Dipping device, die bonding device, and method for manufacturing semiconductor device

Abstract

To provide a technique capable of forming a more uniform flux thin film.SOLUTION: A dipping device includes a squeegee device and a plate for forming a film of flux. A surface of the plate has a roughened surface of nanometer-level arithmetic mean roughness. The dipping device is configured to move the squeegee device and the plate relative to each other and supply the flux from the squeegee device to the roughened surface of the plate.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present disclosure relates to a die bonding apparatus and is applicable to, for example, a die bonding apparatus that performs flux transfer.

Background Art

[0002] In a die bonding apparatus that mounts a semiconductor chip called a die on the surface of, for example, a wiring board or a lead frame (hereinafter collectively referred to as a substrate), there is a flip chip bonder that picks up a divided die from a semiconductor wafer (simply referred to as a wafer), turns the die over so that the surface faces down (face down), and mounts it on the substrate. Some flip chip bonders have a dipping process of applying flux to bumps, which are protruding connection electrodes provided on the surface of the die. Here, the flux is a soldering accelerator and has a purification action of removing foreign substances and oxide films, an antioxidant action of preventing oxidation of the joint, and a surface tension reduction action of suppressing the melting of the molten solder from becoming round.

[0003] In the dipping process, the bonding head moves up and down, immerses the bump surface of the die in a concave cavity provided in the coating device and storing the flux, and transfers the flux to the bumps. Further, the coating device is provided with a mechanism for replenishing the flux in the cavity lost by the transfer. This mechanism is performed by moving a container with an open bottom and storing the flux on a plate having a cavity. Such a coating device is disclosed in Patent Document 1.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Generally, the film thickness of the flux transferred to the bumps is about one-third of the diameter of the bumps. For example, in the case of C4 (Controlled Collapse Chip Connection) bumps with a bump diameter of φ75 to 150 μm, the flux film thickness is 30 to 100 μm, and in the case of C2 (Chip Connection) bumps with a φ55 to 100 μm, the flux film thickness is 10 to 30 μm. Therefore, as the bump pitch becomes narrower and the bump diameter becomes smaller, it is necessary to reduce the film thickness of the flux. When forming the flux film with a reduced thickness, the flux does not uniformly wet the plate, resulting in unevenness and making it difficult to form a uniform thin film.

[0006] The problem of the present disclosure is to provide a technique capable of forming a more uniform flux thin film.

Means for Solving the Problem

[0007] The outline of typical ones among the present disclosures will be briefly described as follows. That is, the dipping device includes a squeegee device and a plate for forming a flux film. The surface of the plate has a rough surface with an arithmetic mean roughness at the nanolevel. The squeegee device and the plate are relatively moved, and the flux is configured to be supplied from the squeegee device to the rough surface of the plate.

Effect of the Invention

[0008] According to the present disclosure, it becomes possible to form a more uniform flux thin film.

Brief Description of the Drawings

[0009]

Figure 1

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Figure 14

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Figure 17

Figure 18

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments will be described with reference to the drawings. However, in the following description, the same reference numerals may be given to the same components and repeated descriptions may be omitted. Note that, for the sake of clarity of the description, the drawings may schematically represent the width, thickness, shape, etc. of each part as compared with the actual aspect, but this is merely an example and does not limit the interpretation of the present disclosure.

[0011] A flip chip bonder as a die bonding apparatus will be described. The flip chip bonder in the embodiment is used, for example, in the manufacture of a fan out type panel level package (FOPLP) or the like, which is a package for forming a redistribution layer in a wide area exceeding the chip area.

[0012] (Configuration of Flip Chip Bonder) FIG. 1 is a perspective view showing a schematic configuration of a flip chip bonder in an embodiment. FIG. 2 is a diagram for explaining the operations of a pickup flip head and a transfer head when viewed from the direction of arrow A in FIG. 1. FIG. 3 is a diagram for explaining the operations of an intermediate stage and a bond head when viewed from the direction of arrow B in FIG. 1. FIG. 4 is a schematic cross-sectional view showing the main part of the die supply unit shown in FIG. 1.

[0013] As shown in FIG. 1, the flip chip bonder 10 generally includes a die supply unit 1, a pickup unit 2, an intermediate stage unit 3, a bonding unit 4, and a control device 7 that monitors and controls the operations of each unit. The flip chip bonder 10 performs face-down bonding in which the surface (bump surface) of the die D is placed downward on the substrate.

[0014] (Die Supply Unit) The die supply unit 1 supplies the die D to be mounted on a substrate P, which is an example of a workpiece. As shown in FIG. 4, the die supply unit 1 includes a wafer holding stage 12 that holds the divided wafer 11, and a pushing-up unit 13 that pushes up the die D from the wafer 11. The wafer holding stage 12 is moved in the XY directions by a wafer holding stage table 19 as a drive mechanism shown in FIG. 1, and moves the die D to be picked up to the position of the pushing-up unit 13. A wafer cassette (not shown) in which the wafer ring 14 is stored is supplied from the outside of the flip chip bonder 10. The wafer ring 14 is a jig to which the wafer 11 is fixed and can be attached to the wafer holding stage 12.

[0015] As shown in FIG. 4, the wafer holding stage 12 has an expand ring 15 that holds the wafer ring 14, a support ring 17 that horizontally positions a dicing tape 16 on which a plurality of dies D are adhered and held by the wafer ring 14, and a pushing-up unit 13 for pushing up the die D upward. In order to pick up a predetermined die D, the pushing-up unit 13 is configured to move in the vertical direction by a drive mechanism (not shown).

