System and method for detecting slippage defect in epitaxial layer
Through detection light scanning and scattered light signal analysis, combined with the crystal orientation simulation of the epitaxial layer, efficient detection of slip defects in the epitaxial layer of semiconductor devices is achieved, which solves the problems of high detection difficulty and low efficiency in the existing technology, and improves product quality. yield rate.
Patent Information
- Application Number
- CN202311566291.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-22
- Publication Date
- 2025-01-24
AI Technical Summary
In the manufacturing process of semiconductor integrated circuits, slip defects in the epitaxial layer can easily lead to device failure, and it is difficult for the prior art to detect these defects efficiently.
By using detection light to scan the epitaxial layer on the wafer, scattered light signals are collected, linear defects are screened out based on the intensity distribution of the scattered light, and a slip defect model is simulated based on the crystal orientation of the epitaxial layer, and comparison is performed to determine slip defects.
It achieves convenient and efficient slip defect detection, can obtain detection results quickly and accurately, and improves the product yield of semiconductor devices.
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Figure CN119361448A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor technology, and in particular to a detection system and a detection method for slip defects in an epitaxial layer. Background Art
[0002] In the manufacture of semiconductor integrated circuits, the required epitaxial layer is often grown on a wafer using an epitaxial process. During the epitaxial growth process, the epitaxial material will grow along the crystal axis of the wafer. However, during the epitaxial growth process, the epitaxial layer may be affected by the substrate or the process, resulting in epitaxial defects in the grown epitaxial layer, such as scratch defects on the surface of the epitaxial layer and stacking fault defects and slip dislocations inside the epitaxial layer. Fabricating a semiconductor device on an epitaxial layer with defects is likely to affect the performance of the device.
[0003] Among them, the slip defect in the epitaxial layer has a particularly prominent impact on the device. When there is a slip defect in the area where the device is located, it will most likely directly cause the device to fail. Therefore, it is necessary to detect the slip defect of the epitaxial layer to improve the yield of the product. Summary of the invention
[0004] The object of the present invention is to provide a method for detecting slip defects in an epitaxial layer, so as to achieve convenient and efficient slip defect detection.
[0005] In this regard, the present invention provides a method for detecting slip defects in an epitaxial layer, comprising: scanning the epitaxial layer on a wafer with detection light, and collecting scattered light signals from the epitaxial layer; screening out scattered light signals with linear distribution according to the intensity distribution of the scattered light to obtain linear defects on the epitaxial layer; and simulating a corresponding slip defect model according to the crystal orientation of the epitaxial layer, and comparing each linear defect with the slip defect model, wherein a linear defect that matches the slip defect model is determined to be a slip defect.
[0006] Optionally, before scanning the epitaxial layer, the epitaxial layer is divided into a plurality of detection areas; the detection light scans each detection area of the epitaxial layer to respectively collect scattered light from each detection area.
[0007] Optionally, the method of dividing the epitaxial layer into multiple detection areas includes: establishing polar coordinates with the center of the epitaxial layer as the pole, dividing the epitaxial layer into at least two sectors at a predetermined angle, and further dividing each sector into at least two areas with a predetermined size along the radial direction of the epitaxial layer.
[0008] Optionally, after collecting the scattered light from the epitaxial layer, the method further includes: setting a corresponding signal-to-noise ratio threshold for each detection area, and enabling each detection area to filter noise signals based on the corresponding signal-to-noise ratio threshold.
[0009] Optionally, after obtaining the slip defects, the method further includes: locating the position of each slip defect in the epitaxial layer and obtaining a distribution map of each slip defect.
[0010] Optionally, the slip line in the slip defect model extends along a predetermined angle and a predetermined direction, wherein the linear defect matching the slip defect model is a linear defect extending along the predetermined angle and a predetermined direction matching the slip defect model.
[0011] The present invention also provides a detection system for slip defects of an epitaxial layer, comprising: a detection light emitting module, used to emit detection light to scan the epitaxial layer on a wafer; a scattered light collection module, used to collect scattered light signals from the epitaxial layer; a first screening module, used to screen out scattered light signals with linear distribution according to the intensity distribution of the scattered light, so as to obtain linear defects on the epitaxial layer; and a second screening module, used to compare each linear defect with a slip defect model, and screen out linear defects that match the slip defect model to determine them as slip defects, wherein the slip defect model is simulated according to the crystal orientation of the epitaxial layer.
