JP7349841B2 - Chip manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a chip.

As a method of dividing workpieces such as semiconductor device wafers, a modified layer is formed by irradiating a focused point of a laser beam with a wavelength that is transparent to the workpiece by positioning it inside the workpiece. A technique is known in which the modified layer is divided as a fracture starting point (see Patent Document 1). The laser processing apparatus used for the above laser processing can easily switch between irradiation and non-irradiation of the laser beam. Therefore, it is possible to process wafers in which streets are disposed discontinuously, such as multi-project wafers in which devices of different shapes and sizes are mixed (see Patent Document 2). When performing laser processing on such a multi-project wafer, it is necessary to set in advance conditions such as the XY coordinate values of a location to be irradiated or not irradiated with a laser beam in the laser processing apparatus. A technique for visually detecting whether or not set conditions are correct has also been proposed (see Patent Document 3).

Japanese Patent Application Publication No. 2002-192370 Japanese Patent Application Publication No. 2010-123723 Japanese Patent Application Publication No. 2015-020177

Incidentally, conditions such as the chip size and the XY coordinate values of the locations to be irradiated or not irradiated with a laser beam are currently set manually by an operator by looking at the overall diagram of the chip. However, manual settings for complex multi-project wafers have problems such as being extremely time consuming and prone to human error.

The present invention has been made in view of such problems, and its purpose is to easily and quickly provide accurate XY coordinate values of the streets to a processing device when processing a wafer partitioned by discontinuous streets. An object of the present invention is to provide a method for manufacturing a chip that can be configured.

In order to solve the above-mentioned problems and achieve the objects, the chip manufacturing method of the present invention includes a plurality of streets in a first direction formed on the surface of a wafer substrate; a plurality of streets in the second direction formed in a second direction perpendicular to the direction, and at least one of the streets in the first direction and the streets in the second direction is formed discontinuously. A method for manufacturing chips, the method comprising manufacturing chips by irradiating a wafer with a laser beam along the streets in the first direction and the streets in the second direction to manufacture chips, the method comprising: a street detection step of detecting a street in the first direction and a street in the second direction based on the image obtained in the imaging step; Contains data on each irradiated or non-irradiated machining feed amount calculated for each of the straight line including the street in the first direction and the straight line including the street in the second direction, and data on each index feed amount . a control map creation step of creating a control map, and irradiating a laser beam along a street in either one of the street in the first direction and the street in the second direction of the wafer based on the control map; and a second laser beam irradiation step of irradiating the wafer with a laser beam along the street in the other direction after the first laser beam irradiation step. Features.

Before the street detection step, a chip formed in an area defined by the street in the first direction and the street in the second direction is detected from the image obtained in the imaging step, and The method may further include a masking step of masking the portion of the chip by image processing.

The first laser beam irradiation step and the second laser beam irradiation step include irradiating the wafer with a laser beam having a wavelength that is transparent to the wafer by positioning a convergence point inside the wafer to form a modified layer. The method may also include a step of forming a modified layer.

The present invention allows a processing device to easily and quickly set accurate XY coordinate values of the streets when processing a wafer partitioned by discontinuous streets.

FIG. 1 is a perspective view of a wafer to be processed in the chip manufacturing method according to the first embodiment. FIG. 2 is a partially enlarged plan view of the wafer shown in FIG. FIG. 3 is a perspective view showing a configuration example of a laser processing device used in the chip manufacturing method according to the first embodiment. FIG. 4 is a flowchart showing the flow of the chip manufacturing method according to the first embodiment. FIG. 5 is a diagram showing an example of an image captured in the imaging step of FIG. 4. FIG. 6 is a diagram showing an example of an image processed in the street detection step of FIG. 4. FIG. 7 is a diagram showing an example of a display screen of the control map created in the control map creation step of FIG. 4. FIG. 8 is a diagram showing an example of a display screen of the control map created in the control map creation step of FIG. 4. FIG. 9 is a perspective view showing an example of the first laser beam irradiation step. FIG. 10 is a perspective view showing an example of the second laser beam irradiation step. FIG. 11 is a flowchart showing the flow of the chip manufacturing method according to the second embodiment. FIG. 12 is a diagram showing one state of an image being processed in the masking step of FIG. 11. FIG. 13 is a diagram showing a state after FIG. 12. FIG. 14 is a cross-sectional view showing an example of the modified layer forming step according to the third embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Modes (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. Further, the constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. Further, various omissions, substitutions, or changes in the configuration can be made without departing from the gist of the present invention.

