This disclosure is related to a calibrated particle analysis apparatus and method.
Specialty gases (such as ammonia, hydrogen chloride, nitrogen trifluoride, carbon tetrafluoride, and etchants) and volatile organic solutions (such as isopropanol, acetone) are widely used in semiconductor processes, such as etching and cleaning processes. With the advancement of semiconductor process technology, from the past 14 nm to the current 7 nm to the future 5 nm process, the critical line width is constantly shrinking. In response to this trend, even a very small amount of pollution (such as particles, aerosols, transition metals, or heavy metals) may cause defects, such as short-circuiting, current leakage and pores. In the trend of decreasing line width of the semiconductor process and in order to maintain high product yield, semiconductor manufacturers need to confirm the particle contamination that may be encountered in each reagent (in electronics grade) used in each process step, and accurately analyzing the particle sizes is important in accurately controlling product yield and improve product quality.
However, the currently used liquid particle counter (LPC) cannot detect particles with a particle size of 20 nm or less. A particle analyzer, such as a scanning mobility particle sizer (SMPS) including a differential mobility analyzer (DMA) and a condensation particle counter (CPC), can detect particles having a particle size of 20 nm or less, but cannot directly analyze particles in volatile organic solutions or Specialty gases, because the volatile organic solutions and the Specialty gases will corrode the parts of the particle analyzer.
However, if the organic solutions and the Specialty gases entraining particles, even a very small amount of particles may fall on the treated surface of the object, and a yield loss is resulted.
Therefore, for a long time, whenever a semiconductor factory finds a yield loss of a product due to unknown reasons, only the replacement of raw materials of different production batches or even the replacement of different raw material suppliers can be relied, and thus batches of products are often scrapped. Hence, how to solve this problem is one of the important issues.
In order to solve the problems above, some embodiments of this disclosure introduces a gas exchange device (GED) for gas exchange before the particle analyzer. The gas exchange device exchanges a special gas or a volatile organic substance in the sample with a carrier gas used by the particle analyzer. At the same time, the particles in the sample can be retained and transported to the particle analyzer for measuring various particle properties.
Accordingly, a calibrated particle analysis apparatus is provided. The calibrated particle analysis apparatus comprises a gas exchange device, a plurality of flow controllers, and a particle analyzer. The gas exchange device has a first end and a second end and includes an inner pipe and an outer pipe sleeving outside the inner pipe. The inner pipe has an inner gas inlet disposed at the first end, an inner gas outlet disposed at the second end, and a porous partition wall made from a porous material having properties of resistant to corrosion, non-reactive and not easily adhered to particles. The inner tube is provided to be an inner gas flow channel for circulation of a sample. The outer pipe has an outer gas inlet adjacent to the second end, an outer gas outlet adjacent to the first end, and an outer pipe wall made from a corrosion resistant material. A space between the inner pipe and the outer pipe is provided to be an outer gas flow channel for circulation of a carrier gas. A first flow controller, a second flow controller, and a third flow controller are respectively coupled to the inner gas inlet, the outer gas inlet, and the outer gas outlet. The particle analyzer coupled to the inner gas outlet for introducing particles in the sample carried by the carrier gas.
Accordingly, a calibrated particle analysis method is also provided. The calibrated particle analysis method uses the calibrated particle analysis apparatus above, and comprises the following steps. First, the first, second, and third flow controllers are closed. The second and third flow controllers are opened, so that the carrier gas is allowed to enter the outer gas flow channel from the outer gas inlet and leave the outer gas flow channel from the outer gas outlet. The first flow controller is opened, so that the sample is allowed to enter the inner gas flow channel from the inner gas inlet and leave the inner gas flow channel from the inner gas outlet, and gases of the sample is allowed to be exchanged with the carrier gas at the same time. Particles in the sample and carried by the carrier gas are introduced into the particle analyzer for performing particle analysis.
In light of the foregoing, a gas exchange device is disposed before the particle analyzer to replace the gas or volatile organic compounds in the sample to be tested by a carrier gas commonly used in particle analyzers. The apparatus and method can not only eliminate the deviation of the obtained analysis result caused by different gases or volatile organic substances in the sample to be tested. If the gas or volatile organic compounds in the sample to be tested are toxic or corrosive, it can also increase the safety of the analytical operation and extend the life of the particle analyzer.
The above described features and advantages of the present disclosure will be more apparent from the following description.
The present disclosure can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:
Please refer to
According to one embodiment, a calibrated particle analysis apparatus 100 has a gas exchange device 200, a first flow controller 310 coupled to the gas exchange device 200, and a second flow controller 320 and a third flow controller 330, and also has a particle analyzer 400 coupled to the gas exchange device 200.
The gas exchange device 200 described above has an inner pipe 210 and an outer pipe 220 that sleeves outside the inner tube 210. The inner gas flow channel 214 formed by the inner tube 210 is used to circulate a sample 110 to be analyzed, and the outer gas flow channel 224 formed by the gap between the inner tube 210 and the outer tube 220 is used to circulate a carrier gas 120.
