KR100503411B1 - Method for fabricating Au-Sn based solder layer and solder bump - Google Patents

Abstract

We propose a low-cost formation process for solder bumps or solder layers made of Au-Sn-based alloys, which are mainly used as solder materials in the flux-free soldering process. In the present invention, after forming a two-layer structure of Au / Sn or a three-layer structure of Au / Sn / Au on a metal substrate, such as a multi-layer thin film metal or UBM (Under Bump metallurgy), it is heated to 280 ℃ or more solid Au Au-Sn-based solder is prepared by reacting Sn with a liquid phase. According to the present invention, an Au-Sn-based solder layer or solder bumps having a uniform composition can be manufactured very quickly in several tens of seconds. Therefore, the Au-Sn-based solder manufacturing process is lowered in price, and the variation in composition that may occur in the alloying process can be minimized, thereby making it possible to stabilize the flux-free solder joint in the subsequent process.

Description

Method for fabricating Au-Sn based solder layer and solder bump}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the packaging of semiconductor devices or optoelectronic devices, and more particularly to a solder fabrication technique of Au-Sn based alloys used as fluxless solder joint materials in bonding processes such as flip chip bonding. .

Conventionally, the solder bumps are fixed by attaching flux to solder pads and then reflowing by applying flux to the pads to which the solder bumps of the package are attached. Flux is a complex organic chemical that removes a metal oxide film formed on the surface of a solder ball and a pad made of copper (Cu) or nickel (Ni). However, the flux used in the reflow is not completely removed even if washed with an organic solvent, there is a problem that is attached as a residue to the surface or the junction of the solder bumps. Flux remaining without being removed from the joint continues to corrode the portion, causing leakage, and bubbles left in the joint as the solvent of the flux volatilizes reduce the joint strength, such as reducing the reliability of the joint. Therefore, the soldering process which does not use a flux, ie, the flux-free soldering process, came to be required. In particular, in the bonding process of the optoelectronic device, which is difficult to apply the cleaning process, the application of a flux-free soldering process is common.

Au-Sn-based alloy is mainly used as the flux-free soldering joint material, and an alloy of the typical composition is Au-20 (wt%) Sn. This composition has a eutectic temperature of 280 ℃, the temperature change of the liquid line according to the composition change is very large. Thus, slight compositional changes that occur during the manufacture of solder bumps or solder layers of Au-20 (wt%) Sn composition may be due to operating conditions in the flux-free soldering process, eg, heating temperature, applied static pressure. The yield of the process is reduced by changing the size and the like.

Therefore, the manufacturing process of the solder bump or solder layer of Au-20 (wt%) Sn composition has to be controlled within a very small compositional change, which is very difficult to implement by a process of direct alloy deposition. Reportedly, in the electrolytic plating process of Au-20 (wt%) Sn alloy, the content of Sn varies with a large deviation of about 10-42at% (6-30wt%) as the plating conditions change. Difficult to accurately implement -20 (wt%) Sn composition (W. Sun, DG Ivey, "Microstructural study of co-electroplated Au / Sn alloys", Journal of Materials Science, 36, p.757-766, 2001) . In addition, it is recognized that the alloy deposition process in a vacuum state such as thermal deposition, electron beam deposition or laser deposition is also very difficult to precisely implement the Au-20 (wt%) Sn composition due to the process characteristics.

Therefore, the technical problem to be achieved by the present invention is to provide a solder manufacturing technique that can minimize the occurrence of variations in the alloy composition during the manufacturing process of the Au-Sn-based solder bumps or solder layer.

In order to achieve the above technical problem, in the present invention, in place of the method of directly depositing the Au-Sn-based solder in the alloy state, by depositing a solder material in the form of a stack of Au / Sn or Au / Sn / Au, heat treatment process We propose a method for the alloying reaction through. Specifically, in the present invention, in order to manufacture the Au-Sn-based solder bump or solder layer, the metal layer in the order of two layers of Au / Sn or three layers of Au / Sn / Au on a multilayer thin film metal or UBM (Under Bump Metallurgy) After the deposition, the heat treatment at 280 ℃ or more alloying Au-Sn-based solder very quickly by the reaction of the solid Au layer and the liquid Sn layer.

