Monoalkyl Tin Triamide Synthesis With Selective Dialkyl Tin Removal
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Solution Overview
Problem
Existing methods for synthesizing monoalkyl tin triamides struggle to achieve high purity levels, particularly in controlling dialkyl tin and other impurities, which can degrade semiconductor performance due to off-gassing and contamination during EUV lithography processes.
Innovation Solution
A method involving lithiation of a dimethylamine solution with controlled stoichiometry and solvent conditions, followed by filtration and vacuum removal of LiCl salt, and optional distillation, to produce monoalkyl tin triamides with purities of at least 99 mol%, minimizing dialkyl tin and other impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional synthesis methods (lithium dimethylamide with alkyl tin trichloride) are used, then monoalkyl tin triamides can be produced, but significant amounts of dialkyl tin and other tin impurities are generated
Solution Approach 1:
The patent changes the stoichiometric parameters of the reaction by using exactly 3.0 equivalents of lithium dimethylamide per equivalent of alkyl tin trichloride, and controls the reaction temperature to remain below 0°C during addition. These parameter changes prevent the formation of dialkyl tin impurities by avoiding excess reagent and controlling reaction kinetics.
Solution Approach 2:
The patent replaces conventional purification methods (distillation, chromatography) with a selective precipitation method using diethyl ether. The dialkyl tin impurities are selectively removed as insoluble ethersolvates, achieving high purity without complex mechanical separation systems.
2Manufacturing precision
If purification processes are applied to reduce impurities, then purity increases, but production time and process complexity increase
Solution Approach 1:
The patent extracts only the harmful dialkyl tin impurities from the reaction mixture by selective precipitation with diethyl ether, rather than attempting to purify the entire product. This targeted extraction achieves high purity in a single step without requiring multiple sequential purification operations.
Solution Approach 2:
The patent discards the precipitated dialkyl tin ethersolvates as waste while recovering the soluble monoalkyl tin triamide in the filtrate. This selective discarding of impurities simplifies the process compared to methods requiring recovery and reprocessing of purified material.
3Speed
If lower reaction temperatures are used to slow substitution reaction, then comproportionation risk increases, but higher temperatures accelerate unwanted side reactions
Solution Approach 1:
The patent performs preliminary cooling of the reaction mixture to below 0°C before adding the lithium dimethylamide solution. This preliminary temperature control prepares the system to undergo the substitution reaction at controlled rates while maintaining conditions that prevent comproportionation, balancing reaction speed and reliability.
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 achieves monoalkyl tin triamides with purities greater than 99 mol%, significantly reducing dialkyl tin impurities and other contaminants, ensuring stable performance in EUV lithography applications.
Implementation Method 1
the synthesis may be performed using lithium dimethylamide and alkyl tin trichloride (amination)
Implementation Method 2
removing the LiCl salt product by filtration
Implementation Method 3
removing the first solvent and the second solvent under vacuum to produce a crude product
Implementation Method 4
optional distillation, to produce monoalkyl tin triamides with purities of at least 99 mol%
Data Source
AI summary
Monoalkyl tin triamide compounds having purity of at least about 99 mol % and the chemical formula RSn(NMe2)3 are described. R1 is selected from RA, RB, and RC; RA is a primary alkyl group having about 1 to 10 carbon atoms, RB is a secondary alkyl group having about 3 to 10 carbon atoms, and RC is a tertiary alkyl group having about 3 to 10 carbon atoms; each R2 is independently an alkyl group having about 1 to 10 carbon atoms; and a content of R1Sn(NR22)2(N(R2)CH2NR22) is less than about 1 mol %. Methods for synthesizing, purifying, and storing these compounds are also provided. The monoalkyl tin compounds may be used for the formation of high-resolution EUV lithography patterning precursors and are attractive due to their high purity and minimal concentration of dialkyl tin and other tin impurities.