1. Field of the Invention
The present invention relates to a semiconductor device, a wiring substrate, and a method for producing the same.
2. Description of Related Art
The following are the documents 1 and 2 as related art.
[Patent Document 1] Japanese Patent Application Laid-open Publication No. 2006-253315
[Patent Document 2] Japanese Patent Application Laid-open Publication No. 2002-118208
However, in the above described semiconductor device 100, a stress is generated due to the difference in thermal expansion coefficient between the wiring substrate 110 and the semiconductor chip 120. The stress is particularly increased near the outer circumference of the semiconductor 120. As a result, in the portion, peeling tends to be occurred at the interface between the solder resist layer 112 and the under-fill resin 140. In
A semiconductor device has a wiring substrate and a semiconductor chip mounted on the wiring substrate with a conductive bump disposed in between. The device includes: a solder resist layer mounted on the wiring substrate; a stress alleviating portion which is mounted in the area of the solder resist layer opposed to the outer circumference of the semiconductor chip, and is made of a material different from that of the solder resist layer; and an under-fill resin which fills the gap between the wiring substrate and the semiconductor chip. In the device, the stress alleviating portion has a function of alleviating a stress acting on the solder resist layer and the under-fill resin.
In the semiconductor device, the stress alleviating portion is mounted in the area of the solder resist layer opposed to the outer circumference of the semiconductor chip. The stress alleviating portion alleviates a stress acting on the solder resist layer and the under-fill resin. As a result, peeling is hardly occurred at the interface between the solder resist layer and the under-fill resin.
A wiring substrate mounts the semiconductor chip with the conductive bump disposed in between. The substrate includes the solder resist layer, and the stress alleviating portion which is mounted in the area of the solder resist layer opposed to the outer circumference of the semiconductor chip, and is made of a material different from that of the solder resist layer.
In the wiring substrate, the stress alleviating portion is mounted in the area of the solder resist layer opposed to the outer circumference of the semiconductor chip. In the semiconductor device in which the wiring substrate is used, the stress alleviating portion alleviates a stress acting on the solder resist layer and the under-fill resin. As a result, peeling (e.g. peel-off) is hardly occurs at the interface between the solder resist layer and the under-fill resin.
A semiconductor production method includes forming a solder resist layer on a wiring substrate; forming a stress alleviating portion, which is made of a material different from that of the solder resist layer, in the area of the solder resist layer opposed to the outer circumference of a semiconductor chip; mounting the semiconductor chip above the wiring substrate via a conductive bump; and filling the gap between the wiring substrate and the semiconductor chip with an under-fill resin. The stress alleviating portion has a function of alleviating the stress acting on the solder resist layer and the under-fill resin.
In the production method, the stress alleviating portion is formed in the area of the solder resist layer opposed to the outer circumference of the semiconductor chip. The stress alleviating portion alleviates the stress acting on the solder resist layer and the under-fill resin. As a result, in the semiconductor device produced in the method, peeling hardly occurs at the interface between the solder resist layer and the under-fill resin.
A wiring substrate production method includes forming a solder resist layer, and forming a stress alleviating portion, which is made of a material different from that of the solder resist layer, in the area of the solder resist layer opposed to the outer circumference of a semiconductor chip.
In the production method, the stress alleviating portion is formed in the area of the solder resist layer opposed to the outer circumference of the semiconductor chip. In the semiconductor device in which the wiring substrate produced by the method is used, the stress alleviating portion alleviates the stress acting on the solder resist layer and the under-fill resin. As a result, peeling hardly occurs at the interface between the solder resist layer and the under-fill resin.
According to the present invention, a reliable semiconductor device, a reliable wiring substrate, and a method for producing the same are realized.
The above and other exemplary aspects, advantages and features of the present invention will be more apparent from the following description of certain exemplary embodiments taken in conjunction with the accompanying drawings, in which:
The wiring substrate 10 includes a solder resist layer 12, a stress alleviating portion 14, and an electrode pad 16. In the solder resist layer 12, an opening 12a is formed. The opening 12a is located on the electrode pad 16. In the present embodiment, the marginal portions of the electrode pad 16 are covered with the solder resist layer 12. That is, in the wiring substrate 10, SMD (Solder Mask Define) structure is realized. As the material of the solder resist layer 12, for example, epoxy-based resin can be used.
In the area (that is, an area overlapping with the outer circumference in a plan view) of the solder resist layer 12 opposed to the outer circumference of the semiconductor chip 20, the stress alleviating portion 14 is mounted. The stress alleviating portion 14 has a function of alleviating the stress acting on the solder resist layer 12 and the under-fill resin 40. The stress alleviating portion 14 is constructed as a resin layer. The material of the stress alleviating portion 14 is difference from that of the solder resist layer 12. As the material of the stress alleviating portion 14, for example, acryl-based resin, or silicon-based resin can be used. Alternatively, a hybrid resin of epoxy and acryl, or a hybrid resin of epoxy and silicon can be used as the material of the stress alleviating portion 14.
The stress alleviating portion 14 preferably has a lower degree of elasticity than the solder resist layer 12. The values of the degree of elasticity (Young's modulus) of the solder resist layer 12 and the stress alleviating portion 14 are, for example, 3 to 10 GPa and 0.01 to 3 Gpa, respectively.
