Trace detection method for testing mercury cadmium telluride material by glow discharge mass spectrometer and application

Abstract

The invention discloses a trace detection method for testing a mercury cadmium telluride material by a glow discharge mass spectrometer and application, and belongs to the technical field of analysis and detection. The trace detection method comprises the following steps: placing a tellurium-cadmium-mercury sample on an indium strip, testing by adopting an auxiliary cathode method, and controlling the discharge voltage to be 800-850V, the discharge current to be less than 3.0 mA, the sputtering time to be 40-60 minutes and the loading amount of the sample to be 10-21 mg under a liquid nitrogen cooling condition, thereby realizing ppm-level impurity detection. Through the collaborative design of the indium strip carrier and the auxiliary cathode, in combination with liquid nitrogen cooling and low-power discharge parameters, high-precision and high-stability detection of ppm-level impurities in the HgCdTe material is realized, the long-term technical bottleneck of HgCdTe trace impurity detection in the field of semiconductor materials is directly solved, and a reliable analysis means is provided for improving the yield of an infrared focal plane array.

Description

Technical Field

[0001] The invention belongs to the technical field of analysis and detection, and particularly relates to a trace detection method for testing mercury cadmium telluride materials using a glow discharge mass spectrometer and an application thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] Mercury cadmium telluride (HgCdTe) is a core material for third-generation infrared detectors. Its impurity content (especially trace elements such as Li, Na, and Cu) directly affects the device's dark current, noise performance, and responsivity. Currently, impurity analysis of high-purity metal or semiconductor materials primarily relies on methods such as glow discharge mass spectrometry (GD-MS) and inductively coupled plasma mass spectrometry (ICP-MS). However, existing technologies are difficult to directly apply to trace detection of HgCdTe materials due to the following technical bottlenecks: 1. Interference problems caused by the complexity of material components HgCdTe material contains volatile element mercury (Hg, boiling point 357℃) and high melting point elements cadmium (Cd, melting point 321℃) and tellurium (Te, melting point 450℃). During the high temperature sputtering process of traditional GD-MS (usually >500℃), Hg is easily volatilized and lost, while Cd / Te easily forms polyatomic ions (such as CdTe + 、Te2 + ), which seriously interferes with the mass spectrometry peak identification of trace impurities. For example, when using conventional GD-MS to detect high-purity copper, a control current of only 5-10mA is sufficient to detect trace impurities. However, directly applying this to mercury cadmium telluride can cause Hg component evaporation, unbalance the matrix ratio, and distort the detection results.

[0004] The contradiction between sensitivity and matrix effect. To improve sensitivity, existing GD-MS technology often adopts the strategy of increasing discharge current (such as > 5mA) or extending sputtering time (such as > 2h). However, this will cause the following problems for HgCdTe materials: Thermal decomposition risk: Local overheating under high current will accelerate the destruction of the HgCdTe lattice and produce non-stoichiometric defects; Increased matrix interference: The high sputtering yield of Cd / Te will mask the low-content impurity signal.

[0005] While GD-MS has been used for the detection of some compound semiconductors (such as GaAs and InP), there are virtually no reports on its application to HgCdTe. While existing technologies employ GD-MS for the detection of high-purity arsenic, they do not address the cryogenic control of volatile metals. While liquid nitrogen-cooled GD-MS has been proposed for the detection of elemental Hg, this approach does not address the stability issues associated with the coordinated sputtering of multiple elements in a multi-element compound (HgCdTe).

[0006] Therefore, developing a GD-MS trace detection method for HgCdTe material properties requires fundamentally reconstructing the parameter system to resolve the contradiction between thermal stability, matrix interference and sensitivity. This has become a technical problem that urgently needs to be overcome in this field. Summary of the Invention In order to address the deficiencies of the prior art, the present invention aims to provide a method and application for detecting trace amounts of mercury cadmium telluride materials using a glow discharge mass spectrometer. The detection method provided by the present invention has high sensitivity and accuracy, a wide testing range, and is suitable for rapid testing of a variety of trace impurity elements in high-purity mercury cadmium telluride materials. The detection limit for most impurity elements can be as low as ppb (parts per billion) or ppm (parts per million).

[0007] In order to achieve the above object, the technical solution of the present invention is: A first aspect of the present invention provides a method for detecting trace amounts of mercury cadmium telluride materials using a glow discharge mass spectrometer, comprising: The mercury cadmium telluride sample was placed on an indium bar and tested using the auxiliary cathode method. Under liquid nitrogen cooling conditions, the discharge voltage was controlled to 800-850V, the discharge current was less than 3.0 mA, the sputtering time was 40-60 min, and the sample loading amount was 10-21 mg, achieving ppm-level impurity detection.

[0008] Existing techniques mostly target single metals (such as high-purity copper and iron), whereas HgCdTe is a multi-component compound with poor thermal stability and easy decomposition. To address this, the present invention utilizes liquid nitrogen cooling for testing. By regulating the discharge voltage, discharge current, sputtering time, and sample loading, the glow discharge stability is maintained at low temperatures. This prevents melting of the indium bar and suppresses thermal decomposition of HgCdTe while ensuring effective sputtering of impurity elements (such as Li, Na, and Al), reducing Hg loss and enabling ppb or ppm-level impurity detection. This also results in stable and reproducible test results, addressing the issues of insufficient sensitivity and matrix interference in glow discharge mass spectrometry testing of HgCdTe materials due to the presence of volatile Hg and high-melting-point Cd / Te. Existing techniques typically operate at room temperature or at higher currents (e.g., 5-10 mA), making them unsuitable for heat-sensitive materials such as HgCdTe.

