JPH10294318A - Electronic part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electronic part in which electric short circuit is prevented even in the case of fine pattern connection pitch by an arrangement wherein a metal layer for preventing diffusion of solder comprises a solder bump electrode, a wet region and an unwet region and the central part for at least an opening region comprises a solder bump electrode and a wet region. SOLUTION: An electrode pad 13 is provided on an electronic part 11 comprising a silicon semiconductor and an insulating protective film 12 of silicon nitride is deposited thereon. A first metal layer 14 of titanium for preventing diffusion of solder is formed along the surface of the electrode pad 13 at an opening 18 and the insulating protective film 12 while covering them perfectly and a second metal layer 15 of nickel for preventing diffusion of solder is formed thereon. A solder bump electrode 17 is formed on the second metal layer 15 for preventing diffusion of solder. Since titanium is not wetted but nickel is wetted with molten solder, the solder bump electrode is formed only on the second metal layer for preventing diffusion of solder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component mounted on a circuit board in a face-down manner.

[0002]

2. Description of the Related Art Conventionally, an electronic component such as a semiconductor chip can be mounted on a circuit wiring board at a high density, and even if an electronic component having a large number of input / output electrodes is used, the mounting size becomes large. As a method that can be mounted on a circuit wiring board without disposing, so-called face-down mounting, in which electronic components and connection electrodes made of, for example, solder bump electrodes of the circuit wiring board are arranged to face each other, and these are connected using solder bump electrodes The method is considered effective.

[0003] Among them, a face-down mounting method using a solder bump electrode is described in, for example, "Microelectro.
Nic Packaging Handbook (V
anNostrand Reinhold, 198
9) ”, the self-alignment effect at the time of reflow connection of the solder bump electrode allows a wide allowable range of mounting position shift, and the reliability can be improved by the stress relaxation effect due to the plastic deformation of the solder bump electrode. Therefore, the face-down mounting method has become mainstream.

In the face-down mounting method using the solder bump electrodes, the shape of the solder bump electrodes after the reflow connection has a barrel-like shape with a bulged central portion due to the surface tension of the solder during the reflow connection. In this method, at the time of reflow connection,
In order to prevent the adjacent solder projecting electrodes from contacting each other to cause an electrical short circuit, there is a need for a space between the adjacent solder projecting electrodes. For this reason, in order to secure a sufficient space between the solder bump electrodes, the diameter of the bottom surface of the solder bump electrode on the electronic component needs to be 40% or less of the pitch of the solder bump electrodes. Furthermore, the purpose of preventing the electrode pad material from being diffused into the solder bump electrode and reducing the reliability, and the purpose of ensuring the wettability between the solder bump electrode and the electrode pad, is to reduce the distance between the electrode pad and the solder bump electrode. It was necessary to form a diffusion preventing metal layer made of a material that wets the solder.

On the other hand, in general, it is necessary to conduct an electrical inspection of an electronic component by bringing an electrode probe into contact with an electrode pad in order to inspect non-defective products and evaluate characteristics. The electrode pad size required for the electrical inspection is obtained by adding a positioning error between the electrode probe and the electrode pad to the tip diameter of the electrode probe. Therefore, in order to perform an electrical test using an electrode probe, for electrode pads having a fine pitch, a method of reducing the distance between adjacent electrode pads and increasing the dimensions of the electrode pads as much as possible is used. For example, in an electrode pad for wire bonding having a fine pitch, the electrode pad dimension is about 90 μm for an electrode pad pitch of 100 μm.

However, in the face-down mounting method using the solder bump electrodes, since the entire surface of the opening of the electrode pad is covered with a diffusion preventing metal layer made of a material that wets the solder, the size of the opening of the electrode pad is limited. , Smaller than the dimensions of the bottom surface of the solder bump electrode. For this reason, the electrode pad dimensions are set smaller than the connection pitch. If the electrode pad dimensions are set small, it becomes difficult to perform an electrical inspection using an electrode probe when the connection pitch is reduced. As described above, when the size of the opening of the electrode pad is smaller than the size of the bottom surface of the solder bump electrode, there has been a problem that the connection pitch becomes smaller.

