JP2007208296A - Member with filling metallic portion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a member with a filling metallic portion capable of securely filling molten metal in the vicinity of openings, especially openings which open on the work outer surface of fine pores formed on the work. <P>SOLUTION: In a member with a filling metallic portion according in the fine pore 11 formed in a work 10, the member has a filling metallic portion 22 formed by filling molten metal therein, and a metal layer 15 is formed in a region including an internal surface located at the edge opening at least to an outer surface of the work of the fine pore in the internal surface thereof. The filling metallic portion fills in the fine pore including the edge, where the metallic layer of the fine pore is formed, and provided so that electric conduction is secured. It is configured in such a way that one end forms a weld overlay and the other end makes flatness and a through electrode filling in the fine pore and bump composed of the weld overlay are integrally formed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a member with a filling metal part that fills a fine hole formed in a member such as a through hole and a non-through hole formed in a circuit board with metal.

  For example, when a through electrode (via hole electrode) is formed on a substrate (silicon substrate or the like) in the manufacturing process of an IC chip or the like, a through hole for the through electrode is formed in the substrate, and the substrate is melted by melting a metal for a conductor. It is common to employ a plating method that inserts and immerses in a metal (plating solution) and fills the through hole with molten metal.

  However, when filling the through hole with metal by plating, the plating layer grows intensively near the through hole entrance of the substrate for some reason, making it difficult for the plating solution to enter the deep side of the through hole There is. In this case, there is a problem that it is difficult to fill the metal without voids, such as a void inside the through hole.

  In particular, when the through hole is a fine hole having a high aspect ratio (hole depth / opening diameter), it is difficult to allow the molten metal to penetrate deep into the through hole. Concentrated growth tends to occur, and the above-mentioned problem becomes remarkable. For example, in high-density three-dimensional mounting in which silicon IC chips or the like are stacked, a through electrode (through wiring) may be formed on the substrate to connect the wiring patterns on the front and back of a single substrate. Since the through hole for use is a fine hole with a high aspect ratio, it is difficult to reliably form a through electrode without a gap when filling the through hole with metal by the above-described plating method to form a through electrode. is there.

  In view of the above-mentioned problems, the present invention provides a member with a filling metal part that can reliably fill molten metal in the vicinity of an opening of a fine hole formed in a work, particularly in the outer surface of the work. It is aimed.

The present invention is a method of filling a fine hole formed in a workpiece with a metal, and after forming a metal layer on the inner surface of the end of the fine hole that opens to the outer surface of the workpiece, the workpiece is immersed in molten metal. A metal filling method characterized by crushing and filling the fine holes with molten metal, and then taking out the workpiece from the molten metal and cooling while closing one end along the axial direction of the fine holes. Use.
In this metal filling method, the fine hole is a through-hole penetrating the work, and the metal layer is formed on the inner surface of at least one end of the through-holes in the axial direction, and is immersed in molten metal. When taking out the work in which the through-hole is filled with molten metal from the molten metal, the opening at the other end in the axial direction of the through-hole is closed with a sealing material as one end in the axial direction of the fine hole. A configuration can also be employed. Furthermore, a metal layer is formed on the outer surface of the work extending around the end of the fine hole formed on the outer surface of the fine hole, as well as on the inner surface of the fine hole. After immersing in the molten metal in the molten metal tank and filling the fine hole with the molten metal, before cooling the work, the end of the fine hole of the work taken out from the molten metal is opened to the outer surface of the work. The molten metal filled in the fine holes is built up on the presence portion of the metal layer formed around the inner surface and the end opened to the outer surface of the work, and then the fine holes are cooled by cooling the work. It is also possible to integrally form the filled metal portion formed by solidification of the molten metal and the external metal portion formed by solidification of the build-up portion of the molten metal.
Further, in the metal filling method described above, before the work is immersed in the molten metal, the metal layer around the opening of the fine hole on the outer surface of the work is patterned corresponding to the shape of the external metal part to be formed. It is also possible.
The member with a filling metal part according to claim 1 of the present invention has a filling metal part formed by filling molten metal into the fine hole in the fine hole formed in the workpiece, A metal layer is formed in a range including at least an inner surface located at an end of the fine hole that opens to the work outer surface of the fine hole, and the filled metal part is an end where the metal layer of the fine hole is formed. The inside of the fine hole including the portion is filled so as to ensure electrical conduction, and one end is built up and the other end is flat, and fills the inside of the fine hole. The through electrode and the bump made of the build-up are integrally formed and continuous.
The member with a filling metal part according to claim 2 of the present invention is the member according to claim 1, wherein the workpiece is a semiconductor substrate, and an insulating layer is provided on an inner surface of the fine hole with which the through electrode is in contact. Features.
The member with a filling metal part according to claim 3 of the present invention is the member according to claim 1, wherein the workpiece is a semiconductor substrate, the inner surface of a fine hole with which the through electrode is in contact, and one surface with which the build-up part is in contact Is characterized in that an insulating layer is provided.

The workpiece according to the present invention is for filling a metal that is a through hole (micro hole) or a non-through hole (a micro hole in which only one end along the axial direction is open on the work outer surface and the other end is not open). A member having a fine hole, for example, a substrate (circuit board) on which a via hole or a so-called inner via hole is formed. Various materials such as a semiconductor material such as silicon and gallium arsenide (GaAs) and an insulating material such as glass can be employed as the material of the workpiece.
As a technique for forming fine holes (either through holes or non-through holes) in the workpiece according to the present invention, Deep-Reactive (DRIE) represented by ICP-RIE (Inductively Coupled Plasma-Ractive Ion Etching) method. Examples thereof include a wet etching method using an etching solution, a machining method using a micro drill, and a photoexcited electrolytic polishing method. The diameter of the microhole, the workpiece size, the depth of the microhole, etc. are appropriately set according to the application etc. Further, the cross-sectional shape of the microhole (the cross-sectional shape perpendicular to the axial direction) is also round, elliptical, triangular, Any shape such as a rectangle (including a rectangle) may be used.

