JP2015070096A - Droplet coating device and droplet coating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a droplet coating device and a droplet coating method capable of suppressing the number of manufacturing steps and the manufacturing cost.SOLUTION: A droplet coating device 1 includes a coating head 4 as a coating section for discharging the droplets of coating liquid toward a recess formed in a substrate W to be coated, and a control section 5 for controlling the coating head 4 to supply the coating liquid of larger amount than the capacity of the recess to the recess, and to supply the coating liquid of such amount as not flowing over an annular wall to the recess, in a state where the coating liquid is dry to form the annular wall on the substrate W around the recess.

Description

  Embodiments described herein relate generally to a droplet coating apparatus and a droplet coating method.

  Semiconductor packages (semiconductor devices) are used in various electronic devices such as computers, portable information terminals, and communication devices. Due to demands for miniaturization and higher density of these semiconductor packages, BGA (Ball Grid Ally) and CSP (CSP) are used. Surface mount technology such as Chip Size / Scale Package has been put into practical use. In this surface mounting technology, solder (solder) bumps that function as external connection terminals are used, and a semiconductor package is mounted on a substrate by flip chip mounting.

  As a method for forming the above-described solder bump, there are a method of mounting a solder ball on a substrate, a method of printing a solder paste, a plating method of closely attaching solder, and the like. In the method of mounting a solder ball, a flux is applied to each electrode of a base material, a solder ball is mounted on the flux, and then the solder ball is melted in a reflow furnace to form a solder bump. In the method of printing the paste, the paste is applied to each electrode of the substrate through a mask, and the paste is melted in a reflow furnace to form solder bumps. In the plating method, a bump pattern is formed by a lithography technique, and this is plated to form a solder bump.

JP 2004-228375 A

  However, in the above-described method of mounting solder balls, two processes, a process of applying a flux to a base material and a process of mounting solder balls, are required before the reflow process, which increases the number of manufacturing processes. Further, the above-described method for printing the paste requires a mask, and the plating method requires a lithography process. Therefore, the process and the apparatus are complicated, and both methods increase the manufacturing cost. For this reason, it is required to suppress the number of manufacturing steps and the manufacturing cost.

  The problem to be solved by the present invention is to provide a droplet applying apparatus and a droplet applying method capable of suppressing the number of manufacturing steps and manufacturing costs.

  A droplet coating apparatus according to an embodiment of the present invention supplies a coating unit that discharges droplets of a coating liquid toward a recess formed in an object to be coated, and a coating liquid in an amount larger than the volume of the recess. In such a state that the coating liquid is dried so that the supplied coating liquid forms an annular wall on the coating object around the recess, an amount of the coating liquid that does not overflow from the annular wall is supplied to the recess. A control unit for controlling the coating unit.

  A droplet coating method according to an embodiment of the present invention uses a coating unit that discharges droplets of a coating liquid toward a recess formed in an object to be coated, and applies a larger amount of coating liquid to the recess than the volume of the recess. A step of supplying, a step of drying the coating solution so that the coating solution supplied to the recess forms an annular wall on the coating object around the recess, and a coating solution on the coating object around the recess And a step of supplying, to the recess, an amount of coating liquid that does not overflow from the annular wall by using the coating part in a state where the annular wall is formed.

  According to the present invention, the number of manufacturing steps and manufacturing costs can be suppressed.

It is a figure which shows schematic structure of the droplet coating device which concerns on 1st Embodiment. It is sectional drawing which shows schematic structure of the coating head which concerns on 1st Embodiment. It is a 1st process sectional view for explaining the application process concerning a 1st embodiment. It is a 2nd process sectional view for explaining the application process concerning a 1st embodiment. It is a 3rd process sectional view for explaining the application process concerning a 1st embodiment. It is a 4th process sectional view for explaining the application process concerning a 1st embodiment. It is a 5th process sectional view for explaining the application process concerning a 1st embodiment. It is a 6th process sectional view for explaining the application process concerning a 1st embodiment. It is a 7th process sectional view for explaining the application process concerning a 1st embodiment. It is an 8th process sectional view for explaining the application process concerning a 1st embodiment. It is a 9th process sectional view for explaining the application process concerning a 1st embodiment. It is a 10th process sectional view for explaining the application process concerning a 1st embodiment. It is a 1st process sectional view for explaining the application process concerning a 2nd embodiment. It is a 2nd process sectional view for explaining the application process concerning a 2nd embodiment. It is a 3rd process sectional view for explaining the application process concerning a 2nd embodiment. It is a 4th process sectional view for explaining the application process concerning a 2nd embodiment. It is a 5th process sectional view for explaining the application process concerning a 2nd embodiment. It is a 6th process sectional view for explaining the application process concerning a 2nd embodiment. It is a 7th process sectional view for explaining the application process concerning a 2nd embodiment. It is an 8th process sectional view for explaining the application process concerning a 2nd embodiment.

