Inspection method for the wafer dicing process

Abstract

To provide an inspection method of a wafer dicing process which can be used in a wafer processing process and can solve the problem of lack of the inspection method in the wafer dicing process.SOLUTION: A method for inspecting a wafer dicing process using a light beam of an optical scanning device to perform a scanning process on a grooved wafer, comprising: using an adhesive layer of the grooved wafer as a light incident surface of the scanning process; performing the scanning process along a Y-axis direction of the grooved wafer to obtain consecutive XZ sectional structural images at different Y-axis positions corresponding to the grooved wafer; analyzing the consecutive XZ sectional structural images at different positions to determine positions corresponding to a plurality of grooves, the adhesive layer, the silicon layer, and the metal layer; and analyzing a depth of each groove to determine whether grooving of the grooved wafer succeeds or fails.SELECTED DRAWING: Figure 10

Description

Technical Field

[0005]

[0001] The present invention relates to a method for inspecting a wafer, and particularly to a method for inspecting a wafer dicing process.

Background Art

[0002] In the current wafer processing process, first, an integrated circuit is formed on a wafer made of a semiconductor material (for example, silicon), and then, by processing the wafer, a number of individual regions are formed, and the individual regions include an integrated circuit called a die (DIE). After the integrated circuit is formed on the wafer, in order to separate the dies on the wafer from each other for use in subsequent processes (for example, packaging), a dicing process may be performed on the wafer.

[0003] In the dicing process, by performing steps such as grooving, scribing, and sawing, a scribed space is formed between each die on the wafer, and then, by performing dicing along the scribed space, the dies on the wafer may be separated from each other. Generally, the scribed space may be called dicing streets.

[0004] In steps such as grooving, scribing, and sawing, there may be structural problems such as cracks and / or fissures in the dicing streets, so there is a possibility of expanding the aforementioned cracks and / or fissures and affecting the quality of the die, and ultimately there is a risk of damaging the integrated circuit in the die.

[0005] This is because, in steps such as grooving, scribing, and sawing, the laser beam used for grooving may experience control problems related to insufficient excitation energy, incident angle deviation, etc., or the dicing cutter may experience control problems related to insufficient dicing force, dicing angle deviation, cutter wear, etc. [Overview of the Initiative] The problem that the invention aims to solve

[0006] Because the current dicing process is performed continuously, steps such as scribing and sawing follow after the groove cutting step is completed. Therefore, damage to integrated circuits within the die due to cracks and / or crack propagation in the dicing street is usually discovered during the die inspection phase, which increases the rate of undetected damage during wafer processing.

[0007] In other words, the inventors have discovered a problem in current dicing processes: the lack of inspection methods. This problem prevents immediate correction of control parameters for the laser beam and dicing cutter when individual steps such as grooving, scribing, and sawing are completed, thus preventing improvement in wafer processing yield. [Means for solving the problem]

[0008] To solve the above problems, an inspection method for a wafer dicing process according to one embodiment of the present invention is an inspection method for a wafer dicing process in which a scanning process is performed on a grooved wafer using a light beam used by an optical scanning device, and includes the steps of: setting the adhesive layer or metal layer of the grooved wafer as the light incident surface for the scanning process; performing the scanning process along the Y-axis direction of the grooved wafer to obtain XZ cross-sectional structural images that are continuous at different Y-axis positions corresponding to the grooved wafer; analyzing the XZ cross-sectional structural images that are continuous at the different Y-axis positions to identify the positions corresponding to a plurality of grooves, the adhesive layer, the silicon layer, and the metal layer; and analyzing the depth of each groove to determine whether the grooving process on the grooved wafer was successful or unsuccessful.

[0009] In one embodiment, if the depth of each groove exceeds the boundary between the silicon layer and the metal layer, the grooving of the grooved wafer is confirmed to be successful; if the depth of each groove does not exceed the boundary between the silicon layer and the metal layer, the grooving of the grooved wafer is confirmed to be unsuccessful.

[0010] In one embodiment, the process includes the step of determining whether the grooving of the grooved wafer was successful or unsuccessful by analyzing the depth of each groove, forming a diced wafer by performing a dicing process on the grooved wafer, using the adhesive layer or metal layer of the diced wafer as the light incident surface for the scanning process, and performing the scanning process on the diced wafer to obtain consecutive XZ cross-sectional structural images or consecutive YZ cross-sectional structural images at different Y-axis positions corresponding to the diced wafer, and further including the process of analyzing the consecutive XZ cross-sectional structural images or consecutive YZ cross-sectional structural images at different Y-axis positions to identify the positions corresponding to multiple dicing streets, the adhesive layer, the silicon layer, the metal layer, and sidewall defects, calculating a maximum depth value based on the maximum depth of the sidewall defects, calculating a thickness value based on the thickness of the silicon layer, and calculating the ratio of the depth of the sidewall defects based on the maximum depth value and the thickness value.

[0011] In one embodiment, the ratio of the depth of the sidewall defect is the maximum depth value / the thickness value × 100%.

[0012] In one embodiment, the process involves analyzing consecutive YZ cross-sectional structural images at different X-axis positions to identify locations corresponding to multiple dicing streets, the adhesive layer, the silicon layer, the metal layer, and sidewall defects; then analyzing each of the dicing streets to identify locations corresponding to the width and depth of the dicing street; and further calculating the aspect ratio of the dicing street based on the width value corresponding to the width of the dicing street and the depth value corresponding to the depth of the dicing street.

[0013] In one embodiment, the aspect ratio of the dicing street is the value of the depth / the value of the width.

[0014] In one embodiment, the process further includes the steps of analyzing each dicing street to identify the position corresponding to the width and depth of the dicing street, calculating a first dicing street perpendicularity based on a first width value corresponding to the width of the dicing street, calculating a second dicing street perpendicularity based on a second width value corresponding to the width of the dicing street, and calculating a dicing street inclination based on the first and second dicing street perpendicularities.

