JP2006203170A - Metal filling device and metal filling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a metal oxide on the surface of a molten metal from being attached to a substrate to improve yield and quality in a molten metal filling method. <P>SOLUTION: In the metal filling device 10A provided with a chamber 11 having depressurizing means 14a, 14b that depressurize the inside of the chamber and pressurizing means 15a, 15b that pressurize the inside of the chamber, and a metal melting device 16 that can heat and melt a metal in the chamber 11, and fills the metal in fine holes formed in the substrate 2, a metal surface purifying mechanism 20 that keeps the surface 7 of the heated and molten metal 6 clean is provided in the metal melting device16. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a metal filling apparatus and a metal filling method for filling a metal into a microscopic hole formed in a substrate, for example, a wiring for an electronic device or an optical device, and a structure of a MEMS (Micro Electro Mechanical Systems) device. The present invention relates to a metal filling apparatus and a metal filling method suitable for the above.

In general, a metal filled in micropores may be used for wiring of various devices such as an electronic device and an optical device, and a structure constituting a MEMS device (see, for example, Patent Document 1).
FIG. 3 is a cross-sectional process diagram for manufacturing the substrate 1 with a through electrode for use in wiring of an electronic device or the like as an example. In the substrate 1 with a through electrode shown in FIG. 3D, a fine hole 4 penetrating the main surfaces 3 and 3 of the substrate 2 is formed in a substrate 2 made of a semiconductor material such as silicon or an insulating material such as glass. The fine holes 4 are filled with a conductive material 5 such as metal.

  In order to manufacture the substrate 1 with a through electrode, first, as shown in FIG. 3A, a fine hole forming step for forming a fine hole 4 penetrating the substrate 2 in the substrate 2 is performed. As a method of forming the micropores 4, there are a Deep-Reactive Ion Etching (DRIE) method represented by an ICP-RIE (Inductively Coupled Plasma-Reactive Ion Etching) method, a wet etching method using an etching solution, and a mechanical processing by a micro drill. Law. Further, when a semiconductor substrate such as silicon is used as the substrate 2, an insulating layer (not shown) is formed on the side wall (inner surface) of the microhole 4 as necessary.

Next, as shown in FIG. 3B to FIG. 3D, a metal filling step of filling the micro holes 4 with a metal is performed using a molten metal filling method (see, for example, Patent Document 2).
First, as shown in FIG. 3B, the substrate 2 in which the micropores 4 are formed is immersed in the molten metal 6 in a chamber (not shown) maintained at a first pressure lower than the atmospheric pressure. .
Next, as shown in FIG. 3C, the pressure in the chamber is increased to a second pressure higher than the first pressure. Due to the pressure difference generated at this time, the metal 5 is filled with the differential pressure into the fine holes 4.
Next, as shown in FIG. 3D, after the substrate 2 in which the fine holes 4 are filled with the metal 5 is taken out from the molten metal 6, the metal 5 filled in the fine holes 4 is cooled by cooling. The substrate 1 with through electrodes is solidified.
JP 2000-195861 A JP 2004-103867 A

  As described above, the molten metal filling method is a very effective means as a method for filling the fine holes with metal. However, although the process is performed while maintaining the inside of the chamber under reduced pressure or an inert gas atmosphere such as nitrogen gas, when using a solder containing a metal element that is easily oxidized such as tin (Sn), It was impossible to completely prevent oxidation of the surface 7 of the molten metal 6. Therefore, in the conventional molten metal filling method, when the substrate 2 is immersed in the molten metal 6 and pulled up, the metal oxide generated on the surface 7 of the molten metal 6 becomes the main surface 3 and the fine holes 4 of the substrate 2. Adhering to the inner surface may cause problems such as poor filling of the metal, contamination of the substrate, bridges between the fine holes 4 and 4 and the like, resulting in a decrease in yield.

  The present invention has been made in view of the above circumstances, and it is possible to prevent the metal oxide on the surface of the molten metal from adhering to the substrate for the purpose of improving the yield and quality in the molten metal filling method. It is an object to provide a metal filling apparatus and a metal filling method.

