Abstract:
A method for manufacturing a semiconductor substrate of a first concentration type is described, which comprises at least a buried insulating cavity, comprising the following steps: forming on the semiconductor substrate a plurality of trenches, forming a surface layer on the semiconductor substrate in order to close superficially the plurality of trenches forming in the meantime at least a buried cavity in correspondence with the surface-distal end of the trenches.
Abstract:
A method for forming an interface free layer of silicon on a substrate of monocrystalline silicon is provided. According to the method, a substrate of monocrystalline silicon having a surface substantially free of oxide is provided. A silicon layer in-situ doped is deposited on the surface of the substrate in an oxygen-free environment and at a temperature below 700null C. so as to produce a monocrystalline portion of the silicon layer adjacent to the substrate and a polycrystalline portion of the silicon layer spaced apart from the substrate. The silicon layer is heated so as to grow the monocrystalline portion of the silicon layer through a part of the polycrystalline portion of the silicon layer. Also provided is a method for manufacturing a bipolar transistor.
Abstract:
A method of controlling the quantity and uniformity of distribution of bonded oxygen atoms at the interface between the polysilicon and the monocrystalline silicon includes carrying out, after having loaded the wafer inside the heated chamber of the reactor and evacuated the chamber of the LPCVD reactor under nitrogen atmosphere, a treatment of the wafer with hydrogen at a temperature generally between 500 and 1200null C. and at a vacuum generally between 0.1 Pa and 60000 Pa. The treatment is performed at a time generally between 0.1 and 120 minutes, to remove any and all the oxygen that may have combined with the silicon on the surface of the monocrystalline silicon during the loading inside the heated chamber of the reactor even if it is done under a nitrogen flux. After such a hydrogen treatment, another treatment is carried out substantially under the same vacuum conditions and at a temperature generally between 700 and 1000null C. with nitrogen protoxide (N2O) for a time generally between 0.1 and 120 minutes.