[0016] On the dicing tape 16, the surface of the die D faces upward, and, as shown in FIG. 4, for example, bumps Db are provided on the surface of the die D for which face-down bonding is performed. Note that the bumps Db are, for example, convex and are provided in a plurality of discrete locations on the surface of the die D.

[0017] (Pickup Unit) The pickup unit 2 includes a pickup flip head 21 that picks up and inverts the die D, a wafer recognition camera 24, a transfer head 25, and a drive unit 27 that moves the transfer head 25 up and down and along the X-axis direction.

[0018] The pickup flip head 21 moves up and down, rotates, and moves along the X-axis direction by a drive unit (not shown). The pickup flip head 21 rotates within the XZ plane about a rotation axis along the Y-axis direction to invert the picked-up die D. As shown in FIG. 2, the pickup flip head 21 has a collet 22 that adsorbs and holds the die D at its tip, and the transfer head 25 has a collet 26 that adsorbs and holds the die D at its tip. The wafer recognition camera 24 is provided directly above the die D to be picked up. With such a configuration, the pickup flip head 21 picks up the die D based on the imaging data of the wafer recognition camera 24, inverts the die D by rotating the pickup flip head 21 by 180 degrees so that the back surface faces upward, and assumes a posture to transfer the die D to the transfer head 25.

[0019] The transfer head 25 is configured to receive the inverted die D from the pickup flip head 21 and move along the X-axis direction by the drive unit 27 to place it on the intermediate stage unit 3.

[0020] (Intermediate stage unit) The intermediate stage unit 3 includes a first intermediate stage 31_1 and a second intermediate stage 31_2 on which the die D is temporarily placed, and an under vision camera 34. The first intermediate stage 31_1 and the second intermediate stage 31_2 are movable along the Y-axis direction by a drive unit (not shown). Further, the second intermediate stage 31_2 is provided with a dipping mechanism described later.

[0021] As shown in FIG. 3, the first intermediate stage 31_1 and the second intermediate stage 31_2 are movable in the Y-axis direction to the first position P1, the second position P2, and the third position P3. Here, the first position P1 is the handover position of the die D with the transfer head 25. The second position P2 is the flux film formation position, which will be described later, on the second intermediate stage 31_2. The third position P3 is the handover position of the die D with the bond head 41. The under vision camera 34 images the lower surface of the die D held by the bond head 41. Here, the lower surface of the die D is the surface side of the die D provided with the bumps Db.

[0022] (Bonding portion) The bonding portion 4 includes a bond head 41, a bond head table 45, a gantry table (Y beam) 43, a pair of X beams (not shown) that move the gantry table 43 along the X-axis direction, and a bond camera 44. As shown in FIG. 3, the bond head 41 has a collet 42 that sucks and holds the die D at its tip. The bond head 41 picks up the die D from the first intermediate stage 31_1 or the second intermediate stage 31_2 and bonds it onto the substrate P being conveyed. When the die D is bonded to the substrate P, the substrate P is adsorbed and fixed to the bond stage BS. The bond head table 45 moves the bond head 41 along the Z-axis direction. The gantry table 43 extends along the Y-axis direction so as to straddle the bond stage BS, and both ends thereof are supported by a pair of X beams that are movable along the X-axis direction. The gantry table 43 moves the bond head table 45 along the Y-axis direction. The bond camera 44 is provided on the bond head table 45. The bond camera 44 images the position recognition mark (not shown) of the substrate P and recognizes the bonding position.

[0023] With such a configuration, the bond head 41 picks up the die D from the first intermediate stage 31_1 or the second intermediate stage 31_2, and the under vision camera 34 and the bond camera 44 image the state in which the bond head 41 holds the die D and the position where the die D is to be bonded. Based on this imaging data, the bonding positioning correction position is calculated, and the bond head 41 is moved to bond the die D to the substrate P.

[0024] Although not shown, the flip chip bonder 10 includes a set of parallel transfer rails for moving the substrate P along the X-axis direction, a substrate supply unit for supplying the substrate P carried in from the outside of the flip chip bonder 10 to the transfer rails, and a substrate discharge unit for discharging the substrate P on which the die D is placed to the outside of the flip chip bonder 10. With such a configuration, the substrate P is supplied from the substrate supply unit, moved along the transfer rails to the bonding position, and after bonding, moved to the substrate discharge unit and the substrate P is passed to the substrate discharge unit. During the bonding of the die D to the substrate P, the substrate supply unit supplies a new substrate P and waits on the transfer rails.

[0025] The control device 7 includes a storage device (memory) for storing a program (software) and data for monitoring and controlling the operations of each part of the flip chip bonder 10, and a central processing unit (CPU) for executing the program stored in the memory.

[0026] (Dipping mechanism) The configuration and operation of the dipping mechanism provided in the second intermediate stage 31_2 will be described with reference to FIGS. 5 and 6. FIG. 5 is a side view of the dipping mechanism of the second intermediate stage viewed from a direction perpendicular to the moving direction of the second intermediate stage. FIG. 6 is a cross-sectional view taken along the line C-C shown in FIG. 5.

