Method for detecting doping elements of rough surface semiconductor material and application

Abstract

The present application relates to material detection technical field, especially to IPC G01N27 field, further, it relates to a kind of rough surface semiconductor material doping element detection method and application.It includes the following steps: S1, selecting ion source;S2, sample is placed in the sample chamber of secondary ion mass spectrometer, and vacuumizing;S3, primary light path adjustment;S4, secondary light path adjustment;S5, setting test condition;S6, test sample.In the present application, by primary light path adjustment and secondary light path adjustment, beam spot has good focusing, improves the sensitivity, accuracy of detection result, and improves the precision of detection result.

Description

Technical Field

[0001] This invention relates to the field of materials testing technology, particularly to the field of IPC G01N27, and further to a method and application for detecting doped elements in rough-surface semiconductor materials. Background Technology

[0002] Secondary ion mass spectrometry has a low detection limit; for common semiconductor dopants such as boron and phosphorus, the detection limit can be below 10. 14 atm / cm 3 However, secondary ion mass spectrometry (DIMS) has high requirements for sample preparation. For quantitative analysis, it can typically only be performed on smooth, flat sample surfaces, with a roughness preferably less than 20 nm. Currently available commercial standards are all smooth surfaces, unsuitable for rough or textured surfaces. Furthermore, the angle between the rough surface and the ion beam causes uneven distribution of the test signal, resulting in poor data repeatability. Currently, there is no existing technology for using secondary ion mass spectrometry to detect dopant elements in materials with rough or textured surfaces. Summary of the Invention

[0003] The purpose of this invention is to provide a method for detecting doping elements in rough-surface semiconductor materials, providing a powerful tool for measuring doping elements on the textured surface of solar cells and for testing other semiconductor materials.

[0004] To address the aforementioned technical problems, the first aspect of this invention provides a method for detecting the boron doping concentration of a silicon-based textured surface, comprising the following steps:

[0005] S1. Select the ion source;

[0006] S2. Place the sample in the sample chamber of the secondary ion mass spectrometer and evacuate it.

[0007] S3, First optical path adjustment;

[0008] S4. Secondary optical path adjustment;

[0009] S5. Set test conditions;

[0010] S6, Test Sample.

[0011] In some preferred embodiments, the ion source in S1 is a Cs source or an O source.

[0012] In some preferred embodiments, the phosphorus doping concentration of the rough surface semiconductor material is tested, and the ion source in S1 is a Cs source.

[0013] Preferably, the Cs source is 133Cs. + .

[0014] In some preferred embodiments, the boron doping concentration of the rough surface semiconductor material is tested, and the ion source in S1 is an O source.

[0015] Preferably, the O source is 16 O - , 16 O2 - Any one of them.

[0016] In some preferred embodiments, the sample is a textured silicon-based material.

[0017] Preferably, the sample is a textured silicon wafer.

[0018] Preferably, the textured silicon wafer is an acid-textured silicon wafer.

[0019] In some preferred embodiments, the optical path adjustment in S3 includes the following steps:

[0020] (1) Adjust the beam intensity;

[0021] (2) Adjust the centers of the two beam spots to coincide;

[0022] (3) Eliminate dispersion or center the spot size within the dispersion;

[0023] (4) Adjust the preset value of the aperture of the transmission lens L4, and repeat (2) to keep the center of the beam spot unchanged;

[0024] (5) Adjust the preset value of the ion source pore size to maximize the beam intensity;

[0025] (6) Adjust the beam spot position to center the beam spot and turn on the grating.

[0026] Preferably, the specific method of (1) in S3 is as follows: turn off the light source, adjust the beam intensity to 40~50nA by changing the transmission lens L2, then change the X and Y direction values ​​of the offset plate to adjust the beam intensity to 90~100nA; then alternately change the transmission lens L2 and the offset plate to adjust the beam intensity to 150~170nA.