In order to solve the above-mentioned problems, the present invention includes a chamber having a decompression means for decompressing the interior and a pressurization means for pressurizing the interior, and a metal melting apparatus capable of heating and melting the metal in the chamber. In the metal filling apparatus for filling a metal into the micropores formed in the substrate, the metal melting apparatus includes a metal surface purification mechanism that keeps the surface of the heated and melted metal clean. provide.
In the metal filling apparatus according to the present invention, the metal surface purification mechanism may include a jet pump that generates a flow along the surface of the heat-melted metal. In this case, the metal surface purification mechanism includes a second tank provided inside the molten metal tank in which the metal melted by heating in the metal melting apparatus is stored, and the upper edge of the second tank is It protrudes above the surface of the molten metal stored outside the second tank, and the jet pump melts into the second tank through an intake port that opens at the lower part of the second tank. It is preferable to generate a flow for taking in the metal.
Further, in the metal filling device according to the present invention, the metal surface purification mechanism pushes and removes dirt on the surface of the molten metal by moving along the surface of the molten metal. A thing provided with a dirt removal member can be used.
The chamber is preferably configured such that the interior of the chamber is divided into two or more rooms, or two or more chambers are connected.
It is preferable that at least one mechanism for heating the substrate is provided in at least one room of the chamber or in at least one chamber.

The present invention is also a metal filling method for filling a metal into a microscopic hole formed in a substrate using the above-described metal filling apparatus, wherein the substrate is subjected to the metal surface under a first pressure lower than atmospheric pressure. A step of immersing in a molten metal whose surface is kept clean by a purification mechanism; a step of increasing the first pressure to a second pressure higher than this and filling the molten metal with a differential pressure; And a step of pulling up the substrate from the molten metal.
In the metal filling method of the present invention, it is preferable that the substrate is heated in advance to a temperature comparable to the temperature of the molten metal before immersing the substrate in the molten metal.

  According to the present invention, by using a metal surface purification mechanism, dirt such as metal oxide generated on the surface of the molten metal is removed, and the surface of the molten metal is always kept clean where the substrate is immersed and pulled up. be able to. Therefore, it is possible to prevent the dirt from adhering to the substrate and improve the yield and quality in the molten metal filling method.

The present invention will be described below with reference to the drawings based on the best mode.
FIG. 1 is a schematic configuration diagram showing a first embodiment of the metal filling apparatus according to the present invention, and FIG. 2 is used to fill the metal in the fine holes formed in the substrate using the metal filling apparatus shown in FIG. It is explanatory drawing explaining a method. FIGS. 3A to 3D are cross-sectional process diagrams for explaining a metal filling process for filling a metal into a microhole using a molten metal filling method. 1 and 2 are both cross-sectional views when the metal filling device is viewed from the front.

  As shown in FIG. 1, the metal filling apparatus 10A of the present embodiment includes a chamber 11, decompression means 14a and 14b for decompressing the inside of the chamber 11, pressurization means 15a and 15b for pressurizing the interior of the chamber 11, The metal melting device 16 capable of heating and melting the metal in the chamber 11 and the substrate 2 (see FIG. 3 for details) in which the fine holes 4 are formed are held, and the substrate 2 is melted by the metal melting device 16. A conveying jig 17 provided so as to be able to freely reciprocate between a state located outside the metal 6 (see FIG. 1) and a state immersed in the molten metal 6 (see FIG. 2); And a metal surface purification mechanism 20 that keeps the surface 7 of the metal 6 heated and melted in the metal melting device 16 clean.

