Chip manufacturing methods

Abstract

[Problem] To manufacture wafers without defects during lamination and thermoforming by dicing a wafer with a resin layer. [Solution] A wafer manufacturing method comprising: dicing a wafer having a resin layer on its first side along a predetermined processing line to manufacture wafers; a protective film forming step, wherein a protective film is formed on the first side; a processing trench forming step, wherein, after the protective film forming step, a first laser beam of an absorptive wavelength is irradiated onto the wafer from the first side along the predetermined processing line to form a processing trench on the wafer; a hardened area removal step, wherein, after the processing trench forming step, a hardened area of ​​the hardened resin layer is removed; and a protective film removal step, wherein, after the hardened area removal step, the protective film formed on the first side is removed. The wafer manufacturing method forms individual wafers by dicing the wafer along the processing trench.

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a wafer, which involves dicing a wafer having a resin layer to manufacture a wafer. [Previous Technology]

[0002] In the manufacturing process of component chips used in electronic devices such as mobile phones or personal computers, firstly, multiple intersecting pre-defined processing lines (dicing lines) are set on the front side of a wafer made of materials such as semiconductors. Then, components such as ICs (Integrated Circuits) and LSIs (Large-scale Integrated Circuits) are formed in the areas divided by these pre-defined processing lines. Subsequently, if the wafer is cut along these pre-defined processing lines, individual component chips are formed.

[0003] In wafer dicing, for example, a laser processing apparatus is used to laser process the wafer using a laser beam. The laser processing apparatus, for example, irradiates the wafer with a laser beam of wavelength that the wafer can absorb along a predetermined processing line, thereby performing an ablation process on the wafer.

[0004] In recent years, in order to reduce the mounting area of ​​component chips, technologies such as HBM (High Bandwidth Memory) have been developed, which vertically stacks multiple chips and electrically connects them to each other through TSV (Through Silicon Via) and integrates them. In addition, a resin layer called NCF (Non-Conductive Film) has been developed for use in stacking multiple chips (see Patent Document 1 and Patent Document 2).

[0005] If a resin layer is disposed on the front side of a wafer before it is split into wafers, and the wafer is irradiated with a laser beam to slit the wafer together with the resin layer, a wafer with a resin layer on one side can be obtained. Then, if the obtained wafers are stacked to form a laminate, and the wafers are thermally bonded by pushing the laminate from above and below while expanding each resin layer and heating it, a wafer that is attached to each other and integrated by the resin layers can be obtained. [Contemporary Art Documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2009-277818 [Patent Document 2] Japanese Patent Application Publication No. 2016-92188 [Summary of the Invention]

[0007] [Problem to be Solved by the Invention] However, when a wafer with a resin layer is ablated using a laser beam, the resin layer partially deteriorates and hardens around the irradiated area due to the heat generated by the laser beam. Then, when multiple wafers are laminated and thermally bonded, the hardened area of ​​the resin layer does not easily extend, and air bubbles entering the hardened area of ​​the resin layer are not easily eliminated.

[0008] Therefore, if a hardened area is formed in the resin layer, there may be situations where the hot pressing is not performed properly and the individual wafers are not integrated with the intended quality, the integrated wafers become easy to separate, and unnecessary electrical connections are formed through air bubbles. In other words, partial hardening of the resin layer can become a cause of wafer defects.

[0009] The present invention was made in view of these problems, and its object is to provide a method for manufacturing a wafer by dividing a wafer having a resin layer disposed thereon to manufacture a wafer, and without producing wafer defects when the wafer is laminated and thermally bonded.

[0010] [Technical Means for Solving the Problem] According to one aspect of the present invention, a method for manufacturing a wafer is provided, which manufactures a wafer by dicing a wafer having a resin layer on a first surface along a predetermined processing line, characterized in that it includes: a protective film forming step, which forms a protective film on the first surface; a processing trench forming step, which, after the protective film forming step, irradiates the wafer with a first laser beam of an absorptive wavelength from the first surface side along the predetermined processing line to form a processing trench on the wafer; a hardened region removal step, which, after the processing trench forming step, removes the hardened region of the hardened resin layer; and a protective film removal step, which, after the hardened region removal step, removes the protective film formed on the first surface, and the wafer manufacturing method forms individual wafers by dicing the wafer along the processing trench.

[0011] Preferably, in the hardened area removal step, the hardened area is removed by irradiating the area containing the resin layer with a second laser beam.

[0012] Furthermore, preferably, the energy density of the second laser beam is lower than the energy density of the first laser beam.

[0013] Furthermore, preferably, the first laser beam is a Gaussian beam and the second laser beam is a top-hat beam.

[0014] Preferably, in the hardened area removal step, the wafer is irradiated with the second laser beam, which has a width wider than the width of the processing tank.

[0015] Furthermore, preferably, in the hardened area removal step, the second laser beam is shaped into an ellipse with different lengths of the major axis and minor axis, a rectangle with different lengths of the long side and short side, or a square with equal lengths of all four sides, and the wafer is irradiated with the second laser beam with the major axis, the long side, or one of the sides facing a direction perpendicular to the predetermined processing line.

[0016] Furthermore, preferably, in the hardened area removal step, the second laser beam is irradiated in one or both of a direction parallel to and perpendicular to the predetermined processing line of the wafer.

[0017] Furthermore, preferably, in the hardened region removal step, the region containing the resin layer is irradiated with the second laser beam under conditions less than the threshold at which the resin layer would harden.

[0018] Furthermore, preferably, in the hardened area removal step, the hardened area of ​​the resin layer is cut with a cutting blade.

[0019] Then, preferably, in the process groove forming step, the first laser beam is irradiated onto the wafer by splitting it in one or both of a direction parallel to and perpendicular to the predetermined processing line of the wafer.

[0020] Furthermore, preferably, the resin layer is NCF.

[0021] Furthermore, preferably, the thickness of the protective film is 5 μm or more.

[0022] Furthermore, preferably, the processing groove formed in the processing groove forming step does not reach the second surface of the wafer that is parallel to the first surface, and the wafer is divided along the processing groove by applying an external force to the wafer.