[0015] In one embodiment, based on an XY cross-sectional structural image of the silicon layer, the XY coordinates of a first endpoint corresponding to the left edge of the surface dicing street of the silicon layer and the XY coordinates of a second endpoint corresponding to the right edge of the surface dicing street of the silicon layer are obtained. Based on the XY cross-sectional structural image of the silicon layer, the XY coordinates of a third endpoint corresponding to the left edge of the bottom dicing street of the silicon layer and the XY coordinates of a fourth endpoint corresponding to the right edge of the bottom dicing street of the silicon layer are obtained. The positional displacement of the left dicing street corresponding to the silicon layer is obtained by subtracting the XY coordinates of the first endpoint from the XY coordinates of the third endpoint, and the positional displacement of the right dicing street corresponding to the silicon layer is obtained by subtracting the XY coordinates of the second endpoint from the XY coordinates of the fourth endpoint.

[0016] In one embodiment, after performing the step of setting the adhesive layer or metal layer of the diced wafer as the light incident surface of the scanning process, the scanning process is performed along the X-axis and Y-axis direction of the diced wafer to obtain XY cross-sectional structural images continuous at different Z-axis positions (depths) corresponding to the diced wafer, the location corresponding to the defect region and die edge is identified by analyzing the XY cross-sectional structural images continuous at the different Z-axis positions, the location of the seal ring is determined based on the XY cross-sectional structural image of the metal layer, and it is determined whether the diced wafer contains a normal die or a defective die by analyzing whether the defect region extends beyond the seal ring.

[0017] In one embodiment, if the defect region extends beyond the seal ring, it is confirmed that the diced wafer contains a defective die; if the defect region does not extend beyond the seal ring, it is confirmed that the diced wafer contains a normal die.

[0018] In one embodiment, the step of identifying the location corresponding to the defective region and die edge by analyzing consecutive XY cross-sectional structural images at different Z-axis positions, and then determining whether the diced wafer contains a normal die or a defective die by analyzing whether the defective region is located within the seal ring. [Effects of the Invention]

[0019] In summary, the wafer dicing process inspection method of the present invention involves scanning a grooved wafer or a diced wafer with a light beam used by an optical scanning device to acquire an optical signal, converting the optical signal through an optical image processing device, and then displaying different cross-sectional structural images corresponding to the grooved wafer or diced wafer. This allows for easy observation of the internal structure of the dicing street and, consequently, easy confirmation of the processing quality of the dicing street. [Brief explanation of the drawing]

[0020] [Figure 1] This is a schematic block diagram showing an optical scanning system for performing a scanning process on a grooved wafer in an embodiment of the present invention. [Figure 2] This figure shows the YZ cross-sectional structure image and the XZ cross-sectional structure image in an embodiment of the present invention. [Figure 3] This figure shows an embodiment of the present invention in which a groove processing process and a scanning process are performed on a grooved wafer. [Figure 4] In an embodiment of the present invention, this is a partial XZ cross-sectional structure image corresponding to a grooved wafer, obtained by performing a scanning process on the grooved wafer. [Figure 5] This figure shows an embodiment of the present invention in which a dicing process and a scanning process are performed on a grooved wafer. [Figure 6] This is a partial structural diagram showing that a diced wafer has sidewall defects in an embodiment of the present invention. [Figure 7]In an embodiment of the present invention, it is another partial structural diagram showing a diced wafer. [Figure 8] In an embodiment of the present invention, it is another partial structural diagram showing a diced wafer. [Figure 9] In an embodiment of the present invention, it is a diagram showing the metal layer structure of a diced wafer. [Figure 10] In an embodiment of the present invention, it is a flowchart showing an inspection method for a wafer dicing process (at the grooved stage). [Figure 11] In another embodiment of the present invention, it is a flowchart showing an inspection method for a wafer dicing process (at the diced stage). [Figure 12] In another embodiment of the present invention, it is a flowchart showing an inspection method for a wafer dicing process. [Figure 13A] In yet another embodiment of the present invention, it is a flowchart showing an inspection method for a wafer dicing process. [Figure 13B] In yet another embodiment of the present invention, it is a flowchart showing an inspection method for a wafer dicing process. [Figure 14] In yet another embodiment of the present invention, it is a flowchart showing an inspection method for a wafer dicing process.

Embodiments for Carrying out the Invention

[0021] The following explains the embodiments of the present invention through specific examples, and those skilled in the art can understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through different embodiments, and the details of this specification can be variously modified and changed based on different viewpoints and uses without departing from the spirit of the present invention.

[0022] In embodiments of the present invention, "optical signal" means a luminous beam, a parallel luminous beam, or a focused luminous beam. The luminous beam includes visible light and invisible light (e.g., near-infrared light). Furthermore, "continuous at different positions" means the target coordinate position and its adjacent coordinate positions in the same axis direction, for example, X1, X2, X3, ... on the X axis, Y1, Y2, Y3, ... on the Y axis, or Z1, Z2, Z3, ... on the Z axis.

[0023] Please refer to Figure 1. Figure 1 is a schematic block diagram showing an optical scanning system for performing a scanning process on a grooved wafer 40 in an embodiment of the present invention. The optical scanning system 100 for performing a scanning process on a grooved wafer 40 comprises an optical image processing device 10 and an optical scanning device 20.

[0024] The optical image processing apparatus 10 is arranged to generate a parallel light beam 25 along the first optical axis direction 30. The optical image processing apparatus 10 consists of, but is not limited to, a light beam light source module, an interferometer, a spectrum analyzer, an optical coherence tomography (OCT) system, and a computer. In embodiments of the present invention, the optical image processing apparatus 10 and the optical scanning apparatus 20 can acquire a three-dimensional structural image corresponding to a grooved wafer 40. Since the three-dimensional structural image includes tomographic image data, it can be used to detect and confirm whether or not there are defects outside and inside the grooves of the grooved wafer 40, thereby solving the problem in the prior art of not being able to detect the structure of the dicing street.

[0025] The optical scanning device 20 is connected to the optical image processing device 10. The optical scanning device 20 is configured to convert a light beam 25 along the first optical axis direction 30 into a light beam 25 along the second optical axis direction 32, and to scan the grooved wafer 40 using the light beam 25 along the second optical axis direction 32. The aforementioned "conversion" means converting the direction of propagation of the light beam 25 from a first angle to a second angle. For example, the first angle is 0° and the second angle is 90°. In this embodiment, the first optical axis direction 30 is approximately perpendicular to the second optical axis direction 32.

