JPH09148333A - Semiconductor device and manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid causing troubles such as poor positioning of bumps being formed in transfer or plating steps, dispersion of bump heights, growth of voids or solder balls, peel of bumps and ununiformity of plated bumps with resist masks. SOLUTION: A semiconductor device has bumps 3 formed by transferring original bumps 11 formed on a bump base board 1 to metallized layers 21 for electrodes on a substrate 2. In position, the bumps 11 are made to have a diameter and pitch smaller than the gap between the adjacent layers 21 and pitch thereof, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bump for connecting a semiconductor chip and a substrate, and more particularly to a semiconductor device having a bump for mounting the semiconductor chip on the substrate by a flip chip connection method and a method for manufacturing the same.

Semiconductor devices and electronic components used in electronic equipment are provided with electrodes of various forms in order to be mounted on a circuit board or the like and electrically connected, and these electrodes are connected by various connecting means. Connected.

In recent years, in order to shorten the wiring length and operate electronic equipment at high speed, a means has been adopted in which protruding electrodes (hereinafter referred to as bumps) are directly bonded to each other without using wires. The typical joining method is the flip chip joining method. In joining by bump,
It is necessary to form a large number of fine bumps at a time, and how to efficiently form fine and uniform bumps with high reliability is an issue.

[0004]

2. Description of the Related Art FIG. 13 is a schematic process diagram of a bump forming method by a transfer method, FIG. 14 is a measured value of the height of a bump formed by a vapor deposition method, and FIG. 15 is a diagram for explaining void formation in the bump. Schematic diagram, FIG. 16 is a schematic diagram illustrating generation of a solder mass from a wraparound film, FIG. 17 is a schematic diagram illustrating separation of bumps by a vapor deposition method, and FIG. 18 is a schematic process of a conventional method for forming solder for bumps. FIG. 19 and FIG. 19 are photomicrographs after formation of the bump solder of the conventional example.

In the figure, 1 is a bump original plate, 2 is a substrate, 3 is a bump, 4 is a flux, 5 is a metal mask,
5a is a first mask, 5b is a second mask, 6 is a metal layer, 7 is a peripheral cover layer, 8 is a transfer bump, 21 is an electrode metallization layer, 22
Is an insulating film, 31 is a lump of solder, 51 is a stack, 91 is a semiconductor substrate, 92 is a metal electrode, 93 is an insulating film, 94 is a liquid resist, and 95 is a liquid resist.
Is a bump, 96 is a dry film, 97 is an opening, 98 is a void, and 99 is an uneven surface.

Although various methods have been proposed for forming bumps, in the case of solder bumps, vapor deposition is performed using a metal mask, or solder balls are filled and soldered in the openings of the mask. , Apply solder paste,
There are methods such as plating, but plating has an advantage that fine bumps can be formed in a short time.

Further, since it is not necessary to introduce a semiconductor chip on which a bump is to be provided or a circuit board on which the semiconductor chip is mounted into a processing tank such as a vapor deposition tank or a plating tank, a master plate such as silicon or glass is preliminarily prepared. A transfer method is often used in which bumps are provided on a semiconductor chip and the bumps are transferred to a semiconductor chip or a circuit board.

FIG. 13 is a schematic process diagram of a bump forming method by a transfer method. In order to form the bumps 3 on the substrate 2 on which semiconductor elements and the like are formed by the transfer method, first, so-called transfer bumps 11 for transfer are provided in advance on the original plate 1 for bumps such as silicon or glass. The transfer bump 11 is formed by various methods.

FIG. 13A is a schematic view of a method of forming the transfer bumps 11 by a so-called mask vapor deposition method, in which the bump original plate 1 is covered with a metal mask 5 made of, for example, Kovar to be vapor-deposited. For example, In solder is used as a vapor deposition source (not shown), solder is deposited on the surface of the bump original plate 1 to a predetermined thickness from an opening at a predetermined position of the metal mask 5, and the metal mask 5 is removed. The transfer bump 11 can be formed. When removing the metal mask 5, the metal mask 5 is treated so as not to get wet with solder so that the transfer bump 11 is not damaged.

Next, in FIG. 13B, a resist 8 is applied to the bump original plate 1 to open holes at predetermined positions, solder is deposited by plating, and the resist 8 is peeled off to transfer bumps 11 And

Next, in FIG. 13C, the bump original plate 1 is covered with a metal mask 5, the openings at predetermined positions are filled with the solder paste 9, and then the metal mask is removed to obtain transfer bumps 11. .

In FIG. 13D, the substrate 2 is provided with an electrode metallization layer 21 at a predetermined position which is previously aligned with the transfer bump 11. The electrode metallization layer 21 includes, for example, Ti, Cr, Pt, Ni, A
A thin film layer in which u, Cu, etc. are laminated is used. In this case, Ti and Cr are films for improving adhesion of the substrate 2, Pt and Ni for preventing diffusion of solder, and Au and Cu for improving solder wettability.

In FIG. 13 (E), a flux 4 is applied to the transfer bumps 11 as needed, and the transfer bumps 11 are provided on the substrate 2 on which the electrode metallization layer 21 is formed. The master plates 1 are stacked facing each other, and the transfer bumps 11 are brought into contact with the electrode metallized layer 21 and heated.
Then, the transfer bumps 11 are melted and transferred to the electrode metallization layer 21.

In FIG. 13 (F), the bump original plate 1 is separated from the substrate 2, and if necessary, flux cleaning is performed, so that the bump 3 can be formed on the substrate 2. In forming bumps by plating, a method of forming solder bumps on metal electrodes on a semiconductor substrate using a resist as a mask is often used.

FIG. 18 is an explanatory view of a conventional example of bump plating using a resist as a mask, showing a schematic process drawing. There are roughly two types of resists used in electrolytic plating. One is a normal liquid resist 94 shown in FIG.
The film thickness after patterning is several to several tens of μm, and a fine pattern of about several μm can be formed. The other is Figure 18.
The dry film 96 shown in (B) can form a relatively large pattern having a thickness of several tens of μm or more.

[0016]

In the formation of bumps by the transfer method as described above, various troublesome problems are caused when the number of electrodes led out is increased and the size of the bumps is reduced or the pitch between the bumps is reduced. Occurs.

(1) Problem: 1 (Alignment during bump transfer) In order to form bumps by transfer, it is necessary to align the metallization layer for electrodes and the transfer bumps so as to face each other. However, for example, the diameter is 200 μmφ,
When the bump size is as small as 500 μm,
Since this alignment is troublesome, it is desired to be able to align the bump transfer without the need for manual intervention.

(2) Problem: 2 (Variation of bump height) When performing flip-chip bonding, it is desired that the bump height be uniform. However, the height of the bump is
As can be seen from the actual measurement values shown in FIG. 14, it is unavoidable that variations occur, and abnormally high bumps indicated by hatched arrows and abnormally low bumps indicated by white arrows are formed. In the case of abnormally high bumps, if the number of bumps is small, bonding failure does not occur if pressure is applied and crushed during flip chip bonding. However, in the case of an abnormally low bump, it cannot be bonded to a low bump unless, for example, several thousand bumps are pressed and crushed, so it is considered to be a bonding failure.

Such a variation in the height of the bump is caused when the transfer bump is formed by mask vapor deposition.
This is due to the variation in the opening area of the metal mask. By the way, since the metal mask is opened by etching, the accuracy of the opening area is about ± 20%. On the other hand, the height of the bump depends on the volume of the bump. Therefore, -20%
The volume of the bump formed by the mask vapor deposition of the open hole is (1-0.2) ² = 0.64, which is 64% of the average bump. Assuming that the bump shape is a sphere, 0.64 ^1/3 = 0.8
6, that is, the bump height is -14% of the average height, and stable bonding is not possible.

(3) Problem: 3 (Generation of voids in bumps) When bumps are formed on a semiconductor chip, particularly an LSI chip by the bump transfer method, a bump other than an electrode metallization layer is usually provided on the chip. The part is covered with a polyimide insulating film. Therefore, the portion of the electrode metallization layer is lower than the area around the electrode.

In FIG. 15A, when the transfer bump 11 provided on the bump original plate (not shown) is aligned with the electrode metallization layer 21 on the substrate 2 and abutted against each other, the transfer bump 11
The peripheral edge of 11 rides on the insulating film 41 to form a gap 42. Also,
If there is a slight misalignment, the transfer bump 11 may straddle the electrode metallization layer 21 and the insulating film 41, and a gap 42 may be formed between the transfer bump 11 and the electrode metallization layer 21.
When the transfer is performed by heating in this state, as shown in FIG. 15 (B), the gap 42 sometimes remains in the bump 3 as a hollow void 43.

When the transfer bumps are formed by the mask vapor deposition method, the voids 43 may occur even when the electrode metallization layer 21 is not indented because of its low density. Since the flux is used during the transfer, the flux remains in the void without being cleaned, which causes corrosion.

