Method for fixed-point detection of doped element content in crystalline silicon

Abstract

The invention discloses a method for fixed-point detection of the content of doped elements in crystalline silicon, and relates to the technical field of mass spectrometric detection. Secondary ion mass spectrometry and inductively coupled plasma mass spectrometry are combined to carry out fixed-point detection on the content of the doped elements in a certain ion depth in crystalline silicon containing the doped elements. Specifically, secondary ion mass spectrometry is adopted to detect the unit signal intensity of a crystalline silicon sample and calculate the total signal intensity, inductively coupled plasma mass spectrometry is adopted to detect the total content of doped elements in the crystalline silicon sample, and the unit signal intensity u [beta], the total signal intensity and the total content of the doped elements are utilized to determine the content of the doped elements in the crystalline silicon sample. And calculating to obtain the doped element content in the crystalline silicon sample under a certain ion depth. According to the method, the secondary ion mass spectrometry and the inductively coupled plasma mass spectrometry are combined to realize quantitative fixed-point analysis of the doped elements, so that the detection accuracy is ensured, the use of a standard sample in the secondary ion mass spectrometry is avoided, and the use limitation of the standard sample in detection of the element distribution content is overcome.

Description

Technical Field

[0001] The invention relates to the technical field of mass spectrometry detection, and in particular to a method for fixed-point detection of doping element content in crystalline silicon. Background Art

[0002] Ion implantation is a technology that can be used to introduce doping elements into crystalline silicon to adjust the electrical properties of crystalline silicon. Specifically, an ion beam with a certain energy is bombarded onto the surface of crystalline silicon. After entering the silicon crystal, the ions will undergo a series of collisions with silicon atoms, gradually lose energy and stay at different depths, forming a concentration distribution curve similar to a Gaussian distribution. It can be seen that the concentration of doping elements is different at different depths, and the depth distribution and element concentration of doping elements in crystalline silicon have a decisive influence on the performance of the device. Therefore, fixed-point detection of the element content of doping elements at a certain ion depth in crystalline silicon plays a vital role in optimizing device design and manufacturing processes.

[0003] At present, the methods used to detect the elemental concentration of doping elements in semiconductor materials include secondary ion mass spectrometry (SIMS) and glow discharge mass spectrometry (GDMS). Among them, the sector magnetic field detector of glow discharge mass spectrometry is limited in rapid analysis due to the characteristics of atomic mass order, and the detection time of each sample is relatively long. SIMS is a method currently used to detect the elemental content of doping elements at different ion depths. SIMS bombards the sample surface with primary ions, induces secondary ions, and analyzes them through a mass spectrometer. The energy distribution and nucleus-mass ratio of secondary ions reflect the information of the target elements, and the curve of signal intensity change with time reflects the change of target element abundance with depth. It has a high depth resolution and can perform micron to nanometer depth analysis on the sample surface.

[0004] The journal "SIMS Quantitative Detection of Phosphorus Impurities in Silicon" (Chen Mihui et al., Electronic Technology, Vol. 23, No. 9, 2010) discloses a method for detecting the element content of phosphorus in single crystal silicon by SIMS. Specifically, Cs + As a primary ion source, the sample surface is bombarded to form secondary ions by sputtering. The silicon is uniformly doped with phosphorus and the body concentration of phosphorus is 1×10 15 cm -3 The single crystal silicon of is used as the standard sample, and the phosphorus content of the single crystal silicon is calculated by calculating the relative sensitivity factor. The above method relies on the standard material of the same matrix during the quantitative analysis process, but the standard material is not easy to obtain and is expensive.