[0012] Optionally, the detection system further includes: a division module, used for dividing the epitaxial layer into a plurality of detection areas.
[0013] Optionally, the division module is used to establish polar coordinates for the epitaxial layer with its center as the pole, divide the epitaxial layer into at least two sectors at a predetermined angle, and further divide each sector into at least two regions with a predetermined size along the radial direction of the epitaxial layer.
[0014] Optionally, the detection system further includes: a noise filtering module, which is used to set a corresponding signal-to-noise ratio threshold for each detection area, and enable each detection area to filter noise signals based on the corresponding signal-to-noise ratio threshold.
[0015] Optionally, the detection system further includes: an information integration module, which is used to locate the position of each slip defect in the epitaxial layer and obtain a distribution map of each slip defect.
[0016] The present invention also provides a semiconductor processing method, comprising: forming an epitaxial layer on a wafer, wherein a plurality of device areas for preparing semiconductor devices are defined on the epitaxial layer; detecting slip defects in the epitaxial layer using the slip defect detection method as described above; and determining whether the slip defects fall into more than a predetermined number of device areas; if so, reworking or scrapping the current epitaxial layer; if not, continuing the processing of semiconductor devices on the epitaxial layer.
[0017] In the method for detecting slip defects in the epitaxial layer provided by the present invention, a corresponding slip defect model is simulated according to the crystal orientation characteristics of the epitaxial layer as a reference object for the slip defect, so that after the linear defects are screened out, the part matching the slip defect model can be further screened out from the linear defects, thereby detecting the slip defects in the epitaxial layer. The detection method provided by the present invention can obtain the detection results of the slip defects more quickly and accurately, and can monitor the process stability of the semiconductor equipment based on the detection results.
[0018] In addition, after detecting the slip defect in the epitaxial layer, the detection result can also be used to predict the impact on the semiconductor device formed later, so that the current epitaxial layer can be processed accordingly in time to avoid the slip defect causing significant damage to the semiconductor device formed later. Specifically, the number of impacts on the semiconductor device formed later can be predicted based on the distribution of the slip defect. When the slip defect falls into the device area of more than a predetermined number, the current epitaxial layer can be reworked or scrapped in time, avoiding the problem of failure of the semiconductor device formed later due to the slip defect in advance, and improving the yield of the product. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 Schematic diagram of a flow chart of a method for detecting slip defects in an epitaxial layer according to an embodiment of the present invention.
[0020] Figure 2 It is a schematic diagram of dividing the epitaxial layer into regions according to an embodiment of the present invention.
[0021] Figure 3 Another schematic diagram of dividing the epitaxial layer into regions.
[0022] Figure 4 A schematic diagram of a slip defect occurring in an epitaxial layer.
[0023] Figure 5 Schematic diagram of the structure of a system for detecting slip defects of an epitaxial layer in one embodiment of the present invention. DETAILED DESCRIPTION
[0024] The core idea of the present invention is to provide a method for detecting slip defects in an epitaxial layer, which can realize efficient and convenient slip detection. The detection method specifically includes: using detection light to scan the epitaxial layer on the wafer and collecting scattered light signals from the epitaxial layer; screening out scattered light signals with linear distribution according to the intensity distribution of scattered light to obtain linear defects on the epitaxial layer; simulating a corresponding slip defect model according to the crystal orientation of the epitaxial layer, and comparing each linear defect with the slip defect model, wherein the linear defect that matches the slip defect model is determined to be a slip defect.
[0025] It should be noted that when there is a slip defect in the epitaxial layer, the slip line of the slip defect generally extends along a specific crystal direction based on the crystal structure characteristics of the epitaxial layer. Therefore, for the same epitaxial layer, when there are multiple slip defects therein, the multiple slip lines basically extend along the same angle and the same direction. Based on this, the present invention simulates the corresponding slip line according to the crystal characteristics of the epitaxial layer as a slip defect model. When the linear defect is consistent with the slip defect model, it can be determined that the linear defect is a slip defect.