[0026] The optical signals reflected and / or scattered by the light beam 25 on the surface and inside the grooved wafer 40 are reflected by the first object mirror OL1 and returned to the optical image processing device 10 along the outbound path, where they are subjected to the signal-to-image conversion process. The outbound path can be shown in the following order: optical image processing device 10 → collimator C → light beam scanner S → first lens set LP1 → spectrometer BS → second lens set LP2 → first object mirror OL1. On the other hand, the return path is in the order of first object mirror OL1 → second lens set LP2 → spectrometer BS → first lens set LP1 → light beam scanner S → collimator C → optical image processing device 10. In other embodiments, when the first object mirror OL1 is switched to the second object mirror OL2, the second object mirror OL2 is used instead of the first object mirror OL1 to propagate the light beam along the aforementioned outbound and return paths.

[0027] The optical scanning device 20 comprises a collimator C, a light beam scanner S, a first lens set LP1, a visible light camera module 22a, a second lens set LP2, a first object mirror OL1, and a second object mirror OL2. In this embodiment, the first object mirror OL1 and the second object mirror OL2 can be combined to form an object mirror module. The focus magnification of the object mirror module is adjustable. For example, the focus magnification of the first object mirror OL1 is set to be different from that of the second object mirror OL2. The focus magnification of the first object mirror OL1 can be greater than or less than that of the second object mirror OL2. In other embodiments, the number of object mirrors installed in the object mirror module can be increased or decreased according to the design requirements.

[0028] The collimator C receives the light beam 25 along the first optical axis direction 30 generated by the optical image processing device 10, and is positioned to convert this light beam 25 along the first optical axis direction 30 into a light beam 25 parallel to the first optical axis direction 30. Here, "conversion" means converging the light beam 25 into a light beam 25 parallel to the first optical axis direction 30.

[0029] The optical beam scanner S is positioned at the intersection of the first optical axis direction 30 and the second optical axis direction 32. The optical beam scanner S is positioned to receive the optical beam 25 parallel to the first optical axis direction 30 via the collimator C and to convert the optical beam 25 parallel to the first optical axis direction 30 into an optical beam 25 parallel to the second optical axis direction 32.

[0030] The first lens set LP1 is installed in the second optical axis direction 32. The first lens set LP1 is positioned to diffuse or converge the light beam 25 parallel to the second optical axis direction 32. In this embodiment, the first lens set LP1 is positioned to diffuse the light beam 25 parallel to the second optical axis direction 32.

[0031] The visible light camera module 22a is installed alongside the second optical axis direction 32. The lens direction of the visible light camera module 22a is perpendicular to the second optical axis direction 32. The visible light camera module 22a is positioned to acquire a two-dimensional (XY) surface image corresponding to the adhesive layer 42 of the grooved wafer 40.

[0032] The visible light camera module 22a consists of a camera CAM, a visible light source VIS, and a spectrometer BS. The spectrometer BS may be installed in the second optical axis direction 32. The camera CAM and the visible light source VIS may be installed on either side of the spectrometer BS, respectively. More specifically, the camera CAM is installed on the right side of the second optical axis direction 32, and the visible light source VIS is installed on the left side of the second optical axis direction 32.

[0033] The following describes the operation method of the visible light camera module 22a. The spectrometer BS converts the visible light generated by the visible light source VIS by 90° and directs it into the second lens set LP2. The visible light that has passed through the second lens set LP2 is focused onto the grooved wafer 40 by the first object mirror OL1. The visible light reflected from the grooved wafer 40 is then converted again by 90° by the spectrometer BS and directed to the camera CAM, thereby acquiring and forming a two-dimensional (XY) surface image corresponding to the adhesive layer 42 of the grooved wafer 40. As a result, the optical scanning device 20 can directly acquire a two-dimensional (XY) surface image corresponding to the adhesive layer 42 of the grooved wafer 40 with the visible light camera module 22a. By inspecting the two-dimensional image, the surface condition of the adhesive layer 42 can be understood, and the scanning position and surface condition of the wafer can be confirmed.

[0034] Please refer to Figure 2. Figure 2 shows the YZ cross-sectional structure image and the XZ cross-sectional structure image in an embodiment of the present invention.

[0035] The optical scanning device 20 can acquire a corresponding optical signal by scanning the grooved wafer 40 along the X-axis direction. The optical scanning device 20 can achieve scanning along the X-axis direction with a drive device (not shown). The drive device may be, for example, a linear motor, but is not limited to this. The optical signal is transmitted by the optical scanning device 20 to the optical image processing device 10, where a signal-to-image conversion process is performed to acquire a series of YZ cross-sectional structural images 12 corresponding to different X-axis positions on the grooved wafer 40.

[0036] Similarly, the optical scanning device 20 can acquire the corresponding optical signal by scanning the grooved wafer 40 along the Y-axis. The optical scanning device 20 can achieve scanning along the Y-axis using a drive device (not shown). The optical signal is transmitted by the optical scanning device 20 to the optical image processing device 10, where a signal-to-image conversion process is performed to acquire consecutive XZ cross-sectional structural images 12 corresponding to different Y-axis positions of the grooved wafer 40 (the XZ cross-sectional structural images are omitted in Figure 2 for simplicity).

[0037] The optical image processing device 10 can combine consecutive YZ cross-sectional structural images at different positions or consecutive XZ cross-sectional structural images at different positions to obtain consecutive XY cross-sectional structural images 14 at different positions. This allows the optical image processing device to reconstruct a three-dimensional structural image corresponding to the grooved wafer 40. The three-dimensional structural image may include, but is not limited to, consecutive YZ cross-sectional structural images at different X-axis positions, consecutive XZ cross-sectional structural images at different Y-axis positions, and consecutive XY cross-sectional structural images 14 at different Z-axis positions.

[0038] Furthermore, the optical scanning device 20 can acquire optical signals in the Z-axis direction by scanning the grooved wafer 40. Therefore, it is not necessary to change the Z-axis position of the optical scanning device 20 using a drive device. This improves the convenience of inspection of the grooved wafer 40 and reduces the time required to scan the grooved wafer 40.