[0027] Preferably, the transmission lens L2 and the offset plate are alternately changed to adjust the beam intensity to 160 nA.

[0028] Preferably, the specific method of (2) in S3 is as follows: adjust the beam intensity to 10~20nA by changing the transmission lens L2; ​​turn off the grating and adjust the transmission lens L4 to focus the beam spot; increase and decrease the transmission lens L4 respectively to adjust two unfocused beam spots; and make the centers of the two unfocused beam spots coincide by changing the X and Y direction values ​​of the aperture of the transmission lens L4.

[0029] Preferably, the aperture value of the transmission lens L4 in S3 (4) is preset to 100~750.

[0030] Preferably, the preset values ​​of the aperture of the transmission lens L4 in S3 (4) are 750, 300, 200, and 100, respectively.

[0031] Preferably, the preset value of the ion source pore size in S3 (5) is 100~2000.

[0032] Preferably, the pore size of the ion source in S3 (5) is set to 2000, 750, 400, 300, and 100, respectively.

[0033] In some preferred embodiments, the secondary optical path adjustment in S4 includes the following steps:

[0034] (1) Make the center of the image and the spot at the same point;

[0035] (2) In slit mode, change the paired lens and adjust the electrostatic analyzer and mass number so that the center of the image remains unchanged when the paired electron microscope is changed;

[0036] (3) Adjust the exit slit;

[0037] (4) Adjust the entrance slit;

[0038] (5) Obtain the comparison gap value;

[0039] (6) Adjust the field gap value.

[0040] Preferably, the specific method in S4 (1) is: adjusting the deflection plate and mass number so that when the image changes the transmission lens L1, the center of the image and the beam spot are at the same point.

[0041] Preferably, the specific method of S4 (3) is as follows: in slit mode, the exit slit is closed to 3000~5000µm, and the edge of the exit slit is made clear by adjusting the transmission lens L1. Then the exit slit is opened and restored to 300~500µm.

[0042] Preferably, the specific method of (3) in S4 is as follows: in slit mode, the exit slit is closed to 4000µm, the edge of the exit slit is made clear by adjusting the transmission lens L1, and then the exit slit is opened to restore it to 400µm.

[0043] Preferably, the specific method of S4 (4) is as follows: in slit mode, close the entrance slit to 20~70µm, adjust the edge of the entrance slit to be clear, and finally close the entrance slit again, and adjust the edges of the exit slit and the entrance slit to be parallel; open the exit slit and the entrance slit.

[0044] Preferably, the entrance slit is closed to 60µm.

[0045] Preferably, when testing the phosphorus doping concentration of silicon-based textured surfaces, the outgoing slit is closed to 4000µm; at the same time, the incoming slit is closed to 30µm.

[0046] Preferably, the specific method of step (5) in S4 is as follows: Select a preset value for the scanning range of 130~150µm; set the transfer lens L1 and transfer lens L2 to 0; change the values ​​of the X and Y directions of the contrast slit transfer plate so that the beam position remains unchanged when the value of the transfer lens L1 is changed; after the contrast slit transfer plate gap is adjusted, set the transfer lens L1 to 0; change the values ​​of the X and Y directions of the contrast slit so that the beam position remains unchanged when the value of the transfer lens L2 is changed; remember the changed values ​​of the contrast slit transfer plate, read the unsaved preset value for the scanning range, and input the recorded values ​​of the contrast slit transfer plate; select different preset values ​​for the contrast slit (50~400), repeat step 5 to obtain the correct contrast slit value, and save it in the scanning menu.

[0047] Preferably, the preset value for the scanning range is 150µm.

[0048] Preferably, the preset values ​​for the comparison gap are 400, 150, 100, and 50.

[0049] Preferably, the specific method of S4 (6) is as follows: turn off the grating, adjust the beam spot position to center the beam spot; select different preset values ​​of field gap (100~2000), and adjust the field gaps X and Y to center the field gap.