As a method for preventing the formation of voids in the bump, a method of melting the bump in a vacuum and degassing is known. However, in the case of an LSI, for example, when the bumps formed on the electrodes are melted, the wiring is deteriorated due to the mutual diffusion of the bumps and the electrodes, and the fatigue life of the bumps is shortened. Therefore, it is not preferable to melt the bumps once formed to remove the voids.

Further, the electrode diameter is 100 μm, and the joint height is 80 μm.
In the flip-chip joint, the solder joint with a void of 40 μmφ broke at 500 cycles in the thermal cycle test from −55 ° C to 125 ° C.
The solder joints with voids had fatigue life of 800 cycles or more. That is, a void having a size equal to or larger than half the electrode diameter or the joint height may significantly reduce the fatigue life of the solder joint.

(4) Problem: 4 (Generation of solder balls) When the transfer bumps are formed by a mask vapor deposition method using a metal mask on the bump original plate for forming the transfer bumps, the transfer bumps are superposed on the bump original plate. It often happens that bump material such as solder wraps around the gap between the mask and the mask, and a protruding film is formed in a portion other than the opening of the mask.

As shown in FIG. 16A, the transfer bumps
The wrap-around film 32 is formed so that the skirt extends outside the region of 11. As shown in FIG. 16 (B), this wrap-around film 32 often melts into small spherical solder, so-called solder ball 33, when heated. Therefore, when the bumps are transferred, if they are superposed on the substrate and heated, they are melted and solder lumps 31 called solder balls are scattered in the gaps between the bumps 3.

In order to prevent the formation of such solder balls, a method of removing the wrap-around film itself has been proposed. For example, in Japanese Patent Laid-Open No. 63-261857, transfer bumps are formed on a bump original plate. A method has been proposed in which a region other than the region is covered with a photosensitive polyimide film, a bump material is vapor-deposited with a mask, and then the polyimide film is wrapped around and dissolved and removed.

However, this method cannot be applied, for example, when polyimide is used for the insulating film on the surface of the semiconductor chip. There is also a method of using a photoresist film instead of polyimide, but it has a problem in heat resistance during vapor deposition or transfer.

Since the solder balls may be scattered between the bumps and cause a short circuit, the solder balls formed after the transfer are removed, and at the same time, the solder balls come around from the openings of the mask when the transfer bumps are formed. There is also a need for a solution that removes the wraparound film before the transfer process.

(5) Problem: 5 (Peeling off bumps by mask vapor deposition method) By the way, when forming bumps by mask vapor deposition method using a metal mask, the bump material adheres to the side wall of the opening of the metal mask, When the mask is peeled off, the bumps and transfer bumps are also peeled off, which is a problem.

In order to reduce this problem, for example,
Japanese Patent Laid-Open No. 63-261857 proposes a method in which a photosensitive polyimide layer is provided in a region other than the bump formation region, a bump material is vapor-deposited, and then the polyimide layer is dissolved with a solvent.
However, this method cannot be applied to a semiconductor chip or the like using polyimide as an insulating layer.

Further, Japanese Patent Laid-Open No. 5235003 proposes a method in which the inner wall of the opening of the metal mask is covered with a film made of a material having a good releasability for the solder. But in this case,
Bump material isolated from the sidewalls of the openings remains around the bumps, causing short circuits between adjacent bumps and solder balls.

Further, the diameters of the openings are made different between the front and back sides of the metal mask, that is, the openings are inversely tapered so that the sidewalls of the openings are shaded from the evaporation source so that the solder material does not adhere to the sidewalls of the openings. There is a way. FIG. 17 (A) shows an ideal form in which the side wall 52 of the opening 51 of the metal mask 5 has a reverse taper.

By the way, since the holes of the metal mask are manufactured by chemical etching, and the thickness of the metal mask is several tens of μm and the depth is large with respect to the diameter of the holes 51, the accuracy can be improved without overetching. It is difficult to drill well. By the way, if you do over-etching, you can see Fig. 17 (B).
As shown in, the side wall 52 of the opening 51 has a curved shape. Then, when the skirts of the bumps 3 and the transfer bumps 11 overlap the skirts of the side wall 52 at the back of the opening 51, the bumps formed when the metal mask 5 is peeled off as shown in FIG. 17C. 3 and the transfer bump 11 are peeled off.

In addition, in the method of forming solder bumps by plating, when plating is performed by using a liquid resist thinner than a dry film as a mask, FIG.
As shown in, a mushroom-shaped bump 95a is formed on the metal electrode 92 and extends over the insulating film.
The plated surface area of a continues to increase. Therefore, it is difficult to plate at a constant current density. Also, bump 95
The narrower the pitch between a, the easier it is for a short circuit. Further, the variation in the height of the final bump 95a also becomes large.

However, since the plating is performed with a diameter larger than the electrode diameter, a bump having a large volume can be formed. The bump 95 with a large volume is high when melted.
Becomes It is generally known that a flip chip joint having a high joint height has a long fatigue life, which is advantageous in this respect.

On the other hand, when plating is performed using a dry film thicker than the liquid resist, straight bumps 95b are formed as shown in FIG. 18 (B). Therefore, the surface area plated on the surface of the bump 95b does not change during plating, and the current density can be easily controlled. Further, the variation in height of the final bumps 95b is relatively small.

However, the volume of the bump 95b that can be formed is limited as compared with the bump 95a formed using the liquid resist 94. However, in principle, dry film 96 is used to form bumps 95 in a sawtooth shape, and bumps 95 with a large volume are formed.
However, it is difficult to peel the dry film 96 thereafter.

Even if the solder is simply plated with a large diameter, the entire surface of the opening 97 of the dry film 96 may not be filled with the plating as shown in FIG. There is a gap 98 in a part of
As shown in the micrograph magnified 0 times, which shows the shape of the bump plating after plating, the plating does not proceed uniformly, and the surface of the plated bump 95 may become an uneven surface 99.

In view of the above problems, the present invention provides a semiconductor device having a transfer bump that does not require complicated positioning, a method of manufacturing a semiconductor device including a transfer step in which bumps have a uniform height, and a bump Method for manufacturing a semiconductor device including a transfer step for reducing voids generated in a semiconductor, a method for manufacturing a semiconductor device including a transfer step for suppressing generation of solder balls, and a transfer step using a metal mask for obtaining bumps without peeling by a mask vapor deposition method It is an object of the present invention to provide a method for manufacturing a semiconductor device including the above, a semiconductor device formed by the manufacturing method, and a bump plating method for solving the defects of the liquid resist and the defects of the dry film.

[0041]

[Means for Solving the Problems]

(1) Regarding the above-mentioned problem 1, in the alignment at the time of bump transfer, as described in claim 1, a plurality of transfer bumps provided on the original plate for bumps are provided on the substrate. In a semiconductor device having bumps transferred to a plurality of electrode metallization layers, the transfer bumps have a diameter smaller than a gap between the electrode metallization layers adjacent to each other and a pitch of the electrode metallization layers. This is solved by a semiconductor device that is formed smaller than the pitch.

On the other hand, in the semiconductor device having such a structure, the transfer bumps, which are not transferred because they do not face the electrode metallization layer and thus become bumps, remain as harmful solder masses between the electrode metallization layers.

As described in claim 6, the solder mass is formed on the substrate by a transfer process of transferring the transfer bump on the bump original plate to the electrode metallization layer on the substrate. And a step of removing the solder lumps generated between the bumps and scattered together with the flux applied in the transfer step.

That is, for example, a bump diameter of 100 is provided on a substrate on which circuit components such as semiconductor elements are mounted.
When the transfer bumps provided on the bump master plate are all aligned and transferred to the electrode metallization layers of μmφ, pitch of 200 μm, and the number of dozens to thousands, the bump master plate is transparent. Even not easy.

Therefore, in the present invention, for example, the bump diameters of the transfer bumps formed on the bump original plate are 50 μmφ and the pitch is 100 μm, and the bump diameter and the pitch are small. The individual transfer bumps and the electrode metallization layer do not have to be aligned with each other.

Then, depending on the alignment state, for example, the number of transfer bumps that abut against the electrode metallization layer may be one or four. However, since the pitch of the transfer bumps is constant, the number of collisions does not vary and there is no problem.
In addition, when the transfer bumps that are not transferred because they do not face the electrode metallization layer are scattered between the electrode metallization layers as solder lumps, they are cleaned and removed together with the flux. Furthermore, since the portion of the substrate other than the electrode metallization layer is covered with an insulating layer or the like that does not wet the bump material, there is no short circuit between adjacent bumps.

(2) Next, as for the problem: the variation in the bump height of 2, the bumps are formed by vapor deposition through a plurality of openings of a metal mask placed on the original plate for bumps, as described in claim 7. In a method of manufacturing a semiconductor device including a transfer step of transferring a transfer bump to a substrate, the metal mask is inspected, and a metal mask including an opening area of 20% or less of a predetermined area is used as a defect and This is solved by a method for manufacturing a semiconductor device in which the transfer process is repeated a plurality of times.