[0027] Dipping, which applies flux to the bumps Db of die D, is performed by immersing the bumps Db of die D in a concave cavity in which the flux is stored. This is called flux transfer. Also, the flux in the cavity lost by application is replenished. This is called flux film formation. The mechanism that performs these flux transfer and flux film formation is called a dipping mechanism or dipping device.

[0028] As shown in FIG. 5, the dipping mechanism 8 includes a squeegee device 81 and a plate 82p in which a storage portion 82d for the flux F formed in a recess is incorporated. The plate 82p can move along the Y-axis direction below the squeegee device 81. When the plate 82p moves, the flux F is supplied from the squeegee device 81 to the storage portion 82d and uniformly forms a film. The flux F supplied to the storage portion 82d may be not only the flux alone but also a substance having flexibility and affinity for the flux, for example, a very soft gel-like material mainly made of silicone mixed with the flux.

[0029] The squeegee device 81 is uniformly filled with the flux F and uniformly replenishes the flux F from the opening provided at the bottom to the storage portion 82d. The opening at the bottom of the squeegee device 81 has a long side that is equal to or greater than the width of the storage portion 82d in the X-axis direction. A guide slider 81s extending along the Y-axis direction is provided below the squeegee device 81.

[0030] The storage portion 82d provided in the plate 82p has a concave shape. The transfer head 25 or the bond head 41 descends into the storage portion 82d and immerses the bumps Db of die D to transfer the flux. In FIG. 5, only one storage portion 82d is provided, but a plurality of storage portions 82d may be provided. The depth of the storage portion 82d is approximately 1 / 2 to 2 / 3 of the thickness (tb) of the bump Db. For example, if tb = 30 μm, the depth of the storage portion 82d is approximately 15 μm to 20 μm.

[0031] Plate 82p has plate 82k below it, and plate 82k has a guide rail 82g extending along the Y-axis direction on its upper surface. The guide rail 82g can move under the guide slider 81s, and the plate 82p can move along the Y-axis direction under the squeegee device 81. For example, by fixing the squeegee device 81 with the squeegee lock 83 and moving the plate 82p, flux can be deposited on the accommodating portion 82d.

[0032] When the die D provided with bumps Db is immersed in the accommodating portion 82d by the transfer head 25 or the bond head 41, solder flux F is uniformly applied to all the bumps Db. Then, the die D with the flux transferred to the bumps Db by the bond head 41 is picked up or lifted from the accommodating portion 82d.

[0033] The flux deposition operation by the second intermediate stage 31_2 will be described below. First, the second intermediate stage 31_2 moves to the flux deposition position, and the squeegee lock 83 is lowered by a driving portion (not shown) to fix the squeegee device 81.

[0034] Next, the second intermediate stage 31_2 moves along the Y-axis direction from left to right in the figure. As a result, the guide rail 82g provided on the plate 82k moves along the Y-axis direction under the guide slider 81s provided on the squeegee device 81, and the squeegee device 81 moves relative to the plate 82p along the Y-axis direction from the right end to the left end of the plate 82p. As a result, the flux F in the squeegee device 81 is supplied into the accommodating portion 82d of the plate 82p. Next, the second intermediate stage 31_2 is moved along the Y-axis direction from right to left in the figure, so that the squeegee device 81 moves relative to the plate 82p along the Y-axis direction from the left end to the right end of the plate 82p. As a result, the flux F in the squeegee device 81 is supplied into the accommodating portion 82d of the plate 82p. By this reciprocating operation of the second intermediate stage 31_2, flux is deposited in the accommodating portion 82d of the plate 82p.

[0035] Finally, the squeegee lock 83 rises to release the fixing of the squeegee device 81.

[0036] Next, a method for manufacturing a semiconductor device using a flip chip bonder 10 will be described with reference to FIGS. 1, 2, 4, 5, and 7. FIG. 7 is a flowchart showing a face-down bonding method implemented by the flip chip bonder shown in FIG. 1.

[0037] In the flip chip bonder 10, a plurality of face-down bonding methods can be implemented. In the first face-down bonding method, the second intermediate stage 31_2 as a flux transfer stage is used, and the die is immersed in the flux by the transfer head 25 to perform flux transfer. In the second face-down bonding method, the first intermediate stage 31_1 and the second intermediate stage 31_2 as a flux transfer stage are used, and the die is immersed in the flux by the bond head 41 to perform flux transfer. In the third face-down bonding method, in the second face-down bonding method, the die is imaged before and after flux transfer, and transfer misalignment is confirmed. In the following method for manufacturing a semiconductor device, an example using the first face-down bonding method will be described.

[0038] In the die bonding step of the method for manufacturing a semiconductor device according to the embodiment, first, a wafer ring 14 holding a dicing tape 16 to which a die D obtained by dividing the wafer 11 shown in FIG. 4 is attached is carried into the flip chip bonder 10. The control device 7 places the wafer ring 14 holding the wafer 11 on the wafer holding stage 12 of the die supply unit 1. Further, a substrate P is prepared and carried into the flip chip bonder 10.

[0039] (Step S1: Wafer Die Recognition) The control device 7 moves the wafer chuck table 12 to the reference position where the die D is picked up by the wafer chuck table 19. Next, the control device 7 images the die D to be picked up by the wafer recognition camera 24, and performs fine adjustment (alignment) so that the placement position of the wafer 11 exactly matches the reference position from the acquired image. That is, the control device 7 moves the wafer chuck table 12 shown in FIG. 4 so that the die D to be picked up is positioned directly above the push-up unit 13 by the wafer chuck table 19, and positions the die to be peeled between the push-up unit 13 and the collet 22.