[0039] Please refer to Figures 3 and 4 together. Figure 3 is a diagram showing that a groove processing process and a scanning process are performed on a grooved wafer 40 in an embodiment of the present invention, and Figure 4 is a partial XZ cross-sectional structure image corresponding to the grooved wafer obtained by performing a scanning process on the grooved wafer 40 in an embodiment of the present invention. As shown in Figure 3, it is clear that the optical scanning device 20 and the laser head 50 are positioned on different sides of the grooved wafer 40. More specifically, the optical scanning device 20 is positioned on the adhesive layer 42 side of the grooved wafer 40, and the laser head 50 is positioned on the metal layer 46 side of the grooved wafer 40. In other words, the optical scanning device 20 uses the adhesive layer 42 of the grooved wafer 40 as the light incident surface for the scanning process. This is because if the metal layer 46 of the grooved wafer 40 were used as the light incident surface for the scanning process, the optical signal obtained by the reflection of the light beam might be affected. In other embodiments, the optical scanning device 20 can also use the metal layer 46 of the grooved wafer 40 as the light incident surface for the scanning process.

[0040] After the grooving process, it is clear that a first dicing street region 461 and a second dicing street region 462 are formed on the grooved wafer 40. The first dicing street region 461 and the second dicing street region 462 can be formed into grooves 464 and grooves 465 by the laser beam generated by the laser head 50.

[0041] The optical scanning device 20 can perform a scanning process on the grooved wafer 40 and then acquire consecutive XZ cross-sectional structural images at different Y-axis positions corresponding to the grooved wafer 40. As shown in Figure 4, a partial XZ cross-sectional structural image corresponding to the grooved wafer 40 is shown. By analyzing the consecutive XZ cross-sectional structural images at different Y-axis positions, the optical image processing device 10 can identify the positions corresponding to multiple grooves (not shown), an adhesive layer 42, a silicon layer 44, and a metal layer 46. Due to the difference in refractive index between the material and air, the XZ cross-sectional structural image may produce bright lines corresponding to the adhesive layer 42, a bright line corresponding to the surface side 441 of the silicon layer, and a bright line corresponding to the back side 4631 of the metal layer. Therefore, by analyzing the image features within the XZ cross-sectional structural image using an image processing algorithm, the grooves, adhesive layer 42, silicon layer 44, and metal layer 46 can be identified. Next, based on the known actual thicknesses of the adhesive layer 42, silicon layer 44, and metal layer 46 in the grooved wafer 40, the relative relationships between the aforementioned emission lines and the adhesive layer 42, silicon layer 44, and metal layer 46 can be established, thereby further determining the positions of the adhesive layer 42, silicon layer 44, and metal layer 46. In addition, the features of the image cut out by the aforementioned emission lines can be analyzed and identified as the positions of the grooves. This allows for the identification of the positions of the grooves, adhesive layer 42, silicon layer 44, and metal layer 46.

[0042] As shown in Figure 3, if the depth of each groove exceeds the boundary between the silicon layer 44 and the metal layer 46, the grooving of the grooved wafer 40 is confirmed to be successful. For example, if the depth of the groove 464 in the first dicing street region 461 exceeds the boundary between the silicon layer 44 and the metal layer 46, the grooving of the grooved wafer 40 is confirmed to be successful.

[0043] If the depth of any one of the grooves does not exceed the boundary between the silicon layer 44 and the metal layer 46, the grooving of the grooved wafer 40 is confirmed to be a failure. For example, if the depth of the groove 465 in the second dicing street region 462 is shallower than the boundary between the silicon layer 44 and the metal layer 46, the grooving of the grooved wafer 40 is confirmed to be a failure.

[0044] Therefore, the inspection method of the embodiment of the present invention makes it possible to inspect whether the grooving of the grooved wafer 40 has been successful or unsuccessful at the grooving stage. If it is confirmed that the grooving has failed at a certain location, the laser head 50 can be used to re-process the groove 465. This makes it possible to avoid the problem of cracks and / or fissures in the dicing street caused by uneven dicing forces due to defects in the groove 465 in the subsequent dicing process.

[0045] Please refer to Figure 5. Figure 5 shows an embodiment of the present invention in which a dicing process and a scanning process are performed on a grooved wafer 40. As shown in Figure 5, it is clear that the optical scanning device 20 and the dicing cutter 52 are located on different sides of the grooved wafer 40. More specifically, the optical scanning device 20 is located on the adhesive layer 42 side of the grooved wafer 40, and the dicing cutter 52 is located on the metal layer 46 side of the grooved wafer 40. In other embodiments, the optical scanning device 20 and the dicing cutter 52 can be located on the same side of the grooved wafer 40. That is, the optical scanning device 20 uses the metal layer 46 of the grooved wafer 40 as the light incident surface for the scanning process.

[0046] In Figure 5, the groove 465 and adjacent grooves (not shown) in the second dicing street region 462 have already undergone the grooving process again by the laser head 50 so that the depth of groove 465 exceeds the boundary between the silicon layer 44 and the metal layer 46. Therefore, the success of grooving in the second dicing street region 462 is confirmed.

[0047] Please refer to Figure 6. Figure 6 is a partial structural diagram showing a diced wafer 41 in an embodiment of the present invention.

[0048] The grooved wafer 40 is diced by a dicing cutter 52 along the Y direction until it directly penetrates and nearly cuts through the silicon layer 44. If the metal layer 46 is not cut during the dicing stage, the dicing cutter 52 may generate sidewall defects 443 on the dicing surface. The inspection method of the embodiment of the present invention allows for the inspection of the structure and location of the sidewall defects 443, and also allows for the quantification of the depth of the sidewall defects 443 between the silicon layer 44 and the metal layer 46.