In this embodiment, the chamber 11 is divided into two upper and lower chambers 11 a and 11 b by a partition plate 12. Among these, the metal melting apparatus 16 is installed in the 2nd chamber 11b located in the lower side. The first chamber 11a located above the second chamber 11b is provided with an opening / closing valve (not shown) that serves as an entrance for carrying the substrate 2 into and out of the chamber 11. Yes.
In each of the first chamber 11a and the second chamber 11b, as decompression means 14a and 14b for decompressing the interior of each of the rooms 11a and 11b, an evacuation system including a rotary pump and the inside of each of the rooms 11a and 11b As the pressurizing means 15a and 15b for pressurizing the gas, a gas supply system for supplying an inert gas (atmosphere gas) such as nitrogen gas is connected. That is, the two chambers 11a and 11b can be decompressed and pressurized independently of each other.
In this embodiment, the evacuation system and the gas supply system are provided independently for the two chambers 11a and 11b. However, the common evacuation system (decompression means) and / or the gas supply system (pressurization) It is also possible to change the flow path of the exhaust gas and / or the gas supply by piping and a switching valve.

The partition plate 12 includes an opening / closing valve 13 at a position where the transport jig 17 and the substrate 2 fixed thereto can freely move between the first chamber 11a and the second chamber 11b.
When the transfer jig 17 is moved between the first chamber 11a and the second chamber 11b, the passage of the transfer jig 17 is secured by opening the opening / closing valve 13.
When the inside of the chamber 11 is divided into a first chamber 11 a that can be opened to transport the substrate 2 inside and outside the chamber 11 and a second chamber 11 b that includes a metal melting device 16, the first chamber In order to prevent the second chamber 11b from being completely exposed to the atmosphere by closing the opening / closing valve 13 when the opening 11a is opened to the atmosphere outside the chamber 11, significant oxidation of the molten metal 6 in the metal melting apparatus 16 can be prevented. In addition, it is possible to prevent large foreign matters from being mixed into the molten metal 6.

The metal melting apparatus 16 includes a molten metal tank 16a in which the heated and melted metal 6 is stored, a heater (not shown) for heating the molten metal 6, and a temperature controller (not shown) for controlling the temperature of the molten metal 6. .
Here, as the molten metal 6, a single metal or an alloy such as solder can be used. Specific examples include metals such as tin (Sn) and indium (In); gold tin (Au—Sn) series, tin lead (Sn—Pb) series, tin (Sn) group, lead (Pb) group, gold ( A solder such as an Au) group, an indium (In) group, or an aluminum (Al) group can be used.

  The metal surface purification mechanism 20 in the present embodiment includes a jet pump 21 and a second tank 22 provided inside the molten metal tank 16 a in the metal melting device 16. The upper edge 23 of the second tank 22 protrudes above the surface 7 of the molten metal 6 stored outside the second tank 22, and the jet pump 21 opens to the lower part of the second tank 22. A flow for taking the molten metal 6 into the second tank 22 through the intake port 24 is generated. Therefore, by operating the jet pump 21, the molten metal 6 inside the second tank 22 always overflows out of the second tank 22. That is, a flow along the surface of the metal heated and melted by the operation of the jet pump 21 is generated, and the dirt 8 such as metal oxide generated on the surface 7 of the molten metal 6 in the second tank 22 is removed from the second tank. The surface 7 of the molten metal 6 can always be kept clean in the second tank 22 by flowing out to the outside of the second tank 22.

Next, a method for filling the metal 5 in the micro holes 4 of the substrate 2 by the molten metal filling method using the metal filling apparatus 10A of this embodiment will be described.
First, as shown in FIG. 3A, the substrate 2 on which one or a plurality of fine holes 4 are formed is fixed to the transport jig 17 and installed in the first chamber 11a.
As a specific example of the substrate 2, a silicon substrate having a thickness of about 50 μm is penetrated with respect to a silicon substrate having a thickness of 300 μm by Deep-Reactive Ion Etching (DRIE) method so as to penetrate both main surfaces 3 and 3 of the silicon substrate 2. What formed the fine hole 4, 4, ... can be used.

  Here, the DRIE method uses sulfur hexafluoride (SF6) as an etching gas, and alternately performs etching by high-density plasma and passivation film formation on the sidewalls of the fine holes (Bosch process). The substrate 2 is deeply etched. In the case of a silicon substrate, a thin insulating layer (not shown) made of silicon oxide (SiO 2) is formed on the main surfaces 3 and 3 of the silicon substrate 2 and on the hole walls of the fine holes 4 by a passivation film forming process.

