Method for manufacturing a device chip

Abstract

Provided is a method for manufacturing a device chip, which can suppress an increase in cost of the device chip. The method for manufacturing a device chip includes: a bonding step (ST2) of bonding a wafer to a first surface of a semiconductor ingot; a separation step (ST3) of separating the semiconductor ingot after the bonding step (ST2) to form a layered wafer in which a part of the semiconductor ingot is layered on the wafer and a part of the semiconductor ingot after the removal; a device formation step (ST4) of, after the separation step (ST3), providing a plurality of division predetermined lines intersecting each other on a front surface of the semiconductor ingot side of the layered wafer, and forming devices in respective regions divided by the division predetermined lines; and a division step (ST5) of, after the device formation step (ST4), dividing the layered wafer along the division predetermined lines to form a plurality of device chips.

Description

Technical Field

[0001] This invention relates to a method for manufacturing device chips. Background Technology

[0002] In the manufacturing process of semiconductor device chips, the following manufacturing method is used: an insulating layer and a wiring layer are formed on a silicon wafer cut from a silicon ingot to form multiple devices, and the wafer with the devices formed is thinned and diced to manufacture a semiconductor device chip (for example, see Patent Document 1).

[0003] Patent Document 1: Japanese Patent Application Publication No. 2006-54483

[0004] In the manufacturing process of device chips, when devices are formed on SiC (silicon carbide) wafers instead of silicon wafers, it is possible to create power devices with low conduction and switching losses and high energy efficiency, as well as highly sensitive sensors that utilize cantilevered arms with high resonant frequencies. However, SiC wafers are relatively rigid, which presents challenges in thinning and processing.

[0005] In addition, the portion removed by thinning the SiC wafer is discarded, resulting in high device costs when manufacturing device chips made of expensive SiC wafers. Summary of the Invention

[0006] Therefore, the purpose of this invention is to provide a method for manufacturing device chips that can suppress the high cost of device chips.

[0007] According to the present invention, a method for manufacturing a device chip is provided, wherein the method comprises the following steps: a bonding step, wherein a wafer is bonded to a first surface of a semiconductor ingot; a separation step, wherein after the bonding step is performed, the semiconductor ingot is separated to form a stacked wafer having a portion of the semiconductor ingot stacked on the wafer and a semiconductor ingot having the portion removed; a device forming step, wherein after the separation step is performed, a plurality of intersecting predetermined dividing lines are formed on the front surface of the stacked wafer on the semiconductor ingot side, and devices are formed in each region divided by the predetermined dividing lines; and a dividing step, wherein after the device forming step, the stacked wafer is divided along the predetermined dividing lines to form a plurality of device chips.

[0008] Preferably, in this separation step, the laser beam is irradiated with a laser beam of a wavelength that is transparent to the semiconductor ingot from the second side of the back side of the semiconductor ingot located on the side where the first side of the wafer is attached, and the laser beam is focused inside the semiconductor ingot to form a separation layer. An external force is applied to the separation layer to separate the stacked wafer and the semiconductor ingot after the portion has been removed.

[0009] The preferred method for manufacturing a device chip also includes the following laser beam irradiation step: before performing the bonding step, the laser beam is irradiated to form a separation layer while the focal point of the laser beam with a wavelength that is transparent to the semiconductor ingot is positioned inside the semiconductor ingot. In the separation step, an external force is applied to the separation layer to separate it into the stacked wafer and the semiconductor ingot after the portion has been removed.

[0010] The preferred method for manufacturing a device chip includes the following steps after performing the separation step: a second bonding step, in which a second wafer is bonded to the semiconductor ingot after the portion has been removed; and a second separation step, in which, after performing the second bonding step, the semiconductor ingot is separated to form a second laminated wafer and the semiconductor ingot after the portion has been removed, with a portion of the semiconductor ingot laminated on the second wafer.

[0011] Preferably, the semiconductor ingot is a SiC ingot.

[0012] Preferably, the wafer and the semiconductor ingot are directly bonded apart by an insulating layer.

[0013] The preferred device is a metal-oxide-semiconductor field-effect transistor (MOSFET).

[0014] The preferred device is a microelectromechanical system (MEMS).

[0015] The method for manufacturing the device chip of this application can effectively reduce the high cost of the device chip. Attached Figure Description

[0016] Figure 1 This is a perspective view showing an example of a device chip manufactured by the device chip manufacturing method of the first embodiment.

[0017] Figure 2 This is a side view of a SiC ingot, which is the object of processing in the manufacturing method of the device chip according to the first embodiment.

[0018] Figure 3 yes Figure 2 The top view of the SiC ingot shown.

[0019] Figure 4 It shows that Figure 2 The diagram shows a three-dimensional view of the SiC ingot being held in place by the chuck table of the grinding apparatus.

[0020] Figure 5 This demonstrates the use of a grinding device for... Figure 2 The image shows a three-dimensional view of the first surface of a SiC ingot after planarization.

[0021] Figure 6This is a flowchart illustrating the manufacturing method of the device chip according to the first embodiment.

[0022] Figure 7 It is shown Figure 6 A three-dimensional view of the laser beam irradiation step in the manufacturing method of the device chip shown.

[0023] Figure 8 yes Figure 6 A cross-sectional view of the main part of the SiC ingot after the laser beam irradiation step in the manufacturing method of the device chip shown.

