Method for fabricating a capacitor
View Patent ↗In a method for fabricating a capacitor that includes an electrode structure ( 80 ), an auxiliary layer ( 40 ) is formed over a substrate ( 10 ). A recess ( 60 ), which determines the shape of the electrode structure ( 80 ), is etched into the auxiliary layer ( 40 ), and the electrode structure of the capacitor is formed in the recess. As an example, the auxiliary layer can be a semiconductor layer ( 40 ).
1. A method for fabricating a capacitor, the method comprising:
forming a semiconductor layer over a substrate;
etching a cup shaped recess into the semiconductor layer;
forming an interior cup shaped electrode for a capacitor in the recess, said interior cup shaped electrode including a cup inner wall and a cup outer wall; and
forming an exterior electrode along both the inner wall and outer wall of the cup, wherein a portion of the exterior electrode along the cup inner wall and a portion of the exterior electrode along the cup outer wall are produced in different process steps.
2. The method according to claim 1 , wherein the semiconductor layer is a sacrificial layer that is partially or completely removed as part of the fabrication of the capacitor.
3. The method according to claim 2 , wherein the semiconductor layer is completely or partially removed using an etchant containing hydrogen peroxide or using pure hydrogen peroxide.
4. The method according to claim 1 , wherein the exterior electrode is separated from the interior electrode by an insulator layer.
5. The method according to claim 1 , wherein the portion of the exterior electrode along the cup inner wall is produced before the portion of the exterior electrode along the cup outer wall.
6. The method according to claim 1 , wherein the portion of the exterior electrode along the cup inner wall is produced after the portion of the exterior electrode along the cup outer wall.
7. The method according to claim 1 , wherein the portion of the exterior electrode along the cup inner wall and the portion of the exterior electrode along the cup outer wall are connected by a conductive capping layer.
8. The method according to claim 7 , wherein the conductive capping layer comprises a doped silicon layer.
9. The method according to claim 1 , wherein the exterior electrode and/or the interior electrode are formed from TiN or a TiN-containing material.
10. The method according to claim 1 , wherein the interior electrode is formed from doped silicon.
11. The method according to claim 1 , wherein the portion of the exterior electrode along the cup inner wall or the portion of the exterior electrode along the cup outer wall, or both, is produced from doped silicon.
12. The method according to claim 1 , wherein the capacitor is coupled to a terminal of a transistor.
13. The method according to claim 12 , further comprising producing a DRAM memory element using the capacitor.
14. The method according to claim 13 , further comprising producing a capacitor-over-bitline element using the capacitor.
15. The method according to claim 1 , wherein the capacitor is integrated in a semiconductor structure.
16. The method according to claim 1 , wherein the interior electrode is always mechanically supported throughout the entire method.
17. The method according to claim 16 , wherein the interior electrode is mechanically supported by the semiconductor layer, which remains along the outer wall.
18. The method according to claim 1 , further comprising:
after forming an interior cup shaped electrode, depositing a mechanical support filling along the cup inner wall; and
before forming an exterior electrode along the inner wall of the cup, removing the mechanical support filling.
19. The method according to claim 1 , wherein the semiconductor layer comprises a SiGe layer.
20. The method according to claim 19 , wherein the recess is etched into the SiGe layer using an etchant containing hydrogen peroxide or using pure hydrogen peroxide.
21. The method according to claim 19 , wherein the SiGe layer has a Ge content of at least 40%.