The present invention relates to the shape of a semiconductor device, and in particular the present invention relates to restricting an increased profile height due to curvature caused by differences in thermal expansion coefficient among members forming a semiconductor device.
BGA (Ball Grid Array) semiconductor devices are generally constructed in such a way that a semiconductor chip is mounted on one surface of a wiring board, and that surface of the wiring board is covered by a sealing resin so that the semiconductor chip is covered, as described in Patent Document 1, for example.
The wiring board, semiconductor chip and sealing resin forming a semiconductor device normally have different thermal expansion coefficients. Curvature is produced in the semiconductor device due to the difference in thermal expansion coefficients. In a semiconductor device in which convex curvature has been produced, the central part projects from the surrounding part, whereas in a semiconductor device in which concave curvature has been produced, the surrounding part projects from the central part. In either case, the actual semiconductor device which has curved due to the difference in thermal expansion coefficients of the constituent members has regions which project to a greater extent than a semiconductor device in an ideal state without any curvature. The presence of these projections acts in a direction which increases the overall height of the semiconductor device and is a factor in substantially increasing the profile height of the semiconductor device.
There has been a demand for thinner and more compact portable devices etc. in recent years, and the semiconductor devices incorporated in such devices also have to be thinner and more compact. Under these circumstances, if a large amount of curvature is produced in a semiconductor device, the overall height of the semiconductor device after mounting increases and as a result a situation arises in which the semiconductor device can no longer be incorporated into a portable device and the production yield deteriorates.
By making the thermal expansion coefficients of the constituent members of the semiconductor device as close as possible to one another it is possible to restrict the magnitude of curvature to a certain extent. However, there are limits to this and so there are constraints on the combination of materials in semiconductor devices.
Patent Document 2 may be cited as a document describing an invention associated with the present invention. That document describes a technique in which four locations at the corners of a semiconductor device are endowed with a recessed shape in order to prevent cracking and chipping at the corners of the semiconductor device. That document does not take account of curvature of the semiconductor device. Furthermore, a new step is added in that document in order to form recesses in a sealing resin.
Patent Documents 1 and 2 are cited as documents describing technology relating to the present invention.
Patent Document 1: JP 2012-169398 A
Patent Document 2: JP 2002-100702 A
The present invention has been devised in view of the situation described above, and the problem to be solved by the present invention lies in preventing an increased profile height in a semiconductor device as a result of part of the semiconductor device projecting due to shape distortion such as curvature produced in the semiconductor device.
In order to solve the abovementioned problem, one mode of the present invention provides a method for manufacturing a semiconductor device, characterized in that it comprises the following stages: a sample manufacturing stage in which a sample semiconductor device is manufactured; a sample measurement stage in which a measurement value relating to curvature of the sample is taken; a removal region determination stage in which a removal region constituting a region for removal from a sealing resin layer covering one surface of the semiconductor device positioned on the opposite side of a substrate when the semiconductor device is mounted on said substrate is determined in accordance with the measurement value; and a manufacturing stage which is a stage in which the semiconductor device is manufactured, comprising a step in which the sealing resin layer is formed, after which the removal region is removed.
According to the present invention, a removal region including a region projecting from a semiconductor device is determined and removed in accordance with a measurement result of a sample semiconductor device, and therefore it is possible to prevent an increased profile height of the semiconductor device which would occur if a projecting region were left in place.
The method for manufacturing a semiconductor device according to a mode of embodiment of the present invention will be described. According to the inventive manufacturing method, a sample of a semiconductor device is manufactured prior to the manufacture of the semiconductor device serving as the final target product, and the sample is measured in order to acquire measurement values relating to the magnitude and direction of curvature. Curvature causes the surface of the sample semiconductor device mounted on a substrate, to be more specific part of a sealing resin layer, to extend beyond a predetermined reference surface. If the region beyond the reference surface is referred to as a “projecting region”, then according to this method, a region including the projecting region of the sealing resin layer is determined to be a removal region which is removed in the process of manufacturing the semiconductor device serving as the product.
Referring to
The magnitude and direction etc. of the curvature and values relating to the curvature are then measured by actually measuring the sample 1 (step S2).
