JP3826811B2 - Manufacturing method of semiconductor device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a semiconductor device in which a reinforcing member is bonded to the back surface of an electrode forming surface of a semiconductor element with an adhesive.
[0002]
[Prior art]
A semiconductor device mounted on a substrate of an electronic device is manufactured through a packaging process in which a lead frame pin or a metal bump is connected to a semiconductor element on which a circuit pattern is formed in a wafer state and sealed with a resin or the like. Has been. Along with the recent miniaturization of electronic devices, the miniaturization of semiconductor devices is also progressing, and in particular, efforts to make semiconductor elements thinner are being actively carried out.
[0003]
Since a thinned semiconductor element is weak against external force and easily damaged during handling, a semiconductor device using a semiconductor element thinner than the conventional one is reinforced by attaching a reinforcing member to the semiconductor element. The The reinforcement member is attached by pressure-bonding the reinforcement member to the opposite side of the bump formation surface of the semiconductor element using an adhesive.
[0004]
[Problems to be solved by the invention]
However, in the above-described crimping step of the reinforcing member, the flatness of the semiconductor element or the semiconductor is caused by air remaining between the surface opposite to the bump forming surface of the semiconductor element and the bonding interface of the adhesive. Problems are likely to occur when mounting the device. That is, when the semiconductor element is attached to the reinforcing member, air is easily caught in the bonding interface, and the entrained air partially forms a void.
[0005]
In the crimping process in which the reinforcing member is pressed and joined to the semiconductor element, the semiconductor wafer in the part where the void exists is partially deformed by the air pressure in the void. This is not the same plane as this part, resulting in poor flatness. Further, when the semiconductor device is mounted on the substrate and sent to the reflow with air contained in the bonding interface in this way, there is a case where a gas in the void expands due to heating and causes a rupture.
[0006]
Accordingly, the present invention provides a method for manufacturing a semiconductor device in which voids are not formed at the bonding interface in the crimping process for bonding reinforcing members, and defects in flatness and mounting defects caused by the voids can be prevented. For the purpose.
[0007]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a method for manufacturing a semiconductor device, comprising: bonding a reinforcing member via a resin adhesive material that expands and contracts on a back surface of a bump forming surface in which a bump is formed on an electrode for external connection of a semiconductor element. A semiconductor device manufacturing method for manufacturing a semiconductor device, wherein a semiconductor wafer having a bump formed on the electrodes of a plurality of semiconductor elements is separated for each semiconductor element, and the semiconductor is separated after the semiconductor element separation process. look including a reinforcing member bonding step of pressure bonding the reinforcing member through the material of the resin adhesive to stretch the back surface of the element, in the semiconductor device isolation process, a semiconductor wafer in a state in which the seat on the bump formation surface is adhered After polishing and thinning, the semiconductor wafer is cut to separate each semiconductor element .
[0010]
According to the present invention, a semiconductor wafer having bumps formed on electrodes of a plurality of semiconductor elements is separated for each semiconductor element, and then a reinforcing member is crimped to the back surface of the semiconductor element via a resin adhesive. In the process, voids are not formed at the bonding interface, and defects in flatness and defects after mounting due to the voids can be prevented.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings. 1, 2, 3, and 5 are process explanatory views of a method for manufacturing a semiconductor device according to an embodiment of the present invention. FIG. 4 is an explanatory view of a process of a semiconductor device mounting method according to an embodiment of the present invention. It is.
[0012]
First, a method of manufacturing a semiconductor device will be described with reference to FIGS. This semiconductor device manufacturing method manufactures a semiconductor device in which a reinforcing member is joined to a back surface of a bump forming surface on which bumps are formed on an external connection electrode of a semiconductor element via a low elastic modulus resin adhesive. To do.
