Method and device for depositing an epitaxial layer on a substrate wafer made of semiconductor material
A method deposits an epitaxial layer on a semiconductor substrate having a wedge-shaped cross section. The substrate is arranged in a deposition apparatus to rest concentrically on a susceptor held by a supporting shaft. The supporting shaft rotates with a time period. Deposition gas is passed over the substrate between a gas inlet and outlet. Flushing gas is passed along a lower side of a preheating ring and of the susceptor. The supporting shaft is displaced with the time period along a displacement path from a position where a thinner edge of the substrate has its smallest distance from the gas inlet, to where the thinner edge has its largest distance therefrom, and back.
1 . A method for depositing an epitaxial layer on a substrate wafer comprising semiconductor material, the substrate wafer having a wedge-shaped cross section with a thinner edge and a thicker edge, as compared to each other, the method comprising:
arranging the substrate wafer and a susceptor in a deposition apparatus so that the substrate wafer rests concentrically on the susceptor, and so that the susceptor is held by a supporting shaft;
rotating the supporting shaft with a time period;
passing deposition gas over the substrate wafer in a direction from a gas inlet to a gas outlet;
passing flushing gas with a flow rate along a lower side of a preheating ring and a lower side of the susceptor; and
displacing the supporting shaft with the time period along a displacement path in a direction starting from an initial position, in which the thinner edge has its smallest distance from the gas inlet, to a final position in which the thinner edge has its largest distance from the gas inlet, and back to the initial position.
2 . The method as claimed in claim 1 , wherein a length of the displacement path from the initial position to the final position is proportional to a difference between a thicknesses at the thicker edge and a thickness at the thinner edge of the cross section.
3 . The method as claimed in claim 1 , the method further comprising:
measuring a shape of the substrate wafer before the deposition of the epitaxial layer; and
varying a speed of the displacement of the supporting shaft as a function of the shape.
4 . The method as claimed in claim 1 , the method further comprising:
measuring a shape of the substrate wafer before the deposition of the epitaxial layer; and
varying the flow rate of the flushing gas as a function of the shape.
5 . The method as claimed in claim 1 , wherein the supporting shaft is tilted toward the preheating ring.