A method for detecting the content of a doping element in crystalline silicon at a specific site

Abstract

The application discloses a method for detecting the content of a doping element in crystalline silicon at a fixed point, and relates to the technical field of mass spectrum detection. The method combines secondary ion mass spectrum and inductively coupled plasma mass spectrum to detect the content of a doping element in crystalline silicon at a fixed ion depth. Specifically, the method detects the unit signal intensity of the crystalline silicon sample and calculates the total signal intensity by using the secondary ion mass spectrum, detects the total content of the doping element in the crystalline silicon sample by using the inductively coupled plasma mass spectrum, and calculates the content of the doping element in the crystalline silicon sample at a fixed ion depth by using the unit signal intensity u β , the total signal intensity and the total content of the doping element. The application combines the secondary ion mass spectrum and the inductively coupled plasma mass spectrum to realize quantitative and fixed-point analysis of the doping element, ensures the detection accuracy, avoids the use of standard samples in the secondary ion mass spectrum, and overcomes the use limitation of the secondary ion mass spectrum in detecting the element distribution content.

Description

Technical Field

[0001] This invention relates to the field of mass spectrometry detection technology, and in particular to a method for fixed-point detection of the content of doped elements in crystalline silicon. Background Technology

[0002] Ion implantation is a technique used to introduce dopant elements into crystalline silicon to modulate its electrical properties. Specifically, an ion beam with a certain energy is bombarded onto the surface of the crystalline silicon. After entering the silicon crystal, the ions undergo a series of collisions with silicon atoms, gradually losing energy and remaining at different depths, forming a concentration distribution curve similar to a Gaussian distribution. Therefore, the concentration of dopant elements varies at different depths, and the depth distribution and concentration of dopant elements in crystalline silicon have a decisive impact on device performance. Thus, pinpoint detection of the dopant element content at a specific ion depth in crystalline silicon is crucial for optimizing device design and manufacturing processes.

[0003] Currently, methods for detecting the elemental concentration of dopants in semiconductor materials include secondary ion mass spectrometry (SIMS) and glow discharge mass spectrometry (GDMS). However, the atomic mass ordering characteristic of the sector magnetic field detector in GDMS limits its use in rapid analysis, resulting in a longer detection time per sample. SIMS is currently the method used to detect the elemental abundance of dopants at different ion depths. SIMS works by bombarding the sample surface with primary ions to extract secondary ions, which are then analyzed by a mass spectrometer. The energy distribution and mass-to-nucleus ratio of the secondary ions reflect information about the target element, while the signal intensity over time reflects the change in the richness of the target element with depth. SIMS offers high depth resolution, enabling depth analysis of sample surfaces from micrometers to nanometers.

[0004] The journal "SIMS Quantitative Detection of Phosphorus Impurities in Silicon" (Chen Mihui et al., Electronic Science and Technology, Vol. 23, No. 9, 2010) discloses a method for SIMS detection of phosphorus content in single-crystal silicon. Specifically, it involves selecting Cs... + The sample surface is bombarded as a primary ion source, causing secondary ions to be sputtered onto the sample surface. Silicon is uniformly doped with phosphorus at a volume concentration of 1 × 10⁻⁶. 15 cm -3 Using monocrystalline silicon as a standard sample, the phosphorus content of the monocrystalline silicon was calculated by determining the relative sensitivity factor. This method relies on a standard substance with the same matrix for quantitative analysis, but such a standard substance is difficult to obtain and expensive.

[0005] Therefore, optimizing and improving the secondary ion mass spectrometry method to obtain a method for the fixed-point detection of the doping element content at a certain ion depth in crystalline silicon is of great practical significance. This method can ensure the accuracy of detection and avoid the use of standard samples. Summary of the Invention