The thickness of the Au layer and the Sn layer to be deposited is several tens to several micrometers, respectively, by controlling the thickness of each layer can ultimately control the composition of the alloy. Since the control of the film thickness to be deposited is relatively easy, it can be said that the composition of the alloy becomes easier. In addition, since the liquid phase is continuously interposed at the heat treatment temperature, the alloying reaction is completed within several tens of seconds. Therefore, according to the present invention, Au-Sn-based solder bumps or solder layers can be manufactured in a short time while reducing occurrence of deviation in the solder alloy composition.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. The objects and advantages of the present invention will become more apparent from the following description. However, embodiments of the present invention may be modified in many different forms, and the scope of the present invention should not be construed as being limited by the embodiments described below. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

(First embodiment)

1 to 3 are cross-sectional views illustrating a method of forming an Au—Sn based solder layer according to a first embodiment of the present invention.

First, referring to FIG. 1, Au / Sn stacking of Au and Sn, each of Au and Sn-based solder forming elements, is deposited only once in turn on the multilayer thin film metal 40. Form the structure 70. The thicknesses of the Au layer 50 and the Sn layer 60 can be designed through pre-calculation when setting the desired alloy composition. For example, when the Au-20 (wt%) Sn alloy solder is formed, the Au layer 50 may be deposited to be about 1.5 times the thickness of the Sn layer 60. Various methods such as thermal deposition, electron beam deposition, sputtering, pulsed laser deposition (PLD), electrolytic plating, electroless plating, and immersion deposition may be used to deposit Au and Sn.

To form a solder layer, there are a method of collectively forming a solder layer on a wafer, and a method of cutting a wafer into semiconductor chips and forming solder layers on individual semiconductor chips, respectively. It is preferable to form a solder layer on a wafer collectively from a viewpoint of saving manufacturing cost. However, the present invention can be applied to both of the above methods. The multilayer thin film metal 40 in this embodiment is a metal substrate for forming a layered solder, that is, a solder layer, and is formed on the substrate or the semiconductor chip 10. The present invention may be applied to a material (i.e., silicon wafer) from which a semiconductor chip is made, or may be applied to a substrate (silicon wafer, alumina plate, etc.). That is, when the chip | tip and board | substrate are considered, the solder interposed in the middle may be formed in a chip | tip, or may be formed in a board | substrate.

As shown in FIG. 1, the multilayer thin film metal 40 is formed to include an adhesion layer 20 and a solderable layer 30. First, the bonding layer 20 is formed by depositing titanium (Ti), chromium (Cr), or the like on the substrate or the semiconductor chip 10. Then, platinum (Pt), nickel (Ni), copper (Cu), cobalt (Co), iron (Fe), palladium (Pd), silver (Ag), vanadium (V) or nickel-vanadium (Ni-V) And the like to form a solder reaction metal layer 30.

Next, referring to FIG. 2, in order to achieve an Au-Sn-based solder alloy reaction in a case where flux is not applied or used, a reducing gas atmosphere or an inert gas atmosphere without exposing the Au / Sn layer structure 70 to the atmosphere Or heat-process (H) by heating to 280 degreeC or more in a high vacuum atmosphere. The gas forming the gas atmosphere may be nitrogen (N ₂ ), hydrogen (H ₂ ), argon (Ar) or a suitable combination thereof. When heated at 280 degreeC or more, Au is solid but Sn becomes liquid. Therefore, the alloy reaction between Au and Sn by liquid phase Sn is completed in a very fast time, usually several tens of seconds.

When the temperature of the heat treatment reaction is less than 280 ° C, the process Au-20 (wt%) Sn composition region having a melting point of 280 ° C is present in the solid phase rather than in the liquid phase, so that rapid alloying occurs at 280 ° C or higher as in the present invention. You can't expect a response. It was estimated that it took several tens of minutes to alloy the Au-20 (wt%) Sn composition region by solid phase reaction below 280 ° C. This is a very long time, which is inefficient to apply to the actual production process in the field. However, in the present invention, since the temperature of the heat treatment (H) is 280 ° C or more, the alloy reaction between Au and Sn is completed within several tens of seconds by reaction promoting action by liquefied Sn and Au-20 (wt%) Sn. . The method according to the invention is therefore very fast and therefore economical and efficient.

In order to heat above 280 ° C. according to the invention, hot plate heating, furnace heating, infrared heating, oven heating or laser beam irradiation can be used. However, the heating method is not limited thereto, and all possible methods of conduction heating, convection heating, or radiant heating method can be used. In addition, a heating device equipped with a conveyor for continuous production can be used to continuously produce a solder layer.

