Germane Purification via Molecular Sieve Adsorption
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Solution Overview
Problem
The semiconductor industry faces challenges in producing high purity germane gas due to contamination from phosphine, which is difficult to separate from germane due to their similar volatility and molecular weight, leading to impurity levels exceeding 50 ppb, causing defects and yield reductions in semiconductor manufacturing.
Innovation Solution
A process using a molecular sieve with an effective pore diameter of 4 to 5 Angstroms selectively removes phosphine from germane gas by adsorbing phosphine preferentially, with the sieve being conditioned with germane and heated to prevent overheating, allowing for effective purification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional separation methods are used to separate phosphine from germane, then the process is simple, but the phosphine removal efficiency is insufficient (cannot reduce to below 50 ppb)
Solution Approach 1:
The patent employs a molecular sieve with controlled pore size (3-4 Angstroms) that selectively adsorbs phosphine molecules while allowing germane molecules to pass through. The porous structure of the molecular sieve enables size-selective separation based on the slight difference in molecular dimensions between phosphine and germane, achieving high purity germane production without complex multi-stage separation systems.
2Manufacturing precision
If molecular sieve is used to adsorb phosphine, then phosphine removal efficiency improves, but the molecular sieve may overheat and decompose germane
Solution Approach 1:
The patent introduces a heat exchange medium (such as a heat exchanger or thermal coupling system) between the molecular sieve bed and the incoming germane gas stream. This intermediary system transfers heat from the exothermic adsorption process to the incoming gas, preventing temperature buildup in the molecular sieve while maintaining continuous phosphine removal efficiency.
Solution Approach 2:
The patent implements temperature monitoring and control mechanisms that detect when the molecular sieve approaches its temperature threshold. When temperature becomes excessive, the system adjusts operational parameters such as reducing gas flow rate, increasing cooling intensity, or switching to a fresh molecular sieve bed, thereby preventing germane decomposition while maintaining optimal phosphine removal performance.
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 process achieves phosphine levels below 50 ppb in germane gas, improving the purity and reducing defects in semiconductor manufacturing by effectively separating phosphine from germane, as demonstrated by gas chromatographic analysis.
Implementation Method 1
phosphine, a compound with similar volatility and molecular size as germane may be selectively removed from a germane gas containing phosphine by a properly conditioned molecular sieve having an effective pore diameter of about 4 Angstroms or greater. Phosphine is retained by the molecular sieve in preference to germane.
Data Source
AI summary
A process and system for the purification of germane containing phosphine to provide a purified germane product. One aspect of the present invention is a process for making a purified germane product containing less than 50 ppb of phosphine which comprises providing a phosphine contaminated germane gas hydrogen gas mixture; passing the germane gas hydrogen gas mixture through an adsorbent which selectively adsorbs phosphine and withdrawing therefrom a purified germane gas hydrogen mixture; and separating the purified germane gas from the hydrogen germane gas mixture.