Low-k Dielectric Films via Precursor Ratio Control
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Solution Overview
Problem
Conventional dielectric materials used in semiconductor fabrication, such as silicon oxide, have higher dielectric constants and porosity, leading to increased electrical interference, water absorption, and susceptibility to corrosion and stress cracking, particularly as device geometries shrink and element densities increase.
Innovation Solution
The method involves introducing organo-silicon precursors with a low carbon-to-silicon atom ratio and reactive atomic oxygen into a deposition chamber to form dielectric layers with lower carbon content, porosity, and wet etch rate ratios, using a multicycle deposition and etching process followed by annealing to create high-quality, low-k silicon oxide films with improved flowability and reduced voids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional CVD techniques are used to deposit silicon oxide, then the film can be formed with acceptable k-value (4.0-4.2), but the film has higher porosity and is more susceptible to water absorption and stress cracking
Solution Approach 1:
The patent changes the chemical composition parameters of the precursor material, specifically using organo-silicon precursors with low carbon-to-silicon atom ratios (less than 8) instead of conventional precursors. This parameter change in the precursor chemistry directly results in deposited films with lower porosity and reduced water absorption while maintaining structural integrity and durability.
Solution Approach 2:
The patent employs composite deposition strategies combining multiple precursors (organo-silicon compounds with specific C:Si ratios) and oxygen precursors in controlled proportions. This composite approach allows optimization of film properties, achieving low porosity and high durability simultaneously by balancing the contributions of different precursor components during the deposition process.
2Reliability
If silicon oxide is doped with fluorine to reduce k-value to 3.4-3.6, then electrical interference is reduced, but the film becomes more complex and requires additional doping processes
Solution Approach 1:
The patent extracts the fluorine doping step from the overall process by achieving the desired low k-value (below 3.0) through precursor selection alone. Instead of depositing conventional silicon oxide and then doping it with fluorine, the invention uses organo-silicon precursors that inherently produce low-k films during deposition, eliminating the separate doping operation and reducing process complexity.
Solution Approach 2:
The patent changes the fundamental approach from post-deposition doping to precursor-based composition control. By selecting organo-silicon precursors with specific carbon-to-silicon atom ratios, the film composition is controlled during deposition to achieve low k-values directly, replacing the need for fluorine doping and simplifying the overall manufacturing process.
3Reliability
If spin-on glass techniques are used to form porous low-k films, then k-value is reduced, but the films have higher wet etch rate ratios and are more prone to corrosion
Solution Approach 1:
The patent changes the material composition parameters by using organo-silicon precursors with low carbon-to-silicon atom ratios, which deposit films with optimized porosity levels. This parameter change achieves low k-values while simultaneously producing films with lower wet etch rate ratios and reduced corrosion susceptibility, unlike the highly porous films produced by spin-on glass techniques.
Solution Approach 2:
The patent uses composite precursor systems combining organo-silicon compounds with controlled carbon content and oxygen precursors. This composite approach creates films with balanced properties: sufficient porosity for low k-value but controlled enough to maintain low wet etch rate ratios and resistance to corrosion, avoiding the extreme porosity of spin-on glass films.
4Reliability
If Si-O-C films are deposited to achieve k-value of 3.0 or less, then electrical interference is minimized, but the films become substantially more porous with higher WERR and cracking
Solution Approach 1:
The patent changes the carbon content parameter by using organo-silicon precursors with specifically controlled carbon-to-silicon atom ratios (less than 8). This parameter control achieves low k-values (below 3.0) while maintaining lower porosity and reduced wet etch rate ratios compared to conventional Si-O-C films, thereby preserving structural integrity and reducing cracking.
Solution Approach 2:
The patent employs composite precursor formulations that balance carbon content from organo-silicon compounds with silicon and oxygen from other precursors. This composite strategy achieves the desired low k-value through controlled carbon incorporation while maintaining film density and structural strength, avoiding the excessive porosity and cracking associated with high-carbon Si-O-C films.
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 results in dielectric films with dielectric constants below 3.0 and wet-etch rate ratios less than 2:1, minimizing electrical interference, reducing water absorption, and enhancing the durability and uniformity of the films.
Implementation Method 1
A plasma may be generated from the precursors in the deposition chamber
Implementation Method 2
reactive atomic oxygen into a deposition chamber to form dielectric layers
Implementation Method 3
introducing an organo-silicon precursor and an oxygen precursor to a deposition chamber... reacting the precursors to form the dielectric layer in the gap
Implementation Method 4
followed by annealing to create high-quality, low-k silicon oxide films with improved flowability and reduced voids
Data Source
AI summary
Methods of depositing a dielectric layer in a gap formed on a substrate are described. The methods include introducing an organo-silicon precursor and an oxygen precursor to a deposition chamber. The organo-silicon precursor has a C:Si atom ratio of less than 8, and the oxygen precursor comprises atomic oxygen that is generated outside the deposition chamber. The precursors are reacted to form the dielectric layer in the gap. Methods of filling gaps with dielectric materials are also described. These methods include providing an organo-silicon precursor having a C:Si atom ratio of less than 8 and an oxygen precursor, and generating a plasma from the precursors to deposit a first portion of the dielectric material in the gap. The dielectric material may be etched, and a second portion of dielectric material may be formed in the gap. The first and second portions of the dielectric material may be annealed.