JP5789802B2 - Manufacturing method of semiconductor chip - Google Patents

Description

  The present invention relates to a method for manufacturing a semiconductor chip by dividing a semiconductor wafer into small pieces.

  In recent years, stealth dicing has attracted attention as one of dicing techniques. In the stealth dicing method, first, a modified region is formed by condensing a laser beam inside a semiconductor wafer such as silicon to which a dicing tape is attached. By stretching the dicing tape, the semiconductor wafer is divided into small pieces starting from the modified region.

  In addition, a method of separating a sapphire substrate having a nitride-based semiconductor element formed on the surface using laser light is known. In this method, the separation groove is formed on the surface on which the nitride semiconductor element is formed. A laser beam is scanned along the separation groove to form an altered portion.

  A technique is known in which a groove is formed on a back surface of a semiconductor wafer along a dividing line, and a laser beam is irradiated into the groove to form a modified layer. In this method, after the semiconductor wafer is separated into small pieces, back surface grinding is performed to remove the back surface layer portion to the depth of the groove. Thereby, a semiconductor chip having a high-quality side surface can be obtained.

  A technique is known in which a recess is formed on an element forming surface of a semiconductor wafer, and the semiconductor wafer is separated by irradiating the bottom surface of the recess with laser light. In this method, debris can be prevented from adhering to the element formation surface by adjusting the depth and width of the recess.

JP 2004-79746 A JP 2006-245062 A JP 2007-134454 A JP 2008-166445 A

  When laser irradiation is performed from the back surface of a semiconductor wafer such as silicon, the position of the planned separation line (street) of the wafer must be detected. A surface protection tape is affixed to the surface where the elements are formed, and the semiconductor wafer is held on the stage with the surface facing downward. The position of the street is detected by observing the pattern formed on the front surface of the semiconductor wafer from the back surface of the semiconductor wafer using infrared light that passes through the semiconductor wafer.

  The amount of infrared absorption varies depending on the thickness of the semiconductor wafer, the amount of impurities doped, and the like. When the amount of absorbed infrared rays increases, it becomes difficult to recognize the pattern formed on the surface.

According to one aspect of the present invention, a groove is formed along the street on the surface of a semiconductor wafer in which a plurality of chip regions on which semiconductor elements are formed and a street is defined between the chip regions. And a step of detecting the position of the groove through the semiconductor wafer from the back surface of the semiconductor wafer, and by causing a laser beam to enter the semiconductor wafer from the back surface based on the position where the groove is detected. A step of modifying the semiconductor wafer at a position corresponding to the groove to form a modified region, and a step of separating the semiconductor wafer into small pieces at the position of the groove and the modified region, in the step of forming the modified region, the one of the laser beam incident on a semiconductor wafer, a semiconductor observing the power of the laser beam transmitted through the semiconductor wafer Tsu method of producing flops are provided.

According to another aspect of the present invention, a plurality of chip regions having semiconductor elements formed on the surface, and fixing a semiconductor wafer having streets defined between the chip regions to a transparent chuck table; The surface of the semiconductor wafer is observed from the surface side while being fixed to the chuck table, and the position of the street is detected. Based on the detection result of the street position, the surface is fixed to the chuck table. In this state, a laser beam is incident on the semiconductor wafer from the back surface and scanned along the streets to modify the semiconductor wafer to form a modified region; and in position, and a step of separating into pieces of the semiconductor wafer, in the step of forming the modified region, the laser incident on the semiconductor wafer Of the beam, a method of manufacturing a semiconductor chip to observe the power of the laser beam transmitted through the semiconductor wafer is provided.

  By forming a groove in the semiconductor wafer, the street position can be easily detected. Further, the position of the street can be easily detected by observing the surface of the semiconductor wafer from the surface side.