[0024] Figure 9 It is shown Figure 6 A three-dimensional diagram showing the bonding steps of the manufacturing method for the device chip.

[0025] Figure 10 It is shown Figure 6 The diagram shows a three-dimensional view of a portion of a SiC ingot being separated during the separation step of the manufacturing method of the device chip.

[0026] Figure 11 It shows that it will pass Figure 6 The diagram shows a perspective view of a portion of a device chip being separated during the separation step of the manufacturing process, with the separated portion remaining on the chuck table of the grinding apparatus.

[0027] Figure 12 This shows the grinding device for passing through Figure 6 The diagram shows a three-dimensional view of a portion of a device chip being ground during a separation step in the manufacturing process.

[0028] Figure 13 yes Figure 6 A three-dimensional view of the stacked wafer after the device formation step in the manufacturing method of the device chip shown.

[0029] Figure 14 It is shown Figure 6 A three-dimensional view of the segmentation steps in the manufacturing method of the device chip shown.

[0030] Figure 15 This is a flowchart illustrating the manufacturing method of the device chip according to the second embodiment.

[0031] Figure 16 It is shown Figure 15 A three-dimensional diagram showing the bonding steps of the manufacturing method for the device chip.

[0032] Figure 17 It is shown Figure 15 The diagram shows a three-dimensional view of the state of the separation layer formed during the separation step of the manufacturing method of the device chip.

[0033] Figure 18This is a flowchart illustrating a method for manufacturing a device chip according to a first variation of the first embodiment.

[0034] Figure 19 This is a flowchart illustrating the manufacturing method of the device chip of the first modified example of the second embodiment.

[0035] Figure 20 This is a perspective view showing the bonding steps of the manufacturing method of the device chip in the second variation of the first embodiment.

[0036] Figure 21 This is a flowchart illustrating the manufacturing method of the device chip of the third variation of the first embodiment.

[0037] Label Explanation

[0038] 1: Device chip; 4: First side; 5: Second side; 6: Device; 10: SiC ingot; 11: Part; 12: Front side; 19: Pre-defined dividing line; 20: Wafer (Second wafer); 21: Stacked wafer (Second stacked wafer); 22: Insulating layer; 43: Laser beam; 44: Focusing point; 100: Separation layer; ST1: Laser beam irradiation step; ST2, ST2-2: Bonding step; ST3, ST3-2, ST3-3: Separation step; ST4: Device formation step; ST5: Dividing step; ST12: Second bonding step; ST13: Second separation step. Detailed Implementation

[0039] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the contents described in the following embodiments. Furthermore, the constituent elements described below include contents that are readily conceived by those skilled in the art and substantially the same. Additionally, the structures described below can be appropriately combined. Furthermore, various omissions, substitutions, or modifications to the structure can be made without departing from the spirit of the present invention.

[0040] [First Implementation]

[0041] The manufacturing method of the device chip according to the first embodiment of the present invention will be described with reference to the accompanying drawings. Figure 1 This is a perspective view showing an example of a device chip manufactured by the device chip manufacturing method of the first embodiment. Figure 2 This is a side view of a SiC ingot, which is the object of processing in the manufacturing method of the device chip according to the first embodiment. Figure 3 yes Figure 2 The top view of the SiC ingot shown. Figure 4 It shows that Figure 2 The diagram shows a three-dimensional view of the SiC ingot being held in place by the chuck table of the grinding apparatus. Figure 5This demonstrates the use of a grinding device for... Figure 2 The image shows a three-dimensional view of the first surface of a SiC ingot after planarization. Figure 6 This is a flowchart illustrating the manufacturing method of the device chip according to the first embodiment.

[0042] The method for manufacturing the device chip in the first embodiment is to manufacture... Figure 1 The method shown is for device chip 1. (As...) Figure 1 As shown, the device chip 1 includes: a SiC layer 2; a silicon substrate 3, which is attached to a first surface 4 of the SiC layer 2; and a device 6, which is formed on a second surface 5 located on the back side of the first surface 4 of the SiC layer 2. Furthermore, when the device 6 is a MEMS (Micro Electromechanical Systems), the thickness of the SiC layer 2 is 40 μm or more and 80 μm or less. Furthermore, when the device 6 is a MOSFET (Metal-oxide-semiconductor Field-effect Transistor) or other power device, the thickness of the SiC layer 2 is approximately 80 μm or more and 100 μm or less.

[0043] In the first embodiment, the SiC layer 2 is made of SiC (silicon carbide), but in this invention, the material constituting the SiC layer 2 is not limited to SiC. In the first embodiment, the silicon substrate 3 is made of silicon, but in this invention, the material constituting the silicon substrate 3 is not limited to silicon. In the first embodiment, the SiC layer 2 and the silicon substrate 3 are bonded together using diffusion bonding or plasma-assist low-temperature bonding, but in this invention, methods other than diffusion bonding and plasma-assist low-temperature bonding can also be used to bond the SiC layer 2 and the silicon substrate 3 together.

[0044] In the first embodiment, device 6 is a MOSFET (Metal-oxide-semiconductor Field-effect Transistor) or MEMS (Micro Electro Mechanical Systems), but in this invention, device 6 is not limited to MOSFET and MEMS.