[0023] [Effects of the Invention] In the method for manufacturing a wafer according to one aspect of the present invention, a protective film is formed on the first side of a wafer having a resin layer on the first side, and the wafer is diced by irradiating a first laser beam. At this time, although a hardened region is formed in the resin layer, this hardened region is subsequently removed, and the protective film is removed from the first side. In this case, no hardened region of the resin layer hardened by the first laser beam remains in the resulting wafer. Therefore, when multiple resulting wafers are laminated and thermally bonded, wafer defects caused by the hardened region will not occur.

[0024] Therefore, according to one aspect of the present invention, a method for manufacturing a wafer is provided, which manufactures a wafer by dicing a wafer having a resin layer disposed thereon, and does not produce wafer defects when the wafer is laminated and thermally bonded.

Implementation Method

[0026] An embodiment of the present invention will be described with reference to the accompanying drawings. In the wafer manufacturing method of this embodiment, a wafer having a resin layer on its first surface is diced along a predetermined processing line to manufacture individual wafers. First, the wafer that becomes the work to be processed in the wafer manufacturing method of this embodiment will be described. FIG1 is a schematic perspective view of a wafer 1 having a resin layer 7 disposed on its first surface (front side) 1a.

[0027] Wafer 1 is, for example, a circular wafer made of materials such as Si (silicon), SiC (silicon carbide), GaN (gallium nitride), GaAs (gallium arsenide), or other semiconductors. A first surface 1a of wafer 1 is divided by multiple intersecting pre-defined processing lines 3. Furthermore, IC, LSI, and other components 5 are formed in each region divided by the pre-defined processing lines 3 on the first surface 1a of wafer 1.

[0028] However, there are no restrictions on the material, shape, structure, size, etc. of wafer 1. For example, a substrate made of other semiconductor, ceramic, resin, metal, or other materials may also be used as wafer 1. Furthermore, there are no restrictions on the type, quantity, shape, structure, size, or arrangement of components 5, and wafer 1 may not have components 5 formed on it.

[0029] If a wafer 1 on the first surface 1a, on which a plurality of components 5 are disposed, is diced along a predetermined processing line 3, a plurality of wafers each having components 5 can be obtained. The wafer 1 is loaded into the processing apparatus and diced in the state of the frame unit 13 shown in FIG1. ​​That is, the processed and diced wafer 1 can be pre-integrated with the adhesive film 9, which is called the dicing film, and the annular frame 11, and the frame unit 13 can be formed.

[0030] If the wafer 1 is processed through the frame 11 and the adhesive film 9, the wafer 1 can be protected from impacts during wafer 1 transport, thus making wafer 1 processing easier. Furthermore, the individual chips formed by dicing the wafer 1 are supported by the adhesive film 9, thus making chip processing easier. Subsequently, if the adhesive film 9 is expanded radially outward from the inside of the opening in the frame 11, the spacing between the chips widens, making chip picking easier.

[0031] The adhesive film 9 comprises: a flexible sheet-like substrate and an adhesive layer disposed on the substrate. The substrate may be, for example, PO (polyolefin), PET (polyethylene terephthalate), polyvinyl chloride, polystyrene, etc. Furthermore, the adhesive layer may be, for example, silicone rubber, acrylic materials, epoxy materials, etc.

[0032] The annular frame 11 is formed of a material such as metal and has an opening with a diameter larger than that of the wafer 1. An adhesive film 9 is pre-attached to the periphery of the opening of the frame 11 in a manner that closes the opening, with the adhesive surface of the adhesive film 9 exposed at the opening. Then, if the wafer 1 is attached to the adhesive surface exposed in the opening of the adhesive film 9 attached to the frame 11, a frame unit 13 can be formed.

[0033] The wafer obtained from dicing wafer 1 is used to mount to a predetermined mounting object. In recent years, in order to reduce the mounting area of ​​the wafer, increase the functionality of the wafer / reduce power consumption, etc., multiple wafers are stacked vertically and electrically connected to each other and integrated. For example, if a resin film is sandwiched between each wafer, and the wafers are connected to each other by TSV and the wafer laminate is thermo-bonded, then each wafer is attached and integrated by the softened resin film.

[0034] Here, the operation of separately depositing resin films on individual wafers obtained by dicing wafer 1 is inefficient. Therefore, a resin layer 7, called NCF, is pre-deposited on the first surface 1a of the wafer 1 to be diced, and the wafer 1 is diced together with the resin layer 7. In this case, individual wafers having the resin layer 7 on one side can be formed efficiently.

[0035] To deposit the resin layer 7 on the first surface 1a of the wafer 1, for example, a resin film formed in sheet form can be attached to the first surface 1a. Alternatively, liquid resin can be coated onto the first surface 1a and cured to deposit the resin layer 7. The resin layer 7 may be composed of materials such as polyolefin, polyester, epoxy resin, acrylic resin, silicone resin, polyimide resin, etc., or a combination thereof. Various functional additives may also be incorporated into the resin layer 7, and the composition of the resin layer 7 is not particularly limited.

[0036] When the wafers formed from wafer 1 are laminated to form a laminate, and the laminate is heated at a predetermined temperature while being pressed with a predetermined force, the resin layer 7 will soften and expand appropriately. Then, if the heating of the laminate is stopped, the resin layer 7 will harden and attach the wafers to each other.

[0037] For example, wafer 1 is a thin silicon wafer with a thickness of about 50 μm, and the resin layer 7 has a thickness of about 20 μm. For example, the width of the processing predetermined line 3 is set to about 80 μm, and a 5 mm square wafer is manufactured from wafer 1. As a method for dividing wafer 1, although cutting with a circular cutting blade is also considered, if thin wafer 1 is cut, a notch called a chipping is easily formed on the second surface 1b.

[0038] Furthermore, the following method is also considered: focusing a laser beam of wavelength that penetrates wafer 1 onto wafer 1 to form a modified layer, and using the modified layer as a starting point, forming vertically extending cracks to divide wafer 1. However, when wafer 1 is thin, it becomes impossible to ignore the deviation in the formation height of the modified layer caused by the deviation in the thickness of the adhesive film 9. That is, it becomes difficult to divide wafer 1 uniformly along the predetermined processing line 3.

