Hafnium Precursor Ligand Design for Uniform Film Deposition
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Solution Overview
Problem
The reliability of silicon dioxide-based gate dielectrics in semiconductor devices is reaching its physical limits as devices shrink, necessitating the use of high-k materials like hafnium- or zirconium-based metal oxides for improved performance.
Innovation Solution
The use of hafnium or zirconium-containing compounds, specifically HfCl3(tBuCp) and ZrCl3 derivatives, in vapor deposition processes to form uniform and reactive metal-containing layers on substrates, allowing for the deposition of high-k films with controlled physical properties such as vapor pressure and melting point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional chlorinated hafnium precursors (e.g., HfCl4, HfCl3Cp) are used in vapor deposition, then hafnium oxide films can be deposited, but the precursor delivery is difficult and non-uniform
Solution Approach 1:
The patent modifies the physical and chemical parameters of the precursor by introducing alkyl groups (methyl, ethyl, propyl, butyl) attached to the cyclopentadienyl ring. This changes the precursor from solid or high-melting compounds to low-melting liquids with appropriate vapor pressures, enabling uniform delivery while maintaining deposition capability
Solution Approach 2:
The patent creates composite precursor molecules combining hafnium chloride with substituted cyclopentadienyl ligands. This composite structure integrates the reactivity of chlorinated hafnium with the volatility and stability benefits of organometallic compounds, achieving both ease of delivery and film quality
2Reliability
If conventional precursors are used, then deposition can proceed, but carbon incorporation and current leakage increase
Solution Approach 1:
The patent strategically places alkyl substituents at specific positions on the cyclopentadienyl ring (positions 1, 2, 3, 4, or 5) to optimize the balance between volatility and carbon content. The local modification of the ligand structure controls the overall carbon incorporation in the deposited film
Solution Approach 2:
The patent uses simple alkyl groups (methyl, ethyl, propyl, butyl) as temporary ligands that can be easily removed or minimized during deposition. These short-chain alkyl groups provide the necessary volatility without excessive carbon content, and can be controlled to minimize harmful carbon incorporation
3Reliability
If high-k materials are used to replace SiO2, then gate capacitance improves, but the complexity of deposition processes increases
Solution Approach 1:
The patent develops a universal precursor design platform where substituted cyclopentadienyl ligands can be systematically modified to achieve desired properties. This unified approach replaces multiple different precursor types with a single flexible platform, simplifying the overall deposition process for high-k materials
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 enables easier and more uniform delivery of precursors, reducing carbon incorporation and current leakage, and facilitates the formation of high-quality hafnium or zirconium-containing films suitable for advanced semiconductor applications.
Implementation Method 1
A vapor is introduced into a reaction chamber having at least one substrate, the vapor comprising at least one compound having the formula MCl3(R1R2R3R4R5Cp)
Implementation Method 2
The invention provides a method of forming a metal-containing layer on a substrate... By introducing into the reaction chamber a vapor comprising HfCl3(tBuCp)
Data Source
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AI summary
Disclosed are hafnium- or zirconium-containing compounds. The compounds may be used to deposit hafnium- or zirconium-containing layers using vapor deposition methods such as chemical vapor deposition or atomic layer deposition. The hafnium- or zirconium-containing compounds include a ligand and at least one aliphatic group as substituents selected to have greater degrees of freedom than the substituents disclosed in the prior art.