[0006] To address the aforementioned limitations of existing technologies, the present invention aims to provide a method for targeted detection of dopant element content in crystalline silicon. This invention employs a combination of secondary ion mass spectrometry and inductively coupled plasma mass spectrometry (ICP-MS) to perform targeted detection of dopant element content at a specific ion depth in crystalline silicon containing dopant elements. Specifically, the present invention first uses secondary ion mass spectrometry to detect the unit signal intensity of the crystalline silicon sample and calculates the total signal intensity. Then, it uses ICP-MS to detect the total dopant element content in the crystalline silicon sample and utilizes the unit signal intensity u corresponding to the βth time interval. β The total signal intensity U and the total content n of doped elements in the crystalline silicon sample are used to calculate the doping element content N at a certain ion depth in the crystalline silicon sample. This invention selects a combination of secondary ion mass spectrometry and inductively coupled plasma mass spectrometry to achieve quantitative and localized analysis of doped elements. While ensuring detection accuracy, it also successfully avoids the use of standard samples in secondary ion mass spectrometry, overcoming the limitations of secondary ion mass spectrometry in detecting elemental distribution and content.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] This invention provides a method for pinpoint detection of dopant element content in crystalline silicon, comprising the following steps:

[0009] (1) Crystalline silicon containing doped elements is used as the sample to be tested. The sample to be tested is placed in a secondary ion mass spectrometer and the surface of the sample to be tested is bombarded by a primary ion beam to sputter out secondary ions.

[0010] Based on the total ion depth H of the dopants in the sample to be tested, the ion depth h of the dopants to be detected at fixed points, the sputtering rate v of the secondary ions, and the unit time t, determine the total number α per unit time and the number of unit times β corresponding to the dopants to be detected at fixed points.

[0011] The signal strength at each unit time is detected and recorded to obtain the unit signal strength u. i Where i = 1, 2, 3…α, and then using the unit signal strength u i The total signal strength U is calculated from the total number of times per unit time α.

[0012] (2) After digesting the sample to be tested, the sample solution to be tested is obtained, and the total content n of doped elements in the sample solution to be tested is detected by inductively coupled plasma mass spectrometry.

[0013] (3) The content N of doping elements at a certain ion depth in the sample to be tested is calculated according to formula (I).

[0014]

[0015] In equation (I), N is the concentration of doping elements in the sample, expressed as the number of atoms; n is the total content of doping elements in the sample, expressed as the number of atoms; U is the total signal intensity; u β Let be the unit signal strength corresponding to the βth time unit time, where β is a positive integer less than or equal to α.

[0016] Preferably, in step (1), the doping element is boron or phosphorus.

[0017] Preferably, in step (1), the crystalline silicon sample containing doped elements is prepared by ion implantation technology, and the total ion depth h of the doped elements in the sample to be tested is ≤300nm.

[0018] Preferably, in step (1), the primary ion beam is a cesium ion beam or an oxygen ion beam.

[0019] Preferably, in step (1), the sputtering rate v of the secondary ions is 0.55-0.75 nm / s.

[0020] Preferably, in step (1), the unit time t is 5-20s.

[0021] Preferably, in step (1), the formula for calculating the total number α per unit time is shown in equation (II).

[0022]

[0023] In equation (II), α is the total number per unit time; H is the total ion depth of the doped elements in the sample to be tested, in nm; v is the sputtering velocity of secondary ions, in nm / s; and t is the unit time, in s.

[0024] Preferably, in step (1), the formula for calculating the number of unit time β corresponding to the dopant element that needs to be detected at a fixed point is shown in equation (III).

[0025]

[0026] In equation (III), β is the number of unit time corresponding to the dopant element that needs to be detected at a fixed point, which is a positive integer less than or equal to α; h is the ion depth of the dopant element that needs to be detected at a fixed point, in nm; v is the sputtering velocity of the secondary ions, in nm / s; and t is the unit time, in s.

[0027] Preferably, in step (1), the formula for calculating the total signal strength U is shown in equation (IV).

[0028]

[0029] In equation (IV), α represents the total number of times per unit time; u i Let be the unit signal strength in the i-th unit time, where i = 1, 2, 3…α; U is the total signal strength.

[0030] Preferably, in step (2), the specific operation of digesting the sample to be tested is as follows: the sample to be tested and nitric acid with a concentration of 0.5 mol / L are mixed at a ratio of (0.2-0.3) g: (3-5) mL, heated at 90-110℃ for 30-60 min, cooled, and then microwave digested.

[0031] Further preferred specific parameters for microwave digestion are as follows:

[0032] Stage 1: Raise the temperature from room temperature to 110-130℃ in 4-6 minutes and hold for 1-5 minutes.

