JP5872409B2 - Metal filling equipment - Google Patents

Description

  The present invention relates to a metal filling apparatus for filling molten metal into a minute space formed on the surface of an object to be processed.

  In the through silicon via technology, there is a demand for a technology in which metal is filled in vias and through holes (microspaces) provided on a semiconductor wafer (object to be processed). If silicon through-electrode technology is used, chip stacking technology using through-electrodes can be developed. Therefore, it is expected to realize a high-functional and high-speed semiconductor system by three-dimensional mounting.

  Conventionally, the techniques of Patent Documents 1 to 3 are known as techniques for filling molten metal into a minute space on a semiconductor wafer.

  Although a specific apparatus configuration is not disclosed in Patent Documents 1 and 2, forced external force (pressure, magnetic force, centrifugal force, press pressure, injection pressure, rolling pressure, etc.) is applied to the molten metal in the vicinity of the minute space. In addition, a metal filling method that can fill a minute space with a hardened metal without generating voids or voids is disclosed.

  Further, in Patent Document 3, molten metal M is supplied to the upper surface of the object 2 disposed in a predetermined gap between the first support 10 and the second support 11, and the surface of the object 2 is A metal filling device is disclosed in which molten metal M is filled or pressurized in a minute space formed in (1) and the pressurized state is maintained until the molten metal M is cured by cooling.

JP 2010-129662 A JP 2010-129995 A JP 2010-283034 A

  According to Patent Documents 1 to 3, it is understood that it is beneficial to apply a forced external force to the filling metal in order to fill the molten metal inside the minute space on the semiconductor wafer without a gap. This is because the molten metal to be filled has the property of going out from the inside of the minute space due to its surface tension.

  However, for example, even if it is considered to use a press pressure as a forced external force, the molten metal is placed inside the minute space on the object to be processed depending on the press member of which material is used and the press pressure is applied to the molten metal. The metal filling state when filling is greatly different.

  For example, when pressing a molten metal using a material having a large surface roughness for the pressing member, the pressed molten metal is fixed not only on the workpiece side but also on the surface on the pressing member side. When the molten metal is cured in this state, the cured metal is bonded to the press member, and as soon as the press member is separated from the object to be processed (opened), the minute space of the object to be processed is removed. There is a problem in that the metal filled in the inside is missing or chipped, resulting in poor filling.

  In the worst case, when the filler metal fixed to both the press member and the filling material is firmly bonded to each other and the bonded press member is separated from the filling material, the force (for example, semiconductor) A situation occurs in which the wafer is broken.

  Further, the pressing member is a member that contacts a molten metal having a temperature equal to or higher than the melting point and applies a pressing force to the molten metal with a force of, for example, several tons. It is practically required to be made of a material that does not deteriorate and has high durability.

  The inventor of the present application, after earnest research, finds the above-mentioned problems uniquely, and in order not to cause poor filling or cracking of the filling material, what kind of material should the press pressure be applied to the molten metal? The present invention was completed after trials using various materials.

  The present invention has been made in view of the above circumstances, and the inside of a minute space formed so as to open on the object to be processed without causing defective filling or cracking of the object to be processed (for example, wafer cracking). An object of the present invention is to provide a metal filling apparatus capable of accurately filling molten metal.

Metal filling apparatus of the present invention, in order to solve the above problems, the object to be processed front surface micro space formed so as to open in the are filled with molten metal supplied onto該被treated The present invention relates to a metal filling apparatus.

In order to solve the above-described problems, a metal filling device according to the present invention includes a holding unit that holds the object to be processed, a cylindrical member that has an internal space, and has one end facing the holding unit. A pressing member that is slidably inserted into the inner space of the cylindrical member and presses the molten metal against the object to be processed; an object to be processed or the holding part that is held by the holding part; and the cylindrical member and then pressurizing and depressurizing device for depressurizing the processing chamber formed in an airtight manner, and the molten metal supply mechanism for supplying molten metal into the processing chamber, a molten metal is supplied into the processing chamber by said pressing member, A pressing mechanism for pressing the molten metal into the minute space, and at least the side of the pressing member facing the object to be processed is made of metal.

  According to this metal filling apparatus, first, an object to be processed in which a minute space is formed on the surface is arranged on the holding portion so that the surface faces the pressing member. One end of the cylindrical member is in contact with the object to be processed or the holding part held by the holding part, and an airtight processing chamber surrounded by the object to be processed or the holding part, the cylindrical member and the pressing member is provided. Is formed. In the case where the specific gravity of the molten metal is larger than the specific gravity of the object to be processed, with the one end of the cylindrical member in contact with the object to be processed, the object to be processed, the cylindrical member and the pressing member By forming the processing chamber, it is possible to prevent the object to be processed from floating above the holding portion when the molten metal is supplied into the processing chamber.

  Next, the gas in the processing chamber is exhausted by the pressure reducing mechanism to reduce the pressure in the processing chamber. Due to the reduced pressure in the processing chamber, the inside of the minute space formed in the object to be processed is also reduced in pressure. Thereafter, the molten metal is supplied into the processing chamber (between the object to be processed and the pressing member) by the molten metal supply mechanism. In addition, when the wettability (affinity) between the molten metal and the object to be processed is good, at this stage, the supplied molten metal is filled into the micro space by its own weight and interfacial tension. When the wettability between the metal and the object to be processed is extremely poor, the molten metal is bounced on the surface of the object to be processed and is not filled in the minute space only by reducing the pressure inside the minute space.

