Horn-Shaped Spacer Layout for TEVA Misalignment Isolation

Solution Overview

Problem

Registration errors during the fabrication of memory devices can lead to misalignment of layers, resulting in read/write errors and shorting issues due to the misalignment of wires and vias with respect to electrodes, which affects the reliability of memory devices like RRAM and FeRAM.

Innovation Solution

A memory device design incorporating a horn-shaped sidewall spacer that separates the top electrode via (TEVA) from the bottom electrode, utilizing differing etch rates of hard mask layers to form a structure that prevents the TEVA from shorting to the bottom electrode, even in the presence of registration errors, by covering outer mask portions and forming a TEVA opening that terminates above the bottom surface of the top electrode within the sidewall spacer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional fabrication processes are used without a horn-shaped sidewall spacer, then the manufacturing process is simpler, but registration errors cause the TEVA to extend past the top electrode and short to the bottom electrode

Engineering Contradiction:

Improveprevention of shorting between TEVA and bottom electrodeVSAvoidstructure of sidewall spacer

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The horn-shaped sidewall spacer is formed in advance during the fabrication process, before the TEVA is created. This preliminary structure extends laterally beyond the top electrode boundaries, so that when registration errors occur during subsequent TEVA formation, the pre-positioned spacer already provides the necessary isolation, preventing the TEVA from shorting to the bottom electrode.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The horn-shaped sidewall spacer acts as an intermediary protective structure between the TEVA and the bottom electrode. By extending laterally beyond the top electrode, it creates a physical barrier that mediates the potential harmful interaction (shorting) between the TEVA and bottom electrode, especially when alignment errors occur.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If the sidewall spacer extends laterally beyond the top electrode, then registration errors are compensated and shorting is prevented, but the fabrication process becomes more complex

Engineering Contradiction:

Improvealignment tolerance for TEVAVSAvoidfabrication process complexity

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The horn-shaped sidewall spacer is formed in advance during the fabrication process, before the TEVA is created. This preliminary structure extends laterally beyond the top electrode boundaries, so that when registration errors occur during subsequent TEVA formation, the pre-positioned spacer already provides the necessary isolation, preventing the TEVA from shorting to the bottom electrode.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The sidewall spacer is designed with a horn shape that changes its lateral extent parameter - extending beyond the top electrode boundaries in specific regions. This geometric parameter modification allows the spacer to provide coverage beyond the nominal electrode area, effectively increasing the alignment tolerance window without requiring changes to the overall device architecture.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If a horn-shaped sidewall spacer is implemented, then TEVA isolation from bottom electrode is improved, but the device structure becomes more complex

Engineering Contradiction:

Improveisolation effectivenessVSAvoidsidewall spacer geometry

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The sidewall spacer is designed with an asymmetric horn shape that extends laterally beyond the top electrode boundaries in specific regions. This asymmetric geometry is strategically positioned to provide coverage where registration errors are most likely to occur, creating effective isolation without requiring symmetric complexity throughout the entire device structure.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The horn-shaped sidewall spacer is formed in advance during the fabrication process, before the TEVA is created. This preliminary structure extends laterally beyond the top electrode boundaries, so that when registration errors occur during subsequent TEVA formation, the pre-positioned spacer already provides the necessary isolation, preventing the TEVA from shorting to the bottom electrode.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20230380309A1Horn shaped spacer for memory devices

Publication Date: 2023.11.23 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

The present disclosure relates to a memory device that includes a bottom electrode, a data storage structure overlying the bottom electrode, a top electrode overlying the data storage structure, a mask overlying the top electrode, and a sidewall spacer extending alongside the data storage structure and alongside the mask. The sidewall spacer extends to a height above an upper surface of the mask. A top electrode via (TEVA) extends through the mask to the top electrode and extends into the sidewall spacer, where a first curved portion of the sidewall spacer extends along a top surface of the mask and is spaced apart from the TEVA.