3D NAND Source Implant Structure for Controlled Source Contact Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional 3D NAND memory devices face processing challenges such as over-etching and corrosion of conductive materials due to the use of multiple polysilicon materials, which can lead to inefficiencies in etching and contact formation in the source stack.
Innovation Solution
Incorporating a source implant region below a slit in the source stack to form a lateral contact with the channel pillars, providing additional etching margin and protection to the underlying conductive materials, while allowing selective removal of polysilicon materials without exposing the source stack to etching conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If multiple polysilicon materials are used in the source stack, then contact formation is achieved, but over-etching occurs and conductive materials are corroded
Solution Approach 1:
A sacrificial material is introduced as an intermediary layer between the polysilicon materials and the etching process. This sacrificial material is selectively removed to enable contact formation while protecting the underlying conductive materials from over-etching and corrosion, thus resolving the contradiction between ease of manufacture and manufacturing precision
Solution Approach 2:
The sacrificial material is deposited and patterned before the final contact formation step. This preliminary action creates a protective mask that prevents over-etching during subsequent processing, allowing contact formation to proceed without corroding the conductive materials beneath
2Ease of operation
If etching is performed to form lateral contact, then contact region is accessed, but underlying source stack is exposed to etching conditions and corroded
Solution Approach 1:
The sacrificial material serves as a protective intermediary during the lateral etching process. It allows the etch to access the contact region while preventing the etchant from reaching and corroding the underlying source stack, thus enabling contact access while maintaining source stack integrity
Solution Approach 2:
The sacrificial material is designed to be selectively removed by the etching process. The harmful etching action is converted into a beneficial process that shapes the contact region while the sacrificial material protects vulnerable areas, transforming potential damage into precise contact formation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances control over etching into the source contact region, reduces corrosion, and improves the integrity of the source stack by allowing lateral etching of source contact material without affecting the underlying stack, thereby improving the fabrication process and device performance.
Implementation Method 1
By including the source implant region in a source stack of the electronic device, etching into and through the source contact is controllable. The source implant region protects underlying conductive materials of the source stack, and improves sidewall etching into the source contact region.
Data Source
AI summary
Electronic devices comprising a source stack comprising one or more conductive materials, a source implant region within a top portion of the source stack, a source contact adjacent to the source stack, sidewalls of the source contact vertically adjacent to the source implant region, a doped semiconductive material adjacent to a source contact, tiers of alternating conductive materials and dielectric materials adjacent to the doped semiconductive material, and pillars extending through the tiers, the doped semiconductive material, and the source contact and into the source stack. Additional electronic devices are also disclosed, as are related methods and electronic systems.