[First embodiment]
A method for manufacturing the chip 202 according to the first embodiment of the present invention will be described based on the drawings. First, the configuration of the wafer 200 that is the object of processing in the method for manufacturing a chip 202 according to the first embodiment will be described. FIG. 1 is a perspective view of a wafer 200 that is a processing target of the method for manufacturing a chip 202 according to the first embodiment. FIG. 2 is an enlarged plan view of a portion of the wafer 200 in FIG.

In the first embodiment, the wafer 200 to be processed in the method for manufacturing the chip 202 is a wafer such as a disk-shaped semiconductor device wafer or an optical device wafer, which has a wafer substrate 203 made of silicon, sapphire, gallium arsenide, or the like. In the first embodiment, the wafer 200 is a disc-shaped multi-project wafer with a diameter of 8 inches and a thickness of 400 μm. The method for manufacturing the chip 202 according to the first embodiment is a method in which the wafer 200 shown in FIGS. 1 and 2 is divided to form a plurality of chips 202.

As shown in FIGS. 1 and 2, the wafer 200 has a plurality of streets 204 formed on the surface 208 of the wafer substrate 203, and devices 207 defined by the streets 204. The street 204 includes a plurality of first streets 205 extending parallel to a first direction 211 and a plurality of second streets 206 extending parallel to a second direction 212 orthogonal to the first direction 211. . In the wafer 200, at least one of the first streets 205 and the second streets 206 is formed discontinuously. In the first embodiment, both the first street 205 and the second street 206 are formed discontinuously.

The device 207 is, for example, an integrated circuit such as an IC (Integrated Circuit) or an LSI (Large Scale Integration), an image sensor such as a CCD (Charge Coupled Device), or a CMOS (Complementary Metal Oxide Semiconductor), or an MEMS (Micro Electro Mechanical Systems), etc.

In a first embodiment, wafer 200 is divided into individual devices 207 along streets 204 and fabricated into chips 202. Chip 202 includes a portion of wafer substrate 203 and devices 207 on wafer substrate 203 . The planar shape of the chip 202 is square or rectangular.

Next, the configuration of the laser processing apparatus 1 used in the method for manufacturing the chip 202 according to the first embodiment will be described. FIG. 3 is a perspective view showing a configuration example of the laser processing apparatus 1 used in the method for manufacturing the chip 202 according to the first embodiment. In the following description, the X-axis direction is one direction on the horizontal plane. The Y-axis direction is a direction that intersects the X-axis direction in a horizontal plane. The Z-axis direction is a direction that intersects the X-axis direction and the Y-axis direction. In the laser processing apparatus 1 of the first embodiment, the processing feed direction is the X-axis direction, and the indexing feed direction is the Y-axis direction.

The laser processing apparatus 1 according to the first embodiment is an apparatus that processes a wafer 200 as a processing target by irradiating a laser beam 21 along streets 204 to the wafer 200 . The processing of the wafer 200 by the laser processing apparatus 1 includes, for example, a modified layer forming process in which a modified layer is formed inside the wafer 200 by stealth dicing, a groove process in which a groove is formed on the surface 208 of the wafer 200, or a process performed along the streets 204. This includes a cutting process in which the wafer 200 is cut using a wafer. As shown in FIG. 3, the laser processing apparatus 1 includes a chuck table 10, a laser beam irradiation unit 20, a processing feed unit 50, an imaging unit 80, a display unit 90, and a control unit 100.