The substrate 2 on which the microholes 4 are formed is not limited to a silicon substrate, but may be another semiconductor substrate such as gallium arsenide (GaAs) or an insulating substrate such as glass.
Further, the fine hole 4 may be a non-through hole, and the diameter and depth thereof can be appropriately set according to the thickness of the substrate 2 and a desired application. Furthermore, the cross-sectional shape perpendicular to the depth direction of the micropore may be any shape such as a circle, an ellipse, a triangle, a quadrangle, and a rectangle. Further, the method for forming the fine holes is not limited to the DRIE method, and a wet etching method using a potassium hydroxide (KOH) aqueous solution or the like, a machining process using a micro drill, a photoexcited electrolytic polishing method, or the like can be used.

The second chamber 11b is evacuated by the decompression means 14b connected to the second chamber 11b and kept in a decompressed state in advance. Prior to transporting the substrate 2 to the second chamber 11b, the decompression means 14a connected to the first chamber 11a is used until the pressure in the first chamber 11a reaches the same level as the second chamber 11b. After the pressure is reduced, the opening / closing valve 13 is opened. Further, the transfer jig 17 holding the substrate 2 is moved to the second chamber 11b through the open / close valve 13 that is open.
In a state where the first chamber 11a and the second chamber 11b are depressurized to a first pressure lower than the atmospheric pressure, the substrate 2 is moved to the molten metal 6 in the second tank 22 as shown in FIG. Immerse in. By the operation of the jet pump 21 of the metal surface purification mechanism 20, the surface 7 of the molten metal 6 is always kept clean in the second tank 22, thereby preventing the dirt 8 from adhering to the substrate 2.
The first pressure is, for example, about 10 Pa, but is not particularly limited to this, and any pressure may be used as long as the pressure is lower than the atmospheric pressure.
In the examples, a gold-tin alloy (Au 80% by mass—Sn 20% by mass) was used as the molten metal 6. However, the present invention is not particularly limited thereto, and an appropriate metal or alloy can be used as described above.

Next, nitrogen gas is supplied into the chamber 11 by the pressurizing means 15a and 15b, and the pressure inside the first chamber 11a and the second chamber 11b is increased to a second pressure higher than the first pressure. Then, the molten metal 5 is filled into the micro holes 4 with a differential pressure.
Here, the significance of the differential pressure filling will be described as follows. Just immersing the substrate 2 in the molten metal 6 may cause a space in which the metal is not filled in the fine holes 4 as shown in FIG. Although the pressure in this space is the first pressure, if the external pressure of the molten metal 6 is increased to the second pressure after the substrate 2 is immersed in the molten metal 6, the micropores of the substrate 2 immersed in the molten metal 6 4, which is equal to the first pressure, and the external pressure outside the molten metal 6 (which is equal to the second pressure), the molten metal flows into the micropores 4, and the molten metal 6 can be pressure-filled into the fine holes 4.
The second pressure may be any pressure as long as it is higher than the first pressure, and may be pressurized until it becomes equal to atmospheric pressure, or may be pressurized to a pressure higher than atmospheric pressure, for example.

Next, the position of the conveying jig 17 is moved to the first chamber 11a side as shown in FIG. 1, and the substrate 2 is pulled out of the molten metal 6 and cooled as shown in FIG. 3 (d). Thereby, the metal 5 filled in the fine holes 4 is solidified, and the substrate 1 in which the fine holes 4 are filled with the metal 5 is obtained.
After closing the opening / closing valve 13 of the partition plate 12 and evacuating the second chamber 11 b, the first chamber 11 a is opened, and the substrate 2 is removed from the transfer jig 17.
When the second pressure is different from the atmospheric pressure (more precisely, the pressure outside the chamber 11), the decompression means 14a connected to the first chamber 11a or the pressurization is performed before opening the first chamber 11a. It is desirable to balance the internal pressure of the first chamber 11a with the atmospheric pressure using the means 15a. On the other hand, when the second pressure is equal to the atmospheric pressure, the first chamber 11a can be opened immediately.
The metal 5 filled in the fine holes 4 as described above can be used as a through electrode that electrically connects the front and back of the substrate 2 or as a part of a structure in the MEMS device.