The projecting region is then obtained in accordance with the measurement values acquired in step S2 and a predetermined reference surface 7 (step S3). The reference surface 7 constitutes, for example, the height of the semiconductor device from the substrate surface when a semiconductor device constituting the final target article is mounted on the substrate using the solder balls. When concave curvature is produced as with the sample 1, the peripheral edges of the sample 1, and in particular the upper sides of the four corners of the sealing resin layer 4 if the sample is rectangular, as shown in
Removal regions 8 are then determined in accordance with the projecting regions 11 (step S4). The shape of the removal regions 8 should include the projecting regions 11. For example, the removal region 8 in
After the removal regions 8 have been determined in this way, the semiconductor device serving as the final product is manufactured. The removal regions 8 are removed in the manufacturing process (step S5).
The abovementioned description relates to a case in which the semiconductor device is curved in a concave shape, but the present invention may equally be applied if the semiconductor device is curved in a convex shape. As shown in
The semiconductor device 40 shown in
As shown in the cross section A-A in
As is clear from
According to Exemplary Embodiment 1, the semiconductor device 40 has concave curvature and the overall height of the semiconductor device can be reduced by forming the first recesses 42a-42d at the highest points on the surface of the sealing resin layer 41, so the overall height after mounting can also be reduced. Furthermore, the amount of curvature can be reduced by reducing the amount of resin at the corners of the sealing resin layer 41. In addition, when the semiconductor device 40 is mass produced, it is possible to restrict fluctuations in curvature among individual semiconductor devices 40. As a result, the incidence of mounting defects when the semiconductor device 40 is incorporated into another device such as a portable information processor can be reduced and the assembly yield can be improved.
It should be noted that the second recess 43 is preferably formed on the surface avoiding positions directly above the wires 51 connecting the semiconductor chip 46 and the wiring board 44, as shown in
As shown in
Unlike the semiconductor device 40, a sealing resin layer is not formed on the semiconductor device 60, so there is less curvature than with the semiconductor device 40. As shown in
The method for manufacturing the semiconductor device 40 will be described next with reference to
A wiring motherboard 70 such as that shown in
An adhesive member 45 is then applied to each of the product formation regions 71 and a semiconductor chip 46 is mounted thereon, as shown in
Next, as shown in
The mark-forming step is carried out next. In the mark-forming step, the surface of the sealing resin layer 75 is marked using a laser marking device, for example, as shown in
A YVO4 (yttrium vanadium oxide) laser is used as the laser for the laser marking device. The resin surface of the sealing resin layer 75 is irradiated with laser light and the resin surface is scraped away by around 5-30 μm; as a result, the unevenness produced by the scraping away produces diffuse reflection and the mark can be identified by the contrast with the molded resin surface. The required recess can be formed in the surface of the sealing resin layer 75 by irradiating the sealing resin layer 75 with laser light through a mask having a predetermined pattern, or by drawing a predetermined pattern on the sealing resin layer 75 using laser light.
As shown in
Furthermore, in the mark-forming step, an identification mark such as a company name or product name etc. is formed as the second recess 43 in each of the plurality of product formation regions 71 on the wiring motherboard 70 at the same time as the first recesses 42 are formed. The second recess 43 is formed by grinding the surface of the sealing resin layer 41 of the individual semiconductor devices 40 by means of laser marking. In view of this, the structure below the second recess 43 is preferably taken into account for determining the position in which the second recess 43 is formed. For example, the second recess 43 is preferably formed to avoid a position above the wires 51 on the surface of the sealing resin layer 41 in order to take account of the fact that the wiring board 44 and the semiconductor chip 46 are connected by wires 51. By this means, the resin surface is ground by means of laser marking, and as a result it is possible to avoid exposure of the wires 51 from the surface of the sealing resin layer 41.
The solder balls 47 are then mounted on the lands 48 on the lower surface of the wiring motherboard 70, as shown in
Finally, in the substrate dicing step, as shown in
As shown in
When concave curvature is produced—with the center of the semiconductor device 40 being depressed and the surrounding part being raised for reasons including the difference in thermal expansion coefficient of the sealing resin layer 41, semiconductor chip 46 and wiring board 44—curvature is produced in such a way that the four corners are the highest when the semiconductor substrate 40 is mounted on a substrate or the like, but the raised portions are ground as the first recesses 42, so it is possible to prevent the overall height of the semiconductor device from increasing due to concave curvature.