[0033] Phase 2: Heat to 150-170℃ for 4-6 minutes, and hold for 1-5 minutes.

[0034] Stage 3: Heat to 170-190℃ for 4-6 minutes and hold for 15-25 minutes.

[0035] Preferably, in step (2), the specific parameters of inductively coupled plasma mass spectrometry are: radio frequency of 1500-1600w, argon flow rate of nebulizer of 0.95-1.15mL / min, nebulization chamber temperature of 2-4℃, sampling cone and interception cone of nickel cone type, and collision reaction mode.

[0036] The beneficial effects of this invention are:

[0037] This invention employs a combination of secondary ion mass spectrometry and inductively coupled plasma mass spectrometry (ICP-MS) to perform targeted detection of the dopant element content at a specific ion depth in boron- or phosphorus-doped crystalline silicon materials. Specifically, this invention first uses secondary ion mass spectrometry to detect the unit signal intensity u of the crystalline silicon sample. i The total signal intensity U was calculated, and the total content n of doped elements in the crystalline silicon sample was detected by inductively coupled plasma mass spectrometry. The unit signal intensity u corresponding to the βth time was used. β The total signal intensity U and the total content of doped elements N in the crystalline silicon sample are used to calculate the content of doped elements N at a certain ion depth in the crystalline silicon sample.

[0038] This invention combines secondary ion mass spectrometry and inductively coupled plasma mass spectrometry to achieve quantitative and localized analysis of doping elements. While ensuring detection accuracy, it also successfully avoids the use of standard samples in secondary ion mass spectrometry, overcoming the limitations of secondary ion mass spectrometry in detecting element distribution and content. Detailed Implementation

[0039] It should be noted that the following detailed descriptions are illustrative 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.

[0040] In crystalline silicon fabricated using ion implantation, the concentration of dopant elements varies at different ion depths, and the depth distribution and concentration of dopant elements in crystalline silicon have a decisive impact on its performance. Among existing technologies, secondary ion mass spectrometry is the most commonly used method for detecting the dopant content in crystalline silicon; however, it relies on standard materials of the same matrix, which are difficult to obtain and expensive.

[0041] Based on this, the present invention provides a method for targeted detection of the dopant content in crystalline silicon. The present invention selects a crystalline silicon sample containing dopant elements as the sample to be tested, wherein the crystalline silicon sample containing dopant elements is prepared by ion implantation technology, and the ion depth of the dopant elements in the crystalline silicon sample prepared by this technology is known. First, a secondary ion mass spectrometry method is used to detect the unit signal intensity u of the crystalline silicon sample. i The total signal intensity U was calculated, and the total content n of doped elements in the crystalline silicon sample was detected by inductively coupled plasma mass spectrometry. The unit signal intensity u corresponding to the βth time was used. β The total signal intensity U and the total dopant content N in the crystalline silicon sample were used to calculate the dopant content N at different ion depths in the crystalline silicon sample. Specifically,

[0042] In the secondary ion mass spectrometry process, the sample to be tested is first placed in the secondary ion mass spectrometer, and the surface of the sample is bombarded by a primary ion beam to sputter secondary ions. By controlling the sputtering rate v and unit time t of the secondary ions in the secondary ion mass spectrometry method, combined with the total ion depth H of the dopant elements in the sample and the ion depth h of the dopant elements that need to be detected at specific points, Equation (II) is used. Japanese style (III) The total number of time intervals α and the number of unit times β corresponding to the dopant elements requiring point detection are calculated. In equations (II) and (III), rounding is done by rounding up to the nearest integer. For example, when the ion depth of the dopant element P requiring point detection in crystalline silicon is 240.0 nm, the secondary ion sputtering rate is controlled at 0.6 nm / s, and the unit time is 15 s, the result calculated using equation (III) is 26.6667. After rounding up, β = 27.

[0043] This invention achieves uniform distribution of the total ion depth in a crystalline silicon sample by controlling the sputtering rate and unit time of secondary ions, resulting in a unit ion depth. This ensures the unit ion depth is sufficiently thin, guaranteeing a uniform distribution of doped elements within the unit ion depth, and negligible loss due to the sputtering rate of secondary ions during the sputtering process. The signal intensity corresponding to each unit time is then measured, which is the unit signal intensity u. i Unit signal strength u i It can be used to characterize unit ion depth. The unit signal intensity u corresponding to α unit time... i The total signal intensity U is obtained by summing the signals. The total signal intensity can be used to characterize the total ion depth of the doped element that needs to be detected at a specific point.