[0039] Therefore, a laser processing apparatus can be used in the dicing of wafer 1, which can irradiate wafer 1 with a laser beam of an absorptive wavelength (a wavelength that absorptive to wafer 1) along the predetermined processing line 3 to perform ablation processing on wafer 1. If wafer 1 is ablated along the predetermined processing line 3, a processing groove is formed on wafer 1 along the predetermined processing line 3, and wafer 1 is diced along the processing groove to obtain individual wafers. At this time, the resin layer 7 disposed on the first surface 1a of wafer 1 is also broken.

[0040] However, around the area where the processing groove is formed, the resin layer 7 is heated by the heat generated by the laser beam, causing the resin layer 7 to partially deteriorate and harden. Therefore, hardened areas remain in the resin layer 7 along the edges of each formed wafer. When multiple wafers are thermo-bonded, the hardened areas of the resin layer 7 do not easily extend and expand properly, and air bubbles entering the hardened areas of the resin layer 7 are also difficult to eliminate.

[0041] Therefore, there may be situations where individual chips are not properly integrated by thermoforming, integrated chips become easily separable, and unnecessary electrical connections are formed through air bubbles. That is, there may be situations where partial hardening of the resin layer 7 becomes a cause of chip defects.

[0042] Therefore, by means of the wafer manufacturing method of this embodiment, a wafer that does not produce wafer defects during lamination and thermal bonding is manufactured. Hereinafter, each step of the wafer manufacturing method of this embodiment will be described. FIG10 is a flowchart showing the process of each step of the wafer manufacturing method of this embodiment.

[0043] In the wafer manufacturing method of this embodiment, a protective film formation step S10 is first performed. FIG2 is a schematic cross-sectional view of the protective film formation step S10. In the protective film formation step S10, a protective film is formed on the first surface 1a of the wafer 1.

[0044] The protective film formation step S10 is performed, for example, by a spin coater 2. The spin coater 2 includes: a chuck stage 6, which rotatably supports the wafer 1 (frame unit 13); and a liquid resin supply nozzle 14, which supplies liquid resin 16, a material for forming a protective film, to the wafer 1 supported by the chuck stage 6.

[0045] The chuck stage 6 includes: a frame 10 having a recess with an opening at the top; and a porous member 12 housed in the recess of the frame 10. An attraction path (not shown) is formed in the frame 10, one end of which is connected to an attraction source (not shown), and the other end is connected to the porous member 12. If a wafer 1 is placed on the chuck stage 6 through a film 9, and the attraction source is operated to apply negative pressure to the wafer 1, the chuck stage 6 can be used to attract and hold the wafer 1.

[0046] A plurality of clamps 8 are arranged around the chuck table 6, which can hold the frame 11 of the frame unit 13 placed on the chuck table 6. Furthermore, a base 4 supporting the chuck table 6 is connected to the center of the bottom surface of the frame 10 of the chuck table 6. A rotary drive source (not shown) such as a motor is connected to the base 4. When this rotary drive source is operated, the chuck table 6 can be rotated about a rotation axis perpendicular to the upper surface.

[0047] The liquid resin supply nozzle 14 has an outlet positioned above the center of the upper surface of the chuck stage 6, and supplies liquid resin 16 to the first surface 1a of the wafer 1 held by the chuck stage 6. The liquid resin 16 supplied to the wafer 1 from the liquid resin supply nozzle 14 can be a material that is water-soluble and will solidify when dried in air. For example, polyvinyl alcohol, polyvinylpyrrolidone, or the "HOGOMAX (registered trademark)" series manufactured by DISCO Corporation can be used as the liquid resin 16. However, the liquid resin 16 is not limited to these.

[0048] In the protective film formation step S10, the frame unit 13 is moved into the spin coater 2 and placed on the chuck stage 6, and the frame 11 is held by the clamp 8 and the wafer 1 is held by the chuck stage 6. Then, the liquid resin supply nozzle 14 is positioned above the center of the wafer 1, and while the spin drive source is operated to make the chuck stage 6 rotate at high speed around the rotation axis, liquid resin 16 is dripped from the liquid resin supply nozzle 14 onto the first surface 1a of the wafer 1.

[0049] In this way, wafer 1 is spin-coated, and the first surface 1a is covered by liquid resin 16. Thereafter, if wafer 1 is left in the atmosphere for a period of 10 minutes to 30 minutes to cure the liquid resin 16, a protective film 15 is formed on the first surface 1a of wafer 1 (see FIG3, etc.). FIG4(A) is an enlarged and schematic cross-sectional view of wafer 1 with the protective film 15 formed.

[0050] One of the functions of the protective film 15 is, as described later, to prevent molten material, referred to as debris, that is scattered during the ablation process of wafer 1 from re-adhering to the first surface 1a of wafer 1. During the ablation process of wafer 1, debris adheres to the upper surface of the protective film 15. Then, when the protective film 15 is removed from wafer 1, the debris is also removed from wafer 1. Therefore, the first surface 1a of wafer 1 is not contaminated by debris.

[0051] Here, if the only goal is to prevent debris from re-adhering to wafer 1, a thickness of about 1 μm for the protective film 15 is sufficient. However, in the protective film formation step S10, it is desirable to have a thicker protective film 15 on wafer 1. For example, the thickness of the protective film 15 is preferably 5 μm or more, and more preferably 7 μm or more and 30 μm or less. If a thick protective film 15 is provided on wafer 1 having resin layer 7, then, as will be described later, the expansion of the hardened area of ​​resin layer 7 can be reduced during the ablation process of wafer 1.

[0052] This is believed to be because when high-temperature debris generated during the ablation process adheres to the surface of the protective film 15, heat transfer from the debris to the resin layer 7 through the protective film 15 is reduced. Alternatively, it is believed to be because the thick protective film 15 makes it easier for the high-temperature debris to be guided and discharged upwards. Alternatively, it is believed to be because the thick protective film 15 promotes heat dissipation and reduces the impact of heat on the resin layer 7. In any case, the thick protective film 15 functions to reduce the expansion of the hardened area of ​​the resin layer 7.