The wafer 200 processed by the laser processing apparatus 1 is supported by an annular frame 220 and an expandable tape 221 in the first embodiment. The annular frame 220 has an opening larger than the outer diameter of the wafer 200. The expandable tape 221 is attached to the back side of the annular frame 220. The expandable tape 221 includes a base layer made of a synthetic resin with elasticity and an adhesive layer laminated on the base layer and made of a synthetic resin with elasticity and adhesiveness. The wafer 200 is positioned at a predetermined position in the opening of the annular frame 220 and is fixed to the annular frame 220 and the expanding tape 221 by pasting the back surface 209 to the expanding tape 221.

The chuck table 10 holds the wafer 200 with a holding surface 11. The holding surface 11 has a disc shape made of porous ceramic or the like. In the first embodiment, the holding surface 11 is a plane parallel to the horizontal direction. The holding surface 11 is connected to a vacuum suction source, for example via a vacuum suction path. The chuck table 10 holds the wafer 200 placed on the holding surface 11 by suction. A plurality of clamp parts 12 are arranged around the chuck table 10 to clamp an annular frame 220 that supports the wafer 200. The chuck table 10 is rotated by a rotation unit 13 about an axis parallel to the Z-axis direction. The rotation unit 13 is supported by an X-axis direction moving plate 14. The rotation unit 13 and the chuck table 10 are moved in the X-axis direction by the X-axis movement unit 60 of the processing feed unit 50 via the X-axis movement plate 14 . The rotation unit 13 and the chuck table 10 are moved in the Y-axis direction by the Y-axis movement unit 70 of the processing feed unit 50 via the X-axis movement plate 14, the X-axis movement unit 60, and the Y-axis movement plate 15. .

The laser beam irradiation unit 20 is a unit that irradiates the wafer 200 held on the chuck table 10 with a pulsed laser beam 21 . The laser beam irradiation unit 20 includes, for example, a laser beam oscillator, a mirror, and a condenser lens. The laser beam oscillator oscillates a laser beam 21 for processing the wafer 200. The mirror reflects the laser beam 21 oscillated by the laser beam oscillator toward the wafer 200 held on the holding surface 11 of the chuck table 10 . The condenser lens condenses the laser beam 21 reflected by the mirror onto the wafer 200 . The laser beam 21 irradiated by the laser beam irradiation unit 20 may have a wavelength that is transparent to the wafer 200 or may have a wavelength that is absorptive to the wafer 200.

The processing feed unit 50 is a unit that relatively moves the chuck table 10 and the laser beam irradiation unit 20 in the processing feed direction. The processing feed unit 50 includes an X-axis movement unit 60 and a Y-axis movement unit 70. The X-axis moving unit 60 is a processing feed means that moves the chuck table 10 in the X-axis direction. The Y-axis moving unit 70 is an indexing and feeding means that moves the chuck table 10 in the Y-axis direction. The X-axis moving unit 60 and the Y-axis moving unit 70 are installed on the device main body 2 of the laser processing device 1 in the first embodiment. The X-axis movement unit 60 supports the X-axis direction movement plate 14 so as to be movable in the X-axis direction. The Y-axis moving unit 70 supports the Y-axis direction moving plate 15 so as to be movable in the Y-axis direction.

The X-axis moving unit 60 includes a known ball screw 61, a known pulse motor 62, and a known guide rail 63. The ball screw 61 is provided rotatably around its axis. The pulse motor 62 rotates the ball screw 61 around its axis. The guide rail 63 supports the X-axis direction moving plate 14 so as to be movable in the X-axis direction. The guide rail 63 is fixedly provided to the Y-axis direction moving plate 15. The Y-axis moving unit 70 includes a known ball screw 71, a known pulse motor 72, and a known guide rail 73. The ball screw 71 is provided rotatably around its axis. The pulse motor 72 rotates the ball screw 71 around its axis. The guide rail 73 supports the Y-axis direction moving plate 15 so as to be movable in the Y-axis direction. The guide rail 73 is fixedly provided to the device main body 2.

The processing feed unit 50 may further include a Z-axis moving unit that moves the condensing lens included in the laser beam irradiation unit 20 in the Z-axis direction. The Z-axis moving unit is installed, for example, on a pillar 3 that stands up from the apparatus main body 2, and supports the condensing lens of the laser beam irradiation unit 20 so as to be movable in the Z-axis direction.