[0026] In a specific example, before the epitaxial layer is scanned with the detection light, the epitaxial layer can be divided into a plurality of detection areas, so that the detection light can be used to scan each detection area of the epitaxial layer to collect scattered light from each detection area. In this example, by dividing the epitaxial layer with a larger area into a plurality of smaller detection areas, each small area can be detected separately, which is conducive to improving the defect detection rate and reducing the risk of missed detection.
[0027] Furthermore, before selecting the scattered light signal with linear distribution according to the intensity distribution of the scattered light, it can also include: performing noise filtering on the scattered light signal collected from the epitaxial layer to reduce the interference of the noise signal, so that a more accurate scattered light map can be obtained based on the filtered scattered light signal. Specifically, a corresponding signal-to-noise ratio threshold S / N (for example, S / N=3:1) can be set for each detection area, and each detection area can filter the noise signal based on the corresponding signal-to-noise ratio threshold.
[0028] In addition, after detecting the slip defects in the epitaxial layer, the positions of each slip defect in the epitaxial layer can be further located to obtain the distribution of slip defects on the epitaxial layer, so that the detection results of slip defects can be obtained more intuitively and clearly, which is conducive to defect analysis and provides guidance for subsequent process improvements.
[0029] The following is a further detailed description of the slip defect detection system and detection method in the epitaxial layer proposed by the present invention in combination with specific embodiments. The advantages and features of the present invention will become clearer according to the following description. It should be noted that the drawings are all in a very simplified form and are not in precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.
[0030] Figure 1 FIG. 1 is a flow chart of a method for detecting slip defects in an epitaxial layer according to an embodiment of the present invention. Figure 1 As shown, the slip defect detection method provided in this embodiment includes the following steps.
[0031] Step S110, providing a wafer with an epitaxial layer formed thereon, and dividing the epitaxial layer into a plurality of detection regions, so that in the subsequent detection process, the scattered light signals in each detection region can be analyzed separately, thereby improving the defect detection rate and reducing the risk of missed detection.
[0032] In a specific example, the method for dividing the epitaxial layer is, for example, to establish polar coordinates with the center of the epitaxial layer as the pole, and to divide the epitaxial layer into at least two sectors at a predetermined angle θ, and to further divide each sector into at least two regions at a predetermined size D along the radial direction of the epitaxial layer. The example diagram of dividing the epitaxial layer into multiple detection regions can be referred to Figure 2 It should be noted that, compared with dividing at least two annular detection areas (for example Figure 3 Compared with the example shown in the figure, the way of dividing the detection area in this example can make each detection area more concentrated, and the area of the detection area is smaller, which can greatly improve the defect detection rate.
[0033] For example Figure 3 In the example shown, when the same detection zone (with Figure 3 If there are more defects in the detection area S12 shown in the figure, the scattered light intensity collected in the area is also higher. At the same time, the scattered light intensity corresponding to different defects is also different, which may easily lead to small defects being ignored (for example Figure 3 The defect indicated by the arrow in the figure may be ignored, resulting in missed inspection. Figure 2 In the example shown, the various inspection areas are concentrated and their areas are reduced, which helps to alleviate the problem of missing inspections due to a large number of defects in the same inspection area.
[0034] Step S120, use the detection light to scan the epitaxial layer on the wafer and collect scattered light signals from the epitaxial layer. In this embodiment, the epitaxial layer is divided into a plurality of detection areas, and the scattered light signals in each detection area can be obtained.
[0035] Among them, the scattering properties of the detection light for the defective position and the defect-free position in the epitaxial layer are different, so that the scattered light intensities obtained for the defective position and the defect-free position are different. Generally, the scattered light intensity at the defective position is greater. In a specific example, the epitaxial layer can be scanned in a spiral scanning manner to obtain scanning information for the surface of the epitaxial layer and the inside of the epitaxial layer. In addition, the collected scattered light signal contains most of the defect information on the epitaxial layer, such as particulate matter, surface scratches, stacking fault defects, slip defects, etc. on the epitaxial layer.