[0007]

As described above, as described above,
In the face-down mounting method using the solder bump electrodes, the diameter of the bottom face of the solder bump electrodes needs to be 40% or less of the pitch of the solder bump electrodes in order to prevent an electrical short circuit between adjacent solder bump electrodes. However, when the opening is made finer with the miniaturization of the connection pitch, an electrical inspection using an electrode probe becomes impossible, and thus there is a problem that the miniaturization of the connection pitch is hindered.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and does not cause an electrical short circuit even when the connection pitch is miniaturized, and facilitates an electrical inspection of a solder bump electrode bonding structure. The purpose is to provide electronic components for.

[0009]

SUMMARY OF THE INVENTION The present invention firstly provides a substrate, an electrode pad provided on the substrate, an insulating protective film provided on the electrode pad and having an opening, In an electronic component comprising a solder diffusion preventing metal layer provided on the electrode pad in the opening and a solder bump electrode provided on the solder diffusion preventing metal layer, the solder diffusion preventing metal layer is An electronic component is provided, comprising: a region that is wet with an electrode; and a region that is not wet with the solder bump electrode, and at least a central portion of the opening region is a region that is wet with the solder bump electrode.

The present invention also provides a substrate, an electrode pad provided on the substrate, an insulating protective film provided on the electrode pad and having an opening, the insulating protective film and an electrode in the opening. In a solder diffusion preventing metal layer provided on a pad, and an electronic component including a solder bump electrode provided on the solder diffusion preventing metal layer, the solder diffusion preventing metal layer has a region wet with the solder bump electrode. An electronic component comprising the solder bump electrode and a non-wetting region, wherein a bottom area of the solder bump electrode is smaller than an area of the opening.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to an electronic component having an electronic circuit, and is particularly characterized by an electrode pad provided on an electronic component substrate, a solder diffusion preventing metal layer, and a solder bump electrode for connection. The electronic component of the present invention is divided into the following two aspects.

According to a first aspect of the present invention, an insulating protective film provided on an electrode pad on a substrate and having an opening, a solder diffusion preventing metal layer provided on the insulating protective film and the electrode pad on the opening. And, in an electronic component having a solder bump electrode provided on the solder diffusion barrier metal layer, the solder diffusion barrier metal layer comprises a solder bump electrode wet area and a solder bump electrode non-wet area, and at least An electronic component including a solder bump electrode and a wetted area at the center of the opening area can be obtained.

According to a second aspect, an insulating protective film provided on an electrode pad on a substrate and having an opening, a solder diffusion preventing metal layer provided on the insulating protective film and the electrode pad on the opening, And an electronic component having a solder projection electrode provided on the solder diffusion prevention metal layer, wherein the solder diffusion prevention metal layer includes a region wet with the solder projection electrode, a region not wet with the solder projection electrode, and An electronic component is obtained in which the bottom area of the protruding electrode is smaller than the area of the opening.

In the electronic component according to the first aspect of the present invention, the surface region of the solder diffusion preventing metal layer has at least a region that is wet with the solder provided in the central region and a region that is wet with the solder provided in the other region. It consists of not getting wet. Thereby, the diameter of the solder bump electrode after reflow becomes equal to the solder wetted area of the solder diffusion preventing metal layer.
In this manner, the diameter of the solder bump electrode can be made smaller than the opening of the insulating protective film.

Further, in the electronic component according to the second aspect of the present invention, the size of the bottom surface of the solder bump electrode is formed smaller than that of the opening of the insulating protective film. According to the electronic components according to the first and second aspects, the interval between the formed solder bump electrodes is sufficiently ensured, and the adjacent solder bump electrodes come into contact with each other at the time of reflow connection, resulting in an electrical short circuit. Can be prevented. Further, since it is difficult to electrically short-circuit, in this electronic component, even when the pitch of the solder bump electrodes is fine, the dimensions of the electrode pads can be set sufficiently large. For this reason, the electrical inspection by the electrode probe can be easily performed in the process before the formation of the solder bump electrode and in the process immediately before the reflow of the solder bump electrode. As described above, according to the present invention, it is possible to achieve both miniaturization of the solder bump electrodes and maximization of the electrode pad size, which have been difficult in the past.

