JPH05243232A - Manufacture of solder bump electrode - Google Patents

Abstract

PURPOSE:To make it possible to easily produce a plurality of solder bump electrodes which are different from each other in composition and size at desired areas on a circuit board individually diced, and also to control the composition and size of the solder bump electrode in a desired manner. CONSTITUTION:A substrate 100 for the formation of an electrode and a semiconductor substrate 200 are positioned in such a manner that a soldering plating 6 formed on a metal layer 3, which is not wettable with solder, of the substrate 100 and a solder connection metal layer 10, which is wettable with solder, formed on the substrate 200 are opposite to each other. The solder plating 6 and the metal layer 10 are brought into contact with each other, and the solder plating 6 is fused by heating at least one of the substrates 100 and 200. Then, the substrates 100 and 200 are isolated from each other, whereby a solder bump 13 is produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a solder bump electrode which is a metal projection electrode.

[0002]

2. Description of the Related Art Conventionally, as a method of forming a solder bump electrode, there is a first conventional example shown in FIG. In the method of forming the solder bump electrode, as shown in FIG. 10A, first, the semiconductor layer 51, the conductor terminal 52, and the insulating protective film 53
A metal layer 54 for solder connection is formed on the conductor terminal 52 and the insulating protective film 53 of the semiconductor substrate made of and by sputtering or vapor deposition, and a resist 55 is further applied thereon, and the conductor terminal 52 is formed on the conductor terminal 52 by photolithography. Resist 55
Is removed to form an opening 56 in which the solder connecting metal layer 54 is exposed.

Next, electrolytic plating is performed using the solder connecting metal layer 54 as a cathode, and solder is supplied to the opening 56 of the resist 55 to form a solder plating 57.

Next, as shown in FIG. 10B, the resist 55 is removed with a solvent or the like, and the resist 5 is removed.
The solder connecting metal layer 54 in the unnecessary region exposed by the removal of 5 is removed by etching.

Finally, the solder plating 57 is melted,
As shown in FIG. 10C, the solder bump 57 is formed by making the solder plating 57 spherical by the surface tension of the solder.

Next, a second conventional example is shown in FIG. Figure 1
As shown in FIG. 1, in this conventional example, a metal layer 64 for solder connection is sputtered or vapor-deposited on the conductor terminal 62 and the insulating protective film 63 of the semiconductor substrate 61 including the semiconductor layer 61, the conductor terminal 62, and the insulating protective film 63. The metal layer 64 not facing the conductor terminal 62 is removed by the lift-off method, and the solder connecting metal layer 64 is left only on the conductor terminal 62.

Next, a metal mask 65 having an opening in a region facing the solder connecting metal layer 64 is provided on the insulating protective film 63, and a metal forming a solder is formed on the solder connecting metal layer 64. 66a and 66b are sequentially deposited. For example,
After depositing lead on the metal layer 64, tin is deposited.

Next, the metal mask 65 is removed from the semiconductor substrate, and finally, the metals 66a and 66b constituting the solder are melted so that the metals 66a and 66b are interdiffused and spherical due to surface tension. By
Form solder bump electrodes.

Next, FIG. 12 shows a third conventional example. In this conventional example, as shown in FIG. 12, a solder connecting metal layer 74 is sputtered on the conductor terminal 72 and the insulating protective film 73 of the semiconductor substrate 71 including the semiconductor layer 71, the conductor terminal 72, and the insulating protective film 73. The metal layer 74 is formed by vapor deposition, and the metal layer 74 in the region away from the connection with the conductor terminal 72 is removed by etching as in the conventional example shown in FIG. Leave 74.

Next, using the wire bonder 80, the solder balls 8 made of solder supplied from the capillaries 81.
2 is bonded onto the solder connecting metal layer 74, and the solder wire portion 83 is cut. Then, finally, the solder ball 82 which is deformed at the time of bonding and is joined to the cut solder wire portion 83 is melted to be spherical.