[0050] Preferably, the preset values ​​for the field gap are 1800, 750, 400, and 100.

[0051] In this invention, primary and secondary optical path adjustments enable the beam spot to achieve good focusing, thereby improving the sensitivity and accuracy of the detection results while also enhancing the precision of the results. During the experiment, the applicant discovered that, particularly when adjusting the beam current intensity to 160 nA during the primary optical path adjustment, excessively large beam spot diameters can be avoided from affecting depth analysis. Furthermore, controlling the exit and entrance slit values ​​to 4000 µm and 30 µm respectively during the secondary optical path adjustment improves signal strength while maintaining quality resolution. Maintaining quality resolution avoids the reliability of measurement results due to multiple peak superposition, and in particular, improves the detection results of phosphorus doping concentration on silicon-based textured surfaces. The applicant hypothesizes that since 30Si+H and P have similar mass numbers, low mass resolution can lead to multiple peaks overlapping, affecting the detection results of phosphorus doping concentration on silicon-based textured surfaces. Parameters under these conditions provide good beam focusing, have minimal impact on the shape of sputtering pits during sputtering, and achieve uniform etching, thereby improving the sensitivity and accuracy of phosphorus doping concentration detection without affecting imaging quality. Furthermore, parameters under these conditions are more suitable for testing phosphorus doping concentration on silicon-based textured surfaces with different roughnesses, avoiding significant differences in depth during bombardment, thus improving the precision of phosphorus doping concentration detection results on silicon-based textured surfaces.

[0052] In some preferred embodiments, the test conditions in S5 are as follows: beam current intensity of 100~150nA, scanning range of 130~150µm, ion source aperture of 1500~3000, L4 transmission lens aperture of 300~800, contrast slit of 300~500, field slit of 300~500, grating of 70~120, and electron gate of 70~90%.

[0053] Preferably, the test conditions in S5 are: beam current intensity of 130 nA, scanning range of 150 µm, ion source aperture of 2000, L4 transmission lens aperture of 750, contrast slit of 400, field slit of 400, grating of 100, and electron gate of 80%.

[0054] The second aspect of the present invention provides an application of a method for detecting doped elements in a rough surface semiconductor material, which is applied to the detection of boron and phosphorus doping concentrations on a silicon-based textured surface.

[0055] Beneficial effects: This invention achieves good beam focusing through primary and secondary optical path adjustments, improving both the sensitivity and accuracy of the detection results while enhancing their precision. Under specific conditions, the parameters exhibit good beam focusing, minimizing the impact on the shape of the sputtering pit during sputtering, thus achieving uniform etching. This, in turn, improves the sensitivity and accuracy of phosphorus doping concentration detection without affecting imaging quality. Furthermore, it is more suitable for testing phosphorus doping concentration on silicon-based textured surfaces with varying roughness, avoiding significant differences in depth during bombardment and thereby improving the precision of phosphorus doping concentration detection results on silicon-based textured surfaces. Attached Figure Description

[0056] Figure 1 This is a boron depth distribution map of the sample measured in Example 1 of the present invention.

[0057] Figure 2 This is a phosphorus depth distribution map of the sample measured in Example 2 of the present invention. Detailed Implementation

[0058] Example 1

[0059] Example 1 provides a method for detecting doped elements in a rough-surface semiconductor material, comprising the following steps:

[0060] S1. Select the ion source;

[0061] S2. Place the sample in the sample chamber of the secondary ion mass spectrometer and evacuate it.

[0062] S3, First optical path adjustment;

[0063] S4. Secondary optical path adjustment;

[0064] S5. Set test conditions;

[0065] S6, Test Sample.

[0066] The ion source in S1 is a Cs source.

[0067] The Cs source is 133Cs+.

[0068] The sample was a textured silicon wafer with a roughness of 50 nm.

[0069] The textured silicon wafer is an acid-textured silicon wafer.

[0070] The method is used to detect the boron doping concentration of acid-textured silicon wafers.

