A detection method based on etching residues of silicon films with different doping types

Abstract

The present invention relates to a detection method for etching residues of film layers with different doping types based on silicon. The scanning morphology of an atomic force microscope is combined with a dC / dV Phase signal of a scanning capacitance microscope to determine whether there are etching residues on a delayered product and the form of the residues. The detection method of the atomic force microscope combined with the scanning capacitance microscope is more sensitive to the doping type on the surface of the delayered product, and can accurately determine whether there are etching residues on the delayered product. Even if the residues are thin or the area of ​​interest is small, the method has sufficient sensitivity for detection, and has the characteristics of high accuracy and good detection effect.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing technology, and in particular to a detection method based on etching residues of silicon films with different doping types. Background Art

[0002] Doping is the process of adding a certain amount of impurities into semiconductor materials. By introducing external atoms into semiconductor materials, their conductivity, optical properties and other characteristics can be changed, so that the semiconductor materials have specific functions or uses. Usually, the concentration of doping elements is at the ppm or even ppb level, so it is necessary to use a detection method with higher detection sensitivity such as secondary ion mass spectrometry for characterization. However, in silicon-based semiconductor products, there are often film layers of the same material with different doping types. Since the material is the same, but the doping type is different, it is difficult to accurately determine whether there is any residue after delamination from an elemental perspective.

[0003] When the residual film layer after delamination is thick and the area is large enough, secondary ion mass spectrometry can be used for in-depth analysis and judgment. For example, CN102610239A discloses a method for manufacturing a magnetic sensor, which includes forming a sensor stack with a multi-layer cap structure formed thereon. The multi-layer cap structure may include a first, a second, a third, and a fourth layer. The second layer is made of a material that is not easily oxidized and is different from the first layer. The sensor can be formed using a mask including a carbon hard mask. After the sensor stack is formed by ion etching, the hard mask can be removed by ion reactive etching. Then, a cleaning process is performed to remove the second, third, and fourth layers in the cap layer structure, wherein an endpoint detection method such as secondary ion mass spectrometry is used to detect the presence of the second layer. However, when the thickness of the remaining film after delamination is less than 10nm or the area of ​​interest is less than 50μm, or there is uneven residue after delamination, it is difficult to perform effective analysis using secondary ion mass spectrometry: when the residue is thin, the secondary ion mass spectrometry test has surface effects and the sputtering rate is relatively fast, the surface signal is usually affected and inaccurate, and when the signal is stable and the surface effect is excluded, the corresponding residue may have been etched, and therefore cannot be used to determine whether there is residue after delamination; when the size of the area of ​​interest is less than 50μm, it is smaller than the minimum size that can be tested by secondary ion mass spectrometry; when the residue after delamination is uneven, secondary ion mass spectrometry cannot accurately determine the residue situation.

[0004] CN 103337465A discloses a method for detecting etching residues, which relates to the field of display technology and can achieve the purpose of detecting etching residues, thereby improving product yield; the method comprises obtaining a pattern at a location to be detected; performing an infrared spectrum test on the pattern at the location to be detected to obtain an infrared spectrum graph; and judging whether there is residual material according to the infrared spectrum graph. The method is used for detecting etching residues during the preparation of array substrates or assembling box substrates. However, the method still has certain limitations when the residual film layer after delamination is thin, the area is small, or the residual film layer is uneven.

[0005] Therefore, in view of the shortcomings of the existing technology, it is urgently necessary to provide a detection method that can accurately determine whether there are etching residues in silicon film layers of different doping types. Summary of the invention

[0006] The purpose of the present invention is to provide a detection method for etching residues of film layers with different doping types of silicon, which uses the scanning morphology of an atomic force microscope combined with the dC / dV Phase signal of a scanning capacitance microscope to determine whether there are etching residues in a delayered product, and has the characteristics of high accuracy and good effect.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for detecting etching residues of films with different doping types based on silicon, and the detection method comprises the following steps:

[0009] (1) fixing the sample to be delaminated on the sample stage of a scanning capacitance microscope, analyzing the surface of the sample to be delaminated using the scanning capacitance microscope and recording dC / dV Phase signals;

[0010] (2) performing a de-layering treatment on the sample to be de-layered in step (1) to obtain a de-layered sample;

[0011] (3) Fixing the delayered sample in step (2) on the sample stage of a scanning capacitance microscope, scanning the area of ​​interest of the delayered sample using an atomic force microscope to determine the morphology uniformity of the area of ​​interest; based on the morphology uniformity result of the area of ​​interest, analyzing the area of ​​interest using a scanning capacitance microscope and recording a dC / dVPhase signal, and obtaining the etching residue in the area of ​​interest of the delayered sample according to the dC / dV Phase signal.

