Capacitor Electrode Edge Recess via Two-Stage Etch
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Solution Overview
Problem
Reactive ion etch (RIE) processes used in manufacturing semiconductor capacitors often cause erosion and damage to dielectric layers, particularly at the edges, which deteriorates the reliability of capacitors.
Innovation Solution
A method involving a two-stage etch process where a first etch process forms capacitors with patterned electrodes, followed by a second etch process that selectively removes portions of the electrodes proximate the edges of the capacitor dielectric, creating recessed electrodes that are pulled back from the edges of the dielectric, thereby minimizing damage and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If RIE processes are used to form capacitor electrodes, then manufacturing efficiency is improved, but dielectric layer edges are damaged and reliability deteriorates
Solution Approach 1:
The patent segments the electrode formation process into two distinct etching stages: a first etch process that forms the initial capacitor electrodes, and a second etch process that selectively removes portions of the electrodes proximate to the dielectric layer edges. This segmentation allows each process to be optimized independently, maintaining manufacturing efficiency while eliminating edge damage.
Solution Approach 2:
The first etch process performs the preliminary action of forming the capacitor electrodes with good manufacturing efficiency. The second etch process then performs the corrective action of removing damaged portions. This preliminary action approach allows the main electrode formation to proceed efficiently while a subsequent step addresses the reliability issue.
2Speed
If RIE processes are used to form capacitor electrodes, then manufacturing speed is improved, but process precision deteriorates due to edge damage
Solution Approach 1:
The electrode formation is segmented into two etching operations. The first operation achieves rapid electrode formation with high manufacturing speed, while the second operation precisely removes damaged portions near the dielectric edges, thereby restoring manufacturing precision without significantly compromising overall speed.
Solution Approach 2:
The second etch process applies local quality by selectively removing electrode material only in the regions proximate to the dielectric layer edges where damage occurs, while leaving the bulk of the electrode structure intact. This localized correction maintains precision without requiring complete re-etching of the entire electrode.
3Device complexity
If a single etch process is used to form capacitor electrodes, then device complexity is reduced, but manufacturing precision deteriorates due to inability to correct edge damage
Solution Approach 1:
The patent divides the electrode formation into two etching processes to achieve manufacturing precision. The first process forms the electrodes, and the second process corrects edge damage. This segmentation adds process steps but enables precise control over electrode geometry and eliminates the trade-off between simplicity and precision.
Solution Approach 2:
Both etching processes use similar RIE technology and can be performed in the same fabrication facility using comparable equipment and materials. This merging of similar process types minimizes the increase in device complexity while achieving the desired precision through the two-stage approach.
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 reliability of capacitors by reducing damage to the dielectric layers and providing an enhanced process window for isolation between capacitors and conductive features, while also simplifying the manufacturing process by potentially reducing the need for multiple lithography masks.
Implementation Method 1
Reactive ion etch (RIE) processes are used to form electrodes of capacitors in some manufacturing processes for semiconductor devices
Data Source
AI summary
Semiconductor devices, methods of manufacture thereof, and methods of manufacturing capacitors are disclosed. In an embodiment, a method of manufacturing a capacitor includes: etching a trench in a workpiece. The trench may extend into the workpiece from a major surface of the workpiece. The method further includes lining the trench with a bottom electrode material and lining the bottom electrode material in the trench with a dielectric material. The dielectric material may have edges proximate the major surface of the workpiece. The method further includes forming a top electrode material over the dielectric material in the trench, and etching away a portion of the bottom electrode material and a portion of the top electrode material proximate the edges of the dielectric material.