[0040] (Step S2: Wafer die pickup) As shown in FIG. 2, the control device 7 moves the push-up unit 13 upward so that the upper surface of the push-up unit 13 contacts the back surface of the dicing tape 16. At this time, the control device 7 adsorbs the dicing tape 16 to the upper surface of the push-up unit 13. The control device 7 lowers the collet 22 while evacuating it, lands it on the die D to be peeled, and adsorbs the die D. The control device 7 raises the collet 22 to peel the die D from the dicing tape 16. Thereby, the die D is picked up by the pickup flip head 21.

[0041] (Step S3: Pickup flip head movement) The control device 7 moves the pickup flip head 21 from the pickup position to the inversion position.

[0042] (Step S4: Pickup flip head inversion) As shown in FIG. 2, the control device 7 rotates the pickup flip head 21 by 180 degrees, inverts the surface (front surface) on which the bumps Db of the die D are formed downward, and positions the die D to be handed over to the transfer head 25.

[0043] (Step S5: Transfer head delivery) As shown in FIG. 2, the control device 7 lowers the collet 26 while evacuating it, lands it on the die D held by the pickup flip head 21, and adsorbs the die D. The adsorption by the collet 22 of the pickup flip head 21 is released, and the collet 26 of the transfer head 25 is raised to pick up the die D. Thereby, the die D is delivered to the transfer head 25.

[0044] (Step S6: Pickup Flip Head Inversion) As shown in FIG. 2, the control device 7 rotates the pickup flip head 21 and turns the adsorption surface of the collet 22 downward.

[0045] (Step S7b: Transfer Head Movement) As shown in FIG. 1, before or in parallel with Step S6, the control device 7 moves the transfer head 25 along the X-axis direction from the zero position P0, which is the die D delivery position with the pickup flip head 21, to above the second intermediate stage 31_2 by the drive unit 27. Here, the second intermediate stage 31_2 is located at the first position P1 in the Y-axis direction.

[0046] (Step S8b: Placing the Die on the Second Intermediate Stage and Flux Transfer) As shown in FIG. 1, the control device 7 lowers the transfer head 25 to place the die D held by the transfer head 25 in the accommodation part 82d provided on the second intermediate stage 31_2. Thereby, the bump Db of the die D is immersed in the flux F formed on the accommodation part 82d, and the flux is transferred.

[0047] (Step S9b: Transfer Head Movement) As shown in FIG. 1, the control device 7 raises the transfer head 25 and moves the transfer head 25 along the X-axis direction to the zero position P0. In this state, the bond head 41 is moved to the third position P3 by the X beam and the gantry table 43. The second intermediate stage 31_2 is waiting at the third position P3.

[0048] (Step S10b: Movement to the Second Intermediate Stage Position) As shown in FIG. 1, after or in parallel with step S9b, the control device 7 moves the second intermediate stage 31_2 from the first position P1 to the third position P3 along the Y-axis direction. At this time, the die D is immersed in the flux of the accommodating portion 82d.

[0049] (Step S11b: Recognition of the Die Position on the Second Intermediate Stage) As shown in FIGS. 1 and 3, after step S10b, before moving the bonding head 41 to the third position P3, the control device 7 images the die D placed on the second intermediate stage 31_2 with the bonding camera 44 to recognize the position of the die D. The control device 7 may correct the position of the die D with the bonding head 41 based on the recognition result.

[0050] (Step S12b: Delivery of the Bonding Head) As shown in FIG. 1, the control device 7 lowers the bonding head 41 with the bonding head table 45 and adsorbs the die D on which the flux F has been transferred to the bump Db by the collet of the bonding head 41. Then, the control device 7 raises the bonding head 41 with the bonding head table 45 to pick up the die D from the second intermediate stage 31_2. Thereby, the delivery of the die D is performed. In this state, the control device 7 picks up the die D from the pickup flip head 21 with the transfer head 25.

[0051] (Step S24b: Movement to the Second Intermediate Stage Position) As shown in FIG. 1, after or in parallel with step S14b, the control device 7 moves the second intermediate stage 31_2 from the third position P3 to the second position P2 along the Y-axis direction. Here, the second intermediate stage 31_2 is located at the second position P2, but it may be located between the third position P3 and the first position P1 or may not move and be located at the third position P3.

[0052] (Step S25b: Flux Film Formation) As shown in FIGS. 1 and 5, the control device 7 lowers the squeegee lock 83 to fix the squeegee device 81, and moves the second intermediate stage 31_2 (plate 82p) further in the direction opposite to the first position P1 from the second position P2 along the Y-axis direction. Thereby, the flux F is supplied from the squeegee device 81 to the accommodation portion 82d of the plate 82p, and the flux is formed into a film. Then, the control device 7 measures the film thickness of the formed flux by a film thickness measuring device 91 such as a laser displacement meter. In this state, the control device 7 moves the bond head 41 from the third position P3 above the substrate P by the X beam and the gantry table 43. Further, the transfer head 25 is moved to the first position P1 by the drive unit 27.

[0053] (Step S13b: Second intermediate stage position movement) As shown in FIG. 1, the control device 7 moves the second intermediate stage 31_2 from the second position P2 to the first position P1 along the Y-axis direction.