[0045] The device chip 1 with the above structure is manufactured as follows. Figure 2 and Figure 3 After the first surface 4 of the SiC ingot 10 shown is flattened, the wafer 20 constituting the silicon substrate 3 is attached to the first surface 4. Figure 9As shown). A portion 11 of the SiC ingot 10, bonded to the wafer 20, constitutes the SiC layer 2. Figure 11 As shown, the device chip 1 is manufactured by separating each device 6 on the front side 12 of a portion 11.

[0046] In the first embodiment, Figure 2 and Figure 3 The SiC ingot 10 shown is generally cylindrical. In the description of the SiC ingot 10, the parts that are the same as those in the device chip 1 are described using the same reference numerals.

[0047] like Figure 2 and Figure 3 As shown, the SiC ingot 10 has: a first circular facet 4; a second circular facet 5 on the back side of the first facet 4; and a peripheral facet 13 connected to the first facet 4 and the second facet 5. Additionally, the SiC ingot 10 has a first orientation plane 14 and a second orientation plane 15 perpendicular to the first orientation plane 14 on the peripheral facet 13. The length of the first orientation plane 14 is longer than the length of the second orientation plane 15.

[0048] Furthermore, the SiC ingot 10 has a c-axis 17 and a c-plane 18 perpendicular to the c-axis 17. The c-axis 17 is inclined at an angle α relative to the perpendicular line 16 of the first surface 4 in an inclination direction 23 toward the second orientation plane 15. The c-plane 18 is inclined at an angle α relative to the first surface 4 of the SiC ingot 10. Regarding the SiC ingot 10, the inclination direction 23 of the c-axis 17 from the perpendicular line 16 is perpendicular to the extension direction of the second orientation plane 15 and parallel to the first orientation plane 14. A plurality of c-planes 18 are provided in the SiC ingot 10 according to the molecular level of the SiC ingot 10. In the first embodiment, the angle α is set to 1°, 3°, or 6°, but in the present invention, the angle α can be freely set within, for example, the range of 1° to 6° to manufacture the SiC ingot 10.

[0049] In addition, the SiC ingot 10 holds the second face 5 sides in Figure 4 On the chuck table 31 of the grinding apparatus 30 shown, which rotates about its axis, as Figure 5 As shown, the grinding wheel 33 for grinding, which rotates with the spindle 32, contacts the first surface 4 and approaches the chuck table 31 at a predetermined feed rate, thereby grinding the first surface 4 using the grinding wheel 34. Alternatively, in the first embodiment, the SiC ingot 10 is held on the chuck table 41, which rotates about its axis, and the first surface 4 is ground using the grinding pad of the grinding wheel for grinding, which rotates with the spindle, to form a mirror surface.

[0050] In the first embodiment, the wafer 20 is formed as a circular plate with silicon as the substrate. In the first embodiment, the outer diameter of the wafer 20 is the same as the outer diameter of the SiC ingot 10. The thickness of the wafer 20 is only required to retain a portion 11 constituting the SiC layer 2 separated from the SiC ingot 10 and suppress damage to that portion 11; for example, it is preferably 100 μm or more and 1000 μm or less. Furthermore, in the description of the wafer 20, portions identical to those in the device chip 1 are described using the same reference numerals.

[0051] like Figure 6 As shown, the device chip manufacturing method of the first embodiment includes a laser beam irradiation step ST1, a bonding step ST2, a separation step ST3, a device formation step ST4, and a division step ST5.

[0052] (Laser beam irradiation procedure)

[0053] Figure 7 It is shown Figure 6 A three-dimensional view of the laser beam irradiation step in the manufacturing method of the device chip shown. Figure 8 yes Figure 6 The diagram shows a cross-sectional view of the main portion of the SiC ingot after the laser beam irradiation step in the manufacturing method of the device chip. The laser beam irradiation step ST1 is performed before the bonding step ST2, using a wavelength that is transparent to the SiC ingot 10. Figure 7 The laser beam 43 is irradiated with the laser beam 43 in a state where the focusing point 44 is positioned inside the SiC ingot 10, thereby forming a separation layer 100 inside the SiC ingot 10. Figure 8 The steps are shown below.

[0054] In the laser beam irradiation step ST1, the laser processing apparatus 40 holds the second surface 5 of the SiC ingot 10 on the chuck table 41, takes a picture of the SiC ingot 10 using an imaging unit (not shown), adjusts the orientation of the SiC ingot 10 to a predetermined orientation, and adjusts the relative horizontal position of the laser beam irradiation unit 42 and the SiC ingot 10. In the first embodiment, in the laser beam irradiation step ST1, the laser processing apparatus 40 aligns the second orientation plane 15 with the X-axis direction parallel to the horizontal direction, and aligns the tilt direction 23 with the Y-axis direction parallel to the horizontal direction and perpendicular to the X-axis direction.

[0055] In the laser beam irradiation step ST1, the laser processing apparatus 40 sets the focusing point 44 of the laser beam 43 irradiated from the laser beam irradiation unit 42 at a position at a desired depth 110 from the first surface 4 of the SiC ingot 10. Furthermore, the desired depth 110 is preferably a depth sufficient to generate a SiC layer 2 of the thickness necessary for forming the device 6 on the first surface 4, for example, 30 μm or more and 100 μm or less.

