JP2003273147A - Semiconductor device and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To resolve the problem that the strength of a bump base, employing a resin material as a nucleus and covering the whole of the surface of the same by a conductive film, is short whereby breakage occurs in an interface between a projected part 21 composed of resin and a metal film 17 upon connecting the bump base to a circuit board or the like. <P>SOLUTION: A metal film 17 formed on a pad electrode 13 composed of a base metal and on the surface of which a noble metal is arranged is formed with an opening 25 to stably connect the projected part 21 composed of the resin to the pad electrode 13 and ensure the electrical connection between the conductive film 23, formed on the upper layer of the metal film 17 and the pad electrode 13. According to this constitution, the breakage occurring in the interface between the bump base and the metal film is prevented. <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 structure of a semiconductor device and a method of manufacturing the same, and more particularly, to a plurality of pad electrodes formed on a semiconductor substrate and an insulating film exposing the pad electrodes and covering the semiconductor substrate. A metal film which is connected to each pad electrode and serves as a bump underlayer formed on the insulating film, and a protrusion formed of a resin formed on the metal film,
The present invention relates to a structure of a semiconductor device having a conductive film that covers the protrusion and is connected to the metal film, and a method of manufacturing the semiconductor device.

[0002]

2. Description of the Related Art With the demand for miniaturization of electronic equipment, the size of the semiconductor substrate itself has been miniaturized while maintaining its function, and the demand for semiconductor devices having a plurality of pad electrode pitches narrowed has been increasing. In order to narrow the pad electrode pitch, bumps are formed on the pad electrodes of the semiconductor substrate or the electrodes of the circuit board at narrow intervals, and the active substrate surface of the semiconductor substrate faces the circuit board side. Flip-chip method (hereinafter referred to as FC method)
Then, a mounting body having a narrowed electrode pitch is formed by a tape automated bonding method (hereinafter referred to as a TAB method) in which the leads corresponding to the pad electrodes of the semiconductor substrate are collectively connected.

As one of the techniques capable of coping with the narrowed electrode pitch, a resin bump in which a resin material is used as a core and the entire surface thereof is covered with a conductive film has been devised.

Since the resin bump itself has elasticity, the resin bump is resistant to thermal stress. When a thermocompression bonding method is used to connect the semiconductor device to the circuit board, the bumps during use of the semiconductor device may be affected by the temperature difference between the temperature at which the semiconductor device is heated and the room temperature when connecting the semiconductor substrate to the circuit board. Causes thermal stress due to the difference in linear expansion coefficient between the semiconductor substrate and the circuit board. Compared to metal bumps, resin bumps have elasticity and therefore can withstand this thermal stress, and are excellent in long-term reliability as a semiconductor device. Further, even if there is a height variation in the electrodes on the circuit board side, the variation can be complemented by the soft bumps, so that there is an advantage that the circuit board and the semiconductor substrate can be stably connected.

A conventional bump structure and bump manufacturing method will be described below with reference to the sectional view of FIG. In the following description, the case where the semiconductor substrate is connected to the circuit board by the FC method is taken as an example.

As shown in FIG. 3D, the structure of the conventional semiconductor device has a pad electrode 13 on the semiconductor substrate 11, covers the entire surface of the semiconductor substrate 11, and has an opening on the pad electrode 13. The insulating film 15, the metal film 30 that serves as a pad underlayer provided so as to cover the opening of the insulating film 15, the protrusion 21 made of resin provided on the metal film 30, and the surface and the exposed portion of the protrusion 21. And a resin bump 27 formed of a conductive coating 23 provided so as to cover the metal film 30.

Next, a method of manufacturing the bump having the above-described conventional structure will be described with reference to FIGS. First, as shown in FIG. 3A, the insulating film 15 is formed on the entire surface of the semiconductor substrate 11 by opening the pad electrode 13 so that the pad electrode 13 provided on the semiconductor substrate 11 is exposed. As the insulating film 15, a silicon oxide film containing phosphorus, an inorganic film such as a silicon nitride film, an organic polymer film such as a polyimide resin, or a laminated structure of these inorganic film and organic polymer film is used depending on the intended use. Select and form.