That is, for example, the openings 10,0 of the metal mask
Assuming that one hole is mixed with 00 holes and -20% of holes are mixed,
It is assumed that a predetermined half amount of the transfer bump is transferred twice to form the bump. The volume of the bump formed by transferring the transfer bump deposited by -20% of the opening at the first transfer is
0.5 x (1-0.2) ² = 0.32. The volume of 0.32 is added to the bumps transferred for the second time, and the volume of 0.64 is 0.64.
The height is 0.86 at the 3rd root, and the height is poor.

However, the probability that a transfer bump formed by vapor deposition with a -20% opening of a metal mask is transferred to the same substrate twice is (1 / 10,000) ² , which is almost zero.
In other words, even if the transfer bump formed with -20% opening is transferred at the first time, the transfer bump formed with the predetermined opening is transferred at the second time and the volume becomes 0.32 + 0.50 = 0.82. If so, the height will be 0.94 from the cube root of 0.82, which is not a malfunction.

Thus, taking a semiconductor device having 3,000 terminals as an example, the probability of causing a height defect is about 1 in about 30,000 devices, which is remarkably reduced as compared with the prior art. Furthermore, transfer a predetermined 1/3 amount of transfer bumps three times,
If you transfer a predetermined 1/4 amount of transfer bumps four times,
Although the transfer process is increased, the probability of occurrence of bump height defects can be further reduced.

In the case of bumps whose height is higher than a predetermined value, the electrodes facing the high bumps are first struck and crushed during flip chip bonding. However, as can be seen from the measurement example shown in FIG. 9, the number of bumps exceeding the predetermined height is not so large. Therefore, it is not necessary to consider a bump whose height is higher than a predetermined value.

The inspection of the opening diameter of the metal mask requires a great number of man-hours such as visual appearance inspection. However, if a plurality of transfer steps according to the present invention are performed, the presence or absence of the opening diameter of -20% or less can be checked. In addition, the number of metal mask inspection steps can be significantly reduced.

(3) Next, as to the problem: the generation of voids in the bumps, as described in claim 8, in the metallization layers for electrodes formed in the insulating layer provided on the substrate. In a method of manufacturing a semiconductor device including a transfer step of transferring a transfer bump provided on a bump original plate, a step of providing a metal layer so as to extend over the electrode metallization layer and the insulating layer, and the metal The layer is wet and diffuses to the transfer bump, and the transfer step is solved by a method of manufacturing a semiconductor device including a step of aligning the transfer bump with the metal layer.

That is, one of the causes of the voids in the bumps is that air is trapped as a result of the abutment of the transfer bumps so as to cover the electrode metallization layer which is recessed from the surroundings. Becomes

Therefore, in the present invention, a metal layer made of a metal material that is well wetted by the solder forming the bump and diffuses into the solder is arranged to straddle the electrode metallization layer of the substrate on which the bump is formed. To be installed. Then, the transfer bump is aligned with the metal layer and transferred.

Then, in the transfer bumps melted on the electrode metallization layer and the metal layer, when the metal layer diffuses into the transfer bumps, the metal layer disappears and the transfer bumps are metalized for the electrode. It is possible to prevent voids from being generated in the bumps formed by being transferred to the layer and transferred.

If there is a risk of voids in the form of open pores due to poor solder wetting of the electrode metallization layer, use the multiple transfer steps according to the present invention described in (2) together. Can be prevented.

(4) Next, as for the problem: the generation of the solder balls of 4, as described in claim 9, 10 or 11, transfer bumps formed on the original plate for bumps by the vapor deposition process are transferred onto the substrate. In a method of manufacturing a semiconductor device including a transfer step of transferring to an electrode metallization layer provided on a substrate to form bumps on the substrate, a peripheral surface of the transfer bumps that is not wet is covered around the transfer bump formation region. A method of manufacturing a semiconductor device, comprising: a step of providing a layer; and a step of heating the transfer bump to melt the transfer bump after the vapor deposition step is completed, and then removing the surrounding layer, or provided on a substrate. In a method for manufacturing a semiconductor device, which includes a transfer step of transferring a transfer bump provided on a bump original plate to the electrode metallized layer to form a bump on the substrate, a metallized layer for an electrode is provided around the electrode metallized layer. This is solved by a method of manufacturing a semiconductor device, which includes a step of providing a non-wetting peripheral cover layer on the transfer bump and a step of removing the peripheral cover layer after the transfer step.

Here, a metal layer that can be removed by etching differently from the bumps or a resin layer that can be dissolved and removed by a solvent is used as the surrounding layer. When the transfer bumps are formed on the original plate for bumps by the mask vapor deposition method, the solder material that wraps around the original plate for bumps from the holes of the metal mask is used when the transfer bumps are transferred to the metallization layer for electrodes. Remains as solder balls around the layers other than the layers.

Therefore, in the present invention, first, a peripheral covering layer which is not wet with the transfer bump material is provided in advance around the region where the transfer bumps are formed on the original plate for bumps, and then vapor deposition is performed to form a wrap-around film. I try to receive it on the cover layer. After the vapor deposition is completed, when the original plate for bumps is heated to melt the transfer bumps, the wrap-around film becomes fine solder balls and is generated on the peripheral cover layer. Therefore, in the case of a metallic surrounding layer, the surrounding layer is etched by an etching solution that can be etched differently from the bump material, and in the case of a resin surrounding layer, a solvent is used. The solder balls generated from the wraparound film are removed together.

Alternatively, a surrounding layer made of a material that is not wet with the solder material is provided around the electrode metallization layer on the substrate. For example, when the metallized layer for electrodes is covered with a resin insulating film, a metal surrounding layer is used, and when the insulating film is not provided, a resin surrounding layer is also used. I have to. Then, during the transfer step of transferring the transfer bumps to the electrode metallization layer, the solder balls generated are received on the peripheral cover layer, and after the transfer step,
The surrounding layer is etched or melted so that the surrounding layer is removed together with the solder balls.

In this way, when the transfer bumps are formed using the metal mask, a defect due to the wrap-around film formed around the transfer bumps, that is, the solder balls generated after the transfer process can be removed. You can As a result, it is possible to reduce defects such as short circuits between adjacent bumps caused by the solder balls.

(5) Problem: As to the peeling of the bumps by the mask vapor deposition method of 5, as described in claim 12 or 14, the bumps are provided on the substrate through the holes of the metal masks placed on the substrate. In the method of manufacturing a semiconductor device, including the step of depositing bumps on a metallized layer for electrodes, the metal mask comprises an overlapping body of a plurality of metal masks having openings having different sizes, and the openings are formed on the substrate. A method of manufacturing the semiconductor devices that are arranged so as to spread toward each other,
Alternatively, in a method of manufacturing a semiconductor device, which includes a step of transferring a transfer bump deposited through an opening of a metal mask overlaid on a bump original plate to an electrode metallization layer on a substrate, the metal mask has a size This is solved by a method of manufacturing a semiconductor device, which comprises a plurality of metal mask overlapping bodies having different openings, and the openings are overlapped so as to spread toward the bump original plate.

If the openings of the metal mask are formed in a reverse taper shape, the transfer bumps may be separated when the mask is separated from the bump original plate after vapor deposition to form the transfer bumps. Although it is known to prevent this, it is not easy to taper the sidewall of the aperture.

Therefore, in the present invention, a plurality of metal masks having openings having different dimensions are overlapped with each other, and the side walls of the openings are expanded stepwise. Then, the side of the opening that contacts the bump original plate is made larger.

Then, since the side wall of the opening of the metal mask escapes in the direction of expansion, it is possible to prevent the bump material from adhering to the side wall of the opening even if the bump material goes around by vapor deposition of the mask. As a result, when the mask is peeled from the substrate on which bumps are to be formed or the original plate for bumps, it is possible to prevent the formed bumps and transfer bumps from being peeled together. The wrap-around film that wraps around the opening of the mask in this way causes the generation of solder balls, but the solder balls can be removed by the solution according to the present invention described in (4).

Next, a means for solving the problems in the bump forming method by plating using the resist as a mask will be described. FIG. 8 is a schematic process drawing of the bump solder forming method of the present invention.

In the figure, 61 is a semiconductor substrate, 62 is a metal electrode, 63 is an insulating film, 64 is a metal film or particles, 65 is a dry film or liquid resist, 66 is an opening, 67 is solder, 68 is a solder bump. Is.

As a means for solving this problem, as shown in FIG. 8, a dry film or liquid resist 65 is patterned and plated with a diameter larger than the electrode diameter of the metal electrode 62 formed on the semiconductor substrate 61. . The solder bump 68 formed from the straight-shaped solder 67 does not cause the problem of the conventional liquid resist. Moreover, since the diameter to be plated is large, the desired volume of solder 67 can be plated in a short time. Further, when the solder 67 is heated and melted after plating with a large diameter, the insulating film 63 and the solder 67 do not get wet, so the solder 67 is repelled from the insulating film 63, integrated on the metal electrode 62, and It becomes possible to form high solder bumps 68.

