TW201326811A - Quantitative analytical method of phosphine gas using photocatalytic technique - Google Patents

Abstract

The present invention discloses a quantitative analytical method of phosphine gas using photocatalytic technique. The phosphine gas continuously passes through a photocatalyst and is exposed to UV/visible light for the photocatalytic degradation of the phosphine gas, then the photocatalytic oxidized products of the phosphine gas on the surface of the photocatalyst are analyzed by an ionic chromatography (IC), an atomic absorption spectrophotometer (AAS), an inductively coupled plasma atomic emission spectroscopy (ICP-AES), or an inductively coupled plasma mass spectrometer (ICP-MS). Afterwards, a calibration curve is prepared from analytical data to develop a simple quantitative method of a low concentration phosphine gas. The present invention provides a simple and fast quantitative analytical method, thereby solving the problem of analyzing a low concentration phosphine gas.

Description

Quantitative analysis method of phosphine gas using photocatalysis technology

The invention relates to a quantitative analysis method of phosphine gas, in particular to a quantitative analysis method of phosphine gas using photocatalysis technology.

In the semiconductor process, Phosphine (PH ₃ ) is an important reactive gas, which is commonly used in doping, ion implantation and chemical vapor deposition (CVD) of n-type semiconductors. ) and so on. However, phosphine often causes leaks in clean rooms, which are quite harmful to the human respiratory tract and the surface of the wafer. At present, the analysis of phosphine is generally measured by the reaction of chemical reagents, or by chromatographic analysis, but the above two are only suitable for measuring high concentration of phosphating. hydrogen.

As technology advances, the 28nm process wafers have matured. Since the 28nm process is extremely sensitive to low concentrations of phosphine, the range of concentrations that can be measured by existing prior art is no longer applicable. . In order to improve the yield and productivity of semiconductor processes and reduce the impact on the health of operators, the current industry is to measure the low concentration of phosphine in the environment by placing clean wafers in the environment 24-48. After an hour, the surface of the wafer is converted to phosphoric acid by the reaction of phosphine with water molecules, and is etched on the surface to cause defects, and then the wafer is observed by Scanning Electron Microscope (SEM). Surface, and determine the relative concentration of phosphine in the environment by the area of the defect etched on the surface of the wafer to increase the indoor air exchange rate or other regulation, thereby reducing the concentration of phosphine in the environment to avoid wafer formation. The hazard and reduce the chance of defects on the wafer surface. Since the analysis time required for the foregoing analysis method is lengthy, the yield and productivity of the semiconductor process cannot be effectively improved.

Therefore, there is still a need to provide a quantitative analysis method of phosphine gas which can utilize photocatalytic technology to increase the analysis speed to solve the problems of the prior art.

In view of this, the present invention provides a quantitative analysis method of phosphine gas using a photocatalytic technique to solve the problem of tedious analysis time existing in the prior art.

The main object of the present invention is to provide a method for quantitatively analyzing phosphine gas by using a photocatalytic technique, which can continuously increase the speed of analysis by introducing a phosphine gas into a photocatalyst irradiated by ultraviolet light/visible light for photocatalytic degradation reaction. Then, Ion Chromatograph (IC), Atomic Absorption Spectrophotometer (AAS), Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) or inductively coupled plasma An inductively Coupled Plasma Mass Spectrometer (ICP-MS) is used to analyze the photocatalytic oxidation product of phosphine on the surface of the photocatalyst, and a calibration curve is prepared by using the analytical data to develop a low concentration phosphine gas. Simple quantitative method.

In order to achieve the foregoing object of the present invention, the present invention provides a quantitative analysis method of phosphine gas using a photocatalytic technique, which comprises: preparing a series of known concentrations of phosphine gas, and separately photocatalyzing using a photocatalyst surface Decomposing the respective known concentrations of phosphine gas in the series to generate respective reactants on the surface of the photocatalyst, and washing the respective reactants with ultrapure water to recover the ultrapure water; The content or signal value of the reactant in the ultrapure water; preparing a calibration curve by correlating the known concentration of the phosphine gas with the content or signal value of the corresponding reactant; and using the photocatalyst surface photocatalysis Decomposing an actual sample of an unknown concentration of phosphine gas, and correspondingly generating a reactant of the actual sample on the surface of the photocatalyst, and washing the reactant of the actual sample with ultrapure water to recover the ultrapure water, and then analyzing the super The content or signal value of the reactant of the actual sample in pure water, and the concentration of the actual sample is estimated based on the calibration curve.