[0005] Therefore, it is of practical significance to optimize and improve the secondary ion mass spectrometry method to obtain a method for fixed-point detection of the doping element content at a certain ion depth in crystalline silicon, which can not only ensure the accuracy of detection but also avoid the use of standard samples. Summary of the invention

[0006] In view of the above-mentioned prior art, the purpose of the present invention is to provide a method for fixed-point detection of the content of doping elements in crystalline silicon. The present invention uses a combination of secondary ion mass spectrometry and inductively coupled plasma mass spectrometry to perform fixed-point detection of the content of doping elements in a certain ion depth in crystalline silicon containing doping 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, and uses inductively coupled plasma mass spectrometry to detect the total content of doping elements in the crystalline silicon sample, and uses the unit signal intensity u corresponding to the βth unit time. β , total signal intensity U and total content n of doping elements in the crystalline silicon sample, and calculate the doping element content N at a certain ion depth in the crystalline silicon sample. The present invention selects secondary ion mass spectrometry and inductively coupled plasma mass spectrometry to achieve quantitative fixed-point analysis of doping elements. On the basis of ensuring detection accuracy, it also successfully avoids the use of standard samples in secondary ion mass spectrometry, and overcomes the limitations of secondary ion mass spectrometry in detecting element distribution content.

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

[0008] The present invention provides a method for fixed-point detection of the content of doping elements in crystalline silicon, comprising the following steps:

[0009] (1) Using crystalline silicon containing doped elements as a sample to be tested, placing the sample to be tested in a secondary ion mass spectrometer, bombarding the surface of the sample to be tested with a primary ion beam, and sputtering out secondary ions;

[0010] According to the total ion depth H of the doping elements in the sample to be tested, the ion depth h of the doping elements to be detected at a fixed point, the sputtering speed v of the secondary ions and the unit time t, the total number per unit time α and the number per unit time β corresponding to the doping elements to be detected at a fixed point are determined;

[0011] Detect the signal strength corresponding to each unit time and record it, and get 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 by the total number α per unit time;

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

[0013] (3) According to formula (I), the doping element content N at a certain ion depth in the sample to be tested is calculated,

[0014]

[0015] In formula (I), N is the concentration of doping elements in the sample to be tested, in terms of the number of atoms; n is the total content of doping elements in the sample to be tested, in terms of the number of atoms; U is the total signal intensity; u β is the unit signal strength corresponding to the βth 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 the doping element is obtained by ion implantation technology, and the total ion depth h of the doping element 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 speed 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 calculation formula for the total number α per unit time is as shown in formula (II),

[0022]

[0023] Formula (II), α is the total number per unit time; H is the total ion depth of the doping element in the sample to be tested, in nm; v is the sputtering speed of the secondary ions, in nm / s; t is the unit time, in s.

[0024] Preferably, in step (1), the calculation formula for the unit time number β corresponding to the doping element to be detected at a fixed point is as shown in formula (III),

[0025]

[0026] In formula (III), β is the unit time corresponding to the doping 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 doping element that needs to be detected at a fixed point, in nm; v is the sputtering speed of the secondary ions, in nm / s; t is the unit time, in s.

[0027] Preferably, in step (1), the calculation formula of the total signal intensity U is as shown in formula (IV),

[0028]

[0029] In formula (IV), α is the total number per unit time; u i is the unit signal strength of 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: mixing the sample to be tested and 0.5 mol / L nitric acid at a ratio of (0.2-0.3) g: (3-5) mL, heating at 90-110° C. for 30-60 min, and then cooling and performing microwave digestion.

[0031] Further preferably, the specific parameters of microwave digestion are as follows:

[0032] Stage 1: Heating from room temperature to 110-130°C, the heating time is 4-6 minutes, and the insulation time is 1-5 minutes;

[0033] Stage 2: Heating to 150-170°C, heating time is 4-6 minutes, and keeping time is 1-5 minutes;

[0034] Stage 3: Heating to 170-190°C, heating time is 4-6 minutes, and keeping time is 15-25 minutes.

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

[0036] Beneficial effects of the present invention:

[0037] The present invention uses secondary ion mass spectrometry and inductively coupled plasma mass spectrometry to perform fixed-point detection of the doping element content in a certain ion depth in a crystalline silicon material doped with boron or phosphorus. Specifically, the present 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 is calculated, and the total content n of doping elements in the crystalline silicon sample is detected by inductively coupled plasma mass spectrometry. The unit signal intensity u corresponding to the βth unit time is used β , total signal intensity U and the total content N of doping elements in the crystalline silicon sample, and calculate the doping element content N at a certain ion depth in the crystalline silicon sample.