[0012] The present invention provides a detection method for etching residues based on silicon films of different doping types, which uses the scanning morphology of an atomic force microscope combined with the dC / dV Phase signal of a scanning capacitance microscope to determine whether there are etching residues on a delayered product and the form of the residues. The detection method of the atomic force microscope combined with the scanning capacitance microscope is more sensitive to the doping type on the surface of the delayered product, and can accurately determine whether there are etching residues on the delayered product. Even if the residues are thin or the area of ​​interest is small, it has sufficient sensitivity for detection, and has the characteristics of high accuracy and good detection effect.

[0013] Preferably, the fixing method in step (1) includes fixing with conductive silver paste.

[0014] Preferably, the fixing in step (1) is to ensure good electrical contact between the sample to be delaminated and the sample stage.

[0015] Preferably, in the analysis of step (1), the AC voltage range of the scanning capacitance microscope is set to 0.1-4V, for example, it can be 0.1V, 1V, 2V, 3V or 4V, but is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable.

[0016] Preferably, in the analysis of step (1), the scanning speed of the scanning capacitance microscope is set to 0.1-1 Hz, for example, it can be 0.1 Hz, 0.3 Hz, 0.5 Hz, 0.8 Hz or 1 Hz, but it is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0017] Preferably, in the analysis of step (1), the probe of the scanning capacitance microscope is set in contact mode with the sample to be delaminated.

[0018] Preferably, in the analysis of step (1), the scanning range of the scanning capacitance microscope is set to 0.1μm*0.1μm-80μm*80μm, for example, it can be 0.1μm*0.1μm, 1μm*1μm, 10μm*10μm, 38μm*38μm, 45μm*45μm, 48μm*48μm or 80μm*80μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0019] Preferably, the fixing method in step (3) includes fixing with conductive silver paste.

[0020] The fixing method in the present invention is not limited to the conductive silver paste, and any conductive method that can ensure good conductivity can be used in the present invention.

[0021] Preferably, the fixing in step (3) is to ensure good electrical contact between the delaminated sample and the sample stage.

[0022] Preferably, the size of the region of interest in step (3) is less than 50 μm, for example, it can be 48 μm, 45 μm, 42 μm, 40 μm or 38 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0023] In the present invention, since the maximum scanning range of the atomic force microscope and the scanning capacitance microscope is 80*80 μm at one time, it is particularly effective for etching residue analysis of patterned wafers or device levels with a focus area of ​​less than 50 μm.

[0024] Preferably, the morphology uniformity of the region of interest in step (3) includes uniform morphology and non-uniform morphology.

[0025] Preferably, the morphology of the area of ​​interest is uniform, and the same parameters as those of the scanning capacitance microscope in step (1) are used to analyze the area of ​​interest and record the dC / dV Phase signal; the dC / dV Phase signal is the same as the dC / dV Phase signal obtained in step (1), indicating that there are etching residues in the area of ​​interest of the delayered sample; the dC / dV Phase signal is opposite to the dC / dV Phase signal obtained in step (1), indicating that there are no etching residues in the area of ​​interest of the delayered sample.

[0026] Preferably, the morphology of the area of ​​interest is uneven, and a scanning capacitance microscope is used to analyze the area of ​​interest and record a dC / dV Phase signal; the dC / dV Phase signal has positive and negative conditions, indicating that there are etching residues in the area of ​​interest of the delayered sample; the dC / dV Phase signal is the same as the dC / dV Phase signal obtained in step (1), indicating that there are etching residues in the area of ​​interest of the delayered sample; the dC / dV Phase signal is opposite to the dC / dV Phase signal obtained in step (1), indicating that there are no etching residues in the area of ​​interest of the delayered sample.

[0027] As a preferred technical solution of the detection method described in the present invention, the detection method comprises the following steps:

[0028] (1) The sample to be removed is fixed on the sample stage of a scanning capacitance microscope using a conductive silver paste so that the sample to be removed is in good electrical contact with the sample stage, and then the surface of the sample to be removed is analyzed using a scanning capacitance microscope and a dC / dV Phase signal is recorded; in the analysis, the AC voltage range of the scanning capacitance microscope is set to 0.1-4V, the scanning speed is set to 0.1-1Hz, the probe and the sample to be removed are in contact mode, and the scanning range is 0.1μm*0.1μm-80μm*80μm;

[0029] (2) performing a de-layering treatment on the sample to be de-layered in step (1) to obtain a de-layered sample;

