Semiconductor Lower Electrode Crystallinity via Segmented CVD PVD
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In semiconductor storage devices like iPCM, poor crystal state and flatness of the lower electrode deteriorate the crystallinity of the memory layer, affecting the memory's properties, as the lowermost recording layer acts as a seed for other layers, necessitating a favorable crystal state and flatness for optimal performance.
Innovation Solution
A semiconductor device configuration where the lower electrode is formed with a lower layer portion embedded in trenches or holes using CVD, and an upper layer portion deposited using PVD, ensuring a favorable crystal structure and flatness, with materials like TiN, VN, ZrN, NbN, or TaN, promoting a superlattice structure in the memory layer for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the lower electrode is formed using conventional deposition methods, then the manufacturing process is simple, but the crystal state and flatness of the surface are poor, deteriorating the crystallinity of the memory layer
Solution Approach 1:
The lower electrode is divided into a lower layer portion and an upper layer portion with different structures and formation methods. The lower layer portion is embedded in trenches or holes to provide mechanical support and control crystal growth direction, while the upper layer portion provides a flat surface for memory layer deposition. This segmentation resolves the contradiction by allowing each portion to be optimized independently for its specific function.
Solution Approach 2:
Different regions of the lower electrode are given different properties: the lower layer portion has a crystal structure in a direction not perpendicular to the base layer surface (embedded in trenches/holes), while the upper layer portion has a crystal structure perpendicular to the base layer surface (flat surface). This local differentiation allows the electrode to simultaneously provide structural support and optimal crystal growth conditions for the memory layer.
2Manufacturing precision
If the lower electrode surface is not flat, then the manufacturing process is simpler, but the crystallinity of the lowermost recording layer deteriorates, affecting memory properties
Solution Approach 1:
The lower layer portion of the lower electrode is formed first by embedding it in trenches or holes before forming the upper layer portion. This preliminary action creates a structured foundation that guides the subsequent formation of the flat upper surface, ensuring both flatness and manufacturability by preparing the structure in advance.
Solution Approach 2:
The lower electrode structure transitions from a two-dimensional flat surface to a three-dimensional structure with trenches or holes. By introducing vertical dimensionality through embedded portions, the design achieves both flat upper surfaces (for memory layer deposition) and structured lower portions (for crystal control), resolving the contradiction between flatness and ease of manufacture.
3Reliability
If the crystal state of the lower electrode is poor, then the manufacturing process is simpler, but the resistance difference and data retention of the memory device deteriorate
Solution Approach 1:
The lower electrode is segmented into functional portions: the lower layer portion embedded in trenches/holes controls crystal growth direction and provides structural stability, while the upper layer portion provides a flat surface. This segmentation enables precise control over the crystal state, ensuring reliable data retention without excessive overall complexity.
Solution Approach 2:
The crystal structure orientation is changed as a key parameter: the lower layer portion has crystal structure in a direction not perpendicular to the base layer, while the upper layer portion has crystal structure perpendicular to the base layer. This parameter change optimizes both data retention (through controlled crystal growth) and maintains manufacturability.
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 configuration improves the memory's property by maintaining a large resistance difference, reducing leak current, and enhancing data retention and endurance by ensuring a flat superlattice structure in the memory layer, leading to better phase-change performance.
Implementation Method 1
A lower layer portion is provided in lower parts of trenches or holes formed in the material layer and has a crystal structure in a direction not perpendicular to a surface of the base layer
Implementation Method 2
An upper layer portion is provided on the lower layer portion in the trenches or the holes and has a crystal structure in a direction substantially perpendicular to the surface of the base layer
Data Source
AI summary
A semiconductor device according to an embodiment comprises a base layer. A material layer is provided on the base layer. A lower layer portion is provided in lower parts of trenches or holes formed in the material layer and has a crystal structure in a direction not perpendicular to a surface of the base layer. An upper layer portion is provided on the lower layer portion in the trenches or the holes and has a crystal structure in a direction substantially perpendicular to the surface of the base layer.