Patent Application
20150170988
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2013-258660, filed Dec. 13, 2013, the entire contents of which are incorporated herein by reference.
Embodiments described herein relate generally to a method of manufacturing a semiconductor apparatus.
Recently, in portable wireless communication apparatuses such as cellular phones, suppression or avoidance of electromagnetic noise generated from embedded electronic components is required to avoid interference with a wireless system. Therefore, shielding of the electronic component which is a noise source has been studied. As a measure thereof, providing a shield layer by using a metal film on a surface of a semiconductor package sealed with a resin has been developed. But there remains the issue of the shield layer having satisfactory adhesive properties with the surface of the sealing resin formed over the embedded electronic component of the device.
The embodiment provides a method of manufacturing a semiconductor apparatus including satisfactory adhesive properties on a resin surface thereof for secure attachment of a shield layer thereover.
In general, according to one embodiment, a plurality of semiconductor devices are mounted on a surface of a wiring substrate and the plurality of semiconductor devices are sealed with a sealing resin formed thereover. The wiring substrates and resin sealing layer thereon is cut and thus separated into individual semiconductor apparatuses, and thereafter the individual semiconductor apparatuses are heated. A shield layer is then formed, by metal sputtering, on the edge portion of the cut wiring substrate and the surfaces of the sealing resin of the semiconductor apparatus after the heating is performed.
Hereinafter, exemplary embodiments are described with reference to the drawings. Further, indicating directions of upper, lower, left, and right directions in the embodiments and the drawings indicate relative directions when a surface on which external elements of a semiconductor apparatus are provided is set to be the bottom, and thus the descriptions of the directions may be different from directions of an actual device. In addition, for the convenience of explanation, the aspect ratios of the features illustrated in the drawings may be different from the aspect ratio thereof in an actual device.
A semiconductor apparatus 10 illustrated in
All of the plurality of semiconductor devices 1a, 1b, 1c, to 1h are formed on and/or in semiconductor substrates such as silicon substrates. Meanwhile, the wiring substrate 2 is a multilayer wiring substrate composed of, for example, a resin substrate, a ceramic substrate, and a glass substrate, as a material of an insulating substrate. A general multilayer copper clad laminated sheet (multilayer printed wiring board) or the like may be used as the wiring substrate 2 to which a resin substrate is applied. The number of the wiring layers may be plural, that is, a multilayer copper clad laminated sheet including two or more (for example, 2, 3, or 4) wiring layers may be used. Further,
The external electrodes 3 are arranged in a lattice (grid array) on the undersurface of the wiring substrate 2. Although
In addition, a surface wiring layer 2a including a signal pattern and a ground pattern is provided on the top surface of the wiring substrate 2, and each of the semiconductor devices 1a, 1b, 1c, to 1h are connected to the signal pattern and the ground pattern through a signal line wire 4 and a ground wire 5, respectively. Furthermore, the surface wiring layer 2a including the signal pattern and the ground pattern and an inter-layer wiring layer 2b connected to the electrode pad on the external electrode 3 side are provided within the wiring substrate 2. Here, a pattern (for example, the ground pattern) of the inter-layer wiring layer 2b which is electrically connected to the shield layer extends to the side (exposed edge) surface of the wiring substrate 2. Also, a pattern from the surface wiring layer 2a which is electrically connected to the shield layer also extends to the side (exposed edge) surface of the wiring substrate 2.
A mold resin 6 is molded on the top surface of the wiring substrate 2 on which the plurality of semiconductor devices 1a, 1b, 1c, to 1h are mounted so as to coat the semiconductor devices 1a, 1b, 1c, to 1h, the surface wiring layer 2a provided on the top surface of the wiring substrate 2, and the signal line wire 4 and the ground wire 5 that connect the semiconductor devices 1a, 1b, 1c, to 1h with the surface wiring layer 2a. The mold resin 6 forms an insulating layer by sealing the semiconductor devices 1a, 1b, 1c, to 1h, the surface wiring layer 2a, the signal line wire 4, the ground wire 5, and any other component on the wiring substrate 2, and any exposed portions on the wiring layer 2a side of the wiring substrate. For example, an epoxy resin including filler such as silica may be used as the mold resin 6.
