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Trace Analysis of Bulk Electronic Gas Using a Newly Designed Ion Mobility Spectrometer

IP.com Disclosure Number: IPCOM000019405D
Publication Date: 2003-Sep-12
Document File: 2 page(s) / 145K

Publishing Venue

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Abstract

An atmospheric pressure ionization mass spectrometer (APIMS) is the only analytical technique that provides an accurate measurement of trace impurities in electronic bulk gases at levels below 1 part per billion (ppb). Recently, it has been shown that an ion mobility spectrometer (IMS) is capable of determining the amount of trace impurities at levels below 1 ppb. PCP is a manufacturer of the IMS. The IMS is potentially an alternative technique to the APIMS. The advantages of the IMS over the APIMS are the cost and simplicity of the instrument. The cost of the IMS could possibly be a third of the APIMS. The IMS operates at atmospheric pressure and does not require any vacuum components. This makes the IMS more rugged than the APIMS. The IMS instrument for this application is not yet commercially available. To the best of our knowledge, some IMS manufactures are developing the IMS instrument for trace analysis of bulk gases. We anticipate that the IMS instrument will be commercially available by 2001.

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Trace Analysis of Bulk Electronic Gas Using a Newly Designed Ion Mobility Spectrometer

I. BACKGROUND

An atmospheric pressure ionization mass spectrometer (APIMS) is the only analytical technique that provides an accurate measurement of trace impurities in electronic bulk gases at levels below 1 part per billion (ppb). Recently, it has been shown that an ion mobility spectrometer (IMS) is capable of determining the amount of trace impurities at levels below 1 ppb. PCP is a manufacturer of the IMS. The IMS is potentially an alternative technique to the APIMS. The advantages of the IMS over the APIMS are the cost and simplicity of the instrument. The cost of the IMS could possibly be a third of the APIMS. The IMS operates at atmospheric pressure and does not require any vacuum components. This makes the IMS more rugged than the APIMS. The IMS instrument for this application is not yet commercially available. To the best of our knowledge, some IMS manufactures are developing the IMS instrument for trace analysis of bulk gases. We anticipate that the IMS instrument will be commercially available by 2001.

Moisture background and resolution of the drift time are challenging issue in the development of the IMS for trace impurity analysis. Our invention is focused on the reduction of the moisture background. The IMS is generally composed of the drift cell or gas cell and electronic components. The drift cell is normally not gas tight and the electronic components normally exposed to the test gas. Therefore, diffusion of gas molecules between the drift cell and the electronic components is inevitable. The gas diffusion does not have any significant effect when the IMS is used to analyze impurities in the parts per million (ppm) range. The electronic components, such as resistors and transistors, can absorb and desorb chemicals, especially moisture, from the surrounding environment. Therefore, it is difficult to lower the background level of moisture, due to outgassing from the electronic components. For the analysis of bulk electronic gases, the moisture background should be below 0.1 ppb. In an effort to reduce the moisture background, we propose a...