Multi-level contact to a 3D memory array and method of making

摘要

A method of making multi-level contacts. The method includes providing an in-process multilevel device including at least one device region and at least one contact region. The contact region includes a plurality of electrically conductive layers configured in a step pattern. The method also includes forming a conformal etch stop layer over the plurality of electrically conductive layers, forming a first electrically insulating layer over the etch stop layer, forming a conformal sacrificial layer over the first electrically insulating layer and forming a second electrically insulating layer over the sacrificial layer. The method also includes etching a plurality of contact openings through the etch stop layer, the first electrically insulating layer, the sacrificial layer and the second electrically insulating layer in the contact region to the plurality of electrically conductive layers.

主权项

1. A multilevel device, comprising:
at least one device region and at least one contact region having a plurality of stacked electrically conductive layers, wherein the electrically conductive layers form a stepped pattern in the contact region; a conformal etch stop layer located over the electrically conductive layers; a first electrically insulating layer located over the etch stop layer; a conformal sacrificial layer located over the first electrically insulating layer; a second electrically insulating layer located over the sacrificial layer; a plurality of contact openings extending through the etch stop layer, the first electrically insulating layer, the sacrificial layer and the second electrically insulating layer in the contact region to the plurality of electrically conductive layers; and a plurality of electrically conductive contacts, wherein each respective one of the plurality of electrically conductive contacts is located in a respective one of the plurality of contact openings, and each electrically conductive contacts is in electrical contact with a respective one of the plurality of electrically conductive layers; wherein: the plurality of electrically conductive layers comprise at least a first conductive layer in a first device level located over a substrate and a second conductive layer in a second device level located higher than the first device level over the substrate; the first conductive layer comprises a first portion which laterally extends past the second conductive layer to form at least a portion of the step pattern; the plurality of contact openings comprises a first contact opening which extends to the first portion of the first conductive layer and a second contact opening which extends to an upper surface of the second conductive layer; a first electrically conductive contact of the plurality of electrically conductive contacts is located in the first contact opening; a second electrically conductive contact of the plurality of electrically conductive contacts is located in the second contact opening; in the first electrically conductive contact extends deeper than the second electrically conductive contact; each of the conformal etch stop layer, the first electrically insulating layer and the sacrificial layer has a substantially uniform thickness and each is arranged in the step pattern over the plurality of electrically conductive layers in the contact region; the second electrically insulating layer has a variable thickness and a substantially planar upper surface; and the second electrically insulating layer is thicker over the first portion of the first conductive layer than over the second conductive layer.