According to a first preferred embodiment of the present invention, an insulating protective film having a plurality of electrode pads arranged on a substrate at a predetermined pitch and having openings on each electrode pad, A solder diffusion preventing metal layer is provided on the film and the electrode pad in the opening, and a solder bump electrode is provided on the solder diffusion preventing metal layer. The solder diffusion preventing metal layer is provided on the insulating protective film and the electrode pad in the opening. A first solder diffusion preventing metal layer that does not wet the solder bump electrode, and a first solder diffusion preventing metal layer that is formed on a region including a central portion thereof and excluding at least a region adjacent to the solder bump electrode. There is provided an electronic component including the solder bump electrode thus formed and the wetted second solder diffusion preventing metal layer.

According to a second preferred embodiment of the present invention, an insulating protective film having a plurality of electrode pads arranged at a predetermined pitch on a substrate and having openings on each electrode pad, A solder diffusion preventing metal layer is provided on the film and the electrode pad of the opening, and a solder bump electrode is provided on the solder diffusion preventing metal layer. A second solder diffusion preventing metal layer, which is provided on the insulating protection film and the electrode pad in the opening and wets the solder bump electrode, and a central portion of the second solder diffusion preventing metal layer. And an electronic component comprising a solder bump electrode formed at least on a region adjacent to the solder bump electrode and a non-wetting first solder diffusion preventing metal layer.

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic cross-sectional view illustrating an example of the solder bump electrode structure of the electronic component of the present invention. As shown, the electronic component has an electronic component 11 made of a silicon semiconductor. On the electronic component 11, for example, a thickness of 600 nm, 80
An electrode pad 13 made of a regular octagonal aluminum having a diameter of μm is provided.
An insulating protective film 12 made of, for example, silicon nitride having a thickness of 1200 nm and having a regular octagonal opening 18 having a diameter of 2 μm is formed. Further, the electrode pad 13 in the opening 18
A first solder diffusion preventing metal layer 14 made of regular octagonal titanium having a thickness of, for example, 80 nm and a diameter of 35 μm is formed on the insulating protective film 12 so as to completely cover them along the surface thereof. A second solder diffusion prevention metal layer 15 made of regular octagonal nickel having a thickness of 800 nm and a diameter of 35 μm is formed. Second solder diffusion preventing metal layer 15
On top, the weight ratio of tin to lead is 63:37 and the height is 40
The solder bump electrode 17 having a maximum diameter of 50 μm is formed. Since the first solder diffusion preventing metal layer, titanium, does not wet with the molten solder, and the second solder diffusion preventing metal layer, nickel, has the property of getting wet with the solder. It is formed only on the diffusion preventing metal layer. The pitch of the solder bump electrodes is 90 μm.

FIG. 2 is a top view of the electronic component of the present invention before solder bump electrodes are formed. As shown in the drawing, in the electronic component of the present invention, the region where the solder diffusion preventing metal layer is formed is not wet by the solder by the first solder diffusion preventing metal layer 14 and the second solder diffusion preventing metal layer 15. It is divided into a region and a region that is wet with solder.

Electronic component 1 having a structure as shown in FIG.
Reference numeral 1 denotes a high-frequency component that operates at 1 GHz to 6 GHz. Since the variation in electrical characteristics cannot be ignored in terms of function, inspection of electrical characteristics during the manufacturing process or at the time of completion is indispensable.

FIG. 3 is a schematic sectional view showing a state before the formation of the solder diffusion preventing metal layer of the electronic component of the present invention. As shown in the figure, in this electronic component, the diameter of the opening is 72 μm.
Since it is large, the probing inspection can be easily performed. Also, after the reflow of the solder bump electrodes, as shown in FIG. 1, the distance between the adjacent solder bump electrodes is about half of the pitch of the solder bump electrodes. Never do.

