JP2004063515A - Method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent deteriorate connection reliability due to warp of a semiconductor element itself when a thin semiconductor element is connected with the flip-chip connection method. <P>SOLUTION: The method of manufacturing semiconductor device comprises the steps of forming a first semiconductor element to form a plurality of electrode pads 3 to the predetermined positions of a first semiconductor element wafer 1, forming a second semiconductor element to form a plurality of electrode pads 3 to the predetermined positions of a second semiconductor element wafer 2, dividing the first semiconductor element 1a into element pieces, dividing the second semiconductor element 2a into element pieces, forming a bump to the first semiconductor element 1a, connecting the first semiconductor element 2a with a flip-chip connection method, grinding the rear surface of the first semiconductor element 1a, bonding and mounting the second semiconductor element 2, connecting the second semiconductor element 2a with a wire bonding method, sealing the semiconductor element with resin, and dividing the semiconductor devices into device pieces. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a semiconductor device used for a semiconductor device bonded by a flip-chip method.
[0002]
[Prior art]
2. Description of the Related Art As portable information devices become smaller and lighter, higher density, smaller size and thinner semiconductor device packages are required. To meet these demands, a semiconductor device in which semiconductor elements are stacked and mounted in multiple stages has been developed. In such a device, it is necessary to grind the semiconductor element thinly in order to reduce the thickness.
[0003]
Conventionally, in order to reduce the thickness of chips, the back surface has been ground at the wafer stage. An example is shown below.
[0004]
6 and 7 are a flowchart of a manufacturing process showing a conventional method for manufacturing a semiconductor device and a process explanatory diagram corresponding to each process. Hereinafter, description will be made in accordance with the process order. First, in the first semiconductor element, a plurality of first semiconductor elements and their electrode pads 3 are formed at predetermined positions on the Si wafer 1 in a first semiconductor element forming step in FIG. In the backside grinding step of the wafer, the backside of the first semiconductor element wafer 1 is ground with a grinding wheel 4 to a predetermined thickness, for example, a wafer of t1 = 675 μm to t3 = 250 μm, and (c) in the first semiconductor element singulation step. The first semiconductor element wafer 1 is formed by attaching the first semiconductor element wafer 1 to a dicing tape 6 and cutting it with a dicing blade 5 to individually cut the first semiconductor elements 1a. Similarly, in the second semiconductor element, (d) a plurality of first semiconductor elements and their electrode pads 3 are formed at predetermined positions on the Si wafer in the second semiconductor element forming step, and (e) the second semiconductor element wafer is formed. In the back surface grinding step, the back surface of the second semiconductor element wafer 2 is ground with a grinding wheel 4 to a predetermined thickness, for example, a wafer with t1 = 675 μm to t3 = 250 μm, and (f) in the second semiconductor element singulation step, The second semiconductor element wafer 2 is attached to a dicing tape 6 and cut by a dicing blade 5, and the second semiconductor elements are individually cut into individual pieces.
[0005]
Next, an Au ball bump 7 having a height of 50 μm is formed on the electrode pad 3 in a first semiconductor element bump forming step in FIG. Next, (b) in the first semiconductor element flip chip process, the conductive adhesive is transferred only to the Au ball bumps 7 formed on the electrode pads 3 of the plurality of first semiconductor elements 1a by the transfer method, and the wiring substrate 8 is formed. The first connection terminal 9 is positioned and mounted. Thereafter, the conductive adhesive is thermally cured, and the first sealing resin 10 is injected into a gap between the first semiconductor element 1a and the wiring board 8 having a thickness of 300 μm. Thereafter, the first sealing resin 10 is thermally cured to complete the flip chip connection. Next, in the second semiconductor element bonding and mounting step (c), the same number of second semiconductor elements 2a are bonded and mounted on the plurality of first semiconductor elements 1a. Next, in the second semiconductor element wire bonding step (d), the electrode pads 3 of the second semiconductor element 2a and the second connection terminals 11 are connected by bonding wires 12. Next, in the semiconductor element resin sealing step (e), the first and second semiconductor elements that have been connected are covered with the second sealing resin 13 for the purpose of protection. At this time, in order to cover the bonding wires, a thickness of the second sealing resin of 250 μm is required on the second semiconductor element 2a. Next, in the semiconductor device singulation step (f), a plurality of semiconductor devices are divided. Through the steps of FIGS. 6 and 7, the semiconductor device manufacturing process is completed. Through the above steps, a stacked semiconductor element device having a thickness of 1.1 mm is completed.
