Flowable Dielectric Curing via Oxygen Pre-Soak
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Solution Overview
Problem
In semiconductor manufacturing, the reduction in device geometries leads to increased interconnect capacitance, and traditional low k materials face reliability and manufacturability challenges, particularly due to reduced UV penetration during the curing process of flowable dielectric layers, which affects the curing efficiency.
Innovation Solution
A method involving the deposition of a flowable dielectric layer on a substrate, followed by an oxygen-containing gas pre-soak and subsequent UV radiation exposure, which enhances UV penetration and curing efficiency by stabilizing the refractive index and preventing surface absorption issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If UV radiation is applied to cure the flowable dielectric layer, then the surface curing is improved, but the UV penetration depth is reduced due to increased surface reflectivity and absorption
Solution Approach 1:
The patent applies a preliminary oxygen plasma treatment to the flowable dielectric layer before UV curing. This pre-treatment modifies the surface properties of the layer, reducing the reflectivity and absorption of UV radiation at the surface. By performing this action before the main UV curing process, the patent ensures that UV light can penetrate deeper into the layer, achieving more uniform curing throughout the entire thickness while maintaining effective surface curing.
2Ease of manufacture
If highly flowable precursor materials are used to fill substrate gaps, then the fillability is improved, but the UV curing efficiency is reduced due to material properties
Solution Approach 1:
The patent changes the physical and chemical parameters of the flowable dielectric layer by exposing it to oxygen plasma before UV curing. This treatment modifies the material's optical properties, specifically reducing its UV absorption coefficient and adjusting its refractive index. These parameter changes enable the material to maintain its high flowability for good gap fill while simultaneously improving its UV curing characteristics, resolving the contradiction between fillability and curing efficiency.
3Strength
If the flowable dielectric layer is cured with UV radiation, then the crosslinking and densification are improved, but the thermal stress is increased
Solution Approach 1:
The patent replaces the conventional thermal curing mechanism with a photochemical curing mechanism using UV radiation. By using photopolymerization instead of thermal crosslinking, the process achieves effective curing at lower temperatures, thereby reducing thermal stress in the dielectric layer while still maintaining improved film density and crosslinking through the photochemical reaction.
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 allows for more complete and uniform curing of flowable dielectric layers, improving fillability in high aspect ratio features and reducing thermal stress, while maintaining a low thermal budget, thus addressing the challenges of reduced UV penetration and material reliability.
Implementation Method 1
delivering an oxygen-containing gas to the substrate and the processing region, the flowable dielectric layer being immersed in the oxygen-containing gas for a period of time
Implementation Method 2
exposing the soaked dielectric layer to UV radiation, wherein the UV radiation at least partially cures the soaked dielectric layer
Data Source
AI summary
Methods for depositing and curing a flowable dielectric layer are disclosed herein. Methods can include forming a flowable dielectric layer, immersing the flowable dielectric layer in an oxygen-containing gas, purging the chamber and curing the layer with UV radiation. By curing the layer after an oxygen-containing gas pre-soak, the layer can be more completely cured during the UV irradiation.