[0054] (Step S14b: Bond head movement) As shown in FIG. 1, in parallel with step S24b, the control device 7 raises and lowers the bond head 41 by the bond head table 45, and moves the die D held by the collet 42 of the bond head 41 from above the second intermediate stage 31_2 onto the under vision camera 34 by the X beam and the gantry table 43.

[0055] (Step S15: Pickup die position recognition) As shown in FIG. 1, the control device 7 images the die D held by the collet 42 of the bond head 41 by the under vision camera 34 to recognize the position of the die D.

[0056] (Step S16: Bond head movement) As shown in FIG. 1, the control device 7 moves the die D held by the collet 42 of the bond head 41 from above the under vision camera 34 to above the substrate P by the X beam and the gantry table 43. In this state, the second intermediate stage 31_2 is performing a flux film forming operation (step S25b). Also, the transfer head 25 picks up the next die D from the pickup flip head 21 and moves to the first position P1. The first intermediate stage 31_1 is waiting at the third position P3.

[0057] (Step S17: Bond) As shown in FIG. 1, the control device 7 lowers the bond head 41 by the bond head table 45 and bonds the die D held by the collet 42 of the bond head 41 onto the substrate P. In this state, the second intermediate stage 31_2 has completed the flux film forming. Also, the transfer head 25 is holding the next die D and waiting at the first position P1. The first intermediate stage 31_1 is waiting at the third position P3.

[0058] (Step S18: Bond head movement) After the control device 7 raises and lowers the bond head 41 by the bond head table 45, it moves the bond head 41 (bond camera 44) to the appearance inspection position above the substrate P by the X beam and the gantry table 43.

[0059] (Step S19: Bond appearance inspection) The control device 7 images the die D bonded onto the substrate P by the bond camera 44 to inspect the appearance.

[0060] (Step S20b: Bond head movement) As shown in FIG. 1, the control device 7 raises and lowers the bonding head 41 by the bonding head table 45, and moves the bonding head 41 from the appearance inspection position above the substrate P to above the second intermediate stage 31_2 located at the third position P3 by the X beam and the gantry table 43. In this state, the second intermediate stage 31_2 has been subjected to flux film formation. Also, the transfer head 25 is moving from the first position P1 to the zero position P0 to pick up the next die D.

[0061] Also, when the bonding of all the dies D to the substrate P is completed, after step S19, the control device 7 takes out the substrate P to which the die D is bonded from the transfer rail at the substrate carry-out section. The substrate P is carried out from the flip chip bonder 10.

[0062] Thereafter, a sealing body including a plurality of semiconductor chips and a sealing resin covering the plurality of semiconductor chips is formed by collectively sealing the plurality of dies (semiconductor chips) arranged on the substrate P with a sealing resin. Thereafter, the substrate P is peeled off from the sealing body, and then a redistribution layer is formed on the surface of the sealing body to which the substrate P was attached to manufacture FOPLP.

[0063] In the first face-down bonding method according to the present embodiment, as shown in FIG. 1, the die D is immersed in the flux in the accommodation portion 82d of the second intermediate stage 31_2 by the transfer head 25. Here, the second intermediate stage 31_2 is movable in the Y-axis direction between the first position P1, which is the die D handover position with the transfer head 25, and the third position P3, which is the die D handover position with the bonding head 41. Also, at the second position P2, the second intermediate stage 31_2 performs flux film formation. Note that the flux film formation position may be a position other than the second position P2, for example, the first position P1 or the third position P3.

[0064] In the first face-down bonding method according to this embodiment, a die D is directly placed on the second intermediate stage 31_2 by a transfer head 25 with a flux transfer function. Thereby, flux transfer can be performed during a series of pickup operations of the operation of delivering the die D from the transfer head 25 to the bond head 41.

[0065] Subsequently, the plate 82p of the dipping mechanism 8 in this embodiment will be described with reference to FIG. 8. FIG. 8 is a top view showing a main part of the dipping mechanism shown in FIG. 5.

[0066] On the upper surface (surface) of the bottom of the accommodating portion 82d provided on the plate 82p as a transfer plate, at least on the portion (film forming surface) where the bump Db is immersed, a stable rough surface RS with a surface roughness (arithmetic mean roughness (Ra)) at the nano level is provided. The nano level means 1 nm or more and less than 1000 nm. Ra is preferably 100 to 1000 nm. For example, NAP treatment (registered trademark) may be performed to form irregularities with Ra of 300 to 500 nm on the surface of the accommodating portion 82d. Here, the member of the plate 82p is, for example, SUS (stainless steel).

[0067] Subsequently, the wettability of the rough surface applied to the surface of the accommodating portion 82d of the plate 82p (film forming surface of the plate 82p) with respect to the flux will be described with reference to FIG. 9. FIG. 9(a) is a diagram showing the contact angle when the plate is provided with a rough surface, and FIG. 9(b) is a diagram showing the contact angle when the plate is not provided with a rough surface.

[0068] As shown in FIG. 9(a), when the rough surface RS is formed on the film forming surface of the plate 82p, the contact angle (θB) becomes smaller than 90 degrees due to the decrease in surface tension (capillary action) by the rough surface RS, and the wettability with respect to the flux on the surface is improved. As shown in FIG. 9(b), when the rough surface is not formed on the film forming surface of the plate 82p, the contact angle (θA) becomes larger than 90 degrees. Since the nano-level rough surface has a smaller roughness than the micro-level or higher rough surface, the influence of the irregularities on the thin film of the flux can be reduced. The micro-level or higher means 1 μm or more.