[0071] The optical path adjustment in S3 includes the following steps:

[0072] (1) Adjust the beam intensity;

[0073] (2) Adjust the centers of the two beam spots to coincide;

[0074] (3) Eliminate dispersion or center the spot size within the dispersion;

[0075] (4) Adjust the preset value of the aperture of the transmission lens L4, and repeat (2) to keep the center of the beam spot unchanged;

[0076] (5) Adjust the preset value of the ion source pore size to maximize the beam intensity;

[0077] (6) Adjust the beam spot position to center the beam spot and turn on the grating.

[0078] The specific method of (1) in S3 is as follows: turn off the light source, adjust the beam intensity to 50nA by changing the transmission lens L2, then change the X and Y direction values ​​of the offset plate to adjust the beam intensity to 100nA; then alternately change the transmission lens L2 and the offset plate to adjust the beam intensity to 160nA.

[0079] The specific method in S3 (2) is as follows: adjust the beam intensity to 10nA by changing the transmission lens L2; ​​turn off the Raster and adjust the transmission lens L4 to focus the beam spot; increase and decrease the transmission lens L4 respectively to adjust two unfocused beam spots; make the centers of the two unfocused beam spots coincide by changing the X and Y direction values ​​of the aperture of the transmission lens L4.

[0080] The preset aperture values ​​of the transmission lens L4 in S3 (4) are 750, 300, 200, and 100, respectively.

[0081] The pore values ​​of the ion source in S3 (5) are set to 2000, 750, 400, 300, and 100, respectively.

[0082] The secondary optical path adjustment in S4 includes the following steps:

[0083] (1) Make the center of the image and the spot at the same point;

[0084] (2) In slit mode, change the paired electron microscope and adjust the electrostatic analyzer and mass number so that the center of the image remains unchanged when the paired electron microscope is changed;

[0085] (3) Adjust the exit slit;

[0086] (4) Adjust the entrance slit;

[0087] (5) Obtain the comparison gap value;

[0088] (6) Adjust the field gap value.

[0089] The specific method in S4 (1) is as follows: adjust the deflection plate and mass number so that when the image changes the transmission lens L1, the center of the image and the beam spot are at the same point.

[0090] The specific method of (3) in S4 is as follows: In slit mode, close the exit slit to 4000µm, adjust the transmission lens L1 to make the edge of the exit slit clear, and then open the exit slit to restore it to 400µm.

[0091] The specific method of S4 (4) is as follows: In slit mode, close the entrance slit to 60µm to make the edge of the entrance slit clear, and finally close the entrance slit again to make the edges of the exit slit and the entrance slit parallel; open the exit slit and the entrance slit.

[0092] The specific method in S4 (5) is as follows: Select a preset value of 150µm for the scanning range; set the transfer lens L1 and transfer lens L2 to 0; change the values ​​of the X and Y directions of the contrast slit transfer plate so that the beam position remains unchanged when the value of the transfer lens L1 is changed; after the contrast slit transfer plate is adjusted, set the transfer lens L1 to 0; change the values ​​of the X and Y directions of the contrast slit so that the beam position remains unchanged when the value of the transfer lens L2 is changed; remember the changed values ​​of the contrast slit transfer plate; read the unsaved preset value of the scanning range; input the recorded values ​​of the contrast slit transfer plate; select different preset values ​​of the contrast slit and repeat step 5 to obtain the correct contrast slit value and save it in the scanning menu.

[0093] The comparison gap value is 350.

[0094] The specific method in S4 (6) is as follows: turn off the grating, adjust the beam spot position to center the beam spot; select different preset values ​​of field gap (100~2000), and adjust the field gaps X and Y to center the field gap.

[0095] The preset values ​​for the field of view slits are 1800, 750, 400, and 100, respectively.

[0096] The test conditions in S5 are as follows: beam current intensity is 130 nA, scanning range is 150 µm, ion source aperture is 2000, transmission lens L4 aperture is 750, contrast slit is 400, field slit is 400, grating is 100, and electron gate is 80%.

