Capacitor Stack Etching to Prevent Aluminum Fluoride Roughness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for manufacturing integrated circuits with capacitors face issues such as the formation of aluminum fluoride layers during etching, leading to roughness and poor electrical connections due to micro-masking phenomena.
Innovation Solution
A method involving sequential chemical and physical plasma etching steps, where the chemical etching is interrupted before reaching the aluminum layer, followed by a neutral gas plasma etching to avoid aluminum fluoride formation, ensuring a smooth conductive layer surface for reliable electrical contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If chemical plasma etching is used to etch the stack, then the etching speed is improved, but aluminum fluoride layer forms causing surface roughness and poor electrical connections
Solution Approach 1:
The etching process is divided into two distinct segments: a first chemical plasma etching step using chlorine-based plasma for high-speed removal of dielectric and electrode materials, followed by a second physical plasma etching step using argon plasma to smoothly etch the aluminum conductive layer without forming aluminum fluoride. This segmentation allows each step to optimize for its specific function, resolving the contradiction between etching speed and surface smoothness.
Solution Approach 2:
The patent changes the plasma composition parameter from chemical (chlorine-based) to physical (argon-based) when etching the aluminum layer. This parameter change prevents the chemical reaction between chlorine and aluminum that forms aluminum fluoride, thereby maintaining surface smoothness while still achieving effective etching of the conductive layer.
2Productivity
If chemical plasma etching reaches the aluminum layer, then complete etching is achieved, but aluminum fluoride formation causes micro-masking phenomena and poor electrical connections
Solution Approach 1:
The etching process is segmented into two phases: the first phase uses chemical plasma to etch through dielectric and electrode layers completely, while the second phase switches to physical plasma specifically for etching the aluminum layer. This ensures complete etching while preventing aluminum fluoride formation that would compromise electrical connection reliability.
Solution Approach 2:
The patent converts the potential harm of chemical plasma reacting with aluminum into a benefit by using it only on non-aluminum layers first, then switching to physical plasma for the aluminum layer. This approach ensures complete removal of all materials while avoiding the harmful aluminum fluoride reaction, thereby improving electrical connection quality.
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
Prevents the formation of aluminum fluoride, resulting in a smoother conductive layer surface for improved electrical connections and enhanced reliability of the capacitor in integrated circuits.
Implementation Method 1
etching, by chemical plasma etching, an upper part of the stack
Implementation Method 2
a first step of chemical plasma etching using a chlorine-based plasma
Implementation Method 3
a second step of chemical plasma etching using a fluorine-based plasma
Implementation Method 4
etching, by physical plasma etching, a lower part of the stack
Implementation Method 5
the physical plasma etching, in step c), is carried out using an argon plasma
Data Source
Figure 1~3
Figure 4~6
Figure 7~9
AI summary
This description relates to a method for manufacturing a capacitor, comprising the following successive steps: a) forming a stack comprising, in order from the top face of a substrate (21), a first conductive layer (13) of aluminum or an aluminum-based alloy, a first electrode (15), a first dielectric layer (17) and a second electrode (19); b) etching, by chemical plasma etching, an upper part of the stack, said chemical plasma etching being interrupted before the top face of the first conductive layer (13); and c) etching, by physical plasma etching, a lower part of the stack, said physical plasma etching being interrupted on the top face of the first conductive layer (13).