[0011]

In the conventional example shown in FIGS. 10 and 11, in which the semiconductor substrate itself needs to be subjected to electrolytic plating vapor deposition for forming solder bump electrodes, the semiconductor substrate individually separated from the wafer. That is, there is a problem that it is difficult to apply to the semiconductor substrate after dicing. This is because it is difficult in the manufacturing process to supply solder to the semiconductor substrate after being individually diced by electrolytic plating or vapor deposition.

As a case where the solder bump electrodes must be formed on the semiconductor substrate after dicing, for example, there is a case where a semiconductor substrate is obtained from an external maker without manufacturing the semiconductor substrate wafer in-house.

Further, in the conventional example shown in FIGS. 10 and 11, since the solder is supplied to the semiconductor substrate by electrolytic plating or vapor deposition, a plurality of solder bump electrodes having different compositions and sizes are provided in the same semiconductor substrate. Is difficult to form. Further, it is difficult to form solder bump electrodes on a semiconductor substrate on which metal protruding electrodes such as Au and Cu having a melting point higher than that of solder and a hardness higher than that of solder are already formed.

Further, in the conventional example using electrolytic plating on the semiconductor substrate, since the dimension in the width direction is larger than the height of the solder plating, that is, the plating thickness, the solder bumps relatively large with respect to the narrow pitch. There is also a problem that it is difficult to form electrodes and solder bump electrodes having a large plating thickness.

Further, as shown in FIG. 12, the conventional example using the wire bonder does not have the above-mentioned problems, but FIG.
0, the time required to form the solder bump electrodes is longer than that of the conventional example shown in FIG. 11, and the required time for formation increases as the number of solder bump electrodes to be formed increases, and the yield decreases. There is also a problem that the size of the solder bump electrode is likely to vary.

Therefore, an object of the present invention is to easily form a plurality of solder bump electrodes having different compositions and sizes at desired portions on individually diced circuit boards, and to obtain the solder bump electrodes having desired compositions and sizes. An object of the present invention is to provide a method of forming a solder bump electrode that can be controlled in size.

[0017]

In order to achieve the above object, the present invention produces an electrode-forming substrate by forming an insulating film which does not wet the solder on a metal plate which does not wet the solder, and then, , The solder of the circuit board on which the circuit element is formed is wet, the insulating film of the electrode forming substrate in the area corresponding to the solder connecting metal layer is removed, and the metal layer below the insulating film does not wet the solder. Form an exposed opening, and then supply solder to the opening of the insulating film by electrolytic plating using a metal layer of the electrode forming substrate that does not wet the solder as a common electrode to perform solder plating on the opening. And then aligning the circuit board and the electrode forming board so that the solder plating of the electrode forming board and the solder connecting metal layer of the circuit board face each other, and then, Circuit board or electrode type At least one of the soldering substrates is heated to a temperature equal to or higher than the melting point of the solder to melt the solder plating, and the solder plating is brought into contact with the solder connecting metal layer, and then the circuit board and the electrode forming board are formed. Are separated from each other, and the molten solder plating is transferred from the metal layer exposed in the opening of the electrode forming substrate where the solder is not wet to the solder connecting metal layer where the solder of the circuit substrate is wet.

[0018]

According to the solder bump electrode forming method of the present invention,
Align the electrode forming substrate and the semiconductor substrate so that the solder plating formed on the metal layer of the electrode forming substrate that does not wet the solder and the solder connecting metal layer formed on the semiconductor substrate that wets the solder face each other. Then, the solder plating and the metal layer for solder connection are brought into contact with each other, and at least one of the semiconductor substrate and the electrode forming substrate is heated to prevent the solder of the electrode forming substrate different from the circuit substrate from getting wet. Since the solder bump electrodes are formed on the circuit board by melting the solder plating formed on the metal and transferring the melted solder plating to the solder connecting metal layer where the solder of the circuit board gets wet, unlike the conventional example. It is not necessary to subject the circuit board itself to electrolytic plating or vapor deposition for forming solder bump electrodes. Therefore, according to the method for forming solder bump electrodes of the present invention, it is not necessary to provide a difficult step of supplying solder to individually diced circuit boards by electrolytic plating or vapor deposition. It is possible to easily form the solder bump electrode on the solder-connecting metal layer at the position.