(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the droplet applying apparatus 1 according to the first embodiment of the present invention has a base material W as an application target in a horizontal state (in FIG. 1, a state along the X axis direction and the Y axis direction). ), A stage transport unit 3 that transports the stage 2 in the X-axis direction, and a coating head 4 that ejects droplets (including droplets) toward the coating surface of the substrate W on the stage 2. And a control unit 5 that controls each unit.

  The stage 2 is provided on the stage transport unit 3 and is formed to be movable in the X-axis direction. The mounting surface of the stage 2 is flat, and the substrate W is placed on the mounting surface and fixed by a mechanism such as an electrostatic chuck or an adsorption chuck or by its own weight.

  The stage transport unit 3 supports the stage 2 and guides and moves the supported stage 2 in the X-axis direction. The stage conveyance unit 3 is electrically connected to the control unit 5 and is driven according to control by the control unit 5. For example, a feed screw type moving mechanism using a servo motor as a driving source or a linear motor type moving mechanism using a linear motor as a driving source can be used as the stage transport unit 3. The stage transport unit 3 functions as a moving device that relatively moves the stage 2 and the coating head 4 along the coating surface of the substrate W on the stage 2.

  The coating head 4 functions as a coating unit that discharges a solution, which is a coating solution contained therein, to the outside as a plurality of droplets. The coating head 4 is formed to be movable in the Y-axis direction, and is provided on a support member such as a portal column straddling the stage 2 and the stage transport unit 3 via a head transport unit (both not shown). ing. In addition, as a head conveyance part, it is possible to use a screw type moving mechanism, a linear motor type moving mechanism, etc. like the above-mentioned, for example. This head transport unit also functions as a moving device that relatively moves the stage 2 and the coating head 4 along the coating surface of the substrate W on the stage 2.

  The above-described coating head 4 is movable in the Y-axis direction, but is not limited to this. If the stage 2 and the coating head 4 are relatively moved in the coating region of the substrate W on the stage 2. For example, the stage 2 may be moved in the X axis direction and the Y axis direction by fixing the coating head 4, and conversely, the stage 2 is fixed and the coating head 4 is moved in the X axis direction and Y direction. The stage 2 and the coating head 4 may be moved in the X-axis direction and the Y-axis direction, respectively.

  Here, the solution as the coating liquid is composed of a solute such as a conductive substance (for example, metal) or a dispersant (for example, an organic substance) and a volatile solvent for dissolving (dispersing) the solute. When the droplets of the solution land on the surface of the substrate W and the solvent is completely volatilized from the solution, solutes such as a conductive substance and a dispersant remain. In addition, as a metal, it is possible to use tin, gold | metal | money, silver, etc., for example.

  As shown in FIG. 2, the coating head 4 includes a nozzle plate 11 having a plurality of discharge holes 11a for discharging droplets and a plurality of liquid chambers 12a communicating with the discharge holes 11a, and nozzles thereof. A head main body 12 to which the plate 11 is attached, a flexible plate 13 provided between the nozzle plate 11 and the head main body 12 to change the volume of each liquid chamber 12a, and the flexible plate 13 are deformed. A plurality of piezoelectric elements 14 and a piezoelectric element driving unit 15 that drives the piezoelectric elements 14 are provided.

  The nozzle plate 11 is formed with a plurality of ejection holes 11a arranged in a straight line at predetermined pitches (predetermined intervals) in the longitudinal direction. The coating head 4 is provided on the support member so that the arrangement direction of the discharge holes 11a can be inclined by a predetermined angle with respect to the Y-axis direction in FIG. For example, the coating head 4 is supported by a rotation mechanism (not shown) so as to be rotatable in the θ direction (rotation direction along the XY plane in FIG. 1), and by the rotation mechanism, only a predetermined angle with respect to the Y-axis direction. Tilted. By changing the predetermined angle, it is possible to adjust the interval between the droplets arranged in the Y-axis direction on the substrate W, that is, the coating pitch in the Y-axis direction.

  In addition to each liquid chamber 12a for storing the solution, the head main body 12 communicates with the liquid chamber 12a via a branch pipe (not shown) and one end of the main pipe 12b. A liquid supply pipe 12c and a drain pipe 12d communicating with the other end of the main pipe 12b are formed. The liquid supply line 12c is a flow path for supplying the solution from the solution tank to the main line 12b, and is connected to the solution tank via a supply pipe such as a tube or a pipe. The drainage pipe 12d is a flow path for returning the solution that has passed through the main pipe 12b to the solution tank, and is connected to the solution tank via a discharge pipe such as a tube or a pipe.

  The flexible plate 13 is a plate member for increasing or decreasing the volume of each liquid chamber 12a due to the deformation. The flexible plate 13 is attached to the head body 12 so as to be able to bend and deform, and functions as a wall portion of each liquid chamber 12a. The head body 12 is formed in a rectangular frame shape, and the lower surface side opening portion is closed by the flexible plate 13. The flexible plate 13 is covered with the nozzle plate 11, and each liquid chamber 12 a is formed between the nozzle plate 11 and the flexible plate 13.

