JP4864591B2 - Soldering method and soldering apparatus - Google Patents

Description

  The present invention relates to a soldering method and a soldering apparatus, and in particular, for example, is formed on the first main surface in a state where the first main surface of the first substrate and the second main surface of the second substrate face each other. The present invention relates to a soldering method and a soldering apparatus for so-called flip chip connection, in which a first electrode and a second electrode formed on a second main surface are soldered.

  In flip-chip connection, prior to soldering, an oxide film covering the surface of a part to be soldered, for example, an electrode of each substrate and a solder bump electrode called a solder bump, may be removed. Therefore, it is important to make it reliable. As a technique for removing such an oxide film, there is a technique disclosed in Patent Document 1, for example.

  According to this prior art, a substrate such as a silicon wafer is placed in the chamber as an object to be processed. Then, solid solder that is the basis of the solder bump is disposed on the electrode pad of the substrate, and then the chamber is closed. Further, the inside of the chamber is evacuated to a high vacuum state by a vacuum pump, that is, evacuated. After this evacuation, the entire substrate including the solder is heated to a temperature lower than the melting point of the solder, and in this state, hydrogen radicals as free radical gas are generated in the chamber. Then, the hydrogen radicals react with the oxide film attached to the solder, whereby the oxide film is reduced and removed.

  After the oxide film is removed in this manner, the generation of hydrogen radicals is stopped and the chamber is evacuated again. Then, after this evacuation, nitrogen gas is supplied into the chamber, and the inside of the chamber is made non-oxidizing atmosphere. Furthermore, in this non-oxidizing atmosphere, the entire substrate is heated to a temperature higher than the melting point of the solder. As a result, the solder melts and solder bumps are formed on the electrode pads. After the formation of the solder bumps, the substrate is cooled to room temperature and the chamber is returned to atmospheric pressure.

  Furthermore, according to the prior art, it is disclosed that another substrate can be flip-chip connected to the substrate on which the solder bumps are formed as described above. That is, an electrode of another substrate is brought into contact with the electrode pad of the substrate on which the solder bump is formed, and the inside of the chamber is evacuated again in this state. After this evacuation, free radical gas is generated in the chamber at a temperature equal to or higher than the melting point of the solder to melt the solder bumps, thereby soldering each substrate, that is, flip-chip connection. It is disclosed that it is possible.

JP 2005-230830 A

  By the way, it is extremely difficult to perform an alignment operation of bringing an electrode of another substrate into contact with an electrode pad of a substrate on which a solder bump is formed as described above, for example, in a chamber. For this reason, the alignment operation is actually performed outside the chamber, that is, in the atmosphere. That is, the substrate on which the solder bumps are formed as described above is once taken out into the atmosphere. Then, the substrate is aligned with another substrate in the atmosphere, and returned to the chamber and flip chip connected while maintaining the aligned state.

  However, when the substrate after the solder bump is formed in this way is taken out into the atmosphere, naturally, the surface of the solder bump is oxidized and an oxide film is formed again. In this case, as described above, removing the oxide film at the time of forming the solder bumps is completely meaningless, and the reliability (quality) of the flip chip connection is lowered.

  Accordingly, an object of the present invention is to provide a soldering method and a soldering apparatus that can realize flip chip connection with higher reliability than conventional ones.

  In order to achieve such an object, the first invention is the first main surface formed on the first main surface with the first main surface of the first substrate and the second main surface of the second substrate facing each other. In a soldering method for soldering one electrode and a second electrode formed on a second main surface to each other, a first substrate installation step of installing a first substrate in a vacuum chamber, and a second substrate in the vacuum chamber And a second substrate installation step of installing. Specifically, in the first substrate installation step, the first substrate is installed in the vacuum chamber with the first main surface horizontal and the first main surface facing upward. Then, in the second substrate installation step, the second substrate has a second main surface that is horizontal so that the second electrode is positioned with a space immediately above the first electrode, and the second main surface is downward. It is installed in the vacuum chamber in the state of facing. That is, the second substrate is installed above the first substrate. Note that either the first substrate installation step or the second substrate installation step may be performed first, or both may be performed simultaneously. And after the 1st board | substrate and the 2nd board | substrate are installed in a vacuum chamber in this way, this invention continues an exhaust process, an oxide film removal process, an alignment process, and a joining process in this order. It is characterized by carrying out automatically.

  That is, first, in the exhaust process, the inside of the vacuum chamber is exhausted. Thereby, the inside of the vacuum chamber is set to a low oxygen atmosphere (in other words, a non-oxidizing atmosphere). Then, in the subsequent oxide film removing step, the reducing gas is introduced into the vacuum chamber in such a low oxygen atmosphere, thereby exposing the surfaces of the first electrode and the second electrode to the reducing gas. As a result, the oxide film formed on the surfaces of the first electrode and the second electrode and the reducing gas react with each other, and the oxide film is reduced and removed. In this oxide film removing step, the surface of the solder applied to at least one of the first electrode and the second electrode is also exposed to the reducing gas, so that the oxide film formed on the surface of the solder is the same. Removed. And even after the completion of this oxide film removal step, the low oxygen atmosphere state in the vacuum chamber is maintained, and the subsequent alignment step is performed. In the alignment step, the second substrate is lowered directly below. Thus, the first electrode and the second electrode are overlapped with each other via the solder, that is, the first substrate and the second substrate are aligned. And even after this alignment process, the low oxygen atmosphere state in a vacuum chamber is maintained, and the subsequent joining process is performed. In the connecting step, the solder interposed between the first electrode and the second electrode is melted. As a result, the first electrode and the second electrode are joined to each other via the solder, that is, flip chip connection is realized.

  Thus, according to the first invention, the oxide film removing step of removing the oxide film covering the surfaces of the first electrode and the second electrode to be soldered, and the first electrode and the second electrode are removed. An alignment step of aligning the electrodes by overlapping each other and a joining step of soldering the first electrode and the second electrode to each other are continuously performed in a low oxygen atmosphere.

  For example, hydrogen gas is suitable as the reducing gas used in the oxide film removal and removal step. Further, hydrogen plasma may be generated by converting hydrogen gas into plasma, and this hydrogen plasma may be used as the reducing gas. Furthermore, among hydrogen ions, electrons, and hydrogen radicals (free radicals) contained in hydrogen plasma, hydrogen ions and electrons that are charged particles are excluded, and only hydrogen radicals that are so-called neutral particles having no charge are reduced to a reducing gas. May be adopted. Since hydrogen radicals are chemically unstable, in other words, highly active, the oxide film can be effectively reduced and removed. In addition to hydrogen gas, an inert gas such as argon gas may be mixed, or an organic acid gas such as formic acid may be employed instead of the hydrogen gas.

