3D Memory Terrace Contact Structure for Etch Depth Control
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Solution Overview
Problem
The existing semiconductor memory devices face challenges in manufacturability, particularly in controlling the depth of contact holes and preventing short-circuiting, due to the lack of effective stopper structures and material compatibility issues during the manufacturing process.
Innovation Solution
The semiconductor memory device incorporates a first metal layer disposed above the terrace portion of the conductive layers, with a conductive portion penetrating the metal layer to connect to the terrace and an insulating portion between the metal layer and the conductive portion, enhancing control over contact hole depth and preventing short-circuiting by using a metal layer as a stopper and ensuring insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a contact hole is formed to connect to the terrace portion of the stacked body, then electrical connection is achieved, but control over contact hole depth becomes difficult and short-circuiting may occur
Solution Approach 1:
A metal layer is formed in advance on the terrace portion of the stacked body before contact hole formation. This preliminary metal layer serves as a stopper that prevents over-etching during contact hole fabrication, ensuring precise depth control and preventing short-circuiting between adjacent contacts.
Solution Approach 2:
The metal layer acts as an intermediary stopper structure between the etching process and the terrace portion of the stacked body. It provides a physical barrier that mediates the etching depth, allowing precise control without directly involving the terrace structure in the contact hole formation process.
2Adaptability or versatility
If the stacked body has a stepped portion with word lines of different lengths, then device functionality is achieved, but manufacturability is reduced due to lack of effective stopper structures
Solution Approach 1:
The metal layer is deposited in advance on the terrace portion created by the stepped word lines. This preliminary action provides a uniform stopper surface that simplifies subsequent contact hole formation, making the manufacturing process easier despite the complex stepped structure required for device functionality.
Data Source
AI summary
A semiconductor memory device includes a stacked body, a first metal layer, and a first columnar body. The stacked body includes a plurality of gate electrode layers and a plurality of insulating layers. The plurality of gate electrode layers include a first gate electrode layer, and a second gate electrode layer having a length in a second direction intersecting a first direction that is shorter than that of the first gate electrode layer. The first metal layer is disposed at least on a first side with respect to a terrace portion of the first gate electrode layer. The first columnar body is disposed on the first side with respect to the terrace portion of the first gate electrode layer. The first columnar body includes a conductive portion extending in the first direction and penetrating the first metal layer to be connected to the terrace portion of the first gate electrode layer, and an insulator disposed at least between the first metal layer and the conductive portion.