and the corresponding defects cannot really be repaired. Thus, there remains a need to process defective wafers to increase surface quality.