[0030] (3) The delayered sample of step (2) is fixed on the sample stage of a scanning capacitance microscope by using a conductive silver paste to ensure good electrical contact between the delayered sample and the sample stage, and then an atomic force microscope is used to scan a region of interest of the delayered sample, wherein the size of the region of interest is less than 50 μm, and the morphology uniformity of the region of interest is determined, wherein the morphology uniformity of the region of interest includes morphology uniformity and morphology non-uniformity; based on the morphology uniformity result of the region of interest, the region of interest is analyzed by using a scanning capacitance microscope and a dC / dV Phase signal is recorded, and the etching residue of the region of interest of the delayered sample is obtained according to the dC / dV Phase signal;

[0031] The morphology of the area of ​​interest is uniform, and the same parameters as those of the scanning capacitance microscope in step (1) are used to analyze the area of ​​interest and record the dC / dV Phase signal; the dC / dV Phase signal is the same as the dC / dVPhase signal obtained in step (1), indicating that there are etching residues in the area of ​​interest of the delayered sample; the dC / dV Phase signal is opposite to the dC / dV Phase signal obtained in step (1), indicating that there are no etching residues in the area of ​​interest of the delayered sample;

[0032] The morphology of the area of ​​interest is uneven, and a scanning capacitance microscope is used to analyze the area of ​​interest and record a dC / dV Phase signal; the dC / dV Phase signal has two conditions, positive and negative, indicating that there are etching residues in the area of ​​interest of the delayered sample; the dC / dV Phase signal is the same as the dC / dV Phase signal obtained in step (1), indicating that there are etching residues in the area of ​​interest of the delayered sample; the dC / dV Phase signal is opposite to the dC / dV Phase signal obtained in step (1), indicating that there are no etching residues in the area of ​​interest of the delayered sample.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The present invention provides a detection method for etching residues based on silicon films of different doping types, which uses the scanning morphology of an atomic force microscope combined with the dC / dV Phase signal of a scanning capacitance microscope to determine whether there are etching residues on a delayered product and the form of the residues. The detection method of the atomic force microscope combined with the scanning capacitance microscope is more sensitive to the doping type on the surface of the delayered product, and can accurately determine whether there are etching residues on the delayered product. Even if the residues are thin or the area of ​​interest is small, it has sufficient sensitivity for detection, and has the characteristics of high accuracy and good detection effect. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0036] Example 1

[0037] This embodiment provides a method for detecting etching residues of films with different doping types based on silicon, and the detection method comprises the following steps:

[0038] (1) The sample to be removed is fixed on the sample stage of a scanning capacitance microscope using a conductive silver paste so that the sample to be removed is in good electrical contact with the sample stage, and then the surface of the sample to be removed is analyzed using a scanning capacitance microscope and a dC / dV Phase signal is recorded; in the analysis, the AC voltage of the scanning capacitance microscope is set to 1V, the scanning speed is set to 0.5Hz, the probe and the sample to be removed are in contact mode, and the scanning range is 45μm*45μm;

[0039] (2) performing a de-layering treatment on the sample to be de-layered in step (1) to obtain a de-layered sample;

[0040] (3) The delayered sample in step (2) is fixed on the sample stage of a scanning capacitance microscope using conductive silver paste to ensure good electrical contact between the delayered sample and the sample stage, and then an atomic force microscope is used to scan a region of interest of the delayered sample, wherein the size of the region of interest is 45 μm. In this embodiment, the morphology of the region of interest is uniform, and then the region of interest is analyzed using the same parameters as the scanning capacitance microscope in step (1) and a dC / dV Phase signal is recorded; the dC / dV Phase signal in this embodiment is the same as the dC / dV Phase signal obtained in step (1), indicating that etching residues exist in the region of interest of the delayered sample.

[0041] Example 2

[0042] This embodiment provides a method for detecting etching residues of films with different doping types based on silicon, and the detection method comprises the following steps:

[0043] (1) The sample to be removed is fixed on the sample stage of a scanning capacitance microscope using a conductive silver paste so that the sample to be removed is in good electrical contact with the sample stage, and then the surface of the sample to be removed is analyzed using a scanning capacitance microscope and a dC / dV Phase signal is recorded; in the analysis, the AC voltage of the scanning capacitance microscope is set to 1V, the scanning speed is set to 0.5Hz, the probe and the sample to be removed are in contact mode, and the scanning range is 48μm*48μm;

[0044] (2) performing a de-layering treatment on the sample to be de-layered in step (1) to obtain a de-layered sample;

[0045] (3) The delayered sample in step (2) is fixed on the sample stage of a scanning capacitance microscope using conductive silver paste to ensure good electrical contact between the delayered sample and the sample stage, and then an atomic force microscope is used to scan a region of interest of the delayered sample, wherein the size of the region of interest is 48 μm. In this embodiment, the morphology of the region of interest is uniform, and then the region of interest is analyzed using the same parameters as the scanning capacitance microscope in step (1) and a dC / dV Phase signal is recorded; the dC / dV Phase signal in this embodiment is opposite to the dC / dV Phase signal obtained in step (1), indicating that there is no etching residue in the region of interest of the delayered sample.

