High-Purity Alkyl Tin Compound Analysis Through GC Derivatization
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Solution Overview
Problem
Current methods for assaying the purity of monoalkyl tin amides in semiconductor fabrication are slow and lack sensitivity, particularly due to the challenges of direct analysis by GC and HPLC, and existing detectors are expensive and not readily available, making it difficult to meet stringent purity requirements for microelectronics applications.
Innovation Solution
A method involving reacting monoalkyl tin triamide compounds with an alkylating agent to form mixed tetraalkyl tin compounds, followed by gas chromatography to determine the relative amounts of impurities, allowing for sensitive and rapid purity analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If 119Sn NMR spectroscopy is used to assay purity of monoalkyl tin amides, then sensitivity to small structural changes and ease of sample preparation are improved, but analysis time increases significantly and sensitivity to low levels of impurities decreases
Solution Approach 1:
The patent applies preliminary action by converting the monoalkyl tin amide sample into a derivative compound before analysis. The sample is reacted with an alkylating agent to form a derivative that can be analyzed by GC, which is a faster method than direct 119Sn NMR spectroscopy. This preliminary chemical transformation enables the use of a more efficient analytical technique.
Solution Approach 2:
The patent uses an alkylating agent as an intermediary substance to transform the original sample into a derivative form suitable for GC analysis. This intermediary chemical reaction step converts the monoalkyl tin amide into a compound with different analytical properties, enabling faster and more sensitive detection of impurities through GC.
2Productivity
If direct analysis by GC is attempted, then analysis speed is improved, but the extreme sensitivity of the tin-nitrogen bond to water and low vapor pressure of compounds creates analytical difficulties
Solution Approach 1:
The patent applies parameter changes by modifying the chemical structure of the analyte through derivation. The monoalkyl tin amide is chemically transformed into a derivative compound that has altered volatility and stability characteristics, making it suitable for GC analysis. This chemical modification changes the physical parameters of the compound to overcome the limitations of direct GC analysis.
3Ease of operation
If normal phase HPLC is used for direct analysis, then potential for direct analysis of alkyl tin amides is improved, but reproducibility decreases due to trace water in mobile phases causing shifts in retention times
Solution Approach 1:
The patent uses preliminary action by chemically derivatizing the monoalkyl tin amide sample before HPLC analysis. The alkylating agent reacts with the sample to form a derivative that is less sensitive to water interference in the mobile phase, thereby improving the reproducibility of retention times while maintaining the ability to perform direct liquid phase analysis.
4Device complexity
If GC analysis is performed without derivatization, then analysis simplicity is improved, but thermal decomposition occurs because decomposition temperatures are close to or lower than boiling points
Solution Approach 1:
The patent applies parameter changes by chemically transforming the sample into a derivative compound with higher thermal stability. The derivatization reaction modifies the molecular structure to increase the decomposition temperature relative to the boiling point, preventing thermal decomposition during GC analysis while maintaining a relatively simple analytical procedure.
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
Enables detection and quantification of dialkyl tin and tetraalkyl tin impurities at low levels, meeting purity targets of less than 50 ppm, thereby ensuring the quality of monoalkyl tin compounds for semiconductor fabrication.
Implementation Method 1
reacting the sample with a solution of an alkylating agent to form a solution comprising a mixed tetraalkyl tin compound
Implementation Method 2
employing gas chromatography to determine the relative amounts of compounds having formulas (3), (5), (6), and (7) in the solution
Data Source
AI summary
A method for determining the purity of a sample comprising a monoalkyl tin triamide compound and optionally dialkyl tin diamide, tetraalkyl tin, and tetrakis(dialkylamido)tin compounds using gas chromatography is provided. The total content of dialkyl tin diamide, tetraalkyl tin, and tetrakis(dialkylamido)tin compounds detectable by the method may be less than about 40 ppm.