Low-k Dielectric Film Adhesion via Digital Flow Control
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Solution Overview
Problem
In the fabrication of integrated circuits, there is a challenge in developing carbon doped silicon oxide dielectric films with low dielectric constants that also exhibit strong adhesion to underlying substrates or barrier layers, as inadequate adhesion can lead to delamination and device failure.
Innovation Solution
A method for depositing a low dielectric constant film using a PECVD system, where an organosilicon compound and a porogen compound are flowed at controlled rates with RF power to form an initiation layer, transition layer, and porogen-containing organosilicate dielectric layer, optimizing the flow rates to enhance adhesion and reduce dielectric constant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thin silicon oxide film and transition film are inserted between the carbon doped silicon oxide layer and the underlying barrier layer to enhance adhesion, then adhesion strength is improved, but the dielectric constant increases due to the additional layers
Solution Approach 1:
The patent applies local quality by creating distinct layers with different compositions and properties within the dielectric structure. The initiation layer has high silicon oxide content for adhesion, the transition layer has intermediate composition, and the main low-k layer has high porogen content for low dielectric constant. This spatial variation in material quality allows simultaneous optimization of adhesion and dielectric properties.
Solution Approach 2:
The patent uses composite materials by combining silicon oxide, carbon, and porogen compounds in specific ratios within different layers. The initiation layer is predominantly silicon oxide for strong bonding, while the main low-k layer is a composite of silicon oxide and porous structures achieved through porogen decomposition, providing low dielectric constant while maintaining adequate adhesion.
2Strength
If the organosilicon flow rate is increased to deposit a thicker initiation layer for better adhesion, then adhesion strength is improved, but the dielectric constant increases and the low-k performance is reduced
Solution Approach 1:
The patent applies parameter changes by precisely controlling the organosilicon flow rate and porogen flow rate as key process parameters. The initiation layer is deposited at a first organosilicon flow rate optimized for adhesion, then the flow rate is increased for the transition layer, and finally maintained at a second organosilicon flow rate with porogen for the low-k layer. This dynamic adjustment of flow rate parameters enables optimization of both adhesion and dielectric constant.
Solution Approach 2:
The patent implements dynamics by making the deposition process time-dependent with distinct stages. The flow rates are not static but evolve through the deposition process: initial low flow rate for initiation layer, then increased flow rate for transition layer, and finally maintained at optimized levels for the main low-k layer. This dynamic control allows the system to adapt material composition to functional requirements at different depths.
3Temperature
If plasma processing is used to deposit low-k dielectric layers at lower temperatures, then thermal budget is reduced, but adhesion to underlying substrate and barrier layers becomes more challenging
Solution Approach 1:
The patent applies preliminary action by depositing the initiation layer of pure silicon oxide first, before the main low-k layer. This initiation layer is formed under optimized plasma conditions at lower temperature with specific flow rates to ensure strong chemical bonding to the underlying barrier layer, establishing a robust adhesion foundation before subsequent low-k layer deposition.
Solution Approach 2:
The initiation layer and transition layer serve as intermediary structures between the plasma-deposited low-k layer and the underlying barrier layer. These intermediary layers are specifically designed to bridge the adhesion gap, providing chemical bonding interfaces that accommodate the lower temperature plasma process while ensuring strong overall adhesion of the complete dielectric stack.
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
The method achieves improved adhesion strength and reduced dielectric constant, minimizing film stress and particle defects, thereby enhancing the reliability of the integrated circuit devices.
Implementation Method 1
plasma enhanced chemical vapor deposition (PECVD) allows deposition processes to be performed at substantially lower temperatures
Implementation Method 2
vaporizing the organosilicon compound and flowing the organosilicon compound and a carrier gas into the processing chamber
Implementation Method 3
vaporizing the porogen compound and flowing the porogen compound with a carrier gas into the processing chamber
Data Source
AI summary
A method for depositing a low dielectric constant film by flowing a oxidizing gas into a processing chamber, flowing an organosilicon compound from a bulk storage container through a digital liquid flow meter at an organosilicon flow rate to a vaporization injection valve, vaporizing the organosilicon compound and flowing the organosilicon compound and a carrier gas into the processing chamber, maintaining the organosilicon flow rate to deposit an initiation layer, flowing a porogen compound from a bulk storage container through a digital liquid flow meter at a porogen flow rate to a vaporization injection valve, vaporizing the porogen compound and flowing the porogen compound and a carrier gas into the processing chamber, increasing the organosilicon flow rate and the porogen flow rate while depositing a transition layer, and maintaining a second organosilicon flow rate and a second porogen flow rate to deposit a porogen containing organosilicate dielectric layer.