Coating Method

Abstract

To remove air bubbles from a liquid resin before being spread after having been coated.SOLUTION: A coating method for coating a surface side of a wafer with a solid resin includes a holding step of holding a rear face side of the wafer positioned on a side opposite to the surface with a holding table, a coating step of coating a liquid resin to the surface side of the wafer or a plate-like object after the holding step, a heating step of heating the liquid resin after the coating step, and a pressing step of pressing at least one of the plate-like object and the wafer and bonding the plate-like object and the wafer through the liquid resin, after the heating step, and bursts air bubbles contained in the liquid resin by the heating step.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a coating method for covering the front surface side of a wafer with a resin. [Background technology]

[0002] When grinding the back side of a wafer on which a plurality of devices are formed on the front side and on which a plurality of bumps are formed in contact with each device, it is known to form a resin layer thick enough to absorb the surface-side unevenness in order to prevent the surface-side unevenness caused by the bumps, etc. from being transferred to the back side and to reduce in-plane thickness variations (see, for example, Patent Document 1).

[0003] Specifically, a liquid UV (ultraviolet) curable resin is supplied to the front side of the wafer, and then the liquid resin is cured by UV irradiation, so that the front side of the wafer is covered with a solid resin layer having a substantially flat outer surface.

[0004] However, when the front side of the wafer is covered with liquid resin, air bubbles are mixed in. If the liquid resin containing air bubbles is cured, bumps, devices, etc. located near the air bubbles may not be adequately protected by the resin layer and may be damaged due to the pressure and impact applied to the wafer during grinding.

[0005] One proposed mechanism for the introduction of air bubbles into the liquid resin is that when the liquid resin is pushed and spread toward the surface of the wafer, the flowing resin separates into two regions, upper and lower, generating air bubbles, which are then trapped in the liquid resin (see, for example, Patent Document 2).

[0006] Therefore, Patent Document 2 proposes a method for preventing air bubbles from being trapped in the liquid resin when the liquid resin is spread out by maintaining the front side of the wafer in contact with a liquid resin applied in a dome shape on a table, and by bringing the wafer closer to the table while repeatedly moving the wafer closer and further away from the table. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2017-50536 [Patent Document 2] Japanese Patent Application Publication No. 2018-67586 Summary of the Invention [Problem to be solved by the invention]

[0008] However, when the liquid resin is applied onto the table or wafer, it may already contain air bubbles. The present invention has been made in consideration of this problem, and has an object to remove air bubbles from the liquid resin after it has been applied but before it is spread. [Means for solving the problem]

[0009] According to one aspect of the present invention, there is provided a coating method for covering the front side of a wafer with a solid resin, the coating method comprising: a holding step of holding the back side of the wafer, which is located opposite to the front side, on a holding table; an application step of applying liquid resin to the front side of the wafer or to a plate-like object after the holding step; a heating step of heating the liquid resin after the application step; and a pressing step of pressing at least one of the plate-like object and the wafer to bond the plate-like object and the wafer together via the liquid resin after the heating step, wherein air bubbles contained in the liquid resin are burst by the heating step.

[0010] Preferably, in the heating step, the liquid resin is heated by jetting hot air.

[0011] According to another aspect of the present invention, there is provided a coating method for covering the front side of a wafer with a solid resin, the coating method comprising: a holding step of holding the back side of the wafer opposite the front side with a holding table; an application step of applying liquid resin to the front side of the wafer or to a plate-like object after the holding step; an ultrasonic application step of applying ultrasonic waves to the liquid resin after the application step; and a pressing step of pressing at least one of the plate-like object and the wafer to bond the plate-like object and the wafer together via the liquid resin after the ultrasonic application step, wherein air bubbles contained in the liquid resin are burst by the ultrasonic application step.

[0012] Preferably, the liquid resin is a UV-curable resin, the plate-shaped object is a transparent substrate that is transparent to UV, and the coating method further includes a UV irradiation step of irradiating the UV-curable resin with UV through the plate-shaped object after the pressing step.

