Contact structure and method of forming the same

Abstract

Aspects of the disclosure provide a semiconductor device. The semiconductor device includes a memory stack of gate layers and insulating layers, a landing structure and a contact structure. The gate layers and the insulating layers are stacked alternatingly, and form stair steps in a staircase region. The landing structure is disposed on a first gate layer of a first stair step of the stair steps in the staircase region. The landing structure includes an upper structure and an isolation stack between the upper structure and the first gate layer. The upper structure is etch-selective to a contact isolation layer that covers the staircase region. The contact structure extends through the contact isolation layer and the landing structure and is connected with the first gate layer of the first stair step.