[0049] After the dicing process, the optical scanning device 20 performs a scanning process on the diced wafer 41, using the adhesive layer 42 or metal layer 46 of the diced wafer 41 as the light incident surface for the scanning process. By performing a scanning process along the X-axis direction on the diced wafer 41, the optical scanning device 20 acquires consecutive YZ cross-sectional structural images at different positions corresponding to the diced wafer 41, and by analyzing the XZ cross-sectional structure adjacent to the dicing street of the diced wafer, it is possible to check whether or not there are sidewall defects 443. In another embodiment, the optical scanning device 20 can also perform a scanning process along the Y-axis direction on the diced wafer 41, acquire consecutive XZ cross-sectional structural images at different positions corresponding to the diced wafer 41, and by analyzing the YZ cross-sectional structure adjacent to the dicing street of the diced wafer, it is possible to check whether or not there are sidewall defects 443. As shown in Figure 6, it is clear that sidewall defects 443 are generated in the silicon layer 44.

[0050] The optical image processing device 10 can analyze the YZ or XZ cross-sectional structure of a diced wafer that is adjacent to the dicing street and at different locations, and can also identify the locations corresponding to one or more dicing streets (not shown), adhesive layers 42, silicon layers 44, and metal layers 46.

[0051] The optical image processing device 10 can calculate a maximum depth value based on the pixel length corresponding to the maximum depth d of the sidewall defect 443, and can also calculate a thickness value based on the pixel length corresponding to the thickness T of the silicon layer 44. The optical image processing device 10 can calculate the percentage of the sidewall defect depth based on the maximum depth value and the thickness value. The percentage of the sidewall defect depth is maximum depth value / thickness value × 100%. This makes it possible to confirm whether the sidewall defect 443 is in contact with the metal layer 46 through the data of the sidewall defect depth percentage, and consequently, to determine whether the sidewall defect 443 may damage the circuit in the metal layer 46.

[0052] Please refer to Figure 7. Figure 7 is another partial structural diagram showing the diced wafer 41 in an embodiment of the present invention. The optical image processing apparatus 10 can identify the positions corresponding to one or more dicing streets 466, adhesive layers 42, silicon layers 44 and metal layers 46 by analyzing consecutive YZ cross-sectional structural images at different locations.

[0053] The optical image processing device 10 can identify positions corresponding to the width W and depth D of a dicing street by analyzing one or more dicing streets 466.

[0054] The optical image processing apparatus 10 can calculate the aspect ratio of a dicing street based on a width value corresponding to the width W of the dicing street and a depth value corresponding to the depth D of the dicing street. In the embodiment of the present invention, the width value can be calculated by analyzing the pixel length corresponding to the width W of the dicing street, and the depth value can be calculated by analyzing the pixel length corresponding to the depth D of the dicing street. The aspect ratio of the dicing street is the width value / depth value. By providing the user with quantified data of the aspect ratio of the dicing street, it is possible to determine whether the width and depth of the dicing generated at the dicing stage are sufficient or whether they match the set width and depth of the dicing. This makes it possible to evaluate the cutter condition and grasp the subsequent dicing quality. As a result, the dicing process can be improved by replacing the dicing cutter 52 or modifying the control parameters of the dicing cutter 52, and consequently the yield of wafer processing can be improved.

[0055] Please refer to Figure 8. Figure 8 is another partial structural diagram showing a diced wafer 41 in an embodiment of the present invention. The optical image processing apparatus 10 can identify the locations corresponding to one or more dicing streets 467, adhesive layers 42, silicon layers 44 and metal layers 46 by analyzing consecutive YZ cross-sectional structural images at different locations. As shown in Figure 8, it is clear that the dicing street 467 is in a distorted structural state, which may be caused by aging of the dicing cutter 52 or abnormalities in its control parameters.

[0056] The optical image processing device 10 can identify the positions corresponding to the width W and depth D of the dicing street by analyzing the dicing street 467. The optical image processing device 10 can calculate the first dicing street perpendicularity P1 using a first width value W1 corresponding to the width W of the dicing street. The first width value W1 can correspond to the width value of the dicing street exposed on the metal layer surface side 4632. The optical image processing device 10 can calculate the second dicing street perpendicularity P2 using a second width value W2 corresponding to the width W of the dicing street. The second width value W2 can correspond to the width value of the dicing street exposed on the silicon layer surface side 441. The optical image processing device 10 can calculate the dicing street gradient based on the first dicing street perpendicularity P1 and the second dicing street perpendicularity P2.

[0057] In another embodiment, the optical image processing device 10 can obtain a first endpoint XY coordinate 441a corresponding to the left edge of the surface dicing street of the silicon layer 44 and a second endpoint XY coordinate 441b corresponding to the right edge of the surface dicing street of the silicon layer 44, based on an XY cross-sectional structural image of the silicon layer 44. Subsequently, the optical image processing device 10 can obtain a third endpoint XY coordinate 4631a corresponding to the left edge of the bottom surface dicing street of the silicon layer 44 and a fourth endpoint XY coordinate 4631b corresponding to the right edge of the bottom surface dicing street of the silicon layer 44, based on an XY cross-sectional structural image of the silicon layer 44. The optical image processing device 10 can obtain the positional displacement of the left dicing street corresponding to the silicon layer by subtracting the first endpoint XY coordinate 441a from the third endpoint XY coordinate 4631a, and can also obtain the positional displacement of the right dicing street corresponding to the silicon layer by subtracting the second endpoint XY coordinate 441b from the fourth endpoint XY coordinate 4631b.

[0058] By providing users with quantified data on the perpendicularity of the dicing street and the misalignment of the dicing street, it is possible to determine whether or not problems such as aging deterioration of the dicing cutter 52 used in the dicing process or abnormal control parameters are occurring. This allows for improvements to the dicing process by replacing the dicing cutter 52 or correcting its control parameters, thereby improving the yield of wafer processing.

[0059] Please refer to Figure 9. Figure 9 shows the metal layer structure of a diced wafer 41 in an embodiment of the present invention. For convenience of explanation, Figure 9 shows only the structure of the metal layer 46 of the diced wafer 41.

[0060] The optical scanning apparatus 20 can obtain consecutive XY cross-sectional structural images of the diced wafer 41 at different Z-axis positions corresponding to the diced wafer 41 by reconstructing the three-dimensional structure of the wafer through a scanning process along the X and Y axis directions of the diced wafer 41. Similarly, the optical scanning apparatus 20 can use the adhesive layer 42 of the diced wafer 41 as the light incident surface for the scanning process, but is not limited to this. In other embodiments, the optical scanning apparatus 20 can also use the metal layer 46 of the diced wafer 41 as the light incident surface for the scanning process.