In one embodiment of the invention, the reactants are present in a concentration ranging from 10 ppm to 5 ppb.

In an embodiment of the invention, the step of formulating a series of known concentrations of phosphine gas is: using a mass flow controller to formulate a standard concentration of phosphine gas into a series of known concentrations. Phosphine gas.

In an embodiment of the invention, the step of estimating the concentration of the actual sample further comprises: setting a series of phosphine gas of the same standard concentration, and performing photocatalytic reaction on the photocatalyst surface with different cumulative reaction times respectively. And preparing a calibration curve, wherein one calibration axis of the calibration curve is the removal amount of the phosphine gas under different cumulative reaction time, and the other coordinate axis is a reactant generated by the photocatalytic reaction of the phosphine gas. content.

In an embodiment of the invention, the amount of the phosphine gas removed is analyzed by at least one instrument to determine the concentration of the phosphine gas passing through the surface of the photocatalyst after the photocatalytic reaction, and the phosphine gas before the reaction. The concentrations are compared and known by calculation.

In an embodiment of the invention, the instrument is a Fourier Transform Infrared Spectroscopy (FTIR).

In an embodiment of the invention, the material of the photocatalyst surface is selected from the group consisting of titanium dioxide, zinc oxide, tin dioxide or cadmium sulfide.

In one embodiment of the invention, the step of analyzing the amount or signal value of the reactants in each ultrapure water is performed using an ion chromatograph (Ion Chromatograph, IC) to analyze the phosphate in the reactants.

In an embodiment of the invention, the step of analyzing the content or signal value of the reactants in the respective ultrapure water is performed by using an Atomic Absorption Spectrophotometer (AAS) or an inductively coupled plasma atomic emission spectrometer (Inductively Coupled). Plasma Atomic Emission Spectroscopy (ICP-AES), Inductively Coupled Plasma Mass Spectrometer (ICP-MS), or a combination thereof, to analyze phosphorus atoms in the reactants.

In one embodiment of the invention, the step of photocatalyzing the actual sample of an unknown concentration of phosphine gas using the photocatalyst surface is performed in a semiconductor process clean room.

The present invention has significant advantages and advantageous effects over conventional techniques. According to the above technical solution, the method for quantitatively analyzing phosphine gas using the photocatalytic technology of the present invention has at least the following advantages and beneficial effects: the present invention utilizes a photodegradation reaction to decompose phosphine gas into phosphine. The photocatalytic oxidation product is further washed with ultrapure water to recover the ultrapure water, and then the oxidation product dissolved in the ultrapure water is analyzed by a conventional technique to establish a calibration curve, which can be applied to Analysis of low concentrations of phosphine gas. In addition to the simple and rapid quantitative analysis, the present invention can accurately quantify the concentration of low-concentration phosphine gas, thereby solving the problem of the existing low-concentration phosphine gas analysis.

In order to further illustrate the technical means and efficacy of the present invention for achieving the purpose of the present invention, the specific method of quantitative analysis of phosphine gas using photocatalytic technology according to the present invention will be described below with reference to the accompanying drawings and preferred embodiments. The embodiments, features, and effects are described in detail below.

The invention discloses a quantitative analysis method of phosphine gas by using a photocatalytic technology, which is characterized in that a phosphine gas is continuously introduced into a photocatalytic degradation reaction by a photocatalyst irradiated by ultraviolet light/visible light, and the photocatalyst is washed in ultrapure water. After the surface is recovered, the ultrapure water is recovered, followed by an ion chromatograph (IC), an atomic absorption spectrophotometer (AAS), and an inductively coupled plasma Atomic Emission Spectroscopy (ICP). -AES) or Inductively Coupled Plasma Mass Spectrometer (ICP-MS) to analyze the photocatalytic oxidation product of phosphine dissolved in ultrapure water, and prepare a test by using the analytical data. The present invention is applicable to the analysis of low concentrations of phosphine gas, which is in the range of between 10 ppm and 5 ppb.