[0013]
In FIG. 1A, reference numeral 1 denotes a semiconductor wafer on which a plurality of semiconductor elements are formed. Bumps 2 are formed on external connection electrodes (not shown) on the upper surface of the semiconductor wafer 1. As shown in FIG. 1B, a dicing sheet 3 is adhered to the surface opposite to the bump forming surface of the semiconductor wafer 1. Then, dicing of the semiconductor wafer 1 is performed with the dicing sheet 3 adhered, and a cutting groove 1b for partially cutting the thickness of the semiconductor wafer 1 is formed at the boundary of each semiconductor element 1a.
[0014]
Next, in this state, the semiconductor wafer 1 is inverted together with the dicing sheet 3 so that the bump forming surface is in a downward posture. And the protection sheet 4 for reinforcement in the thinning process is stuck on the bump forming surface of each semiconductor element 1a of the semiconductor wafer 1 as shown in FIG. Here, an adhesive resin layer 4a is formed on the surface of the protective sheet 4. By pressing the bump forming surface of each semiconductor element 1a against the adhesive resin layer 4a, bumps are formed as shown in FIG. 2 is embedded in the adhesive resin layer 4a, and the surface of the semiconductor element 1a is in close contact with the surface of the adhesive resin layer 4a. Thereafter, the dicing sheet 3 is peeled from the semiconductor wafer 1 as shown in FIG.
[0015]
Next, the semiconductor wafer 1 from which the dicing sheet 3 has been peeled is sent to a polishing process. As shown in FIG. 2A, the opposite side of the bump forming surface of the semiconductor wafer 1 is mechanically polished by the polishing tool 5. As a result, the remaining uncut thickness in the dicing process is removed from the opposite side of the bump forming surface, and the semiconductor wafer 1 is thinned to a thickness of about 50 μm and separated into each semiconductor element 1a (semiconductor element separation). Process).
[0016]
Next, the stress layer is removed by plasma etching. Here, as shown in FIG. 2B, the semiconductor wafer 1 reinforced by the protective sheet 4 and mechanically polished is placed on a placement portion 8 provided in a treatment chamber 7 of the plasma treatment apparatus 6. . Then, by generating plasma in the processing chamber 7, the stress layer including microcracks generated on the polished surface in the mechanical polishing in the previous process is removed by plasma etching. Thereby, the strength of the thinned semiconductor wafer 1 is improved. In addition to the plasma etching, the stress layer may be removed by a polishing method or chemical etching using a chemical solution. Further, the step of removing the stress layer may be omitted.
[0017]
Thereafter, as shown in FIG. 2C, the reinforcing member 11 is bonded to the opposite surface (back surface) of the bump forming surface of the semiconductor element 1 a separated and thinned through the adhesive 10. The reinforcing member 11 is a reinforcing member in which a material such as resin, ceramic, or metal is formed in a plate shape. The adhesive 10 is a resin adhesive having a low elastic modulus, and a material such as an elastomer that has a small elastic coefficient in a joined state and can easily expand and contract with a small external force is used.
[0018]
The reinforcing member 11 functions as a holding unit for handling the semiconductor device in a state in which the semiconductor device is formed by being cut for each semiconductor element 1a, and as a reinforcing member that protects the semiconductor element 1a from external force and impact. It also has a role. For this reason, the reinforcing member 11 has a sufficient thickness having a bending rigidity larger than that of the semiconductor element 1a.
[0019]
After reinforcement member joining, as shown in FIG.2 (d), the protection sheet 4 is peeled from the bump formation surface of each semiconductor element 1a. Next, the semiconductor element 1a bonded to the reinforcing member 11 is sent to the reinforcing member crimping step. As shown in FIG. 3 (a), the reinforcing member 11 to which the individual semiconductor elements 1a are bonded is held by the pressure-bonding head 12, and the bump forming surface is brought into contact with the pressing surface of the thermocompression-bonding stage 13 to which the heat-resistant sheet 14 is attached. Press against it with a predetermined load. As a result, the reinforcing member 11 is bonded to the back surface of the semiconductor element 1 a via the adhesive material 10.
