Semiconductor IPA Purification Using Adsorption and Distillation
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Solution Overview
Problem
Conventional methods for purifying isopropyl alcohol (IPA) used in semiconductor cleaning processes fail to meet strict purity and impurity specifications, particularly in removing diacetone alcohol, moisture, triisopropyl borate, and metal impurities, leading to potential defects in semiconductor manufacturing.
Innovation Solution
A method involving an adsorption process using molecular sieves 3A, 4A, 10X, and 13X, followed by a distillation process with controlled temperature and reflux ratio, to remove diacetone alcohol, triisopropyl borate, and metal impurities, ensuring IPA meets semiconductor-grade standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional purification methods are used for industrial IPA, then the purification process is simple, but the purity of IPA cannot meet semiconductor-grade standards (99.999% or more)
Solution Approach 1:
The purification process is divided into multiple sequential stages: first adsorption process using molecular sieves 3A or 4A, second adsorption process using molecular sieves 10X or 13X, first distillation process, and second distillation process. Each stage targets specific impurities and progressively increases purity to meet semiconductor-grade standards.
Solution Approach 2:
The patent employs parameter changes including temperature control during distillation (82°C or less), reflux ratio control (1.5 or more), and sequential use of different molecular sieve types with varying pore sizes and adsorption characteristics to optimize removal of different impurities at each stage.
2Manufacturing precision
If simple adsorption process is used, then the process is easy to operate, but diacetone alcohol cannot be completely removed
Solution Approach 1:
The adsorption process is segmented into two sequential steps using different molecular sieve types. The first adsorption process uses molecular sieves 3A or 4A for initial purification, and the second adsorption process uses molecular sieves 10X or 13X to completely remove diacetone alcohol and other remaining impurities.
Solution Approach 2:
The patent utilizes molecular sieves with specific pore sizes and structures (3A, 4A, 10X, 13X) that selectively adsorb different molecules based on their size and polarity, enabling complete removal of diacetone alcohol through the second adsorption process.
3Productivity
If distillation temperature is increased to remove impurities faster, then productivity improves, but metal impurities and boron compounds cannot be effectively removed
Solution Approach 1:
The patent maintains distillation temperature at 82°C or less and reflux ratio at 1.5 or more to prevent decomposition and ensure effective removal of heat-sensitive impurities including metal compounds and boron compounds, while still achieving high productivity through optimized process parameters.
Solution Approach 2:
The second distillation process continuously operates under controlled conditions (temperature ≤82°C, reflux ratio ≥1.5) to progressively remove impurities including diacetone alcohol, boron compounds, and metal impurities, ensuring complete purification without compromising productivity.
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 produces high-purity IPA with 99.999% purity, containing less than 10 ppm moisture, 50 ppt boron compounds, and 20 ppt metals, reducing defects and improving semiconductor process productivity.
Implementation Method 1
removing diacetone alcohol existing in the isopropyl alcohol through an adsorption process
Implementation Method 2
removing diacetone alcohol, triisopropyl borate (hereinafter also referred to as boron compound) and metal impurities produced as a bottom stream through a distillation process
Data Source
AI summary
In a method for purifying highly pure isopropyl alcohol used in a semiconductor cleaning process, diacetone alcohol present in isopropyl alcohol is removed by an adsorption process, and diacetone alcohol, triisopropyl borate, and metal impurities are removed by a distillation process. The purified isopropyl alcohol may have a purity of has the moisture of 10 ppm or less, the triisopropyl boron compound of 50 ppt or less, and each metal of the metal impurities of 20 ppt or less.