Fluorine-Doped Dielectric Bonding to Prevent Delamination
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Solution Overview
Problem
Existing bonding methods for semiconductor devices using dielectric layers struggle with achieving high bonding energy, particularly due to issues like delamination caused by moisture desorption and reactive or unbonded fluorine in fluorine-doped dielectric layers.
Innovation Solution
The use of fluorine-doped dielectric layers, such as FSG layers, with a low concentration of fluorine (less than 4%), annealing, and exposure to hydrogen plasma prior to bonding, to improve bond strength by reducing unreacted fluorine and moisture absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If fluorine-doped dielectric layers are used for bonding, then bonding energy is improved, but delamination occurs due to moisture desorption and reactive fluorine
Solution Approach 1:
The patent applies preliminary action by annealing the fluorine-doped dielectric layer before bonding to remove moisture, and by exposing it to hydrogen plasma to reduce reactive fluorine content. These pre-treatment steps prevent delamination issues that would occur during subsequent bonding and operation, thereby resolving the contradiction between achieving high bonding energy and preventing delamination.
Solution Approach 2:
The patent changes the fluorine concentration parameter from typical high levels (5-10%) to a reduced range (2-4%), and controls the doping level during deposition. This parameter modification reduces the amount of reactive fluorine and moisture absorption while maintaining the dielectric properties, thus achieving both high bonding energy and delamination resistance.
2Quantity of substance
If high concentration of fluorine is used in dielectric layer, then dielectric constant is reduced, but bonding performance deteriorates due to unreacted fluorine
Solution Approach 1:
The patent optimizes the fluorine concentration parameter to a specific range (2-4%) rather than using high concentrations. This parameter change achieves the desired dielectric constant reduction while avoiding the bonding problems associated with excessive unreacted fluorine, thus resolving the contradiction between dielectric performance and bonding strength.
Solution Approach 2:
The patent converts the potentially harmful effect of fluorine (reactivity causing bonding failures) into a beneficial effect by controlling its concentration and using hydrogen plasma treatment. The fluorine remains present to provide low dielectric constant but is treated to eliminate its harmful reactivity, thus achieving both electrical and mechanical performance.
3Quantity of substance
If fluorine-doped dielectric layer is deposited with standard fluorine concentration, then dielectric properties are improved, but moisture absorption increases causing bonding failures
Solution Approach 1:
The patent reduces the fluorine concentration parameter from standard levels to a lower range (2-4%), which decreases the material's affinity for moisture while maintaining adequate dielectric properties. This parameter change resolves the contradiction between achieving good dielectric performance and minimizing moisture absorption that causes bonding failures.
Solution Approach 2:
The patent applies preliminary annealing treatment to the fluorine-doped dielectric layer before bonding, which removes absorbed moisture and stabilizes the material structure. This pre-drying action prevents moisture-related bonding failures while preserving the dielectric properties, thus resolving the contradiction.
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 enables the achievement of higher average bonding energy, reducing the risk of delamination and enhancing the reliability of semiconductor device assemblies, particularly in high-performance and high-frequency applications.
Implementation Method 1
exposing the fluorine-doped dielectric layer to hydrogen-containing plasma
Implementation Method 2
causing the unbonded fluorine to react (e.g., to form HF)
Implementation Method 3
annealing the fluorine-doped dielectric layer prior to bonding may improve bond strength by removing moisture
Data Source
AI summary
A method of bonding substrates comprises depositing a fluorine-doped dielectric layer on a first substrate, exposing the fluorine-doped dielectric layer to a hydrogen-containing plasma, and directly bonding the fluorine-doped dielectric layer to a surface of a second substrate without the use of an intervening adhesive.