Low-k Dielectric Surface Protection via Flash Activation
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Solution Overview
Problem
Low-k dielectric materials in semiconductor devices are susceptible to processing damage during plasma etching and ashing processes, and the use of hardmasks to protect them increases the effective dielectric constant of the ILD stack, defeating the advantage of low-k dielectrics.
Innovation Solution
A method involving flash activation of the low-k dielectric surface with a reducing plasma to create a chemically reactive surface, followed by exposure to a gaseous precursor to form a protective layer that enhances the surface's robustness against plasma processing without increasing the dielectric constant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hardmask layer is deposited on the low-k dielectric to protect it from plasma damage, then the dielectric's robustness against plasma processing is improved, but the effective dielectric constant of the ILD stack increases, defeating the advantage of low-k dielectrics
Solution Approach 1:
The low-k dielectric surface is pre-treated with a plasma process before cap layer deposition to create a chemically reactive surface. This preliminary action enhances the surface's ability to bond with the cap layer, providing protection against plasma damage without requiring an additional hardmask layer that would increase the dielectric constant.
Solution Approach 2:
The plasma process changes the chemical state of the low-k dielectric surface by creating a chemically reactive surface with enhanced bonding capability. This parameter change in surface chemistry allows the surface to form a strong interface with the cap layer, providing protection while maintaining the low-k properties of the bulk dielectric material.
2Strength
If the low-k dielectric surface is activated with plasma to enhance chemical reactivity, then the surface's robustness and bonding capability are improved, but the dielectric material becomes more susceptible to plasma damage
Solution Approach 1:
The plasma activation is performed as a preliminary step immediately before cap layer deposition, creating a chemically reactive surface that is then quickly protected by the cap layer. This timing ensures the enhanced bonding capability is utilized while minimizing exposure to plasma damage.
Solution Approach 2:
The chemically reactive surface acts as an intermediary layer between the low-k dielectric bulk and the cap layer. This intermediate state enhances bonding while the cap layer provides protection from harmful plasma exposure during subsequent processing.
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 effectively protects low-k dielectric layers from plasma damage while maintaining the low dielectric constant of the ILD stack, allowing for reliable semiconductor device fabrication without the need for additional hardmask layers.
Implementation Method 1
exposing a surface of the dielectric layer to a plasma, thereby forming a chemically reactive surface
Implementation Method 2
exposing the chemically reactive surface to a gaseous precursor after turning off the plasma. The gaseous precursor reacts with the chemically reactive surface
Data Source
AI summary
Embodiments of the invention provide a semiconductor device having dielectric material and its method of manufacture. A method comprises a short (≦2 sec) flash activation of an ILD surface followed by flowing a precursor such as silane, DEMS, over the activated ILD surface. The precursor reacts with the activated ILD surface thereby selectively protecting the ILD surface. The protected ILD surface is resistant to plasma processing damage. The protected ILD surface eliminates the requirement of using a hard mask to protect a dielectric from plasma damage.