[0036] Step S130 , filtering the collected scattered light signal from the epitaxial layer to reduce the interference of the noise signal, so that a more accurate scattered light map can be obtained based on the filtered scattered light signal.
[0037] In this embodiment, the epitaxial layer is divided into multiple detection areas, so noise filtering can be performed for each detection area. In a further solution, a corresponding signal-to-noise ratio threshold S / N (for example, S / N=3:1) can be set for each detection area, and each detection area can filter the noise signal based on the corresponding signal-to-noise ratio threshold S / N. It should be noted that for Figure 3 As for the division method shown, the detection area is larger. When there are more defects in the same detection area, it is easy to collect scattered light signals with higher intensity. At this time, when noise filtering is performed based on the signal-to-noise ratio threshold S / N, it is very easy to filter the signal representing the defect, resulting in the failure to detect some defect signals, causing the problem of defect leakage. Figure 2 The division method shown can effectively improve the problem that a large number of defects appear in the same detection area, causing the optical signals of small defects therein to be easily filtered out.
[0038] Afterwards, the filtered scattered light signals in each detection area may be analyzed to screen out the scattered light signals with linear distribution, with reference to step S140 for details.
[0039] Step S140 , screening out scattered light signals with linear distribution according to the intensity distribution of scattered light in each detection area, wherein the scattered light signals with linear distribution can reflect linear defects on the epitaxial layer.
[0040] In a specific example, whether there are defects in each detection area can be determined based on the intensity of the scattered light. When the intensity of the scattered light is high, it means that there is a defect. Then, a light map is drawn for the scattered light that characterizes the defect. At this time, if there is a point defect in the epitaxial layer, a point-like strong light pattern will be obtained. If there is a linear defect in the epitaxial layer, a linear strong light pattern will be obtained. After that, the linear strong light pattern can be screened out from the scattered light map to obtain the linear defect.
[0041] That is to say, in the scattered light image corresponding to the scattered light signal, the scattered light with higher intensity can show the defect pattern. For example, the scattered light signal corresponding to the particles on the epitaxial layer can show a point-like strong light pattern; and the intensity distribution of the scattered light corresponding to the scratches and slip defects on the epitaxial layer can be displayed as a linear strong light pattern. By screening out the linear strong light pattern, the corresponding linear defects can be obtained. At this time, the screened linear defects include slip defects, and may also include other linear defects such as scratches on the surface of the epitaxial layer.
[0042] Step S150, each linear defect is compared with a slip defect model, and a linear defect that matches the slip defect model can be determined as a slip defect. The slip defect model is specifically simulated according to the crystal orientation of the epitaxial layer, which can reflect the extension angle and extension direction of the slip line when a slip defect occurs in the current epitaxial layer.
[0043] For example Figure 4 A schematic diagram of a slip defect in an epitaxial layer is shown in FIG. Figure 4 As shown in the figure, there are multiple linear defects matching the slip lines of the slip defect model in the same epitaxial layer, and the linear defects can be judged as slip defects, and the extension angles and extension directions of the slip lines of the slip defects appearing in the same epitaxial layer are basically consistent. On this basis, the size of each slip defect (i.e., the extension length of the slip line of each slip defect) can be further obtained.
[0044] Step S160, locate the position of each slip defect in the epitaxial layer to obtain a distribution map of each slip defect. In this way, the distribution of each slip defect in the epitaxial layer can be more intuitively known, which is convenient for further analysis of the defects.
[0045] This embodiment also provides a system for detecting slip defects of an epitaxial layer, which is used to perform the slip defect detection process as described above.
[0046] Figure 5 A schematic diagram of the structure of a detection system for slip defects of an epitaxial layer is shown in FIG. Figure 5 As shown, the detection system includes: a detection light emitting module, a scattered light collection module, a first screening module, and a second screening module.
[0047] Specifically, the detection light emission module is used to emit detection light to scan the epitaxial layer on the wafer, and the scattered light collection module collects the scattered light signal from the epitaxial layer. The detection light has different scattering properties for defective positions and non-defective positions in the epitaxial layer, so that the scattered light intensities obtained for defective positions and non-defective positions are different. Generally, the scattered light intensity at the defective position is greater. In addition, the collected scattered light signal contains most of the defect information on the epitaxial layer, such as particulate matter, surface scratches, stacking fault defects, slip defects, etc. on the epitaxial layer.