However, as in the present embodiment, when the Sn layer 60 is at the top, a Sn oxide film such as SnO ₂ and / or SnO is formed by atmospheric exposure, so that Au and Au are alloyed by the heat treatment (H) of FIG. 2. There is a fear that the complete reaction of Sn is suppressed due to the presence of such an oxide film. In order to remove this concern, a method of applying a flux (not shown) on the Sn layer 60 before the heat treatment (H) may be used to remove the Sn oxide film during the heat treatment (H) reaction. The role of the flux is to suppress the oxidation of the metal even during the heat treatment (H) because the oxide film is already formed so that the oxide film is dissolved to remove the oxide film and the oxidation inhibiting film is formed. Therefore, when the flux is applied and used, it is possible to achieve a complete reaction in the air without applying the reducing gas atmosphere, the inert gas atmosphere or the high vacuum atmosphere as described above. The flux used in this embodiment is not limited to a specially standardized material, and commercially available fluxes can be used. The flux after the heat treatment (H) is removed by ordinary washing with a hydrocarbon-based or tepen-based cleaner, or in the case of a water-washing type flux.

To remove the Sn oxide film formed without using the flux, the heat treatment (H) is performed at a temperature of 400 ° C. or higher in a reducing gas atmosphere. Although the temperature for alloying only needs to be 280 degreeC or more, in order to reduce and remove the Sn oxide film formed on the Sn layer 60, the temperature at the time of heat processing (H) is maintained at 400 degreeC or more. Then, the alloying reaction is completed within a few tens of seconds, but the time for heat treatment (H) is maintained longer than this so that the Sn oxide film in this case can be sufficiently reduced and removed.

3 schematically shows the microstructure change of the Au-Sn alloy solder layer 80 and the solder joint after the heat treatment (H) according to the present invention. The Au / Sn layered structure 70 of FIG. 1 is transferred to the Au-Sn alloy solder layer 80 through a heat treatment (H) reaction process. In addition, after the Au layer 50 on the multilayer thin film metal 40 of FIG. 1 is dissolved and reacted into molten Sn during the heat treatment (H) reaction and completely disappears, the solder reaction metal layer 30 in the multilayer thin film metal 40 ) Reacts with the Au—Sn alloy solder layer 80 to form the intermetallic compound layer 85 as shown in FIG. 3. The intermetallic compound layer 85 is made of a binary compound such as X (solder reactive metal layer element) -Sn, or a ternary compound such as X-Sn-Au.

The formation of an intermetallic layer means the formation of a complete solder joint. However, the intermetallic compound layer grown to an excessive thickness also means a decrease in the reliability of the solder joint against external stresses and joint failure due to excessive consumption of the solder reaction metal layer. Therefore, in the present invention, the thickness of the intermetallic compound layer 85 should be controlled through an appropriate heat treatment (H) time. In order to prevent excessive generation of the intermetallic compound layer 85 by the reaction between the solder reaction metal layer 30 and the Au—Sn alloy solder layer 80, in addition to the method of controlling by time, the multilayer thin film metal 40 in FIG. The Au layer 50 is deposited thicker than the theoretically calculated thickness when the alloy composition is set so that Au or Au-rich layer remains on the multilayer thin film 40 even after heat treatment (H). There is also.

(2nd Example)

4 is a cross-sectional view illustrating a method of forming an Au—Sn based solder layer according to a second embodiment of the present invention. In FIG. 4, the same elements as those described in the first embodiment are denoted by the same reference numerals as in FIGS. 1 and 2, and repeated descriptions thereof will be omitted.

Referring to FIG. 4, Au and Sn are deposited one by one on the multilayer thin film 40, and then Au is deposited again to form the primary Au layer 50, the Sn layer 60, and the secondary Au layer 50 ′. An Au / Sn / Au laminate structure 75 is formed. The sum of the thicknesses of the primary Au layer 50 and the secondary Au layer 50 'and the thickness of the Sn layer 60 are designed through calculation at the time of setting the desired alloy composition. For example, when forming Au-20 (wt%) Sn alloy solder, the sum of the thicknesses of the primary Au layer 50 and the secondary Au layer 50 'is deposited at about 1.5 times the thickness of the Sn layer 60. . Therefore, in order to form an Au / Sn / Au laminated structure 75 having a total thickness of 5 μm to form an Au-20 (wt%) Sn alloy solder, 1.5 μm primary Au layer 50 and 2 μm Sn The layer 60 and the 1.5 μm secondary Au layer 50 ′ may be manufactured. As such, usually, the thicknesses of the primary Au layer 50 and the secondary Au layer 50 'are designed to be the same. However, depending on the heat treatment method and the temperature distribution in the Au / Sn / Au layer structure 75 during heating, the sum of the thicknesses of the primary Au layer 50 and the secondary Au layer 50 'is kept constant, but the primary Au layer The thickness of each of the 50 and the secondary Au layer 50 'may be slightly added or subtracted.