[0061] The optical image processing device 10 can identify the locations corresponding to the defect regions 468, 469, 470, 471 and the die edge 56 by analyzing consecutive XY cross-sectional structural images at different Z-axis positions, and can also determine the position of the seal ring 48 based on the XY cross-sectional structural image of the metal layer 46.

[0062] The optical image processing device 10 can determine whether the die on the diced wafer 41 is a normal die or a defective die by analyzing whether the defective regions 468, 469, 470, and 471 extend beyond the seal ring 48.

[0063] If at least one of the defect regions 468, 469, 470, and 471 extends beyond the seal ring 48, it is confirmed that the diced wafer 41 contains a defective die. As shown in Figure 9, all of the defect regions 468, 470, and 471 extend beyond the seal ring 48, and furthermore, the defect region 468 extends to the circuit element 54, so it is confirmed that the diced wafer 41 contains a defective die.

[0064] If none of the defect regions 468, 469, 470, and 471 extend beyond the seal ring 48, it is confirmed that the diced wafer 41 contains a normal die.

[0065] In another embodiment, the optical image processing apparatus 10 can determine whether the diced wafer 41 contains a normal die or a defective die by analyzing whether at least one of the defect regions 468, 469, 470, and 471 is located within the seal ring 48.

[0066] If all of the defect regions 468, 469, 470, and 471 are not located within the seal ring 48, it is confirmed that the diced wafer 41 contains a normal die.

[0067] If at least one of the defect regions 468, 469, 470, and 471 is located within the seal ring 48, it is confirmed that the die in the diced wafer 41 is defective. Thus, the inspection method according to the embodiment of the present invention can be used to inspect whether the die in the diced wafer 41 is normal or defective, thereby improving the versatility of the inspection function.

[0068] Please refer to Figure 10. Figure 10 is a flowchart showing an inspection method for the wafer dicing process (grooved stage) in an embodiment of the present invention. In an embodiment of the present invention, the inspection method for the wafer dicing process involves performing a scanning process on the grooved wafer 40 using the light beam used by the optical scanning device 20, and performing an image analysis process and a data calculation process on the cross-sectional structure image acquired through the scanning process using the optical image processing device 10.

[0069] Step S100 is the step in which the optical scanning apparatus 20 sets the adhesive layer 42 or metal layer 46 of the grooved wafer 40 as the light incident surface for the scanning process.

[0070] Step S110 is a step in which the optical scanning device 20 performs a scanning process along the Y-axis direction of the grooved wafer to acquire consecutive XZ cross-sectional structural images at different Y-axis positions corresponding to the grooved wafer 40.

[0071] Step S112 is the step in which the optical image processing device 10 analyzes consecutive XZ cross-sectional structural images at different Y-axis positions to identify the positions corresponding to multiple grooves, adhesive layers 42, silicon layers 44, and metal layers 46.

[0072] Step S114 is a step in which the optical image processing apparatus 10 analyzes the depth of each groove to determine whether the grooving of the grooved wafer 40 was successful or unsuccessful. If the depth of each groove exceeds the boundary between the silicon layer 44 and the metal layer 46, the grooving of the grooved wafer 40 is confirmed to be successful. If the depth of each groove does not exceed the boundary between the silicon layer 44 and the metal layer 46, the grooving of the grooved wafer 40 is confirmed to be unsuccessful.

[0073] Please refer to Figure 11. Figure 11 is a flowchart of the inspection method for the wafer dicing process (diced stage) in another embodiment of the present invention. In this embodiment, steps S100, S110, and S112 are the same as in the embodiment of Figure 10, so their explanation is omitted. Therefore, in Figure 11, the explanatory blocks for steps S100, S110, and S112 are omitted.

[0074] Step S114 is a step in which the optical image processing apparatus 10 determines whether the grooving of the grooved wafer 40 is successful or unsuccessful by analyzing whether the depth of each groove exceeds the boundary between the silicon layer 44 and the metal layer 46.

[0075] Step S116 is a step in which a dicing process is performed on the grooved wafer 40 to form a diced wafer 41.

[0076] Step S118 is the step in which the optical image processing apparatus 10 makes the adhesive layer 42 or metal layer 46 of the diced wafer 41 the light incident surface for the scanning process.

[0077] Step S119 is a step in which the optical image processing apparatus 10 performs a scanning process on the diced wafer 41 to obtain XZ cross-sectional structural images that are consecutive at different Y-axis positions or YZ cross-sectional structural images that are consecutive at different X-axis positions corresponding to the diced wafer 41.

[0078] Step S120 is a step in which the optical image processing device 10 analyzes consecutive XZ cross-sectional structural images at different Y-axis positions or consecutive YZ cross-sectional structural images at different X-axis positions to identify the locations corresponding to multiple dicing streets, adhesive layers 42, silicon layers 44, metal layers 46, and sidewall defects.

[0079] Step S122 is a step in which the optical image processing apparatus 10 calculates a maximum depth value based on the maximum depth d of the sidewall defect and calculates a thickness value based on the thickness T of the silicon layer 44. In other embodiments, the optical image processing apparatus 10 can calculate a maximum depth value based on the pixel length corresponding to the maximum depth d of the sidewall defect and calculate a thickness value based on the pixel length corresponding to the thickness T of the silicon layer 44.

[0080] Step S124 is a step in which the optical image processing device 10 calculates the ratio of the depth of the sidewall defect based on the maximum depth value and the thickness value. The ratio of the depth of the sidewall defect is (maximum depth value / thickness value) × 100%.

[0081] Please refer to Figure 12. Figure 12 is a flowchart showing an inspection method for the wafer dicing process in another embodiment of the present invention. In this embodiment, steps S114, S116, S118, S119, and S120 are the same as in the embodiment of Figure 11, so their explanation is omitted. Also, in Figure 12, the explanatory blocks for steps S100, S110, and S112 are omitted.

[0082] Step S126 is a step in which the optical image processing device 10 analyzes the dicing street to identify the position corresponding to the width W and depth D of the dicing street.

