JPH04323838A - Method of mounting semiconductor element - Google Patents

Abstract

PURPOSE:To prevent generation of faulty connection due to spreading of adhesive at the time of junction while reducing a pad pitch when a semiconductor element is mounted on a circuit board. CONSTITUTION:In case of mounting a semiconductor element on a circuit board by a wireless bonding method, a process of putting a spacer 24 into adhesive 25, a process of applying the adhesive 25 to the surface of a bump 22 of the semiconductor element 21 and a process of mounting the semiconductor element 21 on the circuit board 26 while connecting to an electrode 27 of the circuit board 26 through the adhesive 25 are performed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of mounting a semiconductor element (IC chip) on a circuit board using a wireless bonding method.

0002

[Prior Art] Conventionally, technologies in this field include:
For example, there was one described in JP-A-62-244142. FIG. 3 is a cross-sectional view of a conventional process for forming Au bumps on a semiconductor device. First, as shown in FIG. 3A, electrode pads 2 made of, for example, Al and a passivation film 3 are formed on a semiconductor element 1.

Next, as shown in FIG. 3(b), Ti--Pt, Au, etc. are sequentially laminated thereon by, for example, vacuum evaporation to form a diffusion control layer 4 and a bump bonding layer 5. . Next, as shown in FIG. 3(c), a liquid photoresist 6 is applied using a spinner or the like, and a bump diameter of a desired size is patterned only on the upper part of the electrode pad 2 in the wiring of the semiconductor element 1. Open a hole.

Next, as shown in FIG. 3(d), using this photoresist 6 as a plating mask, holes are opened in the diffusion control layer 4 and the bump bonding layer 5 as one cathode for electrolytic plating, and the exposed upper part of the pad is opened. The bumps 7 (here, Au) are selectively deposited only on the bump bonding layer 5. After that, Fig. 3(e)
), the photoresist 6 is removed and the bump 7 is removed.
Using this as a mask, the diffusion control layer 4 and bump bonding layer 5 other than the upper part of the pad are removed by etching. Note that, if necessary, heat treatment is performed for the purpose of reducing the contact resistance of the diffusion control layer 4.

The process of mounting a semiconductor element having bumps formed in this way onto a circuit board will be described with reference to FIG. First, as shown in FIG. 4(a), a semiconductor element 8 having bumps 7 is prepared. Next, Figure 4(b)
As shown in FIG. 2, a conductive adhesive resin such as Ag paste 9 is applied onto the bumps 7.

Next, as shown in FIG. 4(c), the bumps 7 are aligned so that they are above the circuit board electrodes 11 on the circuit board 10, and a little heat is applied while applying pressure.
The Ag paste 9 is cured. In this way, the bumps 7 and the circuit board electrodes 11 are connected via the Ag paste 9, and the semiconductor element mounting process is completed.

[0007]

[Problems to be Solved by the Invention] However, as described above, since the top surface of the bump is made into a hemispherical shape by the Ag paste 9, when bonding the bump 7 and the circuit board electrode 11,
Variations in the bonding area between the bumps 7 and the circuit board electrodes 11;
Spreading of the Ag paste during bonding caused bonding failures. In addition, there is a risk of short-circuiting with adjacent bumps, which has been an obstacle to reducing the pad pitch.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a semiconductor device mounting method that can eliminate the above-mentioned problems, prevent connection failures due to spread of adhesive during bonding, and reduce pad pitch. do.

[0009]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a method for mounting a semiconductor element on a circuit board using a wireless bonding method, which includes a step of inserting a spacer into an adhesive, and a step of adding a spacer to an adhesive. The adhesive is applied to the bump surface of a semiconductor element, and the semiconductor element is mounted on a circuit board using the adhesive.