[0038] The present invention selects secondary ion mass spectrometry and inductively coupled plasma mass spectrometry to achieve quantitative and fixed-point analysis of doping elements. On the basis of ensuring detection accuracy, it also successfully avoids the use of standard samples in secondary ion mass spectrometry, and overcomes the limitations of secondary ion mass spectrometry in detecting element distribution content. DETAILED DESCRIPTION

[0039] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0040] In crystalline silicon produced by ion implantation technology, the concentration of doping elements is different at different ion depths. The depth distribution and element concentration of doping elements in crystalline silicon have a decisive influence on its performance. In the prior art, secondary ion mass spectrometry is the most commonly used method to detect the content of doping elements in crystalline silicon, but it relies on standard substances of the same matrix, which are difficult to obtain and expensive.

[0041] Based on this, the present invention provides a method for fixed-point detection of the content of doping elements in crystalline silicon. The present invention selects a crystalline silicon sample containing doping elements as a sample to be tested, wherein the crystalline silicon sample containing doping elements is prepared by ion implantation technology, and the ion depth of the doping elements in the crystalline silicon sample prepared by this technology is known. Secondary ion mass spectrometry is first used to detect the unit signal intensity u of the crystalline silicon sample. i The total signal intensity U is calculated, and the total content n of doping elements in the crystalline silicon sample is detected by inductively coupled plasma mass spectrometry. The unit signal intensity u corresponding to the βth unit time is used β , the total signal intensity U and the total content N of the doping elements in the crystalline silicon sample, and calculate the content N of the doping elements 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 to be tested is bombarded with a primary ion beam to sputter out secondary ions. By controlling the sputtering speed v and unit time t of the secondary ions in the secondary ion mass spectrometry, combined with the total ion depth H of the doping element in the sample to be tested and the ion depth h of the doping element to be detected at a fixed point, the formula (II) is used: And formula (III) The total number of time intervals α and the number of unit times β corresponding to the doping element to be detected at a fixed point are calculated. In formula (II) and formula (III), rounding is rounding up to the nearest integer, that is, rounding the calculation result up to the nearest integer. For example, when the ion depth of the doping element P to be detected at a fixed point in crystalline silicon is 240.0nm, the secondary ion sputtering speed is controlled to be 0.6nm / s, and the unit time is 15s, 26.6667 is calculated using formula (III). After rounding up, β=27.

[0043] The present invention can achieve the equidivision of the total ion depth of the crystalline silicon sample by controlling the sputtering speed and unit time of the secondary ions, and obtain the unit ion depth, so as to ensure that the unit ion depth after equidivision is thin enough, thereby ensuring that the doping elements corresponding to the unit ion depth are evenly distributed and the loss of the secondary ion sputtering speed during the sputtering process can be ignored. Then the signal intensity corresponding to each unit time is detected, which is the unit signal intensity u i , unit signal strength u i It can be used to characterize the unit ion depth. The unit signal intensity u corresponding to α unit time i The total signal intensity U is obtained by adding them up. The total signal intensity can be used to characterize the total ion depth of the doping element that needs to be detected at a fixed point.

[0044] The sample to be tested after secondary ion mass spectrometry is subjected to microwave digestion to obtain a sample solution to be tested, and the total content n of the doping elements in the crystalline silicon sample can be measured using inductively coupled plasma mass spectrometry. Among them, the loss of the sample to be tested during the secondary ion mass spectrometry process is relatively small. Therefore, the loss of the sample to be tested due to SIMS is ignored in the present invention.

[0045] Finally, take the unit number β corresponding to the ion depth of the doping element to be detected at the fixed point, and use the unit signal intensity u corresponding to the βth unit time measured β , the total signal intensity U and the total content n of the doping element, the doping element content N at a certain ion depth can be calculated.