[0044] The sample to be tested after secondary ion mass spectrometry is subjected to microwave digestion to obtain the sample solution. The total content n of doped elements in the crystalline silicon sample can be measured by inductively coupled plasma mass spectrometry. Since the loss of the sample to be tested during secondary ion mass spectrometry is relatively small, the loss of the sample to be tested by SIMS is ignored in this invention.

[0045] Finally, the unit quantity β corresponding to the ion depth of the doped element to be detected is taken, and the unit signal intensity u corresponding to the β-th unit time is used. β The total signal strength U and the total content of doped elements n can be used to calculate the content of doped elements N at a certain ion depth.

[0046] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0047] The experimental materials used in the embodiments of this invention are all conventional experimental materials in the art and can be purchased through commercial channels.

[0048] Example 1:

[0049] In this embodiment, crystalline silicon doped with P element is selected as the sample to be tested, and the content of doped element P at an ion depth of 110.0 nm is detected. The total ion depth H of P atoms in the sample to be tested is 200.0 nm.

[0050] (1) Place the sample to be tested in a secondary ion mass spectrometer, use a cesium ion beam as a primary ion beam to bombard the surface of the sample to be tested, sputter secondary ions, and adjust the sputtering rate of the secondary ions to 0.55 nm / s, with a unit time of 10 s;

[0051] Based on the total ion depth H of the dopant elements in the sample to be tested, the ion depth h of the dopant elements to be detected at specific points, the sputtering rate v of the secondary ions, and the unit time t, equation (II) is used. The total number of units of time is calculated as α = 37, using equation (III). The calculated number of unit time points β for the dopant elements requiring fixed-point detection is 20.

[0052] The signal strengths corresponding to these 37 time units are detected and recorded respectively, thus obtaining the unit signal strengths u1, u2, u3…u 37 , where u 20 =277.125, using the unit signal strength corresponding to the above 37 unit time, the total signal strength U = 5125.75 is calculated using formula (IV);

[0053] (2) The sample to be tested and 0.5 mol / L nitric acid were mixed at a ratio of 0.2 g: 4 mL, heated at 100 °C for 45 min, cooled, and then microwave digested to obtain the sample solution. The total content of doped elements in the sample solution, n, was determined to be 1.0144 × 10⁻⁶ using inductively coupled plasma mass spectrometry. 15 atoms, in terms of the number of atoms;

[0054] The specific parameters for microwave digestion are as follows:

[0055] Phase 1: Heat the room temperature to 120℃ for 5 minutes and hold for 3 minutes.

[0056] Phase 2: Heat to 160℃ for 5 minutes and hold for 3 minutes;

[0057] Stage 3: Heat to 180℃ for 5 minutes and hold for 20 minutes;

[0058] The specific parameters for inductively coupled plasma mass spectrometry are as follows: radio frequency of 1550 W, argon flow rate of nebulizer of 1.05 mL / min, nebulization chamber temperature of 3 °C, sampling cone and truncation cone type of pinch cone, and collision reaction mode.

[0059] (3) Based on the unit signal strength u corresponding to the βth unit time β The total signal strength U and the total content of doped elements n are determined using equation (I). Calculations show that the phosphorus (P) content at an ionic depth of 110.0 nm in crystalline silicon is 5.4844 × 10⁻⁶. 13 atoms, in terms of the number of atoms.

[0060] Example 2:

[0061] In this embodiment, crystalline silicon doped with P element is selected as the sample to be tested, and the content of doped element P at an ion depth of 240.0 nm is detected. The total ion depth H of P atoms in the sample to be tested is 300.0 nm.