Next, as shown in FIG. 3B, a metal film 30 serving as a bump underlayer is formed on the surface of the insulating film 15 including the pad electrode 13. This metal film 30 is formed by forming a metal film on an unnecessary portion by a photolithography method and an etching method after forming the metal film 30 on the surface of the insulating film 15 including the opening on the pad electrode 13 by a sputtering method or a vacuum deposition method. Then, it is formed so as to cover at least the pad electrode 13. Generally, a metal film 3 that serves as a bump base
0 indicates good adhesion to the pad electrode 13 and good electrical conduction, although not clearly shown in the figure, and the first metal layer is further closely adhered to the first metal layer as well as the first metal layer. It is possible to provide a semiconductor device in which the pad electrode 13 and the protruding portion 21 are stably joined by providing the second metal layer having good bonding strength with the protruding portion 21 made of resin.

Subsequently, as shown in FIG. 3C, a protrusion made of resin is formed on the metal film 30. A photosensitive resin is used for the protrusion made of the resin. First, in consideration of the film loss after heat curing of the resin, a photosensitive resin is formed on the entire surface of the semiconductor substrate 11 by a spin coating method so that the projection 21 finally has a desired height. Next, a desired pattern is formed by the photolithography method, and heat treatment is performed to obtain the projection 21 having the desired shape.

Next, as shown in FIG. 3D, the entire exposed surface of the protrusion 21 made of the resin and the metal film 30.
A conductive coating film 23 having a double-layered structure of chromium and gold is formed on the exposed surface of the substrate by a sputtering method, and then is selectively formed only on the protrusions 21 and the metal film 30 by a photolithography method and an etching method. Then, the semiconductor device having the conventional structure in which the resin bumps 27 are mounted is completed.

[0011]

However, if the second metal layer is provided with a layer satisfying only adhesion and conductivity, the following problems will occur.

Here, for example, Cu is added to the second metal layer.
Will be described on the assumption that a polyimide resin is used for the protrusion 21 made of resin. After forming the second metal layer pattern serving as the bump base, polyimide is applied to the entire surface of the semiconductor substrate 11 in a desired thickness in consideration of the film loss after the heat treatment, and the projection 21 pattern having a desired shape is formed by the photolithography method. It is known that a heat treatment performed after this photolithography method forms a reactive organism having a Cu—C—O bond. By this bonding, the protrusion 21 and the second metal layer are surely joined, but this reactive organism is also present on the second metal layer removed by the pattern formation of the protrusion 21. It is formed. The reaction products are difficult to remove by chemical or physical etch methods. Also,
If the conductive coating film 23 is disposed while the reaction product remains on the second metal layer, the electrical conduction between the pad electrode 13 and the conductive coating film 23 will be hindered, and as a result, the resin bump 27 and the circuit. The electrical continuity of the mounting body formed by the substrate and the electrode becomes unstable.

On the other hand, a case in which Au or the like is placed in the second metal layer as a metal which hardly forms an oxide, that is, has a small ionization tendency will be described below. By disposing Au in the second metal layer, it is possible to prevent the second metal layer and the protrusion 21 made of resin from forming a reaction product around the protrusion 21.

However, Au, which is the second metal layer, has a low ionization tendency. In other words, since it is Au that is difficult to oxidize,
It is not possible to join the protrusion 21 made of resin with high adhesion,
If stress is applied to the joint portion from the outside during or after the mounting body is formed, the bump may be broken at the interface between the metal film 30 and the protruding portion 21, and this configuration also has a device reliability aspect. There's a problem.

It is an object of the present invention to solve the above problems and to provide a resin bump having a strong adhesive force at the base of the bump even if a plurality of resin bumps are arranged at a narrow interval while maintaining the function of the conventional resin bump. It is to provide a structure and a method of manufacturing the bump thereof.

[0016]

In order to achieve the above object, the bump structure and bump manufacturing method of the present invention are
Use the method described below.