[0056] In the laser beam irradiation step ST1, as follows Figure 7 As shown, the laser processing apparatus 40 moves the chuck stage 41 and the laser beam irradiation unit 42 relative to each other in the X-axis direction at a predetermined feed rate, while irradiating the SiC ingot 10 with a pulsed laser beam 43 of a wavelength that is transparent to the SiC ingot 10 from the laser beam irradiation unit 42. Thus, as... Figure 8 As shown, as SiC is irradiated by a pulsed laser beam 43, it separates into Si (silicon) and C (carbon). Then, the pulsed laser beam 43 is absorbed by the previously formed C, causing SiC to separate into Si and C in a chain reaction. Cracks 102 that extend isotropically along the c-plane 18 are generated from the SiC that has separated into Si and C portions 101.

[0057] In the laser beam irradiation step ST1, when the laser processing apparatus 40 irradiates the SiC ingot 10 with the laser beam 43 over the entire length of the X-axis direction, the chuck stage 41 and the laser beam irradiation unit 42 are indexed relative to each other in the Y-axis direction within a range not exceeding the width of the crack 102. In the laser beam irradiation step ST1, the laser processing apparatus 40 repeatedly performs the actions of moving the chuck stage 41 and the laser beam irradiation unit 42 relative to each other in the X-axis direction while irradiating the laser beam 43, and performing the indexing feed of the chuck stage 41 and the laser beam irradiation unit 42 relative to each other in the Y-axis direction.

[0058] Therefore, a reduced-strength separation layer 100, consisting of SiC separated into Si and C portions 101 and cracks 102, can be formed at a desired depth 110 at a distance from the first surface 4 of the SiC ingot 10 along the Y-axis direction according to the indexing feed travel distance. When the separation layer 100 is formed at the desired depth 110 of the SiC ingot 10 along the entire length of the Y-axis direction according to the indexing feed travel distance, the process proceeds to the bonding step ST2. In addition, in the first embodiment, the SiC ingot 10 is held on the chuck table 41 of the laser processing apparatus 40 in the laser beam irradiation step ST1. However, in this invention, the chuck table 31 of the grinding apparatus 30 may be moved below the laser beam irradiation unit 42 to irradiate the SiC ingot 10 held by the chuck table 31 of the grinding apparatus 30 with a laser beam 43.

[0059] (Paste steps)

[0060] Figure 9 It is shown Figure 6This is a perspective view of the bonding steps in the manufacturing method of the device chip shown. Bonding step ST2 is the step of bonding the wafer 20 onto the first surface 4 of the SiC ingot 10. In the first embodiment, in bonding step ST2, the wafer 20 is overlapped with the first surface 4 of the SiC ingot 10, and the wafer 20 is bonded to the first surface 4 of the SiC ingot 10 by diffusion bonding or plasma-activated cryogenic bonding. However, in this invention, methods other than diffusion bonding and plasma-activated cryogenic bonding can also be used to bond the wafer 20 and the SiC ingot 10. When the wafer 20 is bonded to the first surface 4 of the SiC ingot 10, the process proceeds to separation step ST3.

[0061] (Separation Steps)

[0062] Figure 10 It is shown Figure 6 The diagram shows a three-dimensional view of a portion of a SiC ingot being separated during the separation step of the manufacturing method of the device chip. Figure 11 It shows that Figure 6 A perspective view of a portion of the device chip being separated during the separation step of the manufacturing method shown, held on the chuck table of the grinding apparatus. Figure 12 This shows the grinding device for... Figure 6 A perspective view of a portion of the device chip being ground during the separation step of the manufacturing method shown.

[0063] Separation step ST3 is as follows: After performing bonding step ST2, the SiC ingot 10 is separated to form a portion 11 of the SiC ingot 10. Figure 11 The laminated wafer 21 obtained by stacking on wafer 20 (as shown) and the remaining SiC ingot 10 after a portion of 11 has been removed. In separation step ST3, the second surface 5 of the SiC ingot 10 is placed on a substrate disposed on... Figure 10 After the water tank 50 is placed inside the cylindrical body 51 and on the freely lifting and lowering holding table 52, the holding table 52 is lowered to store the SiC ingot 10 with the wafer 20 attached inside the water tank 50.

[0064] In separation step ST3, water is supplied to the water tank 50 until the SiC ingot 10 to which the wafer 20 is attached is submerged, causing an ultrasonic transducer made of piezoelectric ceramic (not shown) or the like to operate in the water. Alternatively, when operating the ultrasonic transducer, it can be in contact with the SiC ingot 10, or a gap (e.g., 2 mm or more and 3 mm or less) can be provided between the ultrasonic transducer and the SiC ingot 10.

[0065] In separation step ST3, when the ultrasonic transducer is activated, the separation layer 100 is destroyed by ultrasonic stimulation. In separation step ST3, a portion 11 of the SiC ingot 10 closer to the wafer 20 than the separation layer 100 is separated from the remaining SiC ingot 10 along with the wafer 20, starting from the separation layer 100. Alternatively, in this invention, the action of separating the portion 11 from the SiC ingot 10 can be performed mechanically by applying an impact to the separation layer 100 using a tool such as a chisel whose thickness decreases towards the front end. In separation step ST3, as... Figure 11 As shown, a portion 11 of the SiC ingot 10 is stacked on the wafer 20 to form a stacked wafer 21, and a portion 11 of the SiC ingot 10 is removed from the wafer 20. In addition, a separation layer 100 is formed on the first surface 4 of the remaining SiC ingot 10.