Further, molten solder plating is applied from the electrode forming substrate to a solder connecting metal layer at an arbitrary position on the circuit substrate over a plurality of times while changing the composition and size as necessary. By transferring, it becomes possible to form a solder bump electrode having a desired composition and size on a desired solder connecting metal layer on the circuit board.

Further, according to the present invention, unlike the conventional example,
Since it is not necessary to perform electrode plating or vapor deposition on the circuit board itself in order to form solder bump electrodes, a metal protruding electrode made of Au, Cu or the like having a melting point higher than that of solder and a hardness higher than that of solder has already been formed. Solder bump electrodes can be easily formed on the circuit board. The metal projection electrode made of Au, Cu or the like prevents the semiconductor substrate from tilting or controls the connection height when the semiconductor substrate is flip-chip connected after the solder bump electrodes are formed on the semiconductor substrate. Play a role.

As described above, according to the present invention, various forms of bump electrodes can be easily realized on the circuit board according to the application.

[0022]

The present invention will be described in detail below with reference to the embodiments shown in the drawings.

First, a first embodiment of the present invention will be described.
In order to manufacture the electrode-forming substrate 100 shown in FIG. 1A, a metal (Ti, W, Ti) that does not get wet with solder is placed on an insulating substrate 2 such as ceramic having rigidity and heat resistance higher than the melting point of solder.
Insulator which has heat resistance and excellent adhesion between the metal layer 3 made of Mo, Nb, Cr, Be, Zr, etc., and which does not get wet with solder.
An insulating film 4 made of (SiN, SiO ₂ , polyimide, etc.) is formed.

On the other hand, the electrode structure of the semiconductor substrate as the circuit substrate on which the solder bump electrodes are formed will be described.
FIG. 3 shows a semiconductor substrate 200 including a semiconductor layer 7, an insulating protective film 8 and a conductor electrode 9, and a conductor electrode 9 of the semiconductor substrate 200.
The metal layer 10 for solder connection formed above is shown. Conductor electrode 9
Consists of Al or Au. The metal layer 1 for solder connection
0 is a metal (C
u, Ni, Pt, Pd, etc.) and a metal (C which has good adhesion and prevents solder from diffusing into the metal layer).
(r, TiW, NiCr, Ta, etc.) and a metal layer made of metal (Au, etc.) for improving wettability with respect to solder. The metal layer 10 for solder connection
The metal layer constituting the above is provided on the semiconductor substrate 200 by sputtering or the like, and is patterned only by the photolithography method to be left only on the conductor electrode 9.

Next, the insulating film 4 of the electrode forming substrate 100 shown in FIG. 1A in a region corresponding to the solder connecting metal layer 10 formed on the semiconductor substrate 200 shown in FIG.
It is removed by photolithography, and the metal layer 3 under the insulating film 4 is exposed in the above region and has a diameter of 70 to 10
The opening 5 of about 0 μm is formed.

Next, using the metal layer 3 exposed from the opening 5 of the electrode forming substrate 100 as a cathode, solder is supplied to the opening 5 of the insulating film 4 to open the opening 5 as shown in FIG. The solder plating 6 having a thickness of about 40 to 50 μm is formed on the substrate 5. The amount of solder of the solder plating 6 is set as necessary depending on the pitch of the openings 5 and the like. The composition of the solder is, for example, Sn: Pb = 60: 40, Sn: Pb = 10: 90.
Etc., depending on the application. In addition, as the solder, In
Needless to say, a low-melting-point solder to which, for example, is added can be used if necessary.

Next, as shown in FIG. 4, the semiconductor substrate 200 is held by a flip chip bonder having a suction tool 11 and a vacuum hole 12, and the electrode forming substrate 100 is attached to the semiconductor substrate 200 by using the flip chip bonder. The electrode forming substrate 100 and the semiconductor substrate 200 are aligned so that the formed solder plating 6 and the solder connecting metal layer 10 formed on the semiconductor substrate 200 face each other.

Next, the solder-connecting metal layer 10 is pressed against and brought into contact with the solder plating 6, and at least one of the semiconductor substrate 200 and the electrode-forming substrate 100 is heated to the melting point of the solder or higher. Then, the solder plating 6 is melted.

