Nxp B.v.

Claire Ravit

Philippe Meunier-Beillard

Jurriaan Schmitz

Rita Victoire Theodosie Rooyackers

The invention relates to a method of manufacturing a semiconductor strained layer and to a method of manufacturing a semiconductor device () in which a semiconductor body () of silicon is provided, at a surface thereof, with a first semiconductor layer () having a lattice of a mixed crystal of silicon and germanium and a thickness such that the lattice is substantially relaxed, and on top of the first semiconductor layer () a second semiconductor layer () is provided comprising strained silicon, in which layer () a part of the semiconductor device () is formed, and wherein measures are taken to avoid reduction of the effective thickness of the strained silicon layer () during subsequent processing needed to form the semiconductor device (), said measures comprising the use of a third layer () having a lattice of a mixed crystal of silicon and germanium. According to the invention, the third layer () is thin and positioned within the second layer () close to the interface between the first and second semiconductor layers (). In this way the resulting thickness of the strained silicon layer (), after subsequent formation of the MOSFET, can be increased, resulting in a MOSFET with better high-frequency properties. The invention also comprises a device obtained with a method according to the invention and a semiconductor substrate structure suitable for use in such a method.

Method of manufacturing a strained semiconductor layer, method of manufacturing a semiconductor device and semiconductor substrate suitable for use in such a method including having a thin delta profile layer of germanium close to the bottom of the strained layer

A method of manufacturing a semiconductor device comprising a silicon body () having a surface () provided with field isolation regions () enclosing active regions (). In this method, on the surface of the silicon body there is formed an auxiliary layer () of a material on which, during an oxidation treatment, a thicker layer of silicon oxide is formed than on the silicon of the silicon body. Here, an auxiliary layer comprising silicon and germanium is formed on the surface, said auxiliary layer preferably being a layer of SixGe1&#x2212;x&#x2212;yCy, where 0.70&#x3c;x&#x3c;0.95 and y&#x3c;0.05. Next, at the location of the field isolation regions to be formed, windows () are formed in the auxiliary layer and trenches () are formed in the silicon body. Next, on the walls () of the trenches, a silicon oxide layer () is provided and on the walls () of the windows a silicon oxide layer () is provided, both being formed by an oxidation treatment. The auxiliary layer is not oxidized throughout its thickness. After the oxidation treatment, a layer of insulating material () is deposited which fills the trenches and windows completely. Then, successively, a planarization treatment is carried out until the non-oxidized part of the auxiliary layer () is exposed, and the exposed part of the auxiliary layer is removed. Thus, field isolation regions () are formed having an edge () extending above the active regions ().

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Leuven, Belgium

Claire Ravit