[0066] In separation step ST3, such as Figure 12 As shown, the grinding apparatus 70 attracts and holds the wafer 20 side of the stacked wafer 21 on the chuck stage 71. In the separation step ST3, the grinding apparatus 70 rotates the chuck stage 71 about its axis, causing the grinding wheel 73, which rotates via the spindle 72, to contact the front surface 12 of the SiC ingot 10 where the separation layer 100 is formed, and to approach the chuck stage 71 at a predetermined feed rate, thereby grinding and planarizing the front surface 12 using the grinding wheel 74. After grinding, the front surface 12 can be polished to a mirror finish. When the front surface 12 of the SiC ingot 10 is planarized, the process proceeds to the device formation step ST4.

[0067] (Device formation steps)

[0068] Figure 13 yes Figure 6 The diagram shows a perspective view of a stacked wafer after the device formation step in the manufacturing method of the device chip. Device formation step ST4 is as follows: After separation step ST3, multiple intersecting predetermined dividing lines 19 are formed on the front side 12 of a portion 11 of the SiC ingot 21, and devices 6 are formed in each region divided by the predetermined dividing lines 19. In device formation step ST4, the front side 12 of a portion 11 of the stacked wafer 21 is divided into multiple regions by the grid-like predetermined dividing lines 19, and devices 6 are formed in each region. When devices 6 are formed on the front side 12 of a portion 11 of the SiC ingot 10, the process proceeds to separation step ST5.

[0069] (Segmentation steps)

[0070] Figure 14 It is shown Figure 6The diagram shows a perspective view of the dicing steps in the manufacturing method of the device chip. Dividing step ST5 is the following step: after performing the device formation step ST4, the stacked wafer 21 is divided along the predetermined dicing line 19 to form a plurality of device chips 1.

[0071] In the first embodiment, in the dicing step ST5, a dicing tape 121 with an annular frame 120 attached to the outer edge of the wafer 20 side of the stacked wafer 21 is attached. The cutting device 60 draws and holds the wafer 20 side of the stacked wafer 21 onto a chuck stage (not shown) through the dicing tape 121. In the dicing step ST5, the cutting device 60 uses an imaging unit to photograph the front side 12 of a portion 11 of the SiC ingot 10 of the stacked wafer 21, detects the dicing predetermined line 19, and performs alignment of the cutting tool 62 of the cutting unit 61 with the dicing predetermined line 19.

[0072] In the segmentation step ST5, the cutting device 60 moves the chuck table and the cutting tool 62 relative to each other along the predetermined segmentation line 19, while... Figure 14 As shown, the cutting tool 62 cuts into the dicing tape 121, and the cutting tool 62 cuts (cuts) the predetermined dicing lines 19 to divide the stacked wafer 21 into individual device chips 1. When the cutting device 60 has cut all the predetermined dicing lines 19, the manufacturing method of the device chips ends. The device chips 1 obtained one by one are picked up from the dicing tape 121 by a known pick-up device.

[0073] In addition, in the first embodiment, in the dicing step ST5, the stacked wafer 21 is diced into individual device chips 1 by a so-called cutting process. In the present invention, the stacked wafer 21 may also be diced into individual device chips 1 by ablation processing using a laser beam of a wavelength that is absorptive to a portion 11 of the SiC ingot 10 and the wafer 20 along the dicing predetermined line 19, forming a modified layer by a laser beam of a wavelength that is transmissive to a portion 11 of the SiC ingot 10 and the wafer 20 along the dicing predetermined line 19, or by plasma cutting by plasma etching of the stacked wafer 21 along the dicing predetermined line 19.

[0074] As described above, the device chip manufacturing method of the first embodiment involves attaching a wafer 20 to a SiC ingot 10, separating the SiC ingot 10 into a portion 11 attached to the wafer 20 to form a stacked wafer 21 and the remaining SiC ingot 10. The device chip manufacturing method involves forming a device 6 on the front side 12 of the separated portion 11 of the SiC ingot 10 of the stacked wafer 21, and manufacturing the device chip 1 by dicing along a predetermined dicing line 19.

[0075] Therefore, in the device chip manufacturing method, even if the thickness of the portion 11 separated from the SiC ingot 10 is suppressed, the mechanical strength of the stacked wafer 21 can be ensured by the wafer 20. As a result, the device chip manufacturing method can suppress the amount of grinding when planarizing the front side 12 of the portion 11 of the SiC ingot 10 separated from the remaining SiC ingot 10, and the stacked wafer 21 is not thinned, thus simplifying the manufacturing process and reducing the amount of waste from the SiC ingot 10.

[0076] Furthermore, the device chip manufacturing method can suppress the amount of grinding during planarization of the front side 12 of a portion 11 of the SiC ingot 10. In the dicing step ST5, the thinned portion of the SiC ingot 10 and the wafer 20 are diced along the predetermined dicing line 19 to suppress SiC processing, thus suppressing the processing-related time. As a result, the device chip manufacturing method can effectively reduce the high cost of the device chip 1.