[0009] In some embodiments of the present invention, the purity of the HgCdTe sample is 99.99%-99.999%. The high purity of the matrix (HgCdTe) can significantly reduce the interference of polyatomic ions generated by the material itself (such as CdTe + 、Hg2 + ion peaks obscuring trace impurity signals (such as Li, Na, and Cu). Purity of 99.99%-99.999% is essential for accurate detection of ppb-level impurities in HgCdTe materials and is a key indicator for ensuring semiconductor device performance.

[0010] The present invention innovatively uses indium bars as carriers combined with auxiliary cathode design, and achieves stable fixation of HgCdTe samples through the flexibility and conductivity of indium. The auxiliary cathode optimizes discharge uniformity, avoids local overheating that causes Hg volatilization or material decomposition, solves the problem of brittle materials being difficult to sputter uniformly, and improves the stability of impurity signals. The size design of the indium bar is the key point to ensure the accuracy and repeatability of HgCdTe trace detection. In order to improve the detection accuracy, in some embodiments of the present invention, the indium bar is in the shape of a rod with a size of (2-4) mm × (2-4) mm × (20-22) mm. Its cross-sectional area is 2-4 mm 2 , can provide sufficient surface area (4-16mm 2 ) ensures stable attachment of the HgCdTe sample (10-21 mg) while avoiding uneven discharge due to excessively large areas. A width / thickness of 2-4 mm accommodates low-current discharges less than 3.0 mA, avoiding edge discharge concentration ("edge effect") caused by excessive carrier width. A length of 20-22 mm allows for extended reach into the liquid nitrogen cooling area. The high thermal conductivity of indium (82 W / (m·K)) allows for rapid cooling, suppressing Hg volatilization (controlling the temperature ≤-150°C). This length also ensures uniform plasma coverage of the sample area, reducing uneven sputtering crater depth.

[0011] Preferably, the indium bar measures 3 mm × 3 mm × 21 mm. This size of indium bar achieves an optimal balance between thermal management (liquid nitrogen cooling), discharge stability (low current adaptation), mechanical reliability (compression and bending resistance), and interference suppression (low background), and is a key innovation in ensuring the accuracy and repeatability of HgCdTe trace detection.

[0012] Indium naturally forms an indium oxide (In2O3) film (approximately several nanometers thick) in air, which can also absorb organic contaminants (such as grease and dust). Nitric acid, especially dilute nitric acid, effectively dissolves indium oxide (reaction: In2O3 + 6HNO3 → 2In(NO3)3 + 3H2O) and oxidizes and decomposes organic impurities. Surface oxides and contaminants can reduce the electrical conductivity of the indium and mercury cadmium telluride (HgCdTe) sample, leading to unstable discharge (such as voltage fluctuations) and affecting the sputtering efficiency of the impurity elements.

[0013] Therefore, in some embodiments of the present invention, the indium bar is pretreated before the mercury cadmium telluride material is placed on the indium bar, wherein the pretreatment includes: cleaning the indium bar with nitric acid, then cleaning with water and ethanol and drying, so that the indium bar exhibits a silver metallic luster after cleaning; and then pressing the mercury cadmium telluride sample onto the indium bar for testing.

[0014] The present invention prefers to use nitric acid for pretreatment instead of ethanol, acetone or hydrochloric acid. This is because ethanol / acetone ultrasonic cleaning can only remove organic pollutants, but cannot remove oxide layers or metal impurities; hydrochloric acid can dissolve oxides, but may introduce Cl - Residue (interferes with Cl element detection in GD-MS), while nitric acid residue (NO3 - ) It is easier to volatilize and desorb in a vacuum environment, and nitric acid cleaning will not introduce new pollution.

[0015] After cleaning with nitric acid, the indium surface presents a fresh metallic state, and its ductility and adhesion are significantly enhanced, making it easier to fit closely with the HgCdTe sample during subsequent pressing (avoiding uneven local discharge due to interface gaps).

[0016] It should be noted that when the HgCdTe sample is pressed onto the indium bar, the HgCdTe sample and the pressing rod are separated by weighing paper to avoid direct contact, thereby preventing the HgCdTe sample from being contaminated and ensuring accurate test results.

[0017] Preferably, cleaning the indium bar with nitric acid includes placing the indium bar in nitric acid for 10-30 minutes. If the cleaning time is too short (less than 10 minutes), the cleaning is incomplete, and the risk of residual oxides is high. If the cleaning time is too long (greater than 30 minutes), excessive corrosion of the indium may occur, increasing surface roughness and affecting sample loading flatness.

[0018] Preferably, 5-10% dilute nitric acid is used to balance the cleaning effect and indium loss.

[0019] In some embodiments of the present invention, the method of testing using an auxiliary cathode includes: The internal cavity of the glow discharge mass spectrometer was cleaned with cleaning fluid, and then immersed in aqua regia for 20-40 min. After being taken out and cleaned with water and dried, it was placed in the cleaned glow discharge mass spectrometer, calibrated, and then tested.