(1A) and (1B) are a plan view and a cross-sectional view of a semiconductor wafer to be divided in Example 1, respectively. (2A) is a cross-sectional view of a semiconductor wafer and a grinding apparatus at the time of grinding in the semiconductor chip manufacturing method according to the first embodiment, and (2B) and (2C) are cross-sectional views in a state where the semiconductor wafer is installed in a dicing apparatus. It is. (3A) is a cross-sectional view of the semiconductor wafer and the dicing apparatus during dicing in the semiconductor chip manufacturing method according to the first embodiment, and (3B) is a cross-sectional view of the semiconductor wafer after dicing. It is the schematic of a semiconductor wafer and a laser dicing apparatus at the time of the street position detection of the manufacturing method of the semiconductor chip by Example 1. It is the schematic of the semiconductor wafer and laser dicing apparatus in the laser dicing of the manufacturing method of the semiconductor chip by Example 1. FIG. (6A) is a cross-sectional view of the semiconductor wafer after completion of laser dicing, (6B) is a cross-sectional view of the semiconductor wafer during expansion, and (6C) is a cross-sectional view of the semiconductor wafer during ultraviolet irradiation. . (7A) and (7B) are schematic views of the semiconductor chip and the pickup device during the pickup of the semiconductor chip. It is the schematic of the semiconductor wafer at the time of the street position detection of the manufacturing method of the semiconductor chip by Example 2, and a laser dicing apparatus. It is the schematic of the semiconductor wafer and laser dicing apparatus in the laser dicing of the manufacturing method of the semiconductor chip by Example 2. It is the schematic of the semiconductor wafer at the time of the crack observation of the manufacturing method of the semiconductor chip by Example 2, and a laser dicing apparatus. It is the schematic of the semiconductor wafer at the time of street position detection of the manufacturing method of the semiconductor chip by Example 3, and a laser dicing apparatus. It is the schematic of the semiconductor wafer and laser dicing apparatus in the laser dicing of the manufacturing method of the semiconductor chip by Example 3. (13A) and (13B) are cross-sectional views of the semiconductor wafer after completion of laser dicing, and (13C) is a cross-sectional view of the semiconductor wafer during expansion. It is the schematic of the semiconductor wafer at the time of street position detection of the manufacturing method of the semiconductor chip by Example 4, and a laser dicing apparatus. It is the schematic of the semiconductor wafer and laser dicing apparatus in the laser dicing of the manufacturing method of the semiconductor chip by Example 4.

  Examples 1 to 4 will be described with reference to the drawings.

[Example 1]
FIG. 1A shows a plan view of a semiconductor wafer before being separated into semiconductor chips. A plurality of element formation regions (chip regions) 21 arranged in a matrix are defined on the element formation surface (front surface) of the semiconductor wafer 20. A circuit pattern including a semiconductor element or the like is formed in the chip region 21. A street 22 that is a planned separation line is defined between the chip regions 21.

  FIG. 1B is a cross-sectional view taken along one-dot chain line 1B-1B in FIG. 1A. A circuit pattern including semiconductor elements and the like is formed in the chip region 21 defined on the surface 24 of the semiconductor wafer 20. A street 22 is defined between the chip regions 21. A surface opposite to the front surface 24 of the semiconductor wafer 20, that is, a surface on which no circuit pattern is formed is referred to as a back surface 25.

  As an example, the semiconductor wafer 20 has a diameter of 300 mm and a thickness of 780 μm. A case where the thickness of the semiconductor chip separated from the semiconductor wafer 20 is 500 μm will be described.

  As shown in FIG. 2A, a surface protection tape 30 is attached to the surface 24 of the semiconductor wafer 20. The semiconductor wafer 20 is attracted and fixed onto the grinding table 31 with the back surface 25 facing upward. The semiconductor wafer 20 is ground by the back grind wheel 32 until its thickness reaches 500 μm.

  As shown in FIG. 2B, the dicing tape 35 is placed on the dicing table 37. The dicing tape 35 is supported by the wafer frame 36 at the outer peripheral portion thereof. The back surface 25 of the ground semiconductor wafer 20 is attached to the dicing tape 35. The dicing tape 35 is formed of a material that transmits near infrared light. Although the kind of adhesive of the dicing tape 35 is not particularly limited, in this embodiment, a case where an ultraviolet curable resin is used will be described. As shown in FIG. 2C, the surface protection tape 30 is peeled from the semiconductor wafer 20.

