A device for detecting trace amounts of gas in silane gas

Abstract

This utility model relates to an ultra-trace gas detection device in silane gas, comprising a gas concentrator, a gas chromatograph, and a liquid nitrogen tank. The gas concentrator is connected to a main gas pipe, which is connected to five branch pipes: a helium pipe, a first standard gas pipe, a second standard gas pipe, a sample inlet pipe, and a first tail gas pipe. The gas chromatograph is equipped with a PDD detector and is connected to a first carrier gas pipe and a second tail gas pipe. A second carrier gas pipe and a sample pipe are connected between the gas concentrator and the gas chromatograph. A liquid nitrogen inlet pipe is connected between the gas concentrator and the liquid nitrogen tank. This utility model's ultra-trace gas detection device in silane gas has a novel structure and reasonable design, and can analyze phosphine, arsine, and hydrogen sulfide in silane gas at concentrations below 10 pptv. It features safety, high efficiency, stability, and high sensitivity.

Description

Technical Field

[0001] This utility model relates to the field of gas detection technology in the electronics industry, and in particular to an ultra-trace gas detection device for silane gas. Background Technology

[0002] Currently, the silane product standard GB / T 15909-2017 "Gas Silanes for Electronic Industry" specifies the testing of components, moisture and metal content, but does not include the testing of phosphine, arsine and hydrogen sulfide content; while some advanced international semiconductor companies such as TSMC and Yangtze Memory have proposed that the content of phosphine, arsine and hydrogen sulfide in silanes be less than 10 pptv.

[0003] Methods for ultra-trace analysis of gaseous components include gas chromatography-mass spectrometry (GC-MS) and gas chromatography. GC-MS requires equipment costing hundreds of thousands or even millions of dollars, with high subsequent maintenance and operating costs. Gas chromatography is further classified based on detector performance into helium ionization gas chromatography (PDD), flame ionization gas chromatography (FID), flame photometric gas chromatography (FPD), and conductivity detection gas chromatography (TCD). Both flame ionization gas chromatography (FID) and flame photometric gas chromatography (FPD) cannot detect the content of phosphine, arsine, and hydrogen sulfide. While helium ionization gas chromatography (PDD) (detection limit 10 ppbv) and conductivity detection gas chromatography (TCD) (detection limit 100 ppmv) can detect phosphine, arsine, and hydrogen sulfide, their detection limits are far from meeting the requirements of semiconductor customers for these substances. Furthermore, silanes, being a flammable gas in the electronics industry, cannot be safely detected using traditional gas chromatography methods. Utility Model Content

[0004] In view of this, the purpose of this utility model is to provide an ultra-trace gas detection device for silane gas, which can analyze phosphine, arsine and hydrogen sulfide in silane gas with a content of less than 10 pptv, and has the characteristics of safety, high efficiency, stability and high sensitivity.

[0005] This utility model is implemented using the following scheme: a device for detecting trace gases in silane gas, comprising a gas concentrator, a gas chromatograph, and a liquid nitrogen tank. The gas concentrator is connected to a main gas pipe, which is connected to five branch pipes, namely a helium pipe, a first standard gas pipe, a second standard gas pipe, a sample inlet pipe, and a first tail gas pipe. The gas chromatograph is equipped with a PDD detector and is connected to a first carrier gas pipe and a second tail gas pipe. A second carrier gas pipe and a sample pipe are connected between the gas concentrator and the gas chromatograph. A liquid nitrogen inlet pipe is connected between the gas concentrator and the liquid nitrogen tank.

[0006] Furthermore, the second tail gas pipe is connected to the sample outlet and tail gas outlet of the gas chromatograph via tail gas branch pipe A and tail gas branch pipe B, respectively. A vacuum tube is connected to the side of tail gas branch pipe A, and the vacuum tube is connected to a vacuum pump.

[0007] Furthermore, diaphragm valves are respectively installed on the main gas pipe, helium gas pipe, first standard gas pipe, second standard gas pipe, sample inlet pipe, first tail gas pipe, liquid nitrogen inlet pipe, tail gas branch pipe A, tail gas branch pipe B and vacuum pipe.

