JP2003197672A - Method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate a disadvantage that an interval, between a semiconductor chip and a chip mounting object, becomes narrower, which is generated when excessive pressure and heat are applied in order to connect connecting portions while absorbing fluctuations of heights of bumps in the flattening process of the connecting portion, which is performed to increase a contact area by making it flat and connecting the connecting portions of both connecting objects to assure good contact conditions at the time of connecting the bumps formed by a wire bonding apparatus. <P>SOLUTION: Projected metal portions 3, 13 are provided on an electrode pad of a semiconductor element 1 and a connecting pad of a chip mounting object 11, and either of projected portions is formed to have a sharp end point, while the other is formed to have a flat end point. Accordingly, positioning accuracy between the projected metal portions can be alleviated and the projected metal portions have allowances to absorb deviations generated at the connecting portions due to the difference of thermal expansion coefficients of the semiconductor element 1 and the chip mounting object 11. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a face-down mounted semiconductor device which can be realized at low cost and a method for manufacturing the same.

[0002]

2. Description of the Related Art In a method of manufacturing a semiconductor device according to the present invention, it is an important factor to provide a convex metal projection and a flat metal projection on both objects to be connected.

For this purpose, usually, as shown in FIG. 4, a wire bonding device is used to form gold-containing bumps 63 and 73 on a semiconductor chip 61 and a chip-to-be-mounted object 71, respectively. Face each other and perform flip chip bonding. Flip chip bonding is performed at room temperature to 200 ° C., and the gold-containing bumps on both sides may be subjected to a flattening process in advance. With such a configuration, a method of manufacturing a chip-on-chip structure in which a semiconductor chip is used as a mounted object and a gap between the chips is filled with a sealing material, and a substrate is mounted as the mounted object and the gap between the chips is sealed. A method called a method of manufacturing a chip-on-board structure filled with a material is adopted.

[0004]

However, in this method, when the bumps formed by the wire bonding apparatus are connected to each other, both connection parts of the connection object are flattened and bonded in order to obtain a good connection. In order to increase the contact area at the time, it is necessary to perform a flattening process on the connection part. When the connection part is flattened, excessive pressure and heating are required to absorb the height variation between the bumps and connect the connection parts. As a result, the gap between the semiconductor chip and the chip mounted object becomes narrow. There will be a problem. More detailed explanation is as follows.

In the case of an ideal flattening process, all bumps have the same height, but when such a process is applied to an actually manufactured bump, for example, two flat plates are prepared and one side is prepared. When the chip is placed on the plate and the other plate is lowered to flatten the bumps on the chip, the flatness of the plate has a tolerance of several μm, and the parallelism of the two flat plates is several μm. There is some tolerance. As a result, the highest bump and the lowest bump are several μm (empirically 1
The difference in height of bumps formed over an area of 0 mm square is about 5 μm at maximum). This phenomenon occurs with respect to the bumps of the connection objects on both sides to be joined, and in the worst combination, when the highest bumps and the lowest bumps of the connection objects are connected to face each other, When the high bumps come into contact with each other, the gap between the low bumps becomes as much as ten and several μm.

Therefore, in order to eliminate this gap and connect the low bumps to each other, it is necessary to crush the high bumps by several tens of μm. Therefore, if the bumps have already been leveled to increase the contact area when flattening and joining the connection parts, excessive pressure and heating will occur compared to the bumps when the contact area before leveling is small. It is necessary. Further, when the bumps subjected to the flattening treatment are used, it is not suitable for a method of previously supplying a liquid encapsulating material to be put into a gap between the semiconductor chip and the chip mounted object or a method of using a film encapsulating material . However, when connecting the bumps formed by the wire bonding device without performing the flattening process, the tip of the bump has a diameter of about several μm.
Accurately aligning these is extremely difficult.
Therefore, a flattening process is required, but even if the height is accurately processed, a variation of about several μm occurs. Therefore, excessive pressure and heating are required to absorb the variation in height and connect. Will be needed. As a result, there arises a problem that the gap between the semiconductor chip and the chip mounted object becomes narrow. Further, when the bumps subjected to the flattening process are used, since the bumps are hardly deformed, the effect of eliminating the sealing material due to the deformation cannot be expected. That is,
When attention is paid to the bumps to be joined that have been subjected to the flattening process, the parallelism of the joint surfaces of the bumps can be regarded as almost parallel because the diameter of the bump is several tens of μm. Therefore, once the resin has entered between the bumps to be joined, the resin can be excluded from the bumps to be joined by simply pushing the connecting object on one side against the connecting object on the other side. It is difficult. Therefore, the method of performing the flattening process on the bumps of the connection target before the connection of the connection target is not suitable for the method of previously supplying the liquid sealing resin or the method of using the film-shaped sealing resin.