The following is a flow chart of the steps of the quantitative analysis method of the phosphine gas using the photocatalytic technique according to the first embodiment, which comprises:

Step S11, photocatalyzing the phosphine gas, and washing the corresponding reactants on the surface of the photocatalyst with ultrapure water, and recovering the ultrapure water;

Step S12, analyzing the reactant dissolved in the ultrapure water by using an instrument;

Step S13, preparing a calibration curve by using the foregoing analysis data;

In step S14, the actual sample of the phosphine gas of unknown concentration is decomposed by the photocatalytic reaction, and after the water is washed, the reactant is analyzed by an instrument, and then the concentration of the actual sample is calculated according to the calibration curve.

In the above step S11, the photocatalyst comprises titanium dioxide, zinc oxide, tin dioxide, and cadmium sulfide.

In the above step S12, the instrument comprises an ion chromatograph (IC), an atomic absorption spectrophotometer (AAS), and an inductively coupled plasma Atomic Emission Spectroscopy (ICP-AES). ), Inductively Coupled Plasma Mass Spectrometer (ICP-MS). In the above IC, the phosphate in the reactant is analyzed; in AAS, ICP-AES, and ICP-MS, the phosphorus atom in the reactant is analyzed.

[Example 1]

In one embodiment of the present invention, a Fourier Transform Infrared Spectroscopy (FTIR) is firstly used to quantify the concentration of phosphine gas to 0.5 ppm, and then separately prepared by a mass flow controller. Concentration of phosphine gas at a concentration of 0.4 ppm, 0.3 ppm, 0.2 ppm, 0.1 ppm. Then, according to the order of low concentration to high concentration, the phosphine gas is continuously introduced into the reaction system of the second figure, and the photocatalytic reaction is carried out, wherein the photocatalytic reaction system needs to degrade 98% or more of the phosphine gas, It is ensured that the introduced phosphine gas can be converted into phosphorus oxide and deposited (accumulated) on the surface of the titanium dioxide. The photocatalytic reaction steps are as follows:

(1) Using air to vent the entire reaction unit for about 30 minutes, so that the entire reaction system is filled with air;

(2) Adjust the FTIR to the measurement background mode to test the general air as the background value and record the background value;

(3) Turn on the UVA light source to adjust the light intensity to 2-3 mW/cm ² ;

(4) After adjusting the phosphine and air flow controller to an appropriate value, mix it into the pre-test line to fill the FTIR Gas-Cell with the mixed gas;

(5) Wait until the phosphine concentration has stabilized during the pre-test, place the prepared sample in the reactor, and then adjust the line to pass it into the reactor;

(6) Under the dark adsorption, the first take time is 3 minutes, then take one point every 1 minute, take a total of 5 times, and finally turn on the light source when the dark adsorption reaches equilibrium;

(7) Turn on the light source to photocatalyticly react a known concentration of phosphine gas;

(8) After the end of the experiment, the pipeline must be adjusted to the pre-test, and the phosphine gas contained in the pipeline should be removed by air to carry out the photocatalytic reaction of the next concentration of phosphine gas.

Then, the titanium dioxide samples subjected to the respective concentrations of phosphine are respectively immersed in 50 ml of ultrapure water and stirred for one hour, and filtered by a filter paper, and the filtrate is shaken by an ultrasonic oscillator for 5 minutes to induce Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) was used to detect the phosphorus atom content in the filtrate. Finally, the relationship between the Moiré number of the dephosphorized phosphine gas and the Moir number of the phosphorus atom detected on the surface of the titanium dioxide sample is prepared as a calibration curve, as shown in the third figure.

The air sampler is used to take the air in the clean room, and the photocatalytic reaction described above is used to decompose the actual sample of the unknown concentration of the phosphine gas, and the titanium dioxide sample after the reaction of the unknown concentration of the phosphine gas is soaked. Stir in 50 ml of ultrapure water for one hour, and after filtering, the filtrate was shaken for 5 minutes with a ultrasonic oscillating machine, and then the phosphorus atom content in the filtrate was detected by ICP-AES, and the reaction was reversed according to the calibration curve. The amount of phosphine removed in the gas phase, and when the design conversion rate is 98% or more, the value of the phosphorus atom contained in the aqueous solution can be reversed to know the actual phosphine in the air. The concentration of the gas.

As described above, the present invention is a method for quantitatively analyzing a phosphine gas using a photocatalytic technique, which is a photocatalytic oxidation product in which a phosphine gas is decomposed into a phosphine by a photodegradation reaction, and then the oxidation product is analyzed by an instrument. Thereby, a calibration curve is established, which can be applied to the analysis of low concentration phosphine gas. It can be known from the R square value of the above embodiment that the invention has good accuracy, and the quantitative analysis of low concentration phosphine gas can be performed simply and quickly, thereby solving the problem of the existing low concentration phosphine gas analysis. .

