Semiconductor device and method of processing the same
View Patent ↗Provided is a semiconductor wafer. In the semiconductor wafer, formation and etching of an n type epitaxial layer and formation and etching of a p type epitaxial layer are alternately performed for at least three times, so that all semiconductor layers are formed of epitaxial layers on a semiconductor substrate. Thereby, the respective semiconductor layers can be formed to have reduced widths. Thus, if a required breakdown voltage is the same, dopant concentrations of the respective semiconductor layers can be increased and a resistance value of the wafer can be reduced. In addition, a space portion remaining in the end is buried with an insulating layer, so that a defect can be avoided in a junction surface of the epitaxial layers.
1. A semiconductor wafer comprising:
a semiconductor substrate;
a plurality of first epitaxial semiconductor layers of a first general conductivity type grown from the semiconductor substrate, the first epitaxial semiconductor layers standing on the semiconductor at a predetermined interval;
a plurality of second epitaxial semiconductor layers of a second general conductivity type grown from corresponding first epitaxial semiconductor layers, the second epitaxial semiconductor layers standing on the semiconductor substrate and being in contact with the corresponding first epitaxial semiconductor layers;
a plurality of third epitaxial semiconductor layers of the first general conductivity type grown from corresponding second epitaxial semiconductor layers, the third epitaxial semiconductor layers standing on the semiconductor substrate and being in contact with the corresponding second epitaxial semiconductor layers; and
a plurality of insulating layers standing on the semiconductor substrate so that a third epitaxial semiconductor layer, a second epitaxial semiconductor layer, a first epitaxial semiconductor layer, another second epitaxial semiconductor layer and another third epitaxial semiconductor layer are disposed in this order between two insulating layers with no other insulating layer being disposed between the two insulating layers,
wherein epitaxial semiconductor layers in contact with the insulating layers are of the same general conductivity type.
2. The semiconductor wafer according to claim 1 , further comprising a plurality of fourth epitaxial semiconductor layers of the second general conductivity type grown from corresponding third epitaxial semiconductor layers, the fourth epitaxial semiconductor layers standing on the semiconductor substrate and being in contact with the corresponding third epitaxial semiconductor layers.
3. The semiconductor wafer according to claim 2 , wherein impurity concentration profiles of the first to fourth epitaxial semiconductor layers are uniform in a direction normal to the semiconductor substrate.
4. A method for processing a semiconductor wafer, comprising:
providing a semiconductor wafer of a first general conductivity type;
growing a first epitaxial semiconductor layer of the first general conductivity type from the semiconductor wafer;
etching the first epitaxial semiconductor layer to form a plurality of trenches;
growing a second epitaxial semiconductor layer of a second general conductivity type from the etched first epitaxial semiconductor layer so as to leave a void in each trench;
etching the second epitaxial semiconductor layer so as to expose a top surface of the first epitaxial semiconductor layer;
growing a third epitaxial semiconductor layer of the first general conductivity type from the exposed top surface of the first epitaxial semiconductor layer and the etched second epitaxial semiconductor layer in the trenches so that the voids are filled at least partially with the third epitaxial semiconductor layer;
etching the third epitaxial semiconductor layer so as to expose the top surface of the first epitaxial semiconductor layer and a top surface of the second epitaxial semiconductor layer;
forming an insulating layer so as to cover the exposed top surfaces of the first and second epitaxial semiconductor layers and the etched third epitaxial semiconductor layer in the trenches so that the partially filled voids are filled with the insulating layer; and
etching the insulating layer so as to expose the top surfaces of the first and second epitaxial semiconductor layers and a top surface of the third epitaxial semiconductor layer.
5. The method of claim 4 , wherein the formation of the trenches comprises removing a damaged layer by thermal oxidation of the first epitaxial semiconductor layer.
6. The method of claim 4 , further comprising growing, prior to the formation of the insulating layer, a fourth epitaxial semiconductor layer of the second general conductivity type from the exposed top surfaces of the first, second and third epitaxial semiconductor layers and the etched third epitaxial semiconductor layer in the voids, and etching the fourth epitaxial semiconductor layer so as to expose the top surfaces of the first, second and third epitaxial semiconductor layers and a top surface of the fourth epitaxial semiconductor layer.
7. The method of claim 6 , wherein impurity concentration profiles of the first to fourth epitaxial semiconductor layers are uniform in a direction normal to the semiconductor wafer.