Semiconductor Memory Device Source Line Contact Structure
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Solution Overview
Problem
Reliably connecting a source line and a source line contact in a three-dimensional nonvolatile memory device is challenging due to the difficulty in maintaining effective electrical contact across the stacked structure.
Innovation Solution
The semiconductor memory device incorporates a stacked body with pillars and contacts designed to extend in specific directions, featuring a conductive layer connected to the side surface of the source line, and a contact structure with varying widths and shapes to ensure reliable electrical connection, including a conductive layer connected to the side surface of the conductive layer in the depth region, facilitating connection to the upper layer wiring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a source line contact penetrates the stacked body to connect to the source line, then electrical connection is established, but reliable connection becomes difficult to maintain
Solution Approach 1:
The contact structure is divided into multiple segments: a first contact portion extending from the upper surface to a first depth, and a second contact portion extending from the first depth to the lower surface. This segmentation allows each portion to be optimized independently for its specific function, improving overall connection reliability while managing structural complexity.
Solution Approach 2:
The contact structure transitions from a simple vertical penetration to a multi-dimensional configuration with varying widths at different depths. The first contact portion has a first width at the upper surface and a second width at the first depth, creating a tapered or stepped structure that enhances electrical contact and mechanical stability in the depth dimension.
2Reliability
If the contact structure extends deeply into the stacked body, then connection to the source line is achieved, but manufacturing precision becomes more difficult
Solution Approach 1:
The contact structure is designed with predetermined width variations at specific depths before final formation. The first contact portion is configured with a first width at the upper surface and a second width at the first depth, allowing preliminary positioning and alignment that simplifies the subsequent manufacturing process and improves precision.
Solution Approach 2:
Different portions of the contact structure have different widths optimized for their specific locations: the first contact portion has varying widths (first width at upper surface, second width at first depth) for optimal electrical contact, while the second contact portion has a third width at the lower surface for stable connection to the source line. This local optimization improves manufacturing precision by addressing specific requirements at each depth.
Data Source
AI summary
According to one embodiment, a semiconductor memory device includes a first conductive layer, and a first structure that extends in a first direction orthogonal to a stacking direction of a stacked body and the stacking direction, and reaches a position deeper than an upper surface of the first conductive layer. The first structure has a first width at a bottom of the stacked body, and a second width narrower than the first width, in a first depth region from a position of the upper surface of the first conductive layer to a first depth position. A third conductive layer is connected to a side surface of the first conductive layer in the first depth region in a second direction orthogonal to the stacking direction and the first direction.