[0053] In order to form a thick protective film 15 on the wafer 1 having the resin layer 7, repeated spin coating can be considered. That is, a first spin coating is performed, in which liquid resin 16 is coated on the first surface 1a of the wafer 1 and dried to form a first layer of the protective film 15, and then a second spin coating is performed, in which liquid resin 16 is coated on the first layer and dried to form a second layer of the protective film 15. If spin coating is repeated in this way, a thick protective film 15 can be formed on the first surface 1a of the wafer 1.

[0054] In the case of forming a thick protective film 15 by performing multiple spin coatings, in order to form a protective film 15 with good surface flatness in a short time, the film formation conditions can be changed at each stage of spin coating. For example, the rotation speed of the chuck stage 6 can be reduced in the initial spin coating to form a thick layer, and the rotation speed of the chuck stage 6 can be increased in the final spin coating to form a layer with good surface flatness.

[0055] After the protective film formation step S10, a processing trench formation step S20 is performed, in which a first laser beam of an absorptive wavelength (a wavelength that absorptive to the wafer 1) is irradiated onto the wafer 1 from the first surface 1a side along the predetermined processing line 3 to form a processing trench. Figure 3 is a schematic cross-sectional view of the processing trench formation step S20.

[0056] The processing tank forming step S20 is performed, for example, by the laser processing apparatus 18 shown in FIG3. The laser processing apparatus 18 includes: a chuck stage 6a, which attracts and holds the wafer 1; and a laser processing unit 20, which irradiates the wafer 1 held by the chuck stage 6a with a first laser beam 22.

[0057] The chuck table 6a has a frame 10a and a porous member 12a housed in the frame 10a, and is supported by a base 4a. Furthermore, a clamp 8a for holding the frame unit 13 is arranged around the chuck table 6a. Since the structure and construction of the chuck table 6a are the same as those of the chuck table 6 of the rotary coating machine 2, detailed descriptions are omitted.

[0058] The laser processing unit 20 includes: a laser oscillator (not shown) that can oscillate a laser beam of a wavelength that will be absorbed by the wafer 1; and an optical system (not shown) that guides the laser beam emitted from the laser oscillator and focuses it onto the wafer 1. For example, in the case where the wafer 1 is a silicon wafer, the laser processing unit 20 can irradiate the wafer 1 with a laser beam of wavelength 355 nm.

[0059] The laser processing apparatus 18 includes: a processing feed unit that can move the chuck table 6a and the laser processing unit 20 relative to each other in the processing feed direction; and an indexing feed unit that can move the chuck table 6a and the laser processing unit 20 relative to each other in an indexing feed direction orthogonal to the processing feed direction.

[0060] When dicing wafer 1, firstly, frame unit 13 is placed on chuck stage 6a and held by chuck stage 6a. Then, chuck stage 6a is rotated so that the direction of the machining predetermined line 3 of wafer 1 is aligned with the machining feed direction.

[0061] Then, while operating the processing feed unit to move the chuck stage 6a and the laser processing unit 20 relative to each other in the processing feed direction, the laser processing unit 20 is operated to irradiate the predetermined processing line 3 of the wafer 1 with a first laser beam 22. In this way, a processing groove 17 is formed on the wafer 1 along the predetermined processing line 3 by ablation. At this time, the debris generated and scattered from the wafer 1 will adhere to the protective film 15, so there will be no debris adhering to the first surface 1a side of the wafer 1.

[0062] The irradiation conditions of the first laser beam 22 in the machining tank forming step S20 are set as follows, for example. However, the irradiation conditions of the first laser beam 22 are not limited thereto. Wavelength: 355nm Repetition frequency: 300kHz Average output: 7W Feed rate: 1000mm / second

[0063] After performing ablation along one predetermined processing line 3, the chuck stage 6a and the laser processing unit 20 are moved relative to each other in an indexing feed direction perpendicular to the processing feed direction, and the wafer 1 is similarly ablated along other predetermined processing lines 3. After forming the processing groove 17 along all the predetermined processing lines 3 in one direction, the chuck stage 6a is rotated about an axis perpendicular to the holding surface, and the wafer 1 is similarly ablated along the predetermined processing lines 3 in another direction.

[0064] For example, if the processing trench 17 formed along all the predetermined processing lines 3 of the wafer 1 extends from the first side (front side) 1a to the second side (back side) 1b, the wafer 1 will be divided into individual wafers. However, the processing trench 17 is not limited to this, and the processing trench 17 may not reach the second side 1b of the wafer 1. In this case, the wafer 1 can be broken from the bottom of the processing trench 17 to the second side 1b by other additional processing.

[0065] Furthermore, when the processing groove 17 has not reached the second surface 1b of the wafer 1, at this point in time, the regions of the wafer 1 have not been cut and separated from each other, and therefore there is no situation where the positions of the regions are offset from each other. In this case, as will be described later, in the hardened region removal step S30, the regions that become the targets of irradiation when the second laser beam 24 is irradiated toward the wafer 1 are fixed together, so it is easy to irradiate the desired location of the wafer 1 with the second laser beam 24 without deviation. That is, the processing accuracy performed by the second laser beam 24 is improved.

[0066] Therefore, the necessity of inspecting the processing status of wafer 1 during processing is reduced, and the number of inspections can be reduced to quickly end the processing of wafer 1. That is, the situation where the processing groove 17 does not reach the second side 1b of wafer 1 is related to the improvement of wafer manufacturing efficiency. In addition, in this case, wafer 1 will eventually be divided along the processing groove 17 by applying external force to wafer 1. However, the processing groove forming step S20 is not limited to this, and the processing groove 17 can also reach the second side 1b.

[0067] Furthermore, in cases where the processing groove 17 does not reach the second surface 1b of the wafer 1, the external force applied to divide the wafer 1 is, for example, applied to the wafer 1 by expanding the adhesive film 9 radially outward within the opening of the frame 11. If the adhesive film 9 is expanded radially outward, a radially outward force is applied to the wafer 1 adhered to the adhesive film 9, causing a crack at the bottom of the processing groove 17 and dividing the wafer 1. The manner in which this crack is generated determines the height position of the bottom of the processing groove 17.