[0062] (1) Place the sample to be tested in a secondary ion mass spectrometer, use a cesium ion beam as a primary ion beam to bombard the surface of the sample to be tested, sputter secondary ions, and adjust the sputtering rate of the secondary ions to 0.60 nm / s, with a unit time of 15 s;

[0063] Based on the total ion depth H of the dopant elements in the sample to be tested, the ion depth h of the dopant elements to be detected at specific points, the sputtering rate v of the secondary ions, and the unit time t, equation (II) is used. The total number of units of time is calculated as α = 34, using equation (III). The calculated number of unit time points β for the dopant elements requiring fixed-point detection is 27.

[0064] The signal strengths corresponding to these 34 time units are detected and recorded respectively, thus obtaining the unit signal strengths u1, u2, u3…u 34 , where u 27 =244, using the unit signal strength corresponding to the above 34 unit time, the total signal strength U = 9796.25 is calculated using formula (IV);

[0065] (2) The sample to be tested was digested by microwave to obtain the sample solution; the total content of doping elements in the sample solution was determined by inductively coupled plasma mass spectrometry (ICP-MS) to be 1.2211 × 10⁻⁶. 15 atoms, in terms of the number of atoms;

[0066] The specific parameters for microwave digestion and inductively coupled plasma mass spectrometry are the same as in Example 1;

[0067] (3) Based on the unit signal strength u corresponding to the βth unit time β The total signal strength U and the total content of doped elements n are determined using equation (I). Calculations show that the phosphorus (P) content at an ionic depth of 240.0 nm in crystalline silicon is 3.0415 × 10⁻⁶. 13 atoms, in terms of the number of atoms.

[0068] Example 3:

[0069] In this embodiment, crystalline silicon doped with P element is selected as the sample to be tested, and the content of doped element P at an ion depth of 180.0 nm is detected. The total ion depth H of P atoms in the sample to be tested is 200.0 nm.

[0070] (1) Place the sample to be tested in a secondary ion mass spectrometer, use a cesium ion beam as a primary ion beam to bombard the surface of the sample to be tested, sputter secondary ions, and adjust the sputtering rate of the secondary ions to 0.60 nm / s, with a unit time of 15 s;

[0071] Based on the total ion depth H of the dopant elements in the sample to be tested, the ion depth h of the dopant elements to be detected at specific points, the sputtering rate v of the secondary ions, and the unit time t, equation (II) is used. The total number of units of time is calculated as α = 23, using equation (III). The calculated number of unit time points β for the dopant elements requiring fixed-point detection is 20.

[0072] The signal strengths corresponding to these 23 time units are detected and recorded respectively, thus obtaining the unit signal strengths u1, u2, u3…u 23 , where u 20 =102.375. Using the unit signal strength corresponding to the above 23 unit time, the total signal strength U = 7653.3 is calculated using formula (IV);

[0073] (2) The sample to be tested was digested by microwave to obtain the sample solution; the total content of doping elements in the sample solution was determined by inductively coupled plasma mass spectrometry (ICP-MS) to be 1.1413 × 10⁻⁶. 15 atoms, in terms of the number of atoms;

[0074] The specific parameters for microwave digestion and inductively coupled plasma mass spectrometry are the same as in Example 1;

[0075] (3) Based on the unit signal strength u corresponding to the βth unit time β The total signal strength U and the total content of doped elements n are determined using equation (I). Calculations show that the phosphorus (P) content at an ionic depth of 180.0 nm in crystalline silicon is 1.5267 × 10⁻⁶. 13 atoms, in terms of the number of atoms.

[0076] Example 4:

[0077] In this embodiment, crystalline silicon doped with P element is selected as the test sample, and the content of doped element P at an ion depth of 280.0 nm is detected. The total ion depth H of P atoms in the test sample is 300.0 nm.

[0078] (1) Place the sample to be tested in a secondary ion mass spectrometer, use a cesium ion beam as a primary ion beam to bombard the surface of the sample to be tested, sputter secondary ions, and adjust the sputtering rate of the secondary ions to 0.70 nm / s, with a unit time of 20 s;

[0079] Based on the total ion depth H of the dopant elements in the sample to be tested, the ion depth h of the dopant elements to be detected at specific points, the sputtering rate v of the secondary ions, and the unit time t, equation (II) is used. Calculate the total number of units of time α = 22 using equation (III). The calculated number of unit time points β for the dopant elements requiring fixed-point detection is 20.