The semiconductor device of the present invention comprises a plurality of pad electrodes formed on a semiconductor substrate, an insulating film that exposes the pad electrodes and covers the semiconductor substrate, and the insulating film that is connected to each pad electrode. A metal film serving as a bump base formed above, and a protrusion made of resin formed on the metal film,
In a semiconductor device having a conductive film that covers the protrusion and is connected to the metal film, the surface material of the pad electrode is a base metal, and the protrusion and the pad electrode can contact the metal film. Moreover, an opening is formed leaving a connection portion between the metal film and the pad electrode, and a noble metal is arranged as a surface material of the metal film.

In the semiconductor device of the present invention, the noble metal is
It is characterized by being a metal whose main component is any one of gold, silver and platinum group.

According to the method of manufacturing a semiconductor device of the present invention, a plurality of pad electrodes made of a base metal formed on a semiconductor substrate, an insulating film exposing at least a part of the pad electrodes, a protrusion and the pad electrodes are provided. So that they can be joined directly
And a step of forming a metal film having an opening not larger than the size of the pad electrode, which leaves a connection portion between the metal film and the pad electrode, and a protrusion made of resin so as to come into contact with the pad electrode through the opening. A step of forming a portion and a step of forming a conductive film that covers the protrusion and is connected to the metal film.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure and manufacturing method of a semiconductor device of the present invention will be described in detail with reference to the drawings. Figure 1
FIG. 3 is a structural cross-sectional view for explaining the structure of a semiconductor device of the present invention. In the description of the semiconductor device of the present invention, the same components as those used in the prior art will be designated by the same reference numerals.

In the semiconductor device of the present invention, the insulating film 15 having an opening for exposing the pad electrode 13 and the pad electrode 13 are formed on the semiconductor substrate 11 having the pad electrode 13 on the surface of which a base metal is arranged. A metal film 17 serving as a bump base formed by providing the opening 25 so as to be exposed
And a protrusion 21 made of resin formed on the metal film 17 and the metal film 17 exposed on the surface of the protrusion 21 while being directly bonded to the pad electrode 13 through the opening. This is a structure in which the resin bumps 27 on which the conductive film 23 to be covered are formed are arranged.

By adopting this configuration, since the noble metal is used for the surface of the metal film 17 even after the heat treatment of the protrusion 21 made of resin, the noble metal and the protrusion are formed around the protrusion electrode. No reaction product is formed with the resin material. Therefore, the conductive film 23 and the pad electrode 1
The electrical connection with 3 is good. Further, the metal film 17 having the noble metal on the surface does not have good adhesion at a portion in contact with the protrusion 21 made of resin.
A structure is employed in which an opening 25 is provided in the base plate and the projection 21 directly contacts the pad electrode 13 made of a base metal. Therefore, the surface material of the pad electrode 13 made of a base metal is oxidized by the heat treatment in the bump manufacturing process to form a strong bond with the resin material of the protrusion 21, and the base of the resin bump can be made a strong semiconductor device. Therefore, even if a plurality of resin bumps are arranged at narrow intervals, it is possible to obtain a resin bump having a strong adhesion to the bump base.

(Embodiment) A method for manufacturing a semiconductor device of the present invention will be described below with reference to the drawings. 2A to 2D are process cross-sectional views for explaining the method for manufacturing the semiconductor device.

As shown in FIG. 2A, first, a pad electrode 13 is formed on the active element surface of a semiconductor substrate 11 of a silicon wafer by using a material containing aluminum as a base metal as a main component, and at least one of the pad electrodes 13 is formed. An insulating film 15 was formed on the semiconductor substrate 11 having an opening so that the portion was exposed. The material of the insulating film 15 is a silicon nitride film, and the thickness of the silicon nitride film is 1 micron. The silicon nitride film was formed by chemical vapor deposition, and an opening was formed on the pad electrode 13 by photolithography and etching. Then, a metal film 17 was formed on the upper layer to obtain the structure of FIG. The metal film 17 has Cr
And Au have a two-layer laminated structure. Cr and Au are formed by a sputtering method using Ar as a discharge gas, and C
The film thickness of r was 0.05 μm and the film thickness of Au was 0.3 μm.