Returning to
The conductive bump 30 is connected with the electrode pad 16 through the above-described opening 12a. A contacting area between the conductive bump 30 and the electrode pad 16 is approximately equal to the bottom area (the area of the exposed portion of the electrode pad 16) of the opening 12a in the present embodiment. This means that the construction in which the approximate entire of the opening 12a is filled with the conductive bump 30 is formed. As the material of the conductive bump 30, for example, a solder, copper (Cu), or gold (Au) can be used.
Referring to
Then, the stress alleviating portion 14 is formed by patterning the resin 15. That is, the resin 15 is removed except for that located in the area opposed to the semiconductor chip 20. As a result, the wiring substrate 10 is obtained (
Subsequently, the semiconductor 20 is mounted on the wiring substrate 10 with the conductive bump 30 disposed in between (
The advantages of the present embodiment will be described. A stress alleviating portion 14 is mounted in the area of the solder resist layer 12 opposed to the outer circumference of the semiconductor chip 20 in the present embodiment. The stress alleviating portion 14 alleviates the stress acting on the solder resist layer 12 and the under-fill resin 40. As a result, peeling is hardly occurred at the interface between the solder resist layer 12 and the under-fill resin 40.
The stress acting on the conductive bump 30 is also alleviated by the stress alleviating portion 14. Therefore, a reliability of the connection of the conductive bump 30 with the electrode pad 16 is improved. Particularly, when a construction in which the approximate entire of the opening 12a of the solder resist layer 12 is filled with the conductive bump 30 is formed as in the present embodiment, there is little gap between the solder resist layer 12 and the conductive bump 30. As a result, a stress tends to be transmitted from the solder resist layer 12 to the conductive bump 30 as compared to a case where the solder resist layer 12 and the conductive bump 30 are spaced apart from each other. Therefore, when the construction is formed, it is particularly useful to mount the stress alleviating portion 14 to enhance the connection reliability of the conductive bump 30.
Furthermore, the presence of the stress alleviating portion 14 can inhibit the under-fill resin 40 injected in the gap between the wiring substrate 10 and the semiconductor chip 20 from flowing out of the gap. As a result, the filet shape of the under-fill resin 40 can be scaled down.
The stress alleviating portion 14 is constructed as a resin layer. Therefore, the stress alleviating portion 14 can easily be formed. The degree of elasticity of the stress alleviating portion 14 is lower than that of the solder resist layer 12. As a result, an effect of alleviating a stress is further enhanced by the stress alleviating portion 14.
No sharp corner is present in the inner circumference of the stress alleviating portion 14 in a plan view. When a sharp corner is present, a stress is concentrated there. When a stress is concentrated in a particular area in such a manner, a possibility for a crack to be created from the area as a starting point is increased. From this viewpoint, in the present embodiment, no sharp corner is present in the inner circumference of the stress alleviating portion 14. As a result, a stress is diffused. Therefore, a crack can be inhibited from being occurred. Furthermore, no sharp corner is present in the outer circumference of the stress alleviating portion 14, so a crack is further inhibited from being occurred.
In the present embodiment, as described in
Referring to
Thereafter, a resin layer 14b is formed only on the resin layer 14a (
Then, the semiconductor chip 20 is mounted on the wiring substrate 10 with the conductive bump 30 disposed in between (
In the present embodiment, it is intended that, by constructing the stress alleviating portion 14 of a number of resin layers having a different degree of elasticity from each other (resin layers 14a, 14b and 14c), the degree of elasticity of the stress alleviating portion 14 is gradually reduced as the resin layer becomes closer to the semiconductor chip 20. By this method, an effect of alleviating a stress can further be enhanced by the stress alleviating portion 14. Therefore, the peeling at the interface between the solder resist layer 12 and the under-fill resin 40 is effectively inhibited. At the same time, the connection reliability of the conductive bump 30 is further improved. The other advantages of the present embodiment are the same as those in the first embodiment.
Referring to
Then, the resin layer 14a is formed by patterning the resin 15a (
Thereafter, the resin layers 14b and 14c are sequentially formed by the same method as that for resin layer 14a. Furthermore, the semiconductor chip 20 is mounted on the wiring substrate 10 with the conductive bump 30 disposed in between (
In the present embodiment, the top surface of the stress alleviating portion 14 is a rough surface. As a result, the under-fill resin 40 injected in the gap between the wiring substrate 10 and the semiconductor chip 20 can more effectively be inhibited from flowing out of the gap by the stress alleviating portion 14. The interface between the resin layers 14a and 14b is also a rough surface. This roughness allows the improvement in the adhesion between the resin layers 14a and 14b. The same is true in the interface between the resin layers 14b and 14c. The other advantages of the present embodiment are the same as those in the second embodiment.
The present invention is not limited to the embodiments, and allows various modifications. For example, in the embodiments, an example in which the stress alleviating portion 14 is mounted over the entire of the outer circumference of the semiconductor chip 20 is shown. Alternatively, the stress alleviating portion 14 may be mounted over a part of the outer circumference. In this case, as shown in
In the example in
In the embodiments, an example in which the conductive bump 30 is mounted while contacting the solder resist layer 12 is shown. Alternatively, the conductive bump 30 may be mounted while being spaced apart from the solder resist layer 12. That is, a contact area of the conductive bump 30 with the electrode pad 16 may be smaller as compared to the area of the bottom surface of the opening 12a.
In
Further, it is noted that, Applicant's intent is to encompass equivalents of all claim elements, even if amended later during prosecution
Number | Date | Country | Kind |
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2007-043292 | Feb 2007 | JP | national |