The imaging unit 80 images the wafer 200 held on the chuck table 10. The imaging unit 80 includes a CCD camera or an infrared camera that images the wafer 200 held on the chuck table 10.

The display unit 90 includes a display surface 91 that displays the status of machining operations, images, and the like. The display unit 90 is a display section configured with a liquid crystal display device or the like. When display surface 91 includes a touch panel, display unit 90 may include an input section. The input unit can accept various operations such as registering processing content information by an operator. The input unit may be an external input device such as a keyboard. In the display unit 90, the information and images displayed on the display surface 91 are switched by an operation from an input section or the like. Display unit 90 may include a notification section. The notification unit notifies the operator of the laser processing device 1 of predetermined notification information by emitting at least one of sound and light. The notification unit may be an external notification device such as a speaker or a light emitting device. Display unit 90 is connected to control unit 100.

The control unit 100 controls each of the above-mentioned components of the laser processing apparatus 1 and causes the laser processing apparatus 1 to perform a processing operation on the wafer 200. The control unit 100 controls the laser beam irradiation unit 20, the processing and feeding unit 50, the imaging unit 80, and the display unit 90. The control unit 100 is a computer that includes an arithmetic processing device as a calculation means, a storage device as a storage means, and an input/output interface device as a communication means. The arithmetic processing device includes, for example, a microprocessor such as a CPU (Central Processing Unit). The storage device includes a memory such as ROM (Read Only Memory) or RAM (Random Access Memory). The arithmetic processing device performs various calculations based on a predetermined program stored in the storage device. The arithmetic processing device outputs various control signals to each of the above-mentioned components via the input/output interface device according to the arithmetic results, thereby controlling the laser processing device 1.

The control unit 100 causes the imaging unit 80 to image the wafer 200. The control unit 100 performs image processing on the image captured by the imaging unit 80. Control unit 100 detects street 204 through image processing. The control unit 100 creates a control map of XY coordinate values for controlling the position where the laser beam 21 is irradiated for each of the first street 205 and the second street 206. The control unit 100 drives the processing feed unit 50 and causes the laser beam irradiation unit 20 to irradiate the laser beam 21 based on the control map.

Next, a method for manufacturing the chip 202 according to the first embodiment will be explained. FIG. 4 is a flowchart showing the flow of the method for manufacturing the chip 202 according to the first embodiment. As shown in FIG. 4, the method for manufacturing the chip 202 includes an imaging step ST11, a street detection step ST13, a control map creation step ST14, a first laser beam irradiation step ST15, and a second laser beam irradiation step ST16. and, including.

FIG. 5 is a diagram showing an example of an image captured in the imaging step ST11 of FIG. 4. The imaging step ST11 is a step of imaging the front surface 208 side of the wafer substrate 203.

Specifically, in the imaging step ST11, first, the back surface 209 of the wafer 200 is held by suction on the holding surface 11 of the chuck table 10 of the laser processing apparatus 1. At this time, the operator operates the rotation unit 13 to align the position so that the first direction 211 in which the first street 205 extends is parallel to the X-axis direction, which is the processing feed direction of the laser processing device 1. do. The alignment may be performed based on the streets 204 detected from the captured image captured by the imaging unit 80.

In imaging step ST11, next, the imaging unit 80 images the front surface 208 of the wafer 200 as shown in FIG. The captured image captured by the imaging unit 80 includes at least the area of the street 204 of the wafer 200 and the area of the device 207 in a distinguishable manner. The control unit 100 acquires a captured image captured by the imaging unit 80. In the first embodiment, the control unit 100 acquires a captured image in an 8-bit bitmap format. The control unit 100 displays the acquired captured image on the display surface 91 of the display unit 90.

FIG. 6 is a diagram showing an example of an image processed in the street detection step ST13 of FIG. 4. The street detection step ST13 is a step of detecting the street 204.