In the metal filling method according to the present invention, the work is crushed in the molten metal heated and melted, and the molten metal is poured into and filled in the fine holes, and then taken out from the molten metal while closing one end in the axial direction of the fine holes. Then, a technique is adopted in which the molten metal in the fine holes is solidified by cooling the taken-out work. When the fine hole is a through hole, a through wiring or the like can be formed by solidification of the molten metal filled in the fine hole of the work. When the fine hole is a non-through hole, the work piece as a filled metal part is formed by the solidified molten metal. Internal electrodes, internal wiring, etc. can be formed.
When taking out the workpiece from the molten metal, “leaving one end in the axial direction of the fine hole” means that if the fine hole is a through hole, it is along the axial direction of the through hole. This can be realized by closing the opening at one end with a sealing material. Further, when the fine hole is a non-through hole, the non-through hole itself has a configuration in which one end along the axial direction is opened and the other end is closed, so that it is not necessary to use a sealing material. Needless to say.

In the metal filling method according to the present invention, the molten metal that has been heated and melted is filled into the fine holes. Therefore, incomplete filling caused by intensive growth of the plating layer at the fine hole entrance in the case of the plating method (the voids described above). Formation etc.) can be avoided. In the present invention, “molten metal” is a metal melted by heating.
In the present invention, the immersion of the workpiece into the molten metal is to immerse the workpiece in the molten metal, in other words, the insertion of the workpiece into the molten metal. However, the soaking referred to here is not limited to the immersion of the work into the molten metal stored in a tank (hereinafter also referred to as a molten metal tank), but a container containing the work (including the aforementioned molten metal tank). Also includes injection of molten metal into the inside. Here, the “filling” of the fine holes is not limited to filling the whole inside of the fine holes without any gaps, and for example, leaving a void in a part in the axial direction of the fine holes (to non-through holes such as inner via holes). In the case of metal filling of the above, a configuration in which some space exists in the filling metal is also included in the “filling”. In the present invention, particularly, the metal filling in the vicinity of the opening of the fine hole is made firm, so that the electrical and mechanical characteristics of the filled metal portion can be sufficiently ensured. In addition, the “removal” of the workpiece from the molten metal means that the workpiece is lifted upward from the molten metal stored in the tank, taken out in the horizontal direction, or is immersed in the molten metal in the tank. It also includes exposing exposed workpieces by discharging molten metal from the tank.

  By the way, the present inventors verified the filling state of the molten metal in the fine holes after taking them out of the molten metal for a workpiece such as a substrate formed of silicon or glass, and as a result, simply melted into the fine holes. If the work is filled with metal and is pulled up from the molten metal (corresponding to “removal”) with the closed side of both ends in the axial direction of the fine hole as the lower end (corresponding to “removal”), The molten metal tends to flow out from the opening of the fine holes that open on the surface of the metal, and the molten metal flows out during the pulling process, resulting in many cases where the molten metal becomes insufficiently filled during cooling and solidification. I found it. When the molten metal flows out, the amount of molten metal contained in the fine hole is reduced. Therefore, for example, as shown in FIG. 15, the upper surface of the molten metal 2 in the fine hole 1 (FIG. 15 shows a through hole). However, it is slightly lower than the upper surface 4 of the workpiece 3 (FIG. 15 is a substrate), and a step D may be formed. Further, when a step is formed as shown in FIG. 15, for example, even if an attempt is made to form and bond a bump on the through wiring obtained by solidifying the molten metal in another process, the bonding is made between the bump and the through wiring. Defects are likely to occur, and it is easy to cause defects such as incomplete electrical connection.

The phenomenon that the molten metal flows out of the fine holes when the workpiece is lifted from the molten metal is caused by the fact that silicon or glass forming the workpiece cannot secure sufficient wettability with the molten metal. Since it is difficult to fit between the inner surface of the hole and the molten metal, the outflow of the molten metal from the fine holes easily occurs.
In the present invention, in the fine holes, the metal layer formed on the inner surface of the end on the upper side when the workpiece is taken out from the molten metal (taken out by lifting or the like), the wettability with the molten metal filled in the fine holes is improved. It was ensured. Thereby, when taking out the workpiece from the molten metal, the molten metal does not easily flow out from the opening of the fine hole, and inconveniences such as formation of a step near the opening of the fine hole can be prevented. More preferably, the metal layer is formed as wide as possible on the inner surface near the opening of the micropore. When the fine hole is a through-hole, if a metal layer is formed on the inner surface of both ends of the through-hole, the metal layer is not necessarily formed on the entire inner surface over the entire length along the axial direction of the through-hole. Molten metal can be blended in effectively, and is effective in preventing the formation of voids in the through holes.

When a metal layer is formed on the inner surface of the end of the fine hole that opens to the outer surface of the work and on the outer surface of the work that extends around the end of the fine hole, the molten metal wets the metal layer around the opening. Depending on the property, it is possible to more reliably prevent the molten metal from flowing out of the fine holes when the substrate is taken out from the molten metal. In addition, when the workpiece is taken out from the molten metal, the molten metal layer is formed along the metal layer (the metal layer around the opening) to cool the molten metal on the metal layer. By solidification, external metal parts such as grounds and bumps of wiring on the substrate can be formed. The external metal parts such as the ground and bumps formed here are those obtained by cooling and solidifying the molten metal built up on the existing part of the metal layer formed around the opening of the fine hole on the outer surface of the work. , Formed integrally with the filled metal portion solidified in the micropores. Since the external metal part such as the ground and the bump formed in this way is continuous with the filled metal part by the same type of metal as the filled metal part, compared with the case where it is formed separately from the filled metal part, There is an advantage that problems such as poor bonding do not occur.
Also, a joint part (joint part between the external metal part and the filling metal part) due to the difference in thermal expansion coefficient or the diffusion of the material that occurs when the external metal part and the filling metal part are different materials There is no problem of embrittlement.

  For example, when a bump as an external metal part is formed on a substrate as a workpiece, the size, shape, etc. can be adjusted depending on the formation range of the metal layer around the opening of the fine hole on one surface of the substrate. . When the substrate is taken out from the molten metal, the molten metal remaining on the opening of the micropores on one side of the substrate and the metal layer formed around the opening is removed by the surface tension, etc. Since it can be in a heaped state, a solid bump is obtained by solidifying it. Therefore, the height, size, etc. of the bumps can be adjusted by adjusting the formation range of the metal layer around the opening of the fine hole on one surface of the substrate by patterning or the like.