  As shown in FIG. 3A, a groove 39 along the street 22 is formed on the surface 24 side of the semiconductor wafer 20 using a blade 38. The depth of the groove 39 is, for example, 400 μm. The thickness from the bottom of the groove 39 to the back surface 25 is 100 μm. As shown in FIG. 3B, grooves 39 are formed along all the streets 22.

  As shown in FIG. 4, the semiconductor wafer 20 is fixed to the chuck table 40 of the laser dicing apparatus with its surface 24 facing downward. In this embodiment, the semiconductor wafer 20 is directly placed on the chuck table 40. However, when there is a concern about damage of the semiconductor wafer 20 due to contact, a porous sheet is placed on the chuck table 40, The semiconductor wafer 20 may be placed thereon. The chuck table 40 is made of a material that reflects near infrared light, for example, a metal such as stainless steel.

  Hereinafter, the laser dicing apparatus used in Example 1 will be described. The laser dicing apparatus includes an observation light source 45, a laser light source 46, a camera 47, and a control device 50. The observation light source 45 emits near-infrared light in a wavelength region that passes through the semiconductor wafer 20. For the observation light source 45, for example, a halogen lamp is used. The laser light source 46 emits an infrared pulse laser beam in a wavelength range that can modify the semiconductor wafer 20 by focusing the light within the semiconductor wafer 20. Specifically, the wavelength of the infrared pulse laser beam is a wavelength region that transmits the semiconductor wafer 20, but has a power that causes multiphoton absorption at the focal position. As the laser light source 46, for example, an Nd: YAG laser that emits an infrared laser beam having a wavelength of 1064 nm is used.

  Part of the near-infrared light emitted from the observation light source 45 is reflected by the beam splitter 49, passes through the dichroic mirror 48, and enters the dicing tape 35. Further, the light passes through the dicing tape 35 and enters the semiconductor wafer 20. Near infrared light partially absorbed by the semiconductor wafer 20 and reflected by the chuck table 40 passes through the dichroic mirror 48, and part passes through the beam splitter 49 and enters the camera 47. The camera 47 has sensitivity in the wavelength range of near-infrared light emitted from the observation light source 45.

  The infrared laser beam emitted from the laser light source 46 is reflected by the dichroic mirror 48 and is condensed inside the semiconductor wafer 20. The control device 50 controls the observation light source 45 and the laser light source 46 and receives an image signal captured by the camera 47.

  After fixing the semiconductor wafer 20 with the dicing tape 35 affixed to the chuck table 40, near-infrared light is emitted from the observation light source 45, reflected by the chuck table 40 through the semiconductor wafer 20 by the camera 47. Is received. The control device 50 detects the position of the groove 39 by analyzing the image signal received from the camera 47. When the position of the groove 39 is detected, θ correction of the chuck table 40 is performed and a position to be scanned with the laser beam is determined.

As shown in FIG. 5, an infrared laser beam is emitted from a laser light source 46. The focal point of the laser beam is adjusted so as to be positioned between the bottom surface of the groove 39 and the back surface 25 of the semiconductor wafer 20. The laser beam is scanned along the street 22 (groove 39) by moving the chuck table 40 in the in-plane direction. The power density at the focal position of the laser beam is preferably 1 × 10 ⁸ W / cm ² or more. The pulse width of the laser beam is preferably 1 μs or less. The semiconductor wafer 20 at the focal position of the laser beam is modified, and a modified region 26 is formed.

  As shown in FIG. 6A, the modified region 26 is formed along all the streets 22. In the state where the semiconductor wafer 20 is fixed to the chuck table 40, as shown in FIG. 4, the cracks generated in the semiconductor wafer 20 with the formation of the modified region 26 are observed using the camera 47. May be. Whether or not the laser beam needs to be re-irradiated can be determined based on the shape and size of the crack.