[0080] The signal strengths corresponding to these 22 unit time intervals are detected and recorded respectively, thus obtaining the unit signal strengths u1, u2, u3…u 22 , where u 20 =216.625. Using the unit signal strength corresponding to the above 22 unit time, the total signal strength U = 7598.25 is calculated using formula (IV);

[0081] (2) The sample to be tested was digested by microwave to obtain the sample solution; the total content of doping elements in the sample solution was determined by inductively coupled plasma mass spectrometry (ICP-MS) to be 1.0652 × 10⁻⁶. 15 atoms, in terms of the number of atoms;

[0082] The specific parameters for microwave digestion and inductively coupled plasma mass spectrometry are the same as in Example 1;

[0083] (3) Based on the unit signal strength u corresponding to the βth unit time β The total signal strength U and the total content of doped elements n are determined using equation (I). Calculations show that the phosphorus (P) content at an ionic depth of 280.0 nm in crystalline silicon is 3.0369 × 10⁻⁶. 13 atoms, in terms of the number of atoms.

[0084] Example 5:

[0085] In this embodiment, crystalline silicon doped with element B is selected as the sample to be tested, and the content of doped element B at an ion depth of 150.0 nm is detected. The total ion depth H of B atoms in the sample to be tested is 300.0 nm.

[0086] (1) Place the sample to be tested in a secondary ion mass spectrometer, use a cesium ion beam as a primary ion beam to bombard the surface of the sample to be tested, sputter secondary ions, and adjust the sputtering rate of the secondary ions to 0.75 nm / s, with a unit time of 5 s;

[0087] Based on the total ion depth H of the dopant elements in the sample to be tested, the ion depth h of the dopant elements to be detected at specific points, the sputtering rate v of the secondary ions, and the unit time t, equation (II) is used. The total number of units of time is calculated as α = 80, using equation (III). The calculated number of unit time points β for the dopant elements requiring fixed-point detection is 40.

[0088] The signal strengths corresponding to these 80 time units are detected and recorded respectively, thus obtaining the unit signal strengths u1, u2, u3…u 80 , where u 40 =12.780. Using the unit signal strength corresponding to the above 80 unit time, the total signal strength U = 6895.55 is calculated using formula (IV);

[0089] (2) The sample to be tested was digested by microwave to obtain the sample solution; the total content of doping elements in the sample solution was determined by inductively coupled plasma mass spectrometry (ICP-MS) to be 1.0236 × 10⁻⁶. 15 atoms, in terms of the number of atoms;

[0090] The specific parameters for microwave digestion and inductively coupled plasma mass spectrometry are the same as in Example 1;

[0091] (3) Based on the unit signal strength u corresponding to the βth unit time β The total signal strength U and the total content of doped elements n are determined using equation (I). Calculations show that the boron content at an ionic depth of 150.0 nm in crystalline silicon is 1.8971 × 10⁻⁶. 12 atoms, in terms of the number of atoms.

[0092] Experimental Example 1: Methodological Validation

[0093] The experimental example tested a boron-doped crystalline silicon standard material, which had a boron concentration distribution density of 3.90 × 10⁻⁶ at an ion depth of 120.0 nm. 19 atoms / cm 3 The concentration of element B at an ion depth of 120.0 nm in a crystalline silicon standard material doped with element B is determined using the method of this invention, based on the number of atoms. The ion depth of element B is 200 nm. The specific steps are as follows:

[0094] (1) Place the sample to be tested in a secondary ion mass spectrometer, use a cesium ion beam as a primary ion beam to bombard the surface of the sample to be tested, sputter secondary ions, and adjust the sputtering rate of the secondary ions to 0.5 nm / s, with a unit time of 10 s;

[0095] Based on the total ion depth H of the dopant elements in the sample to be tested, the ion depth h of the dopant elements to be detected at specific points, the sputtering rate v of the secondary ions, and the unit time t, equation (II) is used. The total number of units of time is calculated as α = 40, using equation (III). The calculated number of unit time units β corresponding to the dopant element requiring fixed-point detection is 24;

[0096] The signal strengths corresponding to these 40 time units are detected and recorded respectively, thus obtaining the unit signal strengths u1, u2, u3…u 40 , where u 24 =104.144. Using the unit signal strength corresponding to the above 41 unit time, the total signal strength U = 5417.67 is calculated using formula (IV);

