3D Memory Device Non-Epitaxial Support Pillars
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Solution Overview
Problem
Current three-dimensional memory devices face challenges in efficiently forming monolithic memory arrays with multiple levels on a single semiconductor substrate, where existing methods struggle to prevent semiconductor material deposition in support openings and achieve optimal epitaxial channel growth in memory openings.
Innovation Solution
A method involving the formation of alternating stacks of insulating and sacrificial material layers, where impurity species are implanted to prevent semiconductor material deposition in support openings, allowing selective epitaxial growth only in memory openings, and simultaneous formation of memory and support pillar structures on epitaxial channel portions and impurity-doped semiconductor material portions, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If semiconductor material is deposited in support openings during epitaxial growth, then material utilization is improved, but structural integrity and device performance deteriorate due to unwanted semiconductor material formation in non-active regions
Solution Approach 1:
The patent applies local quality by implanting impurity species selectively into specific regions of the semiconductor substrate - namely, into portions underlying support openings while preventing implantation into portions underlying memory openings. This creates spatially differentiated material properties where doped regions suppress epitaxial growth and undoped regions promote it, allowing the same deposition process to achieve different outcomes in different locations.
Solution Approach 2:
The patent employs preliminary action by performing impurity implantation into the semiconductor substrate before the epitaxial deposition step. This pre-treatment modifies the substrate properties in advance, ensuring that when semiconductor material is subsequently deposited, it only grows in desired locations (memory openings) and not in support openings, thereby preventing the harmful effect before it can occur.
2Manufacturing precision
If selective epitaxial growth is implemented to grow channels only in memory openings, then manufacturing precision is improved, but process complexity increases due to additional selective deposition steps
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition of the semiconductor substrate through impurity implantation. By changing the doping concentration and type in specific regions, the patent alters the epitaxial growth characteristics - doped regions become resistant to epitaxial growth while undoped regions remain receptive. This parameter modification enables selective growth control without requiring complex masking or multiple deposition steps.
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 enables the creation of monolithic three-dimensional memory devices with efficient epitaxial channel growth in memory openings while avoiding semiconductor material deposition in support openings, enhancing the structural integrity and performance of the memory array.
Implementation Method 1
An impurity species is implanted to first portions of the semiconductor substrate underlying the support openings to form impurity-doped semiconductor material portions
Implementation Method 2
Epitaxial channel portions are grown from the second portions of the semiconductor substrate in bottom regions of the memory openings employing a selective deposition process
Data Source
Figure 1
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Figure 3A~3B
AI summary
Memory openings and support openings are formed through an alternating stack of insulating layers and spacer material layers over a semiconductor substrate. Deposition of a semiconductor material in the support openings during formation of epitaxial channel portions in the memory openings is prevented by Portions of the semiconductor substrate that underlie the support openings are converted into impurity-doped semiconductor material portions. During selective growth of epitaxial channel portions from the semiconductor substrate within the memory openings, growth of a semiconductor material in the support openings is suppressed due to the impurity species in the impurity-doped semiconductor material portions. Memory stack structures and support pillar structures are subsequently formed over the epitaxial channel portions and in the support openings, respectively. The support pillar structures are formed with an outermost dielectric layer to prevent a leakage path to electrically conductive layers to be subsequently formed.