Wafer detection method and wafer processing system

Abstract

The invention provides a wafer detection method and a wafer processing system, and the method comprises the steps: scanning the edge of a wafer through laser, and obtaining a scanning signal; obtaining first data according to the scanning signal, wherein the first data represents the edge morphology of the wafer; and judging whether the first data is in a preset range, and if the first data is not in the preset range, determining that the edge of the wafer has defects. According to the detection method, the wafers with edge defects can be eliminated before the wafers enter the cavity of the process equipment, so that the yield of products is improved, and the production cost is reduced.

Description

Technical Field

[0001] The present disclosure relates to the technical field of semiconductor devices, and more specifically, to a wafer detection method and a wafer processing system. Background Art

[0002] In the field of semiconductor manufacturing, the problem of wafer edge chipping is a long-standing technical problem. As the basic material of semiconductor devices, the integrity of wafers is crucial to the entire manufacturing process. The chipping of wafer edges not only leads to the scrapping of a single wafer, but may also affect the quality of the entire batch of wafers, which in turn has a serious impact on the yield and quality of semiconductor devices.

[0003] Wafer edge chipping can be caused by a variety of factors, including material properties, stringent process control, residual stress, etc. For example, third-generation semiconductor materials such as silicon carbide (SiC) and gallium nitride (GaN) are known for their high hardness, high brittleness and high chemical stability, which make it very easy to crack, break or surface damage during grinding and polishing. The stringency of process control is also an important factor. The wafer grinding and polishing process includes multiple stages such as cutting, grinding and polishing, and each stage has extremely high requirements for process control. Any slight deviation may cause the wafer quality to fail to meet the standard, which in turn affects the manufacturing quality of subsequent integrated circuits.

[0004] Wafer edge chipping is often difficult to detect before the wafer enters the process equipment chamber. Wafer edge chipping not only leads to waste of process costs in the equipment chamber, but also reduces the wafer yield. Since the wafer edge chipping problem is not discovered until the late stage of the process, it is difficult to trace the specific cause of the problem, which increases the difficulty of process optimization. Summary of the invention

[0005] In view of the above problems, the purpose of the present disclosure is to provide a wafer inspection method and a wafer processing system, which improves the product yield and reduces the production cost by eliminating wafers with edge defects before the wafers enter the chamber of the process equipment.

[0006] According to one aspect of an embodiment of the present disclosure, a wafer detection method is provided, including:

[0007] Use laser to scan the edge of the wafer to obtain scanning signals;

[0008] Acquire first data according to the scanning signal, wherein the first data represents the edge morphology of the wafer;

[0009] It is determined whether the first data is within a preset range. If the determination result is no, there is a defect at the edge of the wafer.

[0010] Optionally, the scanning signal includes a light intensity signal received by a laser sensor.

[0011] Optionally, the laser sensor and the laser source are located on opposite sides of the wafer and do not contact the wafer.

[0012] The laser sensor receives the light not blocked by the wafer and the transmitted light of the laser passing through the wafer.

[0013] Optionally, the laser sensor and the laser source are located on the same surface of the wafer, and the laser sensor is used to receive reflected light irradiated on the wafer; or

[0014] There are multiple laser sensors, which are located on two opposite sides of the wafer. The laser sensor on one side is used to receive reflected light irradiated on the wafer, and the laser sensor on the other side is used to receive light not blocked by the wafer.

[0015] Optionally, the first data includes pixel values ​​obtained according to the light intensity signal.

[0016] Optionally, it also includes:

[0017] Obtaining a mapping relationship table between the pixel value and the edge width of the wafer irradiated by the laser; and

[0018] The actual edge width of the wafer irradiated by the laser is obtained according to the mapping relationship table and the acquired pixel value.

[0019] Optionally, the first data includes a width of an edge of a wafer irradiated by the laser, obtained based on the light intensity signal.

[0020] Optionally, in the step of determining whether the first data is within a preset range, the influence of the data of the positioning groove or the positioning edge of the wafer is excluded.

[0021] Optionally, it also includes:

[0022] Acquire the position of the positioning groove or positioning edge of the wafer according to the first data; and

[0023] The wafer is rotated to a preset direction according to the positioning groove or the positioning edge.