  In addition, in the oxide film removal step, it is desirable that the reducing gas be actively (forcedly) circulated in the space between the first electrode and the second electrode to be processed. At this time, along the first main surface of the first substrate on which the first electrodes are formed and the second main surface of the second substrate on which the second electrodes are formed, that is, The reducing gas may be circulated along a direction substantially parallel to the first main surface and the second main surface. If it does in this way, reducing gas can be spread to every corner of the said 1st electrode and the 2nd electrode, and an oxide film can be removed more effectively by extension.

  Furthermore, in the oxide film removing step, the above-described hydrogen plasma is used as the reducing gas, whereby the processing temperature in the oxide film removing step can be suppressed. Specifically, the temperature is lower than the melting point of the solder. The oxide film removal step can be performed. In this case, in the second substrate installation step, the second substrate may be supported by a solid member having a melting point that is higher than the processing temperature in the oxide film removal step and lower than the melting point of the solder. In this way, in the subsequent alignment step, by melting the solid member, the support state of the second substrate by the solid member can be released, and the second substrate can be lowered directly below.

  Such a solid member can be formed of the same material as solder, for example. In this way, it is not necessary to prepare a special material (that is, different from the solder) in order to form the solid member, which is extremely beneficial from the viewpoints of economy and material management.

  The solid member can be provided so as to be interposed between the first main surface of the first substrate and the second main surface of the second substrate. In this case, the solid member may be integrated in advance with at least one of the first substrate (first main surface) and the second substrate (second main surface).

  Furthermore, a first dummy electrode different from the first electrode is provided on the first main surface of the first substrate, and a second main surface of the second substrate is arranged on the second main surface so as to face the first dummy electrode. A second dummy electrode different from the electrode may be provided, and a solid member may be interposed between the first dummy electrode and the second dummy electrode. In this way, when the solid member is melted in the alignment step, the first dummy electrode and the second dummy electrode are attracted to each other by the surface tension of the melted solid member. The alignment with the second substrate is performed more accurately.

  As the solder in the first invention, for example, there is a solder bump. That is, the solder bump may be formed in advance on at least one of the first electrode and the second electrode. Moreover, not only this but the spherical solder ball used as the origin of a solder bump may be attached | subjected to at least one of the 1st electrode and the 2nd electrode. In this case, it is desirable to fix the solder ball with a flux that does not generate a residue or an adhesive mainly composed of alcohol or organic acid. Further, instead of the solder balls, for example, a solid solder layer that can be formed by a plating process or a paste solder layer that can be formed by a printing process may be applied in advance as the solder.

  Next, according to a second aspect of the present invention, the first electrode and the second electrode formed on the first main surface in a state where the first main surface of the first substrate and the second main surface of the second substrate face each other. In a soldering apparatus for soldering the second electrodes formed on the main surface to each other, the vacuum chamber and the first main surface in the state where the first main surface is horizontal and the first main surface is directed upward in the vacuum chamber. A first substrate placing means on which the substrate is placed, and a second principal surface in the same vacuum chamber so that the second electrode is positioned with a space directly above the first electrode, and the second principal surface is Second substrate placement means for placing the second substrate in a state of facing downward. And the exhaust means which exhausts the inside of the vacuum chamber in which the 1st board | substrate and the 2nd board | substrate were installed in this way and makes the said inside of the said vacuum chamber a low oxygen atmosphere, and the inside of the vacuum tank made into the low oxygen atmosphere by this exhaust means And an oxide film removing means for removing the oxide film formed on the surfaces by exposing the surfaces of the first electrode and the second electrode to a reducing gas. Further, in the vacuum chamber in which the low oxygen atmosphere state is maintained following the oxide film removing process by the oxide film removing means, the second substrate is lowered directly below and the first electrode and the second electrode are overlapped with each other. And a joining means for joining the first electrode and the second electrode together by melting the solder in a vacuum chamber in which a low oxygen atmosphere state is maintained following the positioning by the positioning means. It is to be prepared.

  That is, the first invention described above relates to a soldering method, whereas the second invention relates to a soldering apparatus corresponding to the first invention. And according to the soldering apparatus of this 2nd invention, the soldering method of the 1st invention is realizable. That is, a step of removing the oxide film covering the surfaces of the first electrode and the second electrode to be soldered, a step of superposing and aligning the first electrode and the second electrode, The step of soldering the first electrode and the second electrode to each other can be performed continuously in a low oxygen atmosphere.

  In the second invention as well, as in the first invention, when the oxide film covering the surfaces of the first electrode and the second electrode is removed, the space between the first electrode and the second electrode is removed. It is desirable that the reducing gas is circulated actively, specifically, the reducing gas is circulated along a direction substantially parallel to the first main surface of the first substrate and the second main surface of the second substrate. That is, it is desirable to provide a gas distribution means for distributing the reducing gas in this way.

  Further, if the above-described hydrogen plasma is used as the reducing gas, the processing temperature when removing the oxide film can be suppressed, and specifically, the oxide film is removed at a temperature lower than the melting point of the solder. can do. In this case, the second substrate setting means includes a solid member having a melting point that is higher than the processing temperature for removing the oxide film and not higher than the melting point of the solder, and supports the second substrate by the solid member. It is good also as what to do. If it does in this way, the alignment means can cancel | release the support state of the 2nd board | substrate by the said solid member by melt | dissolving this solid member, and can descend | fall below a 2nd board | substrate.

  The solid member here can be formed of the same material as that of solder, for example, as in the first invention.

  Furthermore, a first dummy electrode different from the first electrode is provided on the first main surface of the first substrate, and a second main surface of the second substrate is arranged on the second main surface so as to face the first dummy electrode. A second dummy electrode different from the electrode may be provided, and a solid member may be interposed between the first dummy electrode and the second dummy electrode. In this way, when the solid member is melted by the alignment means, the first dummy electrode and the second dummy electrode are attracted to each other by the surface tension of the melted solid member, and as a result, the first substrate and The alignment with the second substrate is performed more accurately.

  As the solder, a solder bump, a solder ball, a solid solder layer that can be formed by a plating process, or a paste solder layer that can be formed by a printing process can be used.