[0013] Preferably, the liquid resin is a thermosetting resin, and the coating method further comprises, after the pressing step, a heat curing step of heating and curing the thermosetting resin. Preferably, in the applying step, the liquid resin is applied to only one of the front surface side of the wafer or the plate-like object. [Effects of the Invention]

[0014] In the coating method according to one aspect of the present invention, even if air bubbles are mixed in the liquid resin when the liquid resin is applied, the air bubbles can be removed from the liquid resin by bursting the air bubbles. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a flow diagram of a coating method. [Figure 2] FIG. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] 3 is a schematic diagram showing a liquid resin after a heating step. FIG. [Figure 6] FIG. [Figure 7] FIG. 1 shows a UV irradiation step. [Figure 8] FIG. 8(A) is a photograph of the liquid resin taken from above before the heating step, and FIG. 8(B) is a photograph of the liquid resin taken from above after the heating step. [Figure 9] FIG. 10 is a diagram showing a holding step according to the second embodiment. [Figure 10] FIG. 10 is a diagram showing a coating step according to the second embodiment. [Figure 11] FIG. 10 is a diagram showing a heating step according to the second embodiment. [Figure 12] FIG. 10 is a schematic diagram showing a liquid resin and the like after a heating step according to the second embodiment. [Figure 13] FIG. 10 is a diagram showing a pressing step according to the second embodiment. [Figure 14] FIG. 10 is a diagram showing a UV irradiation step according to the second embodiment. [Figure 15] FIG. 10 is a flow diagram of a coating method according to a third embodiment. [Figure 16] FIG. 10 is a diagram showing a heat curing step according to a third embodiment. [Figure 17] FIG. 10 is a flow diagram of a coating method according to a fourth embodiment. [Figure 18] FIG. 10 is a diagram showing an ultrasonic wave applying step according to the fourth embodiment. [Figure 19] FIG. 11 is a diagram showing an ultrasonic wave applying step according to the fifth embodiment. [Figure 20] FIG. 10 is a flow diagram of a coating method according to a sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] An embodiment according to one aspect of the present invention will be described with reference to the accompanying drawings. In this embodiment, the steps shown in FIG. 1 are carried out to cover the front surface 11a of the wafer 11 (see FIG. 2) with a hardened solid resin layer (solid resin) 25 (see FIG. 7).

[0017] FIG. 1 is a flow diagram of the coating method according to the first embodiment, in which a holding step S10, a coating step S20, a heating step S30, a pressing step S40, and a UV irradiation step S50 are carried out in this order.

[0018] 2 to 7, a processing device 2 used when covering the front surface 11a side with a resin layer 25 will be described. As shown in Fig. 2, the processing device 2 has a disk-shaped chuck table (holding table) 4. The chuck table 4 has a metal frame having a diameter larger than that of the wafer 11.

[0019] A disk-shaped recess (not shown) is formed on the top surface of the frame, and a disk-shaped porous plate (not shown) made of porous ceramics is fixed in this recess. A plurality of grooves (not shown) are formed radially at the bottom of the recess.

[0020] Each groove in the frame is connected to a through-hole (not shown) formed in the frame so as to penetrate the center of the frame in the radial direction. A suction source (not shown), such as an ejector, is connected to this through-hole. Negative pressure generated by the suction source is transmitted to the upper surface of the porous plate via the frame.

[0021] The upper surface of the frame and the upper surface of the porous plate are formed to be substantially flush with each other, and function as a holding surface 4a that suction-holds the wafer 11. The holding surface 4a suction-holds the back surface 11b of the wafer 11, which is located opposite the front surface 11a.

[0022] The wafer 11 includes a disk-shaped single crystal substrate 13 having a predetermined diameter (for example, 12 inches (i.e., approximately 300 mm)). The single crystal substrate 13 is made of, for example, silicon, but may also be made of other materials such as silicon carbide (SiC) or gallium nitride (GaN).

[0023] The front surface of the single crystal substrate 13 corresponds to the front surface 11a of the wafer 11, and the back surface of the single crystal substrate 13 corresponds to the back surface 11b of the wafer 11. A plurality of planned dividing lines (streets) are set in a lattice pattern on the front surface of the single crystal substrate 13 (not shown).

[0024] In each of the rectangular areas partitioned by the multiple streets, a device such as an IC (Integrated Circuit) is formed. The device may be, for example, a digital IC such as a logic IC or a memory IC, or an analog IC.

[0025] However, the type of device is not particularly limited. For example, the device may be a light emitting element such as an LED (Light Emitting Diode) or a MEMS (Micro Electro Mechanical System).

[0026] Each device is electrically connected to one or more bumps 15 formed of gold (Au), solder, etc. The bumps 15 and the devices form irregularities on the front surface 11a of the wafer 11.

[0027] A protective film 17 is provided on the surface 11a in a manner that conforms to the irregularities on the surface 11a and adheres to the surface 11a. The protective film 17 is provided, for example, to prevent physical and / or chemical damage to the bumps 15 and the device.