[0069] The film thickness variation of the flux formed on the film-forming surface of the plate 82p will be described with reference to FIGS. 10 and 11. FIG. 10 is a diagram showing the film thickness variation of the flux formed at a gap height of 20 μm for each presence or absence of a rough surface of the plate and viscosity of the flux. FIG. 11 is a diagram showing the film thickness variation of the flux formed at a gap height of 40 μm for each presence or absence of a rough surface of the plate and viscosity of the flux. Here, the gap height is also referred to as the squeegee height and is the height from the surface of the housing portion 82d to the bottom surface of the squeegee device 81.

[0070] (a1) of FIG. 10 and (a1) of FIG. 11 show the case where there is no rough surface on the film-forming surface of the plate 82s and the viscosity of the flux is 10 Pa·s. (a2) of FIG. 10 and (a2) of FIG. 11 show the case where there is a rough surface on the film-forming surface of the plate 82s and the viscosity of the flux is 10 Pa·s. The target film thickness range (TFTR) in (a1) and (a2) of FIG. 10 is 13 μm ± 2 μm. The target film thickness range (TFTR) in (a1) of FIG. 11 and (a2) of FIG. 10 is 25 μm ± 5 μm.

[0071] (b1) of FIG. 10 and (b1) of FIG. 11 show the case where there is no rough surface on the film-forming surface of the plate 82s and the viscosity of the flux is 25 Pa·s. (b2) of FIG. 10 and (b2) of FIG. 11 show the case where there is a rough surface on the film-forming surface of the plate 82s and the viscosity of the flux is 25 Pa·s. The target film thickness range (TFTR) in (b1) and (b2) of FIG. 10 is 12 μm ± 2 μm. The target film thickness range (TFTR) in (b1) of FIG. 11 and (b2) of FIG. 10 is 26 μm ± 5 μm.

[0072] (c1) of FIG. 10 and (c1) of FIG. 11 are the cases where there is no rough surface on the film-forming surface of the plate 82s and the viscosity of the flux is 33 Pa·s. (c2) of FIG. 10 and (c2) of FIG. 11 are the cases where there is a rough surface on the film-forming surface of the plate 82s and the viscosity of the flux is 33 Pa·s. The target film thickness range (TFTR) in (c1) of FIG. 10 and (c2) of FIG. 10 is 15 μm ± 2 μm. The target film thickness range (TFTR) in (c1) of FIG. 11 and (c2) of FIG. 10 is 27 μm ± 5 μm.

[0073] As shown in FIGS. 10 and 11, in any case of the viscosity of the flux and the gap height, when there is no rough surface on the film-forming surface of the plate 82p, the measured value is smaller than the target film thickness range (set value). Also, the variation with respect to the set value is large. When there is a rough surface on the film-forming surface of the plate 82p, the measured value is almost within the target film thickness range. Also, the film thickness variation is reduced compared to the case where there is no rough surface.

[0074] It is presumed that the flux is pulled by the surface tension on the inner peripheral surface of the film-forming surface or is pulled by the squeegee, and as a result, there is a tendency for it to be smaller than the set value near the center of the film-forming surface. On the other hand, when the film-forming surface is roughened, a surface resistance that resists the surface tension etc. is generated at the interface between the rough surface and the flux, and since the flux cannot flow, it is presumed that the tendency for the film thickness to become thinner is weakened.

[0075] The film thickness variation when the target film thickness range is 5 μm ± 20% will be described with reference to FIGS. 12 and 13. FIG. 12 is a diagram showing the film thickness variation of the flux when the viscosity of the flux is 10 Pa·s. FIG. 13 is a diagram showing the film thickness variation of the flux when the viscosity of the flux is 33 Pa·s.

[0076] As shown in Fig. 12, the film thickness at a1 is 4.1 μm, the film thickness at a2 is 4.5 μm, and the film thickness at a3 is 4.3 μm. Also, the film thickness at b1 is 4.5 μm, the film thickness at b2 is 4.9 μm, and the film thickness at b3 is 5.1 μm. The film thickness at c1 is 4.8 μm, the film thickness at c2 is 5.0 μm, and the film thickness at c3 is 4.9 μm. The film thicknesses at nine locations (a1, a2, a3, b1, b2, b3, c1, c2, c3) are from 4.1 to 5.1 μm and are within 5 μm ± 20%.

[0077] As shown in Fig. 13, the film thickness at a1 is 4.1 μm, the film thickness at a2 is 4.6 μm, and the film thickness at a3 is 4.2 μm. Also, the film thickness at b1 is 4.8 μm, the film thickness at b2 is 5.1 μm, and the film thickness at b3 is 5.3 μm. The film thickness at c1 is 5.1 μm, the film thickness at c2 is 5.4 μm, and the film thickness at c3 is 5.0 μm. The film thicknesses at nine locations (a1, a2, a3, b1, b2, b3, c1, c2, c3) are from 4.1 to 5.4 μm and are within 5 μm ± 20%.

[0078] For each film formation of the flux, the film thickness of the flux is measured using a film thickness measuring device 91. The film thickness measurement of the flux will be described with reference to Figs. 14 and 15. Fig. 14 is a diagram for explaining the film thickness measurement using a laser displacement meter. Fig. 15 is a diagram for explaining that the problems shown in Fig. 14 are solved in the embodiment.