  Next, in the metal filling apparatus, the molten metal supplied into the processing chamber is pressurized by the action of the pressurizing mechanism, and the molten metal is pushed into the minute space. For example, after the processing chamber is completely filled with molten metal, the pressing member is moved toward the object to be processed, and the molten metal supplied into the processing chamber is pressurized by the pressing member, so that a minute space on the object to be processed is obtained. Molten metal is pushed inside. Therefore, even when the wettability between the molten metal and the object to be processed is poor, the molten metal can be filled into the minute space, and the molten metal is supplied into the processing chamber after the processing chamber is decompressed. As a result, generation of voids is reduced. Since the processing chamber is completely filled with the molten metal, the molten metal is not repelled on the object to be processed, and the molten metal spreads uniformly on the object to be processed. Further, in this case, the molten metal that does not completely enter the minute space is pushed back to the molten metal supply mechanism between the workpiece and the pressing member.

  As described above, in the metal filling apparatus, after the processing chamber is depressurized, the molten metal is supplied into the processing chamber, and the pressing member is further moved toward the object to be processed. As a result, the volume of the processing chamber is reduced, in other words, the gap between the object to be processed and the pressing member is narrowed, so that excess molten metal on the object to be processed can be removed from between the object to be processed and the pressing member. Can be pushed out. Therefore, it is possible to prevent a layer made of surplus metal from being formed on the object to be processed.

  In addition, since the volume in the processing chamber is variable by the movement of the pressing member, the volume in the processing chamber can be made extremely small depending on the amount of movement of the pressing member. Most of the excess metal on the object can be pushed away from the object to be processed, and the residue remaining on the object to be processed can be minimized. In the present specification, the residue refers to a layered unnecessary metal portion formed by curing an excess metal that has not been able to enter the inside of the minute space on the object to be processed. The portion is not unnecessary in all cases and may be used as a wiring layer or a contact layer.

  The metal surface of the pressing member is extremely small in surface roughness, and the molten metal does not adhere and can be easily peeled off, so that even after the filling of the molten metal into the workpiece is completed and the metal is cured, The object to be processed is not in a state of being bonded by a hardened metal. Therefore, even if the pressing member is pulled away from the object to be processed after the filling process, the metal filled inside the minute space on the surface of the object to be treated remains inside the minute space, so that there is a problem of pulling out or chipping of the filling metal. In addition, a situation in which the workpiece (for example, a semiconductor wafer) is broken by a force when the pressing member is separated from the workpiece does not occur.

  Since the metal surface of the pressing member is hard and excellent in durability and heat resistance, it hardly deteriorates even when the metal filling process is repeated. Therefore, not only frequent maintenance is required, but even when the surface of the pressing member is cleaned, a simple cleaning means using a brush or the like can be employed without worrying about inadvertently damaging the surface.

  In the above configuration, it is preferable that a pressing mechanism for moving the pressing member forward and backward with respect to the object to be processed held by the holding unit is provided.

  According to said structure, the said pressing member can be advanced / retreated so that it may approach or move away with respect to a to-be-processed object with the pressing mechanism which consists of various cylinders, a motor, etc. Therefore, the pressing member can be freely moved with respect to the object to be processed held by the holding portion by the drive control of the pressing mechanism.

  In the above configuration, it is preferable that a moving mechanism that moves at least one of the holding portion and the cylindrical member in a direction approaching and separating from the other is preferably provided.

  According to said structure, at least one of a holding | maintenance part and a cylindrical member can be moved to the direction which approaches / separates with respect to the other by the effect | action of a moving mechanism. Therefore, the holding portion and one end of the cylindrical member are brought into close contact with each other to realize a sealed structure, or these are separated to open the space between the holding portion and one end of the cylindrical member, and the covered space is covered from the open space. It becomes possible to easily take in and out processed materials and the like.

  In the above configuration, it is preferable that the pressing member is provided with a molten metal sealing portion that confines the molten metal supplied by the molten metal supply mechanism between the pressing member and the surface of the workpiece.

  According to the above configuration, when the molten metal is pressed by the pressing member due to the action of the molten metal sealing portion, the molten metal can be confined between the pressing member and the surface of the workpiece. When moved, it becomes possible to apply a high pressure to the molten metal in the molten metal sealing portion. Therefore, the pressure by the pressing member is effectively applied to the molten metal. In particular, if the molten metal sealing part is made of an elastic body, the molten metal sealing part is deformed so as to be crushed when the pressing member is moved, so that a high pressure can be applied to the entire processing surface of the workpiece. It becomes. Therefore, the molten metal can be filled in the minute space formed on the object to be processed without a gap.

  Further, the pressurizing mechanism may be a pressurized gas supply mechanism that supplies a pressurized gas into the processing chamber. In this way, by supplying the pressurized gas into the processing chamber to which the molten metal has been supplied, the molten metal supplied into the processing chamber can be pressurized with the gas, and the so-called differential pressure filling allows the molten metal to be microspaced. Can be filled inside. Furthermore, the molten metal can be prevented from being bounced on the object to be processed by pressurizing the molten metal with gas.