In the member with a filling metal portion according to the present invention, the end portion where the metal layer of the fine hole is formed is filled by the wettability of the metal layer formed on the inner surface of the end portion opened to the outer surface of the fine hole workpiece. Since the excellent adhesion between the filled metal part and the metal layer is ensured, the fixed state of the filled metal part in the vicinity of the opening of the fine hole can be stably maintained over a long period of time, and even with long-term use, Long-term stability can be obtained because peeling of the filled metal part from the inner surface of the fine hole and floating of the filled metal part in the fine hole can be reliably prevented.
Further, the outer surface of the workpiece, which is formed integrally with the filled metal portion and is formed so as to protrude from the outer surface of the workpiece, extends around the end portion where the metal layer of the fine hole is formed. In the structure formed so as to cover the metal layer formed on the metal, the filling metal part in the microhole and the external metal part can be integrally formed. There is no problem such as brittleness of the joint due to diffusion of the metal.

  As described above, according to the present invention, the wettability with the molten metal filled in the micropores is ensured by the metal layer formed on the inner surface of the end portion that opens to the outer surface of the workpiece among the both ends of the micropores. I did it. Accordingly, when the substrate is taken out from the molten metal, the molten metal does not easily flow out from the opening of the microhole, and inconveniences such as formation of a step near the opening of the microhole can be prevented. If there is no level difference, it is possible to reliably bond the bumps and the like formed in a separate process to the filling metal portion such as the through wiring in which the molten metal is solidified, and to prevent the bonding failure. In addition, if a metal layer is formed on the inner surface of the end of the fine hole that opens to the outer surface of the workpiece, voids are generated inside the fine hole (especially near the end that is closed when immersed in molten metal) (Smooth voids) can be effectively prevented, the entire fine holes can be filled with molten metal reliably, and solid through-wirings free from steps and voids can be formed.

By forming a metal layer around the opening of the microhole on the outer surface of the work as well as the inner surface near the opening of the microhole, the wettability of the molten metal to the metal layer around this opening causes It is possible to more reliably prevent the molten metal from flowing out of the fine holes when the workpiece is taken out of the workpiece. In addition, when the substrate is taken out from the molten metal, the molten metal layer is formed along the metal layer (the metal layer around the opening) to cool the molten metal on the metal layer. The ground and bumps of the wiring on the substrate can be formed by solidification.
The outer metal part is continuously cooled from the fine holes, and is obtained by cooling and solidifying the molten metal built up on the opening parts of the fine holes on the outer surface of the work and the metal layer formed around the openings. If there is, since it is integrally formed with the filled metal portion formed by the molten metal solidified in the micropores, there is an advantage that problems such as poor bonding with the filled metal portion do not occur. In addition, the brittleness of the joint (joint between the external metal part and the filled metal part) due to the difference in thermal expansion coefficient or the diffusion of the material that occurs when the external metal part and the filled metal part are made of different materials Long-term reliability is improved without any problem.
When forming the metal layer around the opening of the micro hole on the outer surface of the workpiece, the metal layer is patterned in accordance with the shape (bump shape, etc.) of the target external metal portion to be formed. Etc. can be formed easily. In this case, there is an advantage that the height, size, etc. of the bumps can be easily adjusted by adjusting the formation range of the metal layer around the opening of the fine hole on the outer surface of the work by patterning.

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

(First embodiment)
First, the metal filling method and member with a filling metal part of 1st Embodiment which concern on this invention are demonstrated.
The metal filling method of this embodiment is a through-hole for connecting wiring patterns on both front and back surfaces (both front and back surfaces correspond to work outer surfaces) of a substrate as a workpiece (hereinafter, the workpiece may be referred to as “substrate”). This is a method of forming wirings and bumps (hereinafter, the metal filling method of this embodiment may be referred to as a “penetrating wiring forming method”).

As shown in FIG. 1, the substrate used in this metal filling method is one in which a plurality of through holes 11 for through wiring (hereinafter, the micro holes may be referred to as through holes) are formed as fine holes. . Here, a silicon substrate is used as the substrate 10, but the substrate is not limited to this. For example, a semiconductor material such as gallium arsenide (GaAs), an insulating material such as glass or ceramic, or a synthetic resin can be used. It is.
Furthermore, for example, a composite substrate in which an organic material such as an epoxy resin is laminated and integrated with a glass or silicon substrate can also be used. In addition, as a substrate, an electric circuit is directly formed on one or both main surfaces (front and back surfaces), a circuit forming platform is formed on one or both main surfaces, a combination of these, etc. Various configurations can be adopted. The thickness of the substrate 10 is about several hundred μm.
The through wiring formed on the substrate 10 corresponds to the filled metal portion according to the present invention, and the bump corresponds to the external metal portion according to the present invention. In this embodiment, the “substrate” can be read as a work, the through hole is a fine hole, the through wiring is a filled metal portion, and the bump is an external metal portion. In addition, the description of “a method for forming a through wiring” can be read as a metal filling method.

  This through-wiring forming method includes a step (metallization) of forming a metal layer on the inner surface of the opening of the through-hole and the periphery of the opening on both the front and back surfaces of the substrate (metallization step), and a substrate that has completed this metallization step, A molten metal filling process in which the molten metal (heated and melted metal) stored in the molten metal tank is immersed in the molten metal to fill the through hole with the molten metal, and after the molten metal filling process, the molten metal tank is taken out ( Here, specifically, the substrate that has been pulled up) is cooled to solidify the molten metal in the through-hole and the molten metal that is continuously built up on the substrate from the through-hole, and through-wires and bumps And a cooling and solidifying step of forming