[0068] Alternatively, the external force applied to cleave wafer 1 can be applied to wafer 1 by pushing wafer 1 from above with a roller longer than the diameter of wafer 1 while rotating the roller on the first surface 1a of wafer 1. Alternatively, the external force can also be applied to wafer 1 by pushing the back side of the adhesive film 9 of frame unit 13 from below while rotating the roller on the back side of adhesive film 9.

[0069] Furthermore, the external force applied to cleave wafer 1 can also be applied to wafer 1 by further irradiation with a laser beam. That is, a laser beam is irradiated to the bottom of the processing tank 17 from the first surface 1a side of wafer 1, and wafer 1 is laser-processed below the processing tank 17. In this way, a cleaving groove reaching the second surface 1b side of wafer 1 can be formed to cleave wafer 1. In addition, since the irradiated area of ​​the laser beam is far away from the resin layer 7, the resin layer 7 is less likely to undergo the deterioration and hardening caused by the irradiation of the laser beam, as described later.

[0070] Here, in the processing trench forming step S20, the first laser beam 22 can also be split into one or both directions parallel to the processing predetermined line 3 of the wafer 1 (processing feed direction) and perpendicular to it (indexing feed direction) to irradiate the wafer 1. In this case, since the split first laser beam 22 is irradiated to each processing point one by one, the load applied to the wafer 1 is smaller than that when the unsplit, powerful first laser beam 22 is irradiated to each processing point. Furthermore, each processing point will not be overheated.

[0071] However, when the first laser beam 22 is split and irradiated onto the wafer 1, the wafer 1 is also heated by the first laser beam 22, and therefore the resin layer 7 around the processing groove 17 deteriorates and hardens. Figure 4(B) is an enlarged and schematic cross-sectional view of the wafer 1 with the processing groove 17 formed. In Figure 4(B), the hardened region 7a of the resin layer 7 and the deteriorated region 15a of the protective film 15 are schematically shown.

[0072] After the processing tank forming step S20, a hardened area removal step S30 is performed, which removes the hardened area 7a of the hardened resin layer 7. FIG5 is a schematic cross-sectional view of the hardened area removal step S30. In FIG5, the hardened area 7a and the like are omitted. The hardened area removal step S30 can be performed after the processing tank forming step S20 by means of the laser processing apparatus 18. However, the hardened area removal step S30 is not limited to this and can also be performed by other laser processing apparatuses.

[0073] In the hardened region removal step S30, for example, the hardened region 7a containing the resin layer 7 is irradiated with a second laser beam 24 under conditions lower than the threshold at which the resin layer 7 will harden. The irradiation conditions of the second laser beam 24 are determined in such a way that the energy density becomes lower than that of the first laser beam 22, but the second laser beam 24 can also be irradiated onto the wafer 1 in the same way as the first laser beam 22 in the processing tank formation step S20.

[0074] Furthermore, the irradiation conditions of the second laser beam 24 in the hardened region removal step S30 are set as follows, for example. However, the irradiation conditions of the second laser beam 24 are not limited thereto. Wavelength: 355nm; Repetition rate: 300kHz; Average output: 6W; Feed rate: 1000mm / second

[0075] Herein, in the hardened area removal step S30, the second laser beam 24 can be irradiated in one or both of the directions parallel to the processing predetermined line 3 of the wafer 1 (processing feed direction) and perpendicular to it (indexing feed direction). Furthermore, in the hardened area removal step S30, the second laser beam 24 can be shaped into an ellipse with different lengths of its major and minor axes, a rectangle with different lengths of its long and short sides, or a square with equal lengths of its four sides before irradiating the wafer 1.

[0076] Furthermore, the second laser beam 24 can be directed onto the wafer 1 with the major axis of the elliptical second laser beam 24, the long side of the rectangular second laser beam 24, or one side of the square second laser beam 24 oriented perpendicular to the predetermined processing line 3. Additionally, the second laser beam 24 can be directed either parallel to or perpendicular to the predetermined processing line 3 of the wafer 1.

[0077] Figure 6(A) is a schematic perspective view of the branching components 26 of a branched second laser beam 24 in one example. Furthermore, in Figure 6(A), the branching components 26 are shown in solid lines for ease of explanation. In the example shown in Figure 6(A), the second laser beam 24 branches in a direction parallel to the processing predetermined line 3 (the X-axis direction in Figure 6(A)). Then, each branching component 26 of the second laser beam 24 is shaped into a rectangle, with its longer side 28, which is longer than its shorter side 30, oriented in a direction perpendicular to the processing predetermined line 3 (the Y-axis direction in Figure 6(A)).

[0078] For example, in the hardened region removal step S30, a second laser beam 24 with a width wider than the processing trench 17 formed on the wafer 1 in the processing trench formation step S20 can be irradiated onto the wafer 1. That is, the long side 28 of each branch component 26 of the rectangle of the second laser beam 24 is preferably longer than the width of the processing trench 17. Alternatively, the long axis of each branch component of the ellipse of the second laser beam 24 is preferably longer than the width of the processing trench 17.

[0079] Then, the second laser beam 24 is preferably irradiated onto the wafer 1 in such a manner that the two hardened regions 7a of the resin layer 7 formed on both sides of the processing tank 17 are contained between one end and the other end of the long side 28. That is, the long side 28 is preferably set to a length greater than the distance between the outer edge of the hardened region 7a formed on one side of the processing tank 17 and the outer edge of the hardened region 7a formed on the other side of the processing tank 17.

[0080] In this case, if the second laser beam 24 is irradiated along the processing groove 17 onto the hardened regions 7a on both sides of the processing groove 17, the hardened regions 7a can be removed. Figure 8(A) is an enlarged and schematic cross-sectional view of the wafer 1 with the hardened regions 7a of the resin layer 7 removed. Here, in a manner that reliably removes the hardened regions 7a, the second laser beam 24 can be irradiated onto the unhardened regions of the resin layer 7 adjacent to the hardened regions 7a, and the unhardened regions can be partially removed by the second laser beam 24.