[0020] Understandably, the internal cavity of a glow discharge mass spectrometer primarily consists of a sample cell and an extraction lens, both constructed from tantalum. During testing, the sputtering products from the sample deposit on the surface of the sample cell, creating a memory effect that interferes with the signal from subsequent samples. Therefore, before testing a new sample, the sample cell and extraction lens must be cleaned to eliminate the memory effect and ensure accurate test results. After cleaning with cleaning fluid and aqua regia, the discharge current fluctuations at the auxiliary cathode are reduced, significantly improving signal repeatability.

[0021] In some embodiments of the present invention, the cleaning liquid is any one or more of hydrofluoric acid, nitric acid and sulfuric acid.

[0022] In some embodiments of the present invention, the cleaning solution is a mixture of hydrofluoric acid and nitric acid, wherein the volume ratio of the hydrofluoric acid to the nitric acid is 1:(1-5). Preferably, the volume ratio of the hydrofluoric acid to the nitric acid is 1:3. Using a mixed acid solution of hydrofluoric acid and nitric acid to clean the tantalum material inside the cavity can remove the deposited layer attached to the cavity surface, thereby avoiding high test results for some elements.

[0023] During the detection process, the present invention adopts a combination of aqua regia cleaning + auxiliary cathode (In115) technology, which solves the core interference problem in high-sensitivity GD-MS detection through the triple effects of pollution removal, discharge optimization and memory effect suppression. It is particularly suitable for trace analysis of volatile, multi-component materials such as HgCdTe.

[0024] GD-MS detection of trace impurities requires both high sensitivity (low detection limits) and high resolution (distinguishing adjacent mass spectral peaks). Conventional calibration methods struggle to achieve this balance, resulting in low-level impurity signals being masked by the matrix or adjacent peaks. Therefore, the present invention defines a specific calibration method.

[0025] In some embodiments of the present invention, when calibrating a clean glow discharge mass spectrometer, the discharge voltage is adjusted to 1000-1100 V and the discharge current is ≤3 mA; the vertical source lens voltage (Source V1), the horizontal source lens voltage (Source H1), the extraction lens voltage (Extractor), the horizontal transmission lens voltage (Trans Hor Lens), the vertical transmission lens voltage (Trans Vert Lens) and the quadrupole lens voltage (IC-Quard2) are adjusted so that the Ta181 signal reaches 1E -9, resolution>4000, and at the same time correct the quadrupole efficiency coefficient to 0.8-1.1, so that the test result ratio of Ta180 and Ta181 is (0.9-1.1):(0.9-1.1), completing the calibration.

[0026] The calibration method of the present invention adjusts the vertical / horizontal lens voltage and the quadrupole lens voltage to make the Ta181 signal reach 1E -9 , while achieving a resolution greater than 4000, achieving a balance between high sensitivity and resolution. The quadrupole efficiency coefficient (0.8-1.1) was corrected to bring the Ta180 / Ta181 ratio close to the theoretical value (1:1), ensuring consistent transmission efficiency for ions across all mass ranges. Using chemically stable, memory-free Ta isotopes as calibration references, a reproducible calibration baseline was established through fixed voltage parameters, achieving long-term detection stability.

[0027] Calibration improves the accuracy and reliability of trace detection, standardizes operational procedures, and reduces human error. The calibrated instrument is compatible with different matrix materials (such as HgCdTe and GaAs), adapting to the detection needs of multiple materials. Ta calibration eliminates mass discrimination, ensuring the quantitative accuracy of elements such as Cd, Te, and Hg. This calibration method systematically addresses three core issues in ultra-high-sensitivity GD-MS detection (sensitivity-resolution conflict, mass discrimination, and signal drift) through multi-parameter collaborative optimization. It is particularly suitable for trace analysis of complex materials such as HgCdTe, providing reliable technical support for semiconductor material quality control.

[0028] In some embodiments of the present invention, when testing using the auxiliary cathode method, the mercury cadmium telluride material is sampled in the form of a needle sample, the discharge voltage and discharge current are controlled, and the sample is cooled to -180°C with liquid nitrogen for testing.

[0029] The Hg in HgCdTe is volatile at room temperature (boiling point 357°C), and the high-temperature sputtering of traditional GD-MS will cause an imbalance in the sample composition and distort the detection results. During the detection process, the present invention uses liquid nitrogen to cool to -180°C, reducing the sample temperature to below the critical point of Hg volatilization (the vapor pressure of Hg at -180°C is negligible) to maintain a stable stoichiometric ratio; combined with the needle-shaped sample design, it increases the surface area-volume ratio, accelerates the cooling efficiency, avoids heat accumulation inside the sample, and solves the problems of Hg volatilization and thermal decomposition of the material. In addition, the needle-shaped sample can focus the plasma and reduce lateral diffusion; combined with the auxiliary cathode to disperse the electric field, the sputtering area is homogenized, improving the discharge uniformity and signal stability. The volatility of Cd / Te is reduced at low temperatures, reducing CdTe + 、Te2 +When needle-shaped samples are injected, they can be sputtered efficiently, exposing impurities more fully per unit volume, improving signal intensity and solving the problem of insufficient sensitivity in detecting trace impurities.

[0030] Preferably, when the auxiliary cathode method is used for testing, the mercury cadmium telluride sample particles are pressed on the indium bar and sampled in the form of a needle sample, the discharge voltage is controlled to 800V and the discharge current is 1.6 mA, and the sample is cooled to -180°C with liquid nitrogen for testing.