[0008] Furthermore, a one-way valve is provided on both the helium gas pipe and the first tail gas pipe.

[0009] Furthermore, the main gas pipe is equipped with a high-pressure gauge, a pressure-reducing valve, and a low-pressure gauge.

[0010] Furthermore, the gas chromatograph is connected to a drive gas tube.

[0011] Compared with the prior art, the present invention has the following advantages: The ultra-trace gas detection device in silane gas of the present invention has a novel structure, reasonable design, and low investment cost. It can analyze phosphine, arsine and hydrogen sulfide in silane gas with a content of less than 10 pptv and has the characteristics of safety, high efficiency, stability and high sensitivity.

[0012] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below through specific embodiments and related drawings. Attached Figure Description

[0013] Figure 1 This is a pipeline diagram of the ultra-trace gas detection device according to an embodiment of this utility model;

[0014] Figure 2 This is a gas chromatograph piping diagram according to an embodiment of this utility model;

[0015] The numbers in the diagram are as follows: 1-Gas concentrator, 2-Gas chromatograph, 3-Liquid nitrogen tank, 4-Vacuum pump, 5-Diaphragm valve, 6-Check valve, 7-High pressure gauge, 8-Pressure reducing valve, 9-Low pressure gauge. Detailed Implementation

[0016] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0017] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0018] like Figures 1-2 As shown, a device for detecting trace gases in silane gas includes a gas concentrator 1, a gas chromatograph 2, and a liquid nitrogen tank 3. The gas concentrator is connected to a main gas pipe, which has five branch pipes: a helium pipe, a first standard gas pipe, a second standard gas pipe, a sample inlet pipe, and a first tail gas pipe. The gas chromatograph is equipped with a PDD detector and is connected to a first carrier gas pipe and a second tail gas pipe. A second carrier gas pipe and a sample pipe are connected between the gas concentrator and the gas chromatograph. A liquid nitrogen inlet pipe is connected between the gas concentrator and the liquid nitrogen tank. This invention provides a safe, efficient, stable, and highly sensitive detection device for analyzing phosphine, arsine, and hydrogen sulfide in silane gas at concentrations below 10 pptv.

[0019] The testing equipment and production workshop are connected using EP tubes. Since the boiling points of silane, phosphine, arsine, and hydrogen sulfide are -111.9℃, -87.5℃, -62℃, and -60.4℃, the cooling temperature during concentration is controlled at -95℃ using a gas concentrator, thereby separating and concentrating silane and phosphine, and arsine and hydrogen sulfide.

[0020] Phosphine, arsine, and hydrogen sulfide in the sample were concentrated in an enrichment tube using a gas concentrator, while the remaining silane gas was vented directly. After enrichment, the enrichment tube was placed in a desorption cell to desorb the gas, which was then analyzed by a gas chromatograph equipped with a PDD detector to determine the presence of phosphine, arsine, and hydrogen sulfide.

[0021] The gas concentrator 1 and gas chromatograph 2 (model LX3200) mentioned above are both existing technologies and can be purchased directly from the market. Their principles and structures will not be described in detail here. Figure 2 This is a diagram of the internal piping of Gas Chromatograph 2 (GC2), manufactured by Langxi Instruments (Shanghai) Co., Ltd. GC2 has a sample inlet, sample outlet, split outlet, purifier inlet, purifier outlet, helium inlet, and tail gas outlet. The purifier inlet and outlet are connected to the purifier. The helium inlet is connected to the gas concentrator via a second carrier gas tube, and the first carrier gas tube connects to the purifier and purifier outlet.

[0022] In this embodiment, the second tail gas pipe is connected to the sample outlet and tail gas outlet of the gas chromatograph via tail gas branch pipe A and tail gas branch pipe B, respectively. A vacuum tube is connected to tail gas branch pipe A, and the vacuum tube is connected to vacuum pump 4. The maximum vacuum degree of the vacuum pump is -30Psi. The helium gas used for replacement and cleaning, as well as the carrier gas, are both high-purity helium.