Furthermore, the first recesses 42 are formed all together when the second recess 43 is formed in the mark-forming step. The second recess 43, i.e. the identification mark, is formed in a step which is also carried out in the manufacture of a conventional semiconductor device. This means that there is no need to add a new step simply with the aim of forming the first recesses 42, and the first recesses 42 can be formed simply by modifying part of an existing step.
A semiconductor device 80 constituting Exemplary Embodiment 2 of the present invention will be described. In Exemplary Embodiment 1 described above, cylindrical recesses having a quarter of an arc as the bottom surface were formed as the first recesses 42 at the four corners of the surface of the semiconductor device 40 having concave curvature. The semiconductor device 80 according to this exemplary embodiment likewise has concave curvature and corresponds to the sample 1 in the mode of embodiment, but the shape of the first recesses differs.
As shown in
Here, a comparison of
In addition, as will be understood from a comparison of
It should be noted that the method for manufacturing the semiconductor device 80 is substantially the same as the method for manufacturing a semiconductor device 40. In Exemplary Embodiment 1, the semiconductor device 40 was manufactured by forming circular recesses at the intersections of the dicing lines 73, but in Exemplary Embodiment 2, strip-like recesses are formed along the dicing lines 73 and are not limited to the intersections of the dicing lines 73.
A semiconductor device 90 constituting Exemplary Embodiment 3 of the present invention will be described. Exemplary Embodiments 1 and 2 are based on a semiconductor device having concave curvature. In contrast to this, the semiconductor device 90 has convex curvature and corresponds to the sample 20 in the mode of embodiment. The height of the central part of a sealing resin layer 91 is relatively higher because of the convex curvature and the height of the surrounding part is relatively lower.
As shown in
The height of the central portion of the sealing resin layer 91 is, by its nature, the greatest due to convex curvature of the sealing resin layer 91, and as a result the height of the semiconductor device 90 is pushed upward; by forming the first recess 92, it is possible to avoid an increased profile height of the semiconductor device 90 caused by convex curvature.
In the mode of embodiment and the exemplary embodiments described above, a description was given of a semiconductor device having a structure in which a single semiconductor chip is mounted in a single product formation region and covered by a sealing resin layer, but the present invention may equally be applied to a semiconductor device having a structure in which a plurality of semiconductor chips are mounted in a single product formation region and covered by a sealing resin layer. A semiconductor device 100 having a structure in which two semiconductor chips are stacked and mounted in a single product formation region and covered by a sealing resin layer will be described as Exemplary Embodiment 4.
Exemplary Embodiment 4 relates to an example in which the present invention is applied to a semiconductor device having concave curvature in the same way as Exemplary Embodiment 1, but in Exemplary Embodiment 1, a single semiconductor chip 46 is mounted on a wiring board 44, whereas in the semiconductor device 100 according to this exemplary embodiment, an adhesive member 101 is applied to the semiconductor chip 46 and a separate semiconductor chip 102 is further mounted thereon.
The appearance of the semiconductor device 100 when seen from above is no different than the semiconductor device 40 shown in
The invention devised by the present inventor has been described in accordance with exemplary embodiments, but the present invention is not limited to these exemplary embodiments and it goes without saying that various modifications may be made within a scope that does not depart from the essential point of the present invention.
For example, as examples of the removal regions 8 referred to in the mode of embodiment, arc-shaped recesses having a center angle of 90° are formed at the four corners of a semiconductor device by forming circular recesses at intersections of dicing lines and cutting along the dicing lines in a semiconductor device having concave curvature (Exemplary Embodiment 1), strip-like recesses are formed along the four sides of a semiconductor device in such a way as to surround the sides by forming strip-like recesses along dicing lines and cutting along the dicing lines in a semiconductor device likewise having concave curvature (Exemplary Embodiment 2), and a circular recess is formed in substantially the center of a semiconductor device having convex curvature, but the present invention is not limited to these examples. According to one mode of the present invention, when curvature is produced in a semiconductor device because of differences in the thermal expansion coefficients or shapes etc. among the sealing resin layer, semiconductor chip and wiring board, a sample of the semiconductor device is manufactured, the position where the height of the sample is greatest due to curvature is identified, and a portion including that position is ground at the same time as an identification mark is ground, preferably using a laser marking device or the like, and as a result an increased profile height of the semiconductor device which is the final product is prevented. Accordingly, the position in which the first recesses corresponding to the removal regions are formed should include the location or locations which actually have the highest profile when the sample is measured, and the present invention should not be construed as being limited to the shapes or positions described above.