The inner tube 210 described above is constituted by a porous partition wall 212 and has an inner gas inlet 216 and an inner gas outlet 218. The porous partition wall 212 is made of a material that is resistant to corrosion, non-reactive and not easily adhered by particles. The material may be, for example, polytetrafluoroethylene (PTFE). Moreover, the porous partition wall 212 has a porosity of 50-70% and an a pore diameter of about 200-500 nm for gas exchange.
In order to match the gas exchange capacity of the sample to more than 0.1 L/min and the gas exchange efficiency may reach 99% or more, the inner pipe 210 may have an inner diameter of, for example, 1 to 30 mm, and the inner pipe 210 may have a length of at least 10 cm and can be, for example, 10-300 cm. In addition, the shape of the gas exchange device 200 is not limited to the straight tubular shape shown in
The outer pipe 220 is constituted by an outer pipe wall 222 and has an outer gas inlet 226 and an outer gas outlet 228. The outer pipe wall 224 is made of a corrosion-resistant and air-tight material, such as stainless steel or Telfon, to prevent leakage of toxic or corrosive gases in the inner pipe 210. Further, the inner diameter of the outer pipe 220 is not particularly limited as long as it can accommodate the inner pipe 210.
The first flow controller 310 is coupled to the inner gas inlet 216 to control the gas inflow rate of the sample 110 at the inner gas inlet 216. The above sample 110 contains various common Specialty gases and various volatile liquid raw materials used in the semiconductor factories. The Specialty gases comprise may be, for example, NH3, HCl, NF3, CO2, N2O, BF3, AsH3, PH3, GeH4, CF4, HF, or the like. The above volatile liquid raw materials may be, for example, isopropyl alcohol, some slurries, and hydrogen peroxide.
Therefore, if the sample 110 is a liquid sample, it will pass through a nebulizer (not shown in the figure), and the particles in the liquid sample will form a dry aerosol before passing through the gas pipeline (not shown in the figure) and the first flow controller 310 to be delivered into the inner pipe 210 of the gas exchange device 200.
The second flow controller 320 is coupled to the outer gas inlet 226 to control the gas inflow rate of the carrier gas 120 at the outer gas inlet 226. The carrier gas 120 described above may be, for example, nitrogen or air. The third flow controller 330 is coupled to the outer gas outlet 228 described above, so that the gas outflow rate of the outer gas flow channel 224 can be controlled. Therefore, the second flow controller 320 and the third flow controller 330 cooperate to control the gas flow rate of the outer gas flow channel 224. In addition, after the third flow controller 330, an air pump (not shown) may be configured to increase the exhaust efficiency at the outer gas outlet 228.
The first flow controller 310, the second flow controller 320, and the third flow controller 330 may be independently a mass flow controller, a rotameter, an orifice flow meter, an ultrasonic flowmeter, a flow-limiting valve, a needle valve, or other available flow controllers.
The particle analyzer 400 described above can be used to analyze various properties of particles in a sample, such as particle size, particle concentration, or chemical composition of the particles, and the like. At present, the common particle analyzer 400 has, for example, a scanning mobility particle sizer (SMPS), a condensation particle counter (CPC), an optical particle counter (OPC), an optical particle sizer (OPS), or an aerodynamic particle sizer (APS).
Therefore, a method of using the above-described calibrated particle analysis apparatus 100 is as follows. First, it is made sure that the first flow controller 310, the second flow controller 320, and the third flow controller 330 are closed. Then, the second flow controller 320 and the third flow controller 330 are opened, and the carrier gas 120 enters the outer gas flow channel 224 from the outer gas inlet 226 and exits the outer gas flow channel 224 from the outer gas outlet 228.
Next, the first flow controller 310 is opened to let the sample 110 enter the inner gas flow channel 214 from the inner gas inlet 216 and leave the inner gas flow channel 214 from the inner gas outlet 218. At the same time, the carrier gas 120 will exchange with the gases in the sample 110, and then the mixed gas of gases in the sample 110 and the carrier gas 120 is exhausted from the outer gas outlet 228. The carrier gas 120 then carries the particles from the sample 110 into the particle analyzer 400 for performing analysis.
According to another embodiment, the calibrated particle analysis apparatus 100 may further include a flowmeter 340 disposed between the inner gas outlet 218 and the particle analyzer 400 and coupled to the inner gas outlet 218 and the particle analyzer 400. Therefore, after the carrier gas 120 carries the particles in the sample 110 from the inner gas outlet 218 of the inner gas flow channel 214, the particles and the carrier gas 120 can pass through the flowmeter 340 and then entering the particle analyzer 400 for analysis. The flowmeter 340 is used to monitor the gas inflow rate of the particle analyzer 400. If the gas inflow rate of the particle analyzer 400 is greater than or equal to the gas inflow rate of the sample 110 at the inner gas inlet 216, indicating that the particles in the sample 110 are not lost, all of the particles may enter the particle analyzer 400 for analysis.
