3D Memory Source Contact Layer With Vertical Channel Interface

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Solution Overview

Problem

Existing three-dimensional semiconductor devices face challenges in efficiently forming source contact layers with both horizontally and vertically extending portions, which are crucial for optimal performance and integration in memory devices.

Innovation Solution

The proposed solution involves a memory device structure with a source contact layer that includes both horizontally and vertically extending portions. This is achieved through a method of forming source-level material layers, an alternating stack of insulating and conductive layers, and a memory opening fill structure with a vertical semiconductor channel. The source contact layer is formed by replacing sacrificial layers with conductive layers and ensuring the contact layer has an inner cylindrical sidewall contacting the vertical semiconductor channel.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a source contact layer with both horizontally and vertically extending portions is formed, then electrical connectivity and structural integrity are enhanced, but device complexity increases

Engineering Contradiction:

Improveelectrical connectivityVSAvoidsource contact layer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The source contact layer is segmented into distinct horizontally-extending portions and vertically-extending portions, each serving specific functions. The horizontal portions provide broad electrical connection to source regions, while the vertical portions provide side-wall contact to the semiconductor channel, thereby enhancing electrical connectivity without requiring a completely new contact structure

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The source contact layer transitions from a traditional two-dimensional planar contact to a three-dimensional structure with both horizontal and vertical components. The vertically-extending portions rise from the horizontally-extending portions to contact the side walls of the semiconductor channel, adding a vertical dimension to the contact geometry and enabling multi-faceted electrical connectivity

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If a source contact layer with both horizontally and vertically extending portions is formed, then structural integrity is enhanced, but manufacturing complexity increases

Engineering Contradiction:

Improvestructural integrityVSAvoidsource contact layer formation

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Sacrificial layers are deposited and patterned in advance before the final source contact layer is formed. These sacrificial layers define the precise geometry of the horizontally and vertically extending portions, allowing the complex 3D contact structure to be created through a sequence of simpler, pre-planned fabrication steps rather than attempting to form the entire structure in one operation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Sacrificial layers serve as intermediary structures that guide the formation of the source contact layer. These temporary structures are deposited, patterned, and etched to create the desired contact geometry, then removed after transferring their pattern to the source contact layer, simplifying the manufacturing of the complex contact structure

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If the source contact layer contacts the bottommost insulating layer within the alternating stack, then electrical connectivity is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improveelectrical connectivityVSAvoidcontact layer alignment

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The source contact layer structure is designed to self-align with the alternating stack of insulating and semiconductor layers through conformal deposition processes. The vertically-extending portions automatically conform to the sidewalls of the semiconductor channels and extend downward to contact the bottommost insulating layer, with the deposition process itself ensuring proper alignment and positioning without requiring additional alignment steps

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS20250071998A1Three-dimensional memory device with source contact layer having horizontally and vertically extending portions and methods of forming the same

Publication Date: 2025.02.27 SANDISK TECHNOLOGIES LLC

AI summary

A memory device includes source-level material layers containing a lower source-level semiconductor layer, a source contact layer, and an upper source-level semiconductor layer, an alternating stack of insulating layers and electrically conductive layers located over the source-level material layers, a memory opening vertically extending through the alternating stack and into an upper portion of the source-level material layers, and a memory opening fill structure located in the memory opening and including a memory film and a vertical semiconductor channel. The source contact layer includes a horizontally-extending portion and a vertically-extending portion having a greater vertical extent than the horizontally-extending portion, having an inner cylindrical sidewall contacting a bottom portion of the vertical semiconductor channel, and contacting a bottommost insulating layer within the alternating stack.