| CPC H01L 21/02639 (2013.01) [H01L 21/02532 (2013.01); H10D 84/0167 (2025.01); H10D 84/038 (2025.01)] | 15 Claims |
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1. A method for epitaxial growth in an FDSOI (fully depleted semiconductor on insulator), comprising:
step 1, providing an FDSOI substrate structure, wherein the FDSOI substrate structure comprises a hybrid region, wherein the hybrid region comprises a semiconductor body layer, a dielectric buried layer, and a semiconductor top layer; forming the dielectric buried layer on a surface of the semiconductor body layer, forming the semiconductor top layer on a surface of the dielectric buried layer; and forming a hard mask layer on a surface of the semiconductor top layer;
step 2, forming a trench in the hybrid region by removing portions of the hard mask layer, the semiconductor top layer, and the dielectric buried layer from a trench area, wherein a bottom surface of the trench is flush with or below a top surface of the semiconductor body layer, wherein the bottom surface of the trench exposes a portion of a surface of the semiconductor body layer, wherein the portion of the surface of the semiconductor body layer exposed by the bottom surface of the trench is a second top surface of the semiconductor body layer; wherein a side face of the trench exposes a side face of the hard mask layer, a side face of the semiconductor top layer, a side face of the dielectric buried layer, and a side face of the semiconductor body layer that are within a depth range of the trench;
wherein the second top surface of the semiconductor body layer comprises a first crystalline face of the semiconductor body layer, and wherein a side face of the semiconductor top layer comprises a second crystalline face of the semiconductor top layer;
step 3, performing a first epitaxial growth, wherein the first epitaxial growth is isotropic epitaxial growth, wherein the first crystalline face and the second crystalline face have a same growth rate;
forming a first semiconductor epitaxial sublayer on the second top surface of the semiconductor body layer, wherein a top surface of the first semiconductor epitaxial sublayer is located in a place between a top surface and a bottom surface of the dielectric buried layer; and
wherein the first epitaxial growth forms a second semiconductor epitaxial sublayer on the side face of the semiconductor top layer during a same period as the first epitaxial growth occurs, wherein the second semiconductor epitaxial sublayer comprises a lateral protruding structure on the side face of the semiconductor top layer; and
step 4, performing a second epitaxial growth, wherein the second epitaxial growth is an anisotropic epitaxial growth having a growth rate of the first crystalline face, wherein the growth rate of the first crystalline face is greater than a growth rate of the second crystalline face;
wherein the second epitaxial growth forms a third semiconductor epitaxial sublayer on the top surface of the first semiconductor epitaxial sublayer, wherein a top surface of the third semiconductor epitaxial sublayer is flush with a top surface of the semiconductor top layer; and
wherein the third semiconductor epitaxial sublayer comprises a chamfered recess at the side face of the semiconductor top layer, as a result of the growth rate of the first crystalline face being faster than the growth rate of the second crystalline face;
and
stacking the first semiconductor epitaxial sublayer, the second semiconductor epitaxial sublayer, and the third semiconductor epitaxial sublayer together to form a semiconductor epitaxial layer, wherein the lateral protruding structure and the chamfered recess overlap on the side face of the semiconductor top layer, such that the semiconductor epitaxial layer has a flat surface near a side surface of the semiconductor top layer.
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