[0024] According to another aspect of an embodiment of the present disclosure, a wafer processing system is provided, which can use the above-mentioned detection method to detect wafers.

[0025] Optionally, the wafer processing system comprises:

[0026] A rotating shaft, used to drive the wafer to rotate;

[0027] A light source for generating laser light;

[0028] A laser sensor for receiving light intensity signals;

[0029] The data processing unit is used to obtain first data characterizing the edge morphology of the wafer according to the light intensity signal received by the laser sensor.

[0030] Optionally, a robot arm and a locking portion are further included, wherein when it is detected that an edge of the wafer has a defect, the robot arm is used to move the wafer with the defective edge to the locking portion.

[0031] One of the above technical solutions has the following beneficial effects:

[0032] By using laser scanning on the edge of the wafer, part of the light is irradiated onto the surface close to the edge of the wafer, and the other part of the light is not blocked and is irradiated onto the outside of the edge of the wafer. The first data characterizing the edge morphology of the wafer is obtained based on the scanning signal. If there is no chipping / crushing problem on the edge of the wafer, the first data corresponding to a circle of the wafer edge are basically the same. If there is a chipping / crushing problem, the first data corresponding to one or more places on the edge of the wafer will show obvious fluctuations, so that it can be judged that there are defects on the edge of the wafer. Before the wafer enters the chamber of the process equipment, these wafers with edge defects are pre-eliminatd, thereby improving the product yield and reducing production costs.

[0033] In some embodiments, the scanning signal includes a light intensity signal received by the laser sensor, and the first data includes a pixel value obtained according to the light intensity signal, or a width value of an edge of a wafer irradiated by laser obtained according to the light intensity signal.

[0034] In some embodiments, a mapping relationship table between pixel values ​​and the edge width of the wafer irradiated by the laser is obtained in advance. After the edge of the wafer is irradiated with the laser, a table lookup is performed to obtain the width of a circle of the edge of the wafer actually irradiated by the laser according to the mapping table. If there is a problem of fragmentation / breakage at the edge of the wafer, the irradiation width at one or more locations on the edge of the corresponding wafer will be reduced or have no value, thereby further understanding the degree of fragmentation / breakage and providing reference data for subsequent process improvements.

[0035] It should be noted that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present disclosure, rather than limiting the present disclosure.

[0037] Figure 1 A schematic structural diagram of a wafer processing system according to an embodiment of the present disclosure is shown;

[0038] Figure 2 Shows Figure 1 A schematic diagram of a portion of the structure used for detecting wafers in a wafer processing system;

[0039] Figures 3 to 5 A schematic diagram showing the principle of wafer detection according to an embodiment of the present disclosure is shown;

[0040] Figure 6 A schematic diagram of a curve showing wafer rotation angle and pixel value is shown;

[0041] Figure 7 A schematic diagram of a curve showing wafer rotation angle and edge detection width is shown. DETAILED DESCRIPTION

[0042] The present disclosure will be described in more detail below with reference to the accompanying drawings. In each of the drawings, the same elements are represented by similar reference numerals. For the sake of clarity, the various parts in the drawings are not drawn to scale. In addition, some well-known parts may not be shown. For the sake of simplicity, the semiconductor structure obtained after several steps can be described in one figure.

[0043] It should be understood that when describing the structure of a device, when a layer or a region is referred to as being "on" or "over" another layer or another region, it may mean that it is directly on the other layer or another region, or that other layers or regions are included between it and the other layer or another region. Furthermore, if the device is turned over, the layer or a region will be "below" or "beneath" another layer or another region.

[0044] If the purpose is to describe the situation of being directly on another layer or another area, this article will use expressions such as "directly on..." or "on... and adjacent to...".

[0045] Many specific details of the present disclosure are described below, such as device structure, materials, dimensions, processing technology and techniques, so as to more clearly understand the present disclosure. However, as those skilled in the art will appreciate, the present disclosure may not be implemented in accordance with these specific details.

[0046] Figure 1 A schematic structural diagram of a wafer processing system according to an embodiment of the present disclosure is shown.