Specifically, in the street detection step ST13, the street 204 is detected based on the captured image obtained in the imaging step ST11. Before the street detection step ST13, for example, in order to detect the area of the street 204 and the device 207, the captured image captured by the imaging unit 80 is converted into a monochrome image. In the first embodiment, the white portion of the converted monochrome image is detected as the street 204 area. Conversion of the captured image into a monochrome image is performed by binarization processing. If the captured image is a color image, the captured image is grayscaled and converted into a grayscale image before the binarization process is performed. In the binarization process, when the value of each pixel in a grayscale image exceeds a predetermined threshold, it is replaced with white, and when the value of each pixel is below a predetermined threshold, it is replaced with black, converting the grayscale image into monochrome. Convert to image. When the captured image is 8 bits with 256 gradations, the predetermined threshold is, for example, 100. As a result, in the captured image, the area of the street 204 is converted to white, and the area of the device 207 is converted to black. In the street detection step ST13, a smoothing filter or noise removal may be performed before performing the binarization process.

In the street detection step ST13, the street 204 may be detected by distinguishing it into a first street 205 extending in the first direction 211 and a second street 206 extending in the second direction 212. The control unit 100 displays the acquired monochrome image on the display surface 91 of the display unit 90. Note that the area of the device 207 that is painted black when converting to a monochrome image is shown in gray in FIG. The control unit 100 may display the captured image obtained in the imaging step ST11 and the monochrome image side by side on the display surface 91 of the display unit 90. Thereby, the operator may visually check whether the area of the street 204 in the captured image matches the area displayed in white in the monochrome image.

In the street detection step ST13, image recognition using artificial intelligence (AI) may be used to detect the street 204. The control unit 100 has learning data for artificial intelligence. The learning model is generated by having artificial intelligence perform machine learning on the street 204. Data of images captured by the imaging unit 80 is accumulated in the learning data. Ordinary image processing and image recognition using artificial intelligence may be used together, and image recognition using artificial intelligence may be used only when the reliability of the results of ordinary image processing is low.

7 and 8 are diagrams showing examples of display screens of the control map created in the control map creation step ST14 of FIG. 4. The control map creation step ST14 is a step of creating a control map of XY coordinate values for each of the first street 205 and the second street 206 after the street detection step ST13.

The first display screen 92 shown in FIG. 7 includes an index feed number display section 921 for the laser beam 21 in the Y-axis direction, which is the index feed direction, an index feed amount display section 922, and an irradiation pattern number display section 923. . The index feed number is a number indicating the order in which the laser beam 21 is irradiated in the Y-axis direction, which is the index feed direction. The indexing feed amount is the feed amount for indexing a straight line including the first street 205 after completion of irradiation in the X-axis direction, which is the machining feed direction. The index feed amount matches the widthwise interval of the first street 205. The irradiation pattern number is a number indicating the type of pattern for switching between irradiation and non-irradiation in the X-axis direction, which is the processing feed direction, for a straight line including the first street 205.

The second display screen 93 shown in FIG. 8 includes an irradiation pattern number display section 931, a processing feed number display section 932 for the laser beam 21 in the X-axis direction which is the processing feed direction, a processing feed amount display section 933, and an irradiation pattern number display section 931. It includes a non-irradiation display section 934 and a total machining feed amount display section 935. The irradiation pattern number is a number indicating the type of pattern for switching between irradiation and non-irradiation in the X-axis direction, which is the processing feed direction, for a straight line including the first street 205. The irradiation pattern number shown in the irradiation pattern number display section 931 of the second display screen 93 corresponds to the irradiation pattern number shown in any of the irradiation pattern number display sections 923 of the first display screen 92. The processing feed number is a number indicating the order in which the laser beam 21 is irradiated or not irradiated in the X-axis direction, which is the processing feed direction. The processing feed amount is the processing feed amount for a straight line including the first street 205 up to the position where irradiation or non-irradiation is switched. The irradiation/non-irradiation display section 934 indicates whether or not the laser beam 21 is irradiated during the processing feed of the corresponding processing feed number. In the irradiation/non-irradiation display section 934, in the first embodiment, black indicates irradiation and white indicates non-irradiation. The total processing feed amount is the total value of processing feed amounts for irradiating or not irradiating the laser beam 21 on a straight line including the first street 205.