  As shown in FIG. 6B, the dicing tape 35 is stretched radially using a wafer expanding stage 55, thereby applying a tensile force in the in-plane direction to the semiconductor wafer 20. Thus, the semiconductor wafer 20 is divided into small semiconductor chips 20A starting from the modified region 26.

  As shown in FIG. 6C, after the semiconductor chip 20 is divided, the dicing tape 35 is irradiated with ultraviolet rays 56. The adhesive strength of the dicing tape 35 is reduced by the ultraviolet irradiation.

  As shown in FIG. 7A, the dicing tape 35 and the semiconductor wafer 20 are placed on a pickup device. The semiconductor chip 20 </ b> A is pushed up by the push-up pin 56. The collet 57 is moved above the pushed up semiconductor chip 20A. As shown in FIG. 7B, the pushed-up semiconductor chip 20A is picked up by the collet 57 and picked up.

  In the first embodiment, the groove 39 is observed with the camera 47 in the step shown in FIG. Compared with the case where the circuit pattern formed on the surface 24 of the semiconductor wafer 20 is observed, image information with high contrast can be obtained. For this reason, the position of the street 22 can be easily detected. In order to facilitate the detection of the groove 39, the depth of the groove 39 is preferably set to ¼ or more of the thickness of the semiconductor wafer 20. As an example, the thickness is preferably 50 μm or more.

  On the other hand, if the groove 39 is too deep, chips and cracks are likely to occur during dicing using a blade. Furthermore, the region where the modified region can be formed by the laser beam becomes narrow (thin), making it difficult to control the processing position. Therefore, the depth of the groove 39 is preferably 4/5 or less of the thickness of the semiconductor wafer 20. As an example, the thickness is preferably 100 μm or less.

[Example 2]
Example 2 will be described with reference to FIGS. The process until the groove 39 shown in FIG. 3B of the first embodiment is formed is the same as the manufacturing method of the second embodiment.

  As shown in FIG. 8, the semiconductor wafer 20 to which the dicing tape 35 is attached is fixed to the chuck table 40 of the laser dicing apparatus with its surface 24 facing downward. A porous sheet may be sandwiched between the chuck table 40 and the semiconductor wafer 20. Hereinafter, the laser dicing apparatus used in Example 2 will be described. In addition, description is abbreviate | omitted about the structure same as the laser dicing apparatus used in Example 1. FIG.

  The chuck table 40 is made of a material that transmits near infrared light and visible light. For the chuck table 40, for example, transparent acrylic, glass or the like can be used. The infrared laser beam emitted from the laser light source 46 is reflected by the dichroic mirror 48, passes through the dicing tape 35, and enters the semiconductor wafer 20. The infrared laser beam that has passed through the semiconductor wafer 20 passes through the chuck table 40, is reflected by the dichroic mirror 60, and enters the power meter 61.

  An observation light source 45 disposed below the chuck table 40 emits near-infrared light and visible light. Part of the emitted near-infrared light is reflected by the beam splitter 49, passes through the dichroic mirror 60, the chuck table 40, the semiconductor wafer 20, the dicing tape 35, the dichroic mirror 48, and the beam splitter 65 to be infrared and visible. It enters the camera 47 having sensitivity in the region.

  Part of the visible light emitted from the observation light source 45 is reflected by the beam splitter 49, passes through the dichroic mirror 60 and the chuck table 40, and enters the semiconductor wafer 20. Visible light reflected by the surface 24 of the semiconductor wafer 20 passes through the dichroic mirror 60, and part of visible light passes through the beam splitter 49 and enters the camera 67. The camera 67 has sensitivity in the visible range.

  An observation light source 66 disposed above the chuck table 40 emits visible light. Part of the emitted visible light is reflected by the beam splitter 65, passes through the dichroic mirror 48 and the dicing tape 35, and enters the semiconductor wafer 20. Visible light reflected by the back surface 25 of the semiconductor wafer 20 passes through the dichroic mirror 48, and part of visible light passes through the beam splitter 65 and enters the camera 47.