[0047] See also Figure 1 The wafer processing system in the embodiment of the present disclosure includes: a front-opening wafer transfer box (FOUP) 10, an operating table 20, a robot arm 30, a wafer detection module 40, a locking part 50, a loading chamber 61, an unloading chamber 62, a transfer chamber 70, a process chamber 80 and a control module.

[0048] The wafer transfer box 10 is located on one side of the operating table 20; the loading chamber 61, the unloading chamber 62, the transfer chamber 70 and the process chamber 80 are located on the other side of the operating table 20; the robot arm 30, the wafer detection module 40 and the locking part 50 are located on the operating table 20.

[0049] After the wafer transport box 10 is loaded with wafers and transported to the operating table 20, the robot arm 30 takes out each wafer in turn and sends it to the wafer inspection module 40. The wafer inspection module 40 detects whether there are defects on the edge of the wafer. If there are defects, the robot arm 30 moves the wafer to the locking part 50; if there are no defects, the wafer inspection module 40 will rotate the wafer to a predetermined direction according to the positioning groove (Notch) or positioning edge on the wafer, and then the robot arm 30 moves the wafer to the loading chamber 61, and the robot in the transport chamber 70 will transfer the wafer in the loading chamber 61 to the process chamber 80. Among them, the process chamber 80 performs, for example, deposition process, etching process, glue coating process, exposure process, annealing process, polishing process, ion implantation process, etc. After the process of this step is completed, the robot in the transport chamber 70 will transfer the wafer in the process chamber 80 to the unloading chamber 62, and finally the robot arm 30 will transfer the wafer to the wafer transport box 10, and the wafer transport box 10 will transport the wafer to the next process node. The above process can be controlled and executed by the control module.

[0050] Figure 2 Shows Figure 1 Schematic diagram of a part of the structure used to detect wafers in a wafer processing system. Figures 3 to 5 A schematic diagram showing the principle of wafer detection according to an embodiment of the present disclosure is shown.

[0051] See also Figures 2 to 4 The wafer inspection module 40 includes a rotating shaft 41 , a housing 42 , a light source, laser sensors 43 / 44 and a data processing unit 45 .

[0052] The rotating shaft 41 extends out of the operating table 20 to drive the wafer 100 above it to rotate. Optionally, the rotating shaft 41 is a wafer aligner that uses a micro sensor for precise correction.

[0053] The shell 42 is in an upright “concave” shape and is located on the operating table 20 . The edge of the wafer 100 can be located in the concave of the shell 42 without contacting the shell 42 .

[0054] The light source and the laser sensor 43 / 44 are both disposed in the housing 42 , wherein the light source is located obliquely above the rotation axis 41 , and the generated laser can irradiate the edge of the wafer 100 .

[0055] In some embodiments, when the wafer 100 is an opaque wafer, there will be reflected light after the laser irradiates the surface of the wafer 100. Figure 3The dashed arrow in represents the reflected light, and the laser sensor 43 located above the wafer 100 receives the reflected light. For example, the opaque wafer material may be silicon.

[0056] In some embodiments, when the wafer 100 is a transparent wafer, the laser irradiates the upper surface of the wafer 100 and then transmits out from the lower surface. Figure 4 The dashed arrow in represents the transmitted light, and the laser sensor 44 located below the wafer 100 receives the transmitted light and the light not blocked by the wafer 100. For example, the opaque wafer material may be silicon carbide, gallium nitride, and the like.

[0057] The data processing unit 45 is used to obtain first data representing the edge morphology of the wafer 100 according to the light intensity signal received by the laser sensor 43 / 44 .

[0058] In some other embodiments, laser sensors 43 and 44 may also be provided simultaneously. For example, when wafer 100 is an opaque wafer, laser sensor 43 located above wafer 100 receives reflected light, and laser sensor 44 located below wafer 100 receives light not blocked by wafer 100 .

[0059] The following describes in detail the wafer detection method of the embodiment of the present disclosure by taking the example of only setting the laser sensor 43 .

[0060] See also Figure 5 The edge of the wafer 100 has a positioning groove 120 and a fragmentation area 130, and the width of the edge area 110 irradiated by the laser is d.