In the example shown in FIGS. 7 and 8, for example, index feed number No. 1, at a position in the Y-axis direction with an index feed amount of 2.0 inches, the irradiation pattern number Table. 1 is executed. Irradiation pattern number Table. 1, processing feed number No. 1 to No. 12 in order. For example, processing feed number No. 1 indicates that the laser beam 21 is not irradiated from the initial position to the processing feed amount of 2.0 inches. For example, processing feed number No. 2, processing feed number No. This shows that the laser beam 21 is irradiated from the position where step 1 ends to the processing feed amount of 0.5 inch. In this case, the first street 205 is not formed in the range from the initial position to 2.0 inches in the Y-axis direction and from the initial position to 2.0 inches in the X-axis direction; It is shown that the first street 205 is formed in the range up to .5 inch.

In the control map creation step ST14, first, a control map is set that indicates areas to be irradiated with the laser beam 21 and areas not to be irradiated when processing the first street 205. Specifically, each index feed amount 922 is calculated from the coordinates of each first street 205 in the Y-axis direction. In the control map creation step ST14, next, the laser beam 21 is irradiated with respect to the straight line including each first street 205, with the boundary between the area of the street 204 and the area of the device 207 as the irradiation switching position of the laser beam 21. Alternatively, each processing feed amount 933 for non-irradiation is calculated. Regarding the straight line including each first street 205, if the irradiation switching positions coincide with each other, the irradiation patterns are stored as the same irradiation pattern. For example, in the example shown in FIG. 7, the index feed number is No. In the processing of Nos. 1, 3, 8, and 10, the irradiation pattern number Table. Processed using one irradiation pattern.

In the control map creation step ST14, a control map for machining the first street 205 is created, and then a control map for machining the second street 206 is created. When processing the second street 206, alignment is made so that the second direction 212 in which the second street 206 extends is parallel to the X-axis direction, which is the processing feed direction of the laser processing device 1 (Fig. 10). Therefore, the control map for machining the second street 206 is created in the same way as the control map for machining the first street 205.

What is the data of each irradiated or non-irradiated machining feed amount 933 calculated for the straight line including the first street 205 and the straight line including the second street 206, and the data of each index feed amount 922? , for example, is output as CSV data. The operator may display the CSV data using a macro on a dedicated EXCEL (registered trademark) sheet of a personal computer, for example. This allows you to fine-tune each value. After making fine adjustments to each value, the operator imports the control map into the control unit 100 of the laser processing apparatus 1 using, for example, a USB flash drive. The control unit 100 may display each calculated data on the display surface 91 of the display unit 90. The method for creating the control map is not limited to the above method, and may be entirely executed by the control unit 100.

FIG. 9 is a perspective view showing an example of the first laser beam irradiation step ST15. The first laser beam irradiation step ST15 is a step of irradiating the laser beam 21 along the first street 205 based on the control map.

Specifically, in the first laser beam irradiation step ST15, as shown in FIG. Irradiate along street 205. At this time, the control unit 100 relatively moves the chuck table 10 and the laser beam irradiation unit 20 while switching between irradiation and non-irradiation of the laser beam 21 based on the control map. In the example shown in FIGS. 7 and 8, the control unit 100 first selects the index feed number No. Execute 1. Index feed number No. 1, the control unit 100 moves the laser beam irradiation unit 20 by 2.0 inches from the initial position in the Y-axis direction, which is the indexing direction. The control unit 100 controls the irradiation pattern number Table. Execute 1. Irradiation pattern number Table. 1, as shown in the control map of FIG. 8, the control unit 100 controls the machining feed number No. 1 to No. 12 in order. For example, the control unit 100 controls processing feed number No. 1, the irradiation of the laser beam 21 is stopped while the processing is fed by 2.0 inches. The control unit 100 controls the processing feed number No. In step 2, the laser beam 21 is irradiated while processing is carried out by 0.5 inch. Similarly, the control unit 100 controls the processing feed number No. 3 to no. When it is executed up to 12, the index feed number No. 12 is executed. Execute 2. In the first laser beam irradiation step ST15, when all the first streets 205 are irradiated, the process moves to the second laser beam irradiation step ST16.