[0046] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

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

[0048] Embodiment 1:

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

[0050] (1) The sample to be tested is placed in a secondary ion mass spectrometer, and a cesium ion beam is used as a primary ion beam to bombard the surface of the sample to be tested, and secondary ions are sputtered. The sputtering speed of the secondary ions is adjusted to 0.55 nm / s, and the unit time is 10 s;

[0051] 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 at a fixed point, the sputtering speed v of the secondary ions and the unit time t, the formula (II) is used: Calculate the total number of unit time α=37, using formula (III) The calculated unit time number β corresponding to the doping element to be detected at a fixed point is 20;

[0052] Detect and record the signal strengths corresponding to these 37 unit times respectively, and obtain 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 times, 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 and heated at 100°C for 45 min. After cooling, microwave digestion was performed to obtain the sample solution to be tested. The total content of doping elements in the sample solution to be tested was detected by inductively coupled plasma mass spectrometry, and the total content n was 1.0144×10 15 atoms, measured by the number of atoms;

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

[0055] Stage 1: The room temperature is raised to 120°C, the heating time is 5 minutes, and the heat preservation time is 3 minutes;

[0056] Stage 2: Heating to 160°C for 5 minutes and keeping warm for 3 minutes;

[0057] Stage 3: Heating to 180°C for 5 minutes and keeping warm for 20 minutes;

[0058] The specific parameters of the inductively coupled plasma mass spectrometry were as follows: the radio frequency was 1550 w, the nebulizer argon gas flow rate was 1.05 mL / min, the nebulizer temperature was 3 °C, the sampling cone and skimmer cone types were pinch cones, and the collision reaction mode was used;

[0059] (3) According to the unit signal strength u corresponding to the βth unit time β , the total signal intensity U and the total content n of the doping element, using formula (I) According to calculation, the P content at the 110.0nm ion depth in crystalline silicon is 5.4844×10 13 atoms, measured in terms of the number of atoms.

[0060] Embodiment 2:

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

[0062] (1) The sample to be tested is placed in a secondary ion mass spectrometer, and a cesium ion beam is used as a primary ion beam to bombard the surface of the sample to be tested, and secondary ions are sputtered. The sputtering speed of the secondary ions is adjusted to 0.60 nm / s, and the unit time is 15 s;

[0063] 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 at a fixed point, the sputtering speed v of the secondary ions and the unit time t, the formula (II) is used: Calculate the total number of unit time α=34, using formula (III) The calculated unit time number β corresponding to the doping element to be detected at a fixed point is 27;

[0064] Detect and record the signal strengths corresponding to these 34 unit times respectively, and obtain the unit signal strengths u1, u2, u3…u 34 , where u 27 =244, using the unit signal strength corresponding to the above 34 unit times, 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 a sample solution to be tested; the total content of doping elements in the sample solution to be tested was detected by inductively coupled plasma mass spectrometry, and n was 1.2211×10 15 atoms, measured by the number of atoms;

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

[0067] (3) According to the unit signal strength u corresponding to the βth unit time β , the total signal intensity U and the total content n of the doping element, using formula (I) According to calculation, the P content at the 240.0nm ion depth in crystalline silicon is 3.0415×10 13 atoms, measured in terms of the number of atoms.

[0068] Embodiment 3:

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

[0070] (1) The sample to be tested is placed in a secondary ion mass spectrometer, and a cesium ion beam is used as a primary ion beam to bombard the surface of the sample to be tested, and secondary ions are sputtered. The sputtering speed of the secondary ions is adjusted to 0.60 nm / s, and the unit time is 15 s;

[0071] 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 at a fixed point, the sputtering speed v of the secondary ions and the unit time t, the formula (II) is used: Calculate the total number of unit time α=23, using formula (III) The calculated unit time number β corresponding to the doping element to be detected at a fixed point is 20;

[0072] Detect and record the signal strengths corresponding to these 23 unit times respectively, and obtain 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 times, 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 a sample solution to be tested; the total content of doping elements in the sample solution to be tested was detected by inductively coupled plasma mass spectrometry, and the total content n was 1.1413×10 15 atoms, measured by the number of atoms;

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

[0075] (3) According to the unit signal strength u corresponding to the βth unit time β , the total signal intensity U and the total content n of the doping element, using formula (I) According to calculation, the P content at the 180.0nm ion depth in crystalline silicon is 1.5267×10 13 atoms, measured in terms of the number of atoms.

