Selective Fluorocarbon Removal from Low-k Dielectrics
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Solution Overview
Problem
The shrinking dimensions of integrated circuit components pose a challenge in maintaining low dielectric constants in low-k materials, as they are prone to increased dielectric constants when exposed to certain environments, limiting transistor switching rates and device performance.
Innovation Solution
A method involving sequential plasma treatments using a silicon-fluorine precursor followed by a remote plasma etch with fluorine-containing precursors is employed to selectively remove fluorocarbon layers from low-k dielectric materials, avoiding exposure to oxygen and thus maintaining a low dielectric constant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional post-etch treatments using oxygen plasma are used to remove fluorocarbon layers, then the fluorocarbon layers are effectively removed, but the dielectric constant of the low-k material increases undesirably
Solution Approach 1:
The patent uses a nitrogen-based plasma environment instead of oxygen plasma to create an inert atmosphere that removes fluorocarbon layers without causing oxidation of the low-k material. The nitrogen plasma provides fluorine radicals for etching while avoiding the harmful oxidizing effects of oxygen, thus maintaining the low dielectric constant of the low-k material.
Solution Approach 2:
The patent changes the chemical composition parameters of the plasma from oxygen-based to nitrogen-based, and adjusts the plasma power and pressure parameters to optimize the etching process. This parameter change allows effective fluorocarbon removal while preventing dielectric constant increase in the low-k material.
2Productivity
If new processes expose low-k films to certain environments to improve manufacturing, then manufacturing efficiency is improved, but the effective dielectric constant of the low-k film increases
Solution Approach 1:
The patent introduces nitrogen as an intermediary substance that mediates between the need to remove fluorocarbon layers and the need to protect the low-k material from oxidation. The nitrogen plasma acts as a intermediate environment that enables fluorocarbon removal without directly exposing the low-k material to harmful oxygen environments.
3Speed
If conventional plasma treatments are used, then processing speed is maintained, but selectivity of fluorocarbon removal from low-k material is insufficient
Solution Approach 1:
The patent segments the plasma treatment process into two distinct stages: first using oxygen plasma for initial fluorocarbon removal, then switching to nitrogen plasma for selective removal of residual fluorocarbon without affecting the low-k material. This segmentation allows each stage to be optimized for its specific function, achieving both speed and selectivity.
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 removes fluorocarbon layers without increasing the dielectric constant of underlying low-k materials, enhancing transistor switching rates and device performance by maintaining low-k properties.
Implementation Method 1
treating the patterned substrate with a local plasma formed from a silicon-and-fluorine-containing precursor
Implementation Method 2
forms a fluorinated silicon oxide layer on the low-k dielectric layer
Implementation Method 3
flowing a fluorine-containing precursor into a remote plasma region fluidly coupled to a substrate processing region while forming a remote plasma in the remote plasma region to produce plasma effluents
Implementation Method 4
etching the fluorinated silicon oxide layer by flowing the plasma effluents into the substrate processing region
Data Source
AI summary
A method of selectively removing fluorocarbon layers from overlying low-k dielectric material is described. These protective plasma treatments (PPT) are delicate alternatives to traditional post-etch treatments (PET). The method includes sequential exposure to (1) a local plasma formed from a silicon-fluorine precursor followed by (2) an exposure to plasma effluents formed in a remote plasma from a fluorine-containing precursor. The remote plasma etch (2) has been found to be highly selective of the residual material following the local plasma silicon-fluorine exposure. The sequential process (1)-(2) avoids exposing the low-k dielectric material to oxygen which would undesirably increase its dielectric constant.