  Each piezoelectric element 14 is fixed to the flexible plate 13 so as to face each liquid chamber 12a. These piezoelectric elements 14 are electrically connected to the piezoelectric element driving unit 15 and are driven by power supply from the piezoelectric element driving unit 15. When the piezoelectric element 14 is driven to expand and contract, a part of the flexible plate 13 corresponding to the driven piezoelectric element 14 is deformed, so that the volume of the liquid chamber 12a increases or decreases according to the deformation, and the liquid chamber 12a A droplet is ejected from the communicating ejection hole 11a. This piezoelectric element 14 functions as a drive element.

  The piezoelectric element driving unit 15 is a device that is electrically connected to the control unit 5 and can apply a voltage to each piezoelectric element 14 in response to a control signal from the control unit 5. The piezoelectric element driving unit 15 individually drives each piezoelectric element 14 in accordance with a control signal from the control unit 5, and ejects droplets individually from each ejection hole 11 a of the coating head 4.

  The coating head 4 having such a configuration allows the solution in each liquid chamber 12a to be discharged from the corresponding discharge hole 11a by deformation of the flexible plate 13 in response to application of a driving voltage to each piezoelectric element 14 by the piezoelectric element driving unit 15. Extrude and eject as droplets. Before the discharge, each liquid chamber 12a is filled with the solution.

  Returning to FIG. 1, the control unit 5 includes a microcomputer that controls each unit such as the stage conveyance unit 3 and the coating head 4, and also a storage unit (not shown) that stores coating information and various programs related to coating. It has. Here, the application information includes a predetermined application pattern such as a dot pattern, driving voltage of the application head 4, information on the discharge frequency (discharge timing), and the moving speed (application speed) of the substrate W.

  The control unit 5 controls the stage transport unit 3 and the coating head 4 based on the coating information, and moves toward the substrate W on the stage 2 while relatively moving the substrate W on the stage 2 and the coating head 4. Then, droplets of the solution are intermittently ejected from the respective ejection holes 11 a of the coating head 4, and a coating operation for sequentially coating the dot rows of the droplets on the coating target region on the substrate W is performed. For example, while the stage 2 is moved in the X-axis direction, scanning coating is performed on the substrate W on the stage 2, and after one scanning coating, the coating head 4 is moved to a predetermined pitch in the Y-axis direction (for example, the Y-axis direction). And the stage 2 is moved again in the X-axis direction to perform scanning coating on the substrate W on the stage 2. This scanning application is repeated, and the application to the entire application target area on the substrate W is performed.

  Further, the control unit 5 controls the driving of each piezoelectric element 14 via the piezoelectric element driving unit 15 provided in the coating head 4, and each piezoelectric element 14 at a predetermined ejection timing based on a predetermined driving voltage, ejection frequency, and the like. A drive voltage is applied to. Note that the droplet discharge amount can be adjusted by changing the drive voltage. Further, by changing the ejection frequency and the moving speed of the substrate W, the interval between the droplets arranged in the X-axis direction (the moving direction of the substrate W) on the substrate W, that is, the coating pitch in the X-axis direction is adjusted. It is possible.

  Next, a coating operation (coating method) related to the formation of the conductive bumps of the above-described droplet coating apparatus 1 will be described. First, the base material W to be coated is described, and then the coating process is described. Note that the control unit 5 of the droplet applying apparatus 1 executes the applying process based on various programs.

  As shown in FIG. 3, the base material W to be coated is laminated so that a substrate 21 such as a wafer, an electrode (electrode pad) 22 formed on the substrate 21, and the electrode 22 are exposed. And an insulating layer (for example, a resin layer) 23. The insulating layer 23 has a recess (also called a bank) 23a having the electrode 22 on the bottom surface. The opening of the recess 23a has, for example, a round shape in plan view, and the inner wall of the recess 23a is gradually inclined so that the opening diameter decreases toward the bottom surface. However, the shape of the recess 23a is not particularly limited.

  In FIG. 3, only one electrode 22 and one recess 23a are shown, but there are actually a plurality of each. For example, a plurality of electrodes 22 are provided in a matrix (matrix) on the substrate 21, and a plurality of recesses 23 a are provided in a matrix according to the arrangement of the electrodes 22 so that the electrodes 22 are not covered with the insulating layer 23. It has been. A solution is supplied by the coating head 4 to the plurality of recesses 23a arranged in a matrix. At this time, the coating head 4 discharges the solution at a time to the plurality of recesses 23a within a range where droplets of the solution can be supplied. It will be. Also in the following drawings, for simplification of explanation, the electrodes 22 and the recesses 23a are shown one by one, and the coating process for the substrate W will be described based on these drawings.