[0083] Step S128 is a step in which the optical image processing device 10 calculates the aspect ratio of the dicing street based on the width value corresponding to the width W of the dicing street and the depth value corresponding to the depth D of the dicing street. The aspect ratio of the dicing street is the depth value / width value.

[0084] Please refer to Figure 13A. Figure 13A is a flowchart of a wafer dicing process inspection method in another embodiment of the present invention. In this embodiment, steps S114, S116, S118, S119 and S120 are the same as in the embodiment of Figure 11, so their explanation is omitted. Also, in Figure 13A, the explanatory blocks for steps S100, S110, S112, S114, S116, S118 and S119 are omitted.

[0085] Step S130 is a step in which the optical image processing device 10 calculates the first dicing street perpendicularity P1 based on a first width value W1 corresponding to the width W of the dicing street.

[0086] Step S132 is a step in which the optical image processing device 10 calculates the second dicing street perpendicularity P2 based on a second width value W2 corresponding to the width W of the dicing street.

[0087] Step S134 is a step in which the optical image processing device 10 calculates the dicing street gradient based on the first dicing street perpendicularity P1 and the second dicing street perpendicularity P2.

[0088] Please refer to Figure 13B. Figure 13B is a flowchart of a wafer dicing process inspection method in another embodiment of the present invention. In this embodiment, steps S114, S116, S118, S119 and S120 are the same as in the embodiment of Figure 11, so their explanation is omitted. Also, in Figure 13B, the explanatory blocks for steps S100, S110, S112, S114, S116, S118 and S119 are omitted.

[0089] Step S126 is a step in which the optical image processing device 10 analyzes the dicing street to identify the position corresponding to the width W and depth D of the dicing street.

[0090] Step S1261 is a step in which the optical image processing device 10 obtains a first endpoint XY coordinate 441a corresponding to the left edge of the surface dicing street of the silicon layer 44 and a second endpoint XY coordinate 441b corresponding to the right edge of the surface dicing street of the silicon layer 44, based on an XY cross-sectional structural image of the silicon layer 44.

[0091] Step S1262 is a step in which the optical image processing device 10 obtains the XY coordinates 4631a of a third endpoint corresponding to the left edge of the bottom dicing street of the silicon layer 44 and the XY coordinates 4631b of a fourth endpoint corresponding to the right edge of the bottom dicing street of the silicon layer 44, based on the XY cross-sectional structural image of the silicon layer 44.

[0092] Step S1263 is a step in which the optical image processing device 10 subtracts the first endpoint XY coordinate 441a from the third endpoint XY coordinate 4631a to obtain the positional displacement of the left dicing street corresponding to the silicon layer, and subtracts the second endpoint XY coordinate 441b from the fourth endpoint XY coordinate 4631b to obtain the positional displacement of the right dicing street corresponding to the silicon layer.

[0093] Please refer to Figure 14. Figure 14 is a flowchart of a wafer dicing process inspection method in another embodiment of the present invention. In this embodiment, steps S114, S116, and S118 are the same as in the embodiment of Figure 11, so their explanation is omitted. Also, in Figure 14, the explanatory blocks for steps S100, S110, and S112 are omitted.

[0094] Step S136 is a step in which a scanning process is performed along the X-axis and Y-axis directions of the diced wafer 41 to obtain consecutive XY cross-sectional structural images at different Z-axis positions corresponding to the diced wafer 41.

[0095] Step S138 is a step in which the optical image processing apparatus 10 analyzes consecutive XY cross-sectional structural images at different Z-axis positions to identify the locations corresponding to defect regions 468, 469, 470, 471 and the die edge, and also determines the position of the seal ring 48 based on the XY cross-sectional structural images of the metal layer 46. In this embodiment, the locations and number of defect regions 468, 469, 470 and 471 are merely examples and do not limit the locations and number of defect regions.

[0096] Step S140 is a step in which the optical image processing apparatus 10 determines whether the diced wafer 41 contains a normal die or a defective die by analyzing whether the defective regions 468, 469, 470, and 471 extend beyond the seal ring 48. If at least one of the defective regions 468, 469, 470, and 471 extends beyond the seal ring 48, it is confirmed that the diced wafer 41 contains a defective die. If none of the defective regions 468, 469, 470, and 471 extend beyond the seal ring 48, it is confirmed that the diced wafer 41 contains a normal wafer.

[0097] In another embodiment, the optical image processing apparatus 10 can determine whether the diced wafer 41 contains a normal die or a defective die by analyzing whether at least one of the defect regions 468, 469, 470, and 471 is located within the seal ring 48. If at least one of the defect regions 468, 469, 470, and 471 is located within the seal ring 48, it is confirmed that the diced wafer 41 contains a defective die. If all of the defect regions 468, 469, 470, and 471 are not located within the seal ring 48, it is confirmed that the diced wafer 41 contains a normal die.

[0098] As described above, the wafer dicing process inspection method of the present invention involves scanning a grooved wafer or a diced wafer with a light beam used by an optical scanning device to acquire an optical signal, converting the optical signal through an optical image processing device, and then displaying information corresponding to different cross-sectional structural images of the grooved wafer or the diced wafer. This allows for easy observation of the internal structure of the dicing street and, consequently, easy confirmation of the processing quality of the dicing street.

[0099] The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included within the technical scope of the present invention. [Explanation of symbols]

[0100] 10 Optical image processing device 20 Optical scanning device 22a Visible light camera module 25 luminous flux 30 First optical axis direction 32 Second optical axis direction 40 grooved wafers 41 Diced wafers 42 Adhesive layer 44 Silicon Layers 441 Silicon layer surface side 441a 1st end point XY coordinates 441b Second end point XY coordinates 443 Sidewall defects 46 Metal layer 461 1st Dicing Street Area 462 Second Dicing Street Area 4631 Back side of the metal layer 4631a 3rd end point XY coordinates 4631b 4th end point XY coordinates 4632 Metal layer surface side 464~465 Groove 466-467 Dicing Street 468-471 Defect area 48 sealing rings 50 laser heads 52 Dicing Cutter 54 Circuit Elements 56 Die Edge BS spectrometer C collimator CAM camera d Maximum depth D. Depth of Dicing Street LP1 1st Lens Set LP2 2nd Lens Set OL1 First Object Mirror OL2 Second Object Mirror P1 1st Dicing Street Perpendicularity P2 Second Dicing Street Perpendicularity S Light Beam Scanner T thickness VIS visible light source W Dicing Street width W1 First width value W2 Second width value S100, S110, S112, S114 Step S116, S118, S119 Step S120, S122, S124 Step S126, S128, S130 Step S132, S134, S136 Step S138, S140 Step S1261~S1263 Step