[0077] [Second Implementation]

[0078] The manufacturing method of the device chip according to the second embodiment of the present invention will be described with reference to the accompanying drawings. Figure 15 This is a flowchart illustrating the manufacturing method of the device chip according to the second embodiment. Figure 16 It is shown Figure 15 A three-dimensional diagram showing the bonding steps of the manufacturing method for the device chip. Figure 17 It is shown Figure 15 The diagram shows a three-dimensional view of the state of the separation layer formed during the separation step of the manufacturing method of the device chip. Figure 15 , Figure 16 as well as Figure 17 In this document, the parts that are the same as those in the first embodiment are marked with the same reference numerals and the descriptions are omitted.

[0079] like Figure 15 As shown, the device chip manufacturing method of the second embodiment includes a pasting step ST2-2, a separation step ST3-2, a device formation step ST4, and a division step ST5. The pasting step ST2-2 and the separation step ST3-2 are different from the pasting step ST2 and the separation step ST3 of the first embodiment, and do not have a laser beam irradiation step ST1. Apart from this, the device chip manufacturing method of the second embodiment is the same as that of the first embodiment.

[0080] The bonding step ST2-2 of the device chip manufacturing method of the second embodiment is the same as that of the first embodiment, which is the step of bonding the wafer 20 to the first surface 4 of the SiC ingot 10. In the second embodiment, as... Figure 16As shown, in the pasting step ST2-2, the wafer 20 is pasted onto the first surface 4 of the SiC ingot 10 where the separation layer 100 has not been formed, using the same method as in the first embodiment. When the wafer 20 is pasted onto the first surface 4 of the SiC ingot 10 where the separation layer 100 has not been formed, the process proceeds to the separation step ST3-2.

[0081] The separation step ST3-2 of the device chip manufacturing method of the second embodiment is as follows: irradiating the SiC ingot 10 with a laser beam 43 having a wavelength that is transparent to the SiC ingot 10 at a focal point 44 located on the second side 5 of the back side of the first side 4 on which the wafer 20 is attached, and forming a separation layer 100 inside the SiC ingot 10, applying an external force to the separation layer 100 to separate the SiC ingot 10 into a portion 11 constituting the stacked wafer 21 and the remaining SiC ingot 10 after the portion 11 is removed.

[0082] In the separation step ST3-2 of the device chip manufacturing method of the second embodiment, the laser processing apparatus 40 holds the first surface 4 side of the SiC ingot 10 on the chuck stage 41 with the wafer 20 in between, and takes a picture of the SiC ingot 10 using the imaging unit, so that the second orientation plane 15 is parallel to the X-axis direction, the tilt direction 23 is parallel to the Y-axis direction, and the relative position of the laser beam irradiation unit 42 and the horizontal direction of the SiC ingot 10 is adjusted.

[0083] In separation step ST3-2, the laser processing apparatus 40 sets the focusing point 44 of the laser beam 43 irradiated by the laser beam irradiation unit 42 at a position at a desired depth 110 from the first surface 4 of the SiC ingot 10, similar to the first embodiment. Figure 17 As shown, while the chuck stage 41 and the laser beam irradiation unit 42 are moved relative to each other in the X-axis direction at a predetermined feed speed, a pulsed laser beam 43 with a wavelength that is transparent to the SiC ingot 10 is irradiated from the laser beam irradiation unit 42.

[0084] In the separation step ST3-2, the laser processing apparatus 40 repeats the same actions as in the laser beam irradiation step ST1 of the device chip manufacturing method of the first embodiment: moving the chuck stage 41 and the laser beam irradiation unit 42 relative to each other in the X-axis direction while irradiating the laser beam 43, and performing a relative indexing feed operation on the chuck stage 41 and the laser beam irradiation unit 42 relative to each other in the Y-axis direction. In the separation step ST3-2, a separation layer 100 with reduced strength is formed at a desired depth 110 from the first surface 4 of the SiC ingot 10, consisting of SiC separated into Si and C portions 101 and cracks 102.

[0085] In the separation step ST3-2, after the separation layer 100 is formed, similar to the separation step ST3 of the device chip manufacturing method of the first embodiment, the SiC ingot 10 is broken starting from the separation layer 100, and separated into a stacked wafer 21 obtained by stacking a portion 11 of the SiC ingot 10 on the wafer 20, and the remaining SiC ingot 10 after a portion 11 is removed, and proceeds to the device formation step ST4.

[0086] The device chip manufacturing method of the second embodiment involves attaching a wafer 20 to a SiC ingot 10, separating the SiC ingot 10 into a portion 11 attached to the wafer 20 to form a stacked wafer 21 and the remaining SiC ingot 10. In the device chip manufacturing method of the second embodiment, a device 6 is formed on the front side 12 of the separated portion 11 of the SiC ingot 10 of the stacked wafer 21, and the device chip 1 is manufactured by dicing along a predetermined dicing line 19.

[0087] Therefore, in the device chip manufacturing method of the second embodiment, even if the thickness of the portion 11 separated from the SiC ingot 10 is suppressed, the mechanical strength of the stacked wafer 21 can be ensured by the wafer 20, the manufacturing process can be simplified, the amount of waste from the SiC ingot 10 can be reduced, and the processing of SiC can be suppressed, thereby reducing the processing time required. Thus, the device chip manufacturing method of the second embodiment, like the first embodiment, achieves the effect of suppressing the high cost of the device chip 1.