[0028] Protective film 17 is made of resin and has a thickness of 5 μm to 200 μm. However, protective film 17 is not thick enough to absorb the irregularities on surface 11a. Therefore, providing protective film 17 on surface 11a does not completely eliminate the irregularities.

[0029] The protective film 17 has a laminated structure of, for example, an adhesive layer and a base layer, and the adhesive layer side is attached to the surface 11a side. The adhesive layer is made of, for example, an acrylic resin or an epoxy resin, and the base layer is made of, for example, polyolefin or polyvinyl chloride.

[0030] However, the protective film 17 may have only a base material layer without an adhesive layer. In this case, the base material layer is adhered to the surface 11a. The protective film 17 is adhered to the surface 11a by vacuum lamination, thermocompression bonding, pressing, or the like.

[0031] The chuck table 4 is configured to be movable in a horizontal direction perpendicular to the Z-axis direction (e.g., vertical direction, up-down direction) by an X-axis / Y-axis direction movement mechanism (not shown). When the chuck table 4 is in the loading / unloading area A1, the wafer 11 is loaded onto or unloaded from the holding surface 4a.

[0032] When the chuck table 4 is in a coating / degassing area A2 (see FIG. 3) different from the loading / unloading area A1, a coating / heating unit 6 is disposed directly above the holding surface 4a. The coating / heating unit 6 has a dispenser (i.e., a liquid constant amount dispensing device) 8 that applies a liquid resin 21.

[0033] The dispenser 8 is, for example, an air pulse type dispenser. The dispenser 8 includes a syringe 10 containing a liquid resin 21. A controller 12 that controls the timing and amount of dispensing, etc., is connected to the syringe 10. A needle or a nozzle is provided at the lower end of the syringe 10.

[0034] An annular nozzle 14 is disposed on the outer periphery of the lower end of the syringe 10. An opening 14a of the annular nozzle 14 is disposed to face downward and is a slit formed over 360 degrees in the circumferential direction of the annular nozzle 14. However, the annular nozzle 14 may have a plurality of openings 14a disposed at approximately equal intervals over 360 degrees in the circumferential direction of the annular nozzle 14.

[0035] A hot air supply mechanism 16 including a heater, a motor, a fan, etc. is connected to the annular nozzle 14. When the hot air supply mechanism 16 is operated, hot air 14b is ejected downward from the opening 14a (see FIG. 4).

[0036] The annular nozzle 14 is provided with a position adjustment mechanism (not shown) that adjusts its position in the Z-axis direction, and when hot air 14b is ejected, the height position of the annular nozzle 14 is adjusted so that the distance from the opening 14a to the surface 11a is a predetermined distance.

[0037] The annular nozzle 14 and the hot air supply mechanism 16 constitute a heating unit 18 that uses hot air 14b to heat the liquid resin 21. The heating unit 18 heats the liquid resin 21 to a temperature at which the liquid resin 21 does not harden.

[0038] Incidentally, when the chuck table 4 is in the bonding area A3, which is different from the loading / unloading area A1 and the coating / degassing area A2 (see FIG. 6), a pressing unit 20 is disposed above the chuck table 4 disposed in the bonding area A3.

[0039] The pressing unit 20 has an arm 22 that is movable along the Z-axis direction. A ball screw type Z-axis direction movement mechanism (not shown) is attached to the arm 22, for example, and the Z-axis direction position of the arm 22 is adjusted by the Z-axis direction movement mechanism. A disk-shaped suction part 24 is fixed to the lower end of the arm 22.

[0040] The suction unit 24 has substantially the same structure as the chuck table 4, and includes a frame and a porous plate. A negative pressure can be transmitted to the porous plate from a suction source (not shown), and a bottom surface 24a of the suction unit 24 functions as a holding surface that suction-holds the disk-shaped carrier substrate (plate-like object) 23.

[0041] The diameter of the carrier substrate 23 is, for example, approximately equal to the diameter of the wafer 11, but may be larger than the diameter of the wafer 11. The carrier substrate 23 has a predetermined thickness of, for example, 500 μm or more and 1000 μm or less.

[0042] The carrier substrate 23 is a transparent substrate that is transmissive to light in the UV and visible light bands, and may be a glass substrate such as alkali-free glass or quartz glass, a transparent resin substrate such as an acrylic resin, or a single-crystal sapphire substrate.

[0043] The carrier substrate 23 held by suction on the bottom surface 24a is transferred to the wafer 11 held by suction on the holding surface 4a. Thereafter, the chuck table 4 moves horizontally and is placed in the UV irradiation area A4 (see FIG. 7).