FIG. 10 is a perspective view showing an example of the second laser beam irradiation step ST16. The second laser beam irradiation step ST16 is a step of irradiating the laser beam 21 along the second street 206 after the first laser beam irradiation step ST15.

Specifically, in the second laser beam irradiation step ST16, first, as shown in FIG. 10, the second direction 212 in which the second street 206 extends is the The rotation unit 13 (see FIG. 1) is operated to align the position parallel to the direction. In the second laser beam irradiation step ST16, next, the laser beam irradiation unit 20 irradiates the laser beam 21 along the second street 206 from the front surface 208 side of the wafer 200 held on the chuck table 10. At this time, the control unit 100 relatively moves the chuck table 10 and the laser beam irradiation unit 20 while switching between irradiation and non-irradiation of the laser beam 21 based on the control map. When all the second streets 206 are irradiated, the second laser beam irradiation step ST16 is ended.

As described above, in the method for manufacturing the chip 202 according to the first embodiment, based on the streets 204 detected from the captured image of the wafer 200, the laser A control map for controlling the position where the beam 21 is irradiated is created. The method for manufacturing the chip 202 irradiates the laser beam 21 along the first street 205 based on the control map. In the method for manufacturing the chip 202, after the first street 205 has been completely irradiated with the laser beam 21, the laser beam 21 is irradiated along the second street 206 based on the control map.

This makes it possible to omit manual input of the XY coordinate values of the locations to be irradiated or not irradiated with the laser beam 21, thereby reducing the number of steps required by the operator. Furthermore, since the accurate position of the street 204 can be stored in the control unit 100 of the laser processing apparatus 1, human errors can be suppressed. Therefore, the method for manufacturing the chip 202 allows the laser processing apparatus 1 to easily and quickly set accurate XY coordinate values of the streets 204 when processing the wafer 200 partitioned by the discontinuous streets 204.

[Second embodiment]
A method for manufacturing a chip 202 according to a second embodiment of the present invention will be described. FIG. 11 is a flowchart showing the flow of the method for manufacturing the chip 202 according to the second embodiment. The method for manufacturing the chip 202 according to the second embodiment differs from the method for manufacturing the chip 202 according to the first embodiment in that it includes a masking step ST12 before the street detection step ST13. In the second embodiment, the wafer 200 is one in which the streets 204 do not have a pattern such as TEG (Test Element Group).

FIG. 12 is a diagram showing one state of the image being processed in the masking step ST12 of FIG. 11. FIG. 13 is a diagram showing a state after FIG. 12. Masking step ST12 is a step of masking the chip 202 (device 207) portion of the image obtained in imaging step ST11 by image processing.

Specifically, in the masking step ST12, image processing is performed on the captured image obtained in the imaging step ST11. When the captured image is a color image, the captured image is converted into a gray scale image. In the masking step ST12, for example, binarization processing is performed for each pixel from the lower left to the upper right of the captured image. In the binarization process, when the value of each pixel in a grayscale image exceeds a predetermined threshold, it is replaced with white, and when the value of each pixel is below a predetermined threshold, it is replaced with black, converting the grayscale image into monochrome. Convert to image. When the captured image is 8 bits with 256 gradations, the predetermined threshold is, for example, 100. Note that the masking area 213 that is filled in black when converting to a monochrome image is illustrated in gray in FIGS. 12 and 13.

In masking step ST12, pixels surrounded on two sides by black pixels are further replaced with black. In the second embodiment, since the binarization process is executed from the lower left to the upper right, pixels on the left side and pixels on the lower side that are black are replaced with black. In the example shown in FIG. 12, the pixel 214 is replaced with black because the pixels on the left side and the pixels on the bottom side are black. In the example shown in FIG. 13, the pixel 214 on the left side is black, but the pixel on the bottom side is white, so it is replaced with white. The outer periphery of the chip 202 (device 207) is replaced with black because the pixel values continuously fall below a predetermined threshold due to the guard ring 215 surrounding the device 207. Therefore, by replacing a pixel surrounded by black pixels on two sides with black, the entire area surrounded by the guard ring 215 can be replaced with black, so the entire portion of the chip 202 (device 207) can be masked. can do.