Then, as shown in FIG. 2B, a resist pattern 19 is formed on the metal film 17. The resist pattern 19 was formed by spin coating, and the resist pattern 19 was formed by photolithography. The resist pattern 19 is the pad electrode 1
The opening 25 is provided on the upper surface of the metal film 3, and the metal film 17 is exposed from the lower side of the resin bump 21 formed in the subsequent step.

Next, as shown in FIG. 2C, unnecessary portions of the pad electrode 13 are exposed from the opening 25 and the metal film 17 is left in contact with the pad electrode 13. The metal film was removed by the etching method. As the etching method, it is preferable to use dry etching which is desirable in terms of dimensional accuracy and reproducibility.

Further, as shown in FIG. 2D, a protrusion 21 made of resin is formed on the pad electrode 13. Here, the protrusions 21 were formed using photosensitive polyimide. First, a photosensitive polyimide is applied to the entire surface of the substrate by using a spin coat method, and a pattern of the protrusions 21 made of the photosensitive polyimide is formed so as to contact the pad electrode 13 by photolithography using a predetermined mask. At this time, the resin bump 21 is completely covered with the metal film 1.
It is necessary to have a shape and a size that do not cover 7 up.

Finally, as shown in FIG.
The conductive film 2 is formed on the surface of the metal film and the exposed portion of the metal film 17.
Place 3 First, as shown in FIG.
In the upper layer of the structure of (d), the surface of the resin bump 21 and the exposed surface of the metal film 17 are Cr, followed by Au.
After the film was formed, a desired pattern was formed by the photolithography method and the etching method to form the conductive film 23.

With this structure, the conductive film 23 and the pad electrode 13 can be reliably connected through the metal film 17, and the resin bump 27 can be reliably fixed on the semiconductor substrate 11.

[0030]

As is apparent from the above description, by using the structure of the semiconductor device of the present invention, the conductive film 23 and the pad electrode 13 made of base metal can be surely connected through the metal film 17, and It was possible to improve the adhesion strength of the resin bump base of the semiconductor device.

Further, if the mounting body is formed using the semiconductor device of the present invention, the bump bases of the semiconductor device are firmly connected even if external stress is applied to the semiconductor device and the circuit board which form the mounting body. Therefore, electrical continuity between the semiconductor device and the circuit board is not hindered, and a highly reliable mounting body can be obtained.

[Brief description of drawings]

FIG. 1 is a structural cross-sectional view showing a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a process sectional view showing the manufacturing method of the semiconductor device in the embodiment of the present invention.

3A to 3D are process cross-sectional views showing a structure and a manufacturing method of a semiconductor device in a conventional technique.

[Explanation of symbols]

11 Semiconductor substrate 13 Pad electrode 15 Insulating film 17 Metal film 19 resist pattern 21 Projection 23 Conductive film 25 openings 27 resin bumps

Claims (3)

[Claims] 1. A plurality of pad electrodes formed on a semiconductor substrate, an insulating film that exposes the pad electrodes to cover the semiconductor substrate, and bumps that are connected to the pad electrodes and are formed on the insulating film. In a semiconductor device having a metal film as a base, a protrusion formed of a resin formed on the metal film, and a conductive film that covers the protrusion and is connected to the metal film, the surface material of the pad electrode is a base metal. An opening is formed in the metal film so that the projection and the pad electrode can contact each other, and a connection portion between the metal film and the pad electrode is left, and a surface material of the metal film. A semiconductor device characterized by arranging a noble metal in the. 2. The semiconductor device according to claim 1, wherein the noble metal is made of a metal containing any one of gold, silver and platinum group as a main component. 3. A plurality of pad electrodes made of a base metal formed on a semiconductor substrate, an insulating film exposing at least a part of the pad electrodes, a protrusion and the pad electrodes can be directly joined, and A step of forming a metal film having an opening size equal to or smaller than the size of the pad electrode, which leaves a connection portion between the metal film and the pad electrode, and a protrusion made of resin so as to come into contact with the pad electrode through the opening part. And a step of forming a conductive film that covers the protrusion and is connected to the metal film.