Next, as shown in FIG. 4B, the semiconductor substrate 200 and the electrode forming substrate 100 are separated from each other. At this time, the melted solder plating 6 does not wet the metal layer 3 of the electrode forming substrate 100, but it does well wet the solder connecting metal layer 10 formed on the semiconductor substrate 200. As shown in B), the molten solder plating 6 becomes a substantially spherical solder bump 13 due to surface tension, and is transferred from the metal layer 3 of the electrode forming substrate 100 to the solder connecting metal layer 10 formed on the semiconductor substrate 200. To be done. The transfer is performed due to the difference in solder wettability between the metal layer 3 and the solder connecting metal layer 10.

According to the above embodiment, the semiconductor substrate 20
The solder connecting metal on the electrode forming substrate 100 different from 0 melts the solder plating 6 formed on the metal layer 3 where the solder does not wet, and the molten solder plating 6 wets the solder formed on the semiconductor substrate 200. Since the solder bump electrodes 13 are formed on the semiconductor substrate 200 by transferring to the layer 10, unlike the conventional example, it is not necessary to subject the semiconductor substrate 200 itself to electrolytic plating or vapor deposition for forming the solder bump electrodes. Therefore, according to the method of forming the solder bump electrodes of the above-described embodiment, it is not necessary to perform the difficult process of supplying the solder to the individually diced semiconductor substrates by electrolytic plating or vapor deposition, and the individually diced semiconductor substrates 200 can be formed. Solder connection metal layer 10 at any location of
Therefore, the solder bump electrode can be easily formed.

Before transferring the solder plating 6, the solder plating 6 formed on the electrode forming substrate 100 is transferred.
Alternatively, by applying flux to the solder connecting metal layer 10 formed on the semiconductor substrate 200, the wettability of the molten solder plating 6 to the solder connecting metal layer 10 is improved, and the solder plating 6 is transferred. Can be made particularly good.
However, in the case of applying the flux, it is necessary to wash the flux with a solvent after forming the solder bumps 13.

Next, a second embodiment will be described with reference to FIG.

In this embodiment, the metal layers 10 for solder connection at both ends of the semiconductor substrate 200 including the semiconductor layer 7 are provided with metal protrusions made of Au, Cu or the like having hardness higher than solder and higher than solder. It differs from the first embodiment (FIGS. 1 to 4) described above only in that the electrodes 14 and 14 are already formed. Therefore, the same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted, and the points different from the first embodiment will be mainly described.

The metal protrusion electrodes 14 and 14 prevent the semiconductor substrate 200 from tilting when the semiconductor substrate 200 is flip-chip connected after the solder bump electrodes are formed on the semiconductor substrate 200, and the connection height is increased. It plays a role such as controlling.

In this embodiment, the semiconductor substrate 20 described above is used.
If the thickness of the metal protruding electrodes 14, 14 formed on the solder-connecting metal layer 10 formed in 0 is smaller than the thickness of the solder plating 6 on the insulating film 4 of the electrode forming substrate 100, the first
In the same manner as in the above embodiment, by heating at least one of the semiconductor substrate 200 and the electrode forming substrate 100 to a temperature equal to or higher than the melting point of solder, the solder connection metal layer 10 formed on the semiconductor substrate 200 is provided with the electrode forming electrodes. Board 10
The solder plating 6 formed to 0 can be transferred in a molten state.

When the thickness of the metal projection electrode 14 is larger than the thickness of the solder plating 6, the solder plating 6 is formed by heating at least the electrode forming substrate 100 to the melting point of the solder or higher. The molten solder plating 6 is melted into a substantially spherical shape by surface tension, and the thickness of the molten solder plating 6 on the insulating film 4 is made larger than the thickness of the metal projection electrodes 14 and 14. It may be transferred to the metal layer 10 for solder connection formed in the above. FIGS. 6 (A) and 6 (B) show how the solder plating 6 melts and becomes substantially spherical due to surface tension, and the thickness on the insulating film 4 increases.