[0006]
[Problems to be solved by the invention]
As described above in the prior art, the semiconductor element stacked semiconductor device has the following problems.
[0007]
FIG. 8 is a structural cross-sectional view of a semiconductor element stacked type semiconductor device. The second semiconductor element 2a is bonded and mounted on the upper surface of the first semiconductor element 1a which is flip-chip connected on the wiring board 8 and connected by the bonding wire 12, and the semiconductor elements 1a and 1b are connected by the second sealing resin 13. In order to reduce the thickness of the present semiconductor device, it is necessary to reduce the thickness of a semiconductor element in the semiconductor device.
[0008]
When an underfill resin is used for flip chip bonding, a stress is generated on the surface of the semiconductor element due to curing of the resin after the underfill is injected. If the semiconductor element has a sufficient thickness, the semiconductor element can withstand stress as a rigid body. However, in the case of a thin chip, the stress generated at the time of curing becomes a problem. This will be described below with reference to the drawings.
FIG. 9 is a cross-sectional view showing a structure of a connection portion in a flip chip process of a conventional semiconductor device. In order to reduce the thickness, the first semiconductor element 1a is ground after the back surface is ground at the wafer stage. The first semiconductor element is mounted on the wiring substrate 8 by flip-chip connection, but the first semiconductor element 1a is distorted and warped, so that the connection state between the end portion and the central portion is different, and the connection at the central portion is different. There is a problem that reliability is reduced.
[0009]
Further, the thinned semiconductor element is difficult to handle and has a high risk of being broken in a flip chip process.
[0010]
Accordingly, an object of the present invention is to provide a method of manufacturing a semiconductor device that can be thinned to a desired thickness without deteriorating the connection reliability of flip-chip connection of a first semiconductor element.
[0011]
[Means for Solving the Problems]
An object of the present invention is to provide a semiconductor device which can cope with the above-mentioned conventional problems and future trends of the semiconductor device.
[0012]
The method of manufacturing a semiconductor device according to claim 1 includes a first step of flip-chip mounting a semiconductor element on a wiring board and a second step of thinning the flip-chip mounted semiconductor element.
[0013]
According to the method of manufacturing a semiconductor device according to the first aspect, after the flip chip is formed, the connection reliability of the semiconductor element can be improved by reducing the thickness of the semiconductor element, and the semiconductor in the flip chip process can be realized. It is possible to prevent the element from being damaged. Therefore, a thin semiconductor device having excellent connection reliability can be realized.
[0014]
3. The method of manufacturing a semiconductor device according to claim 2, wherein the first step of flip-chip mounting a plurality of semiconductor elements on a wiring board on which a plurality of flip-chip wirings for a semiconductor device are patterned; And a second step of collectively thinning the elements.
[0015]
According to the method of manufacturing a semiconductor device of the second aspect, in addition to the same effects as those of the first aspect, the efficiency of manufacturing the semiconductor device can be increased.
[0016]
A method of manufacturing a semiconductor device according to claim 3, wherein a first step of flip-chip mounting the first semiconductor element on the wiring board, and a second step of thinning the first semiconductor element mounted on the flip chip. A third step of mounting the second semiconductor element on the back surface of the thinned first semiconductor element.
[0017]
According to the method of manufacturing a semiconductor device according to the third aspect, the same effect as that of the first aspect is obtained in the method of manufacturing a semiconductor element stacked semiconductor device.
[0018]
According to a fourth aspect of the present invention, in the semiconductor device manufacturing method according to the first aspect, the second step of thinning the semiconductor device is performed by grinding.
[0019]
According to the method of manufacturing a semiconductor device of the fourth aspect, the same effect as that of the first aspect is obtained.
[0020]
According to a fifth aspect of the present invention, there is provided a method of manufacturing a semiconductor device according to the first, second, third, or fourth aspect, wherein the method of flip-chip mounting a semiconductor element on a wiring board includes forming bumps on electrode pads of the semiconductor element. Forming, transferring a conductive adhesive only to the bumps formed on the electrode pads of the semiconductor element by a transfer method, and joining the electrode pads of the semiconductor element and the connection terminals of the wiring board via the conductive adhesive Then, a step of thermally curing the conductive adhesive and a step of injecting a sealing resin into a gap between the semiconductor element and the wiring board and thermally curing the resin to perform resin sealing.