[0031] Adjust the instrument parameters to maximize the matrix signal, about 1E -11 , with a resolution greater than 4000. The instrument then collects signals from trace impurity elements and matrix elements, and automatically calculates the impurity concentration based on the abundance and relative sensitivity factor (RSF) of each element. During the test, the matrix element is Te, and its content is automatically calculated as 1,000,000.

[0032] The content of the element x to be measured is calculated using the following formula:

[0033] Where: is the RSF value of the element to be measured x and the RSF value of the matrix element tellurium Te, and are the isotopic abundances of the matrix element tellurium and the element to be measured, = is the ratio of the integrated area of ​​the spectrum peak of the isotope of the element to be measured, x, to that of the matrix element, tellurium. Since element abundance is automatically calculated during quantification, only one isotope needs to be selected for an element with multiple isotopes.

[0034] In some embodiments of the present invention, the sputtering time of the mercury cadmium telluride sample is 50 min, and the loading amount of the mercury cadmium telluride sample is 16 mg.

[0035] During experiments, the inventors discovered that using a glow discharge mass spectrometer with direct solid injection—pressing sample particles onto an indium bar and injecting them in a needle-like manner—can avoid the introduction of impurities during sample preparation. Furthermore, using a voltage of 800-850V and a current below 3mA can detect trace impurities in high-purity samples. This method exhibits high sensitivity, achieving low detection limits ranging from ppb to ppm, meeting the requirements for detecting high-purity HgCdTe semiconductor materials. A possible reason for this is that the auxiliary cathode metal indium, combined with the sample, can reduce interference from impurity elements at appropriate voltages and low currents due to its lower melting point. However, the inventors further discovered that using a voltage of 800-850V and a current below 3mA can detect trace impurities in high-purity HgCdTe powder. This is suspected to be due to the fact that exceeding the preferred voltage and current ranges can cause the indium bar to melt, increasing background interference from impurities. Furthermore, using too low a voltage and current can lead to unstable test results, resulting in large deviations between groups and affecting reproducibility.

[0036] When using a glow discharge mass spectrometer to test and analyze HgCdTe samples, the signals of some elements will be interfered with. The interference mainly comes from the following aspects: 1) Interference of the sample matrix. In the test of HgCdTe powder sample, since the contents of the three elements of HgCdTe are all greater than 1%, these matrix elements form polyatomic complex ion clusters with carbon, hydrogen, oxygen, and nitrogen in the air. These have similar masses to the impurity ions to be measured and cannot be distinguished by the instrument, thus becoming interference signals. The final signal detected by the instrument is the sum of the interference signal and the signal of the element to be measured. The two signals cannot be distinguished, so the element to be measured cannot be accurately quantified. For example, the interference signal of Cs133 includes C 13 Te 120 + , O 17 Cd 116 + etc., and Cs has only one isotope, Cs113, and cannot be distinguished by selecting different isotopes.

[0037] 2) Instrument background interference: This part of the interference mainly comes from the glow discharge gas argon, the auxiliary cathode metal indium and the cavity internal material tantalum. 36 In 115 + Interference with Eu151 signal.

[0038] Interference can be eliminated in some ways. For example, for elements such as Fe and Mn, the interference peaks and the peaks of real sample impurities can be distinguished by the slit in the equipment. By modifying the parameters of IC-Quad2 and the slit position, the resolution can reach more than 4000 to distinguish the signal of the element to be measured from the interference signal. Finally, the signal can be directly used as the final result. In addition, choosing the right isotope can also avoid the influence of interference. For example, among the isotopes of Ca, the most abundant one is Ca40, with an abundance of 96.9%, while its interfering element is Ar40. + , which can cause very strong interference, so Ca44, which has less interference, was selected as the test element. When the interference peak intensity is strong and overlaps with the actual sample peak, it is impossible to distinguish whether the signal peak originates from the sample or the interference. As a result, the purity of some elements cannot be accurately measured and they can only exist in the form of interference. Elements that cannot be accurately quantified are marked as interferences, including I, Cs, La, Ce, Nd, Tl, and Sm.

[0039] By changing the resolution and selecting appropriate isotopes for testing, the interference caused by impurity elements is avoided, so that the test results reflect the content of impurity elements in the sample as realistically as possible, improving the accuracy of the test and providing a certain reference for setting the detection limit.

[0040] A second aspect of the present invention provides an application of the above-mentioned trace detection method in the analysis and detection of trace impurities in mercury cadmium telluride semiconductive materials.

[0041] The beneficial effects of the present invention are: This invention provides a method for detecting trace amounts of HgCdTe materials using a glow discharge mass spectrometer. By using a coordinated design of an indium strip carrier and an auxiliary cathode, combined with liquid nitrogen cooling and low-power discharge parameters (800-850 V, <3.0 mA), this method achieves high-precision and high-stability detection of ppm-level impurities in HgCdTe materials. This method directly addresses the long-standing technical bottleneck in detecting trace impurities in HgCdTe in the semiconductor materials field and provides a reliable analytical method for improving the yield of infrared focal plane arrays. Specifically, it is demonstrated as follows: (1) Inhibition of mercury volatilization and thermal decomposition: Liquid nitrogen cooling (below -180°C) reduces the Hg vapor pressure to a negligible level. Combined with low current (<3.0 mA) sputtering, the Hg loss rate is extremely low, ensuring the authenticity of the HgCdTe stoichiometric ratio; (2) Improved signal stability: The ductility of the indium strip and the plasma control of the auxiliary cathode significantly improve the sputtering uniformity, and the relative standard deviation (RSD) of impurity detection is much better than that of traditional methods; (3) Breaking through the detection sensitivity limit: At a low sample amount of 10-21 mg, by optimizing the sputtering time (40-60 min), a detection limit of 0.01 ppm for impurity elements (14 elements: lithium, sodium, magnesium, aluminum, silicon, phosphorus, sulfur, chlorine, calcium, titanium, potassium, iron, selenium, and zirconium) is achieved, meeting the stringent requirements of infrared detectors for trace contamination control.

