3D NAND Integrated Assembly for Channel Pillar Dopant Out-Diffusion
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Solution Overview
Problem
Current methods for forming vertically-stacked memory cells in 3D NAND memory devices face challenges in achieving desired heavily-doped regions in channel material pillars, which are crucial for optimal performance and efficiency.
Innovation Solution
The method involves forming a sacrificial material in a conductive source structure, replacing it with conductively-doped semiconductor material, and out-diffusing dopant to create heavily-doped regions in the channel material pillars, ensuring the desired doping concentration and distribution for select devices like source-side select gates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional doping methods are used to form heavily-doped regions in channel material pillars, then the manufacturing process is simple, but the desired doping concentration and distribution cannot be achieved
Solution Approach 1:
The patent applies preliminary action by first forming a sacrificial material in the source structure, then replacing it with conductively-doped semiconductor material that already contains the desired dopant concentration. This preliminary preparation enables subsequent out-diffusion to achieve the target doping distribution in channel material pillars without requiring complex real-time doping control
Solution Approach 2:
The patent uses an intermediary approach by introducing conductively-doped semiconductor material as a mediator between the source structure and channel material pillars. This intermediary material serves as a dopant source that out-diffuses into the channel material, achieving precise doping concentration and distribution through controlled diffusion rather than direct doping
2Reliability
If heavily-doped regions are not properly formed in channel material pillars, then the manufacturing process is simpler, but the memory device performance and efficiency deteriorate
Solution Approach 1:
The patent applies self-service by enabling the conductively-doped semiconductor material to automatically out-diffuse dopant into the channel material pillars through thermal processing. The system uses itself as the dopant source, eliminating the need for external doping equipment and complex manufacturing steps while ensuring reliable heavily-doped region formation
Solution Approach 2:
The patent changes physical parameters by utilizing thermal energy to drive out-diffusion of dopant from the conductively-doped semiconductor material into the channel material pillars. By controlling temperature and processing time, the desired doping concentration and distribution are achieved, improving memory device performance
3Manufacturing precision
If out-diffusion process is used to create heavily-doped regions, then the desired doping distribution is achieved, but the manufacturing time increases
Solution Approach 1:
The patent merges multiple steps by combining the formation of the dopant source and the doping process into a single integrated sequence. The conductively-doped semiconductor material is formed and then immediately utilized as the dopant source for out-diffusion, eliminating separate doping steps and reducing overall manufacturing cycle time while maintaining precise doping distribution
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 formation of memory devices with improved heavily-doped regions, enhancing the non-leaky 'OFF' characteristics and leaky gate-induced drain leakage (GIDL) characteristics, thereby improving the overall performance and efficiency of the memory cells.
Implementation Method 1
out-diffusing dopant from the conductively-doped second semiconductor material into the first semiconductor material
Data Source
AI summary
Some embodiments include a method in which a first stack is formed to include a metal-containing first layer, a second layer over the first layer, and a metal-containing third layer over the second layer. A first opening is formed to extend through the second and third layers. A sacrificial material is formed within the first opening. A second stack is formed over the first stack. A second opening is formed through the second stack, and is extended through the sacrificial material. First semiconductor material is formed within the second opening. A third opening is formed through the second stack and to the second layer. The second layer is removed to form a conduit. Conductively-doped second semiconductor material is formed within the conduit. Dopant is out-diffused from the conductively-doped second semiconductor material into the first semiconductor material. Some embodiments include integrated assemblies.