While the invention has been described above in terms of the preferred embodiments, the invention is not intended to limit the invention, and the invention may be practiced without departing from the spirit and scope of the invention. The scope of protection of the present invention is therefore defined by the scope of the appended claims.

S11-S14. . . step

The first figure is a flow chart of the steps of the quantitative analysis method of phosphine gas using photocatalysis technology of the present invention.

The second figure is a reaction system of an embodiment of the method for quantitatively analyzing phosphine gas using photocatalysis technology of the present invention.

The third figure is a calibration curve of an embodiment of the method for quantitatively analyzing phosphine gas using photocatalysis technology of the present invention.

S11-S14. . . step

Claims (10)

A method for quantitatively analyzing phosphine gas using photocatalytic technology, comprising: preparing a series of known concentrations of phosphine gas, and utilizing a photocatalyst surface to photocatalyticly decompose the respective known concentrations of phosphating of the series Hydrogen gas to generate respective reactants on the surface of the photocatalyst, and the respective reactants are washed with ultrapure water to recover the ultrapure water; and the content or signal of the reactants in each ultrapure water is analyzed. a relationship between a known concentration of phosphine gas and a corresponding reactant content or signal value to prepare a calibration line; and photocatalytic decomposition of an unknown concentration of phosphine gas using the photocatalyst surface Actual sample, and correspondingly generating a reactant of the actual sample on the surface of the photocatalyst, and then the reactant of the actual sample is washed with ultrapure water to recover the ultrapure water, and then the reactant of the actual sample in the ultrapure water is analyzed. The content or signal value, and the concentration of the actual sample is estimated based on the calibration curve. A method for quantitatively analyzing a phosphine gas using a photocatalytic technique as described in claim 1, wherein the content of the reactant is in a concentration ranging from 10 ppm to 5 ppb. A method for quantitatively analyzing a phosphine gas using a photocatalytic technique as described in claim 1, wherein the step of preparing a series of known concentrations of phosphine gas is: using a mass flow controller to measure the standard concentration The phosphine gas is formulated into a series of known concentrations of phosphine gas. The method for quantitatively analyzing phosphine gas using photocatalytic technology according to claim 1, wherein the step of estimating the concentration of the actual sample further comprises: setting a series of phosphine gas of the same standard concentration, and then separately A calibration curve is prepared by performing a photocatalytic reaction on the photocatalyst surface with different cumulative reaction times, wherein one calibration axis of the calibration curve is the removal amount of phosphine gas with different cumulative reaction time, and the other coordinate axis is The content of the reactant formed by the photocatalytic reaction of the phosphine gas. A method for quantitatively analyzing a phosphine gas using a photocatalytic technique according to the fourth aspect of the invention, wherein the phosphine gas is removed by at least one instrument to analyze the phosphating of the surface of the photocatalyst after the photocatalytic reaction. The concentration of the hydrogen gas is compared with the concentration of the phosphine gas before the reaction and is known by calculation. A method for quantitatively analyzing a phosphine gas using a photocatalytic technique as described in claim 5, wherein the apparatus is a Fourier transform infrared spectrometer. The method for quantitatively analyzing phosphine gas using photocatalytic technology according to claim 1, wherein the material of the photocatalyst surface is selected from the group consisting of titanium dioxide, zinc oxide, tin dioxide or cadmium sulfide. The method for quantitatively analyzing phosphine gas using photocatalytic technology as described in claim 1, wherein the step of analyzing the content or signal value of the reactants in each ultrapure water is analyzed by using an ion chromatograph. Phosphate in the reaction. A method for quantitatively analyzing a phosphine gas using a photocatalytic technique as described in claim 1, wherein the step of analyzing the content or signal value of the reactants in each ultrapure water is performed by using an atomic absorption spectrometer, inductive coupling A plasma atomic emission spectrometer, an inductively coupled plasma mass spectrometer, or the like, is used to analyze the phosphorus atoms in the reactants. A method for quantitatively analyzing a phosphine gas using a photocatalytic technique as described in claim 1, wherein the photocatalytic surface is used to photocatalyticly decompose an actual sample of an unknown concentration of phosphine gas, in a semiconductor The process is carried out in a clean room.