Page buffer for memory devices
A variety of applications can include apparatus having a memory device structured with a circuit under array (CuA) architecture. A page buffer region in the CuA can be formed with a periphery region that is horizontally adjacent to the page buffer region. Contacts to gates for transistors in the page buffer region can be formed to land only on these gates, separating and electrically isolating the contacts and associated gates from each other in the page buffer region. Contacts to gates for transistors in the periphery region can be formed to land on conductive regions disposed on gates for transistors in the periphery region.
1 . A method of forming a memory device, the method comprising:
processing a periphery region and a page buffer region for the memory device, the periphery region horizontally adjacent to the page buffer region, with each of the periphery region and the page buffer region having multiple gate regions separated by isolation regions and having a conductive region continuously disposed on and contacting the multiple gate regions and the isolation regions in the periphery region and the page buffer region;
removing the conductive region completely from contacting the multiple gate regions and the isolation regions in the page buffer region, electrically isolating the gate regions from each other in the page buffer region; and
completing, after electrically isolating the gate regions from each other in the page buffer region, formation of transistors corresponding to the gate regions in the periphery region and in the page buffer region.
2 . The method of claim 1 , wherein the periphery region and the page buffer region are disposed in a region for circuits below a memory array of the memory device.
3 . The method of claim 1 , wherein the conductive region includes a tungsten silicide or tungsten.
4 . The method of claim 1 , wherein the multiple gate regions of the periphery region and the page buffer region include polysilicon.
5 . The method of claim 1 , wherein removing the conductive region includes dry etching the conductive region from the page buffer region.
6 . The method of claim 1 , wherein the method includes forming metal contacts directly to polysilicon gate regions in the page buffer region after electrically isolating the gate regions from each other in the page buffer region and make gate contacts in the periphery region using tungsten.
7 . A method of forming a memory device, the method comprising:
forming a capping dielectric on a conductive region, the conductive region continuously disposed on and contacting multiple gate regions and isolation regions in a periphery region and in a page buffer region for the memory device, with the multiple gate regions separated from each other by the isolation regions, the periphery region horizontally adjacent to the page buffer region;
forming a masking region on the capping dielectric;
removing the capping dielectric and the conductive region completely from contacting the multiple gate regions and the isolation regions in the page buffer region, electrically isolating the gate regions from each other in the page buffer region, and maintaining the capping dielectric on the conductive region in the periphery region; and
completing, after electrically isolating the gate regions from each other in the page buffer region, formation of transistors corresponding to the gate regions in the periphery region and the page buffer region.
8 . The method of claim 7 , wherein the method includes, prior to forming the capping dielectric:
forming the multiple gate regions and the isolation regions in the periphery region and in the page buffer region; and
blanket depositing the conductive region on the periphery region and on the page buffer region.
9 . The method of claim 7 , wherein the method includes, prior to completing formation of the transistors:
forming an isolation dielectric on the electrically isolated gate regions in the page buffer region and on the maintained capping dielectric on the conductive region in the periphery region; and
subjecting the isolation dielectric to a chemical-mechanical planarization such that a first top level of the isolation dielectric in the periphery region is at a top level of the isolation dielectric in the page buffer region.
10 . The method of claim 9 , wherein forming the isolation dielectric includes forming tetraethyl orthosilicate.
11 . The method of claim 7 , wherein the periphery region and the page buffer region are disposed in a region for circuits below a memory array of the memory device.
12 . The method of claim 7 , wherein the conductive region includes a tungsten silicide or tungsten.
13 . The method of claim 7 , wherein forming the capping dielectric includes depositing an oxide.
14 . The method of claim 7 , wherein forming the masking region is part of performing a photolithographic process.
15 . The method of claim 7 , wherein removing the conductive region and capping dielectric includes etching material of the masking region above the capping dielectric on the conductive region in the periphery region and etching the capping dielectric and the conductive region from the page buffer region.
16 . The method of claim 7 , wherein the method includes:
forming metal contacts directly to the gate regions in the page buffer region; and
coupling the metal contacts to provide vertical electrical communication paths to one or more circuits for a memory array of the memory device.