JPH053183A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To enable a semiconductor substrate to be enhanced in mechanical strength and lessened in thickness by a method wherein a protective film is provided to the semiconductor substrate to cover its surface including the side faces of bumps provided to pad electrodes, and the upside of the protective film is set level with those of the bumps so as to enable the upsides of the bumps to be exposed. CONSTITUTION:Pad electrodes 11 electrically connected to the outside are provided onto a semiconductor substrate 4 where semiconductor elements are formed, a metal film of Ti or the like is formed on the surface of the substrate 4 including the pad electrodes 11, the pad electrodes 11 are selectively plated with Au or the like making the metal film serve as a plating electrode, then the metal film is removed, and bumps 10 are formed. Then, a protective film 12 of epoxy resin or the like is applied onto all the surface of the substrate 4 including the bumps 10 as thick as 200mum and then cured. In succession, the semiconductor substrate 4 is rendered as thin as 200mum or so by grinding its rear side, and furthermore the protective film 12 is etched back to be as thin as 20mum or so to make the upsides of the bumps 10 exposed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and its manufacturing method.

[0002]

2. Description of the Related Art A conventional semiconductor device manufacturing method is as follows.
As shown in FIG. 3A, a pad electrode 11 for electrically connecting to the outside is selectively formed on the semiconductor substrate 4 on which the semiconductor element is formed.

Next, as shown in FIG. 3B, after depositing a metal film 14 of Ti, Cr, Cu or the like on the surface of the semiconductor substrate 4 including the pad electrode 11, the photolithography technique and the plating method are used. Bumps 10 of Au, Cu, Pb-Sn, etc. are selectively formed on the metal film 14 on the pad electrodes 11.
To form.

Next, as shown in FIG. 3C, the bump 1
The metal film 14 was removed by etching using 0 as a mask to form a semiconductor device.

Flip chip is one of the methods for mounting a semiconductor device having such bumps. This is Figure 4
As shown in (a), the bonding pad 13 of the mounting substrate 15 and the bump 10 made of Pb-Sn or the like are connected by melting by soldering. Then, a resin layer 17 such as an epoxy resin is coated to protect the semiconductor element.

Further, a semiconductor substrate 4 having bumps similarly.
There is a film carrier method as a method of mounting.
As shown in FIG. 4B, this is done by connecting the bump 10 and the inner lead 6 on the film carrier tape by thermocompression bonding or eutectic method (Inner Lead Bond).
ding). Next, for the purpose of improving reliability and mechanical protection, a resin layer 17 such as an epoxy resin is dropped on the surface of the semiconductor substrate 4 to seal the surface of the semiconductor chip with resin. Then, an electrical inspection and a burn-in test are performed using the electrical selection pad 9. Furthermore, when mounting on a mounting board, the outer lead 7 is cut into a predetermined size,
After molding, the bonding pad 13 of the mounting substrate 15 and the outer lead 7 are bonded and mounted.

[0007]

In the above-described semiconductor device, it is very difficult for the resin layer formed as a protection of the semiconductor element after flip-chip mounting to completely fill between the mounting substrate and the semiconductor substrate. It is difficult to confirm this. In the conventional semiconductor device, the semiconductor substrate has a thickness of 500 μm, and the resin layer has a thickness of 100 to 300 μm.
Therefore, it has a thickness of 600 to 800 μm as a whole. Along with the weight reduction and thickness reduction of electronic devices, further reduction in thickness of such semiconductor devices is required. That is,
It is necessary to further reduce the thickness of about 800 μm. Therefore, there is a method of grinding a semiconductor substrate, but it often results in damage such as cracking. Also, regarding the resin thickness, in order to completely cover the surface of the semiconductor element, it is necessary to drop a certain amount of resin, and there is a limit to thinning.

[0008]

The semiconductor device of the present invention comprises:
Protection by covering the pad electrode provided on the semiconductor substrate, the bump provided on the pad electrode, and the surface including the side surface of the bump and exposing the upper surface of the bump with the upper surface flush with the upper surface of the bump With a membrane.

A method of manufacturing a semiconductor device according to the present invention comprises a step of forming pad electrodes for external connection on a semiconductor substrate having a semiconductor element and selectively depositing a metal layer on the pad electrodes to form bumps. A step of forming a protective film on the surface including the bump, a step of grinding the back surface of the semiconductor substrate to reduce the thickness of the semiconductor substrate, and a step of grinding the protective film to expose an upper surface of the bump. And a process.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

1 (a) to 1 (c) are cross-sectional views of a semiconductor chip showing the order of steps for explaining a manufacturing method according to an embodiment of the present invention.