  As described above, according to the present invention, the step of removing the oxide film covering the surfaces of the first electrode and the second electrode to be soldered and the first electrode and the second electrode are overlapped with each other. And aligning the first electrode and the second electrode with each other can be continuously performed in a low oxygen atmosphere. In other words, the first electrode and the second electrode are not exposed to the atmosphere until they are aligned and further soldered after being pretreated. Therefore, unlike the above-described conventional technique in which the substrate to be soldered is exposed to the atmosphere before soldering, the first electrode and the second electrode are not oxidized before soldering. Therefore, flip-chip connection with higher reliability than before can be realized.

  An embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, a soldering apparatus 10 according to this embodiment includes a box-shaped metal chamber 12 as a vacuum chamber. In the inside of the chamber 12, that is, in a vacuum chamber, a substantially flat heating stage 14 is disposed with its upper surface leveled, and the upper surface of the heating stage 14 is to be soldered. A plurality of workpieces 16, 16,... Are installed. That is, the heating stage 14 functions as an installation means for installing the workpieces 16, 16,... More specifically, the heating stage 14 is provided with an intermediate substrate (interposer) 100 as a first substrate to be described later. It functions as one substrate installation means.

  Further, the heating stage 14 also functions as a heating means for heating the workpieces 16, 16,. For this reason, the heating stage 14 is made of a material having a relatively small heat capacity, for example, ceramic or carbon. In addition, a resistance heater 18 is provided inside the heating stage 14, and the workpieces 16, 16,... Are heated by heat generated by the resistance heater 18. The heating temperature of the workpieces 16, 16,... By the resistance heater 18 is, for example, from room temperature to a temperature equal to or higher than the melting point of the solder 108 described later by a heater heating power supply device (not shown) provided outside the chamber 12. Specifically, it can be arbitrarily controlled in the range of 15 [° C.] to 400 [° C.].

  Although not shown in the drawing, in addition to the resistance heater 18, a water cooling type cooling device as a cooling means is attached to the heating stage 14. This cooling device is in a non-contact state with respect to the heating stage 14 when the above-described heater heating power is supplied to the resistance heater 18, that is, when energized. When the energization of the resistance heater 18 is cut off and the workpieces 16, 16,... Need to be cooled, the entire bottom surface of the heating stage 14 is brought into contact with the heating stage 14 and the workpiece 16. , 16... Are cooled. In this way, the cooling device is attached to the heating stage 14, thereby enabling more accurate and quick temperature control of the workpieces 16, 16,.

  Further, an exhaust port 20 is provided at an appropriate position of the wall portion of the chamber 12, for example, at a substantially central position of the bottom wall. The exhaust port 20 is connected to a vacuum pump 24 as an exhaust means provided outside the chamber 12 via an exhaust pipe 22. As the vacuum pump 24, for example, a combination of a mechanical booster pump and a rotary pump is employed. Of course, other pumps may be used. Although not shown in the drawing, in the middle of the exhaust pipe 22, there is provided a pressure control means, for example, a conductance valve, for controlling the amount of exhaust by the vacuum pump 24 and thus controlling the pressure in the chamber 12. Yes.

  Further, a metal shielding plate 26 is provided at a position closer to the upper side in the chamber 12 along the horizontal so as to bisect the inside of the chamber 12. The shielding plate 26 is formed, for example, by drilling a plurality of through holes penetrating from one main surface (upper surface) to the other main surface (lower surface) in an aluminum plate having a thickness of about 5 [mm]. . The diameter of these through holes is smaller than the thickness dimension of the shielding plate 26, in other words, the length dimension of the through hole, for example, about 1 [mm]. The distance between the through holes, that is, the pitch, is about several [mm] larger than the diameter of the through holes, and more specifically, about 5 [mm] to 10 [mm]. An upper space 28 partitioned by the shielding plate 26 is a plasma light emitting chamber for generating hydrogen plasma, which will be described later, and a lower space 30 is soldered to the workpieces 16, 16,. It is a processing chamber for performing such processing. In FIG. 1, the plasma emission chamber 28 is smaller than the processing chamber 30, but the sizes of the plasma emission chamber 28 and the processing chamber 30 vary depending on various situations (for example, the scale of the soldering apparatus 10). And the types of the objects to be processed 16, 16,. Although not shown in the drawing, the shielding plate 26 is connected to a ground potential as a reference potential together with the wall portion of the chamber 12.

The plasma emission chamber 28 is a space for generating hydrogen plasma as described above, and is provided outside the chamber 12 through the gas introduction pipe 32 in order to introduce hydrogen (H ₂ ) gas into the space. Coupled to a hydrogen gas source 34. Although not shown in the drawing, the hydrogen gas source 34 is a supply amount adjusting means for adjusting the supply amount (flow rate) of hydrogen gas supplied to the plasma light emitting chamber 28 via the gas introduction pipe 32, for example, mass flow. Controller.

  A quartz microwave introduction window 36 is provided on the upper wall of the chamber 12 constituting the upper wall of the plasma light emitting chamber 28 so as to occupy most of the area including the central portion thereof. Further, above the microwave introduction window 36, a waveguide 38 having the microwave introduction window 36 as an output end extends along the upper surface of the microwave introduction window 36, that is, along the horizontal direction. It is provided to do. A microwave generator 40 that generates a microwave having a frequency of 2.45 [GHz] is coupled to the input end of the waveguide 38.

  Thus, according to the plasma emission chamber 28 to which the gas introduction tube 32, the hydrogen gas source 34, the microwave introduction window 36, the waveguide 38 and the micro generator 40 are attached, hydrogen plasma is generated in the following procedure. . That is, first, the inside of the chamber 12 including the plasma light emitting chamber 28 is evacuated to a high vacuum state of about 1 [Pa] to 2 [Pa] by the vacuum pump 24, that is, evacuated. Then, after this evacuation, as indicated by an arrow 42 in FIG. 1, hydrogen gas is introduced from the hydrogen gas source 34 into the plasma emission chamber 28 through the gas introduction tube 32. At this time, the pressure in the chamber 12 including the plasma emission chamber is adjusted to about 10 [Pa] to 200 [Pa] by the conductance valve described above.