0010

[Operation] According to the present invention, in a method for mounting a semiconductor element on a circuit board using the wireless bonding method, a spacer is inserted into an adhesive, the adhesive is applied to the bump surface of the semiconductor element, and the adhesive is applied to the bump surface of the semiconductor element. Then, the bumps of the semiconductor element are connected to the electrodes of the circuit board, and the semiconductor element is mounted on the circuit board.

[0011] Therefore, it is possible to prevent connection failures due to spread of adhesive during bonding, and to reduce the pad pitch.

0012

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of a mounting process of a semiconductor element by a wireless bonding method, showing an embodiment of the present invention. First, as shown in FIG. 1(a), bump 2
The semiconductor element 21 on which 2 is formed is bonded to a conductive adhesive resin such as Ag paste 23 with spacers 24 (several thousand Å to several μm).
Place it on top of the mixed adhesive 25.

Next, as shown in FIG. 1(b), the bump 2
Adhesive 25 is applied onto the 2 surfaces. At this time, bump 2
2. Prevent the adhesive 25 from getting on parts other than the surface. Next, as shown in FIG. 1C, the semiconductor element 21 with the adhesive 25 attached thereto is aligned using a well-known method, and the bumps 22 are positioned on the electrodes 27 on the circuit board 26.

Next, as shown in FIG. 1(d), the bumps 22 of the semiconductor element 21 with the adhesive 25 on them are hardened by applying heat while pressurizing them onto the electrodes 27 on the circuit board 26. With this configuration, as shown in FIG. 2(b), the electrodes and bumps of the circuit board can be reliably electrically connected via the Ag paste, and the semiconductor element can be connected to the circuit board. Implementation can be done. Here, since the adhesive 25 contains the spacer 24, the spacer 24
Compared to the conventional case where 4 is not included, the spread width is smaller.

FIG. 2 is an enlarged cross-sectional view of a bonding part during mounting of a semiconductor element, FIG. 2(a) is a cross-sectional view of a conventional semiconductor element, and FIG. 2(b) is a cross-sectional view of a semiconductor element according to the present invention. It is a diagram. In FIG. 2A, the spread width of the Ag paste 9 is a, and the distance (or height) between the bottom surface of the bump and the top surface of the electrode is a'. In FIG. 2(b), the adhesive 25
The width of the bump is b, and the distance (or height) between the bottom surface of the bump and the top surface of the electrode is b'.

A spacer 24 is attached to the adhesive 25 in FIG. 2(b).
are mixed, the following inequalities hold between the above four parameters: a>b...(1) a'<b'...(2). If this inequality holds true, the occurrence of bonding defects will be reduced and the pad pitch can be further reduced.

[0017] The adhesive and curing method used may be other than the above-mentioned thermosetting type, for example, an ultraviolet curing type may be used to achieve the same effect. Further, the present invention is not limited to the above embodiments, and various modifications can be made based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0018]

As described in detail above, according to the present invention, the following effects can be achieved. In a method for mounting a semiconductor element on a circuit board, when connecting bumps on the semiconductor element and electrodes on the circuit board, for example, A
I applied an adhesive such as g-paste mixed with a spacer to the bump surface to make the connection.
It is possible to prevent connection failures due to spread of adhesive during bonding.

Furthermore, the pad pitch can be reduced.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a semiconductor element mounting process by a wireless bonding method showing an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a bonding portion when a semiconductor element is mounted.

FIG. 3 is a cross-sectional view of a conventional process for forming Au bumps on a semiconductor device.

FIG. 4 is a cross-sectional view of a conventional mounting process of a semiconductor element having bumps on a circuit board.

[Explanation of symbols]

21 Semiconductor device 22 Bump 23 Ag paste 24 Spacer 25 Adhesive 26 Circuit board 27 Electrode

Claims (1)

[Claims] 1. A method for mounting a semiconductor element on a circuit board using a wireless bonding method, comprising: (a) adding a spacer to an adhesive; (b) applying the adhesive to a bump surface of a semiconductor element. (c) mounting the semiconductor element on a circuit board via the adhesive.