[0097] Example 2

[0098] Example 2 provides a method for detecting doped elements in a rough-surface semiconductor material, comprising the following steps:

[0099] S1. Select the ion source;

[0100] S2. Place the sample in the sample chamber of the secondary ion mass spectrometer and evacuate it.

[0101] S3, First optical path adjustment;

[0102] S4. Secondary optical path adjustment;

[0103] S5. Set test conditions;

[0104] S6, Test Sample;

[0105] The ion source in S1 is an O source.

[0106] The Cs source is 16 O2 - .

[0107] The sample is a textured silicon wafer with a roughness of 50 nm.

[0108] The textured silicon wafer is an acid-textured silicon wafer.

[0109] The method is used to detect the phosphorus doping concentration of acid-textured silicon wafers.

[0110] The optical path adjustment in S3 includes the following steps:

[0111] (1) Adjust the beam intensity;

[0112] (2) Adjust the centers of the two beam spots to coincide;

[0113] (3) Eliminate dispersion or center the spot size within the dispersion;

[0114] (4) Adjust the preset value of the aperture of the transmission lens L4, and repeat (2) to keep the center of the beam spot unchanged;

[0115] (5) Adjust the preset value of the ion source pore size to maximize the beam intensity;

[0116] (6) Adjust the beam spot position to center the beam spot and turn on the grating.

[0117] The specific method of (1) in S3 is as follows: turn off the light source, adjust the beam intensity to 50nA by changing the transmission lens L2, then change the X and Y direction values ​​of the offset plate to adjust the beam intensity to 100nA; then alternately change the transmission lens L2 and the offset plate to adjust the beam intensity to 160nA.

[0118] The specific method in S3 (2) is as follows: adjust the beam intensity to 10nA by changing the transmission lens L2; ​​turn off the grating and adjust the distance from the transmission lens L4 to focus the beam spot; increase and decrease the transmission lens L4 respectively to adjust two unfocused beam spots; and make the centers of the two unfocused beam spots coincide by changing the X and Y direction values ​​of the aperture of the transmission lens L4.

[0119] The preset aperture values ​​of the transmission lens L4 in S3 (4) are 750, 300, 200, and 100, respectively.

[0120] The pore values ​​of the ion source in S3 (5) are set to 2000, 750, 400, 300, and 100, respectively.

[0121] The secondary optical path adjustment in S4 includes the following steps:

[0122] (1) Make the center of the image and the spot at the same point;

[0123] (2) In slit mode, change the paired electron microscope and adjust the electrostatic analyzer and mass number so that the center of the image remains unchanged when the paired electron microscope is changed;

[0124] (3) Adjust the exit slit;

[0125] (4) Adjust the entrance slit;

[0126] (5) Obtain the comparison gap value;

[0127] (6) Adjust the field gap value.

[0128] The specific method in S4 (1) is as follows: adjust the deflection plate and mass number so that when the image changes the transmission lens L1, the center of the image and the beam spot are at the same point.

[0129] The specific method in S4 (3) is as follows: in slit mode, close the exit slit to 4000µm to make the edge of the exit slit clear.

[0130] The specific method of S4 (4) is as follows: In slit mode, the entrance slit is closed to 30µm to make the edge of the entrance slit clear, and then the entrance slit is closed again to make the edges of the exit slit and the entrance slit parallel.

[0131] The specific method in S4 (5) is as follows: Select a preset value of 150µm for the scanning range; set the transfer lens L1 and transfer lens L2 to 0; change the values ​​of the X and Y directions of the contrast slit transfer plate so that the beam position remains unchanged when the value of the transfer lens L1 is changed; after the contrast slit transfer plate is adjusted, set the transfer lens L1 to 0; change the values ​​of the X and Y directions of the contrast slit so that the beam position remains unchanged when the value of the transfer lens L2 is changed; remember the changed values ​​of the contrast slit transfer plate; read the unsaved preset value of the scanning range; input the recorded values ​​of the contrast slit transfer plate; select different preset values ​​of the contrast slit and repeat step 5 to obtain the correct contrast slit value and save it in the scanning menu.