  At the same time, microwaves are introduced into the plasma emission chamber 28 from the microwave generator 40 through the waveguide 38 and the microwave introduction window 36 as indicated by an arrow 44 in FIG. Then, in response to the energy of the microwave, the hydrogen gas particles introduced into the plasma emission chamber 28 are discharged, thereby generating hydrogen plasma in the plasma emission chamber 28. Since the microwave easily propagates on the surface of quartz, the waveguide 38 is extended along the upper surface of the microwave introduction window 36 made of quartz. The microwaves can be efficiently diffused into the plasma light emission chamber 28 through the microwave introduction window 36, and as a result, a higher density hydrogen plasma can be generated.

The hydrogen plasma generated in the plasma emission chamber 28 in this manner contains hydrogen ions H ⁺ , electrons e ⁻ and hydrogen radicals (free radicals) H ^*. Among these, hydrogen ions H ⁺ and electrons e which are charged particles. ^- via the shield plate 26 flows to the ground potential, is so to speak eliminated. Then, only the hydrogen radicals H ^* that are neutral particles having no electric charge pass through the shielding plate 26 (through hole) by the exhaust action of the vacuum pump 24 and are guided to the processing chamber 30. That is, the shielding plate 26 functions as a kind of filter means for allowing only hydrogen radicals H ^* to pass therethrough.

In the processing chamber 30, there is provided a gas flow guide 48 as a gas flow means for flowing the hydrogen radicals H ^* that have passed through the shielding plate 26 through a route as shown by dotted arrows 46 and 46 in FIG. It has been. Specifically, the gas flow guide 48 is collected by the collecting unit 50 having a substantially funnel-like collecting unit 50 that collects the hydrogen radicals H ^* that have passed through the shielding plate 26 once in the vicinity of the center of the processing chamber 30. and a substantially tubular guiding portion 52 guided to the vicinity of the upper surface of the hydrogen radicals H ^* a heating stage 14, the outer the guiding portion 52 by the induced hydrogen radicals H ^* along the upper surface of the heating stage 14 (heating And a hollow flat plate-like diffusion portion 54 that diffuses in the direction from the center of the upper surface of the stage 14 toward the periphery. Then, in a state where the hydrogen radicals H ^* are guided by the gas flow guide 48 as described above, the processing objects 16, 16,... On the heating stage 14 are subjected to processing such as soldering in the following manner. .

  That is, according to the soldering apparatus 10 of this embodiment, a semiconductor device as shown in FIG. 2 can be manufactured as the object 16 to be processed. Strictly speaking, the intermediate substrate 100 as the first substrate described above and The semiconductor chip (bare chip) 102 as the second substrate can be soldered, that is, flip-chip connected.

  More specifically, the intermediate substrate 100 has a plurality of disk-shaped microelectrodes 104, 104,... As the first electrode on the upper surface as the first main surface. On the other hand, the semiconductor chip 102 has a plurality of disk-shaped microelectrodes 106, 106,... As second electrodes corresponding to the electrodes 104, 104,. is doing. The electrodes 104, 104, ... on the intermediate substrate 100 side and the electrodes 106, 106, ... on the semiconductor chip 102 side are joined via solders 108, 108, ..., that is, soldered. Further, prior to this soldering, the electrodes 104, 104,... And 106, 106,. Are processed to remove oxide films (not shown) formed on the surfaces of solder bumps 108, 108,.

  FIG. 3 shows the workpiece 12 before these processes are performed. As shown in FIG. 3, before processing, the intermediate substrate 100 and the semiconductor chip 102 are parallel to each other with a space 110 therebetween, and electrodes 104, 104,. ... they face each other straight (facing). Between the upper surface of the intermediate substrate 100 and the lower surface of the semiconductor chip 102, a plurality of solid members having the same specifications, for example, four columnar spacers 112, 112,. ing. In other words, the semiconductor chip 102 is supported by these four spacers 112, 112,... So that the space 110 is separated from the intermediate substrate 100.

  More specifically, the spacers 112, 112,... Are provided so as to connect the four corner positions on the upper surface of the intermediate substrate 100 and the four corner positions on the lower surface of the semiconductor chip 102. And each coupling | bond part is being fixed with the sticking agent which is not shown in figure. That is, before the processing, the intermediate substrate 100 and the semiconductor chip 102 are in an integrated state via the spacers 112, 112,. In addition, as a sticking agent said here, the flux which does not produce a residue, or the adhesive agent which has alcohol or an organic acid as a main component is employ | adopted, for example. In addition, the spacers 112, 112,... Are made of the same material (that is, solder) as the solders 108, 108,. Further, at the joint portion of each spacer 112, 112,... On the intermediate substrate 100 side, disk-shaped dummy electrodes (pad-only electrodes) 114, 114,. Is provided. Further, due to the provision of the dummy electrodes 114, 114,..., The outer peripheral dimension of the intermediate substrate 100 is slightly larger (about one turn) than the outer peripheral dimension of the semiconductor chip 102.

  Further, solder bumps that are the original shapes of the solders 108, 108,... Are formed on the electrodes 106, 106,. The solder bumps 108, 108,... Are made of, for example, an alloy of tin (Sn), silver (Ag), and copper (Cu), and have a melting point of about 220 [° C.]. As described above, the spacers 112, 112,... Are also made of the same material as the solder bumps 108, 108,..., That is, made of a tin-silver-copper alloy having a melting point of about 220 [° C.]. Yes.

The workpiece 16 before processing having such a configuration is on the heating stage 14 (not shown in FIG. 3) in the state shown in FIG. 3, that is, with the intermediate substrate 100 facing down and the semiconductor chip 102 facing up. Installed. As shown in FIG. 1, the chamber 12 is evacuated while a plurality of workpieces 16, 16,... Are installed on the heating stage 14. Further, after this evacuation, hydrogen plasma is generated in the plasma light emitting chamber 28 as described above, and hydrogen radicals H ^* contained in the hydrogen plasma are guided to the processing chamber 30, and as a result, each object to be processed on the heating stage 14. 16, 16,... Then, in the atmosphere of this hydrogen radical H ^* , as shown in FIG. 4, processing such as soldering is sequentially performed.