[0076] Embodiment 4:

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

[0078] (1) The sample to be tested is placed in a secondary ion mass spectrometer, and a cesium ion beam is used as a primary ion beam to bombard the surface of the sample to be tested, and secondary ions are sputtered. The sputtering speed of the secondary ions is adjusted to 0.70 nm / s, and the unit time is 20 s;

[0079] 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 at a fixed point, the sputtering speed v of the secondary ions and the unit time t, the formula (II) is used: Calculate the total number of unit time α=22, using formula (III) The calculated unit time number β corresponding to the doping element to be detected at a fixed point is 20;

[0080] Detect and record the signal strengths corresponding to these 22 unit times respectively, and obtain 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 times, 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 a sample solution to be tested; the total content of doping elements in the sample solution to be tested was detected by inductively coupled plasma mass spectrometry, and the total content n was 1.0652×10 15 atoms, measured by the number of atoms;

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

[0083] (3) According to the unit signal strength u corresponding to the βth unit time β , the total signal intensity U and the total content n of the doping element, using formula (I) According to calculation, the P content at the 280.0nm ion depth in crystalline silicon is 3.0369×10 13 atoms, measured in terms of the number of atoms.

[0084] Embodiment 5:

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

[0086] (1) placing the sample to be tested in a secondary ion mass spectrometer, using a cesium ion beam as a primary ion beam to bombard the surface of the sample to be tested, sputtering secondary ions, and adjusting the sputtering speed of the secondary ions to be 0.75 nm / s, and the unit time to be 5 s;

[0087] 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 at a fixed point, the sputtering speed v of the secondary ions and the unit time t, the formula (II) is used: Calculate the total number of unit time α = 80, using formula (III) The calculated unit time number β corresponding to the doping element to be detected at a fixed point is 40;

[0088] Detect and record the signal strengths corresponding to these 80 unit times respectively, and obtain 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 times, 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 a sample solution to be tested; the total content of doping elements in the sample solution to be tested was detected by inductively coupled plasma mass spectrometry, and the total content n was 1.0236×10 15 atoms, measured by the number of atoms;

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

[0091] (3) According to the unit signal strength u corresponding to the βth unit time β , the total signal intensity U and the total content n of the doping element, using formula (I) Calculation shows that the B content at 150.0nm ion depth in crystalline silicon is 1.8971×10 12 atoms, measured in terms of the number of atoms.

[0092] Test Example 1: Methodology Validation

[0093] The test object of the test example is a crystalline silicon standard material doped with element B. The concentration distribution density of element B in the standard material at an ion depth of 120.0 nm is 3.90×10 19 atoms / cm 3 , in terms of the number of atoms, the concentration of the B element at an ion depth of 120.0 nm in the crystalline silicon standard material doped with the B element is detected at a fixed point using the method of the present invention, wherein the ion depth of the B element is 200 nm. The specific steps are:

[0094] (1) The sample to be tested is placed in a secondary ion mass spectrometer, and a cesium ion beam is used as a primary ion beam to bombard the surface of the sample to be tested, and secondary ions are sputtered. The sputtering speed of the secondary ions is adjusted to 0.5 nm / s, and the unit time is 10 s;

[0095] 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 at a fixed point, the sputtering speed v of the secondary ions and the unit time t, the formula (II) is used: Calculate the total number of unit time α = 40, using formula (III) The calculated unit time number β corresponding to the doping element to be detected at a fixed point is 24;