However, even if the solder is simply plated with a large diameter, the entire surface of the opening 97 of the dry film or the liquid resist 94 may not be filled with the solder as described with reference to FIG. The height and shape of the solder bumps 95 are not uniform.

Therefore, using an ordinary sputtering device,
When the surface of the insulating film 63 on the semiconductor substrate 61 is reverse-sputtered in advance, the surface of the metal electrode 62 is naturally also reverse-sputtered to deposit a metal film or metal particles 64 on the insulating film 63, which becomes a conductive film or a nucleus. It was revealed that the plating progressed and the solder 67 grew laterally.

The present invention makes use of this feature and is shown in FIG.
When the surface of the insulating film 63 shown in FIG. 5 and the surface of the metal electrode 62 are simultaneously reverse-sputtered, a metal film or metal particles are thinly deposited on the insulating film 63, as shown in FIG. Then, FIG. 8 (C)
As shown in FIG. 8, when a dry film or a liquid resist 65 is applied and the openings 66 in a range larger than the metal electrode 62 are patterned, the solder 67 is first formed into a dry film during solder plating as shown in FIG. 8D. The opening 66 of the opening 65 extends over the surface of the insulating film 63. Then, the entire opening 66 of the dry film 65 is plated with the solder 67. By doing so, the entire opening 66 of the dry film 65 can be uniformly filled with the solder 67, and after the dry film 65 is removed, heat treatment is performed to form a solder bump 68 having a large volume as shown in FIG. 8E. Can be formed.

As described above, the purpose of forming bumps by plating using the resist of the present invention as a mask is to withstand the melting point of solder on the semiconductor substrate 61 on which the metal electrodes 62 are formed, as shown in FIG. 8A. A step of covering the obtained insulating film 63 except on the metal electrode 62, and then, as shown in FIG. 8B, the surface of the substrate including the metal electrode 62 is reverse-sputtered to form the insulating film 63. A step of depositing a metal film or metal particles 64 thereon, and then, as shown in FIG. 8C, a dry film or a liquid resist 65 is coated on the insulating film 63, exposed and developed, and A step of forming an opening portion 66 including the metal electrode 62 and having a diameter larger than at least the metal electrode 62, and then, FIG.
8A, a step of coating (plating) the solder 67 in the opening 66, and then, as shown in FIG. 8E, the solder 67 is heated and melted to form spherical solder bumps 68. It is achieved by including the step of

[0074]

1 is an explanatory view of a first embodiment of the present invention, FIG. 2 is an explanatory view of a second embodiment of the present invention, and FIG. 3 is an explanation of a third embodiment of the present invention. FIG. 4, FIG. 4 is an explanatory view of a fourth embodiment of the present invention, FIG. 5 is an explanatory view of a fifth embodiment of the present invention,
6 is an explanatory view of a sixth embodiment of the present invention, FIG. 7 is an explanatory view of a seventh embodiment of the present invention, and FIGS. 9 to 10 are schematic explanatory views in order of steps of an eighth embodiment of the present invention. FIG. 11 is a photomicrograph of the bump solder of the present invention after formation, and FIG. 12 is a photomicrograph of the solder bump of the present invention after melting after completion of the solder bump.

In the figure, 1 is a bump original plate, 11 is a transfer bump, 2 is a substrate, 21 is an electrode metallization layer, 22 is an insulating film, 3 is a bump, 31 is a solder block, 32 is a wraparound film, 4
Is flux, 5 is a metal mask, 5a is a first mask, 5b
Is a second mask, 51 is a stack, 6 is a metal layer, 7 is a surrounding layer,
71 is a Si wafer, 72 is a Ti film, 73 is a Ni film, 74 is a metal electrode, 75 is a polyimide film, 76 is a through hole, 77 is a metal film or metal particles, 78 is a dry film, 79 is an opening,
80 is a solder and 81 is a solder bump.

First Embodiment: 1 (related to claims 1 to 6) In FIG. 1 (A), a substrate 2 is made of a 10 mm □ Si chip, and the thickness of Au / Ni is 0.1 / 0.5 μm.
Then, a 200 μmφ electrode metallization layer 21 is provided in a matrix pattern at a pitch of 500 μm, and Pb-63 wt% Sn solder is deposited thereon. The bump original plate 1 is made of a glass substrate, and Pb-63 wt% Sn solder is vapor-deposited on the bump original plate 1 using a metal mask (not shown) to have a diameter of 50 μm.
A transfer bump 11 having a height of φ and a height of 50 μm is formed.

In FIG. 1 (B), the flux 4 was applied to the transfer bumps 11 and the substrate 2 was not superposed on the substrate 2 but was randomly superposed and heated to 220 ° C. In FIG. 1 (C), the transfer bumps 11 abutted against the electrode metallization layer 21 were transferred to form the bumps 3 on the substrate 2. In addition, the transfer bumps 11 that did not collide with the electrode metallization layer 21 are the bumps 3
Remains as a solder mass 31 in the gap. When the bump original plate 1 is separated from the substrate 2 and the flux 4 is washed, the solder mass 31 is cleaned and removed together with the flux 4 as shown in FIG. Good bumps 3 could be formed.

First Embodiment: 2 (related to claims 1 to 6) In FIG. 1 (A), an alumina ceramic circuit board used for a hybrid IC is used as the board 2 and the thickness of Au / Ni is 0.1 / each. An electrode metallization layer 21 of 0.5 μm and 400 μmφ is provided in a matrix pattern at a pitch of 800 μm, and In-48 wt% Sn solder is deposited thereon. In-48 wt% Sn solder paste was screen-printed on the original plate 1 for bumps on the glass substrate to a diameter of 100 μm.
The φ transfer bumps 11 are formed at a pitch of 200 μm.

In FIG. 1 (B), the flux 4 was applied to the transfer bumps 11 and they were superposed on the substrate 2 without being aligned, and heated to 150 ° C. In FIG. 1C, the transfer bumps 11 abutted against the electrode metallization layer 21 were transferred to form the bumps 3 on the substrate 2. When the bump original plate 1 is separated from the substrate 2 and the flux 4 is washed,
The bumps 3 were formed as shown in FIG.

First Embodiment: 3 (Related to Claims 1 to 6) In FIG. 1 (A), an alumina ceramic circuit substrate used for a hybrid IC is used as the substrate 2 and the thickness of Au / Ni is 0.1 /. Electrode metallization layers 21 of 0.5 μm and 200 μmφ are provided in a matrix at a pitch of 500 μm, and In solder is deposited thereon. On the bump original plate 1 made of a polyimide film, In solder is vapor-deposited through a metal mask 5 to form transfer bumps 11 having a diameter of 50 μmφ and a height of 50 μm at a pitch of 100 μm.

In FIG. 1B, the flux 4 was applied to the transfer bumps 11 and abutted against the substrate 2 without aligning them, and thermocompression bonded at 150 ° C. and 5 Kgf. Then, in FIG. 1 (C), when heated to 220 ° C., the transfer bumps 11 abutted against the electrode metallization layer 21 were transferred onto the substrate 2. When the original plate 1 for bumps was separated from the substrate 2 and the flux 4 was washed, the bumps 3 were formed as shown in FIG. 1 (D).

In this case, the bump material is Pb-63 wt% Sn.
Although solder, In-48 wt% Sn solder paste, or the like was used, a solder containing Bi, Ga, Ge, or Sb may also be used in addition to the above. Further, various modifications can be made to the bump original plate for forming the transfer bumps and the electrode metallized layer.

Second embodiment: 1 (claims 7, 15, 16, 17)
Or 18) In FIG. 2 (A), using a metal mask (not shown) in which the diameter of the opening is 130 μmφ on the front side and 170 μmφ on the back side and the side wall angle is about 100 °, Pb is deposited on the Si original plate 1 for bumps.
-5 wt% Sn solder was vapor-deposited to form the transfer bumps 11 having a height of 30 μm. Here, the transfer bumps 11 at the right end are typically lower in height than the other bumps 3.

In FIG. 2B, the transfer bump 11
Flux 4 is applied to and is aligned with the Ni electrode metallization layer 21 on the substrate 2 on which the Si element is formed,
After transferring by heating at 360 ° C., the bump original plate 1 was separated from the substrate 2 and the flux 4 was washed, as shown in FIG. 2C, to form the bump 3 on the substrate 2. .

Further, as shown in FIG. 2D, transfer bumps 11 are formed on the bump original plate 1 as in FIG.
As shown in (E), the flux 4 is applied to the transfer bump 11.
The bumps 3 formed by the first transfer of the substrate 2 by applying
Then, the flux 4 was washed after the transfer was performed by heating to 350 ° C. As shown in FIG. 2F, the bumps 3 transferred twice were formed on the substrate 2.