  Moreover, in said structure, it is preferable that the surface of a pressing member is made into mirror surface finish. Filling and adhering the molten metal to the pressing member by contacting the surface with the molten metal and mirror-finishing the surface of the pressing member composed of the metal by polishing, lapping polishing, or electrolytic polishing, and reducing the surface roughness. Can be further suppressed. Therefore, after filling and hardening of the molten metal, it is effective to remove and chip the filled metal when the pressing member is pulled away from the object to be processed (poor filling of the molten metal) or to crack the object to be processed (for example, wafer crack). Can be suppressed.

  Furthermore, it is preferable that the surface of the pressing member made of the metal has a surface roughness of 0.3 μm or less.

  In this way, the metal surface of the pressing member can be made smooth so that the molten metal can be prevented from sticking accurately, and the hardened molten metal can be easily peeled off from the metal surface of the pressing member, and the above filling can be performed. Defects and cracks in the workpiece (for example, wafer cracks) can be effectively avoided.

  In the above configuration, it is also preferable that the surface of the pressing member made of the metal is subjected to a mold release treatment.

  For example, the pressing member is subjected to a release treatment such as DLC (Diamond Like Carbon) film treatment on the surface constituted by the metal of the pressing member, so that the pressing member is subjected to high pressure so that the molten metal and the object to be processed are applied. Even if it moves to this direction, the molten metal that has been cooled and hardened can be easily peeled off from the metal surface of the pressing member. Therefore, when the surface of the pressing member is pulled away from the hardened molten metal or the object to be processed, pulling out or chipping of the filled metal, cracking of the object to be processed (for example, wafer cracking) caused by the pressing member and the molten metal sticking to each other. ) And the like can be prevented.

  In the present invention, the size of the minute space (hole) formed on the workpiece is typically assumed to have a diameter of 0.1 μm to several tens of μm. As long as the molten metal enters, it does not matter whether it is a through-hole, regardless of its formation method and aspect ratio. Further, the shape of the hole is not limited, and may be any shape such as a straight shape, a curved shape, or a crank shape, and the presence or absence of branching is not questioned. If it is a non-through-hole, the depth can be made into arbitrary things of several hundred micrometers or less, for example according to the thickness of a to-be-processed object.

  According to the metal filling apparatus according to the present invention, it is possible to accurately fill the molten metal into the minute space formed on the object to be processed while avoiding poor filling and cracking of the object to be processed.

It is sectional drawing which showed schematic structure of the metal filling apparatus which concerns on one Embodiment of this invention. It is explanatory drawing which shows the operation | movement flow of the metal filling apparatus of the said embodiment. It is explanatory drawing which shows the operation | movement flow of the metal filling apparatus of the said embodiment. It is explanatory drawing which shows the operation | movement flow of the metal filling apparatus of the said embodiment. It is explanatory drawing which shows the operation | movement flow of the metal filling apparatus of the said embodiment. It is explanatory drawing which shows the operation | movement flow of the metal filling apparatus of the said embodiment. It is explanatory drawing which shows the operation | movement flow of the metal filling apparatus of the said embodiment. It is explanatory drawing which shows the operation | movement flow of the metal filling apparatus of the said embodiment. (A) is sectional drawing which shows the structure which provides a molten metal sealing part in a piston, (b) is sectional drawing which shows a mode when the piston of (a) is dropped toward a semiconductor wafer. is there. It is sectional drawing which shows the further structure which provides a molten metal sealing part in a piston, (b) is sectional drawing which shows a mode when the piston of (a) is dropped toward a semiconductor wafer. (A) is sectional drawing which shows the further structure of the molten metal sealing part provided in a piston, (b) is sectional drawing which shows a mode when the piston of (a) is dropped toward a semiconductor wafer. It is. (A) is sectional drawing which shows the further structure of the molten metal sealing part provided in a piston, (b) is sectional drawing which shows a mode when the piston of (a) is dropped toward a semiconductor wafer. It is. (A) is sectional drawing which shows the further structure of the molten metal sealing part provided in a piston, (b) is sectional drawing which shows a mode when the piston of (a) is dropped toward a semiconductor wafer. It is. (A) is sectional drawing which shows the micro space on the semiconductor wafer before metal filling, (b) is sectional drawing which shows the said micro space with metal filling favorable, (c) is a filling defect. It is sectional drawing which shows the said micro space produced.

  Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

[1. Configuration of metal filling equipment]

  As shown in FIG. 1, a metal filling apparatus 1 according to the present embodiment is a metal filling apparatus that fills molten metal into a minute space formed so as to open on the surface of a semiconductor wafer K (object to be processed). The holding base H for holding the semiconductor wafer K closes the lower end of the cylindrical housing C (cylindrical member) in an airtight manner, and is fitted in an airtight manner with the housing C, and the central axis of the housing C A piston P that can move forward and backward is provided, and a processing chamber 2 surrounded by a housing C, a piston P, and a holding table H is provided.

  The metal filling device 1 includes a decompression mechanism 3 that exhausts the gas in the processing chamber 2 to depressurize the processing chamber 2, a molten metal supply mechanism 4 that supplies the molten metal M into the processing chamber 2, A pressurized gas supply mechanism 7 for supplying an inert gas to the substrate, a molten metal recovery mechanism 8 for recovering the molten metal supplied into the processing chamber 2, an elevating mechanism 16, a pressing mechanism 5, a pressure reducing mechanism 3, and a molten metal supply And a control device 15 for controlling the operation of the mechanism 4, the pressurized gas supply mechanism 7 and the molten metal recovery mechanism 8.