One of the main objects of the present invention is to provide a semiconductor device which improves the reliability of connection by absorbing the height variation of the metal projections and further widening the gap.

[0008]

A method of manufacturing a semiconductor device according to the present invention comprises a first substrate having a first conductive protrusion and a second substrate.
And a second substrate having a conductive convex portion of the first and second
Is a method for manufacturing a semiconductor device in which the first and second substrates are arranged to face each other by bonding the conductive protrusions to each other, wherein the first conductive protrusion has a flat top surface, Each of the second conductive protrusions is formed in a shape with a protruding tip, and the first conductive protrusion and the second conductive protrusion are joined to each other such that the tip of the second conductive protrusion is connected to the first conductive protrusion. The first protrusion is placed at a position that is planarly accommodated in the flat top surface of the convex portion.
And the second substrate are arranged, and thereafter, at least one of the first and second substrates is pressed in a direction in which the facing distance between the first and second substrates is reduced. And The semiconductor device of the present invention has the following suitable application modes.

First, the hardness of the second conductive protrusion is higher than the hardness of the first conductive protrusion.

Secondly, of the first and second substrates,
At least one of the substrates is a semiconductor substrate.

Thirdly, after the first and second conductive convex portions are joined, a resin is injected between the first conductive substrate and the second conductive substrate to cure the resin. Seals between the first and second substrates.

Fourth, before joining the first and second conductive convex portions, the conductive convex portion of at least one of the first conductive substrate and the second conductive substrate is removed. Also, a resin is formed inside the substrate, and the resin seals between the first and second substrates by bonding the first and second conductive protrusions. .

Fifth, the first conductive convex portion is formed by a plating method, and the second conductive convex portion is formed by a ball bonding method, respectively. Manufacturing method of semiconductor device.

Sixth, the step of pressurizing at least one of the first and second substrates is pressurization involving heating.

Seventh, the step of pressurizing at least one of the first and second substrates is pressurization involving ultrasonic connection.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of a method of manufacturing a semiconductor device according to the present invention will be described with reference to sectional views of manufacturing steps shown in FIG.

A convex metal projection 2 is formed on the electrode pad (not shown) of the first semiconductor element 1 by a ball bonding method, and then a tip different from the top shape of the metal projection 2 is formed. A metal projection 3 having a pointed shape is formed. On the other hand, a convex metal protrusion is formed on the electrode pad (not shown) of the second semiconductor element 11 by a ball bonding method, and then the metal protrusion is added using a flat plate that is harder than the metal protrusion. The metal projection 13 is flattened by pressure (FIG. 1A).

After the metal protrusions 3 on the first semiconductor element 1 and the metal protrusions 13 of the second semiconductor element 11 are opposed to each other and aligned (FIG. 1 (b)), the first semiconductor element is then aligned. A load is applied to either or both of the first and second semiconductor elements 11 (FIG. 1C). At this time, in addition to the load, any or all of heating and ultrasonic waves are applied to connect the metal projections 3 and the metal projections 13 to each other.

After the connection is completed, the liquid sealing resin is poured into the gap between the first semiconductor element 1 and the second semiconductor element 11 by utilizing the capillary phenomenon to heat and cure the sealing resin 14 (FIG. 1 (d). )).

The semiconductor element thus manufactured can be handled in the same manner as one conventional semiconductor element, and then completed by the conventional manufacturing method.

In the method according to the present embodiment, since the metal projection 3 having a pointed top and the metal projection 13 having a flat top are used in combination, the metal projection 3 and the metal projection 13 are aligned with each other. There is an advantage that the projection 13 becomes larger than the metal projection 3 and good connection between the metal projection 3 and the metal projection 13 can be obtained even if the positioning accuracy of the metal projection 3 is relaxed.

Further, by using the metal protrusion 3 having a pointed top, it is possible to absorb the height variation of the protrusion itself and the height variation of the metal protrusion 13 of the connection partner by the deformation of the pointed tip. Therefore, as a whole, the first semiconductor element 1
The first semiconductor element 1 and the second semiconductor element 1 by absorbing the height variation of the joining metal between the second semiconductor element 11 and the second semiconductor element 11.
A stable connection between 1 can be obtained.

In the above embodiment, the metal protrusion 13 may be formed by using a plating method.

Further, by making the hardness of the metal projection 3 having a sharp top higher than that of the metal projection 13, it is possible to make the top of the metal projection 3 bite into the flat portion of the metal projection 13 and to provide an anchor effect. A stable connection can be obtained. When the metal protrusion 13 is formed by the plating method, the hardness thereof can be adjusted by the annealing treatment, and the one having a low hardness can be obtained.

Next, a second embodiment of the method of manufacturing a semiconductor device according to the present invention will be described with reference to the manufacturing process sectional view of FIG.

In the previous embodiment, the present invention was applied to the connection between semiconductor elements, but in the present embodiment, it is also applied to the connection between a semiconductor element and a wiring board.

Electrode pads of the semiconductor element 21 (not shown)
The flat metal projections 22 are formed on the top of the wiring board 35 on the wiring board 31 by a ball bonding method.
Is formed, and a metal projection 33 having a sharp tip, which is harder than the metal projection 32, is formed. A back surface pad 37 is provided on the wiring board 31 on the side opposite to the semiconductor element 21 via a connection plug 36.

Next, after the metal projections 23 on the semiconductor element 21 and the metal projections 33 on the wiring board 31 are opposed to each other and aligned (FIG. 2A), the semiconductor element 21 and the wiring board 3 are aligned.
The load is applied to either or both of No. 1 and No. 1. At this time, in addition to the load, any or all of heating and ultrasonic waves are applied to connect the metal projections 23 and the metal projections 33.

After the connection is completed, the liquid sealing resin 34 is poured into the gap between the semiconductor element 21 and the wiring board 31 by utilizing the capillary phenomenon to heat and cure the sealing resin 34 (FIG. 2).
(B)).

Thereafter, for example, the back surface pad 3 is provided on the wiring substrate 31 on the side opposite to the semiconductor element 21 via the connection plug 36.
7 and the external terminal 38 are formed to obtain a semiconductor device.

Therefore, the semiconductor element 21 and the wiring board 3 are
In the connection with 1, the metal projections and the metal projections are formed on the wiring pads 35 of the wiring board 31, so that even if inexpensive plating such as flash gold plating is adopted for the surface finish of the wiring pads 35, the semiconductor element 21 is formed. It is possible to obtain a good connection between the wiring board 31 and the wiring board 31.

In addition, since the metal protrusion is formed on the wiring pad 35 of the wiring board 31, the gap between the semiconductor element 21 and the wiring board 31 is widened. Therefore, it is possible to relieve the stress applied to the connection portion due to the difference in thermal expansion between the semiconductor element 21 and the wiring board 31, and the connection reliability is improved.

Next, a third embodiment of the method of manufacturing a semiconductor device according to the present invention will be described with reference to the manufacturing process sectional view of FIG. The present embodiment shows a case where the sealing resin is supplied to one of the connection objects in advance and then the connection objects are joined.

A convex metal projection 42 is formed on the electrode pad (not shown) of the first semiconductor element 41 by a ball bonding method, and subsequently, a tip different from the top shape of the metal projection 42 is formed. A metal projection 43 having a pointed shape is formed. On the other hand, a flat metal projection 53 is formed on the electrode pad (not shown) of the second semiconductor element 51 by a plating method.

Next, after the sealing resin 54 is applied on the second semiconductor element 51, the metal protrusion 43 on the first semiconductor element 41 and the metal protrusion 53 on the second semiconductor element face each other. And aligning (FIG. 3A), a load is applied to either or both of the first semiconductor element 41 and the second semiconductor element 51 to connect the metal protrusion 43 and the metal protrusion 53 to each other. At the same time, the sealing resin 54 is cured by heating. At this time, ultrasonic waves may be used together. If necessary, heat is further applied thereafter to completely cure the sealing resin 54.

Therefore, the structure is the same as that of the first and second embodiments except that the sealing resin 54 is supplied in advance, and the object of the present invention is achieved. In addition, since the flat metal projection is formed on the electrode pad of the second semiconductor element by using the plating method, the sealing resin creeps up to the surface of the metal projection by the height of the metal projection. Can be prevented. Further, since the metal protrusion 53 having a sharp tip is used, the first semiconductor element 41 is eliminated while the sealing resin 54 is removed at this tip.
Since the second semiconductor element 51 and the second semiconductor element 51 can be connected, the sealing resin 54 is provided between the metal protrusion 43 and the metal protrusion 53.
There is a synergistic effect that it is possible to significantly reduce the possibility of sandwiching. Further, when the sealing resin 54 is supplied in the form of a film, it is not possible to prevent the resin from climbing up to the surface of the metal projection 43, but the metal projection 5
It is possible to sufficiently remove the sealing resin 54 at the tip of 3.

As described above, in the present embodiment, when the tip of the bonding bump formed on one of the objects to be connected has a sharp shape, this sharp portion is a resin protruding laterally at the time of bonding. Since it sticks to the bump of the other connection target while scraping off, the resin does not exist between the tip of the sharp bump and the other bump.

As described above, according to the method of manufacturing a semiconductor device of the present invention, when the semiconductor element and the object to be mounted are connected through the metal projection, the electrode pad of the semiconductor element is connected to the object to be mounted. Metal protrusions are provided on the pads, and one of the protrusions has a sharp tip and the other has a flat top, and these metal protrusions are joined together to connect the two. The difference in the shape of the metal protrusions serves to ease the alignment accuracy between the metal protrusions. Further, these metal protrusions serve to electrically connect, and at the same time, even if the connection portion is displaced due to the difference in thermal expansion between the semiconductor element and the mounted object, it is acceptable to absorb the displacement. Have a degree.

Furthermore, by providing different hardnesses for the metal projection materials, it is possible to obtain a structure in which hard, pointed metal projections are bitten into a soft flat metal projection.

Therefore, since the alignment accuracy can be relaxed, a high yield can be obtained, and the difference due to thermal expansion can be relaxed, so that a high connection reliability can be obtained, and the metal protrusion at one connection point can be connected to the other metal protrusion at the other. Since it has a shape that digs into the metal protrusion, there is an effect that a stable connection between the objects to be connected can be obtained.

[0041]

According to the method of manufacturing a semiconductor device according to the present invention, when connecting a semiconductor element and an object to be mounted via a metal protrusion, the semiconductor element is mounted on the electrode pad of the semiconductor element and the connection pad of the object to be mounted. By providing the metal protrusions and forming one of the protrusions with a pointed tip and the other with a flat top, the alignment accuracy of the metal protrusions can be eased. Further, these metal protrusions have a tolerance that can absorb the deviation even if the connection portion is deviated due to the difference in thermal expansion between the semiconductor element and the mounted object. Therefore, by relaxing the alignment accuracy, a high assembly yield can be obtained, and the difference due to thermal expansion can be mitigated, so that high connection reliability can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a method of manufacturing a semiconductor device according to a first embodiment of the present invention in the order of manufacturing steps.

FIG. 2 is a cross-sectional view showing a method of manufacturing a semiconductor device according to a second embodiment of the present invention in the order of manufacturing steps.

FIG. 3 is a cross-sectional view showing a method of manufacturing a semiconductor device according to a third embodiment of the present invention in the order of manufacturing steps.

FIG. 4 is a cross-sectional view showing a method of manufacturing a conventional semiconductor device in the order of manufacturing steps.

[Explanation of symbols]

1, 41 First semiconductor element 2, 13, 23, 32, 42, 53 Metal protrusion 3, 33, 43 Metal protrusion 11, 51 Second semiconductor element 14, 34, 54 Sealing resin 21 Semiconductor element 31 wiring board 35 wiring pad 36 connection plug 37 Back pad 61 Semiconductor chip 63, 73 Gold bump 71 Chip mounted object

Claims (8)

[Claims] 1. A first substrate having a first conductive protrusion and a second substrate having a second conductive protrusion are bonded to each other with the first and second conductive protrusions. Is a method for manufacturing a semiconductor device in which the first and second substrates are arranged to face each other, wherein the first conductive protrusion has a flat top surface and the second conductive protrusion has a tip. Are respectively formed in a protruding shape, and the first and second conductive protrusions are joined to each other such that the tips of the second conductive protrusions are located within the flat top surface of the first conductive protrusion. The first and second substrates are arranged in a position that fits in a plane, and then at least one of the first and second substrates is placed in a direction in which the facing distance between the first and second substrates is reduced. A method for manufacturing a semiconductor device, which is performed by applying pressure. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the hardness of the second conductive protrusion is higher than the hardness of the first conductive protrusion. 3. The method of manufacturing a semiconductor device according to claim 1, wherein at least one of the first and second substrates is a semiconductor substrate. 4. After the first and second conductive convex portions are joined together, a resin is injected between the first conductors and the first and second substrates and cured, so that the resin is cured. The first conductor seals a space between the first and second substrates.
Alternatively, the method for manufacturing a semiconductor device according to the above item 3. 5. Prior to joining the first and second conductive protrusions, the first conductor is a substrate more than the conductive protrusion of at least one of the first and second substrates. A resin is formed on the inside of the substrate, and the resin seals between the first and second substrates by joining the first and second conductive protrusions. 4. The method for manufacturing a semiconductor device according to 1, 2 or 3. 6. The semiconductor device according to claim 1, wherein the first conductive protrusion is formed by a plating method, and the second conductive protrusion is formed by a ball bonding method. Manufacturing method. 7. The method of manufacturing a semiconductor device according to claim 1, wherein the step of pressurizing at least one of the first and second substrates is pressurization accompanied by heating. 8. The manufacturing of a semiconductor device according to claim 1, wherein the step of pressurizing at least one of the first and second substrates is pressurization involving ultrasonic connection. Method.