[0023] The gas concentrator's temperature control module regulates the liquid nitrogen volume, concentrating phosphine, arsine, and hydrogen sulfide impurities in silane gas into an enrichment tube. The sample is then desorbed into the gas chromatograph via a desorption cell, significantly improving the sensitivity for phosphine, arsine, and hydrogen sulfide detection. The gas chromatograph, equipped with a PDD detector and corresponding columns suitable for phosphine, arsine, and hydrogen sulfide analysis, enables the detection of trace amounts of these substances in silane. The center-cut method utilizes the different partition coefficients of silane, phosphine, arsine, and hydrogen sulfide within the column. By controlling the valve cut-off time, phosphine, arsine, and hydrogen sulfide are introduced into the detector while silane is vented, thus preventing detector contamination by silane.

[0024] The general process is as follows:

[0025] 1. Use evacuation and vacuuming pipelines to replace and clean the testing equipment and corresponding sample pipelines.

[0026] 2. The gas concentrator controls the cooling chamber temperature to reach -95℃;

[0027] 3. Pass the silane sample from the production workshop into the testing equipment, and after replacement, pass it into the gas concentrator.

[0028] 4. The gas concentrator concentrates phosphine, arsine, and hydrogen sulfide in silane gas through pre-blowing, sample concentration, and sample desorption. The remaining silane gas is directly discharged from the concentrator's tail gas to the tail gas main pipe. At the same time, the desorbed phosphine, arsine, and hydrogen sulfide are introduced into the gas chromatograph.

[0029] 4. After concentration and desorption in the gas chromatograph, the sample is passed through the chromatographic column. Taking advantage of the difference in adsorption capacity of different substances in the stationary and mobile phases of the column, the phosphine, arsine and hydrogen sulfide components are introduced into the chromatographic column for further separation and then reach the PDD detector to form corresponding signal values.

[0030] In this embodiment, diaphragm valves 5 are respectively provided on the main gas pipe, helium gas pipe, first standard gas pipe, second standard gas pipe, sample inlet pipe, first tail gas pipe, liquid nitrogen inlet pipe, tail gas branch pipe A, tail gas branch pipe B and vacuum pipe.

[0031] In this embodiment, one-way valves 6 are respectively provided on the helium pipe and the first tail gas pipe.

[0032] In this embodiment, the main air pipe is equipped with a high-pressure gauge 7, a pressure-reducing valve 8, and a low-pressure gauge 9. The use of EP tubing, VCR connectors, diaphragm valves, pressure gauges, and pressure-reducing valves ensures the airtightness and operational safety of the entire system.

[0033] In this embodiment, the gas chromatograph is connected to a driving gas tube, which is used to provide driving gas to the gas chromatograph to control the operation of the gas chromatograph.

[0034] The specific implementation method is as follows:

[0035] 1. Turn on the helium and driving gas of the gas chromatograph and gas concentrator respectively; then turn on the gas chromatograph and gas concentrator and preheat for more than half an hour.

[0036] 2. Pour liquid nitrogen into the gas concentrator. The gas concentrator is set to -100℃. If the temperature does not meet the requirements, the gas concentrator will automatically replenish the liquid nitrogen. Once the temperature meets the requirements, the replenishment of liquid nitrogen will stop.

[0037] 3. Pass silane into the gas concentrator. After confirming that the gas chromatograph and gas concentrator are in normal working order, click "Start Analysis" on the gas concentrator.

[0038] 4. Press the "Start" button on the gas concentrator to initiate the automatic analysis process of carrier gas pre-purging – sample concentration – sample desorption – carrier gas purging. Carrier gas pre-purging is the process of purging the tubing before sample injection. Sample concentration involves introducing 10L of silane sample through an MFC flow meter at -95℃ to concentrate the phosphine, arsine, and hydrogen sulfide in the silane sample into the enrichment tube. Since the temperature is insufficient for liquefaction, the silane gas is directly discharged through the tail gas pipe. However, once the sample reaches 10L, concentration is stopped and sample desorption is performed, i.e., the liquid sample is vaporized in the desorption cell. During this step, the "Start Analysis" button of the gas chromatograph is automatically triggered, and chromatographic analysis begins. Carrier gas purging is the process of purging and replacing the concentrator after analysis.