Part or all of the mode of embodiment described above may also be described as in the following additional notes, but the mode of embodiment is not limited thereby.
(Additional Note 1)
A semiconductor device characterized in that it comprises:
a wiring board;
a semiconductor chip mounted on one surface of the wiring board; and
a sealing resin layer formed on said surface of the wiring board in such a way as to cover the semiconductor chip, and
the sealing resin layer has a surface on the opposite side to the wiring board and said surface is curved in a predetermined direction, and
a recess is formed in the region constituting the highest point of said surface which is curved in said predetermined direction.
(Additional Note 2)
The semiconductor device as described in Additional Note 1, characterized in that a surface of the sealing resin layer is curved in a concave manner, and
the recess is formed in the region of an end of said surface of the sealing resin layer.
(Additional Note 3)
The semiconductor device as described in Additional Note 1, characterized in that a surface of the sealing resin layer is curved in a convex manner, and
the recess is formed in a region substantially in the center of said surface of the sealing resin layer.
(Additional Note 4)
The semiconductor device as described in Additional Note 2, characterized in that the recess is formed as a single element along an outer edge of the surface of the sealing resin layer.
(Additional Note 5)
The semiconductor device as described in Additional Note 1, characterized in that a mark is formed on the surface of the sealing resin layer, said mark being formed at a position avoiding the recess.
(Additional Note 6)
The semiconductor device as described in Additional Note 5, characterized in that the wiring board and the semiconductor chip are electrically connected by a plurality of wires, and
the recess and the mark are formed at positions avoiding a region on the surface of the sealing resin layer positioned above the plurality of wires.
(Additional Note 7)
A semiconductor device characterized in that it comprises:
a wiring board;
a semiconductor chip mounted on one surface of the wiring board;
a sealing resin layer formed on said surface of the wiring board in such a way as to cover the semiconductor chip;
a first recess formed on a surface of the sealing resin layer; and
a second recess which is formed on a surface of the sealing resin layer and has a greater depth from the surface than the first recess.
(Additional Note 8)
The semiconductor device as described in Additional Note 7, characterized in that the first recess is formed in a region substantially in the center of said surface of the sealing resin layer, and
the second recess is formed in the region of an end of said surface of the sealing resin layer.
(Additional Note 9)
The semiconductor device as described in Additional Note 7, characterized in that the second recess is formed in a region substantially in the center of said surface of the sealing resin layer, and
the first recess is formed in a different region than the second recess on the surface of the sealing resin layer.
(Additional Note 10)
The semiconductor device as described in Additional Note 8, characterized in that the second recess is formed as a single element along an outer edge of the surface of the sealing resin layer.
(Additional Note 11)
The semiconductor device as described in Additional Note 7, characterized in that the first recess is a mark formed on said surface of the sealing resin layer.
(Additional Note 12)
The semiconductor device as described in Additional Note 7, characterized in that the wiring board and the semiconductor chip are electrically connected by a plurality of wires, and
the first recess and the second recess are formed at positions avoiding a region on the surface of the sealing resin layer positioned above the plurality of wires.
It should be noted that this application claims the benefit of priority based on Japanese Patent Application 2013-9285 filed on Jan. 22, 2013, the disclosure of which is hereby incorporated in its entirety.
Number | Date | Country | Kind |
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2013-009285 | Jan 2013 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2014/050756 | 1/17/2014 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2014/115644 | 7/31/2014 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
6080602 | Tani et al. | Jun 2000 | A |
8632714 | Ogino | Jan 2014 | B2 |
8895326 | Sekiya | Nov 2014 | B2 |
20120251791 | Kawai | Oct 2012 | A1 |
Number | Date | Country |
---|---|---|
2002100702 | Apr 2002 | JP |
2012169398 | Jun 2012 | JP |
Entry |
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Application No. PCT/JP2014/050756, International Search Report, Mar. 18, 2014. |
Number | Date | Country | |
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20150357251 A1 | Dec 2015 | US |