Next, the Au / Sn / Au laminated structure 75 is heated to 280 ° C. or higher to perform a heat treatment (H) for alloying liquid Sn and solid Au while alloying Sn. The result after heat processing H is the same as that of FIG.

In this embodiment, since the secondary Au layer 50 'is at the top, there is little fear that Sn oxide film will be generated as in the first embodiment even when exposed to the atmosphere. Therefore, in this case, there is an advantage that a complete reaction of Au and Sn can be achieved only by heat treatment (H) in a reducing gas atmosphere, an inert gas atmosphere, or a high vacuum atmosphere.

(Third Embodiment)

5 to 7 are cross-sectional views illustrating a method of forming an Au—Sn based solder bump according to a third embodiment of the present invention. 5 to 7, the same elements as those described in the first embodiment are denoted by the same reference numerals as in FIGS. 1 to 3, and repeated descriptions thereof will be omitted.

Referring to FIG. 5, Au / Sn stacked structure 70a formed of Au layer 50a and Sn layer 60a by depositing Au and Sn, which are Au—Sn based solder forming elements, once on the UBM 40a one by one in turn. ). UBM (40a) is a metal substrate for forming a bump-shaped solder, that is, a solder bump, a multi-layered thin film made of a bonding layer 20 and a solder reaction metal layer 30 on the substrate or semiconductor chip 10 as shown in FIG. 40) is formed, and then patterned into a square or a circle. Reference numerals 20a and 30a denote the patterned bonding layer 20 and the solder reaction metal layer 30, respectively.

In order to form the Au / Sn stacked structure 70a, a photoresist pattern S is formed as shown in FIG. 5, and then Au and Sn are deposited, and unnecessary portions are lifted off. Can be. For example, a photoresist pattern S having a circular opening is formed on the UBM 40a. The area of the opening can be similar to or larger than the area of UBM 40a. Au and Sn are deposited on top of each other one by one. As a result, an Au / Sn layer structure 70a including the Au layer 50a and the Sn layer 60a is formed in the opening. The Au layer 50b and the Sn layer 60b deposited on the photoresist pattern S may be removed while the photoresist pattern S is lifted off.

Referring to FIG. 6, the Au layer 50b and the Sn layer 60b in FIG. 5 are also removed while the photoresist pattern S is lifted off. For example, the resultant of FIG. 5 is immersed in a resist removing liquid and heated / vibrated in the removing liquid or sprayed using an air gun. As a result, only the Au / Sn stacking structure 70a remains on the UBM 40a. Subsequently, the Au / Sn laminated structure 70a is heated to 280 ° C. or higher in a reducing gas atmosphere, an inert gas atmosphere, or a high vacuum atmosphere to be subjected to a heat treatment (H). At 280 ° C or higher, the Sn and Au-20 (wt%) Sn composition becomes a liquid phase, so that the alloying reaction is very fast, and the Au / Sn layer structure 70a is promoted to a bump shape by the surface tension effect of the liquid phase.

In the present embodiment, however, as in the first embodiment, since the Sn layer 60a is at the top, a Sn oxide film such as SnO ₂ and / or SnO is likely to be formed during atmospheric exposure. The Sn oxide film not only suppresses the complete reaction of Au and Sn in the heat treatment (H) but also suppresses the shape change of the Au-Sn alloy metal. Therefore, as described in the first embodiment, the heat treatment (H) is performed using flux, or the heat treatment (H) temperature is increased to 400 ° C. or higher using a reducing gas atmosphere, and the alloy reaction and the reduction reaction of the Sn oxide film are performed for a long time.

FIG. 7 schematically shows the microstructure change of the Au-Sn alloy solder bumps 80 'and the solder joint after performing the heat treatment H of FIG. 6 for several tens of seconds. In FIG. 5, the rectangular Au / Sn layered structure 70a deposited in the circular opening is transferred to the Au-Sn alloy solder bump 80 ′ through a heat treatment (H) reaction, while its shape has a melting point of 280 ° C. The branches are spherical due to the liquefaction and surface tension effects of the Au-20 (wt%) Sn region. Once formed, the shape of the solder bumps is maintained by the surface tension. The larger the total thickness of the Au / Sn stacked structure 70a, the closer the spherical shape of the Au-Sn alloy solder bumps 80 'after the heat treatment (H) is.