[0020]
In this reinforcing member crimping step, air is likely to be caught in the bonding interface between the back surface of the semiconductor element 1a and the adhesive 10, and the remaining air is likely to form the void 10a as shown in FIG. Even in such a case, since the cut groove 1b is formed in advance between the semiconductor elements 1a by dicing, the void 10a remaining at the bonding interface in the process of thermocompression bonding passes through the cut groove 1b. Most of the voids are discharged, and there are very few voids remaining at the joint interface after completion of thermocompression bonding. Therefore, after the pressing state by the crimping head 12 is released, the occurrence of a flatness defect caused by the presence of voids is extremely small.
[0021]
Next, the semiconductor element 1a after the thermocompression bonding is sent to the individual piece separation step and divided into individual semiconductor devices. Here, as shown in FIG. 3D, the reinforcing member 11 is cut for each semiconductor element 1a and separated into individual reinforcing members 11a. At this time, the reinforcing member 11 is separated with a dicing width b2 that is narrower than the dicing width b1 of the semiconductor element 1a in the dicing step shown in FIG.
[0022]
Thereby, the individual semiconductor device 15 is completed. The semiconductor device 15 includes a semiconductor element 1a on which external connection bumps 2 are formed, and a reinforcing member 11a bonded to the opposite surface of the bump formation surface of the semiconductor element 1a with an adhesive material 10. ing. The size B2 of the reinforcing member 11a is larger than the size B1 of the semiconductor element 1a, and the outer peripheral end protrudes outward from the outer peripheral end of the semiconductor element 1a, so that the semiconductor element 1a is also handled when the semiconductor device 15 is handled from the side. The shape is such that is protected.
[0023]
In the manufacturing process of the semiconductor device 15, damage occurs when bumps are formed while the semiconductor wafer 1 is constrained by the resin layer by bonding the reinforcing member 11 with the bumps 2 formed on the semiconductor wafer 1. Can be prevented, and the processing yield can be improved.
[0024]
The mounting of the semiconductor device 15 will be described with reference to FIG. As shown in FIG. 4A, the semiconductor device 15 is held by adsorbing and holding the upper surface of the reinforcing member 11 a by the mounting head 16, and is moved above the substrate 17 by moving the mounting head 16. Then, the mounting head 16 is lowered with the bumps 2 of the semiconductor device 15 aligned with the electrodes 17a of the substrate 17, and the bumps 2 of the semiconductor element 1a are landed on the electrodes 17a as shown in FIG. 4B.
[0025]
Thereafter, by heating the substrate 17, the bumps 2 are soldered to the electrodes 17a. In other words, the reinforcing member 11 a is held by the mounting head 16 in handling when the semiconductor device 15 is mounted on the substrate 17. The bonding of the bump 2 to the electrode 17a is performed by a method of bonding the semiconductor device 15 and the substrate 17 with a resin in a state where the bump 2 and the electrode 17a are press-contacted in addition to solder bonding, or by metal-to-metal bonding between the bump 2 and the electrode 17a. Alternatively, a bonding method using a conductive resin adhesive may be used. In this mounting process, since there is very little void remaining at the bonding interface between the adhesive 10 and the semiconductor element 1a, there is almost no problem that the gas in the void expands due to heating and ruptures.
[0026]
The mounting structure formed by mounting the semiconductor device 15 on the substrate 17 is configured such that the semiconductor device 15 is fixed to the substrate 17 by bonding the bumps 2, which are electrodes of the semiconductor device 15, to the electrodes 17 a of the substrate 17. Yes. As shown in FIG. 4 (c), when the substrate 17 is bent and deformed by some external force after mounting, the semiconductor element 1a is thin and easily bent, and the adhesive 10 is a material that is easily deformed with a low elastic coefficient. Therefore, only the adhesive layer of the semiconductor element 1a and the adhesive 10 is deformed following the bending deformation of the substrate 17.