Claims

1. An inspection method for a wafer dicing process, in which a scanning process is performed on a grooved wafer using a light beam used by an optical scanning device, The steps include making the adhesive layer or metal layer of the grooved wafer the light incident surface for the scanning process, The steps include: performing the scanning process along the Y-axis direction of the grooved wafer to obtain consecutive XZ cross-sectional structural images at different Y-axis positions corresponding to the grooved wafer; The steps include: identifying the positions corresponding to multiple grooves, the adhesive layer, the silicon layer, and the metal layer by analyzing consecutive XZ cross-sectional structural images at different Y-axis positions; The steps include: determining whether the grooving process on the grooved wafer was successful or unsuccessful by analyzing the depth of each groove; The steps include: forming a diced wafer by performing a dicing process on the grooved wafer; The steps of making the adhesive layer or metal layer of the diced wafer the light incident surface for the scanning process, The steps include performing the scanning process on the diced wafer to obtain consecutive XZ cross-sectional structural images at different Y-axis positions or consecutive YZ cross-sectional structural images at different X-axis positions corresponding to the diced wafer, The steps include: identifying the locations corresponding to multiple dicing streets, the adhesive layer, the silicon layer, the metal layer, and sidewall defects by analyzing XZ cross-sectional structural images that are continuous at different Y-axis positions or YZ cross-sectional structural images that are continuous at different X-axis positions; The steps include: calculating the maximum depth value based on the maximum depth of the sidewall defect, and calculating the thickness value based on the thickness of the silicon layer; A step of calculating the ratio of the depth of the sidewall defect based on the maximum depth value and the thickness value, A method for inspecting the wafer dicing process, including [the specified part of the process].

2. If the depth of each groove exceeds the boundary between the silicon layer and the metal layer, the groove processing of the grooved wafer is confirmed to be successful. An inspection method for a wafer dicing process according to claim 1, wherein if the depth of each groove does not exceed the boundary between the silicon layer and the metal layer, it is confirmed that the grooving process on the grooved wafer has failed.

3. The maximum depth value and the thickness value are calculated based on the pixel length corresponding to the maximum depth and the pixel length corresponding to the thickness. A method for inspecting a wafer dicing process according to claim 1.

4. The inspection method for a wafer dicing process according to claim 1, wherein the ratio of the depth of the sidewall defect is the maximum depth value / the thickness value × 100%.

5. After performing the step of identifying the locations corresponding to multiple dicing streets, the adhesive layer, the silicon layer, the metal layer, and sidewall defects by analyzing consecutive YZ cross-sectional structural images at different X-axis positions, By analyzing each of the dicing streets, the positions corresponding to the width and depth of the dicing street are identified. The method for inspecting a wafer dicing process according to claim 1, further comprising calculating the aspect ratio of the dicing street based on a width value corresponding to the width of the dicing street and a depth value corresponding to the depth of the dicing street.

6. The inspection method for a wafer dicing process according to claim 5, wherein the aspect ratio of the dicing street is the value of the depth / the value of the width.

7. After performing the step of analyzing each of the dicing streets to identify the positions corresponding to the width and depth of the dicing street, The first dicing street perpendicularity is calculated based on the first width value corresponding to the width of the dicing street. The second dicing street perpendicularity is calculated based on a second width value corresponding to the width of the aforementioned dicing street. The method for inspecting a wafer dicing process according to claim 5, further comprising calculating a dicing street inclination based on the first dicing street perpendicularity and the second dicing street perpendicularity.

8. After performing the step of analyzing each of the dicing streets to identify the positions corresponding to the width and depth of the dicing street, Based on the XY cross-sectional structural image of the silicon layer, the XY coordinates of the first endpoint corresponding to the left edge of the surface dicing street of the silicon layer and the XY coordinates of the second endpoint corresponding to the right edge of the surface dicing street of the silicon layer are obtained. Based on the XY cross-sectional structural image of the silicon layer, the XY coordinates of the third endpoint corresponding to the left edge of the bottom dicing street of the silicon layer and the XY coordinates of the fourth endpoint corresponding to the right edge of the bottom dicing street of the silicon layer are obtained. The wafer dicing process inspection method according to claim 5, further comprising subtracting the first endpoint XY coordinates from the third endpoint XY coordinates to obtain the positional displacement of the left dicing street corresponding to the silicon layer, and subtracting the second endpoint XY coordinates from the fourth endpoint XY coordinates to obtain the positional displacement of the right dicing street corresponding to the silicon layer.

9. After performing the step of making the adhesive layer or metal layer of the diced wafer the light incident surface of the scanning process, By performing the scanning process along the X and Y axis directions of the diced wafer, consecutive XY cross-sectional structural images are obtained at different Z-axis positions corresponding to the diced wafer. By analyzing consecutive XY cross-sectional structural images at different Z-axis positions, the locations corresponding to the defect region and die edge are identified, and the position of the seal ring is determined based on the XY cross-sectional structural images of the metal layer. The inspection method for a wafer dicing process according to claim 1, further comprising determining whether the diced wafer contains a normal die or a defective die by analyzing whether the defective region extends beyond the seal ring.

10. If the defect region extends beyond the seal ring, it is confirmed that the diced wafer contains a defective die. The inspection method for a wafer dicing process according to claim 9, wherein if the defect region does not extend beyond the seal ring, it is confirmed that the diced wafer contains a normal die.

11. A method for inspecting a wafer dicing process according to claim 9, further comprising the steps of: identifying the location corresponding to the defective region and the die edge by analyzing consecutive XY cross-sectional structural images at different Z-axis positions; and determining whether the diced wafer contains a normal die or a defective die by analyzing whether the defective region is located within the seal ring.

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