[0042] (4) Compatible with industrial standardization: The indium carrier and parameter system are compatible with mainstream GD-MS equipment, without the need for complex modifications, and the cost of a single test is reduced by 30%.

[0043] Furthermore, the trace detection method for mercury cadmium telluride materials using a glow discharge mass spectrometer described in the present invention adopts direct solid (needle-shaped sample) sampling, avoiding the introduction of impurities during the sample preparation process. It has high sensitivity and accuracy, a wide testing range, and is suitable for rapid testing of multiple trace impurity elements in high-purity substances. The detection limit for most impurity elements can be as low as ppb (parts per billion) or ppm (parts per million).

[0044] The present invention discloses a method for detecting trace amounts of mercury cadmium telluride materials using a glow discharge mass spectrometer, which has fast detection speed, high sensitivity, and high accuracy. The method is used to determine the impurity content and purity of mercury cadmium telluride powder. The method optimizes glow discharge parameters by detecting elemental data signals, and tests samples. The method has high sensitivity and low detection limits, and can detect most elements within a range of ppm to ppb, thus meeting the detection requirements for high-purity mercury cadmium telluride semiconductor materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0046] Figure 1 The effect of sputtering time on the Si28 signal in Examples 1-5 of the present invention; Figure 2 The effect of sputtering time on the signal of substrate Te130 in Examples 1-5 of the present invention; Figure 3 The effect of sputtering time on the signal of S32 in Examples 1-5 of the present invention; Figure 4 The effect of sputtering time on the signal of Hg2O2 in Examples 1-5 of the present invention; Figure 5 The effect of sample loading on the signal of Te130 matrix in Examples 1, 6, and 7 of the present invention; Figure 6 The effect of sample loading on the signal of impurity Na23 in Examples 1, 6, and 7 of the present invention; Figure 7 The effect of sample loading on the Hg2O2 signal in Examples 1, 6, and 7 of the present invention; Figure 8 The signal effect of the discharge current on the substrate Te130 in Examples 1, 8-12 of the present invention; Figure 9 The effect of the discharge current on the signal of the auxiliary cathode In115 in Examples 1, 8-12 of the present invention; Figure 10 The signal effect of the discharge current on Hg2O2 in Examples 1, 8-12 of the present invention; Figure 11 The signal effect of the discharge current on Na23 in Examples 1, 8-12 of the present invention; Figure 12 The effect of the discharge current on the signal S32 in Examples 1, 8-12 of the present invention; Figure 13 The signal effect of the discharge current on Fe57 in Examples 1, 8-12 of the present invention; Figure 14 The signal effect of the discharge current on Zr90 in Examples 1, 8-12 of the present invention; Figure 15 The effect of discharge voltage on the signal of Zr90 in Examples 1, 13, and 14 of the present invention; Figure 16 The signal effect of the discharge voltage on the substrate Te130 in Examples 1, 13, and 14 of the present invention; Figure 17 The effect of discharge voltage on Hg2O2 signal in Examples 1, 13 and 14 of the present invention; Figure 18 This is the effect of the discharge voltage on the signal of Si28 in Examples 1, 13, and 14 of the present invention. DETAILED DESCRIPTION

[0047] Example 1 A method for detecting trace amounts of mercury cadmium telluride (HgCdTe) using a glow discharge mass spectrometer comprises the following steps: S1 Prepare samples: A high-purity mercury cadmium telluride material is prepared into a sample to be tested, and the purity of the high-purity mercury cadmium telluride material is 99.99%-99.999%.

[0048] The indium bars were cut into 3 mm × 3 mm × 21 mm rods, then washed in 8% dilute nitric acid for 20 min, and then washed with high-purity water and ethanol and blown dry. After cleaning, the indium bars exhibited a silver metallic luster. The high-purity mercury cadmium telluride material was then pressed onto the indium bars for testing. The sample and the pressing rod were separated by weighing paper to avoid direct contact.

[0049] S2 sample testing; The internal cavity of the glow discharge mass spectrometer was cleaned with a cleaning solution (a combination of hydrofluoric acid and nitric acid, with a volume ratio of 1:3). The internal cavity was then immersed in aqua regia for 30 min, then rinsed with clean water and blown dry, and then placed in the clean glow discharge mass spectrometer for later use.

[0050] Calibrate the instrument: adjust the discharge current so that the discharge voltage is controlled at 1000V-1100V and the discharge current is controlled at 3 mA. Then adjust the vertical source lens voltage (Source V1), horizontal source lens voltage (Source H1), extraction lens voltage (Extractor), horizontal transmission lens voltage (Trans Hor Lens), vertical transmission lens voltage (Trans VertLens) and quadrupole lens voltage (IC-Quard2) so that the Ta181 signal reaches 1E -9 , with a resolution greater than 4000. At the same time, the quadrupole efficiency coefficient (between 0.8 and 1.1) and the electron multiplier voltage were corrected so that the ratio of the Ta180 and Ta181 test results was close to 1:1, and the instrument calibration was completed.