  In the coating process according to the first embodiment, first, a droplet of a solution is ejected from the coating head 4 toward the recess 23a (see FIG. 3) of the substrate W, and a predetermined amount of solution A1 larger than the volume of the recess 23a. Is supplied to the recess 23a of the substrate W. As a result, as shown in FIG. 4, the solution A1 supplied to the recess 23a overflows from the recess 23a and spreads over the insulating layer 23 around the recess 23a. In addition, since it is necessary to avoid the solutions leaking from the adjacent recesses 23a from contacting each other, the above-described predetermined amount is an amount in which the solutions leaking from the adjacent recesses 23a do not contact each other, for example, the recesses 23a. It is set to less than twice the capacity.

  In the process in which the solution A1 is gradually dried after the supply (the process in which the volatile solvent of the solution A1 is volatilized), convection (for example, Marangoni convection) is generated in the solution A1 supplied to the recess 23a. As a result, the solute flows and gathers on the insulating layer 23 around the recess 23a, and moves downward due to gravity and gathers in layers along the inner walls of the electrode 22 and the recess 23a. As a result, as shown in FIG. 5, an annular wall B1 surrounding the opening of the recess 23a is formed on the insulating layer 23 around the recess 23a, and an underlying layer connected to the annular wall B1 is formed in the recess 23a. Formed on the inner wall and the electrode 22.

  The solution that forms the annular wall B1 and the base layer is not in a state in which the volatile solvent is completely evaporated, but in a state in which the volatile solvent is contained in a small amount other than the solute, and the flow is stopped semi-cured. It is in a state. In addition, since the volatility of the solvent used normally is high, after a droplet reaches the recessed part 23a, it will be in a semi-hardened state in several seconds.

  Here, when a predetermined amount of solution is supplied to the concave portion 23a of the substrate W, it may be supplied by a single droplet or a plurality of droplets. In the supply by a plurality of droplets, a smaller amount of droplets is continuously ejected, and the total amount of these droplets is set to a predetermined amount. When supplying with a plurality of droplets, it is necessary to land the next droplet before the landed droplet becomes a semi-cured state. For this reason, the ejection frequency is set higher as the volatility increases, for example, according to the volatility of the solution.

  Next, as shown in FIG. 5, an annular wall B1 is formed on the insulating layer 23 around the recess 23a, and a base layer connected to the annular wall B1 is formed on the electrode 22 and the inner wall of the recess 23a. In this state, droplets of the solution are discharged from the coating head 4 toward the recess 23a of the substrate W, and an amount of the solution A2 that does not overflow from the annular wall B1 is supplied to the recess 23a. As a result, as shown in FIG. 6, the solution A2 is stored on the annular wall B1 and the underlying layer without overcoming the annular wall B1. For this reason, the solution A2 does not overflow and spread on the insulating layer 23.

  Thereafter, in the same way as described above, convection is generated in the solution A2 supplied to the recess 23a in the process of gradually drying the solution A2 (process in which the volatile solvent of the solution A2 volatilizes). As described above, the solute flows and collects on the insulating layer 23 around the recess 23a, and also collects in the recess 23a by gravity. At this time, the mutual solvent of the solution A2 and the solution A1 are mixed, and the solute of the solution A2 is accumulated so as to be stacked on the solute of the solution A1. For this reason, the recess 23a is filled with the solution, and the height of the annular wall B1 is also increased.

  In order to increase the height of the annular wall B1 to a desired height, supplying an amount of solution that does not overflow from the annular wall onto the recess 23a is repeated a predetermined number of times. The predetermined number of times of solution supply is performed at a predetermined interval, and this predetermined interval is an interval at which the next supply is executed when the solution after supply is in a semi-cured state. When such a predetermined number of times of solution supply is performed, as shown in FIG. 7, an annular wall B2 (higher than the wall B1) having a desired height and width is formed, and the recess 23a is filled with the solution.

  The steps so far are the wall forming steps for forming the desired wall B2. In order to raise the wall B1 by positively generating convection in the solution A1 supplied to the recess 23a, both or one of the substrate W and the coating head 4 is moved by heating means such as a hot plate or a heater. Heat may be applied to the solution on the substrate W or the solution in the coating head 4.

  Next, after the above-described wall forming step, as shown in FIG. 7, an annular wall B2 is formed on the insulating layer 23 around the recess 23a, and the recess 23a is filled with a semi-cured solution. In this state, droplets of the solution are discharged from the coating head 4 toward the recess 23a of the substrate W, and an amount of the solution A3 that does not overflow from the annular wall B2 is supplied to the recess 23a. As a result, as shown in FIG. 8, the solution A3 is dammed by the annular wall B2, and is stored between the annular walls B2. For this reason, the solution A3 gets over the annular wall B2 and does not overflow and spread on the insulating layer 23. At this time, the solution A3 has a substantially semi-elliptical spherical shape (plano-convex shape of the lens).

  Thereafter, in the same manner as described above, the convection generated in the solution A3 supplied to the recess 23a in the process of gradually drying the solution A3 (process in which the volatile solvent of the solution A3 is volatilized) is as described above. As shown in FIG. 9, the semi-elliptical spherical solution A3 is gradually smaller as the solvent evaporates while maintaining its shape. At this time, the mutual solvent of the solution A3 and the previous solution are mixed, and the solute of the solution A3 is accumulated so as to be stacked on the solute of the previous solution. The height of the annular wall B2 is maintained.

  In order to laminate the solution to a desired height, as shown in FIG. 10, the supply of the solution A4 in an amount that does not overflow from the annular wall B2 to the recess 23a is repeated a predetermined number of times. The predetermined number of times of solution supply is performed at a predetermined interval, and this predetermined interval is an interval at which the next supply is executed when the solution after supply is in a semi-cured state. When the solution is supplied a predetermined number of times and the solution filling the recess 23a is in a semi-cured state, as shown in FIG. 11, the semi-cured solution becomes a substantially semi-spherical shape due to surface tension, and has a desired size. It has become.

  The process so far after the wall forming process is a stacking process in which stacking is repeated to a desired height. By increasing the number of times the solution is supplied (number of times of lamination) in this laminating step, it is possible to reduce the amount of solution supplied at one time and suppress the occurrence of convection in the solution after supply, so that a desired shape is obtained. It becomes easy. In the laminating step, it is desirable that the droplet size is on the order of 20 pl (picoliter), and the flying speed is 10 m / s or less in order to reduce the kinetic energy when laminating the droplets.

  Finally, the base material W after the wall forming step and the laminating step is put into a reflow furnace (reflow apparatus), and the solute on the base material W is melted. As a result, the solvent in the solution is completely volatilized, and the molten solute is attracted by the surface tension to be integrated (the solute fine particles are combined), and as shown in FIG. 12, the desired height and width ( A semicircular conductive bump 24 having a desired aspect ratio is formed.

  In such a manufacturing process, the annular wall B2 surrounding the opening of the recess 23a is formed at a desired height by the wall forming process, and the solution is sequentially supplied onto the recess 23a in the annular wall B2 by the stacking process. In this lamination step, when the solution is dropped inside the annular wall B2, the horizontal flow is blocked by the annular wall B2. Finally, the solute in the solution is melted and integrated by the reflow process, and the conductive bumps 24 are formed on the recesses 23a. Thus, the lamination of the solutions becomes easy, and the conductive bumps 24 having a desired height and width can be easily formed. It is also effective to drop the solution while heating the stage 2 in order to promote drying of the droplet. Further, the viscosity of the solution is 30 mPa · s or more, and the higher the solid content, the shorter the tact.

  As described above, according to the first embodiment, a larger amount of solution is supplied to the recess 23a formed in the substrate W, and then the solution is applied to the substrate W around the recess 23a. In a state where the annular wall B1 or B2 is formed, by supplying an amount of a solution that does not overflow from the annular wall B1 or B2 to the recess 23a, the desired height and width (desired aspect ratio) are obtained. Conductive bumps 24 can be formed. For this reason, as the manufacturing process, two processes of applying the flux to the substrate W and mounting the solder ball are not required before the reflow process, and only one process of the applying process is required. Can be suppressed. Furthermore, as compared with paste printing and plating methods, a mask and a lithography process are not necessary, and the process and apparatus are simplified, so that the manufacturing cost can be suppressed.

(Second Embodiment)
A second embodiment will be described with reference to FIGS.

  The second embodiment is basically the same as the first embodiment. Therefore, in the second embodiment, differences from the first embodiment (application process flow) will be described, and the same parts as those described in the first embodiment will be denoted by the same reference numerals, and the description thereof will also be given. Omitted.

  In the coating process according to the second embodiment, first, a droplet of a solution is ejected from the coating head 4 toward the recess 23a (see FIG. 3) of the substrate W, and a predetermined amount of solution C1 larger than the volume of the recess 23a. Is supplied to the recess 23a of the substrate W. As a result, as shown in FIG. 13, the solution C1 supplied to the recess 23a overflows from the recess 23a and spreads onto the insulating layer 23 around the recess 23a. This spread is a spread of a range in which the solute melted in the reflow process can return from the periphery of the recess 23a to the recess 23a by the surface tension. That is, the predetermined amount is a solution amount larger than the volume of the recess 23a, and the solution that overflows and spreads on the insulating layer 23 around the recess 23a depends on the surface tension when the solute contained in the solution is melted. This is the amount of solution that can return from the periphery of the recess 23a onto the recess 23a. In addition, since it is necessary to avoid the solutions leaking from the adjacent recesses 23a from contacting each other, even if the above-mentioned predetermined amount satisfies the above-described conditions, the solutions leaking from the adjacent recesses 23a are mutually connected. It is set to an amount that does not contact, for example, twice or less the capacity of the recess 23a.

  In the process in which the solution C1 is gradually dried after the supply (process in which the volatile solvent of the solution C1 is volatilized), convection (for example, Marangoni convection) is generated in the solution C1 supplied to the recess 23a. As a result, the solute flows and gathers on the insulating layer 23 around the recess 23a, and moves downward due to gravity and gathers in layers along the inner walls of the electrode 22 and the recess 23a. As a result, as shown in FIG. 14, an annular wall D1 surrounding the opening of the recess 23a is formed on the insulating layer 23 around the recess 23a, and an underlying layer connected to the annular wall D1 is formed in the recess 23a. Formed on the inner wall and the electrode 22. The outer diameter and width of the annular wall D1 are larger than those of the annular walls B1 and B2 according to the first embodiment.

  The solution forming the annular wall D1 and the underlayer is not in a state where the volatile solvent is completely evaporated, but in a state containing the volatile solvent in a small amount other than the solute, as in the first embodiment. It is in a semi-cured state where flow is stopped. Further, when a predetermined amount of solution is supplied to the concave portion 23a of the substrate W, as in the first embodiment, supply by a single drop or supply by a plurality of drops may be used.

  Next, as shown in FIG. 14, an annular wall D1 is formed on the insulating layer 23 around the recess 23a, and a base layer connected to the annular wall D1 is formed on the electrode 22 and the inner wall of the recess 23a. In this state, droplets of the solution are ejected from the coating head 4 toward the recess 23a of the substrate W, and an amount of the solution C2 that does not overflow from the annular wall D1 is supplied to the recess 23a. As a result, as shown in FIG. 15, the solution C2 is stored on the annular wall D1 and the underlying layer without overcoming the annular wall D1. For this reason, the solution C2 does not overflow and spread on the insulating layer 23.

  After that, in the process of gradually drying the solution C2 (the process of volatilization of the volatile solvent of the solution C2) as described above, convection is generated in the solution C2 supplied to the recess 23a. As described above, the solute flows and collects on the insulating layer 23 around the recess 23a, and also collects in the recess 23a by gravity. At this time, the mutual solvents of the solution C2 and the solution C1 are mixed, and the solute of the solution C2 is accumulated so as to be stacked on the solute of the solution C1. For this reason, the recess 23a is filled with the solution, and the height of the annular wall D1 is also increased.

  In order to increase the height of the wall D1 to a desired height, the supply of an amount of the solution that does not overflow from the annular wall to the recess 23a is repeated a predetermined number of times. The predetermined number of times of solution supply is performed at a predetermined interval, and this predetermined interval is an interval at which the next supply is executed when the solution after supply is in a semi-cured state. When such a predetermined number of times of solution supply is performed, as shown in FIG. 16, an annular wall D2 having a desired height and width (higher than the wall D1) is formed, and the recess 23a is filled with the solution. The outer diameter and width of the annular wall D2 are larger than those of the annular walls B1 and B2 according to the first embodiment.

  The steps so far are the wall forming steps for forming the desired wall D2. Note that, in order to positively generate convection in the solution C1 supplied to the recess 23a and raise the wall D1, the substrate W and the substrate W are heated by heating means such as a hot plate or a heater, as in the first embodiment. Both or one of the coating heads 4 may be heated to apply heat to the solution on the substrate W or the solution in the coating head 4.

  Next, after the aforementioned wall forming step, as shown in FIG. 16, an annular wall D2 is formed on the insulating layer 23 around the recess 23a, and the recess 23a is filled with a semi-cured solution. In this state, droplets of the solution are discharged from the coating head 4 toward the recess 23a of the substrate W, and an amount of the solution C3 that does not overflow from the annular wall D2 is supplied to the recess 23a. As a result, as shown in FIG. 17, the solution C3 is dammed by the annular wall D2, and is stored between the annular walls D2. For this reason, the solution C3 does not get over the annular wall D2 and overflow and spread on the insulating layer 23. The solution C3 at this time has a substantially semi-elliptical spherical shape (a plano-convex shape of the lens).

  Thereafter, in the same way as described above, the convection generated in the solution A3 supplied to the recess 23a in the process of gradually drying the solution C3 (the process of volatilizing the volatile solvent of the solution C3) is as described above. As shown in FIG. 18, the shape of the semi-elliptical spherical solution C3 is substantially flat at the top (or concave at the top center), as shown in FIG. At this time, the solvents of the solution C3 and the previous solution are mixed, and the solute of the solution C3 is accumulated so as to be stacked on the solute of the previous solution. The height of the annular wall D2 is maintained.

  In order to stack the solutions to a desired height, as shown in FIG. 19, the supply of the amount of the solution C4 that does not flow down onto the recesses 23a is repeated a predetermined number of times. The predetermined number of times of solution supply is performed at a predetermined interval, and this predetermined interval is an interval at which the next supply is executed when the solution after supply is in a semi-cured state. In addition, the supply amount is gradually reduced for each supply, and an amount of solution that does not flow down is supplied. When the solution is supplied a predetermined number of times and the solution filling the recess 23a is in a semi-cured state, the semi-cured solution has a desired size as shown in FIG.

  The process so far after the wall forming process is a stacking process in which stacking is repeated to a desired height. As in the first embodiment, by increasing the number of times of solution supply (number of times of stacking) in this stacking step, the amount of solution supplied at one time can be reduced, and the occurrence of convection in the solution after supply can be suppressed. Therefore, it becomes easy to obtain a desired shape (for example, a shape in which the upper part is substantially flat or a hollow shape).

  Finally, the base material W after the wall forming step and the laminating step is put into a reflow furnace (reflow apparatus), and the solute on the base material W is melted. As a result, the solvent in the solution is completely volatilized, and the molten solute is attracted by the surface tension to be united (the solute fine particles are united), and has a desired height and width (desired aspect ratio). A semicircular conductive bump 24 is formed (see FIG. 12). At this time, the semi-circular conductive bump 24 having a desired height and width is obtained because the surface tension when the solute contained in the solution is melted returns from the periphery of the recess 23a to the recess 23a (self-alignment). It is possible. Therefore, the conductive bumps 24 can be formed at regular positions by collecting the solutes on the substrate W by self-alignment due to the surface tension of the solutes.

  In such a manufacturing process, the annular wall D2 surrounding the opening of the recess 23a is formed to a desired height and width by the wall forming process, and the solution is sequentially supplied onto the recess 23a in the annular wall D2 by the stacking process. The In this laminating step, when the first solution is dropped inside the annular wall D2, the horizontal flow is blocked by the annular wall D2, and then the solutions are sequentially laminated so as not to flow down. Finally, the solute in the solution is melted by the reflow process, and the surface tension at that time returns from the periphery of the recess 23a to the recess 23a to be integrated, and the conductive bump 24 is formed on the recess 23a. Thus, the lamination of the solutions becomes easy, and the conductive bumps 24 having a desired height and width can be easily formed. Furthermore, in the initial solution supply in the stacking step, for example, it is possible to drop more than twice the volume of the recess 23a, and the throughput can be shortened. As in the first embodiment, it is also effective to drop the solution while heating the stage 2 in order to promote drying of the droplet. Further, the viscosity of the solution is 30 mPa · s or more, and the higher the solid content, the shorter the tact.

  As described above, according to the second embodiment, the same effects as those of the first embodiment can be obtained. In other words, the amount of the recess 23a formed in the base material W overflows the base material W around the recess 23a to form the annular wall D1, and overflows from the recess 23a to the periphery. The solution spread on the insulating layer 23 supplies an amount of solution that can return from the periphery of the recess 23a to the recess 23a by the surface tension when the solute contained in the solution is melted, and then the recess 23a By supplying an amount of solution that does not overflow from the annular wall D1 or D2 to the recess 23a in a state where the annular wall D1 or D2 is formed on the surrounding substrate W, the desired height and Conductive bumps 24 having a width (desired aspect ratio) can be formed. For this reason, as the manufacturing process, two processes of applying the flux to the substrate W and mounting the solder ball are not required before the reflow process, and only one process of the applying process is required. Can be suppressed. Furthermore, as compared with paste printing and plating methods, a mask and a lithography process are not necessary, and the process and apparatus are simplified, so that the manufacturing cost can be suppressed.

  In the first or second embodiment described above, the landing position of the liquid droplet of the solution is set at the center of the bottom surface of the recess 23a. However, the present invention is not limited to this, and a predetermined distance (from the center position) For example, the position may be shifted by several μm). When the diameter of the liquid droplet is equal to or larger than the diameter of the opening of the concave portion 23a, the predetermined distance is a projection image of the liquid droplet discharged from the discharge hole 11a of the coating head 4 and landing on the substrate W, and the concave portion 23a. It is set so that there is a region (air escape region) that does not overlap the opening region. As a result, a state in which the opening of the recess 23a is not blocked when the liquid droplets land on the recess 23a does not occur, and the air in the recess 23a flows out from the air escape area to the outside. It is possible to suppress the remaining. For this reason, it is possible to suppress the deterioration of the bump shape due to residual air and to reliably form the conductive bump 24 having a desired height and width.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  In the above-described embodiment, the solution is composed of a solute such as a conductive substance or a dispersant and a volatile solvent that dissolves the solute. However, the present invention is not limited to this, and a three-dimensional image or the like is formed. It may be a solution composed of other solutes and solvents used for the purpose. When used for this purpose, an image can be formed accurately.

  In the above-described embodiment, the droplet applying apparatus 1 stops the movement of the stage 2 (relative movement between the application head 4 and the stage 2) when discharging the droplet of the solution to the recess 23a. It can be left as it is. For example, when a required amount of solution is supplied to the recess 23a by one drop, the solution is discharged from the nozzle 11a in accordance with the timing when the recess 23a passes under the nozzle 11a of the coating head 4 while the stage 2 is moved. When supplying the required amount of solution with a plurality of drops, the movement of the stage 2 is stopped when the recess 23a reaches just below the nozzle 11a of the coating head 4, and the solution is discharged from the nozzle 11a. A plurality of droplets may be discharged, and the stage 2 may be moved again when the discharge is completed. However, even when a required amount of solution is supplied to the recess 23a by one drop, the movement of the stage 2 may be stopped and the solution may be discharged.

  In addition, a plurality of pre-cured solutions are stacked in each concave portion 23a provided on the base material W, but each layer is formed by supplying a solution for forming the first layer in all the concave portions 23a on the equipment W. After that, a solution for forming the second layer may be supplied so that one layer is formed for each substrate W, and the number of the recesses 23a on the substrate W may be any number of recesses 23a. It is also possible to divide into such groups and form one layer at a time for each group. Whether the solution layer in the temporarily cured state is formed in units of the substrate W or in units of groups including the plurality of recesses 23a is determined depending on whether the solution supplied in the recesses 23a is in a temporarily cured state suitable for stacking. What is necessary is just to determine according to the time required to reach. For example, if it takes several tens of seconds to supply the solution to all the recesses 23a on the substrate W while reaching the pre-cured state suitable for lamination in several seconds, the recesses 23a on the substrate W May be divided into a number of group units capable of supplying the solution in a few seconds, and the wall forming step and the laminating step may be performed in units of the group units.

  Furthermore, the wall forming step and the laminating step may be performed in units of a plurality of recesses 23a that can simultaneously face the nozzles 11a of the coating head 4. That is, the stage 2 is moved so that the recesses 23a located in the first row among the recesses 23a formed in a matrix on the substrate W are positioned below the nozzles 11a row of the coating head 4, and the nozzles are moved at this position. The wall forming process and the laminating process are performed on the plurality of recesses 23a located directly below 11a, and then the stage 2 is moved so that the recesses 23a positioned in the second row are positioned below the nozzles 11a row of the coating head 4 In the same manner as in the first row, the wall forming process and the laminating process are performed on the plurality of recesses 23a located immediately below the nozzle 11a.

  In the above-described embodiment, the drying of the solution is not a state in which the volatile solvent is completely evaporated from the solution, but a state in which the volatile solvent is contained and the flow is stopped. However, the present invention is not limited to this, and the volatile solvent may be completely evaporated. In short, a solution wall is formed around the recess 23a, and the wall forming step and In the reflow process after the lamination process, it is only necessary that the molten solute can be integrated by surface tension.

DESCRIPTION OF SYMBOLS 1 Droplet coating device 4 Coating head 5 Control part 23a Recessed part B1 Wall B2 Wall D1 Wall D2 Wall W Base material

Claims (8)

An application part for discharging droplets of an application liquid toward a recess formed in the application object;
A state in which the coating liquid is dried such that an amount of the coating liquid larger than the volume of the concave portion is supplied to the concave portion, and the supplied coating liquid forms an annular wall on the coating object around the concave portion. And a control unit for controlling the coating unit so as to supply the coating liquid in an amount that does not overflow from the annular wall to the recess,
A droplet applying apparatus comprising:   2. The droplet coating apparatus according to claim 1, wherein the control unit controls the coating unit to repeatedly supply an amount of coating liquid that does not overflow from the annular wall to the concave portion.   The droplet coating apparatus according to claim 2, wherein the application target is a semiconductor wafer, and the coating liquid includes a conductive substance and a volatile solvent.   The amount larger than the capacity of the recess is an amount that forms the annular wall by overflowing the coating solution on the semiconductor wafer around the recess, and the conductive substance contained in the coating solution is melted. The conductive material contained in the coating liquid forming the wall is an amount capable of returning from the periphery of the concave portion to the concave portion depending on the surface tension at the time. Droplet applicator. Supplying an amount of coating liquid larger than the volume of the concave portion to the concave portion using a coating portion that discharges droplets of the coating liquid toward the concave portion formed in the application target;
Drying the coating solution so that the coating solution supplied to the recess forms an annular wall on the coating object around the recess;
Supplying an amount of coating liquid that does not overflow from the annular wall using the coating unit in a state where an annular wall made of the coating liquid is formed on the object to be coated around the recess. When,
A droplet coating method comprising:   6. The droplet coating method according to claim 5, wherein the step of supplying an amount of the coating liquid that does not overflow from the annular wall to the concave portion is repeated.   The droplet application method according to claim 6, wherein the application target is a semiconductor wafer, and the application liquid contains a conductive substance and a volatile solvent.   The amount larger than the capacity of the recess is an amount that forms the annular wall by overflowing the coating solution on the semiconductor wafer around the recess, and the conductive substance contained in the coating solution is melted. The amount of the conductive material contained in the coating liquid that forms the wall can be returned from the periphery of the recess to the recess due to the surface tension at the time. Droplet application method.

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