[0061] The edge of the wafer 100 is irradiated with laser, and the control module controls the rotating shaft 41 to drive the wafer 100 to rotate, so that the laser scans the edge of the wafer 100 in one circle to obtain a scanning signal. The reflected light irradiated by the laser on the wafer 100 is received by the laser sensor 43, wherein the scanning signal includes the light intensity signal received by the laser sensor 43.

[0062] The data processing unit 45 obtains the pixel value representing the edge morphology of the wafer according to the light intensity signal received by the laser sensor 43, and obtains Figure 6 The curve shown, where Figure 6 The horizontal axis represents the rotation angle of the wafer, and the vertical axis represents the pixel value.

[0063] According to Figure 6 The curve shown can determine whether the pixel value is within a preset range. For example, the preset range of the pixel value is set at around 1000. When the wafer 100 is rotated to -60° to -40°, the pixel value is significantly reduced and is not within the preset range. Therefore, it can be determined that there is a defect at the edge of the wafer 100.

[0064] In the step of determining whether the pixel value is within the preset range, it is necessary to exclude the data influence of the positioning groove 120 (or positioning edge) of the wafer 100. Specifically, since the pixel value at the positioning groove 120 is fixed and can be set in advance, the morphology of the positioning groove 120 is very regular, and the probability that the edge defect is consistent with the morphology of the positioning groove 120 is extremely low, and the probability that the pixel value corresponding to the edge defect is consistent with the pixel value corresponding to the positioning groove 120 is also extremely low.

[0065] Furthermore, if the wafer under test is qualified, the position of the positioning groove 120 of the wafer can be obtained according to the pixel value, and then the wafer can be rotated to a preset direction according to the positioning groove 120. It can also be executed by setting an interlock (Inter Lock) on the alarm unit and the Fault Detection and Classification (FDC) unit in the wafer processing system through the prepared test data.

[0066] In some preferred embodiments, a mapping relationship table between pixel values ​​and the edge width of the wafer irradiated by the laser is pre-set in the data processing unit 45. In the actual detection process, the edge width d of the wafer irradiated by the laser can be obtained according to the mapping relationship table and the obtained pixel values. Figure 7 The curve shown, where Figure 7 The horizontal axis represents the rotation angle of the wafer, and the vertical axis represents the width d of the wafer edge irradiated by the laser.

[0067] In some optional embodiments, it can also be determined whether the edge width d is within a preset range. If the determination result is no, there is a defect at the edge of the wafer. Figure 7 For example, the maximum value of the edge width d is set to 9 and the minimum value is set to 7. When the wafer 100 rotates to -60° to -40°, the edge width d is between 4 and 6, which is not within the preset range. Therefore, it can be determined that there is a defect at the edge of the wafer 100. Of course, the influence of the positioning groove 120 also needs to be excluded in advance.

[0068] In some optional embodiments, it can also be determined whether the edge fragmentation value is within a preset range. If the determination result is no, the edge of the wafer has a defect. For example, the mapping value of the laser scanning signal is the edge width d, the edge width of the laser scanning is 9, and the edge fragmentation value is 9-d. The normal edge fragmentation value is set between 0 and 2. When the edge fragmentation value obtained is greater than 2, it is not within the preset range. Therefore, it can be determined that the edge of the wafer 100 has a defect. Of course, the influence of the positioning groove 120 also needs to be excluded in advance.

[0069] By directly judging the edge width d, the degree of edge fragmentation can be more intuitively obtained. For example, in this embodiment, when the wafer 100 rotates to -60° to -40°, the edge width d is between 4 and 6, and the edge fragmentation value can be directly obtained to be between 1 and 5, which provides a more intuitive display of the degree of edge fragmentation.

[0070] One of the above technical solutions has the following beneficial effects:

[0071] By using laser scanning on the edge of the wafer, part of the light is irradiated onto the surface close to the edge of the wafer, and the other part of the light is not blocked and is irradiated onto the outside of the edge of the wafer. The first data characterizing the edge morphology of the wafer is obtained based on the scanning signal. If there is no chipping / crushing problem on the edge of the wafer, the first data corresponding to a circle of the wafer edge are basically the same. If there is a chipping / crushing problem, the first data corresponding to one or more places on the edge of the wafer will show obvious fluctuations, so that it can be judged that there are defects on the edge of the wafer. Before the wafer enters the chamber of the process equipment, these wafers with edge defects are pre-eliminatd, thereby improving the product yield and reducing production costs.