That is, first, as shown in FIG. 4A, a state in which hydrogen radicals H ^* circulate in the spaces 110 of the workpieces 16 along the upper surface of the intermediate substrate 100 and the lower surface of the semiconductor chip 102, in other words the electrodes 104, 104, ... and 106, 106, ..., and the solder bumps 108 and 108, with the ... surface (exposed surface) of which is exposed to the hydrogen radical ^{H *,} the object to be processed 16 The heating stage 14 (resistance heater 18) is heated to a temperature higher than normal temperature and lower than the melting point of the solder bumps 108, 108,. Then, each of the electrodes 104, 104, ... and 106, 106, ..., and the solder bumps 108, 108, ... oxide film (not shown) is formed on the surface of, mutually reacts with hydrogen radicals ^{H *,} thereby, the The oxide film is reduced and removed. The process for removing the oxide film, that is, the oxide film removing process is performed for about 1 minute.

  Subsequently, the heating stage 14 causes the workpiece 16 to have a temperature higher than the melting point of the solder bumps 108, 108,... And lower than the heat resistant temperature of the semiconductor chip 102, specifically, recommended soldering of the semiconductor chip 102. Heated at a temperature. Then, the solder bumps 108, 108,... Are melted, and the spacers 112, 112,... Formed of the same material as the solder bumps 108, 108,. Then, as the spacers 112, 112,... Melt, the support state of the semiconductor chip 102 by the spacers 112, 112,... Is released as shown in FIG. Descend. As a result, the electrodes 104, 104,... On the intermediate substrate 100 side and the electrodes 106, 106,... On the semiconductor chip 102 contact via the solder bumps 108, 108,. The melted spacers 112, 112,... Stay on the dummy electrodes 114, 114,... Provided below the spacers 112, 112,. There is no flow to the inner part. In other words, the dummy electrodes 114, 114,... Function as outflow prevention means for preventing the melted spacers 112, 112,.

  Then, after this alignment step, the semiconductor chip 102 is further pressed toward the intermediate substrate 100 by its own weight. As a result, as shown in FIG. 4C, the electrodes 104, 104,... On the intermediate substrate 100 side and the electrodes 106, 106,. Are joined, that is, soldered. And after this joining process, the to-be-processed object 16 is cooled to normal temperature with the heating stage 14 with the cooling device mentioned above. At the same time, the inside of the chamber 12 is returned to atmospheric pressure. Then, the workpiece 16 is taken out from the chamber 12, that is, the semiconductor device shown in FIG. 2 is completed.

That is, according to this embodiment, the oxide film removing process of FIG. 4A, the alignment process of FIG. 4B, and the bonding process of FIG. 4C are filled with hydrogen radicals H ^*. In a low oxygen atmosphere. In other words, the workpiece 16 is never exposed to the atmosphere until all of the oxide film removal process, the alignment process, and the bonding process are completed. Therefore, unlike the above-described conventional technique in which the substrate to be soldered is exposed to the atmosphere before soldering, the workpiece 16, particularly the electrodes 104, 104,..., 106, 106,. The bumps 108, 108,... Are not oxidized before the soldering (joining process). Therefore, flip-chip connection with higher reliability than before can be realized.

  Further, in the oxide film removal step and the alignment step, the workpieces 16, 16,... Are heated to some extent, so that so-called main heating in the joining step is performed smoothly. In other words, in the oxide film removing step and the alignment step, there is also an effect that the preliminary heating of preliminarily heating the workpieces 16, 16,.

Further, in the oxide film removal step, the gas flow guide 48 described above causes the hydrogen radical H ^* to actively circulate in the narrow space 110 sandwiched between the upper surface of the intermediate substrate 100 and the lower surface of the semiconductor chip 102. Since the hydrogen radical H ^* is guided, the removal process of the oxide film is efficiently and reliably performed. Further, by using this hydrogen radical H ^* , the flux as an oxide film removing agent that has been used so far becomes unnecessary, so that it is troublesome to apply this flux or remove the residue of the flux. Saves productivity. In addition, since an organic solvent for removing the flux residue is unnecessary, the influence on the environment is also suppressed.

  Further, according to this embodiment, the oxide film removing step is performed with the semiconductor chip 102 placed directly over the intermediate substrate 100 via the spacers 112, 112,... By melting 112, 112,..., The alignment of the intermediate substrate 100 and the semiconductor chip 102 is realized. That is, it is possible to achieve alignment in the vacuum chamber 12 that has been difficult until now, while adopting extremely simple and inexpensive solid members such as the spacers 112, 112,.

  In this embodiment, the spacers 112, 112,... Are made of the same material as the solder bumps 108, 108,. That is, the spacers 112, 112,... Have a temperature higher than the heating temperature of the workpiece 16 in the oxide film removal step shown in FIG. What is necessary is just to be formed with the material used as melting | fusing point. However, if the spacers 112, 112,... Are formed of the same material as the solder bumps 108, 108,..., As in this embodiment, a special (that is, solder) is used to form the spacers 112, 112,. There is no need to prepare another material, which is extremely beneficial from the viewpoints of economy and material management.

  Further, as shown in FIGS. 4B and 4C, the melted spacers 112, 112,... Remain on the dummy electrodes 114, 114,. , 112,... Need not be attached to portions other than the dummy electrodes 114, 114,. In other words, it is important to appropriately determine the sizes of the spacers 112, 112,... And the dummy electrodes 114, 114,.

  Further, in order to ensure the function as the outflow prevention means by the dummy electrodes 114, 114,..., The individual dummy electrodes 114 may be surrounded by a cylindrical wall 120 as shown in FIG. . In this case, the outflow prevention means may be realized only by the wall 120 without providing the dummy electrodes 114, 114,.

  Further, instead of the dummy electrodes 114, 114,..., For example, a concave recess 130 as shown in FIG. 6 is provided, and the melted spacer 112 is accommodated in the recess 130, thereby realizing the outflow prevention means. Good. Further, the metal film 132 may be formed inside the recess 130 in order to make the function as the outflow prevention means by the recess 130 more reliable.

In addition, in this embodiment, the spacers 112, 112,... Are cylindrical, but other shapes such as a prismatic shape or a wall shape may be used. Also, the number of the spacers 112, 112,... Is not limited to four, but may be other numbers. However, in the above-described oxide film removing step, it is important to set the shape and number of the spacers 112, 112,... So that the hydrogen radicals H ^* can efficiently flow through the space 110.

  Further, as the solder bumps (solders) 108, 108,..., Those made of a tin-silver-copper alloy having a melting point of about 220 [° C.] are used, but other solder bumps (solders) may be used. For example, a tin alloy containing one or more of lead (Pb), bismuth (Bi), indium (In), and zinc (Zn) may be employed as the solder bumps 108, 108,. . However, it is desirable to refrain from adopting lead from the viewpoint of so-called lead-free. Further, when the material of the solder bumps 108, 108,... Changes, the melting point thereof changes accordingly. Therefore, it is desirable to set the heating temperature of the workpiece 16 in each process according to the melting point.