[0088] [First Variation]

[0089] The manufacturing method of the device chip of the first embodiment and the first modified example of the second embodiment of the present invention will be described with reference to the accompanying drawings. Figure 18 This is a flowchart illustrating a method for manufacturing a device chip according to a first variation of the first embodiment. Figure 19 This is a flowchart illustrating the manufacturing method of the device chip of the first modified example of the second embodiment. Figure 18 and Figure 19 In this document, the parts that are the same as those in the first and second embodiments are marked with the same reference numerals and the descriptions are omitted.

[0090] like Figure 18 and Figure 19As shown, the device chip manufacturing method of the first variation includes a second bonding step ST12 and a second separation step ST13 after the dividing step ST5 in the first and second embodiments. When the thickness of the remaining SiC ingot 10 is a predetermined thickness or more (step ST11: no), the second bonding step ST12 and the second separation step ST13 are performed. After the second separation step ST13, the process proceeds to the device formation step ST4. Otherwise, it is the same as in the first and second embodiments. Furthermore, in the first variation, the predetermined thickness is the thickness of a portion 11 of the SiC ingot 10.

[0091] The second bonding step ST12 is as follows: After performing the division step ST5, that is, after performing the separation step ST3, the wafer 20, which is the second wafer, is bonded to the first surface 4 of the remaining SiC ingot 10 after a portion 11 has been removed. In the second bonding step ST12, the wafer 20 is bonded to the first surface 4 of the remaining SiC ingot 10 using the same method as in the bonding step ST2-2 of the second embodiment, and then proceeds to the second separation step ST13. Furthermore, in this invention, the first surface 4 can be ground or polished to a mirror finish before bonding the wafer 20 to the remaining SiC ingot 10.

[0092] The second separation step ST13 is as follows: After performing the second bonding step ST12, the SiC ingot 10 is separated to form a second stacked wafer 21, which is a portion 11 of the SiC ingot 10 stacked on the wafer 20, and the remaining SiC ingot 10 after the portion 11 is removed. The second separation step ST13 uses the same method as the separation step ST3-2 in the second embodiment to separate the SiC ingot 10 into a portion 11 constituting the stacked wafer 21 and the remaining SiC ingot 10, and proceeds to the device formation step ST4.

[0093] In addition, when the thickness of the remaining SiC ingot 10 after the division step ST5 is less than the specified thickness (step ST11: yes), the manufacturing method of the device chip of the first modified example ends.

[0094] Thus, the device chip manufacturing method of the first variation cuts out a portion 11 of the SiC ingot 10 to form a laminated wafer 21 to manufacture the device chip 1 until the thickness of the remaining SiC ingot 10 is less than a predetermined thickness.

[0095] The method for manufacturing the device chip in the first modification involves attaching a wafer 20 to a SiC ingot 10, separating the SiC ingot 10 into a portion 11 constituting the stacked wafer 21 and the remaining SiC ingot 10, forming a device 6 on the front side 12 of the portion 11 of the SiC ingot 10, and manufacturing the device chip 1 by dicing along a predetermined dicing line 19. As a result, the method for manufacturing the device chip in the first modification, like the first and second embodiments, achieves the effect of suppressing the high cost of the device chip 1.

[0096] In addition, the device chip manufacturing method of the first modified example cuts out a portion 11 of the SiC ingot 10 to form a laminated wafer 21 to manufacture the device chip 1 until the thickness of the remaining SiC ingot 10 is less than a specified thickness, thus suppressing the amount of waste SiC ingot 10.

[0097] [Second Variation]

[0098] The manufacturing method of the device chip of the first embodiment and the second modification of the second embodiment of the present invention will be described with reference to the accompanying drawings. Figure 20 This is a perspective view showing the bonding steps of the manufacturing method of the device chip in the second variation of the first embodiment. Figure 20 In this document, the parts that are the same as those in the first and second embodiments are marked with the same reference numerals and the descriptions are omitted.

[0099] In the bonding step ST2 of the second variation, an insulating layer 22 is formed on the front side of the silicon substrate 3 of the wafer 20. The wafer 20 and the SiC ingot 10 are directly bonded through the insulating layer 22 by diffusion bonding or plasma-activated low-temperature bonding. Additionally, in Figure 20 In the example shown, an insulating layer 22 made of SiO2 is formed on the front side 12 of the silicon substrate 3 of the wafer 20. However, in this invention, the material constituting the insulating layer 22 is not limited to SiO2. Furthermore, in Figure 20 In the example shown, an insulating layer 22 is formed on the front side 12 of the silicon substrate 3 of the wafer 20. However, in this invention, the insulating layer 22 may also be formed on the first surface 4 of the SiC ingot 10. In summary, in this invention, the insulating layer 22 may be formed on at least one of the front side 12 of the silicon substrate 3 of the wafer 20 and the first surface 4 of the SiC ingot 10.

[0100] The second variation of the device chip manufacturing method involves attaching a wafer 20 to a SiC ingot 10, separating the SiC ingot 10 into a portion 11 constituting a stacked wafer 21 and the remaining SiC ingot 10, forming a device 6 on the front side 12 of the portion 11 of the SiC ingot 10, and manufacturing the device chip 1 by dividing along a predetermined dividing line 19. Therefore, it achieves the same effect as the first and second embodiments in suppressing the high cost of the device chip 1.