As described above, the metal filling apparatus 10A according to the present embodiment uses the metal surface purification mechanism 20 so that the surface of the molten metal 6 is located inside the second tank 22 where the substrate 2 is immersed and pulled up. 7 can always be kept clean. Accordingly, it is possible to prevent dirt 8 such as metal oxide on the surface 7 of the molten metal 6 from adhering to the main surface 3 of the substrate 2 or the hole walls of the fine holes 4 and improve the yield and quality in the molten metal filling method. It becomes possible.
Since the metal surface purification mechanism 20 includes a jet pump 21 that generates a flow along the surface 7 of the heated and melted metal 6, even when the substrate 2 is immersed in the molten metal 6 as shown in FIG. The presence of the conveying jig 17 does not get in the way, and the dirt 8 on the surface 7 of the molten metal 6 can be removed.
Further, the second tank 22 is provided inside the molten metal tank 16 a in which the molten metal 6 is stored, and the molten metal 6 in the second tank 22 flows out of the second tank 22. The dirt 8 on the surface 7 of the molten metal 6 can be removed out of the second tank 22 along with the flow of the molten metal 6, and the dirt 8 is prevented from returning to the inside of the second tank 22. Can do.

As mentioned above, although this invention has been demonstrated based on suitable embodiment, this invention is not limited to the above-mentioned example, Various modifications are possible in the range which does not deviate from the summary of this invention.
FIG. 4 is a schematic configuration diagram showing a second embodiment of the metal filling apparatus of the present invention, and FIG. 5 is a schematic configuration diagram showing a third embodiment of the metal filling apparatus of the present invention. 4 and 5 are both cross-sectional views when the metal filling device is viewed from the front.
4 and 5, the configurations denoted by the same reference numerals as in FIGS. 1 to 3 are configured so that the metal filling devices 10 </ b> B and 10 </ b> C according to the second embodiment or the third embodiment are the metal filling devices 10 </ b> A according to the first embodiment. A portion having the same or similar configuration is shown, and redundant description may be omitted.

A metal filling device 10B according to the second embodiment has a metal surface purification mechanism 30 including a dirt removing member 31 that moves along the surface 7 of the molten metal 6 instead of the metal surface purification mechanism 20 shown in FIGS. Is provided. In the case of this example, the dirt removing member 31 is a squeegee that is reciprocated in both the left and right directions along a guide rail 32 provided above the molten metal tank 16a.
The dirt 8 generated on the surface 7 of the molten metal 6 is pushed and removed by the dirt removing member 31 to the outside of the molten metal tank 16a. When the substrate 2 is immersed in the molten metal tank 16a, the movement of the dirt removing member 31 is stopped so that the dirt removing member 31 does not hit the substrate 2 or the conveying jig 17.

Thus, by using the metal surface purification mechanism 30 having the dirt removing member 31 that moves along the surface 7 of the molten metal 6, dirt 8 such as metal oxide generated on the surface 7 of the molten metal 6 is removed. The surface 7 of the molten metal 6 at the location where the substrate 2 is immersed and pulled up can always be kept clean. Therefore, it is possible to prevent the dirt 8 from adhering to the substrate 2 and improve the yield and quality in the molten metal filling method.
Further, among the elements constituting the metal surface purification mechanism 30, only the dirt removing member 31 can be immersed in the molten metal 6, so that the heat resistance of the molten metal 6 against heat and contamination of the molten metal 6 can be achieved. It is easy to meet demands such as prevention and can be installed at low cost.
The movement of the dirt removing member 31 is not limited to a linear reciprocating motion, and may be a reciprocating motion along an arc or a rotational motion along a circumferential direction. The dirt removing member 31 is not limited to one, and a plurality of dirt removing members 31 may be provided.