[0081] Hereinafter, other differences in the irradiation conditions between the first laser beam 22 irradiated to the wafer 1 in the processing tank forming step S20 and the second laser beam 24 irradiated to the wafer 1 in the hardening region removal step S30 will be explained.

[0082] For example, the first laser beam 22 is preferably a Gaussian beam with a Gaussian intensity distribution in the irradiated area. The Gaussian beam has a high intensity at the center of the irradiated area, which can be used to form a deep processing groove 17. On the other hand, the second laser beam 24 is preferably a flat-top beam with a more uniform intensity distribution in the irradiated area. The flat-top beam has a wide tolerance for deviations in the irradiation position and can easily and reliably remove the hardened area 7a from the uppermost to the lowermost point.

[0083] The laser processing unit 20 is preferably equipped with a beam shaper (laser beam shaping element) that converts a Gaussian beam into a flat-top beam, through which the second laser beam 24 can be irradiated onto the wafer 1. The beam shaper is, for example, a DoE (Diffractive Optical Element) or a homogenizer.

[0084] Furthermore, the width of the hardened region 7a formed in the processing tank forming step S20 varies depending on the irradiation conditions of the first laser beam 22 or the material and thickness of the wafer 1, resin layer 7, and protective film 15. Therefore, after performing the processing tank forming step S20, the width of the hardened region 7a can be obtained by observing the wafer 1, and the length of the long side 28 of the second laser beam 24 can be determined based on the obtained information.

[0085] Furthermore, if the irradiation conditions of the first laser beam 22, or the materials and thicknesses of the wafer 1, resin layer 7, and protective film 15, are fixed, the width of the hardened region 7a also becomes approximately fixed. Therefore, when the same wafer 1 is repeatedly processed under the same processing conditions to manufacture a wafer, it is not necessary to observe the wafer 1 each time to determine the length of the long side 28 of the second laser beam 24. In the hardened region removal step S30, the wafer 1 can be irradiated by the second laser beam 24, which has been shaped to a predetermined length with the long side 28 extending outwards.

[0086] Furthermore, Figure 6(B) is a perspective view schematically showing the branching components 32 of the branched second laser beam 24 in another example. In addition, in Figure 6(B), the branching components 32 are shown in solid lines for ease of explanation. The branching components 32 of the second laser beam 24 are shaped into rectangles, with the longer side 37, which is longer than its shorter side, facing a direction perpendicular to the processing predetermined line 3.

[0087] Furthermore, in the example shown in FIG6(B), the second laser beam 24 splits into multiple beams in a direction parallel to the processing predetermined line 3 (X-axis direction in FIG6(B)) and into two beams in a direction perpendicular to the processing predetermined line 3 (Y-axis direction in FIG6(B)).

[0088] The interval 36 of each branching component 32 that branches into two in the vertical direction of the pre-processed line 3 may be, for example, less than the width of the processing trench 17 formed on the wafer 1. Then, the long side 37 of each branching component 32 of the rectangle of the second laser beam 24 is preferably longer than the width of each of the hardened regions 7a formed on both sides of the processing trench 17.

[0089] In the hardened region removal step S30, each hardened region 7a of the resin layer 7 formed on both sides of the processing tank 17 formed on the wafer 1 during the processing tank formation step S20 can be irradiated with a second laser beam 24 that has been split into two beams. More specifically, one of the hardened regions 7a can be irradiated with the first beam of the second laser beam 24 that has been split into two beams, and the other hardened region 7a on the opposite side of the processing tank 17 can be irradiated with the second beam of the second laser beam 24.

[0090] In the wafer manufacturing method of this embodiment, debris or processing shavings are generated during the processing trench formation step S20 and the hardening region removal step S30. These debris fly towards the first surface 1a of the wafer 1 and adhere to the protective film 15. Therefore, after the hardening region removal step S30, a protective film removal step S40 is performed to remove the protective film 15 formed on the first surface 1a of the wafer 1, and the debris, processing shavings, and protective film 15 are removed from the wafer 1 together.

[0091] Figure 7 is a schematic cross-sectional view of the protective film removal step S40. The protective film removal step S40 can be performed by a cleaning device 38 that supplies cleaning water 42 to the frame unit 13 containing the wafer 1. The cleaning device 38 includes: a chuck stage 6b that attracts and holds the wafer 1 through the adhesive film; and a cleaning water supply nozzle 40 that supplies cleaning water 42 to the wafer 1 held by the chuck stage 6b.

[0092] The chuck stage 6b has a frame 10b and a porous member 12b housed in the frame 10b, and is supported by a base 4b. Furthermore, a clamp 8b for holding the frame unit 13 is provided around the chuck stage 6b.

[0093] A rotary drive source, such as a motor (not shown), is connected to the base 4b. When this rotary drive source is operated, the chuck table 6b can be rotated around a rotation axis perpendicular to the upper surface. Furthermore, since the structure and construction of the chuck table 6b are the same as those of the chuck table 6 of the rotary coating machine 2, detailed descriptions are omitted.

[0094] The cleaning water supply nozzle 40 has a discharge port that can move back and forth on a track above the center of the upper surface of the chuck stage 6b, and supplies cleaning water 42, such as pure water, to the first surface 1a of the wafer 1 held by the chuck stage 6b for cleaning. In addition, high-pressure gas can be mixed into the cleaning water 42 supplied to the wafer 1 from the cleaning water supply nozzle 40, so that the wafer 1 can be cleaned by the mixed fluid of pure water and high-pressure gas.

[0095] In the protective film removal step S40, the frame unit 13 is moved into the cleaning apparatus 38 and placed on the chuck stage 6b. The frame 11 is held by the clamp 8b, and the wafer 1 is held by the chuck stage 6b through the adhesive film 9. Then, while the outlet of the cleaning water supply nozzle 40 moves back and forth on a predetermined track, the rotary drive source is operated to rotate the chuck stage 6b around the rotation axis at high speed. Then, cleaning water is sprayed from the cleaning water supply nozzle 40 onto the first surface 1a of the wafer 1.