When the heights of all the bumps 3 on the substrate 2 made of the Si element thus formed were measured, the average bump height was 84.3 μm, the minimum height was 79.2 μm, and the maximum bump height. Was 87.9 μm. This Si element and Al
F-chip bonding with N substrate without flux, C
A PU module was produced. When the electrical reliability of the joint was examined, no defects were found.

Second embodiment: 2 (claims 7, 15, 16, 17)
Or 18) The bumps were formed by using the various solders as samples in the same double transfer method as in the second embodiment. Table 1 shows the heating conditions of each sample.

[0088]

[Table 1]

Table 2 shows the measurement results of the height of the bumps thus formed from the respective samples.

[0090]

[Table 2]

As can be seen from Table 2, it is possible to prevent the unevenness of the bump height, especially the minimum value, from being abnormally reduced by the double transfer. As a result, when the Si elements to which the respective bumps were transferred were flip-chip bonded to the AlN substrate and the reliability was examined in the same manner as in Example 1, there were no bonding defects.

Second embodiment: 3 (claims 7, 15, 16, 17)
Or 18) The diameter of the openings is 150 μmφ on the front side, 180 μmφ on the back side, the angle of the side wall is about 100 °, the average diameter of the openings is 150 μmφ, and the height average is 150 μmφ. The following calculation was performed to form a bump having a diameter of 85 μm and a minimum height of 75 μm.

75/85 = 0.88 (0.88) ³ = 0.69 0.69 ^1/2 = 0.82 Using this metal mask, Pb-5 wt% Sn solder was vapor-deposited on the glass bump original plate, and then the metal mask was peeled off to transfer. Bumps were formed. After applying the flux to the transfer bump, align it with the Ni electrode metallization layer on the Si element, and heat it to 360 ° C to remove Pb-
Transfer the 5wt% Sn solder transfer bumps from the bump original plate to S
It was transferred onto the electrode metallization layer of the i element. After repeating this transfer process twice, a flux was applied to remove the oxide film on the bump surface, heated to 350 ° C. and cooled, and then the flux was removed.

When the heights of all the bumps on the Si element were measured, the average bump height was 84.9 μm, the minimum bump height was 78.3 μm, and the maximum bump height was 90.1 μm. S
The i element was flip-chip bonded to the AlN substrate without flux to prepare a CPU module. When the electrical reliability of the joint was examined, no defects were found.

In the second embodiment, the bump height variation correction is exemplified by two transfer steps, but the number of transfers is not limited to two, and a metal mask, transfer bumps, transfer formation are performed. Various modifications are possible depending on dimensional conditions such as bumps to be formed and the type of solder.

Third Embodiment: 1 (related to claim 8, 15, 17 or 18) In FIG. 3 (A), a substrate 2 is a Si substrate provided with a semiconductor element, and a Ni electrode metallization layer is formed. 21 is formed, and the periphery of the electrode metallization layer 21 is covered with a polyimide insulating film 22. Then, the Au film having a thickness of 0.5 μm is formed across the metallized layer for electrode 21 and the insulating film 22.
Metal layer 6 is provided.

The transfer bumps 11 were formed of Pb-5 wt% S by using a metal mask on a Si bump original plate (not shown).
It is formed by vapor deposition of n solder. Transfer bump
After applying the flux 4 to 11, the metal layer 6 is aligned by aiming at the side of the insulating film 22 as shown in FIG.
The bumps 11 for transfer made of Pb-5 wt% Sn solder were transferred to the metal layer 6 of the substrate 2 by heating to 360 ° C. Transfer bump
In the Pb-5 wt% Sn solder of No. 11, Au of the metal layer 6 was diffused and disappeared, and the Pb-5 wt% Sn solder was wet with Ni of the metallized layer for electrode 21 and moved as shown by the arrow. Then, as shown in FIG.
The bumps 3 made of b-5 wt% Sn solder were formed.

The bumps 3 thus formed on the substrate 2
After washing a flux (not shown) and observing it with a transmission X-ray, no void was found in the bump 3. To remove the oxide film on the surface of the bump 3, flux was applied again, heated to 350 ° C., cooled, and washed with flux. The substrate 2 on which the bumps 3 are formed is
Flip chip bonding with 1N substrate without flux, C
As a PU module, a reliability test was conducted, but there were no defects.

Third Example: 2 (related to claim 8, 15, 17 or 18) Bump formation was performed by using various solders as samples in the same transfer method as in the third example: 1. The heating conditions of each sample are the same as those shown in Table 1 of the second embodiment: 2.

The bumps formed under the respective conditions were observed by transmission X-ray, and no void was found in the bumps. Further, the substrate on which the respective bumps were formed was flip-chip bonded to the AlN substrate without flux to prepare a CPU module, and a corrosion test was conducted, but there was no problem.

In this case, the bump material is Pb-5 wt% Sn.
Although solder or In solder was used, in addition to that, for example, B
A solder containing i, Ga, Ge, Sb, or the like can also be used. In addition to Si, glass, ceramics, or a resin film having high heat resistance such as polyimide can be used in addition to Si for the original plate for bumps on which transfer bumps are formed. Further, the electrode metallization layer for forming the bumps may have Au or T in addition to Ni depending on the type of the bump material.
Multi-layer thin films of i, Cu, Cr, etc. can also be used.

Fourth Embodiment (Related to Claim 9, 11, 15, 17 or 18) In FIG. 4 (A), the substrate 2 is made of a Si substrate provided with a semiconductor element, and the electrode metallization layer 21 is made of Au. It consists of electrodes. Around the electrode metallization layer 21, a film thickness of 0.1
A peripheral covering layer 7 of Al having a thickness of μm was provided by vapor deposition. The diameter of the opening is 130 μmφ on the front side and 170 μmφ on the back side, and the side wall angle is
Using a metal mask (not shown) of 100 °, Pb-5 wt% Sn solder is vapor-deposited on the Si bump original plate 1.
A transfer bump 11 having a height of 30 μm was formed. However, at the skirt of the transfer bump 11, a wrap-around film 32 that has entered the gap between the bump original plate 1 and the metal mask 5 (not shown) is generally unavoidable.

In FIG. 4B, the transfer bump 11
4 is coated with the flux 4, aligned with the Au electrode metallization layer 21 on the substrate 2, transferred by heating to 360 ° C., the bump original plate 1 is separated, and the flux 4 is washed. The bumps 3 were formed on the substrate 2 as shown in FIG. At the same time, the wrap-around film 32 was scattered around the bumps 3, and spherical solder lumps 31 were generated as so-called solder balls.

Then, the substrate 2 is distilled water: 90 ml, hydrochloric acid: 15
ml, hydrofluoric acid: dip it in an etching solution consisting of 10 ml, and
When 1 l of the peripheral covering layer 7 was dissolved and removed, as shown in FIG. 4 (D), the solder mass 31 could also be removed at the same time, and good bumps 3 could be transferred and formed on the substrate 2.

In this case, the bump material is Pb-5 wt% Sn.
Although solder was used, other than that, for example, In, Ga, G
A solder containing e, Sb or the like can also be used. In addition to Si, glass, ceramics, or a resin film having high heat resistance such as polyimide can be used in addition to Si for the original plate for bumps on which transfer bumps are formed. Further, a multilayer thin film such as Ni / Ti or Cu / Cr can be used for the electrode metallization layer for forming the bump depending on the type of the bump material. Further, the size of the opening of the metal mask can be variously modified.

The surrounding layer which is not wet with the bump forming material is made of Al, for example, when a resin film such as polyimide is deposited as an insulating film on the substrate 2 provided with the semiconductor element. An effective metal film is effective. However, when a resin film such as polyimide is not deposited, for example,
A resin film having heat resistance and soluble in a solvent such as polyimide can also be used. Further, when the solder mass is fine, it is possible to immerse it in a mixed acid of nitric acid and acetic acid to preserve the bump formed by transfer, and to dissolve and remove only the solder mass, and various modifications are possible. .

Fifth Embodiment (Claim 10, 11, 15, 17 or 18) In FIG. 5 (A), an Al film having a film thickness of 0.1 μm is formed in a region other than the region of the transfer bump 11 of the glass bump original plate 1. The surrounding layer 7 was provided by vapor deposition. And the diameter of the aperture is 130μ on the surface.
Using a metal mask 5 with mφ, back side 170 μmφ and side wall angle of about 100 °, Pb is placed on the glass original plate 1 for bumps.
-5 wt% Sn solder was vapor-deposited to form transfer bumps 11 having a height of 30 μm.

As shown in FIG. 5B, this transfer bump 11 is a wrap-around film that enters the gap between the bump original plate 1 and the metal mask 5 which is generally inevitable in the skirt of the transfer bump 11. 32 was crawling out.