In the metal filling apparatus 10C of the third embodiment, the partition plate 12 that partitions the chamber 11 into two rooms 11a and 11b is installed in the vertical direction as shown in FIG. 5 instead of in the horizontal direction as shown in FIG. Yes.
In the case of the metal filling apparatus 10C of this example, there are a first chamber 11a that can be opened by an on-off valve 13A for transporting the substrate 2 inside and outside the chamber 11, and a second chamber 11b that includes a metal melting device 16. An opening / closing valve 13 is provided on the partition plate 12 that is arranged in the horizontal direction and partitions the first chamber 11a and the second chamber 11b, and the substrate 2 is conveyed through these opening / closing valves 13, 13A. A conveying device 18 is installed in the horizontal direction. The conveyance device 18 can be constituted by a conveyance arm, a conveyance belt, or the like.
In the upper part of the second chamber 11b, the substrate 2 (see FIG. 3 for details) in which the fine holes 4 are formed is held, and the substrate 2 is located outside the molten metal 6 of the metal melting device 16 and melted. A conveying jig 17 is provided so as to be able to freely reciprocate between the state immersed in the metal 6.

  In the metal filling device in which the two chambers 11a and 11b are arranged in the horizontal direction, FIG. 5 illustrates an example in which the metal surface purification mechanism 20 (see FIG. 1) having the jet pump 21 is provided. The configuration of the metal surface purification mechanism is not particularly limited. In addition to this, it is also possible to provide a metal surface purification mechanism having another configuration such as a metal surface purification mechanism 30 having a dirt removing member 31 (see FIG. 4).

A method for filling the metal 5 into the micropores 4 of the substrate 2 using the metal filling apparatus 10C of the third embodiment is as follows.
The second chamber 11b is evacuated by the decompression means 14b connected to the second chamber 11b and kept in a decompressed state in advance.
With the open / close valve 13 separating the first chamber 11a and the second chamber 11b closed, the open / close valve 13A communicating from the first chamber 11a to the outside is opened, and the substrate 2 is mounted on the conveyance assisting jig 18a. Installed in the first room 11a. Next, the on-off valve 13A is closed, and the first chamber 11a is decompressed to a pressure similar to that of the second chamber 11b by using the decompression means 14a connected to the first chamber 11a, and then opened and closed. Open the valve 13.
Thus, the second chamber 11b can be prevented from being completely exposed to the atmosphere by closing the opening / closing valve 13 when the first chamber 11a is opened to the atmosphere outside the chamber 11, so that the inside of the metal melting apparatus 16 It is possible to prevent significant oxidation of the molten metal 6 and mixing of large foreign matters into the molten metal 6.

Further, by driving the transfer device 18, the transfer auxiliary jig 18 a holding the substrate 2 is moved to the second chamber 11 b through the open / close valve 13 that is open.
In a state where the first chamber 11a and the second chamber 11b are depressurized to a first pressure lower than the atmospheric pressure, the transfer assist treatment in which the substrate 2 is held by the transfer jig 17 in the second chamber 11b. The tool 18a is picked up from the transfer device 18, the transfer jig 17 is lowered, and the substrate 2 is immersed in the molten metal 6 in the molten metal tank 16a (see FIG. 2).
Next, nitrogen gas is supplied into the chamber 11 by the pressurizing means 15a and 15b, and the pressure inside the first chamber 11a and the second chamber 11b is increased to a second pressure higher than the first pressure. The metal 5 which has been raised and melted is filled into the micro holes 4 with a differential pressure.

Next, the conveying jig 17 is raised, and the substrate 2 is pulled out of the molten metal 6 and cooled as shown in FIG. Thereby, the metal 5 filled in the fine holes 4 is solidified, and the substrate 1 in which the fine holes 4 are filled with the metal 5 is obtained.
The transfer auxiliary jig 18a holding the substrate 2 is removed from the transfer jig 17 and moved to the transfer device 18, and after the transfer auxiliary jig 18a is moved to the first chamber 11a side, the opening / closing valve 13 of the partition plate 12 is closed. After evacuating the inside of the second chamber 11b, the first chamber 11a is opened, and the substrate 2 is removed from the conveyance auxiliary jig 18a.