  In this embodiment, the case where the solder bumps 108, 108,... Are formed in advance on the electrodes 106, 106,... On the semiconductor chip 102 side is described. For example, as shown in FIG. 7, the solder bumps 108, 108,... May be formed on the electrodes 104, 104,. Further, solder bumps 108, 108,... May be formed on both the electrodes 104, 104,... On the intermediate substrate 100 side and the electrodes 106, 106,.

  Further, not only the solder bumps 108, 108,..., But also, for example, as shown in FIG. 8, the solder balls that form the solder bumps 108, 108,. .. May be attached to at least one of the electrodes 106, 106,... On the chip 102 side, practically, the electrodes 104, 104,. In this case, in order to stabilize the solder balls 108, 108,... On the electrodes 104, 104,..., It is desirable to fix the solder balls 108, 108,. Further, instead of the adhesive, for example, recesses (not shown) are formed in the electrodes 104, 104,... And the solder balls 108, 108,. May be. When the solder balls 108, 108,... Are employed in this way, the solder balls 108, 108,... Are melted together with the spacers 112, 112,. As a result, solder bumps 108, 108,... Are formed on the electrodes 104, 104,.

  In addition to the solder balls 108, 108,... As shown in FIG. 8, a solid solder layer that can be formed by a generally known plating process, or a paste solder layer that can be formed by a printing process, It may be adopted. When these solder layers are employed, the solder layers are attached to the electrodes 106, 106,... On the upper side of the semiconductor chip 102, unlike the case where the solder balls 108,. You can also

  Further, as shown in FIG. 9A, dummy electrodes 116, 116,... May be provided not only on the intermediate substrate 100 side but also on the semiconductor chip 112 side at the junctions with the spacers 112, 112,. Good. That is, the dummy electrodes 116, 116,... Are provided at the four corner positions on the lower surface on the semiconductor chip 112 side corresponding to the positions where the dummy electrodes 114, 114,. ... may be provided. In this manner, in the alignment step shown in FIG. 9B, the first dummy electrodes 114, 114,... On the intermediate substrate 100 side and the second dummy electrodes 116, 116,. ... Are attached to both the spacers 112, 112,. Are attracted to each other by the surface tension of the melted spacers 112, 112,..., And as a result, the alignment accuracy is improved. Further, not only the electrodes 104, 104,... And 106, 106,... But also the dummy electrodes 114, 114,. Therefore, the bonding force between the intermediate substrate 100 and the semiconductor chip 102 is improved, and consequently the mechanical strength of the entire semiconductor device 16 as a finished product is improved.

  Furthermore, instead of the spacers 112, 112,..., For example, shape memory alloys 118, 118,... As shown in FIG. That is, the shape memory alloys 118, 118,... Have the same specifications as each other, and in the oxide film removal process of FIG. 10A, like the spacers 112, 112,. In other words, the semiconductor chip 102 is interposed between the substrate 100 and the semiconductor chip 102 to support the semiconductor chip 102. In the subsequent alignment step after the oxide film removal step, these shape memory alloys 118, 118,... Are heated to a higher temperature than in the oxide film removal step. Accordingly, as shown in FIG. 10B, each shape memory alloy 118, 118,... Is in a second state that is curved (or refracted) outward. Strictly speaking, this second state is the original state of the shape memory alloys 118, 118,..., And the first state is a state that is forcibly deformed by an external force. Then, the shape memory alloys 118, 118,... Are in the second state (that is, returned), so that the semiconductor chip 102 is lowered directly, and as a result, the semiconductor chip 102 and the intermediate substrate 100 are separated from each other. Alignment is realized. At the same time, the shape memory alloys 118, 118,... In the second state fall outward as indicated by arrows 119, 119,. Accordingly, in the subsequent joining step of FIG. 10C, the shape memory alloys 118, 118,... Are completely eliminated. Therefore, the shape memory alloys 118, 118,... Do not cause inconveniences such as a circuit short circuit in the completed semiconductor device 16. Further, the excluded shape memory alloys 118, 118,... Are reused in the next lot and subsequent times. Note that the shape memory alloys 118, 118,... In the first state are not limited to a cylindrical shape, but may have other shapes such as a prismatic shape or a plate shape.

  Further, for example, an elevating device 140 as shown in FIG. 11 may be employed as the second substrate installation means. That is, the elevating device 140 includes a holding unit 142 that holds both ends of the semiconductor chip 102 and an elevating unit 144 that moves the holding unit 142 in the vertical direction. Although not shown in the drawing, the elevating part 144 is coupled to the diffusion part 54 of the gas flow guide 48 described above.

  According to the configuration employing the lifting device 140, first, the semiconductor chip 102 is supported by the lifting device 140 in the oxide film removing step shown in FIG. 11B, as indicated by an arrow 146, the semiconductor chip 102 is lowered directly by the lifting device 140 (lifting portion 144), and then the lifting device 140 (holding portion 142). The holding state of the semiconductor chip 102 is released. Thereby, the alignment of the intermediate substrate 100 and the semiconductor chip 102 is performed. In the alignment process when the lifting device 140 is employed, the heating temperature of the workpiece 16 by the heating stage 14 is set to the same temperature as that in the oxide film removing process, that is, the solder bumps 108, 108,. It is not yet melted. Then, after this positioning step, the heating temperature by the heating stage 14 is raised to the recommended soldering temperature of the semiconductor chip 102 described above, and a joining step is performed as shown in FIG.

  And when employ | adopting the raising / lowering apparatus 140 in this way, as shown, for example in FIG. 12, you may install the intermediate substrate 100 and the semiconductor chip 102 upside down. That is, the semiconductor chip 102 may be directed downward, the intermediate substrate 100 may be directed upward, and the intermediate substrate 100 positioned above the semiconductor substrate 102 may be supported by the lifting device 104.

  In addition, also when adopting the above-described spacers 112, 112,... And shape memory alloys 118, 118,..., The semiconductor chip 102 can be down and the intermediate substrate 100 can be up. Since the upper surface of 102, that is, the circuit surface is in direct contact with the upper surface of the heating stage 14, it is not preferable for the circuit surface that is mechanically delicate. Therefore, when the spacers 112, 112,... Or the shape memory alloys 118, 118,... Are employed, it is desirable that the intermediate substrate 100 be down and the semiconductor chip 102 be up as described above.