[0051] Testing: Using the auxiliary cathode method, high-purity HgCdTe was pressed onto an indium bar and injected as a needle. The discharge voltage was controlled at 800 V and the discharge current was 1.6 mA. The sample was cooled to -180°C with liquid nitrogen. The sputtering time was 50 minutes, and the sample loading was 16 mg. Six parallel tests were performed. The results are shown in Table 1.

[0052] S3 data analysis: The glow discharge mass spectrometer automatically analyzed the data. The performance test results are shown in Table 1.

[0053] Table 1 Performance test results of Example 1

[0054] Based on the test results under the above discharge conditions, HgCdTe powder samples were tested six times under the optimized discharge conditions (voltage 800V, current 1.6mA). The results showed that the main impurities in the HgCdTe sample were lithium, sodium, magnesium, aluminum, silicon, phosphorus, sulfur, chlorine, calcium, titanium, potassium, iron, selenium, and zirconium. The detected amounts of these elements relative to tellurium were 0.24, 0.44, 0.21, 0.41, 10.2, 0.25, 1.8, 6.0, 0.29, 0.47, 0.06, 0.41, 0.59, and 0.16 ppm, respectively. Indium, tantalum, iodine, cesium, lanthanum, cerium, neodymium, thallium, and samarium could not be accurately quantified due to interference from matrix elements. Tellurium, cadmium, and mercury are matrix elements; the remaining elements were all below the detection limit. The overall purity of the material is between 99.99% and 99.999%.

[0055] Example 2 A method for detecting trace amounts of mercury cadmium telluride materials using a glow discharge mass spectrometer is disclosed. The method differs from Example 1 in that the sputtering time of the detection sample is 20 minutes, and the remaining steps are identical to those of Example 1.

[0056] The data test results of Si28 are shown in Figure 1 , the test results of Te130 matrix are shown in Figure 2 , the data test results of S32 are shown in Figure 3 , Hg2O2 data test results are shown in Figure 4 .

[0057] Example 3 A method for detecting trace amounts of mercury cadmium telluride materials using a glow discharge mass spectrometer is disclosed. The method differs from Example 1 in that the sputtering time of the detection sample is 10 minutes, and the remaining steps are identical to those of Example 1.

[0058] The data test results of Si28 are shown in Figure 1 , the test results of Te130 matrix are shown in Figure 2 , the data test results of S32 are shown in Figure 3 , Hg2O2 data test results are shown in Figure 4 .

[0059] Example 4 A method for detecting trace amounts of mercury cadmium telluride materials using a glow discharge mass spectrometer is disclosed. The method differs from Example 1 in that the sputtering time of the detection sample is 60 minutes, and the remaining steps are identical to those of Example 1.

[0060] The data test results of Si28 are shown in Figure 1 , the test results of Te130 matrix are shown in Figure 2 , the data test results of S32 are shown in Figure 3 , Hg2O2 data test results are shown in Figure 4 .

[0061] Example 5 A method for detecting trace amounts of mercury cadmium telluride materials using a glow discharge mass spectrometer is disclosed. The method differs from Example 1 in that the sputtering time of the detection sample is 40 minutes, and the remaining steps are identical to those of Example 1.

[0062] The data test results of Si28 are shown in Figure 1 , the test results of Te130 matrix are shown in Figure 2 , the data test results of S32 are shown in Figure 3 , Hg2O2 data test results are shown in Figure 4 .

[0063] Example 6 A method for detecting trace amounts of mercury cadmium telluride materials using a glow discharge mass spectrometer is disclosed. The method differs from Example 1 in that the loading amount of the detection sample is 21 mg, and the remaining steps are completely consistent with those of Example 1.

[0064] The test results of Te130 matrix are shown in Table 2, the test results of impurity H2O2 are shown in Table 3, and the test results of impurity Na23 are shown in Table 4. Figure 5 , the data test line chart of impurity Na23 is shown in Figure 6 , Hg2O2 data test line chart see Figure 7 .

[0065] Example 7 A method for detecting trace amounts of mercury cadmium telluride materials using a glow discharge mass spectrometer is provided. The method differs from Example 1 in that the loading amount of the detection sample is 10 mg, and the remaining steps are identical to those of Example 1.

[0066] The test results of Te130 matrix are shown in Table 2, the test results of impurity Na23 are shown in Table 4, and the test results of impurity H2O2 are shown in Table 3. Figure 5 , the data test line chart of impurity Na23 is shown in Figure 6 , Hg2O2 data test line chart see Figure 7 .

[0067] Example 8 A method for detecting trace amounts of mercury cadmium telluride materials using a glow discharge mass spectrometer is disclosed. The method differs from Example 1 in that the discharge current is 1.4 mA, and the remaining steps are identical to those of Example 1.

[0068] The test results are shown in Table 5, and the test line graph of the Te130 matrix is ​​shown in Figure 8 , the data test line chart of auxiliary cathode In115 is shown in Figure 9, Hg2O2 data test line chart see Figure 10 , the data test line chart of Na23 is shown in Figure 11 , the data test line chart of S32 is shown in Figure 12 , Fe57 data test line chart see Figure 13 , Zr90 data test line chart see Figure 14 .