[0079] As shown in Fig. 14, a laser displacement meter, which is an example of the film thickness measuring device 91, irradiates, for example, incident light (IL) of laser light onto a film OFM as an object to be measured, measures the reflected light with a sensor such as a CCD (Charge Coupled Device), and measures the thickness of the film OFM based on the distance (h) between the peaks of the received light amount (ALR) of the reflected light.

[0080] As shown on the left side of FIG. 14, when the formed film is opaque, the film thickness (h) of the opaque film OFM is measured by the reflected light (RL) reflected by the incident light (IL) on the object surface before the film is formed and the surface reflected light (SRL) reflected by the incident light (IL) on the surface of the formed opaque film OFM.

[0081] However, as shown on the right side of FIG. 14, when the formed film is transparent, since the refracted reflected light (RRL), which is the light reflected and refracted by the incident light (IL) at the bottom surface of the formed transparent film TFM, is received, it is difficult to separate the surface reflected light (SRL) and the refracted reflected light (RRL). Therefore, an incorrect measurement occurs in measuring the film thickness (h’) based on the refracted reflected light (RRL).

[0082] On the surface of a metal such as SUS (stainless steel), the incident light is specularly reflected (easy to reflect). On the other hand, as shown in FIG. 15, when the surface of the metal is subjected to a roughening treatment, the incident light is diffusely reflected (difficult to reflect) on the rough surface. As a result, the amount of received refracted reflected light (RRL) becomes smaller than the amount of received surface reflected light (SRL) reflected on the surface of the transparent film TFM, and it becomes easier to separate the surface reflected light (SRL) and the refracted reflected light (RRL).

[0083] According to the embodiment, aggregation of a low-viscosity flux with low wettability can be prevented, and a more uniform film thickness can be formed even with a thin film (5 μm or less). Thereby, the flux can be transferred to bumps with a bump diameter of φ10 to 30 μm.

[0084] In addition, a transfer plate for a thin film can be created from a material with low lipophilicity with respect to a flux such as SUS. Also, removal of the old flux on the transfer plate becomes easier compared to a rough surface with a roughness of micro level or more. Also, a thin flux film can be stably spread by a squeegee mechanism. Also, film thickness measurement becomes easy. Also, a semiconductor product with a narrow bump pitch can be stably manufactured.

[0085] <Modification Example> Hereinafter, several representative modifications of the embodiments will be exemplified. In the description of the following modifications, the same reference numerals as those in the above-described embodiments may be used for portions having the same configurations and functions as those described in the above-described embodiments. And, regarding the description of such portions, the description in the above-described embodiments may be appropriately incorporated within a technically consistent range. Further, a part of the above-described embodiments and all or part of a plurality of modifications may be appropriately and combinatorially applied within a technically consistent range.

[0086] (First Modification) The plate 82p of the dipping mechanism 8 in the first modification will be described with reference to FIGS. 16 and 17. FIG. 16 is a top view showing a main part of the dipping mechanism in the first modification. FIG. 17(a) is a top view within the broken line A shown in FIG. 16, and FIG. 17(b) is a cross-sectional view taken along the line B-B shown in FIG. 16.

[0087] As shown in FIG. 16, the bottom surface of the accommodating portion 82d provided in the plate 82p as a transfer plate is provided with a stable rough surface RS having a surface roughness (arithmetic mean roughness (Ra)) at the nanolevel at least at the location where the bump Db is immersed. For example, as shown in FIGS. 17(a) and 17(b), the rough surface RS forms continuous grooves at the nanolevel in a direction along the direction (Y-axis direction) in which the plate 82p moves in the squeegee operation of the dipping mechanism 8, for example, by a shaper method. The rough surface RS is more preferably a continuous groove having a direction of a component along the direction in which the flux spreads. That is, as shown in FIG. 16, the rough surface RS forms continuous grooves along a direction including a component in the X-axis direction in addition to the component in the Y-axis direction at two corner portions of the accommodating portion 82d located on the side far from the squeegee device 81. The two corner portions of the accommodating portion 82d located on the side close to the squeegee device 81 may form continuous grooves only along the Y-axis direction, or may form continuous grooves along a direction including a component in the X-axis direction in addition to the component in the Y-axis direction. The grooves formed on the surface of the bottom surface of the accommodating portion 82d have, for example, Ra of 300 to 500 nm. Here, the member of the plate 82p is, for example, SUS.

[0088] According to the first modification example, grooves in one direction parallel to the squeegee operation reduce the surface tension (capillary action), and further enhance the mobility of the liquid in the grooves due to the squeegee operation. As a result, the extension of the flux by the squeegee operation can be improved, and the thin film formation can be performed more stably. Further, when continuously applying the flux to the transfer plate (dipping plate), the squeegee operation enables efficient discharge of the deteriorated flux applied to the front in the grooves, including the deteriorated flux, and product defects caused by foreign substances or the like due to the deteriorated flux can be reduced.

[0089] (Second Modification Example) The plate 82p of the dipping mechanism 8 in the second modification example will be described with reference to FIG. 18. FIG. 18(a) is a top view of a portion corresponding to the inside of the broken line A shown in FIG. 16, and FIG. 18(b) is a cross-sectional view of a portion corresponding to the B-B line shown in FIG. 16.

[0090] The rough surface RS may form continuous polishing grooves at the nano level in the direction along the direction (Y-axis direction) in which the plate 82p moves in the squeegee operation of the dipping mechanism 8. The grooves formed on the surface of the bottom of the accommodating portion 82d have, for example, a Ra of 300 to 500 nm. Here, the member of the plate 82p is, for example, SUS.