[0027]
As a result, the stress at the joint portion is relieved without requiring a reinforcement treatment such as filling with an underfill resin after mounting, and the semiconductor element 1a and the reinforcing member 11a are simply joined by the adhesive 10 in a simple form. The package structure ensures reliability after mounting.
[0028]
In the above embodiment, in the semiconductor element separation step, the semiconductor wafer 1 is separated into individual semiconductor elements 1a by partially cutting the thickness of the semiconductor wafer 1 and then polishing and removing the remaining thickness after cutting. However, a method as illustrated in FIG. 5 may be used. That is, as shown to Fig.5 (a), the bump formation surface of the semiconductor wafer 1 is affixed on the protection sheet 4 in which the adhesion resin layer 4a was formed in the surface. In this state, the semiconductor wafer 1 is thinned by mechanically polishing the surface opposite to the bump forming surface with the polishing tool 5. Thereafter, stress is removed from the polished semiconductor wafer 1 in the same manner as the method shown in FIG. Note that the removal of the stress layer may be omitted as in the above-described embodiment.
[0029]
The surface opposite to the bump forming surface of the semiconductor wafer 1 after thinning is attached to the dicing sheet 3 as shown in FIG. 5C, and then the protective sheet 4 is peeled off from the bump forming surface. Thereafter, the semiconductor wafer 1 is sent to a dicing process, where a cutting groove 1b ′ for completely cutting the remaining thickness in the polishing is formed. As a result, the semiconductor wafer 1 is separated into individual semiconductor elements 1a.
[0030]
Thereafter, the semiconductor element 1a is peeled off from the dicing sheet and attached to the adhesive 10 of the reinforcing member 11, and the semiconductor device 15 is obtained in the same procedure as the steps shown in FIGS. 3 (a) to 3 (d).
[0031]
【The invention's effect】
According to the present invention, after the semiconductor wafer having the bumps formed on the electrodes of the plurality of semiconductor elements is separated for each semiconductor element, the reinforcing member is pressure-bonded to the back surface of the semiconductor element via the resin adhesive. In the crimping process, voids are not formed at the bonding interface, and it is possible to prevent defects in flatness and defects after mounting due to the voids.
[Brief description of the drawings]
FIG. 1 is a process explanatory diagram of a semiconductor device manufacturing method according to an embodiment of the present invention. FIG. 2 is a process explanatory diagram of a semiconductor device manufacturing method according to an embodiment of the present invention. FIG. 4 is a process explanatory diagram of a semiconductor device mounting method according to an embodiment of the present invention. FIG. 5 is a process explanatory diagram of a semiconductor device manufacturing method according to an embodiment of the present invention. Process description of the method 【Explanation of symbols】
DESCRIPTION OF SYMBOLS 1 Semiconductor wafer 1a Semiconductor element 1b Cutting groove 2 Bump 4 Protection sheet 4a Adhesive resin layer 10 Adhesive material 11 and 11a Reinforcing member 15 Semiconductor device

Claims (1)

A semiconductor device manufacturing method for manufacturing a semiconductor device in which a reinforcing member is bonded to a back surface of a bump forming surface on which bumps are formed on an electrode for external connection of a semiconductor element via a resin adhesive material that expands and contracts. A semiconductor element separation step for separating a semiconductor wafer having bumps formed on the electrodes of a plurality of semiconductor elements for each semiconductor element, and a resin adhesive made of a material that expands and contracts on the back surface of the semiconductor element after the semiconductor element separation step. A reinforcing member crimping step for crimping a reinforcing member through the semiconductor element , and in the semiconductor element separation step, the semiconductor wafer is polished and thinned in a state where a sheet is adhered to the bump forming surface, and then the semiconductor wafer is cut method of manufacturing a semi-conductor device you and separating each semiconductor element by.

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