For comparison, FIG. 4 is a schematic sectional view showing an example of an electronic component in which the entire solder diffusion preventing metal layer is easily wetted by solder. In this comparative example, a solder diffusion preventing metal layer 30 that is easily wetted by solder is formed along the surfaces of the electrode pad 33 and the insulating protective film 32 in the opening 39 so as to completely cover them. An example of an electronic component in which solder bump electrodes 37 are formed at a pitch is shown. In this case, since the entire solder diffusion preventing metal layer 20 is easily wetted by the solder, the diameter of the bottom surface of the solder bump electrode 37 is larger than the diameter of the opening 39. Therefore, in order to form the solder bumps 37 at the same pitch as in FIG. 1, the diameter of the opening 19 must be reduced to 25 μm. FIG. 5 is a schematic sectional view showing a state before the formation of the solder diffusion preventing metal layer in FIG. FIG.
As shown in the figure, if the opening 39 is small, the probing electrical inspection is very difficult.

Next, a process for forming an example of the solder bump electrode structure of the electronic component of the present invention will be described with reference to FIGS. FIG. 6 shows an electronic component 11 made of a silicon semiconductor having an electrode pad 13 and an insulating film protective film 12 having an opening 18. In this state, an electrode probe is brought into contact with the electrode pad 13 to perform an electrical test.

Thereafter, as shown in FIG.
A first solder diffusion preventing metal layer 14 made of titanium and a second solder diffusion preventing metal layer 15 made of nickel having a thickness of 800 nm are continuously formed by magnetron sputtering.

Next, a plating resist 21 is applied to form a resist opening 22 in a portion where a solder bump electrode is to be formed. FIG. 8 shows the structure after the formation of the resist opening. As the plating resist, a positive photosensitive resist is used, the resist thickness is 40 μm, and the resist opening 22 is a regular octagon having a diameter of 35 μm.

Next, as shown in FIG. 9, a solder layer 23 having a weight ratio of tin to lead of 63:37 is formed in the resist opening 22 by electroplating. The first and second solder diffusion preventing metal layers 14 and 15 are used as the current-carrying electrodes. The plating thickness is 35 μm.

Next, the plating resist is removed using a resist stripper, and as shown in FIG. 10, the exposed portion of the second solder diffusion preventing metal layer 15 is formed using a dedicated etching solution using the solder layer 23 as a mask. To remove by etching.

As a result, as shown in FIG.
The solder diffusion preventing metal layer 15 remains only under the solder layer 23. Thereafter, as shown in FIG. 12, an etching resist 25 is formed so as to cover the solder layer 23, and using this as a mask, the exposed portion of the first solder diffusion preventing metal layer is patterned by etching. As the etching resist 25, a positive photosensitive resist is used, and the resist thickness is 40 μm.
m. The first solder diffusion preventing metal layer 14 after patterning has a structure that completely covers the opening 18.

Next, the etching resist is removed, and as shown in FIG.
The temperature of the solder protruding electrode 1
7 is formed.

Through the above steps, the first embodiment of the solder bump electrode structure of the electronic component shown in FIG. 1 can be realized. Next, FIG. 14 is a schematic sectional view showing another example of the solder bump electrode structure of the electronic component of the present invention. As shown
This electronic component is an electronic component 11 made of a silicon semiconductor.
Having. On the electronic component 11, for example, a thickness of 600 n
An electrode pad 13 made of regular octagonal aluminum having a diameter of 80 μm and 80 μm, and an insulating protection film 12 made of silicon nitride having a thickness of 1200 nm and having a regular octagonal opening 18 having a diameter of 72 μm are formed. Further, the opening 1
8 having a thickness of 60 nm so as to completely cover them along the surface of the electrode pad 13 and the insulating protective film 12, for example.
An adhesion metal layer 46 made of titanium and a thickness of 800 nm,
A second solder diffusion preventing metal layer 45 made of regular octagonal nickel having a diameter of 80 μm is sequentially formed. On the second solder diffusion preventing metal layer 45, the weight ratio of tin to lead is 63: 3.
7, a solder bump electrode 47 having a height of 40 μm and a maximum diameter of 50 μm is formed. The diameter of the bottom surface of the solder projection electrode 47 is a regular octagon with a diameter of 35 μm, which is smaller than the opening 18. A first solder diffusion preventing metal layer 44 made of 60 nm thick solder and non-wetting titanium is formed on a portion of the second solder diffusion preventing metal layer 45 other than the bottom surface of the solder bump electrode. Since the first solder diffusion preventing metal layer 44 does not wet with the solder and the second solder diffusion preventing metal layer 45 wets with the solder, the solder bump electrode 47 is formed on the first solder diffusion preventing metal layer 45 on the first solder diffusion preventing metal layer 45. It is formed only on the portion where the solder diffusion preventing metal layer 44 is not formed. The pitch of the solder bump electrodes is 90 μm.