  The holding table H is moved up and down by an elevating mechanism 16. The holding table H is raised toward the housing C, and the upper surface of the holding table H is brought into contact with the lower end surface of the housing C so as to be airtight. Process chamber 2 is formed. The lifting mechanism 16 is composed of a torque motor or the like, and its operation is controlled by the control device 15.

  The pressing mechanism 5 is a so-called hydraulic cylinder mechanism that provides a driving force for moving the piston P forward and backward, and can press the pressing portion 6 of the piston P against the semiconductor wafer K with a predetermined pressing force. Although not shown, the pressing mechanism 5 is connected to piping for supplying pressure oil to the upper chamber in the drawing and the lower chamber in the drawing, and the operation of each of the pipings is controlled by the control device 15. The piston P moves downward when pressure oil is supplied to the upper chamber, and moves upward when pressure oil is supplied to the lower chamber. Moving.

  A pressing portion 6 made of stainless steel 440C having heat resistance (or stainless steel 304) is provided on the side of the piston P facing the holding base H, and the pressing portion 6 of the piston P is made of semiconductor by a predetermined pressing force. The wafer K can be moved. Stainless steel is excellent as a material for the pressing portion 6 in that the surface state is stable even when used in a high temperature environment and has sufficient hardness.

  The piston P is inserted from the upper opening of the housing C and is advanced and retracted in the axial direction by the pressing mechanism 5. An O-ring 13 is interposed between the outer peripheral surface of the piston P and the inner peripheral surface of the housing C, and the gap between the two is sealed by the O-ring 13. Further, a bellows seal 17 is provided between the flange portion of the piston P and the upper end surface of the housing C, and the airtightness between the piston P and the housing C is further enhanced by the bellows seal 17. .

  Of the surface of the pressing portion 6, at least a region in contact with the molten metal M is electropolished and mirror-finished. As a result of the mirror surface processing, in the prototype metal filling device 1, the pressing portion 6 has a surface roughness of 10 μm average roughness (Rz) of 0.3 μm or less and a maximum height (Ry) of 0.5 μm or less. The average distance (Sm) is 10 μm or more. As described above, if the surface roughness (ten-point average roughness) of the pressing portion 6 is set to 0.3 μm or less and the metal surface of the pressing portion 6 is made smooth, the molten metal M adheres to the pressing portion 6 side. Therefore, even when the pressing portion 6 is pulled away from the semiconductor wafer K, the molten metal M that has been cooled and hardened is easily peeled off from the metal surface of the pressing portion 6, so that filling failure, cracking of the semiconductor wafer K, etc. Can be effectively avoided.

  In this application, the term “surface roughness” refers to the JIS standard 10-point average roughness.

  The surface of the pressing part 6 is subjected to a DLC film treatment (release process), and even if the pressing part 6 is pressed against the molten metal with a strong force, the hardened filling metal is easily peeled off from the pressing part 6. It has come to be.

  As the mold release process, in addition to the DLC process, a CrN coating process, a TiN coating process, a surf process, or the like can be suitably used. In the pressing part 6 of the prototype metal filling apparatus 1, the micro Vickers hardness (Hv) was larger than 1200 in the state where the above-described mirror surface processing or mold release processing was performed.

  Since the metal pressing portion 6 is relatively less deformed by heating and pressing, the coating process applied to the surface thereof is difficult to drop, and the effect of the coating process can be extended.

  The decompression mechanism 3 is provided in a vacuum pump 3a connected to the processing chamber 2 by a piping 11 provided through a side wall on the upper end side of the housing C, and a piping 11 between the vacuum pump 3a and the processing chamber 2. The control valve 3b is a mechanism for exhausting the air in the processing chamber 2 by the vacuum pump 3a to depressurize the processing chamber 2. The operation of the vacuum pump 3a and the opening and closing of the control valve 3b are controlled by the control device 15.

  Further, the molten metal supply mechanism 4 includes a molten metal supply unit 4 a connected to the processing chamber 2 by a pipe 9 penetrating the side wall on the lower end side of the housing C, a molten metal supply unit 4 a and the processing chamber 2. And a control valve 4b provided in the pipe 9 between them, and is a mechanism for supplying the molten metal M from the molten metal supply part 4a into the processing chamber 2 at a predetermined supply pressure. The control valve 4b is controlled to open and close. It is controlled by the device 15.

  In the molten metal supply part 4a, the molten metal M used for metal filling is heated at a temperature higher than the melting point, and is stocked in a liquid state. In this embodiment, the molten metal M used for metal filling is lead-free solder having a melting point of about 200 ° C. A metal having a relatively low melting point such as solder is excellent in that it is easy to handle. However, the type of molten metal M in the present invention is not limited to solder, and the purpose and function of filling a minute space. Depending on the case, any metal such as Au, Ag, Cu, Pt, Pd, Ir, Al, Ni, Sn, In, Bi, Zn, and alloys thereof can be adopted.

  The pressurized gas supply mechanism 7 includes a pressurized gas supply unit 7a connected to the pipes 11 and 9 by a pipe 10, and a control provided in the pipe 10 between the pipe 11 and the pressurized gas supply unit 7a. It consists of a valve 7b and a control valve 7c provided between the pipe 9 and the pressurized gas supply part 7a, and from the pressurized gas supply part 7a to the inside of the processing chamber 2 via the pipe 9, the pipe 10 and the pipe 11. This is a mechanism for supplying an inert gas to the tank. The operation of the pressurized gas supply unit 7a and the opening and closing of the two control valves 7b and 7c are controlled by the control device 15.