After the Au layer 50a on top of the UBM 40a of FIG. 5 is dissolved and reacted into molten Sn during the heat treatment (H) reaction, the solder reaction metal layer 30a in the UBM 40a is Au-Sn. By reacting with the alloy solder bump 80 ′, an intermetallic compound layer 85 is formed on the UBM 40a as shown in FIG. 7. As in the first embodiment, it is necessary to appropriately adjust the thickness of the intermetallic compound layer 85.

Experimental Example

FIG. 8 is a scanning electron micrograph showing a microstructure of an Au / Sn / Au stacked structure 75 formed by sequentially depositing Au, Sn, and Au according to a second embodiment of the present invention. A silicon wafer was used as the substrate 10. A Ti layer having a thickness of 0.05 µm was formed by sputtering thereon as a bonding layer. A Pt layer having a thickness of 0.2 탆 was formed by sputtering thereon as the solder reaction metal layer. As described above, Au and Sn are thermally deposited one by one on the multilayer thin film metal 40 composed of Ti / Pt, and then Au is thermally deposited again to form the primary Au layer 50, the Sn layer 60, and the secondary Au layer 50. An Au / Sn / Au laminate structure 75 consisting of ') was formed. In order to form an Au-20 (wt%) Sn alloy solder layer, a first Au layer 50 of 1.5 mu m, a Sn layer 60 of 2 mu m, and a second Au layer 50 'of 1.5 mu m were manufactured. It was.

8, the first Au layer 50 and the Sn layer 60 are successively deposited in a vacuum state on the multilayer thin film metal 40, and then the second Au layer 50 'is formed by breaking the vacuum. In relation to this, at the boundary between the primary Au layer 50 and the Sn layer 60, the intermetallic compound layer generated by the reaction of the primary Au layer 50 and the Sn layer 60 during the heating process during the thermal deposition. Although the boundary is vaguely observed, an oxide film is formed at the Sn layer 60 and the secondary Au layer 50'interface due to oxidation phenomenon on the upper surface of the Sn layer 60, thereby suppressing the reaction during the subsequent heat deposition heating. It can be seen that the interface between the Sn layer 60 and the secondary Au layer 50 'is clearly observed. Prior to the heat treatment, flux (not shown) was applied onto the secondary Au layer 50 '.

FIG. 9 illustrates an Au-20 (wt%) Sn alloy solder layer 80 formed by maintaining the Au / Sn / Au stack structure 75 of FIG. 8 at 290 ° C. for 5 seconds according to a second embodiment of the present invention. Scanning electron micrograph showing. As can be seen in FIG. 9, a very rapid reaction between the Sn layer 60 in FIG. 8 and the primary and secondary Au layers 50, 50 ′ above and below, that is, solid Au into the molten Sn layer. It can be seen that the solder layer 80 having the Au-20 (wt%) Sn composition was formed as the layer was dissolved. In addition, the Au-20 (wt%) Sn solder layer 80 and the multilayer thin film were reacted with a Pt solder reaction metal layer in the multilayer thin film metal 40. It can be seen that the ternary intermetallic compound layer 85 of Pt-Au-Sn was formed between the metals 40. As shown in FIG. 9, the formation of the intermetallic compound layer 85 means that a complete solder joint is formed. In particular, no gaps or defects can be observed at the interface of the joint. Therefore, it can be confirmed that the joint structure of the perfect solder layer is formed.

As mentioned above, the present invention has been described in detail with reference to preferred embodiments, but the present invention is not limited to the above embodiments, and various modifications may be made by those skilled in the art within the technical idea of the present invention. It is obvious. For example, although not described with reference to the specific drawings, a method of manufacturing a solder bump after forming an Au / Sn / Au laminate structure by combining the second and third embodiments of the present invention is described herein. Can be inferred by one skilled in the art. Accordingly, the invention includes alternatives, modifications and equivalents that may be included within the spirit and scope of the invention as defined by the appended claims.

In the present invention, Au-Sn-based solder bumps or solder layers are prepared by continuously depositing Au and Sn layers of several tens of micrometers in thickness and then reacting the Au and Sn layers through heat treatment.