Furthermore, the soldering apparatus 10 is not limited to the configuration shown in FIG. 1 described above, and may be configured as shown in FIG. 13, for example. That is, a shielding plate 26 is provided along the vertical so as to divide the inside of the chamber 12 in the horizontal direction, and the plasma emission chamber 28 partitioned by the shielding plate 26 is microscopically viewed from the side (left side in FIG. 13). The microwave introduction window 36, the waveguide 38, and the micro generator 40 are configured so that waves are introduced. In the processing chamber 30, similarly to the configuration shown in FIG. 1, the heating stage 14 is arranged so that the upper surface thereof is horizontal, and the workpieces 16, 16,. Install. Further, an exhaust port 20 is provided so as to face the shielding plate 26 across the heating stage 14. Thus, as indicated by the arrow 46 in FIG. 13, it becomes easy to form the hydrogen radicals H ^* in the distribution channel of circulating hydrogen radicals H ^* along the upper surface of the heating stage 14, i.e. the gas flow guide The structure of 48 can be simplified. Specifically, the gas flow guide 48 collects the hydrogen radicals H ^* that have passed through the shielding plate 26 in the vicinity of the upper surface of the heating stage 14, and the hydrogen radicals H ^* collected by the collection unit 50a ^. Can be constituted only by the diffusion part 54a that diffuses the liquid crystal along the upper surface of the heating stage 14. In addition, since the structure of the gas flow guide 48 can be simplified in this way, according to the configuration of FIG. 13 employing such a simple gas flow guide 48, the soldering device 10 is compared with the configuration of FIG. The whole can be reduced in size. Of course, the present invention is not limited to these FIG. 1 and FIG.

  Furthermore, in this embodiment, the microwave is used to generate the hydrogen plasma. However, for example, a high frequency having a frequency of 13.56 [MHz] may be used.

  In addition, although the resistance heater 18 is used to heat the workpieces 16, 16,..., Another means such as a heat radiator may be used instead. In addition, the cooling device described above may be omitted if it is not necessary.

In the above oxide film removing step, the oxide film is reduced and removed only by hydrogen radicals H ^* which are neutral particles. However, the present invention is not limited to this. That is, the oxide film may be reduced and removed not only by the hydrogen radical H ^* but also by hydrogen plasma containing hydrogen ions H ⁺ and electrons e ⁻ that are charged particles. In addition to hydrogen gas, an inert gas such as argon gas may be mixed, or an organic acid gas such as formic acid may be employed instead of the hydrogen gas.

Further, in the above alignment process and bonding process, for example, nitrogen gas is introduced into the chamber 12 without generating hydrogen plasma (hydrogen radical H ⁺ ), and the alignment process and bonding are performed in this nitrogen gas atmosphere. You may perform a process.

  Further, in this embodiment, the case where the intermediate substrate 100 and the semiconductor chip 102 are soldered (flip chip connection) has been described. Of course, the present invention is also applied to the case where other things are soldered. Can do.

  As described above, the content described in this embodiment is an example for realizing the present invention until it is tired, and does not limit the present invention.

It is a figure showing a schematic structure of a soldering device concerning one embodiment of this invention. It is a center longitudinal end view which shows schematic structure of the to-be-processed object in the same embodiment. It is a figure which shows schematic structure before the process of the to-be-processed object. It is an illustration figure which shows the process process of the to-be-processed object. It is a partially expanded sectional view which shows another example of the to-be-processed object. It is a partially expanded sectional view which shows another example from FIG. It is a center longitudinal cross-sectional view which shows another example from FIG. It is a center longitudinal cross-sectional view which shows another example from FIG. It is an illustration figure which shows another example from FIG. It is an illustration figure which shows the process process by a system different from FIG. It is an illustration figure which shows the process process by another system different from FIG. It is a center longitudinal cross-sectional view which shows another example of FIG. It is a figure which shows the example of a structure different from FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Soldering apparatus 12 Chamber 14 Heating stage 16 To-be-processed object 18 Resistance heater 24 Vacuum pump 34 Hydrogen gas source 100 Intermediate board 102 Semiconductor chip 104,106 Electrode 108 Solder (solder bump)
110 Space 112 Spacer

Claims (10)