[0069] Example 9 A method for detecting trace amounts of mercury cadmium telluride materials using a glow discharge mass spectrometer is disclosed. The method differs from Example 1 in that the discharge current is 1.2 mA, and the remaining steps are identical to those of Example 1.

[0070] The test results are shown in Table 5, and the test line graph of the Te130 matrix is ​​shown in Figure 8 , the data test line chart of auxiliary cathode In115 is shown in Figure 9 , Hg2O2 data test line chart see Figure 10 , the data test line chart of Na23 is shown in Figure 11 , the data test line chart of S32 is shown in Figure 12 , Fe57 data test line chart see Figure 13 , Zr90 data test line chart see Figure 14 .

[0071] Example 10 A method for detecting trace amounts of mercury cadmium telluride materials using a glow discharge mass spectrometer is disclosed. The method differs from Example 1 in that the discharge current is 1.0 mA, and the remaining steps are identical to those of Example 1.

[0072] The test results are shown in Table 5, and the test line graph of the Te130 matrix is ​​shown in Figure 8 , the data test line chart of auxiliary cathode In115 is shown in Figure 9 , Hg2O2 data test line chart see Figure 10 , the data test line chart of Na23 is shown in Figure 11 , the data test line chart of S32 is shown in Figure 12 , Fe57 data test line chart see Figure 13 , Zr90 data test line chart see Figure 14 .

[0073] Example 11 A method for detecting trace amounts of mercury cadmium telluride materials using a glow discharge mass spectrometer is disclosed. The method differs from Example 1 in that the discharge current is 0.8 mA, and the remaining steps are identical to those of Example 1.

[0074] The test results are shown in Table 5, and the test line graph of the Te130 matrix is ​​shown in Figure 8 , the data test line chart of auxiliary cathode In115 is shown in Figure 9 , Hg2O2 data test line chart see Figure 10 , the data test line chart of Na23 is shown in Figure 11 , the data test line chart of S32 is shown in Figure 12 , Fe57 data test line chart see Figure 13 , Zr90 data test line chart see Figure 14 .

[0075] Example 12 A method for detecting trace amounts of mercury cadmium telluride materials using a glow discharge mass spectrometer is disclosed. The method differs from Example 1 in that the discharge current is 0.6 mA, and the remaining steps are identical to those of Example 1.

[0076] The test results are shown in Table 5, and the test line graph of the Te130 matrix is ​​shown in Figure 8 , the data test line chart of auxiliary cathode In115 is shown in Figure 9 , Hg2O2 data test line chart see Figure 10 , the data test line chart of Na23 is shown in Figure 11 , the data test line chart of S32 is shown in Figure 12 , Fe57 data test line chart see Figure 13 , Zr90 data test line chart see Figure 14 .

[0077] Example 13 A method for detecting trace amounts of mercury cadmium telluride materials using a glow discharge mass spectrometer is disclosed. The method differs from Example 1 in that the discharge voltage is 600 V, and the remaining steps are identical to those of Example 1.

[0078] Zr90 data test line chart see Figure 15 , the data test line chart of the substrate Te130 is shown in Figure 16 , Hg2O2 data test line chart see Figure 17 , Si28 data test line chart see Figure 18 .

[0079] Example 14 A method for detecting trace amounts of mercury cadmium telluride materials using a glow discharge mass spectrometer is disclosed. The method differs from Example 1 in that the discharge voltage is 700 V, and the remaining steps are identical to those of Example 1.

[0080] Zr90 data test line chart see Figure 15 , the data test line chart of the substrate Te130 is shown in Figure 16 , Hg2O2 data test line chart see Figure 17 , Si28 data test line chart see Figure 18 .

[0081] Table 2 Test results of Te130 matrix

[0082] Table 3 Test results of Hg2O2

[0083] Table 4 Test results of impurity Na23

[0084] The signal intensities of different elements, including impurity elements (Si, S), matrix elements (Te), and dopant elements (Hg), vary with sputtering time. Tables 2, 3, and 4 show that the signal of the matrix element Te130 is stable from the outset. The sputtering signals of the impurity elements Si28 and S32, as well as the dopant element Hg2O2, gradually stabilize as the signal stabilization time increases.

[0085] The Te130 signal intensity remains essentially stable for samples of varying mass. The signal intensities for the 21 mg and 16 mg samples are significantly higher than those for the 10 mg sample, indicating that increasing the sample mass significantly increases the main signal intensity. The difference in signal intensity between the 21 mg and 16 mg samples is minimal, primarily due to the fact that the indium strips are completely covered by the sample, resulting in similar surface areas. During glow discharge ionization, argon ions uniformly bombard the sample surface, causing the atoms that make up the sample to leave the sample surface with a uniform flux.

[0086] For Hg2O2 doped in powder samples, the signal gradually stabilizes with sputtering time. The long stabilization time is likely due to uneven sample distribution, resulting in a high concentration of free Hg on the particle surface. Furthermore, varying sample loading can affect the signal; increasing the sample loading significantly increases signal intensity.

[0087] For impurity elements in powder samples, such as Na₂₃, the signal collection differs from that of Te and Hg due to their lower signal intensity. Te and Hg, as matrix signals, have higher intensities and are primarily collected by the Faraday cup, while Na is collected by the electron multiplier. However, the signal results are similar to those of Hg₂O₂, with the signal gradually stabilizing with sputtering, and the signal intensity of samples with higher loadings is stronger than that of samples with lower loadings.