  As described above, the camera 47 disposed above the chuck table 40 receives both near-infrared light transmitted through the semiconductor wafer 20 and visible light reflected from the back surface 25 of the semiconductor wafer 20. A camera 67 disposed below the chuck table 40 receives visible light reflected by the surface 24 of the semiconductor wafer 20.

  The control device 50 controls the observation light sources 45 and 66 and the laser light source 46. The laser power measured by the power meter 61 and the image signal generated by the cameras 47 and 67 are input to the control device 50.

  In a state where the semiconductor wafer 20 to which the dicing tape 35 is attached is fixed to the chuck table 40, near-infrared light and visible light are emitted from the observation light source 45 and the near-infrared light transmitted through the semiconductor wafer 20 is transmitted to the camera 47. Observe at. The observation result is input to the control device 50 as an image signal. The control device 50 detects the position of the groove 39 by analyzing the image signal. Based on the detection result, θ correction of the chuck table 40 is performed.

  As shown in FIG. 9, an infrared laser beam is emitted from the laser light source 46 and condensed in the semiconductor wafer 20. The focal point of the infrared laser beam is located between the bottom surface of the groove 39 and the back surface 25. A modified region 26 is formed at a position where the infrared laser beam is focused. A part of the infrared laser beam is condensed and becomes a divergent beam, passes through the semiconductor wafer 20 and the chuck table 40, is reflected by the dichroic mirror 60, and enters the power meter 61. The laser power measured by the power meter 61 is input to the control device 50.

  The modified region 26 is formed along the groove 39 by moving the chuck table 40 in the in-plane direction.

  As shown in FIG. 10, visible light is emitted from observation light sources 45 and 66, and reflected light from the front surface 24 and the back surface 25 of the semiconductor wafer 20 is observed by cameras 67 and 47, respectively. As a result, it is possible to detect a crack that reaches from the modified region 26 to the bottom surface of the back surface 25 or the groove 39. Whether the laser dicing is good or bad can be determined based on the shape and size of the crack. The determination accuracy can be improved as compared with the case of observing a crack generated inside using near infrared light. When the formation of the modified region 26 is insufficient, the yield can be increased by performing re-irradiation with an infrared laser beam. In addition, you may observe a crack using the cameras 47 and 67 during the laser processing shown in FIG.

  The subsequent steps are the same as the steps shown in FIGS. 6A to 7B of the first embodiment.

  Also in the second embodiment, the position of the groove 39 can be easily detected by observing the transmitted light in the near infrared region shown in FIG.

  Furthermore, in Example 2, the power of the infrared ray beam transmitted through the semiconductor wafer 20 can be measured in the step shown in FIG. By measuring the power of the transmitted light, it is possible to evaluate the thermal effect on the semiconductor elements and the like formed on the semiconductor wafer 20. Hereinafter, a method for evaluating the thermal effect will be described.

  A semiconductor wafer on which no circuit pattern is formed is fixed to the chuck table 40, and an infrared laser beam is emitted under the same conditions as stealth dicing. The measurement result of the laser power by the power meter 61 at this time is stored as a reference power.

  When the modified region 26 is formed on the semiconductor wafer 20 on which the circuit pattern is formed, the laser power measured by the power meter 61 is compared with the reference power. The difference between the two is considered to correspond to the laser power absorbed by the circuit pattern. Therefore, the laser energy absorbed by the circuit pattern can be estimated. Based on the laser energy absorbed by the circuit pattern, it is possible to evaluate the thermal effect on the circuit pattern.

  In addition, during laser processing, it is possible to adjust processing conditions such as laser power in real time based on the measurement result of the power meter 61.

[Example 3]
Example 3 will be described with reference to FIGS. 11 to 13C. The process until the semiconductor wafer 20 shown in FIG. 2A of Example 1 is ground is the same as the manufacturing method of Example 3.