[0091] As described above, the disclosure made by the present inventors has been specifically described based on the embodiments and modification examples. However, it goes without saying that the present disclosure is not limited to the above embodiments and modification examples, and various changes are possible.

[0092] For example, in the embodiment, an example in which the squeegee device 81 is fixed and the plate 82p is moved to form a flux film has been described. However, it is sufficient that the squeegee device 81 moves relative to the plate 82p, and the plate 82p may be fixed and the squeegee device 81 may be moved to form a flux film.

[0093] In addition, in the modification example, an example of providing a groove in one direction parallel to the squeegee operation was described. However, the direction in which the groove extends only needs to have a component in the direction parallel to the squeegee operation. For example, it may extend in a direction at an angle other than 90 degrees, preferably 45 degrees or less, more preferably an angle close to 0 degrees, with respect to the squeegee operation direction, or it may extend in a zigzag shape.

[0094] Alternatively, the transfer plate may be circular and the squeegee may be rotated. In this case, concentric spiral grooves are formed on the transfer plate to form a thin film of flux. The squeegee may be fixed and the transfer plate may be rotated.

[0095] Also, the squeegee height may be made variable. Thereby, when forming the thin film of flux, the height of the squeegee can be adjusted based on the measured film thickness, and it becomes possible to always perform the process with an appropriate film thickness. When discharging the deteriorated flux, the squeegee height is narrowed. Thereby, the dischargeability with respect to the flux in the nano-level rough surface (including grooves) of the transfer plate can be further increased.

[0096] Also, it may be possible to easily remove the transfer plate. Thereby, the cleaning of the transfer plate becomes easy. In addition, even when the transfer plate is removed and cleaned, the cleaning property is high because the depth of the nano-level rough surface of the holes is shallow.

[0097] Also, when cleaning the transfer plate, the squeegee may be operated while discharging cleaning alcohol, which is a solvent for the flux, from the squeegee. Thereby, the cleaning liquid can be physically spread over the nano-level rough surface with a shallow depth, and the cleaning efficiency can be improved.

[0098] Also, ultrasonic waves (vibrations) may be applied during the formation of the thin film of flux. However, they are not applied during transfer. By the squeegee operation, the partially thickly coated portion can be smoothed, the free energy of the transfer plate surface is improved, and the wettability is improved.

[0099] Also, due to the structure of the transfer plate, nano-level continuous grooves may be arranged in a direction to guide the flux to positions where the flux is difficult to spread. This can improve the wettability as a whole and also guide the flux to positions where the flux is difficult to spread to perform film formation.

[0100] In addition, in the embodiment, although an example of a flip chip bonder used in the manufacture of FOPLP has been described, it can also be applied to a fan out wafer level package (FOWLP).

Description of Reference Numerals

[0101] 8... Dipping mechanism (dipping device) 81... Squeegee device 82p... Plate RS... Rough surface

Claims

1. A squeegee device, A plate for forming a flux, Comprising, The surface of the plate has a rough surface with an arithmetic mean roughness at the nanometer level, A dipping device configured to relatively move the squeegee device and the plate and supply the flux from the squeegee device to the rough surface of the plate.

2. In the dipping device according to Claim 1, The dipping device wherein the arithmetic mean roughness of the rough surface is 100 nm or more and 1000 nm or less.

3. In the dipping device according to Claim 1, The dipping device wherein the rough surface is a continuous groove having a direction of a component along the direction in which the flux spreads.

4. In the dipping device according to Claim 1, The dipping device wherein the rough surface is a continuous groove having a direction of a component along the relative movement direction of the squeegee device and the plate.

5. In the dipping device according to Claim 1, The dipping device wherein the height from the surface of the plate to the bottom surface of the squeegee device is variable.

6. A dipping device comprising a squeegee device and a plate for forming a flux, wherein the surface of the plate has a rough surface with an arithmetic mean roughness at the nanometer level, the squeegee device and the plate are relatively moved, and the flux is supplied from the squeegee device to the rough surface of the plate, And a control device for controlling the dipping device A die bonding device comprising.

7. In the die bonding device according to Claim 6, The die bonding device wherein the control device is configured to immerse the bumps of the die in the flux on the plate.

8. In the die bonding device according to Claim 6, The die bonding device wherein the control device is configured to fix the squeegee device and move the plate to form the flux on the plate.

9. In the die bonding device according to Claim 8, Furthermore, a die bonding device comprising a film thickness gauge for measuring the film thickness of the formed flux.

10. In the die bonding device according to Claim 9, The die bonding device wherein the film thickness gauge is a laser displacement meter.

11. In the die bonding device according to Claim 9 or 10, The control device is a die bonding apparatus configured to adjust the film thickness of the flux for film formation based on the film thickness of the flux measured by the film thickness gauge.

12. A flux film formation step of forming a flux for transferring to the bumps of a die having bumps on a plate having a rough surface with a nano-level arithmetic mean roughness on its surface, A flux transfer step of picking up the die and immersing the bumps in the flux, A method for manufacturing a semiconductor device including the above steps.

13. In the method for manufacturing a semiconductor device according to claim 12, Furthermore, after the flux film formation step, a method for manufacturing a semiconductor device including a film thickness measurement step of measuring the film thickness of the formed flux.

Images