This solder bump electrode structure also has a large diameter of the opening 18 of 72 μm as in the example shown in FIG.
In the process before the formation of the solder bump electrodes, the probing inspection can be easily performed. Also, after reflow of the solder bump electrodes, the spacing between the adjacent solder bump electrodes is about half of the pitch of the solder bump electrodes, and is sufficiently large. Absent.

Next, a process for forming another example of the solder bump electrode structure of the electronic component of the present invention will be described with reference to FIGS.
9 will be described. As shown in FIG. 15, an adhesive metal layer 46 made of titanium, a second solder diffusion preventing metal layer 45 made of nickel, and a first solder diffusion preventing metal layer 44 made of titanium are formed on an electronic component 11 made of a silicon semiconductor. Is continuously formed by magnetron sputtering.

Next, as shown in FIG. 16, the first solder diffusion preventing metal layer 44 is patterned by an etching solution by a photo etching process using a photosensitive resist.

Thereafter, as shown in FIG.
Using a μm plating resist layer 41, a resist opening is formed in the portion where the solder bump electrode is to be formed. Further, a solder layer 53 having a weight ratio of tin to lead of 63:37 is formed in the resist opening by electroplating. At this time, the first solder diffusion preventing metal layer 44 and the adhesive metal layer 4
6 is used. The plating thickness is 25 μm.

Next, as shown in FIG. 18, the plating resist is removed by using a resist stripper, and the second solder diffusion preventing metal layer is formed by using the solder layer and the first solder diffusion preventing metal layer 44 as a mask. The exposed portions of the adhesive metal layer 45 and the adhesive metal layer 46 are removed by etching using respective dedicated etching solutions, and are patterned.

Finally, as shown in FIG.
Is heated to 240 ° C. in a nitrogen atmosphere and reflowed to form solder bump electrodes 47. Through the above steps, the solder bump electrode structure of the electronic component shown in FIG. 14 can be realized.

In the above-mentioned example, the solder wetted area of the solder diffusion preventing metal layer area is near the center of the area.
There is an area that is not wet by solder at the periphery. However, in the present invention, without being limited to such a configuration,
In the solder bump electrode structure arranged at a predetermined pitch,
The regions that are not wet by the solder are preferably provided at least in regions adjacent to each other. This indicates that, in the solder diffusion preventing metal layer region, a region that is not adjacent to another solder bump electrode may be provided with a region that is wet with solder.

[0038]

As described above, according to the solder bump electrode structure of the electronic component of the present invention, even if the solder bump electrodes are miniaturized, an electric short circuit between adjacent solder bump electrodes does not occur. Electrical inspection using an electrode probe can be easily performed even on an electrode pad having a fine pitch, and an electrical component having a solder bump electrode can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating an example of a solder bump electrode structure of an electronic component of the present invention.

FIG. 2 is a top view of the electronic component of the present invention before solder bump electrodes are formed.

FIG. 3 is a schematic cross-sectional view showing a state before a solder diffusion preventing metal layer is formed on the electronic component of FIG. 1;

FIG. 4 is a schematic cross-sectional view illustrating an example of an electronic component in which the entire solder diffusion preventing metal layer is easily wetted by solder.

5 is a schematic cross-sectional view showing a state before the formation of a solder diffusion preventing metal layer of the electronic component of FIG. 4;

FIG. 6 is a view for explaining a step of forming an example of a solder bump electrode structure of the electronic component of the present invention.