  The molten metal recovery mechanism 8 includes a molten metal recovery unit 8a connected to the processing chamber 2 by a pipe 12 penetrating the side wall on the lower end side of the housing C, and between the molten metal recovery unit 8a and the processing chamber 2. The control valve 8 b provided in the pipe 12 is a mechanism for recovering molten metal in the processing chamber 2, and the control valve 8 b is controlled by the control device 15 to open and close. In addition, as the molten metal collection | recovery part 8a, the structure which consists of a collection tank and the exhaust apparatus connected to this collection tank can be illustrated.

[2. (Metallic filling procedure)

  Next, a metal filling procedure in the metal filling apparatus 1 of this embodiment will be described with reference to FIGS.

  First, the control device 15 controls the operation of the elevating mechanism 16 to lower the holding table H, so that the upper surface of the holding table H is separated from the lower end surface of the housing C, and then a minute space is formed on the surface. The semiconductor wafer K is placed on the holding table H with its surface facing up. Next, the operation of the lifting mechanism 16 is controlled by the control device 15, the holding table H is raised toward the housing C, and the upper surface of the holding table H is brought into contact with the lower end surface of the housing C to form the processing chamber 2. . At this time, the lower end surface of the housing C is brought into contact with the surface of the semiconductor wafer K so that the semiconductor wafer K is pressed onto the holding table H.

  After that, as shown in FIG. 2, the vacuum pump 3 a is operated under the control of the control device 15, the control valve 3 b of the pipe 11 is opened, the gas in the processing chamber 2 is exhausted, and the inside of the processing chamber 2 is exhausted. And the pressure in the minute space is reduced to a substantially vacuum state.

  Next, as shown in FIG. 3, while the pressure reduction by the vacuum pump 3a is continued, the control valve 4b of the pipe 9 is opened by the control device 15 while the inside of the processing chamber 2 is maintained in a substantially vacuum state, and molten metal is supplied. The liquid molten metal M heated to the melting point or higher from the portion 4a is supplied into the processing chamber 2 until it reaches an amount that covers the entire surface of the semiconductor wafer K without being repelled on the surface of the semiconductor wafer K. . In the metal filling device 1, the pipe 11 is provided so as to penetrate the upper end side of the housing C, that is, the pipe 11 is provided sufficiently above the liquid level of the molten metal to be supplied. Although it is possible to supply the molten metal M in a state where the pressure reduction due to the pressure is continued, the molten metal M is supplied at an appropriate timing so that the molten metal M is not sucked into the vacuum pump 3a. It is preferable to stop the supply. Further, as described above, by pressing the semiconductor wafer K onto the holding table H, for example, solder (specific gravity: about 9.0) is applied to the semiconductor wafer made of silicon (specific gravity: about 2.5). Even if the semiconductor wafer is supplied, the semiconductor wafer is prevented from floating above the holding table.

  In addition, since it is not preferable that the molten metal M is cooled and solidified before entering the press process described later, at this stage, the inside of the processing chamber 2 is kept at a temperature equal to or higher than the melting point of the molten metal M, Must remain liquid.

  When a sufficient amount of molten metal M is supplied to the inside of the processing chamber 2, as shown in FIG. 4, the control valve 4 b of the pipe 9 is closed by the control device 15, and then pressed under the control of the control device 15. By actuating the mechanism 5, the piston P in the processing chamber 2 is slowly advanced toward the semiconductor wafer K so that the surface of the pressing portion 6 is in the molten metal M supplied into the processing chamber 2. Sink. In this way, it is possible to avoid the formation of an air layer between the pressing portion 6 and the molten metal M by sinking the surface of the pressing portion 6 in the molten metal M while the inside of the processing chamber 2 is in a substantially vacuum state. it can.

  Next, as shown in FIG. 5, the control valve 3b of the pipe 11 is closed by the control device 15 while the surface of the pressing portion 6 is kept submerged in the molten metal M, and the operation of the vacuum pump 3a is stopped. While the pressure reduction is stopped, under the control of the control device 15, the control valve 7b of the pipe 10 is opened and the pressurized gas supply unit 7a is operated to supply nitrogen gas for pressurization from the pressurized gas supply unit 7a. The molten metal M is supplied into the processing chamber 2 and pressed against the surface of the semiconductor wafer K by gas pressurization. By this gas pressurization, even if the wettability between the molten metal M and the semiconductor wafer K is poor, it is possible to fill the metal in the minute space of the semiconductor wafer K by so-called differential pressure filling.

  Next, as shown in FIG. 6, the pressing mechanism 5 is operated by the control device 15 to further move the piston P toward the semiconductor wafer K, and the pressing portion 6 is moved toward the surface of the semiconductor wafer K. As a result, surplus molten metal between the pressing portion 6 and the semiconductor wafer K is pushed out from the semiconductor wafer K into the gap between the inner peripheral surface of the housing C and the outer peripheral surface of the piston P. The amount of residue formed on the surface of the wafer K is reduced.