[0096] In this way, the first surface 1a of the wafer 1 is cleaned with cleaning water 42. Then, the water-soluble resin, i.e., the protective film 15, is removed by the cleaning water 42, as well as debris, processing chips, etc. Afterward, the cleaning water 42 from the cleaning water supply nozzle 40 is stopped from spraying out, and the wafer 1 is dried. Figure 8(B) is a schematic cross-sectional view of the wafer 1 after the protective film 15 has been removed. If the wafer 1 is cut by the processing tank 17, multiple wafers with resin layers 7 on their upper surfaces can be obtained.

[0097] As described above, in the wafer manufacturing method of this embodiment, a protective film 15 is formed on the first surface 1a of a wafer 1 having a resin layer 7, and the wafer 1 is irradiated with a first laser beam 22 to cleave the wafer 1. At this time, although a hardened region 7a is formed in the resin layer 7, this hardened region 7a is subsequently removed, and the protective film 15 is removed from the first surface 1a.

[0098] Therefore, the wafer obtained by dicing wafer 1 does not retain the hardened region 7a of the resin layer 7 hardened by the first laser beam 22. Therefore, when multiple wafers are laminated and thermally bonded, the resin layer 7 extends appropriately and no air bubbles remain inside. Therefore, the laminated wafers do not have wafer defects caused by the hardened region 7a.

[0099] Furthermore, the present invention is not limited to the descriptions of the above embodiments and can be modified and implemented in various ways. For example, in the above embodiments, although the hardened region removal step S30 describes removing the hardened region 7a by irradiating the hardened region 7a of the resin layer 7 with the second laser beam 24, the present invention is not limited to this. That is, in the hardened region removal step S30, the hardened region 7a of the resin layer 7 can also be removed from the wafer 1 by other methods. Next, a modified example of the hardened region removal step S30 will be described.

[0100] FIG9 is a schematic cross-sectional view of the hardened region removal step S30 of the modified example. In the hardened region removal step S30 of the modified example, the hardened region 7a of the resin layer 7 is removed by cutting it with an annular cutting blade 50. The cutting of the hardened region 7a is performed by the cutting apparatus 44 shown in FIG9. The cutting apparatus 44 includes: a chuck stage 6c, which holds the wafer 1; and a cutting unit 46, which cuts the wafer 1 held by the chuck stage 6c.

[0101] The chuck table 6c has a frame 10c and a porous member 12c housed in the frame 10c, and is supported by a base 4c. Furthermore, a clamp 8c for holding the frame unit 13 is provided around the chuck table 6c. Since the structure and configuration of the chuck table 6c are the same as those of the chuck table 6 of the rotary coating machine 2, detailed descriptions are omitted.

[0102] The cutting device 44 includes: a processing feed unit that can move the chuck table 6c and the cutting unit 46 relative to each other in the processing feed direction; and an indexing feed unit that can move the chuck table 6c and the cutting unit 46 relative to each other in an indexing feed direction orthogonal to the processing feed direction.

[0103] The cutting unit 46 of the cutting device 44 includes: a main shaft 48 along the indexing feed direction; and a cutting blade 50 fixed to the front end of the main shaft 48. A rotary drive source such as a motor is connected to the base end of the main shaft 48. When the rotary drive source is operated, the cutting blade 50 rotates about the main shaft 48 as an axis.

[0104] The cutting blade 50 includes: an annular base 52, which is formed of a metal material such as aluminum; and an annular abrasive portion 54, which is fixed to the outer periphery of the base 52. The abrasive portion 54 is constructed by means of abrasive grains formed of diamond or the like and a bonding material that disperses and fixes the abrasive grains. When the cutting blade 50 is rotated and the abrasive portion 54 contacts the workpiece, the workpiece is cut.

[0105] Herein, the cutting blade thickness (thickness of the grinding stone portion 54) of the cutting blade 50 mounted at the front end of the spindle 48 is preferably greater than the width of the processing groove 17 formed on the wafer 1 in the processing groove forming step S20. Furthermore, the cutting blade is preferably designed to cut the entire area of ​​the hardened region 7a of the resin layer 7 formed on both sides of the processing groove 17, and its cutting blade thickness is greater than the distance between the outer edge of the hardened region 7a on one side of the processing groove 17 and the outer edge of the hardened region 7a on the other side.

[0106] When cutting the hardened region 7a, firstly, the frame unit 13 is placed on the chuck stage 6c, and the frame unit 13 is held by the chuck stage 6c. Then, the chuck stage 6c is rotated so that the direction of the processing predetermined line 3 of the wafer 1 is aligned with the processing feed direction.

[0107] Then, the abrasive portion 54 of the cutting blade 50 is positioned above the extension line of the processing groove 17 formed on the wafer 1, and the cutting blade 50 is rotated at a predetermined speed. Then, the cutting unit 46 is lowered such that the lower end of the abrasive portion 54 is positioned at the height of the lower end of the resin layer 7. Thereafter, the processing feed unit is operated, and the chuck stage 6c and the cutting unit 46 move relative to each other in the processing feed direction, and the cutting blade 50 cuts into the hardened region 7a of the resin layer 7, thereby removing the hardened region 7a.

[0108] After cutting the hardened region 7a along one predetermined processing line 3, the chuck stage 6c and the cutting unit 46 are moved in the indexing feed direction, and the hardened regions 7a of the resin layer 7 are cut along other predetermined processing lines 3 in the same way. After removing the hardened region 7a along all the predetermined processing lines 3 in one direction, the chuck stage 6c is rotated, and the hardened region 7a is cut along the predetermined processing lines 3 in another direction in the same way. In this way, all the hardened regions 7a of the resin layer 7 of the wafer 1 can be removed.

[0109] Furthermore, in the case where the hardened area removal step S30 is performed by cutting with the cutting blade 50, the hardened areas 7a of the resin layer 7 formed on both sides of the processing groove 17 can also be removed individually. In this case, the cutting thickness of the cutting blade 50 is preferably greater than the width of each hardened area 7a formed on both sides of the processing groove 17. In this way, the hardened area removal step S30 can also be performed by cutting with the cutting blade 50.