Next, a third embodiment will be described with reference to FIG.

In this embodiment, the solder bump electrode 17 is formed on the semiconductor substrate 200 including the semiconductor layer 7 according to the forming method of the first embodiment, and then the solder bump electrode 17 is formed according to the forming method of the second embodiment. By transferring the solder plating 18 having a melting point higher than that of the bump electrode 17 to the solder connecting metal layer 10 formed on the semiconductor substrate 200, as shown in FIG. 7B, the solder connecting formed on the semiconductor substrate 200 is performed. Solder bump electrodes 19, 19 are formed on the metal layer 10 for use. Thus, as shown in FIG. 7B, a plurality of solder bump electrodes 17 and 19 having different melting points can be formed on one semiconductor substrate 200.

Next, a fourth embodiment will be described with reference to FIG. In this embodiment, small-sized first solder bump electrodes 20, 20 are formed on the semiconductor substrate 200 including the semiconductor layer 7 according to the forming method of the first embodiment, and then the second solder bump electrodes 20, 20 are formed.
According to the forming method of the above embodiment, the solder bump electrode 20 is formed.
8 is obtained by transferring the solder plating 21 having a larger plating thickness and a larger size than the solder plating used for forming the solder to the metal layer 10 for solder connection formed on the semiconductor substrate 200.
As shown in (B), large-sized second solder bump electrodes 22, 22 are formed on the solder connecting metal layer 10. Thus, as shown in FIG. 7B, one semiconductor substrate 200
It is possible to form a plurality of solder bump electrodes 20 and 22 having different sizes.

Next, a fifth embodiment will be described with reference to FIG. In this embodiment, the solder bump electrodes 13 are formed on the semiconductor substrate 200 including the semiconductor 7 according to the forming method of the first embodiment, and then the solder plating 6 is formed according to the forming method of the first embodiment. Electrode forming substrate 10
By transferring the solder plating 6 corresponding to the desired solder connection metal layer 10 from 0 to the solder bump electrodes 13 formed on the desired solder connection metal layer 10 formed on the semiconductor substrate 200 in a molten state. , As shown in FIG. 9 (B), 1
A plurality of solder bump electrodes 23, 13 having different sizes can be formed on one semiconductor substrate 200.

Moreover, according to the fifth embodiment, the molten solder plating is transferred from the electrode forming substrate 100 to the same solder connecting metal layer 10 formed on the semiconductor substrate 200 a plurality of times. Therefore, the amount of solder plating per transfer can be suppressed. That is, according to this embodiment, as compared with the case where the solder bump electrode is formed by only one transfer of the solder plating, the solder plating having a small plating thickness and having a small lateral spread is transferred multiple times. Therefore, high solder bump electrodes can be formed on the semiconductor substrate 200 with a narrow pitch.

In the above first to fifth embodiments, the case where the solder bump electrodes are formed on the semiconductor substrate 200 as a circuit substrate has been described, but the circuit substrate is not limited to the semiconductor substrate, and any circuit may be used. It may be a substrate.

In the first to fifth embodiments described above, the substrate provided with the insulating substrate 2 shown in FIG. 1 (A) is used as the electrode forming substrate 100, but as shown in FIG. 1 (B). In addition, since the insulating substrate 2 is not provided, the thickness of the insulating substrate 2 is large and the solder is not wet (Ti, W, Mo, Nb, Cr, Be, Zr, etc.)
You may use the electrode formation substrate 101 provided with the metal plate 1 consisting of.

[0044]

As is apparent from the above description, according to the method for forming the solder bump electrodes of the present invention, the solder plating formed on the metal of the electrode forming substrate, which is different from the circuit substrate, is not wet by the solder. Since the solder bump electrodes are formed on the circuit board by melting and transferring the melted solder plating to the solder connecting metal layer where the solder of the circuit board is wet,
Unlike the conventional example, there is no need to subject the circuit board itself to electrolytic plating or vapor deposition for forming solder bump electrodes. Therefore, according to the method for forming a solder bump electrode of the present invention, the need for the difficult step of supplying solder to individually diced circuit boards by electrolytic plating or vapor deposition is eliminated,
It is possible to easily form the solder bump electrodes on the solder-connecting metal layer at an arbitrary position on the individually diced circuit board.