[0046] Example 3

[0047] This embodiment provides a method for detecting etching residues of films with different doping types based on silicon, and the detection method comprises the following steps:

[0048] (1) The sample to be removed is fixed on the sample stage of a scanning capacitance microscope using a conductive silver paste so that the sample to be removed is in good electrical contact with the sample stage, and then the surface of the sample to be removed is analyzed using a scanning capacitance microscope and a dC / dV Phase signal is recorded; in the analysis, the AC voltage of the scanning capacitance microscope is set to 1V, the scanning speed is set to 0.5Hz, the probe and the sample to be removed are in contact mode, and the scanning range is 38μm*38μm;

[0049] (2) performing a de-layering treatment on the sample to be de-layered in step (1) to obtain a de-layered sample;

[0050] (3) The delayered sample in step (2) is fixed on the sample stage of a scanning capacitance microscope using conductive silver paste to ensure good electrical contact between the delayered sample and the sample stage. Then, an atomic force microscope is used to scan a region of interest of the delayered sample. The size of the region of interest is 38 μm. In this embodiment, the morphology of the region of interest is uneven. Then, a scanning capacitance microscope is used to analyze the region of interest and record dC / dV Phase signals. In this embodiment, the dC / dV Phase signals exist in both positive and negative situations, indicating that etching residues exist in the region of interest of the delayered sample.

[0051] Example 4

[0052] This embodiment provides a method for detecting etching residues of films with different doping types based on silicon, and the detection method comprises the following steps:

[0053] (1) The sample to be removed is fixed on the sample stage of a scanning capacitance microscope using a conductive silver paste so that the sample to be removed is in good electrical contact with the sample stage, and then the surface of the sample to be removed is analyzed using a scanning capacitance microscope and a dC / dV Phase signal is recorded; in the analysis, the AC voltage of the scanning capacitance microscope is set to 1V, the scanning speed is set to 0.5Hz, the probe and the sample to be removed are in contact mode, and the scanning range is 38μm*38μm;

[0054] (2) performing a de-layering treatment on the sample to be de-layered in step (1) to obtain a de-layered sample;

[0055] (3) The delayered sample in step (2) is fixed on the sample stage of a scanning capacitance microscope using conductive silver paste to ensure good electrical contact between the delayered sample and the sample stage. Then, an atomic force microscope is used to scan a region of interest of the delayered sample. The size of the region of interest is 38 μm. In this embodiment, the morphology of the region of interest is uneven. Then, a scanning capacitance microscope is used to analyze the region of interest and record a dC / dV Phase signal. The dC / dV Phase signal in this embodiment is the same as the dC / dV Phase signal obtained in step (1), indicating that etching residues exist in the region of interest of the delayered sample.

[0056] Example 5

[0057] This embodiment provides a method for detecting etching residues of films with different doping types based on silicon, and the detection method comprises the following steps:

[0058] (1) The sample to be removed is fixed on the sample stage of a scanning capacitance microscope using a conductive silver paste so that the sample to be removed is in good electrical contact with the sample stage, and then the surface of the sample to be removed is analyzed using a scanning capacitance microscope and a dC / dV Phase signal is recorded; in the analysis, the AC voltage of the scanning capacitance microscope is set to 1V, the scanning speed is set to 0.5Hz, the probe and the sample to be removed are in contact mode, and the scanning range is 38μm*38μm;

[0059] (2) performing a de-layering treatment on the sample to be de-layered in step (1) to obtain a de-layered sample;

[0060] (3) The delayered sample in step (2) is fixed on the sample stage of a scanning capacitance microscope using a conductive silver paste to ensure good electrical contact between the delayered sample and the sample stage. Then, an atomic force microscope is used to scan a region of interest of the delayered sample. The size of the region of interest is 38 μm. In this embodiment, the morphology of the region of interest is uneven. Then, a scanning capacitance microscope is used to analyze the region of interest and record a dC / dV Phase signal. The dC / dV Phase signal in this embodiment is opposite to the dC / dV Phase signal obtained in step (1), indicating that there is no etching residue in the region of interest of the delayered sample.

