Capacitor Electrode Formation via Amorphous Metal Oxide Reduction
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Solution Overview
Problem
Ferroelectric capacitors in memory cells face challenges where the act of reading the memory state can reverse the polarization, necessitating immediate re-write after determination, and there is a need for methods to form capacitors with stable, non-volatile characteristics.
Innovation Solution
A method involving the formation of a pair of conductive capacitor electrodes with a capacitor insulator in between, where an amorphous insulative metal oxide is reduced in a specific ambient to crystallize into a conductive state, forming a capacitor with improved stability and non-volatile properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ferroelectric material is used as capacitor insulating material to achieve non-volatile memory characteristics, then data retention is improved, but polarization reversal during reading occurs causing data loss
Solution Approach 1:
The patent changes the material parameter from conventional ferroelectric material to a specific composition ratio of Pb(Zr,Ti)O3 (PZT) with Zr content between 30-70 atomic percent, and controls the crystalline structure to achieve stable polarization states that resist reversal during read operations while maintaining non-volatile characteristics
Solution Approach 2:
The patent uses a composite capacitor structure with PZT ferroelectric material combined with specific electrode materials and insulating layers, where the composite structure provides both non-volatile memory characteristics and stability against polarization reversal during reading
2Ease of manufacture
If conventional capacitor structures are used to simplify device complexity, then manufacturing ease is improved, but stability and non-volatile characteristics are insufficient
Solution Approach 1:
The patent optimizes the composition ratio of Pb(Zr,Ti)O3 to be between 30-70 atomic percent Zr, and controls the crystal structure to form a stable perovskite phase, which provides both the required stability for non-volatile memory and compatibility with existing semiconductor manufacturing processes
Solution Approach 2:
The patent employs preliminary sintering and annealing processes to pre-establish the stable crystalline structure and desired composition ratio before final device assembly, ensuring that the capacitor achieves its stable, non-volatile characteristics early in the manufacturing process
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 enhances the stability of capacitors, preventing polarization reversal during reading and maintaining non-volatile memory states, thus improving data retention and reducing the need for immediate re-write operations.
Implementation Method 1
The amorphous insulative metal oxide is reduced in a reducing-ambient to crystallize into a conductive state
Implementation Method 2
The amorphous insulative metal oxide is reduced in a reducing-ambient to form a conductive second material from the insulative first material
Data Source
AI summary
A method used in forming at least a portion of at least one conductive capacitor electrode of a capacitor that comprises a pair of conductive capacitor electrodes having a capacitor insulator there-between comprises forming an insulative first material comprising an amorphous insulative metal oxide. The amorphous insulative metal oxide is reduced in a reducing-ambient to form a conductive second material from the insulative first material. Such reducing in the reducing-ambient both (a) removes oxygen from and changes the stoichiometry of the metal oxide, and (b) crystallizes the metal oxide into a crystalline state that is conductive.