[0088] Table 5 Test results of Examples 1, 8-12

[0089] As shown in Table 5, with the increase of glow discharge current, the signal of the matrix Te130 gradually increases and reaches a stable state at around 1.2 mA. There is no obvious change in the signal when the current is further increased.

[0090] In this invention, the auxiliary cathode provides a support for the sample, allowing the powder sample to be tested using a needle-like injection method. It acts as a conductor, transferring charge accumulated on the sample surface. The indium bar, acting as both a conductor and a support for the sample, produces a very strong signal, increasing linearly with increasing discharge current. Therefore, actual test results will not include indium test results. Furthermore, indium has a low melting point, necessitating a lower discharge current to prevent the indium bar from melting in the device.

[0091] Hg, as a doping element, has a strong signal value, so it is also detected using a Faraday cup. As the discharge current increases, the signal intensity also increases until it reaches a stable level.

[0092] The signal of impurity elements (Na23, S32, Fe57, Zr90) changes at different currents. Generally, the signal increases with the current and remains stable between 1.2 mA and 1.6 mA.

[0093] The signal changes of different elements under different discharge voltage conditions. The signal of each element increases to varying degrees with increasing discharge voltage. Because the discharge voltage and discharge current have an impact on each other, excessively high voltage can easily cause the auxiliary cathode to melt.

[0094] Enhancing the signal intensity of an element can increase the accuracy of the test and reduce the detection limit to a certain extent. The element signals collected by the equipment are mainly achieved by adjusting the glow discharge conditions and debugging the parameters for collecting signals. By adjusting the glow discharge conditions, adjusting the discharge voltage and current, increasing the sputtering rate and ionization efficiency of the sample material, and minimizing the interference caused by sample surface contamination, the test results are made more accurate. In addition, the GDMS quantitative process is obtained by converting the ratio of the impurity signal to the substrate signal through RSF. Increasing the signal intensity can enhance the substrate signal and reduce the detection limit. Finally, adjusting the signal parameters can maximize the collection of element signals of the constituent materials and ensure the accuracy of the test. The present invention enhances the signal intensity of the element by optimizing the discharge voltage, discharge current, sputtering time and sample loading amount. Under the conditions of discharge voltage 800-850V, discharge current less than 3.0 mA, sputtering time 40-60 min and sample loading amount of 10-21 mg, rapid testing of multiple trace impurity elements in high-purity substances is achieved, and the detection limit for most impurity elements can be as low as ppb or ppm.

[0095] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for detecting trace amounts of mercury cadmium telluride materials using a glow discharge mass spectrometer, characterized in that: include: The mercury cadmium telluride sample was placed on an indium bar and tested using the auxiliary cathode method. Under liquid nitrogen cooling conditions, the discharge voltage was controlled to 800-850V, the discharge current was less than 3.0 mA, the sputtering time was 40-60 min, and the sample loading amount was 10-21 mg, achieving ppm-level impurity detection.

2. The trace detection method according to claim 1, wherein The purity of the mercury cadmium telluride sample is 99.99%-99.999%.

3. The trace detection method according to claim 1, wherein The indium bar is in a rod shape, and has a size of (2-4) mm×(2-4) mm×(20-22) mm.

4. The trace detection method according to claim 1, wherein The indium bar is pretreated before the mercury cadmium telluride material is placed on the indium bar, wherein the pretreatment includes: cleaning the indium bar with nitric acid, then cleaning with water and ethanol and drying, and then pressing the mercury cadmium telluride sample onto the indium bar for testing.

5. The trace detection method according to claim 1, wherein The method test using the auxiliary cathode includes: The internal cavity of the glow discharge mass spectrometer was cleaned with an acid solution, and then immersed in aqua regia for 20-40 minutes. After being taken out and cleaned with water and dried, it was placed in the cleaned glow discharge mass spectrometer, calibrated, and then tested.

6. The trace detection method according to claim 5, wherein: The acid is any one or more of hydrofluoric acid, nitric acid and sulfuric acid.

7. The trace detection method according to claim 5, wherein: The acid solution is a mixture of hydrofluoric acid and nitric acid, and the volume ratio of the hydrofluoric acid to the nitric acid is 1:(1-5).

8. The trace detection method according to claim 5, wherein: When calibrating the cleaned glow discharge mass spectrometer, adjust the discharge voltage to 1000-1100 V and the discharge current to ≤3 mA; adjust the vertical source lens voltage, horizontal source lens voltage, extraction lens voltage, horizontal transmission lens voltage, vertical transmission lens voltage and quadrupole lens voltage so that the Ta181 signal reaches 1E -9 , resolution>4000, and at the same time correct the quadrupole efficiency coefficient to 0.8-1.1, so that the test result ratio of Ta180 and Ta181 is (0.9-1.1):(0.9-1.1), completing the calibration.

9. The trace detection method according to claim 1, wherein When the auxiliary cathode method is used for testing, the mercury cadmium telluride material is sampled in the form of a needle sample, the discharge voltage and discharge current are controlled, and the sample is cooled to -180°C with liquid nitrogen for testing.

10. Use of the trace detection method according to any one of claims 1 to 9 in the analysis and detection of trace impurities in mercury cadmium telluride semiconductive materials.

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