[0101] In recent years, the development and manufacturing of device chips with a structure known as SOI (Silicon on Insulator) has begun. This SOI device chip is manufactured by directly bonding two wafers through an insulating layer and thinning one of the wafers into a thin film. Compared to this conventional processing, the manufacturing method of the second variation directly bonds the wafer 20 and the SiC ingot 10 through the insulating layer 22, thereby enabling the easy manufacture of a device chip 1 with an SOI structure embedded in the insulating layer 22.

[0102] in addition, Figure 20 Taking the bonding step ST2 of the device chip manufacturing method of the second modification of the first embodiment as an example, in the present invention, in the bonding step ST2-2 of the second modification of the second embodiment, with Figure 20 Similarly, in the example shown, an insulating layer 22 is formed on at least one of the front side 12 of the silicon substrate 3 of the wafer 20 and the first side 4 of the SiC ingot 10, and the wafer 20 and the SiC ingot 10 are directly bonded through the insulating layer 22 by diffusion bonding or plasma-activated low-temperature bonding.

[0103] [3rd Variation]

[0104] The manufacturing method of the device chip of the third modified example of the first embodiment of the present invention will be described with reference to the accompanying drawings. Figure 21 This is a flowchart illustrating the manufacturing method of the device chip of the third variation of the first embodiment. Figure 21 In this document, the parts that are the same as those in the first embodiment are marked with the same reference numerals and the descriptions are omitted.

[0105] The method for manufacturing the device chip in the third variation does not perform the laser beam irradiation step ST1. Instead, in the separation step ST3-3, a wire cutting machine for electrical discharge machining is used to separate the SiC ingot 10 into a portion 11 constituting the stacked wafer 21 and the remaining SiC ingot 10. Otherwise, it is the same as the first embodiment.

[0106] The method for manufacturing the device chip in the third variation involves attaching the wafer 20 to the SiC ingot 10, separating the SiC ingot 10 into a portion 11 constituting the stacked wafer 21 and the remaining SiC ingot 10, forming the device 6 on the front side 12 of the portion 11 of the SiC ingot 10, and manufacturing the device chip 1 by dividing along the predetermined dividing line 19. Therefore, it has the same effect as the first and second embodiments in suppressing the high cost of the device chip 1.

[0107] in addition, Figure 21The method for manufacturing a device chip in the third variation of the first embodiment is representatively shown. However, in the third variation of the second embodiment of the present invention, the separation step ST3-3 is also similar to... Figure 20 The example shown also uses a wire EDM machine to separate SiC ingot 10.

[0108] Furthermore, in the above embodiments, SiC ingot 10 was described as an ingot, but the ingot is not limited to SiC ingot. The present invention can also be applied to semiconductor ingots such as hexagonal single crystal ingots and silicon ingots.

Claims

1. A manufacturing method of a device chip, wherein the manufacturing method of the device chip has the steps of: a bonding step of bonding a wafer constituting a part of the device chip to a first surface of a semiconductor ingot; a separation step of separating the semiconductor ingot after the bonding step is performed, thereby forming a layered wafer in which a part of the semiconductor ingot constituting a part of the device chip is layered on the wafer and the semiconductor ingot from which the part is removed; a device formation step of, after the separation step is performed, providing a plurality of division predetermined lines intersecting each other on a front surface of the semiconductor ingot side of the layered wafer, and forming devices respectively in regions divided by the division predetermined lines; and a division step of, after the device formation step is performed, dividing the entire layered wafer formed by the layered wafer of the part of the semiconductor ingot and the wafer along the division predetermined lines to form a plurality of device chips.

2. The manufacturing method of the device chip according to claim 1, wherein in the separation step, a separation layer is formed by irradiating a laser beam having a wavelength that is transparent to the semiconductor ingot from a second surface of the semiconductor ingot on a back surface side of the first surface to which the wafer is bonded, in a state where a focal point of the laser beam is positioned inside the semiconductor ingot, an external force is given to the separation layer, thereby separating into the layered wafer and the semiconductor ingot from which the part is removed.

3. The manufacturing method of the device chip according to claim 1, wherein the manufacturing method of the device chip further has a laser beam irradiation step of, before the bonding step is performed, forming a separation layer by irradiating a laser beam having a wavelength that is transparent to the semiconductor ingot in a state where a focal point of the laser beam is positioned inside the semiconductor ingot, in the separation step, an external force is given to the separation layer, thereby separating into the layered wafer and the semiconductor ingot from which the part is removed.

4. The manufacturing method of the device chip according to claim 1 or 2, wherein the manufacturing method of the device chip further has the steps of: a second bonding step of bonding a second wafer to the semiconductor ingot from which the part is removed, after the separation step is performed; and a second separation step of separating the semiconductor ingot after the second bonding step is performed, thereby forming a second layered wafer in which a part of the semiconductor ingot is layered on the second wafer and the semiconductor ingot from which the part is removed.

5. The manufacturing method of the device chip according to claim 1 or 2, wherein the semiconductor ingot is a SiC ingot.

6. The manufacturing method of the device chip according to claim 1 or 2, wherein the wafer and the semiconductor ingot are directly joined with an insulating layer interposed therebetween.

7. The manufacturing method of the device chip according to claim 1 or 2, wherein the device is a metal oxide semiconductor field effect transistor.

8. The manufacturing method of the device chip according to claim 1 or 2, wherein the device is a micro electro mechanical system.

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