Instead of depositing Au-Sn in the alloy state, it is possible to produce solder bumps or solder layers by depositing pure Au and Sn, respectively, so that it is relatively easy to precisely implement a desired composition and to deposit pure metal films according to the deposition time. By monitoring the thickness, Au-Sn-based solder alloys of any composition can be realized.

Since the thickness of several tens of micrometers of Au and Sn deposition is about the solder layer or the solder bump height level, the solder having the height that is typically desired to be realized even if the An and Sn layer deposition numbers are maintained only two to three times is deposited. Layers or solder bumps can be fabricated to simplify the process. Of course, manufacturing costs are also lowered.

In addition, since the alloying reaction is promoted by the Sn and Au-20 (wt%) Sn in the liquid phase at the heat treatment temperature, the alloying reaction is completed within several tens of seconds.

Therefore, according to the present invention, it is possible to manufacture the solder bumps or the solder layer in a short time by reducing the occurrence of deviation in the solder alloy composition during the manufacturing process of the Au-Sn-based solder bumps or solder layer. In other words, the Au-Sn-based solder manufacturing process is lowered in price, and the variation of the composition that can occur during the alloying process can be minimized, thereby stabilizing the solder joint in the subsequent process.

1 to 3 are cross-sectional views illustrating a method of forming an Au—Sn based solder layer according to a first embodiment of the present invention.

4 is a cross-sectional view illustrating a method of forming an Au—Sn based solder layer according to a second embodiment of the present invention.

5 to 7 are cross-sectional views illustrating a method of forming an Au—Sn based solder bump according to a third embodiment of the present invention.

8 and 9 are scanning electron micrographs showing the results of experiments performed in accordance with a second embodiment of the present invention.

<Description of the code | symbol about the principal part of drawing>

10 substrate or semiconductor chip 20 bonding layer

30: solder reaction metal layer 40: multilayer thin film metal

50, 50 ': Au layer 60: Sn layer

70: Au / Sn laminated structure 75: Au / Sn / Au laminated structure

H: heat treatment S: photoresist pattern

80: Au-Sn solder layer 80 ': Au-Sn solder bump

85: intermetallic compound layer

Claims (13)

Depositing Au and Sn once only once in a thickness of several tens of micrometers on a metal substrate to form an Au / Sn laminate structure; And And heating the Au / Sn laminate to 280 ° C.-400 ° C. to liquefy Sn while alloying liquid Sn and solid Au. Depositing Au and Sn on the metal substrate one by one in thickness of several tens of 탆, and then depositing Au in several tens of 탆 to form an Au / Sn / Au laminate structure; And And heating the Au / Sn / Au laminated structure to 280 ° C.-400 ° C. to liquefy Sn while alloying liquid Sn and solid Au. The method of claim 1, wherein the metal substrate is a multilayer thin film metal formed on a substrate or a semiconductor chip to form a layered solder. The Au-Sn system according to claim 1 or 2, wherein the metal substrate is an under bump metallurgy (UBM) formed by forming a multi-layered thin film metal on a substrate or a semiconductor chip to form a bump solder. Solder Manufacturing Method. delete The Au-Sn-based solder according to claim 1 or 2, wherein the Au layer is deposited to be 1.5 times the Sn layer thickness in order to form an Au-20 (wt%) Sn alloy solder. Manufacturing method. The method of claim 1, wherein the Au and Sn are deposited by thermal deposition, electron beam deposition, sputtering, pulsed laser deposition (PLD), electrolytic plating, electroless plating, or immersion deposition. Au-Sn-based solder manufacturing method characterized in that. The Au-Sn solder manufacturing method according to claim 1 or 2, wherein hot plate heating, furnace heating, or laser beam irradiation is used to heat the laminated structure. The Au-Sn-based solder manufacturing method according to claim 1 or 2, wherein a heating device equipped with a conveyor is used for continuous production in order to heat the laminated structure and continuously manufacture the solder. Way. The method of claim 1, wherein the heat treatment is performed in a reducing gas atmosphere, an inert gas atmosphere, or a high vacuum atmosphere. The Au-Sn of claim 1 or 2, wherein a flux is further applied on the laminated structure before the heat treatment step, thereby removing the native oxide film existing on the laminated structure in the heat treatment step. Solder manufacturing method. 12. The method of claim 11, wherein the heat treatment is performed in an atmosphere, a reducing gas atmosphere, an inert gas atmosphere, or a high vacuum atmosphere. The method of claim 1, wherein the heat treatment step is performed in a reducing gas atmosphere so that the natural oxide film existing on the stacked structure is removed in the heat treatment step.