[0072] In some embodiments, the scanning signal includes a light intensity signal received by the laser sensor, and the first data includes a pixel value obtained according to the light intensity signal, or a width value of an edge of a wafer irradiated by laser obtained according to the light intensity signal.

[0073] In some embodiments, a mapping relationship table between pixel values ​​and the edge width of the wafer irradiated by the laser is obtained in advance. After the edge of the wafer is irradiated with the laser, a table lookup is performed to obtain the width of a circle of the edge of the wafer actually irradiated by the laser according to the mapping table. If there is a problem of fragmentation / breakage at the edge of the wafer, the irradiation width at one or more locations on the edge of the corresponding wafer will be reduced or have no value, thereby further understanding the degree of fragmentation / breakage and providing reference data for subsequent process improvements.

[0074] In addition, the wafer edge breakage and chipping can be detected before the wafer enters the process chamber, so measures can be taken in advance to reduce equipment downtime and improve equipment utilization. Since the damaged wafer does not enter the process chamber, the cost of production maintenance (PM) of the equipment can be saved.

[0075] The embodiments of the present disclosure are described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present disclosure. The scope of the present disclosure is defined by the appended claims and their equivalents. Without departing from the scope of the present disclosure, a person skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A wafer inspection method, comprising: Use laser to scan the edge of the wafer to obtain scanning signals; Acquire first data according to the scanning signal, wherein the first data represents the edge morphology of the wafer; It is determined whether the first data is within a preset range. If the determination result is no, there is a defect at the edge of the wafer.

2. The detection method according to claim 1, wherein: The scanning signal includes a light intensity signal received by the laser sensor.

3. The detection method according to claim 2, wherein: The laser sensor and the laser source are located on two opposite sides of the wafer. The laser sensor is used to receive the light that is not blocked by the wafer and the transmitted light of the laser passing through the wafer.

4. The detection method according to claim 2, wherein: The laser sensor and the laser source are located on the same surface of the wafer, and the laser sensor is used to receive reflected light irradiated on the wafer; or There are multiple laser sensors, which are located on two opposite sides of the wafer. The laser sensor on one side is used to receive reflected light irradiated on the wafer, and the laser sensor on the other side is used to receive light not blocked by the wafer.

5. The detection method according to any one of claims 2 to 4, wherein: The first data includes pixel values ​​obtained according to the light intensity signal.

6. The detection method according to claim 5, wherein: Also includes: Obtaining a mapping relationship table between the pixel value and the edge width of the wafer irradiated by the laser; as well as The actual edge width of the wafer irradiated by the laser is obtained according to the mapping relationship table and the acquired pixel value.

7. The detection method according to any one of claims 2 to 4, wherein: The first data includes the edge width of the wafer irradiated by the laser, which is obtained according to the light intensity signal.

8. The detection method according to any one of claims 1 to 4, wherein: In the step of determining whether the first data is within a preset range, the data influence of the positioning groove or positioning edge of the wafer is excluded.

9. The detection method according to any one of claims 1 to 4, further comprising: Acquire the position of the positioning groove or positioning edge of the wafer according to the first data; as well as The wafer is rotated to a preset direction according to the positioning groove or the positioning edge.

10. A wafer processing system capable of detecting wafers using the detection method according to any one of claims 1 to 9.

11. The wafer processing system according to claim 10, comprising: A rotating shaft, used to drive the wafer to rotate; A light source for generating laser light; A laser sensor for receiving light intensity signals; The data processing unit is used to obtain first data characterizing the edge morphology of the wafer according to the light intensity signal received by the laser sensor.

12. The wafer processing system according to claim 10 or 11, further comprising a robot arm and a locking portion, wherein: When it is detected that the edge of the wafer has a defect, the robot arm is used to move the wafer with the defective edge to the locking portion.

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