[0048] And, the first screening module receives the scattered light signal, and screens out the scattered light signal with linear distribution according to the intensity distribution of the scattered light, so as to obtain the linear defects on the epitaxial layer. Specifically, the corresponding scattered light graph can be obtained according to the scattered light signal, in which the scattered light with higher intensity can show the defect pattern. For example, the scattered light signal corresponding to the particulate matter on the epitaxial layer is a point-like strong light pattern; and the intensity distribution of the scattered light corresponding to the scratches and slip defects on the epitaxial layer can be displayed as a linear strong light pattern. In this embodiment, the first screening module can screen out the linear strong light pattern to obtain the corresponding linear defects. At this time, the screened linear defects include slip defects, and may also include other linear defects such as scratches on the surface of the epitaxial layer.
[0049] Afterwards, the second screening module is used to compare each linear defect with a slip defect model, and linear defects matching the slip defect model are screened out to be determined as slip defects, wherein the slip defect model is simulated according to the crystal orientation of the epitaxial layer.
[0050] Furthermore, the detection system further includes a division module for dividing the epitaxial layer into a plurality of detection areas. The division module can divide the epitaxial layer into regions before the detection light emission module scans the epitaxial layer. In a specific example, the division module can be used to establish polar coordinates with the epitaxial layer as the center point, and divide the epitaxial layer into at least two sectors at a predetermined angle, and further divide each sector into at least two regions along the radial direction of the epitaxial layer with a predetermined size.
[0051] Continue to refer Figure 5 As shown, the detection system also includes a noise filtering module for performing noise filtering on the collected scattered light signal. In this embodiment, the noise filtering module can be specifically used to set a corresponding signal-to-noise ratio threshold S / N (for example, S / N=3:1) for each detection area, and each detection area filters the noise signal based on the corresponding signal-to-noise ratio threshold.
[0052] In addition, the detection system may further include an information integration module, which is used to locate the position of each slip defect in the epitaxial layer after detecting each slip defect, and obtain a distribution map of each slip defect.
[0053] Based on the slip defect detection method described above, a semiconductor processing method is also provided in the present embodiment, which specifically includes: first, forming an epitaxial layer on a wafer, on which a plurality of device areas for preparing semiconductor devices are defined; then, detecting slip defects in the epitaxial layer using the detection method described above; then, determining whether the slip defects fall into more than a predetermined number of device areas; if so, reworking or scrapping the current epitaxial layer; if not, continuing to perform the processing of semiconductor devices on the epitaxial layer.
[0054] That is, in the semiconductor processing method provided by this embodiment, after detecting the slip defect in the epitaxial layer, the distribution of the slip defect can be compared with the distribution of the semiconductor devices to be formed on the epitaxial layer later, so as to determine the amount of impact of the slip defect on the semiconductor devices formed later. When the slip defect only affects a small number of semiconductor devices or has no impact on the semiconductor devices, the subsequent processing process can be continued for the current wafer; when the slip defect affects a large number of semiconductor devices, the current wafer can be reworked or scrapped. In this way, the problem of failure of semiconductor devices formed later due to slip defects can be blocked in time, and the product yield of semiconductor devices formed later on the wafer can be improved.
[0055] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the various embodiments can be referred to each other. For the equipment disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description. Although the present invention has been disclosed as above with preferred embodiments, the above embodiments are not intended to limit the present invention. For any technician familiar with the art, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or modified to equivalent embodiments of equivalent changes. Therefore, any simple modification, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still belong to the scope of protection of the technical solution of the present invention.
[0056] It should also be recognized that the terms described herein are used only to describe specific embodiments and are not intended to limit the scope of the invention. It should be noted that the singular forms "a" and "an" used herein and in the appended claims include plural references unless the context clearly indicates otherwise. For example, a reference to "a step" or "a device" means a reference to one or more steps or devices, and may include secondary steps as well as secondary devices. All conjunctions used should be understood in the broadest sense. And, the word "or" should be understood to have the definition of a logical "or", not a logical "exclusive or", unless the context clearly indicates otherwise.