[0110] Furthermore, although the above embodiment describes a resin layer 7 that functions as an NCF being provided on the first surface 1a side of the wafer 1, and the hardened region 7a formed on the resin layer 7 being removed, the present invention is not limited to this. That is, the resin layer 7 provided on the first surface 1a side of the wafer 1 may not be an NCF.

[0111] For example, on the first surface 1a of wafer 1, there may be a resin layer 7 provided for other purposes. Then, when wafer 1 is diced and formed into a wafer by ablation, the resin layer 7 may be partially heated and deteriorated, and deteriorated areas may form in the resin layer 7 remaining on the wafer. For example, due to the heat caused by the ablation process, the resin layer 7 may partially discolor, and the appearance of the wafer formed by dicing wafer 1 may deteriorate.

[0112] Therefore, the deteriorated region of the resin layer 7 can also be removed by the second laser beam 24, etc. That is, the deteriorated region of the resin layer 7 is removed by the above-described steps as the hardening region removal step S30. In this case, the hardening region removal step S30 can be renamed the deteriorated region removal step, and the hardening region 7a of the resin layer 7 can be renamed the deteriorated region.

[0113] Furthermore, although the above embodiment describes the case where the element 5 is formed on the first surface 1a of the wafer 1 where the resin layer 7 is disposed, the present invention is not limited to this. That is, the element 5 can also be disposed on the second surface 1b. In this case, the first surface 1a of the wafer 1 is referred to as the back surface, and the second surface 1b is referred to as the front surface. In this case, the hardened region 7a formed on the resin layer 7 when the wafer 1 is irradiated with the first laser beam 22 from the first surface 1a side can also be removed by the hardened region removal step S30.

[0114] That is, the wafer manufacturing method of the present invention can be widely applied to any wafer manufacturing method including the following process: a process of dividing a wafer 1 on the side irradiated by a laser beam during ablation by means of an ablation process.

[0115] In addition, the structure and method of the above embodiments can be appropriately modified and implemented as long as they do not depart from the scope of the present invention. [Simplified Explanation of the Diagram]

[0025] Figure 1 is a schematic perspective view of a wafer having a resin layer on its first surface. Figure 2 is a schematic cross-sectional view of the protective film formation step. Figure 3 is a schematic cross-sectional view of the processing groove formation step. Figure 4(A) is an enlarged and schematic cross-sectional view of a wafer with a protective film disposed thereon, and Figure 4(B) is an enlarged and schematic cross-sectional view of a wafer with a processing groove formed thereon. Figure 5 is a schematic cross-sectional view of the hardened area removal step. Figure 6(A) is a schematic perspective view of laser beams branching in a direction parallel to the predetermined processing line, and Figure 6(B) is a schematic perspective view of laser beams branching in directions parallel to and perpendicular to the predetermined processing line. Figure 7 is a schematic cross-sectional view of the protective film removal step. Figure 8(A) is an enlarged and schematic cross-sectional view of a wafer with the hardened area where the resin layer has been removed, and Figure 8(B) is an enlarged and schematic cross-sectional view of a wafer with the protective film removed. Figure 9 is a cross-sectional view schematically illustrating a modified example of the hardened region removal step. Figure 10 is a flowchart illustrating the steps of the wafer manufacturing method.

Claims

1. A method for manufacturing a wafer, comprising dicing a wafer having a resin layer on a first side along a predetermined processing line to manufacture a wafer, characterized in that it includes: a protective film forming step, wherein a protective film is formed on the first side; a processing trench forming step, wherein, after the protective film forming step, a first laser beam of an absorptive wavelength is irradiated onto the wafer from the first side along the predetermined processing line to form a processing trench on the wafer; a hardened region removal step, wherein, after the processing trench forming step, a hardened region of the hardened resin layer is removed; and a protective film removal step, wherein, after the hardened region removal step, the protective film formed on the first side is removed, wherein, in the hardened region removal step, the hardened region containing the resin layer is irradiated with a second laser beam to remove the hardened region, and wafers are formed by dicing the wafer along the processing trench.

2. A method for manufacturing the chip as described in claim 1, wherein, The energy density of the second laser beam is lower than that of the first laser beam.

3. A method for manufacturing the wafer as described in claim 1 or 2, wherein, The first laser beam is a Gaussian beam, and the second laser beam is a top-hat beam.

4. A method for manufacturing the wafer as described in claim 1 or 2, wherein, In the hardened area removal step, the wafer is irradiated with a second laser beam that is wider than the width of the processing groove.

5. A method for manufacturing the wafer as described in claim 1 or 2, wherein, In the hardened area removal step, the second laser beam is shaped into an ellipse with different lengths of its major and minor axes, a rectangle with different lengths of its long and short sides, or a square with equal lengths of its four sides. The wafer is then irradiated with the second laser beam with its major axis, long side, or one of the sides oriented in a direction perpendicular to the predetermined processing line.

6. A method for manufacturing the wafer as described in claim 1 or 2, wherein, In the hardened area removal step, the second laser beam is irradiated in one or both of a direction parallel to and perpendicular to the predetermined processing line of the wafer.

7. A method for manufacturing the wafer as described in claim 1 or 2, wherein, In the hardened region removal step, the region containing the resin layer is irradiated with the second laser beam at a condition less than the threshold at which the resin layer would harden.

8. A method for manufacturing the wafer as described in claim 1, wherein, In the process of forming the processing groove, a first laser beam is irradiated onto the wafer by splitting into one or both directions parallel to and perpendicular to the predetermined processing line of the wafer.

9. A method for manufacturing the wafer as described in claim 1, wherein, The resin layer is NCF.

10. A method for manufacturing the wafer as described in claim 1, wherein, The thickness of the protective film is 5 μm or more.

11. A method for manufacturing the wafer as described in claim 1, wherein, The processing groove formed in the processing groove formation step does not reach the second side of the wafer that is parallel to the first side. The wafer is divided along the processing groove by applying an external force to the wafer.

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