First, as shown in FIG. 1A, a pad electrode 11 for making an electrical connection to the outside is formed on a semiconductor substrate 4 on which a semiconductor element is formed by a process similar to the conventional example.
On the surface including the pad electrode 11, for example, Ti,
A metal film (not shown) of Cr, Cu or the like is formed, and then,
The bumps 10 are formed by selectively depositing Au, Cu, Pb-Sn or the like on the pad electrode 11 using the metal film as a plating electrode and then removing the metal film. In addition to the plating method, the bump is formed by ball-forming a wire made of Au, Pb-Sn, etc. by a wire bonding method, as described in JP-A-49-52973. After joining the ball on the pad, leaving only the ball,
A conventional bump forming method such as a method of forming a bump by cutting a wire or a method of immersing the wire in molten solder to form a solder bump only on a pad electrode can be used.

Next, as shown in FIG. 1B, the bump 10
A protective film 12 of, for example, Epokin resin is applied to a thickness of 200 μm on the entire surface of the semiconductor substrate 4 including, and is cured.

Next, as shown in FIG. 1C, the back surface of the semiconductor substrate 4 is ground to reduce the thickness of the semiconductor substrate to about 200 μm, and the protective film 12 is etched until the resin thickness reaches about 20 μm. Back up to expose the upper surface of the bump 10. In consideration of the heat dissipation of the semiconductor substrate 4, the height of the bumps 10 is increased in advance by forming the ball bumps in double or triple, and the resin thickness is about 100 μm in order to maintain the strength. The semiconductor substrate 4 to 50 μm
It may be thin to some extent.

2 (a) and 2 (b) are sectional views showing a mounted state of the semiconductor device of the present invention.

FIG. 2A shows an example of mounting by the flip chip method, in which the semiconductor device is mounted through the exposed bumps 10 or the second bumps 16 provided on the bonding pads 13 of the mounting substrate 15.

The bumps 16 can be formed by the plating method or the ball bump method as in the case of forming the bumps on the semiconductor substrate. In addition, the "Nikkei Microdevice", July, 1989 issue. , Pages 43 to 65, there is a method of further applying a conductive paste such as an Ag paste on the Au bump, a method of forming a conductive resin by printing or a dropping method, and the like. This can be easily performed by using the bump forming method. Also, minute pins or leads can be used instead of bumps. Next, a connection method, for example, when the combination of the exposed bump 10 and the second bump 16 is solder-solder, connection is performed by melting, and in the case of Au-Au, an anisotropic conductive sheet is used for connection. However, in the case of a conductive adhesive, an appropriate connection method is selected depending on the bump material such as connection by curing.

FIG. 2B shows a mounting example using a film carrier tape, in which the second bump 16 is formed on the bump 10 exposed on the protective film 12 or on the inner lead portion.
Inner lead bonding is performed by, for example, a thermocompression bonding method. Next, the bonding pad 1 on the mounting substrate 15
In 3, the outer lead portion 7 and the outer lead bonding are performed by, for example, a thermocompression bonding method. The method of forming the bumps 16 is the same as that of the flip chip. Further, it is also possible to directly bond the lead to the exposed bump 10 without forming the bump 16. Further, by directly wire-bonding on the exposed bump 10, it can be used as a semiconductor substrate for a conventional wire-bonding semiconductor device.

[0019]

As described above, according to the present invention, the thickness of the semiconductor substrate can be further reduced as compared with the conventional one, so that a thin and lightweight semiconductor device can be manufactured. Further, the protective resin can be formed easily and can be made thin. Further, when the entire surface of the mounting board is covered with resin after mounting by the conventional flip-chip method, it is difficult to replace individual units when a defect occurs after mounting on the board. Since it can be mounted, it also has an effect that individual units can be exchanged.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a semiconductor chip showing the order of steps for explaining a manufacturing method according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a mounted state of the semiconductor device of the invention.

FIG. 3 is a cross-sectional view of a semiconductor chip showing the order of steps for explaining a conventional method for manufacturing a semiconductor device.

FIG. 4 is a cross-sectional view showing a mounted state of a conventional semiconductor device.

[Explanation of symbols]

4 Semiconductor substrate 6 inner lead 7 Outer leads 10,16 bumps 11 Pad electrode 12 Protective film 13 Bonding pad 14 Metal film 15 Mounting board 17 Resin layer

Claims (3)

[Claims] 1. A pad electrode provided on a semiconductor substrate, a bump provided on the pad electrode, a surface including a side surface of the bump, and an upper surface of the bump that is flush with an upper surface of the bump. A semiconductor device having a protective film that exposes. 2. The semiconductor device according to claim 1, wherein the semiconductor substrate is thinner than the protective film. 3. A step of providing a pad electrode for external connection on a semiconductor substrate provided with a semiconductor element, selectively depositing a metal layer on the pad electrode to form a bump, and protecting a surface including the bump. A step of forming a film, a step of grinding the back surface of the semiconductor substrate to reduce the thickness of the semiconductor substrate, and a step of grinding the protective film to expose the upper surface of the bump. Of manufacturing a semiconductor device.