3D Memory Channel Height Equalization Using a Polishing Stop Layer
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Solution Overview
Problem
The increasing integration density of semiconductor memory devices has reached a limit, and three-dimensional semiconductor memory devices face challenges in achieving uniform and reliable memory cell characteristics due to variations in channel structure heights during manufacturing.
Innovation Solution
A method of manufacturing semiconductor devices involves forming channel structures with different heights, followed by polishing to equalize their heights, and removing the polishing stop layer to ensure uniformity and stability of the memory cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If channel structures are formed with different heights in three-dimensional semiconductor memory devices, then manufacturing flexibility is improved, but manufacturing precision deteriorates due to non-uniform channel structure heights
Solution Approach 1:
A polishing stop layer is introduced as an intermediary element between the channel structures and the polishing process. This layer has controlled thickness and material properties that enable precise control of the polishing depth, ensuring that channel structures are polished to substantially equal heights while maintaining manufacturing flexibility in forming channel structures with different initial heights
Solution Approach 2:
The polishing process parameters are controlled based on the thickness of the polishing stop layer. By adjusting the polishing depth to match the polishing stop layer thickness, the channel structures are polished to substantially equal heights. This parameter control resolves the contradiction between manufacturing flexibility and precision
2Manufacturing precision
If polishing is performed to equalize channel structure heights, then manufacturing precision is improved, but device complexity increases due to additional polishing and removal steps
Solution Approach 1:
The polishing stop layer is formed in advance before the channel structures are created. This preliminary action establishes a predetermined polishing depth reference, simplifying the subsequent polishing process and reducing the complexity of controlling channel structure height uniformity
Solution Approach 2:
The polishing stop layer serves as a mediator that simplifies the polishing process. Instead of complex real-time monitoring and adjustment during polishing, the predetermined stop layer provides a clear endpoint, reducing process complexity while maintaining high manufacturing precision
3Manufacturing precision
If the polishing stop layer is retained in the device structure, then manufacturing precision is maintained, but device purity deteriorates due to residual stop layer material
Solution Approach 1:
The polishing stop layer is completely removed after serving its purpose of controlling channel structure heights. This extraction of the stop layer eliminates residual material that would compromise device purity, while the manufacturing precision benefit is retained through the polishing process that equalized channel structure heights
Solution Approach 2:
The polishing stop layer is discarded after use as a polishing depth reference. Its temporary presence enables precise channel structure height control, and its complete removal ensures no residual material remains to affect device purity or performance
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 results in channel structures with substantially equal heights, leading to uniform memory cell characteristics and improved operational reliability of three-dimensional semiconductor memory devices.
Implementation Method 1
polishing the substrate and the channel structures to expose the polishing stop layer
Data Source
AI summary
A method of manufacturing a semiconductor device may include forming a polishing stop layer on a substrate, forming a stack on the polishing stop layer, forming channel structures extending through the stack and the polishing stop layer and having different heights, polishing the substrate and the channel structures to expose the polishing stop layer, and removing the polishing stop layer.