Semiconductor Memory Cell Structure for Retention Time
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Solution Overview
Problem
Conventional semiconductor memory device fabrication techniques, such as implantation processes, lead to defect structures and undesired doping concentrations, resulting in reduced retention time and scaling challenges, affecting the performance and electrical properties of memory cells.
Innovation Solution
The semiconductor memory device employs a memory cell structure with undoped regions and specific doping concentrations in N-type and P-type regions, coupled with advanced poly plug and gate region materials, to enhance charge storage and retention, and implements a two-step or one-step write operation with control signal voltage waveforms to manage charge accumulation and depletion efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional implantation process is used to manufacture memory cell, then manufacturing process is simple, but defect structures are produced in silicon lattice decreasing retention time
Solution Approach 1:
The patent extracts and eliminates the harmful implantation process that creates defect structures in the silicon lattice. By removing this process step, the invention avoids generating defects that would otherwise decrease retention time, while still achieving the necessary doping through alternative means that do not compromise crystal structure integrity.
Solution Approach 2:
The patent introduces an intermediary approach by using a combination of undoped regions and selectively doped regions separated by oxide layers. This intermediary structure allows charge storage functionality to be achieved without direct implantation into the silicon lattice, thereby avoiding defect formation while maintaining the necessary electrical properties.
2Reliability
If conventional implantation process is used to manufacture memory cell, then manufacturing process is established, but undesired doping concentrations are produced affecting electrical properties
Solution Approach 1:
The patent applies local quality by creating distinct regions with different doping characteristics - undoped regions for charge storage, lightly doped regions for carrier injection, and heavily doped regions for electrical contact. Each region is precisely controlled to have the specific doping concentration needed for its function, avoiding the uniform undesired doping that results from conventional implantation processes.
Solution Approach 2:
The patent changes the doping concentration parameter across different regions of the memory cell. By using undoped, lightly doped, and heavily doped regions in specific configurations, the invention achieves precise control over electrical properties without relying on conventional implantation that produces undesired uniform doping concentrations.
3Productivity
If conventional implantation process is used to manufacture memory cell, then existing technology is used, but lateral and vertical scaling challenges arise
Solution Approach 1:
The patent transitions from planar doping approaches to a three-dimensional structure with oxide layers positioned at different vertical levels. The first oxide layer is positioned between the first and second doped regions, and the second oxide layer is positioned between the second and third doped regions, enabling precise spatial control that facilitates lateral and vertical scaling without the limitations of conventional implantation processes.
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 improves the retention time and scaling capabilities of semiconductor memory devices by minimizing defects and undesired doping effects, enabling better data storage and retrieval with enhanced operational efficiency.
Implementation Method 1
the first P-type region and the N-type region may form a PN junction
Implementation Method 2
majority charge carriers may be injected from the P-type region into the undoped region
Implementation Method 3
A semiconductor memory device may include a memory cell having a memory transistor with an electrically floating body region wherein electrical charge may be stored
Data Source
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AI summary
Techniques for providing a semiconductor memory device are disclosed. In one particular exemplary embodiment, the techniques may be realized as a semiconductor memory device including a plurality of memory cells arranged in an array of rows and columns. Each memory cell including a first region, a a second region, and a body region capacitively coupled to at least one word line and disposed between the first region and the second region. Each memory cell also including a third region, wherein the third region may be doped differently than the first region, the second region, and the body region.