Product information such as the product number, the year of manufacture, and the manufacturing plant where the apparatus 10 was manufactured is engraved into the top surface of the mold resin 6 by irradiation thereof with a laser. Here, in
The metal material that forms the shield layer 8 is not particularly limited, and for example, Cu, Ni, Cr, B, or a Ni alloy containing Co or W is used. In addition, the shield layer 8 may be a single layer or a stacked structure having multiple layers (for example, a Cu/Ni alloy or a Cu/SUS alloy, starting with copper at the mold resin 6 side of the shield layer 8).
Furthermore, the thickness of the shield layer 8 is not particularly limited, but in order to reduce the size and the thickness of the semiconductor apparatus 10, it is preferable to form the shield layer 8 as thin as possible, so long as it is continuous over the mold resin 6 and the edges of the wiring substrate 2. It is possible to enhance the visibility of the marking section 7 by providing a thin shield layer 8. That is, if the shield layer 8 is thickened, the depth of the engraving by the laser irradiation showing therethrough is decreased so that the visibility thereof is deteriorated. The deterioration of the visibility may be prevented by thinning the shield layer 8. However, if the shield layer 8 is too thin, the mechanical strength of the shield layer 8 is decreased, a portion of the shield layer 8 may peel off and thus the shielding property may be decreased. In view of the above, the shield layer 8 is preferably in the range of 0.1 μm to 8 μm.
According to the present embodiment, the depth of the engraving of the marking section 7 into the mold resin 8 is about 30 μm, and the shield layer 6 has a two-layer structure of a Cu layer having a thickness of 0.1 μm to 6.0 μm on the surface of the mold resin 8 and an SUS (stainless steel) layer having a thickness of 0.1 μm to 1.5 μm thereover. The connection resistance, with a cross section of the pattern electrically connected to the shield layer, may be suppressed by having the surface side of the mold resin 6 in direct contact with the Cu layer. The corrosion resistance, and visibility of the marking section 7 formed in the shield layer 8 may be enhanced by providing the SUS layer over the Cu layer.
Further, for the marking of the mold resin to form the marking section 7 by a laser, a YAG laser, a YVO4 (Yttrium Vanadate) laser or the like preferably forms and obtains the engraving having a small spot diameter and a depth of about 30 μm. According to the present embodiment, the YAG laser having a spot diameter of 0.1 mm is used.
Since the shield layer 8 is formed by metal sputtering on the surface of the mold resin 6 on which the marking section 7 was formed by the laser irradiation in the semiconductor apparatus according to the present embodiment, an increase in the size and the thickness of the apparatus is suppressed and the marking section 7 has excellent visibility and a highly reliable electromagnetic shielding property is provided.
Subsequently, an example of a method of manufacturing the semiconductor apparatus 10 according to the embodiment is described with reference to the flowchart illustrated in
As illustrated in
First, in the manufacturing of the aggregate substrate in Step 101, the aggregate substrate having a structure in which the plurality of wiring substrates 2 are consecutively connected in a matrix shape is manufactured.
Subsequently, in the mounting of the semiconductor devices in Step 102, the semiconductor devices 1a, 1b, 1c, to ih are sequentially stacked on the top surface of each wiring substrate, and also the signal pattern and the ground pattern provided on the wiring substrate 2 are connected to each of the semiconductor devices 1a, 1b, 1c, to 1h respectively through the signal line wire 4 and the ground wire 5.
Subsequently, to seal with a mold resin in Step 103, the mold resin 6, for example, an epoxy resin is molded over the top surface side of the aggregate substrate (the wiring substrate from which individual apparatuses will be cut) on which the semiconductor devices 1a, 1b, 1c, to 1h are mounted so that the semiconductor devices 1a, 1b, 1c, to 1h are sealed therein. A molding method such as a transfer molding method, a compression molding method, or an injection molding method may be used for the molding of the mold resin 6.