  In the metal filling device 1, as the pressing portion 6 is moved into the liquid of the molten metal M, the molten metal M is moved to the gap between the inner peripheral surface of the housing C and the outer peripheral surface of the piston P. Therefore, the liquid level of the molten metal M rises. As a result, the semiconductor wafer K is immersed in the molten metal M at a deep position from the liquid surface of the molten metal M, so that the pressing portion 6 and the semiconductor wafer K come into contact with each other, and the molten metal M and the semiconductor wafer K and Even if the force of repelling the molten metal M on the surface of the semiconductor wafer K becomes strong due to the poor wettability with the pressing portion 6, the film of the molten metal M is hardly cut off on the surface of the semiconductor wafer K. On the other hand, for example, in the configuration as described in Patent Document 1, even if a pressing pressure is applied, the molten metal is pushed away from the semiconductor wafer and the film is cut, so that accurate metal filling is realized. I can't.

  Also in the pressing step, it is preferable to continue the gas pressurization by the pressurized gas supply unit 7a. Thereby, the filling force is maintained and the above-mentioned film breakage can be effectively prevented.

  Next, as shown in FIG. 7, in a state where the pressing portion 6 is pressed against the surface of the semiconductor wafer K, the control valve 7c of the pipe 10 is opened by the control device 15 and the control valve 8b of the pipe 12 is opened. The excess molten metal M that cannot be filled in the minute space of the wafer K is recovered to the molten metal recovery unit 8a. At this time, if the excessive molten metal M is not recovered, after the cooling described later, the excessive molten metal M hardens in the gap between the housing C and the pressing portion 6 to prevent the piston P from moving up or down, or the semiconductor wafer K And the wall surface of the processing chamber 2 are fixed. However, if a gas enters between the pressing unit 6 and the semiconductor wafer K, a filling defect occurs. Therefore, all the surplus metal is not discharged, and the gap between the side wall of the pressing unit 6 and the inner wall of the housing C is melted. The state in which the metal M is left is left. The amount of the molten metal M left in the gap is preferably about several mm depending on the height, although it depends on the wettability between the semiconductor wafer K and the pressing portion 6 and the molten metal M and the size of the gap. .

  Then, after recovering the excess molten metal M, under the control of the control device 15, the two control valves 7b and 7c of the pipe 10 are closed to stop the supply of the pressurizing gas, and the control valve 8b of the pipe 12 is turned off. close up. Thereafter, the heating or heat retention inside the processing chamber 2 is stopped, the molten metal M is cooled until the temperature becomes the melting point or lower, and the process waits until the molten metal filled in the minute space of the semiconductor wafer K is cooled and hardened.

  Next, as shown in FIG. 8, under the control of the control device 15, the pressing mechanism 5 is operated to slowly raise the piston P, and the lifting mechanism 16 is further operated to lower the holding base H. Then, the processing chamber 2 is released. Then, the semiconductor wafer K that has been subjected to the metal filling process is taken out of the holding table H, and is replaced with a new semiconductor wafer K that is to be subjected to the metal filling process. When filling a plurality of semiconductor wafers K with metal, the procedure shown in FIGS. 2 to 8 may be repeated as appropriate.

  In the above description, the holding table H is configured to close one end of the housing C in an airtight manner. However, the semiconductor wafer K held on the holding table H does not seal the one end of the housing C, but the holding table H itself. It is good also as an apparatus design which closes in a shape.

[3. Shape of molten metal sealing part]

  Next, as a preferred embodiment, in the above-described configuration, a configuration in which a molten metal sealing portion that confines the molten metal M supplied by the molten metal supply mechanism 4 between the pressing portion 6 and the semiconductor wafer K will be described. .

  As a first aspect of providing the molten metal sealing portion, as shown in FIG. 9A, the lower surface of the pressing portion 6 has a ring shape made of an elastic body along the outer periphery of the circular semiconductor wafer K. There exists an aspect which provides the sealing part 20 (molten metal sealing part). In the figure, the configuration of the thick portion with hatching is omitted (the same applies to FIGS. 10 to 13).

  According to this configuration, when the pressing unit 6 is brought close to the semiconductor wafer K (see FIG. 6), the amount of the excess molten metal M that escapes the excess molten metal M to the outside and becomes a residue on the semiconductor wafer K. Can be reduced sufficiently. That is, until the sealing portion 20 comes into contact with the semiconductor wafer K, the molten metal M in the inner region of the sealing portion 20 escapes to the outside of the region, whereas the sealing portion 20 contacts the semiconductor wafer K. When coming closer and in surface contact (contact) with the surface of the semiconductor wafer K, the molten metal M is confined in the inner region of the sealing portion 20 (see FIG. 9B).

  By providing the sealing part 20, especially the sealing part 20 made of an elastic body, good sealing performance can be obtained. And since the sealing part 20 deform | transforms by the movement of the pressing part 6 and a sealing area | region is narrowed, high pressure can be efficiently applied to the molten metal M in the said sealing area | region using the thrust of the pressing mechanism 5. FIG. The molten metal M can be filled in the minute space on the surface of the semiconductor wafer K without a gap.