(Metalizing process)
First, as shown in FIG. 1, a substrate 10 is prepared, and the substrate 10 is thermally oxidized to form an oxide film as an electric insulating layer 12 on the entire substrate 10 (hereinafter, the electric insulating layer is sometimes referred to as an “oxide film”). (FIG. 2).
The through hole 11 is a fine hole having a diameter of about several tens of μm (for example, 50 μm) penetrating the substrate 10, and is opened on the front surface 13 and the back surface 14 of the substrate 10. The oxide film 12 formed by the thermal oxidation treatment of the substrate 10 is formed not only on the front surface 13 and the back surface 14 of the substrate 10 but also on the inner surface of the through hole 11.
Here, the “front surface” is a surface (one surface) directed upward in a molten metal filling step (see FIGS. 9 to 13) described later, and the “back surface” is a surface directed downward ( The other side).
In this embodiment, a case where the DRIE method is used as an example of a technique for forming a fine hole (through hole 11) in a work (substrate 10) will be described. The DRIE method of this embodiment uses sulfur hexafluoride (SF6) as an etching gas, and alternately performs etching by high-density plasma and passivation film formation on the substrate wall surface (Bosch process). Deep etching is performed to form through-holes 11 penetrating the main surfaces (front surface 13 and back surface 14) on both sides of the substrate 10.
In addition to the DRIE method, a wet etching method using the above-described etching solution, a machining method using a micro drill, or the like can be employed as a method for forming the fine hole (through hole 11) in the workpiece (substrate 10). Needless to say. When the wet etching method is applied to the formation of micropores in the silicon substrate 10, a potassium hydroxide (KOH) aqueous solution or the like is employed as an etching solution.

Next, as shown in FIG. 3, the inner surface of the through hole 11 in the front surface 13 and the back surface 14 of the substrate 10 (the inner surface of the through hole near the opening), and the opening portion of the through hole 11 in the front surface 13 and the back surface 14. A metal layer 15 is formed around the periphery by metal sputtering.
Specifically, as shown in FIG. 4, first, a first layer 15a which is a chromium (Cr) layer having a thickness of about 300 mm is formed by sputtering, and then a gold (Au) layer having a thickness of about 5000 mm. A second layer 15b is stacked on the first layer 15a. The metal layer 15 formed on the inner surface of the through hole 11 is formed from the front surface 13 or the back surface 14 of the substrate 10 to a place where it enters at least about several tens of μm toward the axial center of the through hole 11.

The metal layer 15 may be formed on the entire inner surface of the through-hole 11, ensuring wettability with the molten metal filling the through-hole 11, and ensuring the molten metal without generating voids in the through-hole 11. It is preferable to form the metal layer 15 over as wide a range as possible in the through hole 11. That is, the formation range of the metal layer 15 on the inner surface of the through hole 11 is at least several tens of inner surfaces of the through hole 11 near the through hole opening on the substrate surface 13 side (from the opening of the through hole 11 toward the central portion in the axial direction). More preferably, it is in the vicinity of the opening on both the front and back surfaces of the substrate 10 (that is, in the vicinity of both ends in the axial direction of the through hole 11. The center in the axial direction from the opening of the through hole 11 at either end. The inner surface of the through-hole 11 is most preferable.
In addition, in the formation of the metal layer 15 using sputtering, the metal layer 15 can be formed as long as the metal atoms can reach by sputtering. Therefore, the metal layer 15 can be easily formed on the inner surface of the through hole 11. There are advantages.

On the other hand, the metal layer 15 formed around the opening portion of the through hole 11 on the front surface 13 and the back surface 14 corresponds to the size of the target bump to be formed, and has a wider area (the surface of the substrate 10). 13 may be formed on the entire surface 13 and the entire back surface 14), and is patterned to a size corresponding to the bump formation range in the steps shown in FIGS.
The metal forming the first layer 15a and the second layer 15b of the metal layer 15 is not limited to the above-described chromium or gold, and may be other metals.

When the formation of the metal layer 15 is completed, as shown in FIG. 5, a photosensitive resist 16 is applied to the front surface 13 and the back surface 14 of the substrate 10, and the photosensitive resist 16 is patterned by a photolithography technique. Next, as shown in FIG. 6, the metal layer 15 (first layer 15 a and second layer 15 b) is etched and formed around the openings of the through holes 11 on the front surface 13 and the back surface 14 of the substrate 10. A metal pattern (metal layer 15) having a shape suitable for the bump size is formed. FIG. 7 shows an example of the shape of the metal layer 15 formed by patterning. Thereby, the metal layer 15 having a desired shape is formed around the opening of the through hole 11 on the front surface 13 and the back surface 14 of the substrate 10, and the metallization process is completed.
The formation of the metal layer 15 by patterning on the front surface 13 and the back surface 14 of the substrate 10 is not limited to adapting to the bump size to be formed, and for example, conforms to the ground of the pattern wiring formed on the front surface 13 and the back surface 14. The shape which forms a part etc. may be sufficient, and the shape which forms a part of pattern wiring may be sufficient.

  The workpiece (substrate 10) in which the fine holes are formed is subjected to a plasma pretreatment process before filling with molten metal. This plasma pretreatment step is cleaning for one minute with oxygen (O 2) plasma here, and the resist layer residue and foreign matters on the outer surface of the workpiece are cleaned and removed by the plasma. For this reason, uniform metal filling into the fine holes is facilitated. Note that the plasma used for cleaning is not limited to oxygen plasma, and may be hydrogen (H 2) plasma, argon (Ar) plasma, or a combination thereof. Further, this plasma pretreatment step can be performed not only before filling with molten metal but also before forming a metal layer on the workpiece.

(Molten metal filling process)
When the metallization step is completed, as shown in FIG. 8, a heat resistant film (hereinafter, the sealing material may be referred to as “heat resistant film”) is attached to the back surface 14 of the substrate 10 as the sealing material 17. The opening of the through hole 11 on the back surface 14 is closed.
As the heat resistant film, for example, a polyimide film or the like can be used. Among them, a suitable polyimide film includes Kapton (registered trademark).
In the case of Kapton, it is preferable to adopt a grade that does not harden at the temperature (melting point) of the molten metal. In this case, the Kapton is taken out from the molten metal 20 (specifically, pulled up; see FIG. 13) in the cooling and solidification step described later. There is an advantage that the heat-resistant film can be easily peeled off from the substrate 10. In addition, as the heat resistant film, a composite film obtained by bonding polyimide films such as Kapton or other resin films using a silicon-based adhesive, a tape, or the like can be used. Sealing materials (including films made of Kapton alone) that are films and tapes using Kapton can be used with one side coated with an adhesive for bonding to the workpiece. Is preferable. However, as the pressure-sensitive adhesive, a pressure-sensitive adhesive that does not become hard at the temperature (melting point) of the molten metal and can be easily peeled off from the work taken out from the molten metal is adopted.
Since the mounting operation of the sealing material 17 is performed in an atmospheric pressure environment, when the axial end of the through hole 11 is blocked by the mounting of the sealing material 17, the atmospheric pressure in the through hole 11 is atmospheric pressure. Needless to say.