Next, when the bump original plate 1 on which the transfer bumps 11 are formed is heated at 320 ° C. in an N ₂ -H ₂ (4: 1) atmosphere, as shown in FIG. 5 (C). A part of the wrap-around film 32 is formed as a solder mass 31 on the surrounding layer 7.

Then, the original plate 1 for bumps is distilled water: 90 ml,
When the Al peripheral covering layer 7 was dissolved and removed by immersing it in an etching solution consisting of hydrochloric acid: 15 ml and hydrofluoric acid: 10 ml, FIG.
As shown in (D), the solder mass 31 can be removed at the same time,
Transfer bumps without wrap-around film 32 on bump original plate 1
11 could be formed.

The surrounding layer that does not get wet with the bump-forming material is A
In addition to the metal film such as l, a resin film having heat resistance and soluble in a solvent, such as polyimide, can be used. Further, when the solder lump is fine, the transfer bump can be preserved by immersing it in a mixed acid of nitric acid and acetic acid, and only the solder lump can be dissolved and removed. Further, although Pb-5 wt% Sn solder was used as the bump material, other solder, for example, containing In, Ga, Ge, Sb, or the like can also be used. In addition to glass, Si, ceramics, or a resin film having high heat resistance such as polyimide can be used in addition to glass for the original plate for bumps on which transfer bumps are formed. Further, the size of the opening of the metal mask can be variously modified.

Sixth Embodiment: 1 (related to claim 12, 13, 16 or 18) In FIG. 6, the metal mask 5 has an opening diameter of 140 mm.
The first mask 5a made of 42-alloy having a thickness of 50 μm and the second mask made of 42-alloy having a diameter of the aperture of 170 μm and a thickness of 50 μm.
An overlay 51 was used in which the mask 5b was superposed with the centers of the respective openings aligned. Substrate 2 has 100 μmφ A
A circuit board provided with a u / Ni / Ti electrode metallization layer 21 was used. In the vapor deposition device not shown, the second mask
5b and the first mask 5a were aligned in this order, and the stacking body 51 was fixed by a deposition jig using a magnet so that the openings were aligned with the electrode metallization layer 21 of the substrate 2.

Pb-5 wt% Sn solder was vapor-deposited to a thickness of 30 μm, the stack 51 was peeled from the substrate 2, and bumps 3 were formed. At this time, the solder material is applied to the stacking body 51, especially the second mask 5b.
No adhesion to the side wall of the bump was observed, and the bump 3 did not drop. Then, in order to remove the oxide film on the surface of the bump 3 and to shape the bump 3, a flux is applied to the bump 3 to obtain the melting point of the Pb-5 wt% Sn solder.
It was possible to form good bumps 3 on the substrate 2 by heating to a temperature higher than ° C to melt and cooling and then removing the flux by washing.

Thus, the Pb-5 wt% Sn solder van
The substrate 2 on which the cap 3 is formed is, for example, 100 μmφ Au.
/ Ni / Ti metallized electrode on Si chip
On the substrate 2 on which the flux 3 is applied and the bumps 3 are formed
Align. And N _TwoGas atmosphere reflow furnace
If it is heated to 350 ° C inside, a flip-chip bonded structure will be formed.
Can be achieved.

Sixth Embodiment: 2 (related to claim 12, 13, 16 or 18) In FIG. 6, 42 having an aperture diameter of 140 μm and a thickness of 50 μm.
-The first mask 5a made of alloy and the diameter of the opening is 170 μm,
A second mask 5b made of 42-alloy having a thickness of 50 μm is superposed with the centers of the openings aligned, and the stacking body 51 adhered with an epoxy resin is used as the metal mask 5. Substrate 2 has 1
A Si chip provided with an Au / Pt / Ti electrode metallization layer 21 of 00 μmφ was used. In the vapor deposition device (not shown), the stacking member 51 aligned so that the second mask 5b abuts on the substrate 2 was fixed by a vapor deposition jig using a magnet (not shown).

In solder was vapor-deposited with a thickness of 30 μm and placed on the stacking member 51.
Was peeled from the substrate 2 to form bumps 3. At that time, the solder material was not observed to adhere to the side wall of the second mask 5b of the stacking body 51, and the bump 3 did not drop. Then, in order to remove the oxide film on the surface of the bumps 3 and to shape the bumps 3, flux is applied to the bumps 3 to remove the oxide film.
It was heated to 215 ° C, which is higher than the melting point of the n solder, to be melted. After cooling, the flux was washed and removed, and good In bumps 3 could be formed on the substrate 2.

The substrate 2 on which the In solder bumps 3 are formed is, for example, 100 μmφ Au / Pt / Ti.
In the same manner, the bumps may be aligned with the circuit board on which the In bumps are provided on the metallized electrodes, and a flip-chip bonded body may be formed by the VPS method in fluorocarbon vapor at 260 ° C without using flux. it can.

In this case, the bump material is made of Pb-5 wt% Sn.
Although solder or In solder was used, in addition to that, for example, B
A solder containing i, Ga, Ge, Sb, or the like can also be used. In addition to Si and glass, a resin film having high heat resistance such as ceramic or polyimide can be used for the original plate for bumps on which transfer bumps are formed. Further, a multilayer thin film such as Ni / Ti or Cu / Cr can be used for the electrode metallization layer for forming the bump depending on the type of the bump material. Further, the size of the opening of the metal mask can be variously modified.

Seventh Embodiment: 1 (Claims 14, 15, 16, 17
Or 18) In FIG. 7A, the metal mask 5 has a 42-alloy first mask 5a with an opening diameter of 140 μm and a thickness of 50 μm.
A second mask 5b made of 42-alloy having an opening diameter of 170 μm and a thickness of 50 μm was superposed with the centers of the openings aligned with each other. In a vapor deposition device (not shown), a stacking body 51 in which the second mask 5b and the first mask 5a are aligned in this order is used for the vapor deposition jig 1 using a magnet (not shown) on the bump original plate 1 made of Si. Fixed in.

Pb-63% Sn solder was vapor-deposited to a thickness of 30 μm, and the stack 51 was peeled off from the bump original plate 1 to form transfer bumps 11. At that time, the solder material did not adhere to the side wall of the second mask 5b of the stacking body 51, and the transfer bump was formed.
A good transfer bump 11 was obtained without missing 11.

In FIG. 7B, the substrate 2 on which the transfer bumps 11 are to be transferred has a semiconductor element and Ni / T of 150 μmφ.
Using a Si substrate provided with the electrode metallization layer 21 of i,
The flux 4 is applied to the transfer bumps 11, and the bump original plate 1 and the substrate 2 are superposed so that the positions of the electrode metallization layers 21 are aligned with each other, as shown in FIG. 7C. The transfer bumps 11 were transferred onto the electrode metallization layer 21 by heating at 250 ° C. in a reflow furnace in an N ₂ gas atmosphere. After that, as shown in FIG. 7D, the original plate for bump 1 is peeled from the substrate 2, the oxide film on the surface of the bump 3 formed on the substrate 2 is removed, and the bump 3 is shaped. To do this, apply flux to the bumps 3 and Pb
It was melted by heating to 250 ° C, which is higher than the melting point of -63% Sn solder. After cooling, the flux is washed and removed,
Good bumps 3 could be formed on the substrate 2.

Thus, the substrate 2 on which the bumps 3 of Pb-63% Sn solder are formed is, for example, Ni / 100 μmφ.
The bump 3 is formed on the circuit board provided with the Ti metallized electrode.
The flip chip bonded body can be constructed by aligning the metallized electrodes with the metallized electrodes and heating them to 250 ° C. in a reflow furnace in an N ₂ gas atmosphere using flux to bond them.

Seventh Embodiment: 2 (Claims 14, 15, 16, 17
Or 18) In Figure 7 (A), the diameter of the aperture is 140μm and the thickness is 50μ.
m 42-alloy first mask 5a with an aperture diameter of 170
A second mask 5b made of 42-alloy having a thickness of 50 .mu.m and having a thickness of 50 .mu.m is superposed with the centers of the openings aligned with each other, and an overlay 51 adhered with an epoxy resin is used as the metal mask 5. In the vapor deposition device (not shown), the stacking body 51 aligned so that the second mask 5b contacts the glass bump original plate 1 was fixed by a vapor deposition jig using a magnet (not shown). .

In solder was vapor-deposited to a thickness of 30 μm and placed on the stacking member 51.
Was peeled from the bump original plate 1 to form transfer bumps 11. At this time, the solder material is applied to the stacking body 51, especially the second mask 5b.
Adhesion to the side wall of No. 2 was not seen, and the transfer bump 11 was not missing, and a good transfer bump 11 was obtained.