According to still another embodiment, the calibrated particle analysis apparatus 100 may further include a nebulizer 132 coupled to an inlet conduit of the particle analyzer 400 through the particle standard inlet 134. The nebulizer 132 is used to generate the particle standard 130 to mix the standard particles having known particle size and concentration in the particle standard 130 with the particles in the sample 110 in the gas pipeline. Then, the mixture is introduced into the particle analyzer 400 to perform analysis by using the standard particles as the internal standard. Commonly used standard particles include polystyrene particles of different particle sizes, for example.
According to still another embodiment, the calibrated particle analysis apparatus 100 may further include a particle capture filter 500. In
After a period of accumulation, the particles left in the particle capture filter 500 can be sampled for other qualitative and quantitative analysis, such as scanning electron microscope (SEM) that can detect particle size, Energy-dispersive X-ray spectroscopy (EDS) that can analyze the particle composition, or inductively coupled plasma mass spectrometry (ICP-MS) that can analyze metal elements.
In order to eliminate the deviation of the analytical results caused by different gases or volatile organic compounds in the sample, and increase the safety of the analysis operation and prolong the service life of the particle analyzer, some examples are given for testing the gas exchange efficiency of the above gas exchange device.
The gas exchange efficiency test uses nitrogen as the carrier gas. The residual concentration of the tested gas after gas exchange by the gas exchange device is detected by Fourier-transformation infrared spectroscopy (FTIR). The calculation formula of gas exchange efficiency E is as follows:
In this experimental example, the flow rate of the gas as the sample was fixed at 1 L/min, and then the flow rate of nitrogen as the carrier gas was changed, and the influence of the ratio of the carrier gas flow rate/sample flow rate on the gas exchange efficiency was tested. In addition, the gas used as sample has NH3, N2O, CO2, NF3, and CF4 to test whether the gas exchange efficiency will vary depending on the various gas. The relevant parameters of the above several gases are listed in Table 1, and the results obtained are shown in
In
In order to ensure the particle loss in the sample when the gas exchange efficiency is 99% or more, an example is given to test the particle transport efficiency of the above gas exchange device. The formula for particle transport efficiency T is as follows:
In this experimental example, the particle size was changed to test its effect on particle transport efficiency. The particles used herein are polystyrene particles with particle sizes of 60 nm, 100 nm, 300 nm, and 500 nm, respectively. Other test conditions are as described above. The sample of the particle transport efficiency test is a carrier gas carrying polystyrene particles with a flow rate of 1 L/min. The carrier gas is nitrogen and has a flow rate of 4 L/min. The results obtained are shown in Table 2. As can be seen from Table 2, the particle transfer efficiency is almost 100%.
From the test results of the above experimental examples, the specifications of the gas exchange device used in the following experimental examples are as follows. The inner pipe is made of porous polytetrafluoroethylene (PTFE) material and the gas exchange devices can handle samples with a flow rate of 1 L/min and the obtained gas exchange efficiency was 99.99% or more. Next, the gas exchange device was placed in a calibrated particle analysis apparatus as shown in
In this example, polystyrene particles with particle sizes of 100 nm and 300 nm were respectively used, and particle analysis results before and after calibration using gas exchange device were compared. The polystyrene particles are transported by argon into the inner pipe of the gas exchange device, and the carrier gas in the outer pipe is nitrogen. The results obtained for the 100 nm and 300 nm polystyrene particles are shown in
The comparison results of 100 nm polystyrene particles are looked at first.
The comparison results of 300 nm polystyrene particles are looked at next.
As shown in
Therefore, between the gas exchange device 200 and the particle analyzer 400, there are two gas passages can be chosen. One is the first path 410, which is only an empty tube to allow the analytical sample to directly enter the particle analyzer 400. The other one is a second path 510 configured with a particle capture filter 500. The analysis sample first passes through the particle capture filter 500 and then enters the particle analyzer 400.
In this example, sample is a mixture of ammonia and particles, and the carrier gas is nitrogen. The analysis results using the above two paths are shown in
As shown in
In this example, the sample is NF3 pure gas with a flow rate of 1 L/min. The carrier gas is nitrogen with a flow rate of 6 L/min. The results of the analysis using the above-mentioned added particle standard are shown in
In order to avoid interference with the sample analysis, polystyrene particles with a particle size of 100 nm may be selected, so that the particle size distribution of the particle standard does not overlap with the particle size distribution of the sample.
In summary, a gas exchange device is disposed before the particle analyzer to replace the gas or volatile organic compounds in the sample with the carrier gas commonly used by the particle analyzer. The apparatus and method can not only eliminate the deviation of the obtained analysis result caused by different gases or volatile organic substances in the sample to be tested. If the gas or volatile organic compounds in the sample to be tested are toxic or corrosive, it can also increase the safety of the analytical operation and extend the life of the particle analyzer.
Although the present disclosure has been disclosed in the above embodiments, it is not intended to limit the present disclosure. Those skilled in the art can make some modifications and refinements without departing from the spirit and scope of the present disclosure. Hence. the scope of the disclosure is defined by the scope of the appended claims.
This application claims the priority benefit of U.S. provisional application Ser. No. 62/618,637, filed on Jan. 18, 2018. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.
Number | Date | Country | |
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62618637 | Jan 2018 | US |