[0044] A lamp unit 26 is provided above the chuck table 4, which is disposed in the UV irradiation area A4. The lamp unit 26 includes a plurality of UV lamps 26a capable of emitting UV light. Each UV lamp 26a is a mercury discharge lamp, a metal halide lamp, or the like.

[0045] Next, a more detailed description will be given of a coating method for coating the front surface 11a side with the resin layer 25 using the processing device 2. Fig. 2 shows a holding step S10. In the holding step S10, the back surface 11b side of the wafer 11 is suction-held by the holding surface 4a of the chuck table 4 arranged in the loading / unloading area A1.

[0046] After the holding step S10, the chuck table 4 is moved to the application and degassing area A2. At this time, the position of the chuck table 4 is adjusted so that the center of the surface 11a of the wafer 11 is located substantially directly below the syringe 10 (see FIG. 3).

[0047] Then, the controller 12 is operated to discharge a predetermined amount of liquid resin 21 from the syringe 10. For example, when the thickness of the wafer 11 is reduced to 165 μm by grinding, 15 ml of the liquid resin 21 is applied to the front surface 11a of the wafer 11.

[0048] 3 is a diagram showing an application step S20 in which liquid resin 21 is applied to the center of the front surface 11a of the wafer 11. The liquid resin 21 in the first embodiment is a UV-curable resin that hardens in response to UV.

[0049] Examples of UV curable resins include ResiFlat (both registered trademarks) manufactured and sold by Disco Corporation, and TEMPLOC (both registered trademarks) manufactured and sold by Denka Company Limited, but other UV curable resins may also be used.

[0050] The applied liquid resin 21 is deposited in a dome shape at the center of the surface 11a side. The applied liquid resin 21 contains gas such as air, which is an atmospheric gas, as bubbles 21a due to suck-back in the dispenser 8 or the like.

[0051] Therefore, in this embodiment, after the application step S20, the heating unit 18 is operated to heat the liquid resin 21, thereby bursting the bubbles 21a and removing the bubbles 21a from the liquid resin 21 (heating step S30).

[0052] 4 is a diagram showing the heating step S30. In the heating step S30, the liquid resin 21 is heated to a temperature of 80°C or higher and 200°C or lower, more preferably 90°C or higher and 150°C or lower, and even more preferably 100°C or higher and 120°C or lower.

[0053] The lower limit of the temperature when heating the liquid resin 21 is determined based on, for example, the rating of the heater in the hot air supply mechanism 16, the degree of expansion of the bubbles 21a, etc. The upper limit of the temperature when heating the liquid resin 21 is determined, for example, in consideration of suppressing damage to devices formed on the wafer 11.

[0054] In this embodiment, the distance from the annular nozzle 14 to the liquid resin 21 is adjusted to approximately 50 mm, and then hot air 14b at approximately 100°C is sprayed onto the liquid resin 21 at a speed of 1.5 m / s for approximately 5 seconds. This heats the liquid resin 21 to approximately 100°C. Note that the speed of the hot air 14b is not limited to 1.5 m / s, and may be a predetermined value between 1.0 m / s and 2.0 m / s.

[0055] The heated bubbles 21a expand and eventually reach the gas-liquid interface between the liquid resin 21 and the ambient gas, where they finally burst and disappear. In particular, in this embodiment, hot air 14b is sprayed uniformly downward from the ring-shaped opening 14a. The hot air 14b can apply impact, vibration, etc. to the liquid resin 21.

[0056] In contrast, when supplying heat to the liquid resin 21 via electromagnetic waves (i.e., thermal radiation), or when heat is conducted from a heater placed on the chuck table 4 through the wafer 11, it is difficult to apply impacts, vibrations, etc. to the liquid resin 21, such as those caused by the hot air 14b.

[0057] By using the hot air 14b, it is possible to apply not only heat but also impact, vibration, etc. to the liquid resin 21, and to move the bubbles 21a to the gas-liquid interface and cause them to burst more efficiently than by heat radiation and heat conduction. Figure 5 is a schematic diagram showing the liquid resin 21, etc. after the heating step S30.

[0058] 6, after the heating step S30, the chuck table 4 is moved to the bonding area A3, and the center of the front surface 11a of the wafer 11 is approximately aligned with the center of one surface 23a of the carrier substrate 23. Then, with the other surface 23b of the carrier substrate 23 held by the suction unit 24 facing downward, the arm 22 is moved downward.

