Composite Dielectric Etch Stop Layers for Semiconductor Interconnects
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional etch stop layers in semiconductor fabrication have low etch selectivity and high dielectric constants, which can lead to increased capacitance and poor performance in integrated circuits, while materials with low dielectric constants often lack the necessary etch selectivity.
Innovation Solution
The development of composite dielectric materials with low dielectric constants (less than 7) and high densities (at least 2.5 g/cm3), formed by depositing films containing Al, Si, and O, using techniques like atomic layer deposition (ALD) and chemical vapor deposition (CVD), which provide improved etch selectivity and adhesion properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional etch stop layer materials (silicon carbide, silicon nitride) are used, then good etch selectivity is achieved, but dielectric constant is high leading to increased capacitance and RC delay
Solution Approach 1:
The patent applies composite materials by creating a dielectric composite film containing both silicon oxide and aluminum oxide in a layered or mixed structure. This composite approach allows the material to exhibit properties of both components: the low dielectric constant of silicon oxide (k<7) and the high etch selectivity provided by aluminum oxide, thereby resolving the contradiction between low capacitance and good etch selectivity
Solution Approach 2:
The patent changes the material composition parameters by controlling the ratio of silicon oxide to aluminum oxide in the composite film, adjusting dielectric constant, density, and etch selectivity characteristics. By varying these compositional parameters, the material can be optimized to achieve both low dielectric constant and high etch selectivity simultaneously
2Object-generated harmful factors
If low dielectric constant materials are used for etch stop layers, then cross-talk between metal lines is minimized, but etch selectivity versus ILD material deteriorates
Solution Approach 1:
The composite dielectric film combines silicon oxide (providing low dielectric constant k<7 to minimize cross-talk) with aluminum oxide (providing high etch selectivity). This composite structure allows simultaneous achievement of low cross-talk and high etch selectivity, resolving the contradiction between these two properties
3Reliability
If high density materials are used for etch stop layers, then etch selectivity is improved, but dielectric constant increases leading to higher capacitance
Solution Approach 1:
The composite film structure allows high density aluminum oxide regions (providing etch selectivity) to be combined with lower density silicon oxide regions (providing low dielectric constant). The overall composite material achieves both high etch selectivity and low capacitance by leveraging the complementary properties of its constituents
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
These composite dielectric films effectively minimize cross-talk between metal lines, reduce resistance-capacitance delay, and offer excellent etch selectivity, making them suitable for use as etch stop layers in semiconductor processing while maintaining low leakage current and high breakdown voltage.
Implementation Method 1
using techniques like atomic layer deposition (ALD) and chemical vapor deposition (CVD)
Implementation Method 2
using techniques like atomic layer deposition (ALD) and chemical vapor deposition (CVD)
Data Source
AI summary
Dielectric composite films characterized by a dielectric constant (k) of less than about 7 and having a density of at least about 2.5 g/cm3 are deposited on partially fabricated semiconductor devices to serve as etch stop layers. The dielectric composite film in one embodiment includes Al, Si, and O and has a thickness of between about 10-100 Å. The dielectric composite film can reside between two layers of inter-layer dielectric, and may be in contact with metal layers. An apparatus for depositing such dielectric composite films includes a process chamber, a conduit for delivering an aluminum containing precursor to the process chamber, a second conduit for delivering a silicon-containing precursor to the process chamber and a controller having program instructions for depositing the dielectric composite film from these precursors, e.g., by reacting the precursors adsorbed to the substrate with an oxygen-containing species.