  Next, as shown in FIG. 9, the substrate 10 is accommodated in the decompression chamber 18, the inside of the decompression chamber 18 is decompressed, and the substrate 10 is kept in the molten metal tank 19 in the decompression chamber 18 while maintaining the decompressed state. The molten metal 20 is stored in the molten metal 20 (see FIG. 10). The vacuum pressure here is suitably about 103 to 10-5 Pa in vacuum pressure with respect to the aspect ratio of 0.1 to 200 of the through hole 11. In FIG. 9, FIG. 10, etc., a symbol 19 a is a heater disposed around the molten metal tank 19. The substrate 10 is immersed in the molten metal 20 by attaching the substrate 10 to an elevating jig 21 installed in the decompression chamber 18 and lowering the elevating jig 21 so that the substrate 10 is kept almost horizontal. Made in the state.

The substrate 10 attached to the lifting jig 21 is lifted and lowered while the lifting jig 21 is moved up and down while maintaining almost horizontal, and the lifting of the substrate 10 from the molten metal 20 is also almost horizontal. It is done while maintaining.
The sealing material is not limited to the heat resistant film, and any material that can seal the opening of the through hole 11 in the substrate back surface 14 may be used. The shape of the sealing material is the same as that of the heat resistant film 17 described above. It is not limited to the structure bonded so that the whole 14 may be covered.
Here, the molten metal 20 is specifically obtained by heating and melting gold-tin eutectic solder (Au-20 wt% Sn), but the molten metal according to the present invention is not limited to this, and has a different composition. Gold-tin alloy, metals such as tin (Sn), indium (In), tin-lead (Sn-Pb), tin (Sn) group, lead (Pb) group, gold (Au) group, indium A solder such as an (In) group or an aluminum (Al) group can also be used. However, the metal layer (especially the surface layer) and the molten metal are selected as a combination that can ensure sufficient wettability.

  The substrate 10 is immersed in the molten metal 20 with the back surface 14 to which the sealing material 17 is attached being the lower side and the front surface 13 being the upper side, so that the entire substrate 10 is not exposed so that the substrate surface 13 is not exposed. Buried inside. However, at this stage, the flow of the molten metal 20 into the through-hole 11 that is a fine hole with a high aspect ratio of about several tens of μm that penetrates the substrate 10 having a thickness of about several hundred μm is hardly started.

When the immersion of the substrate 10 in the molten metal 20 is completed, the inside of the decompression chamber 18 is pressurized. As shown in FIG. 11A, in the through hole 11 into which the molten metal 20 does not flow before pressurization in the decompression chamber 18, the molten metal 20 that blocks the opening (opening on the substrate surface 13 side). Since the reduced pressure state is maintained by the sealing material 17 and the pressure inside the decompression chamber 18, the molten metal 20 can surely flow into and fill the through hole 11 (FIG. 11B). ), See FIG. The pressurization here should just be more than atmospheric pressure. At this time, since the wettability of the molten metal 20 is ensured by the metal layer 15 formed on the inner surface of the end portion of the through hole 11 on the substrate back surface 14 side, the end portion of the through hole 11 on the substrate back surface 14 side. Even in the vicinity, the molten metal 20 is well adapted to the inner surface of the through hole 11 and is filled in the through hole 11 without a gap, so that the molten metal 20 can be reliably filled in the entire through hole 11.
The pressurization in the decompression chamber 18 can also be performed by feeding an inert gas such as nitrogen gas into the decompression chamber 18, and in this case, the inert metal atmosphere is applied to the molten metal before solidification. There is an advantage that oxygen entrapment and the like can be prevented to prevent deterioration of characteristics of the molten metal on the substrate 10 and in the through hole 11.

(Cooling solidification process)
When the filling of the molten metal 20 into the through hole 11 is completed, the substrate 10 is pulled up from the molten metal 20 as shown in FIG. At this time, since the state where the opening on the substrate back surface 14 side of the through hole 11 is closed by the heat resistant film 17 is maintained, the molten metal 20 in the through hole 11 does not fall out of the substrate back surface 14. Further, the molten metal 20 filled in the through-hole 11 due to the wettability of the molten metal 20 to the metal layer 15 formed on the inner surface of the through-hole 11 near the opening on the substrate surface 13 side and the periphery of the opening. However, there is no inconvenience that the molten metal 20 flows out from the opening of the through hole 11 on the substrate surface 13 side.

On the surface 13 of the substrate 10 pulled out from the molten metal 20, the molten metal 20 remains attached without falling along the metal pattern (metal layer 15) formed in the metallization process. In regions other than the metal pattern, the wettability of the molten metal 20 with respect to the substrate 10 is poor, and therefore the molten metal 20 falls as the substrate 10 is pulled out of the molten metal 20.
For example, as shown in FIG. 7, when an annular metal layer 15 is formed around the opening of the through hole 11 corresponding to the bump shape, the existence region of the metal layer 15 and the opening of the through hole 11 is present. On the substrate surface 13, the molten metal 20 continuous from the through-hole 11 becomes a build-up state on the presence region of the metal layer 15 and the existence region of the opening of the through-hole 11.