In FIG. 7B, the transfer bumps 11 are transferred by a substrate 2 made of Si provided with a semiconductor element and a Cu / Cr electrode metallization layer 21 of 150 μmφ, and a 100 μmφ not shown. The test was performed on each of the ceramic circuit boards provided with the Cu / Cr electrode metallization layer 21. That is, after applying the flux 4 to the transfer bumps 11, as shown in FIG. 7C, the bump original plate 1 and the substrate 2 are superposed so that the positions of the electrode metallization layers 21 are aligned with each other. The transfer bumps 11 were transferred onto the electrode metallization layer 21 by heating at 215 ° C. in a reflow furnace in an N ₂ gas atmosphere (not shown). Although not shown, transfer was performed on a circuit board under the same conditions.

After that, as shown in FIG. 7D, the bump original plate 1 is peeled off from the substrate 2, and the oxide film on the surface of the bump 3 formed on the substrate 2 is removed or the bump 3 is removed. Flux is applied to the bumps 3 in order to shape the
It was heated to 215 ° C, which is higher than the melting point of the n solder, to be melted. After cooling, the flux is washed and removed, and the substrate 2
It was possible to form a good bump 3 on the above. A circuit board (not shown) was processed under the same conditions to obtain good bumps 3.
Could be formed.

Thus, the substrate 2 on which the bumps 3 are formed and the circuit board are, for example, aligned by superimposing the respective bumps 3 on each other, and using a VPS method in a fluorocarbon vapor at 260 ° C. without using flux. A flip chip bonded body can be constructed.

In this case, the bump material is Pb-5 wt% Sn.
Although solder or In solder was used, in addition to that, for example, B
A solder containing i, Ga, Ge, Sb, or the like can also be used. In addition to Si and glass, a resin film having high heat resistance such as ceramic or polyimide can be used for the original plate for bumps on which transfer bumps are formed. Further, a multilayer thin film such as Ni / Ti or Cu / Cr can be used for the electrode metallization layer for forming the bump depending on the type of the bump material. Further, the size of the opening of the metal mask can be variously modified.

Next, an eighth embodiment of the present invention as to a bump forming method by plating using a resist as a mask will be described. First, a conventional method will be described for comparison.

As shown in FIG. 9B, a metal electrode 74 (1) for plating is formed on a 4-inch silicon (Si) wafer 71.
00 μmφ) is formed. This metal electrode 74 is shown in FIG.
As shown in, the titanium (Ti) film 72 and the nickel (Ni) film 73 are laminated to a thickness of 1,000 Å and 5,000 Å by the sputtering method, respectively. Then, as shown in FIG. 9D, a polyimide film having a thickness of 3 μm is formed except for the portion to be the metal electrode 74.
An insulating film is formed by covering with 75. On top of this, see Fig. 10 (F).
As shown in FIG. 10, a dry film 78 having a thickness of 50 μm is laminated, and as shown in FIG. 10G, openings 79 for plating are patterned with a pitch of 250 μm and 130 μmφ larger than the diameter of the metal electrodes 74.

Next, using a Ni film as a conductive film for plating, a lead (Pb) -tin (Sn) (5%) solder plating solution was used to perform electrolytic plating to a thickness of 35 μm. H)
Solder 80 is plated into opening 79 as shown in FIG.

After plating the solder 80, the dry film 78 is peeled off, and the bumps of the solder 80 formed on the metal electrodes 74 are observed. Then, as shown in the micrographs in FIGS. 18 (C) and 19, the 130 μmφ bumps 95 were formed, but it was observed that a part of the peripheral edge was not plated and was not filled with the opening 97 of the dry film 96. Was done. Also bump
The surface of 95 also became uneven in height, and uneven surface 99 was seen.

Next, an eighth embodiment of the present invention will be described with reference to FIGS.
Will be described with reference to the schematic cross-sectional views in the order of steps. As shown in FIG. 9A, in order to form a metal electrode 74 for plating on a 4-inch Si wafer 71, the Ti film 72 has a thickness of 1,000 Å and the Ni film 73 has a thickness of 5,000 Å by a sputtering method. 9B and patterned by photolithography as shown in FIG. 9B to form a metal electrode 74 of 100 μmφ.

Then, as shown in FIG. 9C, a polyimide film 75 having a thickness of 3 μm is coated as an insulating film capable of withstanding the melting point of the solder used for bump formation, and bumps are formed on the metal electrodes 74 by photolithography. In order to
Through holes 76 are opened as shown in FIG.

Thereafter, the surface of the polyimide film 75 is reverse-sputtered by the method of the present invention. For the reverse sputtering, a general sputtering apparatus is used. At the time of the reverse sputtering, a shield plate is provided in front of the target such as Ni, the Si wafer 71 is set on the wafer chuck facing the target, and argon (Ar) is used.
Gas is introduced and S is output at an output of 1 kW and a vacuum degree of 1 × 10 ^-1 Pa.
The metal electrode 74 on the surface of the i-wafer 71 is hit with Ar particles.

Then, as shown in FIG. 9E, the surface of the Ni film 73 of the metal electrode 74 is naturally reverse-sputtered, and a metal film or metal particles 77 are deposited on the entire polyimide film 75 on the periphery.

Then, as shown in FIG. 10F, 50 μm is formed on the entire surface of the Si wafer 71 covered with the polyimide film 75.
The dry film 78 with the thickness of
As shown in (3), a resist pattern for plating having a diameter of 130 μm is formed at a pitch of 250 μm to form openings 79. next,
Electrolytic plating is performed using a Pb-Sn (5%) solder plating solution to form the solder 80 in the opening 79.

After plating the solder 80, the dry film 78 is peeled off, and the solder 80 for bumps formed on the metal electrode 74 is removed.
As a result, as shown in the micrograph in FIG. 11, good solder bumps 81 having a diameter of 130 μm were formed.

Next, when the bumps of the solder 80 are heated at 350 ° C. for about 1 minute to melt the solder 80, as shown in the micrographs of FIG. 10 (I) and FIG. Solder 80 having a diameter of about 35 μm and a diameter of 130 μm was formed on spherical solder bump 81 having a diameter of about 70 μm after heating and melting. At this time, the thin metal film or metal particles 77 on the lower surface of the solder 80 is dissolved and absorbed by the solder bump 81.

Although the dry film 78 having a thickness of 50 μm is used in the embodiment of the present invention, the dry film 78 has a thickness of 2 μm.
0 μm is possible, in which case the bump height is about 15 μm, and after heating and melting, a spherical solder bump 81 of about 30 μm is formed, and the pitch of the solder bump 81 is 100 μm.
It is possible up to m.

When a finer solder bump 81 is required, for example, in the case of a fine pattern having an electrode diameter of about 10 μmφ, a liquid resist is used and the size is 20 μm or less, which is a size capable of flip chip bonding. The solder bump 81 can be obtained in a similar manner.

Further, the solder material is not limited to the embodiment of the present invention, and is Sn-based, silver (Ag) -based, antimony (Sb) -based, indium (In) -based, bismuth (B).
It goes without saying that it can be implemented with all solder materials such as i) type.

[0143]

As described above, according to the present invention,
In the bump formation by the transfer method, the problem 1 is the alignment when the fine bumps are transferred.
As described above, the diameter of the plurality of transfer bumps provided on the bump original plate for transferring to the plurality of electrode metallization layers provided on the substrate is equal to the gap between the adjacent electrode metallization layers. Since the pitch is smaller than the pitch and smaller than the pitch of the metallized layer for electrodes, it is possible to eliminate the need for alignment. Further, at this time, the solder lumps scattered between the bumps can be removed by washing together with the flux applied in the transfer step, as described in claim 6.

Next, as for the problem: the bump height variation of 2, as described in claim 7, the transfer formed by vapor deposition through a plurality of openings of the metal mask placed on the original plate for bumps. As for the variation of the bumps for use, the metal mask is inspected, and the metal mask including the opening area of 20% or less of the predetermined area is not used as a defect and
By repeating the transfer process multiple times, the bump height can be
The non-uniformity shown in 14 disappears.

Next, as to the problem: the generation of voids in bumps, as described in claim 8, a metal layer is provided so as to extend over the metallization layer for electrodes and the insulating layer. It is possible to prevent the occurrence of voids by aligning and transferring the transfer bumps and diffusing the metal layer into the transfer bumps.

Further, as to the problem: the generation of the solder balls of 4, as described in claim 9, 10 or 11, the transfer bump is provided with a non-wetting peripheral layer around the transfer bump formation region. , After the deposition process is finished, the transfer bumps are melted by melting and then the peripheral cover layer is removed, or a non-wettable peripheral cover layer is provided on the transfer bumps around the metallized layer for electrodes to transfer the transfer bumps. After the process is completed, it is solved by removing the surrounding layer. A metal layer that can be removed by etching differently from the bumps, or a resin layer that can be dissolved and removed by a solvent is effectively used as the surrounding layer.