  The metal filling device of the present invention is not limited to the configuration in which the chamber 11 is divided by the partition plate 12, but the first chamber 11a and the second chamber 11b are configured by independent chambers. It is also possible to have a configuration in which the chambers are arranged in the horizontal direction or overlapped in the vertical direction, and a passage is formed between the chambers. Even in this case, the same excellent effects as those of the metal filling apparatus described above can be obtained.

  The metal filling apparatus of the present invention preferably includes at least one mechanism for heating the substrate (hereinafter referred to as a substrate heating mechanism) in the chamber. Here, the substrate heating mechanism is capable of heating the substrate before immersing the substrate in the molten metal. Within this limit, the position where the substrate heating mechanism is installed is appropriately within the chamber. Setting is possible. The structure of the chamber in the case of providing the substrate heating mechanism is not particularly limited. For example, when the inside of the chamber is divided into two or more rooms, the substrate heating mechanism may be any one or two or more rooms of the chamber. If the chamber is configured by connecting two or more chambers, the substrate heating mechanism can be provided in any one or two or more chambers.

  As the substrate heating mechanism, an infrared lamp, a hot plate, and the like are exemplified as those capable of heating the substrate in the atmospheric gas in the chamber, but are not particularly limited thereto. Two or more substrate heating mechanisms or two or more types may be provided in the chamber. Specific examples of the substrate heating mechanism include an infrared lamp 41 capable of heating the substrate 2 held by the transfer jig 17 as shown in FIG. 6, and a substrate placed on the upper surface as shown in FIG. The hot plate 42 which can heat 2 is mentioned. 6 and 7, the illustration of the metal melting device and the metal surface purification mechanism is omitted. However, as in the examples shown in FIGS. Can be provided in the second room 11b of the two rooms 11a and 11b.

  As yet another example, FIG. 6 shows a case where an infrared lamp 41 is provided in the first room 11a of the chamber 11 divided into the upper and lower two rooms 11a and 11b by the partition plate 12. Instead of this, an infrared lamp may be provided in the second room 11b, or an infrared lamp may be provided in both the rooms 11a and 11b. Moreover, as shown in FIG. 5, in the chamber 11 in which the two rooms 11a and 11b are arranged in the horizontal direction, a configuration in which an infrared lamp is provided in one or both of the rooms can be implemented.

  The method for filling metal into the micropores formed in the substrate using the metal filling apparatus provided with the substrate heating mechanism is the same as the method described above with reference to FIG. it can. That is, a step of heating the substrate before immersion in molten metal using the substrate heating mechanism, and the surface of the heated substrate is cleaned by the metal surface purification mechanism under a first pressure lower than atmospheric pressure. A step of immersing in the retained molten metal, a step of increasing the first pressure to a second pressure higher than the first pressure and filling the molten metal with a differential pressure, and a step of filling the substrate with the molten metal. By using a metal filling method having a step of pulling up from the metal, good metal filling can be performed.

By heating the substrate before immersion in the molten metal using the substrate heating mechanism, the temperature drop of the metal due to the temperature difference during immersion of the substrate and the accompanying filling defects are reduced as compared with the case where the substrate is not heated. be able to. The temperature of the substrate after heating by the substrate heating mechanism is preferably as the temperature difference from the molten metal is smaller, and is most preferably equal to the temperature of the molten metal when immersed in the molten metal. The heating temperature of the substrate can be set in consideration of the temperature change of the substrate until it is immersed in the substrate. Further, if necessary, a control means for controlling the heating temperature of the substrate by the substrate heating mechanism can be added.
In the present invention, after the substrate is placed in the chamber, the substrate is heated, and at least when immersed in the molten metal, the above effect can be obtained if the substrate is heated to a temperature higher than that of the substrate before heating. it can. The temperature of the substrate after heating may be higher than the temperature of the molten metal as long as the effect of the present invention is not impaired.