Claims
1. A method for detecting slip defects in an epitaxial layer, characterized in that: include: Scanning the epitaxial layer on the wafer using the detection light and collecting scattered light signals from the epitaxial layer; Screening out scattered light signals with linear distribution according to the intensity distribution of scattered light to obtain linear defects on the epitaxial layer; and A corresponding slip defect model is simulated according to the crystal orientation of the epitaxial layer, and each linear defect is compared with the slip defect model, wherein a linear defect matching the slip defect model is determined to be a slip defect.
2. The method for detecting slip defects of an epitaxial layer according to claim 1, characterized in that: Before scanning the epitaxial layer, the epitaxial layer is divided into a plurality of detection areas; the detection light scans each detection area of the epitaxial layer to respectively collect scattered light from each detection area.
3. The method for detecting slip defects of an epitaxial layer according to claim 2, characterized in that: The method of dividing the epitaxial layer into a plurality of detection areas comprises: Polar coordinates are established with the center of the epitaxial layer as the pole, and the epitaxial layer is divided into at least two sectors at a predetermined angle, and each sector is further divided into at least two regions with a predetermined size along the radial direction of the epitaxial layer.
4. The method for detecting slip defects of an epitaxial layer according to claim 2, characterized in that: After the scattered light from the epitaxial layer is collected, the method further includes: setting a corresponding signal-to-noise ratio threshold for each detection area, and enabling each detection area to filter noise signals based on the corresponding signal-to-noise ratio threshold.
5. The method for detecting slip defects of an epitaxial layer according to claim 1, characterized in that: After obtaining the slip defects, the method further includes: locating the positions of the slip defects in the epitaxial layer and obtaining a distribution map of the slip defects.
6. The method for detecting slip defects of an epitaxial layer according to claim 1, characterized in that: The slip line in the slip defect model extends along a predetermined angle and a predetermined direction, wherein the linear defect matching the slip defect model is a linear defect extending along a predetermined angle and a predetermined direction matching the slip defect model.
7. A system for detecting slip defects of an epitaxial layer, characterized in that: include: A detection light emitting module, used for emitting detection light to scan the epitaxial layer on the wafer; A scattered light collection module, used for collecting scattered light signals from the epitaxial layer; A first screening module is used to screen out scattered light signals with linear distribution according to the intensity distribution of scattered light, so as to obtain linear defects on the epitaxial layer; and The second screening module is used to compare each linear defect with a slip defect model, and screen out linear defects that match the slip defect model to determine them as slip defects, wherein the slip defect model is simulated according to the crystal orientation of the epitaxial layer.
8. The epitaxial layer slip defect detection system according to claim 7, characterized in that: Also includes: A division module is used to divide the epitaxial layer into a plurality of detection areas.
9. The epitaxial layer slip defect detection system according to claim 8, characterized in that: The division module is used to establish polar coordinates with the epitaxial layer having its center as the pole, divide the epitaxial layer into at least two sectors at a predetermined angle, and further divide each sector into at least two regions with a predetermined size along the radial direction of the epitaxial layer.
10. The epitaxial layer slip defect detection system according to claim 8, characterized in that: Also includes: The noise filtering module is used to set a corresponding signal-to-noise ratio threshold for each detection area, and enable each detection area to filter the noise signal based on the corresponding signal-to-noise ratio threshold.
11. The epitaxial layer slip defect detection system according to claim 8, characterized in that: Also includes: The information integration module is used to locate the position of each slip defect in the epitaxial layer and obtain the distribution map of each slip defect.
12. A semiconductor processing method, characterized in that: include: forming an epitaxial layer on a wafer, wherein a plurality of device regions for preparing semiconductor devices are defined on the epitaxial layer; Detecting slip defects in the epitaxial layer using the slip defect detection method according to any one of claims 1 to 6; It is determined whether the slip defect falls into more than a predetermined number of device regions; if so, rework or scrapping is performed on the current epitaxial layer; if not, the processing of the semiconductor device is continued on the epitaxial layer.