Subsequently, in the separation process in Step 104, in order to manufacture the respective semiconductor apparatuses 10, the mold resin 6 is cut together with the aggregate substrate to form the wiring substrates 2 on which the semiconductor devices 1a, 1b, 1c, to 1h are mounted. A blade such as a diamond blade may be used for the cutting. Further, when performing the cutting, pure water in which carbon dioxide gas is dissolved is supplied to a contact portion between the blade and the mold resin 6 or the aggregate substrate. This is performed in order to cool the blade and the mold resin 6 and the aggregate substrate, suppress the scattering of dust generated during the cutting, and reduce static charge generated during the cutting.
Subsequently, in the marking process in Step 105, product information such as the product name, the product number, the year of manufacture, and the manufacturing plant of manufacture of the device is engraved on the top surface of the mold resin 6 by irradiation with a laser by a laser marking apparatus including a YAG laser or the like. In view of the satisfactory visibility and workability, the depth of the engraving is preferably in the range of about 20 μm to 40 μm, more preferably in the range of about 25 μm to 35 μm, and most preferably in the range of about 30 μm.
Subsequently, in the baking process in Step 106, each of the semiconductor apparatuses 10 is heated (baked). In the separation process, since each of semiconductor apparatuses 10 is cleansed with pure water, the mold resin 6 or the wiring substrate 2 may be in a state in which moisture is absorbed therein or adhered thereto. If the mold resin 6 or the wiring substrate 2 is subjected to metal sputtering with moisture absorbed therein or adhered thereto, the sputtered metal layer may peel off from portions of the mold resin 6 or the wiring substrate 2. In order to suppress such peeling, before performing the metal sputtering of the shield layer 8 onto the mold resin 6, each of the semiconductor apparatuses 10 is baked for a predetermined time at a temperature of the boiling point of water or higher to cause the moisture absorption of the mold resin 6 or the wiring substrate 2 to be decreased.
As a result of cutting in the separation process in Step 104, the cross section of the line pattern which will be electrically connected to the shield layer to connect the shield layer 8 to a ground terminal of the device is exposed at the side (edge) surfaces of the wiring substrate 2. In the baking process in Step 106, if each of the semiconductor apparatuses 10 is held for a predetermined time at a temperature of the boiling point of water or higher (for example, 100° C. or higher in 1 atm), the exposed portion of the wiring pattern may be oxidized by the resin baking, and the contact resistance between the shield layer 8 and the wiring pattern electrically connected to the shield layer 8 will be relatively high.
Therefore, in the baking process in Step 106, in order to suppress the oxidization of the exposed portion of the wiring pattern, each of the semiconductor apparatuses 10 is held in a heated environment having an oxygen concentration lower than an ambient atmospheric oxygen concentration. For example, each of the semiconductor apparatuses 10 is heated in a thermostatic chamber (Anaerobic Temperature Oven) that is heated above the boiling point of water while purging the inside of the chamber with an inert gas (N2, CO2, or the like).
Specifically, an oxygen concentration in the oven, lower than the ambient atmospheric oxygen concentration, is preferably 1.0% or lower. As a result, the thickness of any oxidized film in the exposed portion of the pattern electrically connected to the shield layer 8 is less than 50 nm, which is required to properly connect the shield layer 8 to the wiring pattern and thus to ground and result in the desired electromagnetic shielding properties therefrom.