[0097] (2) The sample to be tested was digested by microwave to obtain the sample solution; the total content of doping elements in the sample solution was determined by inductively coupled plasma mass spectrometry (ICP-MS) to be 1.045 × 10⁻⁶. 15 atoms, in terms of the number of atoms;

[0098] The specific parameters for microwave digestion and inductively coupled plasma mass spectrometry are the same as in Example 1;

[0099] (3) Based on the unit signal strength u corresponding to the βth unit time β The total signal strength U and the total content of doped elements n are determined using equation (I). Calculations show that the boron content at an ionic depth of 120.0 nm in crystalline silicon is 2.0088 × 10⁻⁶. 14 The atoms, after conversion, have a concentration distribution density of 4.0176 × 10⁻⁶. 19 atoms / cm 3 , in terms of the number of atoms.

[0100] The accuracy of the detection method of the present invention is evaluated using a relative error calculation formula, wherein... The relative error was found to be 3.08%.

[0101] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for detecting the content of a dopant element in crystalline silicon at a specific site, characterized by, The method comprises the following steps: (1) taking a crystal silicon sample containing a doping element as a sample to be tested, placing the sample to be tested in a secondary ion mass spectrometer, and using a primary ion beam to bombard the surface of the sample to be tested to sputter secondary ions; According to the total ion depth H of the doping element in the sample to be tested, the ion depth h of the doping element to be detected, the sputtering speed v of the secondary ions, and the unit time t, the total number per unit time α and the unit time number β corresponding to the doping element to be detected are determined. The signal intensity corresponding to each unit time is detected and recorded, i.e. the unit signal intensity u is obtained i wherein i = 1, 2, 3…α, and the total signal intensity U is calculated using the unit signal intensity u i and the total number of unit times α. The total number of units per time α is calculated by the following formula: , In the formula, α is the total number per unit time; H is the total ion depth of the doping element in the sample to be tested, and the unit is nm; v is the sputtering speed of the secondary ions, and the unit is nm / s; t is the unit time, and the unit is s; The unit time number β of the doped element corresponding to the fixed-point detection is: , In the formula, β is the unit time number corresponding to the doping element to be detected, which is a positive integer less than or equal to α; h is the ion depth of the doping element to be detected, and the unit is nm; v is the sputtering speed of the secondary ions, and the unit is nm / s; t is the unit time, and the unit is s; (2) after the sample to be tested is digested, a sample solution is obtained, and the total content n of the doping element in the sample solution is detected by inductively coupled plasma mass spectrometry; (3) the content N of the doping element at a certain ion depth in the sample to be tested is calculated according to formula (I), Formula (I), In formula (I), N is the concentration of the doping element in the sample to be tested, in terms of atom number; n is the total content of the doping element in the sample to be tested, in terms of atom number; U is the total signal intensity; u β is the unit signal intensity corresponding to the βth unit time, wherein β is a positive integer less than or equal to α.

2. The method for detecting the content of a dopant element in crystalline silicon at a specific site according to claim 1, wherein In step (1), the doping element is boron or phosphorus.

3. The method for detecting the content of a dopant element in crystalline silicon at a specific site according to claim 1, wherein In step (1), the crystal silicon sample containing a doping element is prepared by ion implantation technology, and the total ion depth H of the doping element in the sample to be tested is ≤300 nm.

4. The method for detecting the content of a dopant element in crystalline silicon at a specific site according to claim 1, wherein In step (1), the primary ion beam is a cesium ion beam or an oxygen ion beam.

5. The method for detecting the content of a dopant element in crystalline silicon at a site according to claim 1, wherein In step (1), the sputtering speed v of the secondary ions is 0.55-0.75 nm / s.

6. The method for detecting the content of a dopant element in crystalline silicon at a specific site according to claim 1, wherein In step (1), the unit time t is 5-20 s.

7. The method for detecting the content of a dopant element in crystalline silicon at a site according to claim 1, wherein In step (1), the formula for calculating the total signal intensity U is shown in formula (II), Equation (II), In formula (II), α is the total number per unit time; u i Unit signal intensity for the ith unit time, where i = 1, 2, 3...a; U is the total signal intensity.

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