[0061] Comparative Example 1

[0062] This comparative example provides a method for detecting etching residues of film layers with different doping types based on silicon. The size of the area of ​​interest of the de-layered sample is 38 μm, and secondary ion mass spectrometry is used for etching residue analysis.

[0063] In this comparative example, since the etching residue analysis is performed using secondary ion mass spectrometry, the size of the area of ​​interest is relatively small, and it is impossible to accurately determine whether there is etching residue in the area of ​​interest.

[0064] To summarize, the present invention provides a detection method for etching residues based on silicon films of different doping types, which uses the scanning morphology of an atomic force microscope combined with the dC / dV Phase signal of a scanning capacitance microscope to determine whether there are etching residues on the delayered product and the form of the residues. The detection method of an atomic force microscope combined with a scanning capacitance microscope is more sensitive to the doping type on the surface of the delayered product, and can accurately determine whether there are etching residues on the delayered product. Even if the residues are thin or the area of ​​concern is small, it has sufficient sensitivity for detection, and has the characteristics of high accuracy and good detection effect.

[0065] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A method for detecting etching residues of silicon films with different doping types, characterized in that: The detection method comprises the following steps: (1) Fixing the sample to be delaminated on the sample stage of a scanning capacitance microscope, analyzing the surface of the sample to be delaminated using the scanning capacitance microscope and recording dC / dV Phase signals; (2) performing a de-layering treatment on the sample to be de-layered in step (1) to obtain a de-layered sample; (3) fixing the delayered sample in step (2) on the sample stage of a scanning capacitance microscope, and scanning the region of interest of the delayered sample using an atomic force microscope to determine the morphological uniformity of the region of interest; Based on the morphology uniformity result of the concerned area, the concerned area is analyzed by using a scanning capacitance microscope and a dC / dV Phase signal is recorded, and the etching residue in the concerned area of ​​the delayered sample is obtained according to the dC / dV Phase signal.

2. The detection method according to claim 1, characterized in that: The fixing method in step (1) includes fixing with conductive silver paste.

3. The detection method according to claim 1, characterized in that: The fixing in step (1) is to ensure good electrical contact between the sample to be delaminated and the sample stage.

4. The detection method according to claim 1, characterized in that: In the analysis of step (1), the AC voltage range of the scanning capacitance microscope is set to 0.1-4V.

5. The detection method according to claim 1, characterized in that: In the analysis of step (1), the scanning speed of the scanning capacitance microscope is set to 0.1-1 Hz.

6. The detection method according to claim 1, characterized in that: In the analysis of step (1), the probe of the scanning capacitance microscope is set to a contact mode with the sample to be delaminated.

7. The detection method according to claim 1, characterized in that: In the analysis of step (1), the scanning range of the scanning capacitance microscope is set to 0.1 μm*0.1 μm-80 μm*80 μm.

8. The detection method according to claim 1, characterized in that: The fixing method in step (3) includes fixing with conductive silver paste.

9. The detection method according to claim 1, characterized in that: The fixation in step (3) is to ensure good electrical contact between the delaminated sample and the sample stage.

10. The detection method according to claim 1, characterized in that: The size of the region of interest in step (3) is less than 50 μm.

11. The detection method according to claim 1, characterized in that: The morphology uniformity of the region of interest in step (3) includes uniform morphology and non-uniform morphology.

12. The detection method according to claim 11, characterized in that The morphology of the area of ​​interest is uniform, and the same parameters as those of the scanning capacitance microscope in step (1) are used to analyze the area of ​​interest and record the dC / dV Phase signal; the dC / dV Phase signal is the same as the dC / dV Phase signal obtained in step (1), indicating that there are etching residues in the area of ​​interest of the delayered sample; the dC / dV Phase signal is opposite to the dC / dV Phase signal obtained in step (1), indicating that there are no etching residues in the area of ​​interest of the delayered sample.

13. The detection method according to claim 11, characterized in that The morphology of the area of ​​interest is uneven, and a scanning capacitance microscope is used to analyze the area of ​​interest and record a dC / dV Phase signal; the dC / dV Phase signal has two conditions, positive and negative, indicating that there are etching residues in the area of ​​interest of the delayered sample; the dC / dV Phase signal is the same as the dC / dV Phase signal obtained in step (1), indicating that there are etching residues in the area of ​​interest of the delayered sample; the dC / dV Phase signal is opposite to the dC / dV Phase signal obtained in step (1), indicating that there are no etching residues in the area of ​​interest of the delayered sample.