[0021]
According to the method of manufacturing a semiconductor device according to the fifth aspect, the same effects as those of the first, second, third, or fourth aspects are obtained.
[0022]
According to a sixth aspect of the present invention, in the method for manufacturing a semiconductor device according to any one of the first, second, third, fourth, and fifth aspects, the step of collectively thinning the back surface of the semiconductor element includes the step of reducing the thickness of the semiconductor element. Is ground to 50 to 250 μm.
[0023]
According to the method of manufacturing a semiconductor device according to the sixth aspect, the same effects as those of the first, second, third, fourth, or fifth aspects are obtained.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
A first embodiment of the present invention will be described with reference to FIGS.
[0025]
FIG. 1 is a flowchart illustrating a method for manufacturing a semiconductor device according to the first embodiment. Hereinafter, description will be made in accordance with the process order. In the first semiconductor element, (a) a plurality of first semiconductor elements and their electrode pads 3 are formed at predetermined positions on the Si wafer 1 in a first semiconductor element forming step; In the forming step, the first semiconductor element wafer 1 is attached to a dicing tape 6 and cut by a dicing blade 5, and the first semiconductor elements 1a are individually cut. The thickness of the semiconductor element 1a up to this step is desirably 250 μm or more in consideration of handling and the like. Next, in a (c) first semiconductor element bump formation step, an Au ball bump 7 having a height of about 15 to 50 μm is formed on the electrode pad 3 of the semiconductor element 1a. For example, the Au ball bump 7 is formed by using a wire bonding method. In this method, a ball formed at the tip of an Au wire is thermocompression-bonded with an ultrasonic wave to the electrode pad 3 of the semiconductor element 1a to form a lower portion of the Au ball, and further, the capillary is moved to cut the Au wire. However, it is not necessary to adopt this method for forming the Au ball, and a plating method, a printing method, or the like may be used.
[0026]
Next, in FIG. 2A, in a first semiconductor element flip chip process, a conductive adhesive is transferred only to the Au ball bumps 7 formed on the electrode pads 3 of the plurality of first semiconductor elements 1a by a transfer method. The semiconductor device wiring is patterned and mounted on the first connection terminal 9 of the 300 μm-thick wiring substrate 8 on which the wiring for the semiconductor device is patterned. Thereafter, the conductive adhesive is thermally cured, and the first sealing resin 10 is injected into the gap between the first semiconductor element 1a and the wiring board 8. Thereafter, the first sealing resin 10 is thermally cured to complete the flip chip connection. The conductive adhesive may be a resin-based material such as an Au paste or an Ag paste, or a metal-based material such as an In-based solder. Next, in the first semiconductor element back surface grinding step (b), the back surface of the connected first semiconductor element 1a is ground with a grinding wheel 4 to a predetermined thickness, for example, t3 = less than 150 μm. Next, in the (c) semiconductor device singulation step, a plurality of semiconductor devices are divided. Through the steps (a) to (c) of FIGS. 1 and 2 described above, the semiconductor device manufacturing process is completed. It is desirable that the thickness of the first semiconductor element 1a before the first semiconductor element flip chip process of FIG. 2A be 250 μm or more.
[0027]
As shown in FIG. 3, when the thinned semiconductor element 1a is flip-chip bonded, when the semiconductor element 1a having a thickness of 250 μm or more is flip-chip bonded, no warping due to resin stress is observed. And the warpage of the semiconductor element 1a increases. However, when the 250 μm semiconductor element 1a was flip-chip bonded and then ground, no change in warpage was observed, indicating the effect of the present invention.
[0028]
Further, in the present embodiment, after a plurality of semiconductor elements 1a are flip-chip bonded on a wiring substrate on which a plurality of wirings for semiconductor devices are patterned, grinding is performed, and then the semiconductor elements 1a are divided into individual semiconductor devices. The semiconductor element 1a may be flip-chip bonded to the wiring substrate 8 divided into individual semiconductor devices, and a flow of grinding may be performed. Through the above steps, a semiconductor device having a thickness of 0.5 mm or less is completed.
[0029]
A second embodiment of the present invention will be described with reference to FIGS.