[0059] In this embodiment, the chuck table 4 is kept stationary in the Z-axis direction, and the suction part 24 is lowered to press the carrier substrate 23 against the wafer 11 (pressing step S40). Figure 6 is a diagram showing the pressing step S40.

[0060] In the pressing step S40, the liquid resin 21 is pressed and spread over the entire surface 11a side. The amount of pressing of the carrier substrate 23 in the Z-axis direction is adjusted so that the liquid resin 21 has a predetermined thickness 21b. In this way, the wafer 11 and the carrier substrate 23 are bonded together with the protective film 17 and the liquid resin 21 interposed therebetween.

[0061] If the chuck table 4 is provided with a lifting mechanism (not shown), the wafer 11 may be pressed against the carrier substrate 23 by lifting the chuck table 4 while keeping the suction part 24 stationary.

[0062] Alternatively, the wafer 11 and the carrier substrate 23 may be pressed against each other by lowering the suction unit 24 and raising the chuck table 4. That is, at least one of the carrier substrate 23 and the wafer 11 may be pressed against each other.

[0063] 7, after the pressing step S40, the chuck table 4 is moved to the UV irradiation area A4, and the carrier substrate 23 and the like are brought face to face with the lamp unit 26. Then, UV is irradiated onto the liquid resin 21 through the carrier substrate 23 (UV irradiation step S50).

[0064] 7 is a diagram showing the UV irradiation step S50. In the UV irradiation step S50, for example, 50 mW / cm 2 The liquid resin 21 is irradiated with UV light at an illuminance of 1000 uV for 12 seconds. As a result, the liquid resin 21 hardens and becomes a solid resin layer 25.

[0065] In this embodiment, even if air bubbles 21a are mixed in when the liquid resin 21 is applied, the air bubbles 21a can be removed by bursting the air bubbles 21a in the heating step S30. Therefore, compared to when the heating step S30 is not performed, the possibility of damage to the bumps 15, devices, etc. during grinding of the back surface 11b side can be reduced.

[0066] Next, with reference to Figures 8(A) and 8(B), we will explain an experimental example in which air bubbles 21a are removed by spraying hot air 14b onto liquid resin 21. Figure 8(A) is a photograph taken from above of liquid resin 21 before heating step S30, and Figure 8(B) is a photograph taken from above of liquid resin 21 after heating step S30.

[0067] In this experimental example, 15 ml of liquid resin 21 was applied to the protective film 17 provided on the front surface 11a side of the wafer 11 using a dispenser 8. The applied liquid resin 21 contained many air bubbles 21a, as shown in FIG.

[0068] The annular nozzle 14 was placed at a distance of about 50 mm from the liquid resin 21 containing the bubbles 21a, and hot air 14b at about 100°C was sprayed for about 5 seconds. As a result, the bubbles 21a were successfully removed, as shown in Figure 8(B).

[0069] (Second Embodiment) Next, a second embodiment will be described with reference to Figures 9 to 14. In the second embodiment, each step is also performed according to the flow chart shown in Figure 1. However, the second embodiment differs from the first embodiment in that the wafer 11 and the carrier substrate 23 are arranged upside down.

[0070] In the second embodiment, first, as shown in Fig. 9, the back surface 11b side of the wafer 11 is suction-held by the bottom surface (holding surface) 24a of the suction unit (holding table) 24 arranged in the bonding area A3 (holding step S10). Fig. 9 is a diagram showing the holding step S10 according to the second embodiment.

[0071] After the holding step S10, the other surface 23b of the carrier substrate 23 is held by a transparent table 28 arranged in the coating and degassing area A2, as shown in Fig. 10. In the second embodiment, the transparent table 28 is provided instead of the chuck table 4.

[0072] The transparent table 28 is configured to be movable in the horizontal direction by an X-axis and Y-axis direction movement mechanism (not shown), similar to the chuck table 4. A plurality of protrusions (not shown) are provided on the upper surface 28a of the transparent table 28 to prevent the carrier substrate 23 from shifting in position.

[0073] The position of the carrier substrate 23 within the upper surface 28a is fixed by the multiple protrusions contacting the outer periphery of the carrier substrate 23. Note that instead of the multiple protrusions, suction holding by negative pressure, clamps that clamp the outer periphery of the carrier substrate 23, or the like may be used.

[0074] The transparent table 28 includes a transparent substrate that is transparent to light in the UV and visible light bands, similar to the carrier substrate 23. The liquid resin 21 is applied to one surface 23a of the carrier substrate 23 fixed to the upper surface 28a (application step S20).

[0075] 10 is a diagram showing the application step S20 according to the second embodiment. The amount of liquid resin 21 applied is the same as in the first embodiment. After the application step S20, the liquid resin 21 is heated by spraying hot air 14b from the annular nozzle 14 (heating step S30), as in the first embodiment.

[0076] Fig. 11 is a diagram showing the heating step S30 according to the second embodiment. As described above, in the heating step S30, the bubbles 21a can be removed by bursting them. Fig. 12 is a schematic diagram showing the liquid resin 21 and the like after the heating step S30 according to the second embodiment.

[0077] After the heating step S30, the transparent table 28 is moved to the bonding area A3. Then, the suction unit 24 is lowered to press the wafer 11 against the carrier substrate 23 (pressing step S40). Figure 13 is a diagram showing the pressing step S40 according to the second embodiment.

[0078] If the transparent table 28 is provided with a lifting mechanism (not shown), the carrier substrate 23 may be pressed against the wafer 11 by lifting the transparent table 28 while keeping the suction unit 24 stationary.

[0079] Alternatively, the wafer 11 and the carrier substrate 23 may be pressed against each other by lowering the suction unit 24 and raising the transparent table 28. That is, at least one of the wafer 11 and the carrier substrate 23 may be pressed against each other.

[0080] After the pressing step S40, the transparent table 28 is moved to the UV irradiation area A4, and UV is irradiated from the lamp unit 26 to the liquid resin 21 via the transparent table 28 and the carrier substrate 23 in the same manner as in the first embodiment (UV irradiation step S50).

[0081] The UV irradiation step S50 hardens the liquid resin 21 to form a solid resin layer 25. Fig. 14 is a diagram showing the UV irradiation step S50 according to the second embodiment. In the second embodiment, the air bubbles 21a can also be removed by bursting the air bubbles 21a in the heating step S30.

[0082] (Third Embodiment) Next, a third embodiment will be described with reference to Fig. 15 and Fig. 16. Fig. 15 is a flow diagram of a coating method according to the third embodiment. The third embodiment differs from the first and second embodiments in that a thermosetting resin is used as the liquid resin 21 instead of a UV-curable resin.

[0083] 2 to 6 of the first embodiment, a third embodiment will be described. After the holding step S10 (see FIG. 2), a liquid resin (thermosetting resin) 21 is applied to the front surface 11a of the wafer 11 in an application step S20 (see FIG. 3).

[0084] In the subsequent heating step S30 (see FIG. 4), the liquid resin (thermosetting resin) 21 is heated to a predetermined temperature at which the liquid resin 21 does not harden. The thermosetting resin contains, for example, an epoxy resin and a hardener, and hardens at a predetermined temperature of 150° C. or higher (for example, 200° C.).

[0085] Therefore, in the heating step S30 of the second embodiment, the liquid resin 21 is heated to a temperature of 80°C or higher but lower than 150°C, more preferably 90°C or higher but lower than 130°C, and even more preferably 100°C or higher but lower than 110°C, so that the liquid resin 21 does not harden due to heat.

[0086] The lower limit of the temperature when heating the liquid resin 21 is determined in the same manner as in the first embodiment. The upper limit of the temperature when heating the liquid resin 21 is determined taking into consideration not only the prevention of damage to the device but also the prevention of hardening of the thermosetting resin.

[0087] In the heating step S30 of the third embodiment, for example, the distance from the annular nozzle 14 to the liquid resin 21 is adjusted to about 50 mm, and then hot air 14b at about 100° C. is sprayed onto the liquid resin 21 for about 5 seconds to heat the liquid resin 21 to about 100° C. This causes the bubbles 21a to burst and be removed (see FIGS. 4 and 5).

[0088] In the subsequent pressing step S40 (see FIG. 6), the chuck table 4 is made stationary in the Z-axis direction, and the suction part 24 is lowered to press the carrier substrate 23 against the wafer 11. Note that at least one of the carrier substrate 23 and the wafer 11 may be pressed.

[0089] In the third embodiment, the liquid resin 21 is cured by heat rather than UV, so the carrier substrate 23 does not need to have much transmittance to light such as UV. For example, the carrier substrate 23 is made of a material having a linear thermal expansion coefficient substantially equal to that of the wafer 11.

[0090] Specifically, when the wafer 11 has a single crystal silicon substrate, a carrier substrate 23 made of alumina (Al2O3), aluminum nitride (AlN), silicon nitride (Si3N4), silicon carbide (SiC), or the like is used.

[0091] By making the linear thermal expansion coefficients of the wafer 11 and the carrier substrate 23 approximately equal, the amount of warping that occurs in the laminate including the carrier substrate 23, wafer 11, etc. due to the heat applied when hardening the liquid resin 21 can be reduced.

[0092] After the pressing step S40, the liquid resin 21 (i.e., thermosetting resin) is heated and cured (thermosetting step S55). In the thermosetting step S55, the liquid resin 21 is heated to a predetermined temperature of 150° C. or higher to be cured.

[0093] 16 is a diagram showing a thermal curing step S55 according to the third embodiment. In the thermal curing step S55, first, the chuck table 4 is moved to a thermal curing area A5 different from the carry-in / carry-out area A1, the coating / deaeration area A2, and the bonding area A3.

[0094] A disk-shaped heater unit 30 is disposed above the chuck table 4 arranged in the thermal curing area A5. Similar to the pressing unit 20, the heater unit 30 is provided with a ball screw type Z-axis direction movement mechanism (not shown).

[0095] The heater unit 30 includes a plurality of concentrically arranged ring-shaped resistance heating elements 32. Each resistance heating element 32 is covered with an insulator 34 and forms a disk-shaped heating portion.

[0096] The heater unit 30 includes a disk-shaped frame 36 made of metal. A disk-shaped recess is formed in the bottom of the frame 36, and the heat generating portion described above is fixed in this recess. The heater unit 30 may also include a temperature measurement mechanism, a cooling mechanism, etc.

[0097] By heating the heat generating portion to, for example, 200°C while the underside of the heater unit 30 is in contact with the carrier substrate 23, heat 32a is transferred to the liquid resin 21 via the carrier substrate 23, and the liquid resin 21 is also heated to 200°C and hardened.

[0098] In this embodiment, heat 32a is transferred to the liquid resin 21 via the carrier substrate 23, which reduces thermal damage to the bumps 15, devices, etc. compared to when a heat generating portion is provided on the chuck table 4 and the liquid resin 21 is heated via the wafer 11.

[0099] Incidentally, in the third embodiment, as in the second embodiment, the liquid resin 21 (i.e., thermosetting resin) may be applied to one surface 23a of the carrier substrate 23. However, in this case, UV is not used, and the chuck table 4 is used instead of the transparent table 28, and the carrier substrate 23 is suction-held by the holding surface 4a.

[0100] (Fourth embodiment) Next, a fourth embodiment will be described with reference to Fig. 17 and Fig. 18. Fig. 17 is a flow diagram of a coating method according to the fourth embodiment. The fourth embodiment differs from the above-described embodiments in that after the application step S20, ultrasonic waves are applied to the liquid resin 21 instead of hot air 14b.

[0101] The holding step S10 and the application step S20 are the same as those in the first embodiment, and therefore their explanations are omitted. In the ultrasonic application step S35, an ultrasonic application unit 40 is used as shown in Fig. 18. The ultrasonic application unit 40 is disposed, for example, in a position in the application / deaeration area A2 so as not to interfere with the dispenser 8.

[0102] The ultrasonic wave application unit 40 is configured to be movable along the Z-axis direction by a ball screw type Z-axis direction movement mechanism (not shown). The ultrasonic wave application unit 40 has an ultrasonic vibrator (not shown) that converts electric power into ultrasonic vibration. The ultrasonic vibrator contains, for example, lead zirconate titanate.

[0103] A horn 42 that functions as a resonator is attached to the ultrasonic vibrator. A nozzle 46 is provided near the horn 42. The nozzle 46 supplies a liquid 44, such as pure water, that functions as an acoustic matching layer between the liquid resin 21 and the horn 42.

[0104] 18 is a diagram showing an ultrasonic wave applying step S35 according to the fourth embodiment. In the ultrasonic wave applying step S35, the liquid 44 is supplied onto the liquid resin 21 at a predetermined flow rate, thereby covering the liquid resin 21 with the liquid 44.

[0105] Then, ultrasonic waves having a predetermined frequency of 20 kHz or more are applied from horn 42 to liquid resin 21 through liquid 44. This causes bubbles 21a to vibrate, and adjacent bubbles 21a connect with each other, increasing the volume.

[0106] The bubbles 21a, whose volume has increased, eventually burst when they reach the interface between the liquid resin 21 and the liquid 44. The gas in the bubbles 21a is then removed by the flow of the liquid 44.