[0039] 5. When the sample is desorbed, the gas chromatograph automatically starts the injection analysis and analyzes the sample according to the preset detector temperature, column temperature and valve cut-off time.

[0040] 6. The exhaust gas from the gas concentrator is discharged to the exhaust manifold through the exhaust port of the gas concentrator, and the exhaust gas from the gas chromatograph is discharged to the exhaust manifold through the exhaust outlet of the gas chromatograph.

[0041] 7. Using the same bottle of standard gas, detection was performed before and after enrichment. Comparing the results before and after enrichment, the peak shape was significantly larger and the detection limit was also higher after enrichment. See the table below for details:

[0042] Results of pre-enrichment analysis:

[0043]

[0044] Post-enrichment analysis results:

[0045]

[0046] Unless otherwise stated, if any of the technical solutions disclosed in this utility model discloses a numerical range, then the disclosed numerical range is a preferred numerical range. Any person skilled in the art should understand that the preferred numerical range is merely one among many feasible numerical values ​​that has a more obvious or representative technical effect. Because there are many numerical values, it is impossible to list them all. Therefore, this utility model discloses only some numerical values ​​to illustrate the technical solutions of this utility model. Furthermore, the numerical values ​​listed above should not constitute a limitation on the scope of protection of this utility model.

[0047] If this utility model discloses or relates to mutually fixedly connected parts or structural components, then unless otherwise stated, a fixed connection can be understood as: a detachable fixed connection (e.g., using bolts or screws), or a non-detachable fixed connection (e.g., riveting, welding). Of course, mutually fixed connections can also be replaced by an integral structure (e.g., manufactured by integral molding using a casting process) (except where it is obviously impossible to use an integral molding process).

[0048] In addition, unless otherwise stated, the terms used in any of the technical solutions disclosed in this utility model to indicate positional relationships or shapes include states or shapes that are similar to, close to, or approximate with those states or shapes.

[0049] Any component provided by this utility model can be assembled from multiple individual components, or it can be a single component manufactured by a one-piece molding process.

[0050] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model in any other way. Any person skilled in the art may make changes or modifications to the disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this utility model without departing from its technical solution shall still fall within the protection scope of this utility model.

Claims

1. A device for detecting trace amounts of gas in silane gas, characterized in that: The system includes a gas concentrator, a gas chromatograph, and a liquid nitrogen tank. The gas concentrator is connected to a main gas pipe, which is connected to five branch pipes: a helium pipe, a first standard gas pipe, a second standard gas pipe, a sample inlet pipe, and a first tail gas pipe. The gas chromatograph is equipped with a PDD detector and is connected to a first carrier gas pipe and a second tail gas pipe. A second carrier gas pipe and a sample pipe are connected between the gas concentrator and the gas chromatograph. A liquid nitrogen inlet pipe is connected between the gas concentrator and the liquid nitrogen tank.

2. The ultra-trace gas detection device in silane gas according to claim 1, characterized in that: The second tail gas pipe is connected to the sample outlet and tail gas outlet of the gas chromatograph via tail gas branch pipe A and tail gas branch pipe B, respectively. A vacuum tube is connected to the side of tail gas branch pipe A, and the vacuum tube is connected to a vacuum pump.

3. The ultra-trace gas detection device in silane gas according to claim 2, characterized in that: The main gas pipe, helium gas pipe, first standard gas pipe, second standard gas pipe, sample inlet pipe, first tail gas pipe, liquid nitrogen inlet pipe, tail gas branch pipe A, tail gas branch pipe B and vacuum pipe are each equipped with a diaphragm valve.

4. The ultra-trace gas detection device in silane gas according to claim 2 or 3, characterized in that: One-way valves are respectively installed on the helium gas pipe and the first tail gas pipe.

5. The ultra-trace gas detection device in silane gas according to claim 1, characterized in that: The main air pipe is equipped with a high-pressure gauge, a pressure-reducing valve, and a low-pressure gauge.

6. The ultra-trace gas detection device in silane gas according to claim 1, characterized in that: The gas chromatograph is connected to a drive gas tube.

Images