Method for forming a cavity and a component having a cavity

1. A method for forming a cavity in a silicon substrate, comprising:

providing the silicon substrate, a surface of the silicon substrate having a tilting angle relative to a first plane of the silicon substrate, and the first plane being a {111} plane of the silicon substrate;

situating an etching mask on the surface of the silicon substrate, the etching mask having a mask opening having a first transverse edge and a second transverse edge parallel to the first transverse edge, the first transverse edge being situated in the first plane of the silicon substrate, the etching mask having a first retarding structure that protrudes into the mask opening, the etching mask having a first etching projection region, and all further edges of the mask opening outside the first etching projection region being situated parallel to {111} planes of the silicon substrate; and

anisotropically etching the silicon substrate during a defined etching duration, an etching rate in the <111> directions of the silicon substrate being lower than in other spatial directions, the first retarding structure being undercut going out from the first etching projection region in a first undercut direction, the first undercut direction being oriented parallel to the first transverse edge and the second transverse edge of the mask opening, the etching duration being defined such that through the anisotropic etching, a cavity forms in the silicon substrate hat has an opening on the surface of the silicon substrate, the opening of the cavity being limited at two sides by the first transverse edge and the second transverse edge of the mask opening, and at a further side by a first longitudinal edge, perpendicular to the first and to the second transverse edge, that is produced by the undercutting of the first retarding structure, and the etching duration moreover being defined such that after elapsing of the etching duration, the first plane of the silicon substrate is exposed and forms a floor surface of the cavity.

2. The method as recited in claim 1 , wherein the etching mask has a second retarding structure that protrudes into the mask opening, the etching mask having a second etching projection region, the second retarding structure being undercut by the anisotropic etching of the silicon substrate, going out from the second etching projection region, in a second undercut direction opposite the first undercut direction, in such a way that after the elapsing of the etching duration a second longitudinal edge limiting the opening of the cavity is formed that is situated parallel to the first longitudinal edge.

3. The method as recited in claim 1 , wherein the first etching projection region has an etched edge that is not situated parallel to a {111} plane of the silicon substrate.

4. The method as recited in claim 1 , wherein the first retarding structure has a triangular base structure, the first longitudinal edge being fashioned at a first side of the triangular base structure, and a second side and a third side of the triangular base structure being situated parallel to {111} planes of the silicon substrate.

5. The method as recited in claim 4 , wherein the first retarding structure has a first delaying structure that is situated at a first corner, situated opposite the first side, of the triangular base structure.

6. The method as recited in claim 5 , wherein the first delaying structure connects the first corner of the triangular base structure to at least one of the first transverse edge and the second transverse edge.

7. The method as recited in claim 1 , wherein the etching mask has at least one reinforcing structure that connects the first retarding structure to at least one of the first transverse edge and the second transverse edge.

8. The method as recited in claim 1 , wherein the etching mask has a third etching projection region, the first retarding structure being undercut, going out from the first etching projection region and the third etching projection region, in such a way that, upon elapsing of the etching duration, the first longitudinal edge, limiting the opening of the cavity, is formed.

9. The method as recited in claim 8 , wherein the first retarding structure has a first segment having a first oblong region and a first pointed region, and having a second segment having a second oblong region and a second pointed region, a first point of the first pointed region forming the first etching projection region, and a second point of the second pointed region forming the third etching projection region, a first side of the first oblong region being situated at the first pointed region and a first side of the second oblong region being situated at the second pointed region, and the first longitudinal edge being fashioned at a second side of the first oblong region and at a second side of the second oblong region.

10. The method as recited in claim 1 , further comprising:

creating a through-opening between the floor surface of the cavity and a rear side, situated opposite the surface, of the silicon substrate.

11. The method as recited in claim 10 , further comprising:

forming a further cavity on the rear side of the silicon substrate, the through-opening being placed between the floor surface of the cavity and a floor surface of the further cavity.

12. The method as recited in claim 11 , wherein the creating of the through-opening includes:

forming a first trench that extends from the floor surface of the cavity into the silicon substrate in the direction of the further cavity;

forming a second trench that extends from the floor surface of the further cavity into the silicon substrate in the direction of the cavity; and

separating a part of the silicon substrate that is situated between the first trench and the second trench.

13. The method as recited in claim 12 , further comprising:

situating a small window plate in the cavity in such a way that the small window plate covers the through-opening and lies on an edge surface, situated in the floor surface of the cavity, that surrounds the through-opening.