Conductive Polymer Support for High Aspect Ratio Capacitor Etching
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Solution Overview
Problem
The dry etching of silicon dioxide in semiconductor fabrication results in tapered profiles and feature twisting due to its physical sputtering nature, leading to inefficiencies in forming high aspect ratio openings, which affects the precision and effectiveness of microelectronic structures.
Innovation Solution
Using a conductive polymer support material with at least 25 atomic percent carbon, which is initially conductive and then processed to reduce conductivity, allowing for chemically driven plasma etching with reduced feature charging and twisting, enabling the formation of high aspect ratio structures without the need for subsequent material replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If silicon dioxide is used as the support material for dry etching, then the etching process can be performed, but the etch profile becomes tapered and features exhibit twisting due to physical sputtering nature
Solution Approach 1:
The patent changes the material parameter from silicon dioxide to a conductive polymer with at least 25 atomic percent carbon. This material substitution fundamentally alters the etching mechanism from physical sputtering to chemical etching, eliminating the tapered profile and feature twisting while enabling high aspect ratio openings with aspect ratios of at least 20:1
Solution Approach 2:
The conductive polymer support material represents a composite approach, combining polymer matrix with high carbon content (at least 25 at%) to achieve both structural support and enhanced etching characteristics. This composite material provides both mechanical integrity and chemical reactivity for precise etching
2Length of moving object
If the aspect ratio of openings is increased to accommodate smaller feature dimensions, then device scaling is achieved, but twisting phenomenon occurs and etching effectiveness decreases
Solution Approach 1:
By changing the support material to a conductive polymer with specific carbon content, the patent enables maintenance of profile accuracy even at high aspect ratios of at least 20:1. The chemical etching mechanism provides consistent etch rates throughout the depth of the opening, preventing the twisting that normally occurs during scaling to smaller dimensions
3Reliability
If silicon dioxide is used as the dielectric material, then insulation is provided, but feature charging occurs due to its insulative nature, creating vertical potential gradients that retard ion flux
Solution Approach 1:
The patent changes the electrical parameter of the support material by using a conductive polymer instead of insulating silicon dioxide. The conductive nature of the polymer (with at least 25 at% carbon) dissipates charge accumulation, eliminating vertical potential gradients and aspect ratio dependent etching while maintaining structural integrity for capacitor formation
4Manufacturing precision
If lateral potential gradients exist during etching, then feature asymmetries occur, but these can result from various sources including photo irregularities and plasma deposition variations
Solution Approach 1:
By changing to a conductive polymer support material, the patent eliminates the accumulation of lateral potential gradients that cause feature asymmetries. The conductive property allows rapid dissipation of any localized charge imbalances, ensuring symmetric etching profiles even when subjected to variations in photo lithography or plasma deposition
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 etching precision and reduces feature distortion, enabling the formation of high aspect ratio structures with improved conductivity and insulation properties, enhancing the efficiency of semiconductor fabrication.
Implementation Method 1
chemically driven plasma etching
Implementation Method 2
chemically driven plasma etching
Implementation Method 3
processing the support material to effect a phase change
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
A capacitor forming method includes forming an electrically conductive support material over a substrate, with the support material containing at least 25 at% carbon. The method includes forming an opening through at least the support material where the opening has an aspect ratio of at least 20: 1 within a thickness of the support material. After forming the opening, the method includes processing the support material to effect a reduction in conductivity, and forming a capacitor structure in the opening.