The first electrode formed on the first main surface and the second main surface formed on the second main surface with the first main surface of the first substrate and the second main surface of the second substrate facing each other. In a soldering method for joining the first electrode and the second electrode to each other by solder applied to at least one of the two electrodes,
A first substrate installation step of installing the first substrate in a vacuum chamber with the first main surface horizontal and the first main surface facing upward;
The second substrate is placed in the vacuum chamber in a state where the second main surface is horizontal and the second main surface faces downward so that the second electrode is positioned with a space immediately above the first electrode. A second substrate installation process to be installed inside;
An evacuation step of evacuating the vacuum chamber in which the first substrate and the second substrate are installed to form a low oxygen atmosphere in the vacuum chamber;
An oxide film removing step of removing the oxide film formed on the surfaces of the first electrode and the second electrode by exposing the surfaces of the first electrode and the second electrode to a reducing gas in the vacuum chamber in the low oxygen atmosphere;
Positioning in which the first electrode and the second electrode are overlapped with each other by lowering the second substrate directly in the vacuum chamber in which the low oxygen atmosphere is maintained following the oxide film removing step. Process,
A joining step of joining the first electrode and the second electrode together by melting the solder in the vacuum chamber in which the state of the low oxygen atmosphere is maintained following the alignment step;
Equipped with,
The processing temperature in the oxide film removal step is lower than the melting point of the solder,
The second substrate is supported by a solid member formed of the same material as the solder in the second substrate installation step,
Releasing the support state of the second substrate by the solid member by melting the solid member in the alignment step and lowering the second substrate directly below;
A soldering method characterized by the above.   The reducing gas is circulated in the space between the first electrode and the second electrode in the oxide film removing step along a direction substantially parallel to the first main surface and the second main surface. The soldering method according to 1. Between the first dummy electrode formed on the first main surface and the second dummy electrode formed on the second main surface so as to face the first dummy electrode in the second substrate installation step. Supporting the second substrate by interposing the solid member;
The first dummy electrode and the second dummy electrode are attracted to each other by the surface tension of the solid member melted in the alignment step;
The soldering method according to claim 1 or 2 . The solder is a solder bump, solder balls, a solder layer formed by the solder layer or a printing process which is formed by plating, soldering method according to any one of claims 1 to 3. The first electrode formed on the first main surface and the second main surface formed on the second main surface with the first main surface of the first substrate and the second main surface of the second substrate facing each other. In a soldering apparatus for joining the first electrode and the second electrode to each other by solder applied to at least one of the two electrodes,
A vacuum chamber;
First substrate placement means for placing the first substrate in a state where the first principal surface is horizontal and the first principal surface faces upward in the vacuum chamber;
In the vacuum chamber, the second main surface is horizontal and the second main surface faces downward so that the second electrode is positioned with a space directly above the first electrode. A second substrate placement means on which the substrate is placed;
Exhaust means for evacuating the inside of the vacuum chamber in which the first substrate and the second substrate are installed to make the inside of the vacuum chamber a low oxygen atmosphere;
An oxide film removing means for removing an oxide film formed on the surfaces of the first electrode and the second electrode by exposing the surfaces of the first electrode and the second electrode to a reducing gas in the vacuum chamber in the low oxygen atmosphere;
Following the oxide film removal process by the oxide film removing means, the first electrode and the second electrode are lowered by lowering the second substrate directly in the vacuum chamber in which the state of the low oxygen atmosphere is maintained. Alignment means for overlapping each other;
A joining means for joining the first electrode and the second electrode together by melting the solder in the vacuum chamber in which the state of the low oxygen atmosphere is maintained following the positioning by the positioning means;
Equipped with,
The treatment temperature in the oxide film removal treatment is lower than the melting point of the solder,
The second substrate installation means includes a solid member provided to support the second substrate and formed of the same material as the solder,
The positioning means releases the support state of the second substrate by the solid member by melting the solid member and lowers the second substrate directly below;
Soldering device characterized by Gas flow means for flowing the reducing gas in the space between the first electrode and the second electrode in the oxide film removal process along a direction substantially parallel to the first main surface and the second main surface. The soldering apparatus according to claim 5 , further comprising: A first dummy electrode different from the first electrode is formed on the first main surface,
A second dummy electrode different from the second electrode is formed on the second main surface so as to face the first dummy electrode,
The solid member before being melted supports the second substrate by being interposed between the first dummy electrode and the second dummy electrode,
The solid member melted by the positioning means brings the first dummy electrode and the second dummy electrode together by surface tension;
The soldering apparatus according to claim 5 or 6 . The solder is a solder bump, solder balls, a solder layer formed by the solder layer or a printing process which is formed by plating, soldering apparatus according to any one of claims 5 to 7. The first electrode formed on the first main surface and the second main surface formed on the second main surface with the first main surface of the first substrate and the second main surface of the second substrate facing each other. In a soldering method for joining the first electrode and the second electrode to each other by solder applied to at least one of the two electrodes,
A first substrate installation step of installing the first substrate in a vacuum chamber with the first main surface horizontal and the first main surface facing upward;
The second substrate is placed in the vacuum chamber in a state where the second main surface is horizontal and the second main surface faces downward so that the second electrode is positioned with a space immediately above the first electrode. A second substrate installation process to be installed inside;
An evacuation step of evacuating the vacuum chamber in which the first substrate and the second substrate are installed to form a low oxygen atmosphere in the vacuum chamber;
An oxide film removing step of removing the oxide film formed on the surfaces of the first electrode and the second electrode by exposing the surfaces of the first electrode and the second electrode to a reducing gas in the vacuum chamber in the low oxygen atmosphere;
Positioning in which the first electrode and the second electrode are overlapped with each other by lowering the second substrate directly in the vacuum chamber in which the low oxygen atmosphere is maintained following the oxide film removing step. Process,
A joining step of joining the first electrode and the second electrode together by melting the solder in the vacuum chamber in which the state of the low oxygen atmosphere is maintained following the alignment step;
Comprising
Supporting the second substrate by interposing a shape memory alloy between the first substrate and the second substrate in the second substrate installation step;
The shape memory alloy is deformed to maintain the state of supporting the second substrate at a temperature equal to or lower than the processing temperature in the oxide film removing step and to release the supporting state of the second substrate at a temperature higher than the processing temperature. And
In the alignment step, the shape memory alloy is heated to a temperature higher than the processing temperature in the oxide film removal step, thereby releasing the support state of the second substrate by the shape memory alloy and lowering the second substrate directly below. Letting
A soldering method characterized by the above. The first electrode formed on the first main surface and the second main surface formed on the second main surface with the first main surface of the first substrate and the second main surface of the second substrate facing each other. In a soldering apparatus for joining the first electrode and the second electrode to each other by solder applied to at least one of the two electrodes,
A vacuum chamber;
First substrate placement means for placing the first substrate in a state where the first principal surface is horizontal and the first principal surface faces upward in the vacuum chamber;
In the vacuum chamber, the second main surface is horizontal and the second main surface faces downward so that the second electrode is positioned with a space directly above the first electrode. A second substrate placement means on which the substrate is placed;
Exhaust means for evacuating the inside of the vacuum chamber in which the first substrate and the second substrate are installed to make the inside of the vacuum chamber a low oxygen atmosphere;
An oxide film removing means for removing an oxide film formed on the surfaces of the first electrode and the second electrode by exposing the surfaces of the first electrode and the second electrode to a reducing gas in the vacuum chamber in the low oxygen atmosphere;
Following the oxide film removal process by the oxide film removing means, the first electrode and the second electrode are lowered by lowering the second substrate directly in the vacuum chamber in which the state of the low oxygen atmosphere is maintained. Alignment means for overlapping each other;
A joining means for joining the first electrode and the second electrode together by melting the solder in the vacuum chamber in which the state of the low oxygen atmosphere is maintained following the positioning by the positioning means;
Comprising
The second substrate installation means includes a shape memory alloy that is interposed between the first substrate and the second substrate and supports the second substrate,
The shape memory alloy is deformed to maintain the state of supporting the second substrate at a temperature equal to or lower than the processing temperature in the oxide film removal process and to release the supporting state of the second substrate at a temperature higher than the processing temperature. And
The alignment means releases the support state of the second substrate by the shape memory alloy by heating the shape memory alloy to a temperature higher than the processing temperature in the oxide film removal process, and lowers the second substrate directly below. Letting
Soldering device characterized by

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