[0030]
FIG. 4 is a flowchart illustrating a method for manufacturing a semiconductor device according to the second embodiment. Hereinafter, description will be made in accordance with the process order. In the first semiconductor element, (a) a plurality of first semiconductor elements and their electrode pads 3 are formed at predetermined positions on the Si wafer 1 in a first semiconductor element forming step; In the forming process, the first semiconductor element wafer 1 is attached to a dicing tape 6 and cut by a dicing blade 5 to form the first semiconductor elements 1a individually. The thickness of the first semiconductor element 1a up to this step is desirably 250 μm or more in consideration of handling and the like. Next, in the second semiconductor element, (c) a plurality of second semiconductor elements and their electrode pads 3 are formed at predetermined positions on the Si wafer 2 in the second semiconductor element forming step, and (d) the second semiconductor element is formed. In the element singulation step, the second semiconductor element wafer 2 is attached to a dicing tape 6 and cut by a dicing blade 5 to form the second semiconductor elements individually. The thickness of the second semiconductor element 2a up to this step is desirably 250 μm or more in consideration of handling and the like.
[0031]
Next, (e) Au ball bumps 7 having a height of about 15 to 50 μm are formed on the electrode pads 3 in a first semiconductor element bump formation step. For example, the Au ball bump 7 is formed using a wire bonding method. In this method, the ball formed at the tip of the Au wire is thermocompression-bonded with the ultrasonic wave to the electrode pad 3 of the semiconductor element 1a, thereby forming the lower portion of the Au ball and further moving the capillary to cut and form the Au wire. However, it is not necessary to adopt this method for forming the Au ball, and a plating method, a printing method, or the like may be used. Next, in the first semiconductor element flip chip process, (f) the plurality of first semiconductor elements 1a are formed. A conductive adhesive is transferred only to the Au ball bumps 7 formed on the electrode pads 3 by a transfer method, and is positioned and mounted on the first connection terminals 9 of the wiring board 8. Thereafter, the conductive adhesive is thermally cured, and the first sealing resin 10 is injected into a gap between the first semiconductor element 1a and the wiring board 8 having a thickness of 300 μm. Thereafter, the first sealing resin 10 is thermally cured to complete the flip chip connection. The conductive adhesive may be a resin-based material such as an Au paste or an Ag paste, or a metal-based material such as an In-based solder.
[0032]
Next, FIG. 5A shows the first semiconductor element back surface grinding step, in which the back surface of the connected first semiconductor element 1a is ground with a grinding wheel 4 to a predetermined thickness, for example, t3 = less than 100 μm (grinding). ). Next, (b) shows a bonding and mounting step of the second semiconductor element 2a, in which the same number of second semiconductor elements 2a are bonded and mounted on the plurality of first semiconductor elements 1a. 2C, in a second semiconductor element wire bonding step, the electrode pads 3 of the second semiconductor element 2a and the second connection terminals 11 are connected by bonding wires 12. (D) is a semiconductor element resin encapsulation step, in which the second encapsulation resin 13 is raised to a height of 250 μm above the second semiconductor element 2a for the purpose of protecting the connected first and second semiconductor elements 1a and 2a. Cover with. Next, in the semiconductor device singulation step (e), a plurality of semiconductor devices are divided. Through the steps shown in FIGS. 4 and 5, the manufacturing process of the semiconductor device is completed. As in the first embodiment, the thickness of the first semiconductor element 1a up to the first semiconductor element flip chip process in FIG. 4F is desirably 250 μm or more.
[0033]
Further, in the present embodiment, a wiring substrate in which wiring for a plurality of semiconductor devices is patterned is used, and finally, the wiring substrate is divided into individual semiconductor devices. However, the wiring substrate divided into individual semiconductor devices is used from the beginning. You may take a flow. Through the above steps, a thin stacked semiconductor device of less than 0.95 mm and 1 mm is completed.
[0034]
As described above, the first semiconductor element is used in the first semiconductor element flip-chip process by using a thickness that is small in distortion and less warped and easy to handle as a wafer (handling) until the flip-chip process. Stable connection is possible, and connection reliability can be improved. Further, in the first semiconductor element back surface grinding step, the back surface of the first semiconductor element to which connection has been completed can be ground to an arbitrary thickness, and the thickness of the semiconductor device can be reduced. Therefore, for example, the problem of the invention described with reference to FIGS. 8 and 9 can be solved.
[0035]
In each of the above embodiments, the semiconductor elements are collectively thinned, but may be individually thinned.
[0036]
If the thickness of the semiconductor element is less than 300 μm, a stable chip shape cannot be obtained due to warpage of the semiconductor chip.
[0037]
In the step of thinning the back surface of the semiconductor element, the thickness of the semiconductor element is preferably ground to 50 to 250 μm or less than 250 μm.