When the substrate 10 is pulled up from the molten metal 20, the substrate 10 is cooled to solidify the molten metal 20 filled in the through holes 11 and the above-described molten metal 20 in the build-up state. Thereby, as shown in FIG. 14, the through wiring 22 formed by solidifying the molten metal 20 in the through hole 11 and the bump 23 protruding on the substrate surface 13 are integrally formed, and the filled metal portion ( A substrate with through wiring (corresponding to the member with filled metal portion according to the present invention) in which the through wiring 22) and the external metal portion (bump 23) are formed is obtained.
As described above, it is possible to prevent the molten metal 20 from flowing out of the through hole 11 due to the pulling up of the substrate 10 from the molten metal 20 and to reliably maintain the filled state of the molten metal 20 in the through hole 11. The through wiring 22 having no defects such as the above can be obtained with certainty. Moreover, since the molten metal 20 that is in the built-up state on the metal layer 15 and the region where the opening of the through-hole 11 is formed has a mountain shape due to its surface tension or the like, the substrate surface is obtained by cooling and solidifying it. A chevron-shaped bump 23 protruding on the surface 13 is formed.

  As described above, in the configuration in which the through wiring 22 and the bump 23 are integrally formed, there is no problem of bonding failure and the like as compared with the configuration in which the bump is formed separately from the through wiring and bonded to the through wiring. The characteristics can be reliably secured. In addition, there is a problem such as a brittleness of the joint portion (joint portion between the bump and the penetrating wiring) due to the difference in thermal expansion coefficient or the diffusion of the material which occurs when the bump and the penetrating wiring are made of different materials. And long-term reliability can be improved.

FIG. 15 shows, as a comparative example, an example in which the molten metal filling step and the cooling and solidifying step are performed without forming the metal layer 15 on the substrate, that is, without performing the metallization step.
In FIG. 15, the substrate 3 is the same as the substrate 10 described in the present embodiment. In FIG. 15, the molten metal denoted by reference numeral 2 is the same as the molten metal 20 described in the present embodiment. Also in this case, the molten metal 2 could be filled in the entire through hole 1 of the substrate 3 in the molten metal filling step, but when the substrate 3 was pulled up from the molten metal in the molten metal tank 19, the molten metal was removed from the through hole 1. As a result, the molten metal 2 in the through hole 1 becomes insufficiently filled, and the upper surface of the molten metal 2 is lowered by several μm to several tens of μm downward from the surface 4 of the substrate 3 which is the upper side when it is pulled up. A case of forming a step D is confirmed. Therefore, in the method for forming a through wire according to the present invention, the metal layer 15 formed on the inner surface near the opening of the through hole and around the opening of the through hole on the substrate surface exhibits an effect of preventing the molten metal from flowing out. It is clear that

  In the method for forming a through-wiring according to the present invention, the metal layer is formed only on the inner surface near the opening of the through hole, and the formation of the metal layer around the opening of the through hole on the substrate surface is omitted. However, although it is difficult to form a sufficiently large bump, it is possible to prevent the molten metal from flowing out of the through-hole due to the lifting of the substrate from the molten metal. There is no inconvenience such as generation of a step due to lack. In this case, for example, when a bump to be bonded to the through wiring is formed in a separate process, an effect such as occurrence of bonding failure can be extremely reduced.

(Second Embodiment)
Next, a second embodiment of the present invention will be described.
The metal filling method of this embodiment employs a substrate on which non-through holes 51 (fine holes) are formed as the workpiece 50 (hereinafter, the workpiece may be referred to as “substrate”). This is a method of forming a filled metal portion and bumps obtained by solidifying the molten metal filled in the metal.

As shown in FIG. 16, in this embodiment, as the substrate 50, a configuration using a glass substrate in which a plurality of non-through holes 51 that are fine holes are formed is illustrated, but other than the non-through holes 51 of the substrate 50. The configuration (material, etc.) can be the same as that of the substrate 10 of the first embodiment.
The plurality of non-through holes 51 formed in the substrate 50 function as inner via holes or the like. The inner diameter of the non-through hole 51 may be the same as that of the through hole 11 (fine hole) of the substrate 10 of the first embodiment. All of the non-through holes 51 formed in the substrate 50 are opened on one surface (here, the front surface 53) of the substrate 50, and are directed almost straight from the opening portion on the front surface 53 toward the back surface 54 of the substrate 50. It is formed to extend.

In this metal filling method, using the substrate 50, the metallization process, the molten metal filling process, and the cooling and solidifying process are performed in the same order as in the first embodiment. However, the micro hole 51 of the substrate 50 used in this metal filling method is a non-through hole, and only one end portion along the axial direction is opened on the outer surface of the substrate 50 (here, the surface 53), and along the axial direction. Since the other end portion is closed, the sealing material is used in the operation of taking out the substrate 50 that has been crushed in the molten metal 20 in the molten metal filling step from the molten metal 20 (specifically, lifting can be adopted). There is no need to use it. In this metal filling method, the metallizing step, the molten metal filling step, and the cooling and solidifying step are advanced in the same manner as in the first embodiment except that the attachment and removal of the sealing material to the substrate 50 are omitted. It has become. Further, the plasma pretreatment process and the like are performed in the same manner as in the first embodiment.
Furthermore, in the metal filling method described here, a filling metal portion exposing step (described later) for exposing the filling metal portion on the back side of the substrate is added after the cooling and solidifying step.

FIG. 17 is a view showing the substrate 50 that has been subjected to the metallization process. Reference numeral 52 denotes an electrical insulating layer such as an oxide film, and reference numeral 55 denotes a metal layer. The metal layer 55 is formed around the inner surface of the minute hole 51 and the opening of the minute hole 51 on the surface 53 of the workpiece 50. The formation range for the inner surface of the minute hole 51 is the same as that of the metal layer in the first embodiment. Then, it is formed from the opening of the fine hole 51 to a place where it enters at least about several tens of μm from the fine hole 51 toward the back side.
FIG. 18 is a diagram showing a state in which the substrate 50 is crushed in the molten metal in the metal filling step, and is crushed in the molten metal 20 in the molten metal tank 19 installed in the decompression chamber 18. Indicates. The metal filling step is the same as in the first embodiment, except that the use of the sealing material can be omitted as shown in this figure.
FIG. 19 shows a cooling and solidification process in which the substrate 50 taken out from the molten metal 20 is cooled and protrudes on the substrate 50 in the vicinity of the molten metal 20 filled in the micro holes 51 and the openings of the micro holes 51. A state in which the filled metal portion 56 and the external metal portion 57 (such as a bump) integrated with the filled metal portion 56 are formed by solidification of the molten metal 20 that has been built up is shown. The substrate 50 shown in FIG. 19, that is, the substrate 50 on which the filling metal portion 56 and the external metal portion 57 are formed is the member with the filling metal portion according to this embodiment.
FIG. 20 is a view showing the filled metal portion exposing step, and shows a state where the back surface side of the substrate 50 that has completed the cooling and solidifying step is polished to expose the filled metal portion 56 in the microhole 51. Thereby, the filling metal part 56 can also function as a through wiring of the substrate 50 or the like. The board | substrate shown in FIG. 20 is also a member with a filling metal part which concerns on this embodiment.
As a method of exposing the filling metal portion 56 on the back surface side of the substrate 50, various methods other than polishing, such as partial removal of the substrate 50 by wet etching, can be employed.