  As shown in FIG. 11, the semiconductor wafer 20 to which the surface protection tape 30 is attached is fixed to the chuck table 40 of the laser dicing apparatus with the surface 24 facing downward. A groove corresponding to the groove 39 of the first embodiment is not formed in the semiconductor wafer 20.

  The configurations of the control device 50, the laser light source 46, the power meter 61, the dichroic mirrors 48 and 60, the observation light source 45, the beam splitter 49, and the camera 67 are the same as those of the laser dicing device of the second embodiment shown in FIG. It is.

  Visible light is emitted from the observation light source 45 while the semiconductor wafer 20 with the surface protection tape 30 attached thereto is fixed to the chuck table 40, and the circuit pattern on the surface 24 of the semiconductor wafer 20 is observed by the camera 67. The observed image signal is input to the control device 50. By analyzing this image signal, the position of the street 22 defined on the surface 24 of the semiconductor wafer 20 is detected.

  As shown in FIG. 12, an infrared ray beam is emitted from a laser light source 46 to form a modified region 26 in a region corresponding to the street 22 of the semiconductor wafer 20. The method for forming the modified region 26 is the same as the method according to the second embodiment shown in FIG. However, in Example 3, since the groove 39 (FIG. 9) is not formed, the infrared laser beam is condensed between the front surface 24 and the back surface 25 of the semiconductor wafer 20.

  After the modified region 26 is formed, the surface 24 of the semiconductor wafer 20 may be observed with a camera 67 as shown in FIG. The shape and size of the crack that has occurred from the modified region 26 and reached the surface 25 can be observed. Note that, as shown in FIG. 8, cracks generated in the semiconductor wafer 20 may be observed using near infrared light that passes through the semiconductor wafer 20. Furthermore, as shown in FIG. 10, the crack reaching the back surface 25 of the semiconductor wafer 20 may be observed using the observation light source 66 and the camera 47 arranged above the chuck table 40.

  By observing the shape and size of the crack reaching the front surface 24 and the back surface 25 of the semiconductor wafer 20, it is possible to improve the accuracy of determining the quality of laser dicing.

  As shown in FIG. 13A, the back surface 25 of the semiconductor wafer 20 on which the modified region 26 is formed and the dicing tape 35 are attached. As shown in FIG. 13B, the surface protection tape 30 is peeled from the semiconductor wafer 20. As shown in FIG. 13C, the dicing tape 35 is radially expanded to divide the semiconductor wafer 20 into small semiconductor chips 20A starting from the modified region 26. The subsequent steps are the same as those shown in FIGS. 6C to 7B.

  In the third embodiment, unlike the first and second embodiments, no groove is formed in the semiconductor wafer 20. In the step shown in FIG. 11, the position of the street 22 can be easily detected by observing the surface 24 of the semiconductor wafer 20 from the surface 24 side using visible light.

[Example 4]
Example 4 will be described with reference to FIGS. 14 and 15. Hereinafter, description will be made by paying attention to differences from the third embodiment, and description of the same configuration will be omitted. In Example 3, as shown in FIG. 11, the semiconductor wafer 20 was fixed to the chuck table 40 via the surface protective tape 30 with the surface 24 facing downward.

  As shown in FIG. 14, in Example 4, the semiconductor wafer 20 is fixed to the chuck table 40 with the back surface 25 of the semiconductor wafer 20 facing downward. For this reason, the surface 24 of the semiconductor wafer 20 faces upward. Correspondingly, the circuit pattern formed on the surface 24 of the semiconductor wafer 20 is observed using the observation light source 60 and the camera 47 disposed above the chuck table 40. The surface protection tape 30 is transparent in the visible light wavelength region. An image signal obtained by the camera 47 is input to the control device 50. By analyzing the image signal, the position of the street 22 can be easily detected.