[0096] Detect and record the signal strengths corresponding to these 40 unit times respectively, and obtain 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 times, 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 a sample solution to be tested; the total content of doping elements in the sample solution to be tested was detected by inductively coupled plasma mass spectrometry, and n was 1.045×10 15 atoms, measured by the number of atoms;

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

[0099] (3) According to the unit signal strength u corresponding to the βth unit time β , the total signal intensity U and the total content n of the doping element, using formula (I) Calculation shows that the B content at 120.0nm ion depth in crystalline silicon is 2.0088×10 14 atoms, after conversion, the concentration distribution density is 4.0176×10 19 atoms / cm 3 , measured in 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 is 3.08%.

[0101] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for fixed-point detection of doping element content in crystalline silicon, characterized in that: The following steps are involved: (1) Using crystalline silicon containing doped elements as a sample to be tested, placing the sample to be tested in a secondary ion mass spectrometer, bombarding the surface of the sample to be tested with a primary ion beam, and sputtering out secondary ions; According to the total ion depth H of the doping elements in the sample to be tested, the ion depth h of the doping elements to be detected at a fixed point, the sputtering speed v of the secondary ions and the unit time t, the total number per unit time α and the number per unit time β corresponding to the doping elements to be detected at a fixed point are determined; Detect and record the signal strength corresponding to each unit time, that is, 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 by the total number α per unit time; (2) After digesting the sample to be tested, a sample solution to be tested is obtained, and the total content n of the doping element in the sample solution to be tested is detected by inductively coupled plasma mass spectrometry; (3) According to formula (I), the doping element content N at a certain ion depth in the sample to be tested is calculated, In formula (I), N is the concentration of doping elements in the sample to be tested, in terms of the number of atoms; n is the total content of doping elements in the sample to be tested, in terms of the number of atoms; U is the total signal intensity; u β is the unit signal strength corresponding to the βth unit time, where β is a positive integer less than or equal to α.

2. The method for fixed-point detection of doping element content in crystalline silicon according to claim 1, characterized in that: In step (1), the doping element is boron or phosphorus.

3. The method for fixed-point detection of doping element content in crystalline silicon according to claim 1, characterized in that: In step (1), the crystalline silicon sample containing doping elements is prepared by ion implantation technology, and the total ion depth H of the doping elements in the sample to be tested is ≤300nm.

4. The method for fixed-point detection of doping element content in crystalline silicon according to claim 1, characterized in that: In step (1), the primary ion beam is a cesium ion beam or an oxygen ion beam.

5. The method for fixed-point detection of doping element content in crystalline silicon according to claim 1, characterized in that: In step (1), the sputtering speed v of the secondary ions is 0.55-0.75 nm / s.

6. The method for fixed-point detection of doping element content in crystalline silicon according to claim 1, characterized in that: In step (1), the unit time t is 5-20s.

7. The method for fixed-point detection of doping element content in crystalline silicon according to claim 1, characterized in that: In step (1), the calculation formula of the total number α per unit time is shown in formula (II), Formula (II), α is the total number per unit time; H is the total ion depth of the doping element in the sample to be tested, in nm; v is the sputtering speed of the secondary ions, in nm / s; t is the unit time, in s.

8. The method for fixed-point detection of doping element content in crystalline silicon according to claim 1, characterized in that: In step (1), the calculation formula of the unit time number β corresponding to the doping element to be detected at a fixed point is shown in formula (III), In formula (III), β is the unit time corresponding to the doping 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 doping element that needs to be detected at a fixed point, in nm; v is the sputtering speed of the secondary ions, in nm / s; t is the unit time, in s.

9. The method for fixed-point detection of doping element content in crystalline silicon according to claim 1, characterized in that: In step (1), the calculation formula of the total signal strength U is shown in formula (IV), In formula (IV), α is the total number per unit time; u i is the unit signal strength of the i-th unit time, where i=1, 2, 3…α; U is the total signal strength.

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