(Third embodiment)
Next, a third embodiment of the present invention will be described.
21 employs a rod-like member (hereinafter, the workpiece may be referred to as a “rod-like member”) as the workpiece 24, and has a diameter of 0. The same method as in the first embodiment (a metallizing step, a molten metal filling step, and a cooling and solidifying step are sequentially performed in the through-hole 25 having a length of 1 mm and a total length of 5 mm. In this example, the filling metal portion 26 and the external metal portion 27 are formed by filling tin as a molten metal by using the substrate 28 as the substrate surface and the opposite surface as the substrate back surface. Various methods such as the above-mentioned DRIE method can be adopted as a method for forming a through hole in the work 24.
The workpiece 24 (rod-like member) is a glass rod here, but is not limited to this. For example, the workpiece 24 is formed of one material selected from ceramic, silicon, various synthetic resins, or glass. A material formed by combining two or more materials selected from ceramic, silicon, synthetic resin, and the like can be used. The kind of metal layer 15, the forming method, the heat resistant film 17 and the like are the same as described above. However, the formation range of the metal layer 15 is in a range of about 2 to 3 times the diameter of the through hole 25 from both axial ends of the through hole 25 toward the central part in the axial direction, on both side surfaces facing the axial direction of the rod-shaped member 24. The area around the opening of the through hole 25 was set to a range of several mm from the outer periphery of the opening.

  The method of filling the through hole 25 with the molten metal is the same as the molten metal filling step described above, except that the rod-like member 24 is crushed and pulled up with respect to the molten metal stored in the molten metal tank 19 in the decompression chamber 18. Is performed with the heat resistant film 17 side down. Referring to FIG. 22 (FIG. 22 shows a state in which the workpiece 24 is pulled up from the molten metal 20), the workpiece 24 having completed the formation of the metal layer 15 is attached to the lifting jig 21 in the decompression chamber 18. The elevating and lowering drive of the elevating jig 21 causes the through hole 25 to be raised and lowered in the decompression chamber 18 while maintaining the vertical posture. However, the work 24 is accommodated in the decompression chamber 18 with an opening at the other end in the axial direction facing the one end in the axial direction of the through hole 25 directed upward when accommodated in the decompression chamber 18. Before the sealing, the sealing material 17 is used to block the material in advance. When the work 24 is accommodated in the decompression chamber 18, the inside of the decompression chamber 18 is decompressed, and the work 24 is lowered while maintaining the decompressed state, and is stored in the molten metal tank 19 in the decompression chamber 18. It is immersed in the molten metal 20. Next, while maintaining the state where the work 24 is immersed in the molten metal 20, the inside of the vacuum chamber 18 is pressurized to fill the through hole 25 with the molten metal. Next, the workpiece 24 is raised and pulled up from the molten metal 20 and cooled.

Also in this example, similarly to the case of the substrate 10 described above, it was possible to reliably fill the entire through hole 25 with the molten metal. Further, the opening portion of the through hole 25 on the upper surface 28 of the work 24 taken out (specifically, pulled up) from the molten metal 20 (the side surface of the work 24 on the side where one end portion of the through hole 25 is opened) On the region where the metal layer 15 around the opening is present, the molten metal 20 continuous from the through-hole 25 is in a built-up state, and the inside of the through-hole 25 is cooled by cooling the work 24 pulled up from the molten metal 20. The filled metal portion 26 formed by solidifying the molten metal 20 and the external metal portion 27 formed by solidifying the above-described molten metal 20 can be integrally formed, and the filled metal portion 26 and the external metal portion 27 can be integrally formed. The member with a filling metal part which has these was obtained.
A solid filled metal portion 26 having no voids could be formed inside the obtained member with the filled metal portion. In addition, the diameter (inner diameter) of the through hole 25 is considerably larger than the through hole 11 of the substrate 10 described above, but the filled metal portion 26 fills the entire through hole 25 including one end portion in the axial direction of the through hole 25. In this example, there is no step where the tip of the filling metal part 26 falls from the side surface of the work 24 at one end of the through hole 25 in the axial direction. It is considered that the outflow of the molten metal from the through hole 25 at the time of pulling up is prevented.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described.
In this embodiment, it is the same that the same rod-like member as the third embodiment (hereinafter, the workpiece may be referred to as a rod-like member) is adopted as the workpiece 30. However, as shown in FIG. A fine hole 31 formed along the axial direction opens only at one axial end of the rod-shaped member 30 and does not open at the other axial end (hereinafter referred to as a fine through hole). It is different in that it may be called.

Similarly to the third embodiment, the metal filling method of this embodiment is performed in the order of the metallization step, the molten metal filling step, and the cooling and solidifying step, but the fine holes 31 formed in the workpiece 30 are non-through holes. Therefore, it is not necessary to use a sealing material.
FIG. 23 shows the work 30 that has completed the cooling and solidifying process. As shown in FIG. 23, the work 30 on which the filling metal part 26 and the external metal part 27 are formed has the filling metal part according to this embodiment. It is a member. Moreover, in the metal filling method of this embodiment, the filling metal part exposure process is added after the cooling solidification process, and the filling metal part 26 can be exposed also to the other end side of the shaft method of the rod-shaped member 30. That is, if the metal filling portion 26 is exposed by removing the lower side from the virtual line 32 in FIG. 23 of the member with the filling metal portion (or only the workpiece 30) shown in FIG. The part 26 can be used as a through wiring or the like.