  As shown in FIG. 15, in Example 4, the infrared laser beam emitted from the laser light source 46 passes through the chuck table 40 from below the chuck table 40 and enters the semiconductor wafer 20. Thereby, the modified region 26 is formed. The infrared laser beam that has passed through the semiconductor wafer 20 and the surface protection tape 30 is reflected by the dichroic mirror 60 and enters the power meter 61. A measured value of the laser power measured by the power meter 61 is input to the control device 50.

  The process after the modified region 26 is formed is the same as the process shown in FIGS. 13A to 13C of the third embodiment.

  Also in the fourth embodiment, as shown in FIG. 14, the circuit pattern formed on the surface 24 of the semiconductor wafer 20 is observed from the surface 24 side using visible light, so that the position of the street 22 is easily detected. can do.

  After forming the modified region 26, as shown in FIG. 14, a crack reaching the surface 24 of the semiconductor wafer 20 may be observed using the observation light source 60 and the camera 47. Furthermore, as shown in FIG. 11, a crack reaching the back surface 25 of the semiconductor wafer 20 may be observed using an observation light source 45 and a camera 67 arranged below the chuck table 40. As in the case of the third embodiment, it is possible to improve the accuracy of determining the quality of laser dicing.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

20 Semiconductor wafer 21 Chip region 22 Street 24 Front surface 25 Back surface 26 Modified region 30 Surface protective tape 31 Grinding table 32 Back grind wheel 35 Dicing tape 36 Wafer frame 37 Dicing table 38 Blade 39 Groove 40 Chuck table 45 Observation light source 46 Laser light source 47 Infrared camera 48 Dichroic mirror 49 Beam splitter 50 Control device 55 Wafer expanding stage 56 Ultraviolet ray 60 Dichroic mirror 61 Power meter 65 Beam splitter 66 Observation light source 67 Camera

Claims (4)

Forming a groove along the street on the surface of the semiconductor wafer in which a plurality of chip regions having semiconductor elements formed on the surface and streets defined between the chip regions;
Detecting the position of the groove through the semiconductor wafer from the back surface of the semiconductor wafer;
Forming a modified region by modifying the semiconductor wafer at a position corresponding to the groove by causing a laser beam to enter the semiconductor wafer from the back surface based on the position where the groove is detected;
Separating the semiconductor wafer into small pieces at the position of the groove and the modified region,
A method of manufacturing a semiconductor chip , wherein, in the step of forming the modified region, the power of a laser beam transmitted through the semiconductor wafer out of the laser beam incident on the semiconductor wafer is observed . Before forming the groove,
Grinding and thinning the semiconductor wafer from the back surface;
A step of attaching a dicing tape to the ground back surface,
The method of manufacturing a semiconductor chip according to claim 1, wherein in the step of detecting the position of the groove, the position of the groove is detected through the dicing tape. Fixing a plurality of chip regions having semiconductor elements formed on the surface and a semiconductor wafer having streets defined between the chip regions on a transparent chuck table;
Observing the surface of the semiconductor wafer from the surface side while being fixed to the chuck table, and detecting the position of the street;
Based on the detection result of the street position, a laser beam is incident on the semiconductor wafer from the back surface while being fixed to the chuck table, and the semiconductor wafer is modified by scanning along the street. And forming a modified region,
Separating at a position of the modified region into small pieces of the semiconductor wafer,
A method of manufacturing a semiconductor chip , wherein, in the step of forming the modified region, the power of a laser beam transmitted through the semiconductor wafer out of the laser beam incident on the semiconductor wafer is observed . In the step of fixing to the chuck table, the semiconductor wafer is fixed in a posture in which the surface of the semiconductor wafer faces the chuck table;
In the step of detecting the position of the street, in the step of observing the front surface of the semiconductor wafer through the chuck table or fixing to the chuck table, the back surface of the semiconductor wafer is in an attitude facing the chuck table. Fixing the semiconductor wafer,
4. The method of manufacturing a semiconductor chip according to claim 3 , wherein in the step of forming the modified region, the laser beam is incident on the semiconductor wafer through the chuck table.

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