[0132] The comparison gap value is 350.

[0133] The specific method in S4 (6) is as follows: turn off the grating, adjust the beam spot position to center the beam spot; select different preset values ​​of field gap (100~2000), and adjust the field gaps X and Y to center the field gap.

[0134] The preset values ​​for the field of view slits are 1800, 750, 400, and 100, respectively.

[0135] The test conditions in S5 are as follows: beam current intensity is 130 nA, scanning range is 150 µm, ion source aperture is 2000, transmission lens L4 aperture is 750, contrast slit is 400, field slit is 400, grating is 100, and electron gate is 80%.

Claims

1. A method for detecting doped elements in a rough-surface semiconductor material, characterized in that, Includes the following steps: S1. Select the ion source; S2. Place the sample in the sample chamber of the secondary ion mass spectrometer and evacuate the vacuum. S3, First Optical Path Adjustment: The first optical path adjustment in S3 includes the following steps: (1) Adjust the beam intensity; (2) Adjust the centers of the two beam spots to coincide; (3) Eliminate dispersion or center the cluster spot within the dispersion; (4) Adjust the preset value of the aperture of the transmission lens L4, and repeat (2) to keep the center of the beam spot unchanged; (5) Adjust the preset value of the ion source pore size to maximize the beam intensity; (6) Adjust the beam spot position to center the beam spot and turn on the grating; S4. Secondary optical path adjustment: The secondary optical path adjustment in S4 includes the following steps: (1) Make the center of the image and the spot at the same point; (2) In slit mode, change the paired lens and adjust the electrostatic analyzer and mass number so that the center of the image remains unchanged when the paired electron microscope is changed. (3) Adjust the exit slit; (4) Adjust the entrance slit; (5) Obtain the comparison gap value; (6) Adjust the field gap value; S5. Set test conditions; S6, Test Sample.

2. The method for detecting doped elements in a rough-surface semiconductor material as described in claim 1, characterized in that, The ion source in S1 is either a Cs source or an O source.

3. The method for detecting doped elements in a rough-surface semiconductor material as described in claim 1, characterized in that, The sample in S2 is a textured silicon-based material.

4. A method for detecting doped elements in a rough-surface semiconductor material as described in claim 1, characterized in that, The specific method of (1) in S3 is as follows: turn off the light source, adjust the beam intensity to 40~50nA by changing the transmission lens L2, then change the X and Y direction values ​​of the offset plate to adjust the beam intensity to 90~100nA; then alternately change the transmission lens L2 and the offset plate to adjust the beam intensity to 150~170nA.

5. A method for detecting doped elements in a rough-surface semiconductor material as described in claim 1, characterized in that, In S3 (4), the preset aperture value of the transmission lens L4 is 100~750.

6. The method for detecting doped elements in a rough-surface semiconductor material as described in claim 1, characterized in that, The specific method of (3) in S4 is as follows: In slit mode, close the outgoing slit to 3000~5000µm, adjust the transmission lens L1 to make the edge clear, and then open the outgoing slit to restore it to 300~500µm.

7. The method for detecting doped elements in a rough-surface semiconductor material as described in claim 1, characterized in that, The test conditions in S5 are as follows: beam current intensity is 100~150nA, scanning range is 130~150µm, ion source aperture is 1500~3000, transmission lens L4 aperture is 300~800, contrast slit is 300~500, field slit is 300~500, grating is 70~120, and electron gate is 70~90%.

8. An application of the method for detecting doped elements in a rough-surface semiconductor material as described in any one of claims 1-7, characterized in that, It was applied to the detection of boron and phosphorus doping concentrations on silicon-based textured surfaces.

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