3D DRAM Blind Recess Trimming Without Aperture Enlargement
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Solution Overview
Problem
Existing methods for forming 3D DRAM devices face challenges in properly trimming blind recesses without increasing the width of access apertures, leading to inefficient use of space and potential mechanical failures.
Innovation Solution
The method involves forming alternating pairs of semiconductor and sacrificial material layers on a substrate, depositing a protective material layer, laterally recessing the sacrificial material, and trimming the semiconductor material while maintaining the access aperture width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional trimming methods are used on blind recesses, then the recess can be trimmed, but the access aperture width increases
Solution Approach 1:
The patent segments the blind recess trimming process into multiple controlled steps: forming alternating sacrificial and semiconductor material layers, selectively removing sacrificial material to create recesses, and trimming only the exposed semiconductor material portions. This segmentation allows precise control of recess dimensions without affecting the overall access aperture width, as each layer is processed independently.
Solution Approach 2:
The patent applies preliminary action by forming the alternating layers of sacrificial and semiconductor materials before the trimming operation. The sacrificial material is strategically placed to define the future recess boundaries, and its selective removal creates precisely defined exposure patterns that guide subsequent trimming operations, ensuring dimensional control is achieved before final trimming occurs.
2Area of moving object
If the access aperture width is maintained, then space efficiency is improved, but trimming quality may deteriorate
Solution Approach 1:
The patent applies local quality by creating different material compositions at different locations within the structure. The alternating layers have distinct properties: sacrificial material (e.g., silicon germanium) is designed for selective removal, while semiconductor material (e.g., silicon) retains structural integrity. This local differentiation allows the trimmed sections to achieve high quality with precise dimensional control while maintaining overall aperture width constraints.
Solution Approach 2:
The patent utilizes parameter changes by varying the thickness, composition, and crystalline structure of alternating material layers. By controlling the thickness ratio (semiconductor layer thickness greater than or about 400% more than sacrificial material layer thickness) and material properties, the process enables precise trimming control without requiring aperture width expansion, as each layer's parameters are optimized for its specific function.
3Volume of moving object
If recess dimensions are increased, then device performance is improved, but mechanical stability may worsen
Solution Approach 1:
The patent employs composite materials by creating structures with alternating layers of different semiconductor materials (e.g., silicon and silicon germanium). This composite approach allows the formation of larger recess volumes while maintaining mechanical stability, as the different materials provide complementary properties: one material facilitates selective removal for recess formation, while the other provides structural support and mechanical integrity to the enlarged structure.
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 allows for excellent dimension control in blind recesses without sacrificing the quality of the trimmed section, enabling increased recess dimensions and improved mechanical stability of 3D DRAM devices.
Implementation Method 1
the protective material layer is formed by selective oxidation or nitridation of the exposed lateral ends of the semiconductor material
Implementation Method 2
the protective material layer is formed by selective oxidation or nitridation of the exposed lateral ends of the semiconductor material
Implementation Method 3
the protective material layer is formed by directional deposition on the exposed lateral ends of the semiconductor material
Data Source
AI summary
Embodiments of the present technology may include semiconductor processing methods and systems. Methods and systems may include providing a substrate to a processing region of a semiconductor processing chamber, where the substrate includes one or more alternating pairs of a semiconductor material layer and a sacrificial material layer. Methods include forming one or more vertically extending features through the one or more alternating pairs of semiconductor material layer and sacrificial material layer, forming one or more sidewalls having alternating exposed lateral ends of the semiconductor material and the sacrificial material. Methods include forming a protective material layer over the exposed lateral ends of the semiconductor material layer. Methods include laterally recessing at least a portion of the sacrificial material layer from the one or more vertically extending features and trimming a portion of the semiconductor material layer adjacent to the one or more vertically extending features.