[0038]
【The invention's effect】
According to the method of manufacturing a semiconductor device according to the first aspect, after the flip chip is formed, the connection reliability of the semiconductor element can be improved by reducing the thickness of the semiconductor element, and the semiconductor in the flip chip process can be realized. It is possible to prevent the element from being damaged. Therefore, a thin semiconductor device having excellent connection reliability can be realized.
[0039]
According to the method of manufacturing a semiconductor device of the second aspect, in addition to the same effects as those of the first aspect, the efficiency of manufacturing the semiconductor device can be increased.
[0040]
According to the method of manufacturing a semiconductor device according to the third aspect, the same effect as that of the first aspect is obtained in the method of manufacturing a semiconductor element stacked semiconductor device.
[0041]
According to the method of manufacturing a semiconductor device of the fourth aspect, the same effect as that of the first aspect is obtained.
[0042]
According to the method of manufacturing a semiconductor device according to the fifth aspect, the same effects as those of the first, second, third, or fourth aspects are obtained.
[0043]
According to the method of manufacturing a semiconductor device according to the sixth aspect, the same effects as those of the first, second, third, fourth, or fifth aspects are obtained.
[Brief description of the drawings]
FIGS. 1A and 1B are a flowchart of a manufacturing process showing a method of manufacturing a semiconductor device according to a first embodiment of the present invention, and a process explanatory diagram for each process.
FIG. 2 is a flowchart following FIG. 1 and a process explanatory diagram for each process.
FIG. 3 shows the relationship between the grinding step and the warpage, wherein the horizontal axis represents the thickness of the semiconductor element and the vertical axis represents the relation between the warpage (μm) of the semiconductor element.
FIGS. 4A and 4B are a flowchart of a manufacturing process showing a method of manufacturing a semiconductor device according to a second embodiment of the present invention and a process explanatory diagram for each process.
FIG. 5 is a flowchart following FIG. 4 and a process explanatory diagram for each process.
FIG. 6 is a flowchart of a manufacturing process showing a conventional method for manufacturing a semiconductor device and a process explanatory diagram for each process.
FIG. 7 is a flowchart following FIG. 6 and a process explanatory diagram for each process.
FIG. 8 is a structural sectional view of a semiconductor element stacked type semiconductor device.
FIG. 9 is an enlarged cross-sectional view showing a structure of a connection part in a flip chip process of a conventional semiconductor device.
[Explanation of symbols]
Reference Signs List 1 first semiconductor element wafer 1a first semiconductor element 2 second semiconductor element wafer 2a second semiconductor element 3 electrode pad 4 grinding wheel 5 dicing blade 6 dicing tape 7 Au ball bump 8 wiring board 9 first connection terminal 10 first seal Stop resin 11 Second connection terminal 12 Bonding wire 13 Second sealing resin

Claims (6)

A method of manufacturing a semiconductor device, comprising: a first step of flip-chip mounting a semiconductor element on a wiring substrate; and a second step of thinning the flip-chip mounted semiconductor element. A semiconductor comprising: a first step of flip-chip mounting a plurality of semiconductor elements on a wiring substrate on which wiring for a plurality of semiconductor devices is patterned; and a second step of collectively thinning the flip-chip mounted semiconductor elements. Device manufacturing method. A first step of flip-chip mounting a first semiconductor element on a wiring board, a second step of thinning the first semiconductor element flip-chip mounted, and the thinned first semiconductor element And mounting a second semiconductor element on the back surface of the semiconductor device. 2. The method of manufacturing a semiconductor device according to claim 1, wherein in the second step of thinning the semiconductor device, the thinning is performed by grinding. A method of flip-chip mounting a semiconductor element on a wiring board includes a step of forming a bump on an electrode pad of the semiconductor element and a step of transferring a conductive adhesive to only the bump formed on the electrode pad of the semiconductor element by a transfer method. Bonding the electrode pads of the semiconductor element and the connection terminals of the wiring board via the conductive adhesive, and thermally curing the conductive adhesive; and forming the semiconductor element and the wiring board. 5. The method for manufacturing a semiconductor device according to claim 1, further comprising a step of injecting a sealing resin into a gap between the semiconductor device and the resin and thermally curing the resin to perform resin sealing. 6. The semiconductor according to claim 1, wherein the step of batch-thinning the back surface of the semiconductor element includes grinding the thickness of the semiconductor element to 50 to 250 [mu] m. Device manufacturing method.

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