[0107] The pressing step S40 and UV irradiation step S50 that follow the ultrasonic wave application step S35 are similar to those in the first embodiment, and therefore will not be described here. Note that the ultrasonic wave application step S35 may also be applied to the second embodiment (see FIG. 19).

[0108] 19 is a diagram showing an ultrasonic wave application step S35 according to a fifth embodiment. In the fifth embodiment, ultrasonic waves are applied from a horn 42 to a liquid resin 21 via a liquid 44, thereby bursting and removing air bubbles 21a contained in the liquid resin 21.

[0109] (Sixth embodiment) The ultrasonic wave application step S35 may be applied (see FIG. 20) to the third embodiment (see FIGS. 15 and 16) that uses the liquid resin 21 (thermosetting resin). Figure 20 is a flow diagram of the coating method according to the sixth embodiment.

[0110] In the sixth embodiment, even if air bubbles 21a are mixed in when the liquid resin 21 is applied, the air bubbles 21a can be removed by bursting the air bubbles 21a in the ultrasonic application step S35. Similarly, the ultrasonic application step S35 may be applied when applying the liquid resin 21 (i.e., thermosetting resin) to one surface 23a of the carrier substrate 23.

[0111] In addition, the structures, methods, etc. according to the above-described embodiments may be modified as appropriate without departing from the scope of the present invention. In the pressing step S40, the carrier substrate 23 and the wafer 11 may be brought closer to each other by repeatedly moving the surface 11a side in contact with the liquid resin 21 and relatively moving closer to and away from each other multiple times until the liquid resin 21 reaches a predetermined thickness 21b. [Explanation of symbols]

[0112] 2: Processing device, 4: Chuck table (holding table), 4a: Holding surface 6: Application heating unit, 8: Dispenser, 10: Syringe, 12: Controller 11: wafer, 11a: front surface, 11b: back surface 13: Single crystal substrate, 15: Bump, 17: Protective film 14: Annular nozzle, 14a: Opening, 14b: Hot air 16: Hot air supply mechanism, 18: Heating unit 20: Pressing unit, 22: Arm 24: suction part (holding table), 24a: bottom surface (holding surface) 21: liquid resin, 21a: bubbles, 21b: thickness 23: Carrier substrate (plate-like object), 23a: One surface, 23b: Other surface 25: Resin layer (solid resin) 26: Lamp unit, 26a: UV lamp 28: transparent table, 28a: top surface 30: heater unit, 32: resistance heating element, 32a: heat, 34: insulator, 36: frame 40: ultrasonic wave application unit, 42: horn, 44: liquid, 46: nozzle A1: Loading / unloading area, A2: Coating / degassing area, A3: Bonding area, A4: UV irradiation area A5:Thermosetting area S10: Holding step, S20: Application step S30: Heating step, S35: Ultrasonic application step S40: Pressing step S50: UV irradiation step, S55: heat curing step

Claims

1. A coating method for covering a front surface side of a wafer with a solid resin, comprising: a holding step of holding a back side of the wafer, which is located opposite to the front side, by a holding table; After the holding step, a coating step of coating the front surface side of the wafer or the plate-like object with a liquid resin; a heating step of heating the liquid resin after the applying step; a pressing step of pressing at least one of the plate-like object and the wafer together via the liquid resin after the heating step; Equipped with The coating method is characterized in that the heating step causes bubbles contained in the liquid resin to burst.

2. 2. The coating method according to claim 1, wherein the liquid resin is heated by a jet of hot air in the heating step.

3. A coating method for covering a front surface side of a wafer with a solid resin, comprising: a holding step of holding a back side of the wafer, which is located opposite to the front side, by a holding table; After the holding step, a coating step of coating the front surface side of the wafer or the plate-like object with a liquid resin; After the application step, an ultrasonic wave application step of applying ultrasonic waves to the liquid resin; a pressing step of pressing at least one of the plate-like object and the wafer together via the liquid resin after the ultrasonic wave application step; Equipped with The coating method is characterized in that air bubbles contained in the liquid resin are burst by the ultrasonic application step.

4. the liquid resin is a UV-curable resin, the plate-like object is a transparent substrate that is transparent to UV light, 4. The coating method according to claim 1, further comprising a UV irradiation step of irradiating the UV curable resin with UV light through the plate-like object after the pressing step.

5. the liquid resin is a thermosetting resin, 4. The coating method according to claim 1, further comprising a heat curing step of heating and curing the thermosetting resin after the pressing step.

6. A coating method as described in any one of claims 1 to 3, characterized in that in the coating step, the liquid resin is applied to only one of the front surface side of the wafer or the plate-like object.

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