Further, the solder plating melted from the electrode forming substrate to the solder connecting metal layer at an arbitrary position on the circuit board is changed over a plurality of times while changing the composition and size as necessary. By transferring, it is possible to form a solder bump electrode having a desired composition and size on a desired solder connecting metal layer on the circuit board.

Further, according to the present invention, unlike the conventional example,
Since it is not necessary to perform electrolytic plating or vapor deposition for forming solder bump electrodes on the circuit board itself, metal projection electrodes made of Au, Cu, etc. having a higher melting point than solder and a higher hardness than solder have already been formed. Solder bump electrodes can be easily formed on the circuit board. The metal projection electrode made of Au, Cu or the like prevents the semiconductor substrate from tilting or controls the connection height when the semiconductor substrate is flip-chip connected after the solder bump electrodes are formed on the semiconductor substrate. Play a role.

As described above, according to the present invention, various forms of bump electrodes can be easily realized on the circuit board according to the application.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a first embodiment of an electrode forming substrate of the present invention.

FIG. 2 is a cross-sectional view of the electrode-forming substrate that is solder-plated.

FIG. 3 is a cross-sectional view showing a structure of an electrode portion of the semiconductor substrate of the above embodiment.

FIG. 4 is a diagram showing a method of transferring solder from the electrode forming substrate to the electrode portion of the semiconductor substrate in the above embodiment.

FIG. 5 is a cross-sectional view illustrating a second embodiment.

FIG. 6 is a cross-sectional view showing how the solder plating of the electrode forming substrate is melted into a substantially spherical shape due to surface tension in the above embodiment.

FIG. 7 is a cross-sectional view illustrating a third embodiment.

FIG. 8 is a sectional view illustrating a fourth embodiment.

FIG. 9 is a sectional view for explaining a fifth embodiment.

FIG. 10 is a sectional view illustrating a first conventional example in which a solder bump electrode is formed by plating.

FIG. 11 is a cross-sectional view illustrating a second conventional example in which solder bump electrodes are formed by a vapor deposition method using a metal mask.

FIG. 12 is a cross-sectional view illustrating a third conventional example in which a solder bump electrode is formed by a ball bonding method.

[Explanation of symbols]

1 Metal Plate 2 Insulating Substrate 3 Metal Layer 4 Insulating Film 5 Opening 6 Solder Plating 7 Semiconductor Layer 8 Insulating Protective Film 9 Conductor Electrode 10 Solder Connection Metal Layer 11 Adsorption Tool 12 Vacuum Hole 13, 17, 19, 23 Solder Bump Electrode 14 Metal Protruding Electrode 15 Solder Plating in a Spherical Shape 65 Metal Mask 81 Capillary 83 Solder Wire Part 82 Solder Ball 100, 101 Electrode Forming Substrate 200 Semiconductor Substrate

Claims (1)

[Claims] 1. An electrode-forming substrate is produced by forming an insulating film that does not wet the solder on a metal plate that does not wet the solder, and then solder connection that wets the solder on the circuit substrate on which the circuit element is formed. The insulating film of the electrode forming substrate in the region corresponding to the metal layer for use is removed to form an opening where the metal layer under the insulating film, which is not wet by the solder, is exposed. The solder is supplied to the opening of the insulating film by electrolytic plating using a metal layer on the substrate where the solder is not wet as a common electrode to form solder plating on the opening, and then the solder of the substrate for electrode formation is formed. The circuit board and the electrode forming board are aligned so that the plating and the solder connecting metal layer of the circuit board are opposed to each other, and then at least one of the circuit board and the electrode forming board is made of the solder. Above melting point Heat causes melting the solder plating, is brought into contact with the solder plating in the solder connection metal layer, then by separated and the circuit board and the electrode forming substrate,
A method of forming a solder bump electrode, characterized in that the molten solder plating is transferred from a metal layer exposed to the opening of the electrode forming substrate where the solder is not wet to a solder connecting metal layer where the solder of the circuit substrate is wet. .