Method for producing ferroelectric capacitors and integrated semiconductor memory chips
View Patent ↗The invention relates to a method for producing ferroelectric capacitors that are structured using the stack principle and that are used in integrated semiconductor memory chips. The individual capacitor modules have an oxygen barrier between a lower capacitor electrode and an electrically conductive plug. At a site where it is not covered by the corresponding oxygen barrier, an unstructured adhesive layer is oxidized by the oxygen arising during the tempering process of the ferroelectric and forms insulating segments at the site in such a way that the lower capacitor electrodes of the ferroelectric capacitors are electrically insulated from one another. This makes it possible to dispense with structuring the adhesive layer. Furthermore, the layer serves as a getter of oxygen and inhibits the diffusion of oxygen to the plug.
1. A method for producing ferroelectric capacitors in an integrated semiconductor memory chip, the method which comprises:
constructing the ferroelectric capacitors in accordance with a stacked principle;
forming an oxygen barrier between a metallic bottom capacitor electrode of a ferroelectric capacitor and a conductive plug connecting the bottom capacitor electrode to a semiconductor electrode lying below the ferroelectric capacitor or to a metallization track;
configuring an unpatterned adhesion layer made of a conductive material in a region having the ferroelectric capacitors and configuring the adhesion layer between the plug and the oxygen barrier; and
performing a heat treatment step to oxidize sections of the adhesion layer that are not covered by the oxygen barrier and to thereby convert the sections of the adhesion layer into an insulating layer.
2. The production method according to claim 1 , wherein the heat treatment step is performed for depositing a ferroelectric of the ferroelectric capacitors.
3. The production method according to claim 1 , wherein the adhesion layer contains Ta.
4. The production method according to claim 1 , which comprises making the conductive plug from polysilicon or tungsten.
5. The production method according to claim 1 , wherein the sections of the adhesion layer that are oxidized also extend under edge regions of the oxygen barrier.
6. The production method according to claim 1 , wherein the ferroelectric capacitors form an operative part of the integrated semiconductor memory chip.