FIG. 7 is a view for explaining a step of forming an example of a solder bump electrode structure of an electronic component according to the present invention.

FIG. 8 is a view for explaining a step of forming an example of a solder bump electrode structure of an electronic component according to the present invention.

FIG. 9 is a view for explaining a step of forming an example of a solder bump electrode structure of the electronic component of the present invention.

FIG. 10 is a view for explaining a step of forming an example of a solder bump electrode structure of the electronic component of the present invention.

FIG. 11 is a view for explaining a step of forming an example of a solder bump electrode structure of the electronic component of the present invention.

FIG. 12 is a view for explaining a step of forming an example of a solder bump electrode structure of an electronic component according to the present invention.

FIG. 13 is a view for explaining a step of forming an example of the solder bump electrode structure of the electronic component of the present invention.

FIG. 14 is a schematic cross-sectional view illustrating another example of the solder bump electrode structure of the electronic component of the present invention.

FIG. 15 is a view for explaining a step of forming another example of the solder bump electrode structure of the electronic component of the present invention.

FIG. 16 is a view for explaining a step of forming another example of the solder bump electrode structure of the electronic component of the present invention.

FIG. 17 is a view for explaining a step of forming another example of the solder bump electrode structure of the electronic component of the present invention.

FIG. 18 is a view for explaining a step of forming another example of the solder bump electrode structure of the electronic component of the present invention.

FIG. 19 is a view for explaining a step of forming another example of the solder bump electrode structure of the electronic component of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Electronic component 12 ... Insulation protective film 13, 39 ... Electrode pad 14, 44 ... 1st solder diffusion prevention metal layer 15, 45 ... 2nd solder diffusion prevention metal layer 17, 37, 47 ... Solder projection electrode 18 ... Openings 21, 41: Plating resist 22: Resist opening 23, 53 ... Solder layer 25: Etching resist 30: Solder diffusion preventing metal layer 46: Adhesive metal layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ayako Takagi 33, Shinisogocho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Inside Toshiba Production Technology Research Institute Co., Ltd. (72) Inventor Hiroshi Yamada 33, Shinisogocho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Address: Toshiba Production Technology Laboratory Co., Ltd. (72) Inventor: Takeshi Miyagi 33, Shinisogo-cho, Isogo-ku, Yokohama-shi, Kanagawa Pref.

Claims (4)

[Claims] 1. A substrate, an electrode pad provided on the substrate, an insulating protective film provided on the electrode pad and having an opening, and a solder provided on the insulating protective film and the electrode pad in the opening. In an electronic component having a diffusion prevention metal layer and a solder bump electrode provided on the solder diffusion prevention metal layer, the solder diffusion prevention metal layer does not wet the solder bump electrode and a region wet with the solder bump electrode. An electronic component, wherein at least a central portion of the opening region is a region wetted with the solder bump electrode. 2. A substrate, an electrode pad provided on the substrate, an insulating protective film provided on the electrode pad and having an opening, and provided on the insulating protective film and the electrode pad in the opening. In a solder diffusion preventing metal layer, and an electronic component including a solder bump electrode provided on the solder diffusion preventing metal layer, the solder diffusion preventing metal layer has a region wetted with the solder bump electrode, and the solder bump electrode. An electronic component comprising a non-wetting area and a bottom area of the solder bump electrode being smaller than an area of the opening. 3. The solder bump electrodes are arranged at a predetermined pitch, and the solder diffusion preventing metal layer is a first bump that does not wet the solder bump electrodes provided on the insulating protective film and the electrode pads in the openings. And a second solder diffusion preventing metal layer wetted with the solder bump electrode formed at the center of the opening area of the first solder diffusion preventing metal layer. The electronic component according to claim 1. 4. The solder bump electrode is arranged at a predetermined pitch, and the solder diffusion preventing metal layer is wetted by a solder bump electrode provided on the insulating protective film and the electrode pad in the opening. A solder diffusion preventing metal layer and a first solder diffusion preventing metal layer which is not wetted with the solder bump electrodes formed in the second solder diffusion preventing metal layer except for a central portion of the opening region. The electronic component according to claim 1, wherein: