JP4629284B2 - Semiconductor device and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor device in which a substrate and a semiconductor chip are connected by a thin metal wire, and a manufacturing method thereof.
[0002]
[Prior art]
One method for electrically connecting a semiconductor chip and a substrate having a metal wiring portion or the like is a wire bonding method.
In the wire bonding method, an electrical connection between the substrate and the semiconductor chip is achieved by connecting the substrate and the semiconductor chip with a fine metal wire. The wire bonding apparatus is provided with a capillary for feeding and press-contacting a fine metal wire. The capillary is lowered so as to be close to a horizontally mounted substrate, is lifted away from the substrate, or moved horizontally with respect to the substrate, so that the gap between the substrate and the semiconductor chip is reduced. Connect with fine metal wires.
[0003]
FIG. 4 is a schematic side view of a semiconductor device in which a semiconductor chip and a substrate are connected using a general wire bonding method.
The semiconductor chip 12 is fixed on the substrate 11 with an adhesive 19. General wire bonding includes a first connection that connects one end 15 of the fine metal wire 18 to the semiconductor chip 12 side, and a second connection that connects the other end 17 of the fine metal wire to the substrate 11 side.
[0004]
Before the metal thin wire 18 is pressed against the semiconductor chip 12 side, the tip 15 of the metal thin wire 18 is processed into a spherical shape for the convenience of pressure contact by the capillary tip. Since the other end 17 of the fine metal wire 18 can be pressed against the wiring part 14 with a capillary before cutting the fine metal wire 18, spherical processing is not necessary.
After the connection, the fine metal wire 18 forms an arc-shaped wire loop 18a. The height from the connection surface between the electrode pad 13 of the semiconductor chip 12 and the tip 15 of the thin metal wire 18 to the apex of the wire loop 18a is called the loop height 18b.
[0005]
In normal wire bonding, the loop height 18 b is increased, and the fine metal wires 18 are easily bent in a direction horizontal to the substrate 11. For this reason, a phenomenon called curl occurs in which adjacent wires approach each other, and the electrical connection between the semiconductor chip 12 and the substrate 11 may become unstable.
Therefore, in order to keep the loop height 18a low and prevent curling, a reverse wire bonding method has been developed.
[0006]
FIG. 5 is a schematic side view of a semiconductor device in which a semiconductor chip and a substrate are electrically connected by a reverse wire bonding method.
The reverse wire bonding method includes a first connection that connects the tip 15 of the metal thin wire 18 to the substrate 11 side, and a second connection that connects the other end 17 of the metal thin wire 18 to the semiconductor chip 12 side. The tip 15 of the fine metal wire 18 is processed into a spherical shape, but the other end 17 of the fine metal wire 18 is not particularly processed.
[0007]
In this reverse wire bonding method, since the fine metal wires 18 do not rise vertically from the upper surface of the semiconductor chip 12, the loop height 18b can be kept low compared to the normal wire bonding method. Therefore, curling can be prevented.
[0008]
[Problems to be solved by the invention]
However, in the reverse wire bonding method, the first connection is ball bonding in which the tip 15 of the fine metal wire 18 is made spherical and then connected to the substrate 11. This ball bonding has a lower adhesion than the stitch bonding in which the fine metal wires 18 are connected without spherical processing.
On the other hand, since the substrate 11 is easily affected by a thermal history such as a manufacturing process, there is a problem that the tip portion 15 which is a ball bonding portion is easily peeled off from the wiring portion 14 of the substrate 11.
[0009]
FIG. 6 is a cross-sectional view conceptually showing a difference in how the bonding power is transmitted due to a difference in bonding area. 6A shows a state in which the fine metal wire 18 delivered from the capillary tip 10 is stitch-bonded to the wiring part 14 formed on the substrate 11, and FIG. A state in which the fine metal wire 18 to be delivered is ball bonded to the wiring portion 14 formed on the substrate 11 is shown.
[0010]
The bonding area is the area of the contact portion between the fine metal wire 18 and the wiring portion 14.
The pressure contact force (bonding power) from the capillary is dispersed over the entire bonding area. Therefore, the smaller the bonding area, the larger the bonding power per unit area, and the stronger adhesion can be obtained.
As is apparent from the comparison between FIGS. 6A and 6B, the bonding area 90 in the case of ball bonding is much larger than the bonding area 80 in the case of stitch bonding. Therefore, in the case of ball bonding, the bonding power is dispersed over a large area, and the bonding strength is weakened. Therefore, in the case of the reverse wire bonding method in which ball bonding is performed on the substrate 11 side, the thin metal wires 18 are easily peeled off from the wiring portion 14 on the substrate 11.
[0011]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-described technical problems and provide a semiconductor device excellent in connection stability between a substrate and a semiconductor device and a method for manufacturing the same.
[0012]
[Means for Solving the Problems and Effects of the Invention]
In order to achieve the above object, the invention according to claim 1 includes a substrate (1), a semiconductor chip (2) having an electrode pad (3) on the surface, and a first position on the substrate (1). A tip portion (5) ball-bonded to the substrate, an intermediate portion (6) stitch-bonded to a second position different from the first position on the substrate (1), and an electrode of the semiconductor chip (2) pad (3) seen containing a metal fine wire (8) having stitch bonded end portion (7) on, the second position, the than the first position, away from the semiconductor chip (2) The semiconductor device is characterized by being a position . The numbers in parentheses indicate corresponding components in the embodiments described later. The same shall apply hereinafter in this section.
[0013]
According to said structure, a semiconductor chip and a board | substrate are connected using three points, the front-end | tip part of one metal thin wire | line, the middle part, and the termination | terminus part.
Of the three connections, the tip of the fine metal wire is pressed into contact with the first position on the substrate by ball bonding, and the middle portion of the fine metal wire is stitched at a second position different from the first position on the substrate. Bonded. Therefore, since connection at two points with different positions and connection methods is performed on the substrate, the connection stability is excellent, and there is no possibility that the electrical connection between the fine metal wire and the substrate is broken.
[0014]
Further, since the terminal end of the fine metal wire is stitch-bonded on the electrode pad on the surface of the semiconductor chip, stable electrical connection between the semiconductor chip and the substrate can be realized.
According to the second aspect of the present invention, there is provided a first step of connecting the tip (5) of the thin metal wire (8) to a first position on the substrate (1), and the substrate (1) after the first step. A second step of connecting the middle portion (6) of the fine metal wire (8) to a second position different from the first position above, and an electrode on the surface of the semiconductor chip (2) after the second step look including a third step of connecting the end portion of the thin metal wire on the pad (3) (8) (7), the second step, the second position, the than the first position A method for manufacturing a semiconductor device, comprising a step of connecting the intermediate portion (6) of the thin metal wire (8) so as to be located far from the semiconductor chip (2) .
[0015]
According to the above configuration, the fine metal wire is connected to the substrate side first (first step, second step), and then the fine metal wire is connected to the semiconductor chip side (third step). Low loop wire bonding is feasible. Therefore, it is possible to provide a semiconductor device that is excellent in electrical connection stability without curling.
Moreover, in order to connect the front-end | tip part of a metal fine wire to the 1st position on a board | substrate, and to connect the middle part of a metal fine wire to the 2nd position different from the 1st position on a board | substrate after that, Improved connection stability is achieved.
[0016]
According to a third aspect of the present invention, in the first step, a spherical portion is formed at the tip (5) of the fine metal wire (8), and the spherical portion is pressed against the first position on the substrate (1). The second step includes stitch bonding that presses the middle part (6) of the fine metal wire (8) to the second position on the substrate (1), and the third step includes: 3. The method of manufacturing a semiconductor device according to claim 2, further comprising stitch bonding that presses the terminal portion (7) of the thin metal wire (8) onto the electrode pad (3) on the surface of the semiconductor chip (2). is there.
[0017]
With the above configuration, in the first step, the metal fine wire tip is pressed by ball bonding on the substrate side in the first step, and in the second step, the metal fine wire intermediate portion is pressed on the substrate side by stitch bonding. Improved connection stability. In addition, since the metal wire end portion is press-contacted to the electrode pads on the semiconductor chip by stitch bonding, a low-loop connection is achieved, and electrical connection stability is improved.
[0018]
It said second position, Ru farther der from the semiconductor chip than the first position. Thereby, the wire loop shape between the middle part and the terminal part of a metal fine wire can be stabilized.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic side view of a semiconductor device according to an embodiment of the present invention.
The semiconductor chip 2 is fixed on the substrate 1 with an adhesive 9. In another area on the substrate 1, a wiring portion 4 is formed of metal, and the wiring portion 4 of the substrate 1 and the electrode pad 3 on the surface of the semiconductor chip 2 are electrically connected via a thin metal wire 8. .
[0020]
The tip portion 5 of the metal thin wire 8 is a ball bonding portion formed by pressing the tip portion 5 into a spherical shape and then being pressed against the first position P1 on the substrate 1. The middle portion 6 of the fine metal wire 8 is stitch-bonded at a second position P2 different from the first position P1 on the substrate 1. It is preferable that both the first position P1 and the second position P2 are on the wiring portion 4. In order to stabilize the shape of the wire loop 8a (particularly between the midway portion 6 and the electrode pad 3), the second position P2 is farther from the semiconductor chip 2 than the first position P1. Good. The terminal portion 7 of the thin metal wire 8 is stitch bonded on the electrode pad 3 on the surface of the semiconductor chip 2.
[0021]
Between the front-end | tip part 5 and the intermediate part 6 of the metal fine wire 8, and between the intermediate part 6 and the termination | terminus part 7, the wire loop 8a formed with the metal fine wire 8 exists, respectively. Since the connection is based on the reverse wire bonding method, the loop height 8b between the middle portion 6 and the end portion 7 of the thin metal wire 8 is lower than that in the normal wire bonding.
A wide range of materials from inorganic materials to polymer materials can be used for the substrate 1.
The substrate 1 may be a printed wiring board. The metal thin wire 8 is preferably made of a metal having good electrical conductivity. In detail, it is preferable to use Au fine wire. Al, Cu, Au, etc. are generally used as the fine metal wires, but among these, Au is a metal that is particularly excellent in electrical conductivity and is not corroded by moisture in the atmosphere. Has the highest stability and reliability.
[0022]
In the semiconductor device according to this embodiment, the bonding strength on the substrate 1 side is improved by connecting the wiring portion 4 and the metal thin wire 8 on the substrate 1 at two locations. The ball bonding part pressed against the substrate 1 is usually easily peeled off due to the heat effect in the manufacturing process. However, by additionally performing stitch bonding with strong adhesion on the wiring part 4, the stability of electrical connection Is secured.
The terminal portion 7 of the thin metal wire 8 is pressed against the electrode pad 3 on the surface of the semiconductor chip 2 by stitch bonding. Therefore, the connection reliability on the semiconductor chip 2 side is sufficient.
[0023]
2A to 2D and 3E to 3G are schematic side views showing the manufacturing steps of the semiconductor device in the order of steps.
A wire bonding apparatus is used to electrically connect the substrate 1 and the semiconductor chip 2 using the fine metal wires 8. This apparatus is provided with a capillary 20 for feeding and press-contacting the fine metal wire 8. The capillary 20 moves in a horizontal direction that is parallel to the substrate 1 and a vertical direction that is in contact with and away from the substrate 1 in order to connect the substrate 1 and the semiconductor chip 2 with the thin metal wires 8. It is possible.
[0024]
The substrate 1 in which the wiring portion 4 is formed and the semiconductor chip 2 is fixed by the adhesive 9 or the like is placed horizontally in the wire bonding apparatus. The capillary 20 stands by at a position away from the substrate 1 upward, and the fine metal wire 8 can be sent through the capillary 20 to the tip of the capillary.
First, a small amount of the thin metal wire 8 is protruded from the tip of the capillary 20, and the tip 5 is processed into a spherical shape using an electric torch or the like. The capillary 20 holding the spherical tip 5 moves in the direction 20a approaching the substrate 1 from above (FIG. 2A).
[0025]
When the capillary 20 further approaches the substrate 1, the tip 5 of the thin metal wire 8 protruding from the tip of the capillary 20 and the wiring part 4 come into contact with each other. At this time, a load (and heat and / or ultrasonic vibration as necessary) is applied from the capillary 20, and the spherical tip 5 is pressed against the wiring part 4 and joined to the first position P 1 of the wiring part 4. Is done. This connection is ball bonding in which the tip 5 of the thin metal wire 8 is processed into a spherical shape and connected (FIG. 2B).
[0026]
After the bonding to the first position P1 is completed, the capillary 20 moves in a direction 20b that is separated vertically upward from the substrate 1. Accordingly, the fine metal wire 8 is sent out (FIG. 2C). When the metal wire 8 having a predetermined length is delivered, the capillary 20 stops moving upward 20b.
Next, the capillary 20 moves in the horizontal direction 20c (in this embodiment, the direction away from the semiconductor chip 2) in order to connect the substrate 1 to the second position P2 different from the first position P1. Begin.
[0027]
As the capillary 20 moves, the fine metal wire 8 is sent out again. After the predetermined length of the fine metal wire 8 is delivered and moved by a predetermined distance in the horizontal direction 20c, the capillary 20 stops moving in the horizontal direction 20c and the delivery of the fine metal wire 8, and then approaches the substrate 1 vertically. The moving direction is changed to the direction 20a. At this time, the fine metal wire 8 is sent out in accordance with the movement of the capillary 20. The capillary 20 continues to move vertically downward 20a approaching the substrate 1 and descends toward the substrate 1 until the substrate 1 and the metal thin wire 8 come into contact with each other. When the fine metal wire 8 and the substrate 1 are in contact, the capillary 20 presses the middle portion 6 of the fine metal wire 8 to the wiring portion 4 and joins at the second position P2.
[0028]
The second position P2 is preferably on the wiring part 4 farther from the semiconductor chip 2 than the first position P1. When the connection to the second position P2 is completed, one wire loop 8a is formed between the first position P1 and the second position P2.
The connection to the second position P2 using the middle portion 6 of the fine metal wire 8 is stitch bonding, and this improves the connection stability (FIG. 2D).
After the connection to the second position P2, the capillary 20 moves again while feeding the fine metal wire 8 in the direction 20b that is separated from the substrate 1 vertically upward. When the capillary 20 moves a predetermined distance and the metal thin wire 8 having a predetermined length is sent out, the capillary 20 stops moving upward vertically 20b (FIG. 3E).
[0029]
After that, the capillary 20 starts to move in the horizontal direction 20 d (direction approaching the semiconductor chip 2) in order to connect the electrode pad 3 on the surface of the semiconductor chip 2 and the thin metal wire 8. As the capillary 20 moves, the fine metal wire 8 is sent out again. After the predetermined length of the fine metal wire 8 is delivered and moved in the horizontal direction 20d by a predetermined distance, the capillary 20 stops moving in the horizontal direction 20d and the delivery of the fine metal wire 8, and approaches the semiconductor chip 2 vertically. The moving direction is changed to 20a, and the fine metal wire 8 is sent again in accordance with the movement of the capillary 20.
[0030]
The capillary 20 continues to move downward vertically 20a closer to the semiconductor chip 2, and descends toward the semiconductor chip 2 until the electrode pad 3 of the semiconductor chip 2 and the metal thin wire 8 come into contact with each other. When the electrode pad 3 of the chip 2 comes into contact, the terminal portion 7 of the fine metal wire 8 is pressed against the electrode pad 3 and stitch-bonded. Accordingly, one wire loop 8a is also formed between the second position P2 and the electrode pad 3. Moreover, since reverse wire bonding is used, low-loop bonding can be realized (FIG. 3 (f)).
[0031]
Finally, the fine metal wires 8 are slightly sent out from the capillaries 20, and the fine metal wires 8 are cut using a clamp or the like near the electrode pad 3. Thereafter, the capillary 20 is retracted upward, and one wire bonding connection step is completed (FIG. 3G).
As mentioned above, although one Embodiment of this invention was described, this invention can also be implemented with another form.
For example, in the above-described embodiment, among the two connection portions of the wiring portion 4 and the fine metal wire 8 formed on the substrate 1, the second position P2 is closer to the semiconductor chip 2 than the first position P1. Although the case where it is a far position has been described as an example, the second position P2 may be a position closer to the semiconductor chip 2 than the first position P1, or the first position P1 and the second position The position P2 may be at a position equidistant from the semiconductor chip 2. Moreover, joining of the board | substrate 1 and the metal fine wire 8 is not limited to two places, You may make a joint point into three or more places.
[0032]
In the above embodiment, the example in which the wiring portion 4 is formed on the substrate 1 made of an insulating material has been described. However, a metal substrate such as a lead frame may be applied as the substrate.
In addition, various design changes can be made within the scope of matters described in the claims.
[Brief description of the drawings]
FIG. 1 is a schematic side view of a semiconductor device according to an embodiment of the present invention.
2 is a schematic side view showing manufacturing steps of the semiconductor device of FIG. 1 in order of steps.
FIG. 3 is a schematic side view showing steps subsequent to FIG. 2 in the order of steps.
FIG. 4 is a schematic side view showing a connection structure by a conventional wire bonding method. FIG. 5 is a schematic side view showing a connection structure by a reverse wire bonding method.
FIG. 6 is a cross-sectional view conceptually showing a difference in propagation of bonding power due to a difference in bonding area.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Substrate 2 Semiconductor chip 3 Electrode pad 4 Wiring part 5 Tip part 6 Middle part 7 Termination part 8 Metal thin wire 8a Wire loop 9 Adhesive 20 Capillary

Claims (3)

A substrate,
A semiconductor chip with electrode pads on the surface;
A tip portion ball-bonded to a first position on the substrate, a middle portion stitch-bonded to a second position different from the first position on the substrate, and a stitch on an electrode pad of the semiconductor chip look containing a fine metal wire having a bonded end portion,
The semiconductor device according to claim 1, wherein the second position is farther from the semiconductor chip than the first position . A first step of connecting the tip of the thin metal wire to a first position on the substrate;
After the first step, a second step of connecting the middle part of the fine metal wire to a second position different from the first position on the substrate;
After this second step, seen including a third step of connecting the end portion of the metal thin wire on the electrode pads of the semiconductor chip surface,
The second step includes a step of connecting the intermediate portion of the thin metal wire so that the second position is farther from the semiconductor chip than the first position. Manufacturing method. The first step includes ball bonding in which a spherical portion is formed at a tip portion of the thin metal wire, and the spherical portion is pressed against a first position on the substrate,
The second step includes stitch bonding that presses a middle portion of the fine metal wire to a second position on the substrate,
3. The method of manufacturing a semiconductor device according to claim 2, wherein the third step includes stitch bonding in which a terminal portion of the thin metal wire is pressed onto an electrode pad on the surface of the semiconductor chip.

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