Subsequently, in the forming of the shield layer 8 by metal sputtering in Step 107, metal is sputtered onto the entire surface of the mold resin 6 on which the laser marking was performed, that is, all of the top surface and the side surfaces including the side surface (edges) of the exposed substrate 2, so that a shield layer 8 having a thickness of, for example, 3 μm is formed, forming a layer that conformally follows the contours of the laser marking and yielding the semiconductor apparatus 10 as illustrated in
Further, when the metal sputtering is performed, it is preferable to roughen the surface, at least the top surface, of the mold resin 6, in advance to enhance the adhesive property of the shield layer 8 to the mold resin 6. In the present method, the mold resin sealing a number of underlying semiconductor apparatuses is cut in order to obtain multiple individual semiconductor apparatuses. Accordingly, since the side surface of the mold resin 6 is roughened by the cutting, an additional roughening of the mold resin 6 may not be required, but an additional roughening process may be added, if necessary. To further roughen the resin mold 6 surface, reverse sputtering (sputter etching) may be employed, i.e., before sputtering the metal layer, the surface of the resin mold 6 is sputtered by ions of the sputtering plasma, by negatively biasing the support on which the resin mold 6 and underlying substrate 2 are supported in the sputtering apparatus. If reverse sputtering is performed, it is not required to use another, for example a dedicated, etching apparatus to perform the roughening, but such a separate etching apparatus could be employed to sputter etch the resin mold 6 surface. In addition, since the roughening may be performed by using the same chamber as in the metal sputtering, the processes may be simplified and the processing time may be shortened. Therefore, roughening the surface of the resin mold by reverse sputtering is preferable.
Thereafter, in the inspection process in Step 108, the resistance value between the pattern electrically connected to the manufactured shield layer 8 of the semiconductor apparatus 10 and the shield layer 8 is measured. In the inspection process in Step 108, it is confirmed that there is no issue in the shielding property of the shield layer 8, i.e., the shield layer is adequately connected to the ground terminal, based on the resistance value.
In the inspection process in step 108, the electrical resistance between the external electrode 3a for measurement and the portion of the general external electrode 3b connected to the wiring pattern electrically connected to the shield layer 8 is measured.
Further, in the present embodiment, a pad formed of the electrode film formed on the underside of the substrate 2 is used as the external electrode 3a for the measurement, and a bump electrode is used for the general external electrode 3b.
According to the aforementioned manufacture method of the semiconductor apparatus, since the shield layer is formed of sputtered metal, an extremely thin shield layer may be formed thereof, and the addition to the size and the thickness of the semiconductor apparatus may be minimized.
In addition, after the separation into respective semiconductor packages, the semiconductor apparatus 10 is heated before the metal sputtering. Accordingly, the sputtered metal layer may be suppressed from being peeled off, and a semiconductor having a good yield rate or yield percentage may be manufactured. Here, the heating of the semiconductor apparatus 10 before metal sputtering performed in an atmosphere having an oxygen concentration lower than the atmospheric oxygen concentration. Accordingly, the oxidization, or excess oxidation of the exposed surface of the pattern to be electrically connected to the shield layer 8 may be suppressed. As a result, the electrical resistance between the pattern electrically connected to the shield layer 8 and the shield layer 8 may be suppressed to be low.
Furthermore, after the product information or the like is marked into the surface of the mold resin 6 by the laser, the shield layer 8 is formed. Accordingly, a highly reliable shielding property may be obtained and also a marking section having sufficient visibility may be formed. That is, when laser marking is performed after forming the shield layer, the shield layer may be penetrated by the laser, and the shielding properties thereof may be decreased. In addition, if the shielding layer is not penetrated during marking, the engraving is shallow visibility thereof may not result. Since the shield layer is formed after the laser marking in the method of manufacturing the semiconductor apparatus, the shield layer may not be penetrated, and the engraving having a sufficient depth may be obtained. Accordingly, a highly reliable shield property may be obtained, and a marking section having sufficient visibility may be formed.
Furthermore, if laser marking is performed after the sputtering the metal to form the shield layer, since metal generally has high laser reflectance, the laser output has to be increased, and the life of the laser components are reduced and frequent exchanges and repairs are required. However, since the marking is performed on the mold resin that satisfactorily absorbs laser light in the method described above, the laser output may be lower, and frequent exchanges and repairs are not required, and a decrease in the manufacturing cost and an increase of the workability may be obtained.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-258660 | Dec 2013 | JP | national |