  By performing gas pressurization and pressurization by the pressing unit 6 including the sealing unit 20 in two stages, metal filling can be realized even when the wettability between the molten metal M and the semiconductor wafer K is poor. is there. Specifically, first, gas is pressurized, and the molten metal M on the entire processing surface of the semiconductor wafer K inside the sealing portion 20 is high due to the movement of the pressing portion 6 including the sealing portion 20. The filling process can be performed by applying pressure. By adopting such a method, effective metal filling can be realized by two-stage pressurization of gas pressurization and pressure addition pressure without making the pressure vessel performance of the processing chamber extremely high.

  Furthermore, if the pressing part 6 provided with the sealing part 20 is used, even if the excess molten metal M ′ outside the sealing range is discharged using a gas blow, liquid rinse or the like in the subsequent surplus metal discharging step, the sealing range. Since the metal filling property of the minute space inside is not affected, a more effective surplus metal discharging means can be used. That is, in this embodiment, since the sealing portion 20 exists, unlike the previous embodiment, even if all of the excess molten metal M ′ is discharged, gas enters between the pressing portion 6 and the semiconductor wafer K. Since no filling failure occurs, it becomes possible to keep the region outside the sealing range clean.

  Moreover, as a 2nd aspect which provides a molten metal sealing part, as shown to Fig.10 (a), in the lower surface of the pressing part 6, in the position facing the holding stand H outside the semiconductor wafer K, it is circular. There exists an aspect which provides the sealing part 21 (molten metal sealing part) which consists of a semiconductor wafer K and a concentric elastic body.

  According to this configuration, since the sealing portion 21 is provided outside the semiconductor wafer K, the sealing portion 21 does not contact the semiconductor wafer K, and the entire surface of the semiconductor wafer K is filled with the molten metal M. (See FIG. 10B).

  The material forming the molten metal sealing portion is not particularly limited as long as it has a certain degree of elasticity and heat resistance and is suitable for sealing, but the molten metal M before sealing is likely to escape to the outside. By adopting the material and the structure, the amount of the molten metal M to be sealed can be minimized, and the residue on the semiconductor wafer K can be thinned.

  Next, as a third embodiment in which a molten metal sealing portion is provided, as shown in FIG. 11A, an elastic body layer 22 (molten metal sealing) is provided on the side of the pressing portion 6 opposite to the surface in contact with the molten metal M. Part) is laminated. In this case, when the piston P is moved toward the semiconductor wafer K by the pressing mechanism and the pressing portion 6 is moved closer to the molten metal M and the semiconductor wafer K, as shown in FIG. The body layer 22 spreads in a plane perpendicular to the pressurizing direction, and the spread elastic body layer 22 comes into contact with the housing C, so that the molten metal M is confined in the space sealed by the elastic body layer 22. It is done. According to such a configuration, sealing is performed so as to maintain the pressure of the molten metal M that has been gas-pressurized in advance.

  According to the above configuration, even when the parallelism between the surface of the semiconductor wafer K and the surface of the pressing portion 6 is poor, the surface of the semiconductor wafer K and the surface of the pressing portion 6 can be efficiently brought into close contact with each other by deformation of the elastic layer 22. it can. Further, by making the metal part of the pressing part 6 easy to deform, even when the flatness of the surface of the semiconductor wafer K is poor, the surface of the semiconductor wafer K and the surface of the pressing part 6 due to the deformation of the elastic body layer 22 and the metal thin plate. Can be efficiently adhered, cooled by holding pressure, and the molten metal M can be cured, so that the residue on the semiconductor wafer K can be made thinner by these adhesion effects.

  Next, as a fourth aspect in which a molten metal sealing portion is provided, as shown in FIG. 12A, an elastic body layer 23 (molten metal sealing) is provided on the opposite side of the pressing portion 6 to the surface in contact with the semiconductor wafer K. In addition, a ring-shaped sealing portion 24 (molten metal sealing portion) made of an elastic body is provided on the lower surface of the pressing portion 6 along the outer periphery of the circular semiconductor wafer K. There are aspects. In this case, when the piston P is moved toward the semiconductor wafer K by the pressing mechanism 5, the pressing portion 6 is brought close to the molten metal M and the semiconductor wafer K, and the sealing portion 24 is brought into contact with the semiconductor wafer K. As shown in FIG. 4B, the molten metal M is sealed in the region surrounded by the sealing portion 24. According to this aspect, compared with the third aspect, the effective sealing range is narrowed to the region of the semiconductor wafer K, whereby the molten metal M ′ outside the region surrounded by the sealing portion 24 is recovered by the molten metal. By appropriately collecting by the mechanism, the amount of residual metal remaining in the extra gap can be reduced.

  Next, as a fifth embodiment in which the molten metal sealing portion is provided, as shown in FIG. 13A, the piston P is opposite to the surface from the outer region of the surface of the pressing portion 6 in contact with the molten metal M. There is a form in which the elastic body layer 25 (molten metal sealing portion) is laminated on the side. The elastic body layer 25 around the pressing portion 6 has a structure protruding slightly downward from the pressing portion 6. In this case, when the piston P is moved toward the semiconductor wafer K by the pressing mechanism, the pressing portion 6 is brought close to the molten metal M and the semiconductor wafer K, and the elastic body layer 25 is brought into contact with the semiconductor wafer K. The molten metal M is sealed in the contact area of the elastic body layer 25 as shown in FIG. Unlike the embodiment shown in FIG. 11, the molten metal M ′ in the gap with the housing C is not sealed.

  As described above, by providing various molten metal sealing portions, the molten metal M can be confined between the pressing portion 6 and the semiconductor wafer K, and the sealing performance can be improved in a wide region on the semiconductor wafer K. Therefore, the molten metal M can be pushed into the minute space of the semiconductor wafer K by applying an appropriate high pressure to the molten metal M. Further, in the case where the residue generated on the semiconductor wafer K can be reduced and the molten metal M is confined only on the semiconductor wafer K, the molten metal M ′ outside the region surrounded by the molten metal sealing portion is used. It is possible to reduce excess molten metal remaining in the processing chamber by collecting the molten metal by the molten metal recovery mechanism.

  As a result, it is possible to push the molten metal into the minute space without any gap, avoid the generation of voids during filling, and realize highly accurate metal filling.

  Finally, a state in which the metal filling is satisfactorily performed according to the present invention is illustrated. FIG. 14A is a cross-sectional view showing the minute space V on the semiconductor wafer K before filling with the molten metal M, and the lower part in the drawing is the semiconductor wafer K. FIG. In FIG. 2A, innumerable minute spaces V are regularly arranged on the surface of the semiconductor wafer K. FIG. 14B is a cross-sectional view showing a state in which the minute space V on the semiconductor wafer K is satisfactorily filled with the molten metal M and the residue on the semiconductor wafer K is removed according to the present invention. In FIG. 5B, it can be seen that the minute space V is filled with the molten metal M without a gap.

  On the other hand, FIG.14 (c) is sectional drawing which shows the microspaces V1-V4 which produced the filling defect of the molten metal M as a comparative example. In FIG. 5C, in the minute spaces V1 and V2, although the molten metal M is filled on the bottom side, the amount is not sufficient, so that the minute space cannot be completely filled. Moreover, in the minute spaces V3 and V4, it can be seen that the molten metal M does not reach the bottom side and is in a poor filling state.

  As mentioned above, although embodiment of this invention was described, the specific aspect which this invention can take is not limited to this at all.

  For example, in the above example, the configuration in which the pressing unit 6 is brought closer to the semiconductor wafer K is adopted, but the present invention is not limited to this, and the configuration in which the semiconductor wafer K (holding base H) is brought closer to the pressing unit 6. May be adopted.

  Further, in the above example, after supplying the molten metal M, the piston P is moved toward the semiconductor wafer K, the pressing portion 6 is brought close to the liquid surface of the molten metal M, and the pressing portion 6 is submerged in the molten metal M. However, instead of bringing the pressing portion 6 close to the liquid surface, the molten metal M is supplied until the surface of the pressing portion 6 is immersed in the molten metal M. The pressing unit 6 may be in a state of being submerged in the molten metal M.

  Further, the pressing direction by the pressing unit 6 is not limited to the form of pressing from the vertically upward direction to the downward direction, and may be pressed from the vertically downward direction to the upward direction or may be pressed in the horizontal horizontal direction depending on the configuration of the apparatus. Further, the orientation of the metal filling device is not limited to the orientation shown in FIG. 1, and may be the orientation in which the orientation in FIG. 1 is turned over, or the orientation in which the top and bottom are inverted.

  Further, the movement of the pressing unit 6 does not necessarily depend on the control operation of the pressing mechanism 5 but may be brought close to the semiconductor wafer K by, for example, human power.

  As described above, the present invention can be suitably used for a metal filling apparatus that fills molten metal into a minute space on the surface of a workpiece.

DESCRIPTION OF SYMBOLS 1 Metal filling apparatus 2 Processing chamber 3 Pressure reduction mechanism 4 Molten metal supply mechanism 5 Pushing mechanism 6 Pushing member C Housing H Holding stand K Semiconductor wafer P Piston

Claims (7)

The object to be processed front surface micro space formed so as to open to the, a metal filling apparatus for filling a molten metal supplied onto該被treated,
A holding unit for holding the object to be processed;
A cylindrical member having an internal space and having one end facing the holding portion;
A pressing member that is fitted in the inner space of the cylindrical member so as to freely advance and retract , and presses the molten metal against the object to be processed ;
A depressurization mechanism for depressurizing a processing chamber formed in an airtight manner by the object to be processed or the holding unit held by the holding unit, and the cylindrical member and the pressing member;
A molten metal supply mechanism for supplying molten metal into the processing chamber;
Under pressure the molten metal supplied into the processing chamber provided with a pressurizing mechanism to push the molten metal into the minute space,
The pressing member is a metal filling device, wherein at least a side facing the object to be processed is made of metal.   The metal filling apparatus according to claim 1, further comprising a pressing mechanism that moves the pressing member forward and backward with respect to an object to be processed held by the holding unit.   The metal filling device according to claim 1, further comprising a moving mechanism that moves at least one of the holding portion and the cylindrical member in a direction in which the holding portion and the cylindrical member approach and separate from each other.   The molten metal sealing portion for confining the molten metal supplied by the molten metal supply mechanism between the pressing member and the surface of the object to be processed is provided in the pressing member. The metal filling device according to any one of the above.   5. The metal filling apparatus according to claim 1, wherein the pressurizing mechanism is a pressurized gas supply mechanism that supplies a pressurized gas into the processing chamber.   6. The metal filling device according to claim 1, wherein the surface of the pressing member made of the metal has a surface roughness of 0.3 μm or less.   The metal filling device according to any one of claims 1 to 6, wherein a surface of the pressing member made of the metal is subjected to a mold release process.

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