MIM Capacitor Electrode Surface Roughness Control
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Solution Overview
Problem
Existing semiconductor devices with MIM capacitors face challenges in maintaining withstand voltage values and reducing variations as the thickness of the main conductive film increases, as current manufacturing techniques do not adequately address the thickness dependence of the withstand voltage value, leading to performance degradation.
Innovation Solution
A semiconductor device manufacturing method involving the sequential formation of films such as titanium, titanium nitride, aluminum, and titanium nitride layers for the lower electrode, with a specific surface roughness to thickness ratio of 14% or less, to improve the planarity and reduce surface roughness of the electrode, thereby stabilizing the withstand voltage value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of the main conductive film is increased, then the capacitance of the MIM capacitor is increased, but the surface roughness increases and the withstand voltage value decreases with increased variations
Solution Approach 1:
The patent applies parameter changes by controlling the thickness of the aluminum main conductive film within a specific range (50 nm to 200 nm) and managing the surface roughness ratio relative to the insulating film thickness. By optimizing these parameters, the invention achieves adequate capacitance while suppressing surface roughness to maintain high withstand voltage values and reduce variations.
Solution Approach 2:
The patent uses a composite structure consisting of multiple layers including barrier films (titanium, titanium nitride), the main conductive film (aluminum), and insulating films. This composite material approach allows each layer to contribute specific properties: barrier films prevent diffusion, the aluminum film provides conductivity and capacitance, and the insulating film provides dielectric properties, collectively achieving both high capacitance and high withstand voltage.
2Quantity of substance
If the thickness of the main conductive film is increased, then the capacitance is improved, but the planarity of the electrode surface deteriorates
Solution Approach 1:
The patent controls the thickness of the aluminum main conductive film within a specific range (50 nm to 200 nm) and manages the surface roughness ratio relative to the insulating film thickness. By optimizing these parameters, the invention achieves adequate capacitance while suppressing surface roughness to maintain high planarity.
Solution Approach 2:
The patent forms barrier films (titanium and titanium nitride layers) before depositing the aluminum main conductive film. These preliminary barrier films provide a smooth foundation that prevents aluminum grain growth and surface roughening, thereby maintaining planarity even as the aluminum film thickness increases for higher capacitance.
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 effectively suppresses the decrease in withstand voltage value and variations, enhancing the performance and yield rate of MIM capacitors by maintaining a low surface roughness and improving the (111) orientation of the main conductive film, even as the thickness of the main conductive film increases.
Implementation Method 1
a main conductive film containing aluminum is formed
Implementation Method 2
heat treatment is performed at a temperature higher than the formation temperature of the conductive film, thereby reorienting the Al crystal grains contained in the conductive film
Implementation Method 3
reorienting the Al crystal grains contained in the conductive film
Data Source
AI summary
A step of forming a stacked film serving as a lower electrode, a step of forming an insulating film serving as a capacitive film on the stacked film, and a step of patterning the insulating film and the stacked film are performed. In the step of forming the stacked film, a film containing titanium, a film containing titanium and nitrogen, a main conductive film containing aluminum, a film containing titanium, and a film containing titanium and nitrogen are sequentially formed from below. The ratio of the surface roughness of the upper surface of the stacked film to the thickness of the insulating film is 14% or less.