Method for producing a substrate
Substrate having a first partial substrate with a carrier layer and a second partial substrate, which is bonded to the first partial substrate. The second partial substrate has an insulator layer, which is applied on the carrier layer and has at least two regions each having a different thickness, thereby forming a stepped surface of the insulator layer, and a semiconductor layer, which is applied to the stepped surface of the insulator layer and is formed at least partially epitaxially, wherein the semiconductor layer has a planar surface which is opposite to the stepped surface of the insulator layer. Transistors are formed on the semiconductor layer.
1. A method for producing a substrate, comprising:
applying a semiconductor layer, the semiconductor layer having a region of thicker thickness and a region of thinner thickness, wherein the semiconductor layer is formed at least partly by means of selective epitaxy, wherein the step of applying the semiconductor layer comprises:
forming a thin first semiconductor partial layer on an auxiliary carrier layer;
depositing a masking layer made of an insulator material on at least one region of the thin first semiconductor partial layer; and
forming a second semiconductor partial layer on any regions of the thin first semiconductor partial layer which are not covered by the masking layer;
applying an insulator layer on the semiconductor layer, the insulator layer having a region of thicker thickness and a region of thinner thickness,
wherein the insulator layer is applied such that the region of thinner thickness of the insulator layer contacts the region of thicker thickness of the semiconductor layer, and the region of thicker thickness of the insulator layer contacts the region of thinner thickness of the semiconductor layer, such that the surface of the semiconductor layer facing away from the insulator layer is planar, and
wherein the step of applying the insulator layer comprises:
depositing a first insulator partial layer on an entire surface of the substrate; and
planarizing the first insulator partial layer;
applying a carrier layer to the insulator layer, wherein the step of applying the carrier layer comprises the steps of:
providing a carrier substrate;
applying a second insulator partial layer on the carrier substrate; and
bonding the carrier substrate and the second insulator partial layer to the planarized surface of the first insulator partial layer such that the second insulator partial layer is arranged on the first insulator partial layer, and
removing the auxiliary carrier layer.
2. The method as claimed in claim 1 , wherein the planarization of the first insulator partial layer is performed by chemical mechanical polishing.
3. The method as claimed in claim 1 , further comprising producing a layer made of porous silicon on the auxiliary carrier layer, before the step of forming the thin first semiconductor partial layer.
4. The method as claimed in claim 3 , wherein the step of removing the auxiliary carrier layer by etching comprises the step of removing the porous silicon by means of a water jet.
5. The method as claimed in claim 1 , further comprising performing an H 2 heat treatment of the substrate after the step of removing the auxiliary carrier layer.
6. The method as claimed in claim 1 , wherein the carrier layer, the auxiliary carrier layer, the thin first semiconductor partial layer, and the second semiconductor partial layer essentially comprise silicon.
7. The method as claimed in claim 1 , wherein the first insulator layer and the second insulator layer essentially comprise silicon oxide.
8. The method as claimed in claim 1 , wherein the thin first semiconductor partial layer and/or the second semiconductor partial layer are formed by epitaxy and/or selective epitaxy.