In addition, this invention is not limited to the said embodiment, A various change is possible.
For example, the method for forming the metal layer is not limited to the above-described sputtering, and a plating method (substrate is immersed in a plating solution) or the like can also be employed.
Regarding the metal filling method according to the present invention, the substrate and the rod-like member are exemplified as the workpiece in the above embodiment, but the present invention is not limited to this, and various specific shapes, materials, etc. of the workpiece can be adopted.
As shown in the drawings, etc., the board and workpiece should be immersed in the molten metal and removed from the molten metal in a posture with the through hole closed by the heat-resistant film as the sealing material. For example, depending on conditions such as the wettability between the metal layer formed on the inner surface near the opening of the through-hole and the molten metal flowing into the through-hole and the fluidity of the molten metal, It is possible to secure a large degree of freedom in the posture at the time of immersion and the posture at the time of taking out (pull-up).

It is a figure which shows 1st Embodiment of this invention, Comprising: It is sectional drawing which shows the prepared board | substrate. It is sectional drawing which shows the state which formed the oxide film as an electrically insulating layer by carrying out the thermal oxidation process of the board | substrate of FIG. It is sectional drawing which shows the state which formed the metal layer in the board | substrate after the thermal oxidation process of FIG. It is sectional drawing which shows the detail of the metal layer of FIG. It is sectional drawing which shows the state which coated the photosensitive resist on the board | substrate in which the metal layer of FIG. 3 was formed. It is sectional drawing which shows the state which removed the photosensitive resist from the board | substrate of FIG. It is a perspective view which shows an example of shaping | molding by the patterning of the metal layer on a substrate surface. It is a figure which shows the state which affixed the heat resistant film on the back surface of the board | substrate which completed the patterning of the metal layer of FIG. 7, and blocked the opening part of the through-hole. It is sectional drawing which shows the pressure reduction chamber applied to the formation method of the penetration wiring which concerns on this invention. FIG. 10 is a diagram showing a state in which a substrate is crushed in a molten metal stored in a molten metal tank installed in the decompression chamber of FIG. 9. (A) is sectional drawing which shows the state which the substrate was crushed in the molten metal in the state which decompressed the inside of a decompression chamber, (b) is the state which pressurized the inside of a decompression chamber and filled the molten metal into the through-hole of the board | substrate. It is sectional drawing shown. It is sectional drawing which shows the state of FIG.11 (b) in detail. It is a figure which shows the state which pulled up the board | substrate from the molten metal currently stored in the molten metal tank installed in the pressure reduction chamber of FIG. It is sectional drawing which shows the state which cooled the board | substrate pulled up out of molten metal, and formed the penetration wiring and the bump. It is sectional drawing which shows the penetration wiring formed in the through-hole of a board | substrate by the formation method of the penetration wiring of a comparative example. It is sectional drawing which shows the board | substrate applied to 2nd Embodiment of this invention. It is sectional drawing which shows the state which completed the metallization process of the board | substrate of FIG. FIG. 17 is a diagram illustrating a state in which the substrate of FIG. 16 is crushed in a molten metal in a metal filling step after completion of a metallization step, and is crushed in a molten metal in a molten metal tank installed in a vacuum chamber. Indicates the state. FIG. 19 is a cross-sectional view showing a state in which, after the metal filling step of FIG. 18 is completed, the cooling of the substrate taken out from the molten metal is completed in the cooling and solidification step to form a filled metal portion and an external metal portion. FIG. 20 is a cross-sectional view showing a state where the back side of the substrate is polished in the filled metal portion exposing step after the cooling and solidifying step in FIG. 19 is completed to expose the filled metal portion in the fine holes. It is a figure which shows 3rd Embodiment of this invention, and is sectional drawing which shows the example which formed the filling metal part and the external metal part in the rod-shaped member by which the through-hole was pierced with the metal filling method which concerns on this invention. is there. It is a figure which shows the process of filling a molten metal to the through-hole of the rod-shaped member of FIG. 21, Comprising: The figure which shows the state which pulled up the board | substrate from the molten metal stored in the molten metal tank installed in the decompression chamber It is. It is a figure which shows 4th Embodiment of this invention, and sectional drawing which shows the example which formed the filling metal part and the external metal part in the rod-shaped member by which the non-through-hole was pierced with the metal filling method which concerns on this invention It is.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Work (board | substrate), 11 ... Fine hole (through-hole), 13 ... Front surface (one side), 14 ... Back surface (the other side), 15 ... Metal layer, 17 ... Sealing material (heat resistant film), DESCRIPTION OF SYMBOLS 18 ... Depressurization chamber, 19 ... Molten metal tank, 20 ... Molten metal, 22 ... Filling metal part (penetration wiring), 23 ... External metal part (bump), 24 ... Workpiece (rod-shaped member), 25 ... Fine hole (through hole) ), 26... Filled metal part, 27... External metal part, 28... Upper surface, 30... Work (bar-shaped member), 31. Non-through hole), 53... Front surface (one surface), 54. Back surface (the other surface), 55... Metal layer, 56.

Claims (3)

  The fine holes (11, 25) formed in the work (10, 24) have filled metal portions (22, 26) formed by filling the fine holes with molten metal, and the inner surfaces of the fine holes The metal layer (15) is formed in a range including at least an inner surface located at an end portion opened to the outer surface of the workpiece of the fine hole, and the metal layer of the fine hole is formed in the filling metal portion. The inside of the micropore is filled so that the electrical conduction is ensured including the end of the micropore, and one end is overlaid and the other end is flat. A member with a filling metal part, wherein a through electrode satisfying the above and a bump made of the above-described build-up are integrally formed.   2. The member with a filled metal portion according to claim 1, wherein the workpiece is a semiconductor substrate, and an insulating layer is provided on an inner surface of a fine hole with which the through electrode is in contact.   The said workpiece | work is a semiconductor substrate, The insulating layer is provided in the inner surface of the fine hole which the said penetration electrode contacts, and the one surface where the said build-up part contacts, The Claim 1 characterized by the above-mentioned. A member with a filled metal part.

Images