Further, as for the problem: peeling of the bumps by the mask vapor deposition method of 5, as described in claim 12 or 14, a plurality of metal masks having openings having different dimensions are superposed and the side walls of the openings are covered. It is designed to expand like a staircase. Then, the side of the opening that contacts the bump original plate is made larger. In this way, since the side wall of the opening of the metal mask escapes in the direction of expansion, it is possible to prevent the bump material from adhering to the side wall of the opening even if the bump material wraps around and is mask-deposited. It is possible to prevent the formed bumps and transfer bumps from peeling together when peeling from the substrate on which the bumps are to be formed or the bump original plate.

On the other hand, regarding the problem of forming large bumps in the method of forming bumps by plating using a resist as a mask, as described in claims 19 to 23, a thin film of electrode metal or metal particles is formed by reverse sputtering to form electrode metal. The conductive film for plating can be formed by forming the conductive film also on the insulating film surrounding the, and it is possible to accurately form fine and high-density bumps on the electrode by electrolytic plating.

As a result, the present invention largely contributes to the improvement of the yield and the cost reduction of the manufacturing process of the semiconductor device including the flip chip bonding in the manufacturing process.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a first embodiment of the present invention.

FIG. 2 is an explanatory view of a second embodiment of the present invention.

FIG. 3 is an explanatory view of a third embodiment of the present invention.

FIG. 4 is an explanatory view of a fourth embodiment of the present invention.

FIG. 5 is an explanatory diagram of a fifth embodiment of the present invention.

FIG. 6 is an explanatory diagram of a sixth embodiment of the present invention.

FIG. 7 is an explanatory diagram of a seventh embodiment of the present invention.

FIG. 8 is a schematic process diagram of a method for forming bump solder according to the present invention.

FIG. 9 is a schematic explanatory view of the steps of the eighth embodiment of the present invention (part 1)

FIG. 10 is a schematic explanatory view (2) of process steps of the eighth embodiment of the present invention

FIG. 11 is a micrograph of the bump solder of the present invention after formation.

FIG. 12 is a micrograph of a completed solder bump after melting the solder for bumps of the present invention.

FIG. 13 is a schematic process diagram of a bump forming method by a transfer method.

FIG. 14: Actual measurement value of height of bump formed by vapor deposition method

FIG. 15 is a schematic diagram illustrating the occurrence of voids in bumps.

FIG. 16 is a schematic diagram illustrating generation of a solder mass from a wraparound film.

FIG. 17 is a schematic diagram illustrating peeling of bumps by a vapor deposition method.

FIG. 18 is a schematic process diagram of a conventional bump solder forming method.

FIG. 19 is a photomicrograph of a conventional example of bump solder after formation.

[Explanation of symbols]

 1 Bump original plate 2 Substrate 3 Bump 4 Flux 5 Metal mask 5a First mask 5b Second mask 6 Metal layer 7 Circumference layer 11 Transfer bump 21 Electrode metallization layer 22 Insulation film 31 Solder mass 51 Stacked body 61 Semiconductor substrate 62 metal electrode 63 insulating film 64 metal film or metal particle 65 dry film or liquid resist 66 opening 67 solder 68 solder bump 71 Si wafer 72 Ti film 73 Ni film 74 metal electrode 75 polyimide film 76 through hole 77 metal film or metal particle 78 Dry film 79 Opening 80 Solder 81 Solder bump

Claims (23)

[Claims] 1. A semiconductor device having bumps formed by transferring a plurality of transfer bumps provided on a bump original plate to a plurality of electrode metallization layers provided on a substrate, wherein the transfer bumps have a diameter of However, the semiconductor device is characterized in that it is formed to be smaller than a gap between the adjacent metallized layers for electrodes and a pitch smaller than a pitch of the metallized layers for electrodes. 2. The semiconductor device according to claim 1, wherein the bump original plate is made of glass, silicon, ceramic or plastic. 3. The semiconductor device according to claim 1, wherein the surface of the substrate other than the metallization layer for electrodes is covered with an insulating material that is not wet with the transfer bumps. 4. The transfer bump is formed of Pb, Sn, I
The semiconductor device according to claim 1, which is made of a solder containing at least one of n, Bi, Ga, Ge, and Sb. 5. The method of manufacturing a semiconductor device according to claim 1, further comprising a transfer step of transferring the transfer bump on the bump original plate to the electrode metallization layer on the substrate. A method for manufacturing a semiconductor device, comprising: 6. The semiconductor device according to claim 5, further comprising, after the transferring step, a removing step of cleaning a solder mass generated between bumps formed on the substrate and scattered together with the flux applied in the transferring step. Manufacturing method. 7. A method of manufacturing a semiconductor device, comprising: a transfer step of transferring a transfer bump formed by vapor deposition to a substrate through a plurality of openings of a metal mask stacked on a bump original plate; A method of manufacturing a semiconductor device, characterized in that a metal mask including an opening area of 20% or less of a predetermined area is used as a defect and is not used, and the transfer step is repeated a plurality of times. 8. A method of manufacturing a semiconductor device, comprising a transfer step of transferring transfer bumps provided on a bump original plate to a plurality of electrode metallization layers formed in an insulating layer provided on a substrate, A step of providing a metal layer so as to extend over the electrode metallization layer and the insulating layer, and the metal layer wets and diffuses on the transfer bumps, and in the transfer step, the transfer bumps are formed. Aligning the metal layer with the metal layer, the method for manufacturing a semiconductor device. 9. A semiconductor device including a transfer step of transferring a transfer bump formed on a bump original plate by a vapor deposition step to an electrode metallization layer provided on a substrate to form a bump on the substrate. In the manufacturing method, a step of providing a non-wetting peripheral covering layer on the transfer bump around the transfer bump forming region; and, after the vapor deposition step is finished, the transfer bump is melted by heating and then the transfer bump is melted. And a step of removing the surrounding layer, the method for manufacturing a semiconductor device. 10. A method of manufacturing a semiconductor device, comprising: a transfer step of transferring a transfer bump provided on a bump original plate to an electrode metallized layer provided on a substrate to form the bump on the substrate. A semiconductor device comprising: a step of providing a non-wetting peripheral cover layer on the transfer bump around the electrode metallization layer; and a step of removing the peripheral cover layer after the transfer step is completed. Device manufacturing method. 11. The method of manufacturing a semiconductor device according to claim 9, wherein the surrounding layer is a metal layer that can be removed by etching in a manner that is different from the bumps, or a resin layer that can be dissolved and removed by a solvent. 12. A method of manufacturing a semiconductor device, comprising: a step of depositing bumps on an electrode metallization layer provided on a substrate through an opening of a metal mask that is overlaid on the substrate. A method for manufacturing a semiconductor device, comprising an overlapping body of a plurality of metal masks having openings having different sizes, and the openings are arranged so as to spread toward the substrate. 13. The transfer bump comprises Pb, Sn, I
13. The method of manufacturing a semiconductor device according to claim 12, comprising a solder containing at least one of n, Bi, Ga, Ge and Sb. 14. A method of manufacturing a semiconductor device, comprising: a transfer step in which a transfer bump deposited through an opening of a metal mask placed on a bump original plate is transferred to an electrode metallization layer on a substrate. Manufacturing of a semiconductor device, wherein the mask is composed of an overlapping body of a plurality of metal masks having openings having different sizes, and the openings are arranged so as to spread toward the bump original plate. Method. 15. The method of manufacturing a semiconductor device according to claim 7, wherein the bump original plate is made of at least one of glass, silicon, ceramics, and plastics. 16. The method of manufacturing a semiconductor device according to claim 7, wherein the surface of the substrate other than the metallization layer for electrodes is covered with an insulating material which is not wet with the transfer bumps. 17. The transfer bump comprises Pb, Sn, I
15. The method of manufacturing a semiconductor device according to claim 7, comprising a solder containing at least one of n, Bi, Ga, Ge and Sb. 18. A semiconductor device, which is formed by the method for manufacturing a semiconductor device according to claim 7, 8, 9, 10, 12 or 14. 19. A method of manufacturing a semiconductor device having a solder bump formed by plating using a resist as a mask on a semiconductor substrate on which a metal electrode is formed, which withstands the melting point of solder on the semiconductor substrate on which the metal electrode is formed. A step of covering an insulating film except on the metal electrode, and a step of covering the insulating film with a resist for plating to form an opening including the metal electrode and having a diameter larger than at least the metal electrode. And a step of plating solder in the opening, and a step of heating and melting the solder to form spherical solder bumps. 20. A semiconductor substrate on which the metal electrode is formed is covered with an insulating film that withstands the melting point of solder except on the metal electrode, and then the surface of the metal electrode is reverse-sputtered to form an insulating film on the insulating film. 20. The method for manufacturing a semiconductor device according to claim 19, further comprising depositing a metal film or metal particles on the surface. 21. The method of manufacturing a semiconductor device according to claim 19, wherein the insulating film is a polyimide film. 22. The method of manufacturing a semiconductor device according to claim 19, wherein a polyimide film is used as the insulating film for plating. 23. The solder is Pb, Sn, Ag, S
21. The method of manufacturing a semiconductor device according to claim 19, further comprising at least one component selected from b, In and Bi.