  Before dipping the substrate in the molten metal, the substrate is heated to the same temperature as the molten metal, greatly reducing the temperature drop of the metal due to the temperature difference during substrate immersion and the accompanying filling defects. Can do. In the present invention, “the substrate after heating is at the same temperature as the molten metal” means that the temperature of the molten metal around the substrate is not significantly lowered when the substrate is immersed as described above. The specific temperature difference (temperature difference between the heated substrate and the molten metal during immersion) depends on the nature of the substrate and the molten metal (heat capacity and specific heat), or the flow of the molten metal when given to the molten metal. It can vary depending on various implementation conditions, such as speed.

  The present invention can be used, for example, to fabricate wiring such as an electronic device or an optical device, a structure of a MEMS device, or the like.

It is a schematic block diagram which shows the 1st form example of the metal filling apparatus of this invention. It is explanatory drawing explaining the method to fill a metal in the micropore formed in the board | substrate using the metal filling apparatus shown in FIG. (A)-(d) It is a cross-sectional process drawing explaining the metal filling process of filling a metal in a micropore using a molten metal filling method. It is a schematic block diagram which shows the 2nd example of a metal filling apparatus of this invention. It is a schematic block diagram which shows the 3rd example of a metal filling apparatus of this invention. It is explanatory drawing which shows the 1st example of the mechanism which heats the board | substrate used for the metal filling apparatus of this invention. It is explanatory drawing which shows the 2nd example of the mechanism which heats the board | substrate used for the metal filling apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Board | substrate, 4 ... Fine hole, 5 ... Filled metal, 6 ... Heat-melted metal, 7 ... Surface of molten metal, 10A, 10B, 10C ... Metal filling apparatus, 11 ... Chamber, 11a, 11b ... Chamber Internal chambers, 14a, 14b ... decompression means (evacuation system), 15a, 15b ... pressurization means (gas supply system), 16 ... metal melting apparatus, 16a ... molten metal tank, 20 ... metal surface purification mechanism, DESCRIPTION OF SYMBOLS 21 ... Jet pump, 22 ... 2nd tank, 23 ... Upper edge of 2nd tank, 24 ... Intake port, 30 ... Metal surface purification mechanism, 31 ... Dirt removal member, 41 ... Infrared lamp (substrate heating mechanism), 42 ... Hot plate (substrate heating mechanism).

Claims (8)

A chamber provided with a decompression means for decompressing the inside and a pressurization means for pressurizing the interior, and a metal melting apparatus capable of heating and melting the metal in the chamber, and the metal is introduced into the micropores formed in the substrate In a metal filling device for filling,
The metal melting apparatus includes a metal surface purification mechanism that keeps the surface of the heat-melted metal clean.   The metal filling device according to claim 1, wherein the metal surface purification mechanism includes a jet pump that generates a flow along a surface of the heat-melted metal.   The metal surface purification mechanism includes a second tank provided inside a molten metal tank in which the metal melted by heating in the metal melting apparatus is stored, and an upper edge of the second tank is a second Projecting above the surface of the molten metal stored outside the tank, and the jet pump supplies the molten metal to the inside of the second tank through an intake opening opened at the bottom of the second tank. The metal filling device according to claim 2, wherein the metal filling device generates a flow to be taken in.   2. The metal according to claim 1, wherein the metal surface purification mechanism includes a dirt removing member that moves along the surface of the heated and melted metal to push and remove dirt on the surface of the molten metal. Filling equipment.   The metal filling device according to any one of claims 1 to 4, wherein the interior of the chamber is divided into two or more rooms, or two or more chambers are connected.   6. The metal filling apparatus according to claim 5, further comprising at least one mechanism for heating the substrate in at least one room of the chamber or in at least one chamber. A metal filling method using the metal filling device according to any one of claims 1 to 5 to fill a fine hole formed in a substrate with a metal,
Immersing the substrate in a molten metal whose surface is kept clean by the metal surface purification mechanism under a first pressure lower than atmospheric pressure;
Increasing the first pressure to a second pressure higher than this and filling the molten metal with a differential pressure;
And a step of pulling up the substrate from the molten metal.   The metal filling method according to claim 7, wherein the substrate is heated in advance to a temperature approximately equal to a temperature of the molten metal before the substrate is immersed in the molten metal.

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