[Third embodiment]
A method for manufacturing a chip 202 according to a third embodiment of the present invention will be described. The method for manufacturing a chip 202 according to the third embodiment is different from the method for manufacturing a chip 202 according to the first embodiment in that the first laser beam irradiation step ST15 and the second laser beam irradiation step ST16 are modified. The difference is that it includes a layer formation step.

FIG. 14 is a cross-sectional view showing an example of the modified layer forming step according to the third embodiment. The modified layer forming step is a step of forming a modified layer 216 on the wafer 200 to serve as a starting point for division.

Modified layer 216 refers to a region that has a density, refractive index, mechanical strength, or other physical property that is different from that of its surroundings. The modified layer 216 includes, for example, a melt-treated region, a crack region, a dielectric breakdown region, a refractive index change region, and a region in which these regions are mixed. The modified layer 216 has lower mechanical strength and the like than other parts of the wafer 200.

In the modified layer forming step, a pulsed laser beam 21 having a wavelength that is transparent to the wafer 200 is irradiated from the front surface 208 side of the wafer 200 with a focal point 22 positioned inside the wafer 200 . Since the laser beam irradiation unit 20 irradiates the wafer 200 with a laser beam 21 having a transmittable wavelength, a modified layer 216 is formed inside the wafer substrate 203 along the streets 204 .

In the modified layer forming step, the laser beam irradiation unit 20 changes the position of the focal point 22 of the laser beam 21 in the thickness direction in each pass, and forms the modified layer 216 on the streets 204 in the thickness direction of the wafer substrate 203. Form multiple. In the modified layer forming step, for example, the laser beam irradiation unit 20 irradiates the wafer 200 with three passes of the laser beam 21, thereby forming three modified layers 216 in the thickness direction of the wafer substrate 203. do. The number of modified layers 216 formed in the thickness direction of the wafer substrate 203 is not limited to three.

Note that the present invention is not limited to the above embodiments. That is, various modifications can be made without departing from the gist of the invention.

1 Laser processing device 10 Chuck table 11 Holding surface 13 Rotation unit 20 Laser beam irradiation unit 21 Laser beam 22 Focus point 50 Processing feed unit 80 Imaging unit 90 Display unit 100 Control unit 200 Wafer 202 Chip 203 Wafer substrate 204 Street 205 First street 206 second street 207 device 208 front side 209 back side 211 first direction 212 second direction

Claims (3)

A plurality of streets in a first direction formed in a first direction on a surface of a wafer substrate, and a plurality of streets in a second direction formed in a second direction perpendicular to the first direction. ,
For a wafer in which at least one of the streets in the first direction and the streets in the second direction is formed discontinuously, along the streets in the first direction and the streets in the second direction. A method of manufacturing a chip by irradiating it with a laser beam and dividing it into chips, the method comprising:
an imaging step of imaging the front side of the wafer substrate;
a street detection step of detecting a street in the first direction and a street in the second direction based on the image obtained in the imaging step;
After the street detection step, data of each machining feed amount of irradiation or non-irradiation calculated for each of the straight line including the street in the first direction and the straight line including the street in the second direction; a control map creation step of creating a control map including data of each indexed feed amount ;
a first laser beam irradiation step of irradiating a laser beam along a street in one of the first direction street and the second direction street of the wafer based on the control map;
After the first laser beam irradiation step, a second laser beam irradiation step of irradiating the wafer with a laser beam along the street in the other direction;
A method for manufacturing a chip, comprising: Before the street detection step, a chip formed in an area defined by the street in the first direction and the street in the second direction is detected from the image obtained in the imaging step, and The method further includes a masking step of masking a portion of the chip by image processing.
A method for manufacturing a chip according to claim 1. The first laser beam irradiation step and the second laser beam irradiation step include irradiating the wafer with a laser beam having a wavelength that is transparent to the wafer by positioning a convergence point inside the wafer to form a modified layer. characterized by comprising a step of forming a modified layer,
A method for manufacturing a chip according to claim 1 or 2.

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