JPH02110948A - Semiconductor device and its mounting - Google Patents

Abstract

PURPOSE:To increase the degree of deformation of bump electrodes due to pressing in the case of mounting and to contrive to make possible an increase in the density of the mounting without causing the failure of an electrical connection by a method wherein a semiconductor element provided with the bump electrodes, whose sectional configurations in their thickness directions are formed into an almost quadrangle and whose sizes are made smaller than their thicknesses, is connected to a wiring board. CONSTITUTION:An insulating substrate 7 having conductor wirings 8 and a semiconductor element (an LSI chip) 10 provided with bump electrodes 6, which have one side or a diameter smaller than their thicknesses and have an almost quadrangular section in their thickness directions, are fixed to each other with an insulative resin 9 in such a way that the wirings 8 and the electrodes 6 are made to coincided with each other and they electrically come into contact and are connected to each other. Moreover, the resin 9 is applied on the parts of the wirings 8 provided on the wiring board 7 and after the element 10 provided with the electrodes 6, which have one side or a diameter smaller than their thicknesses and have an almost quadrangular section in their thickness directions, is fixed by pressure making their electrodes 6 coincide with the wirings 8 on the region of the resin 9 spread on the board 7, the resin 9 is hardened and with the element 10 fixed on the board 7, the wirings 8 and the electrodes 6 are electrically connected to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a semiconductor device and its mounting method, and particularly relates to a method of mounting a multi-electrode, narrow-pitch LSI chip used in microcomputers, gate arrays, etc. .

(Prior Art) Conventionally, in the field of manufacturing semiconductor devices, there is a mounting technique called MBB (micro bump bonding) in which a semiconductor element such as an LSI chip is face-down and surface-mounted directly onto a circuit board.

Figure 3 shows an LSI mounted using the MBB mounting technology.
FIG. 3 is a process cross-sectional view showing the formation of protruding electrodes on the chip.

First, as shown in FIG. 3(a), the LS as a semiconductor element
A protective film 23 is provided on the surface of the semi-quartet wafer 21 on which the I-chip is formed and has the electrode 22, and is made of Ti-Pd-Au.

A barrier metal 24 such as Cr-Au is formed by vapor deposition, and then a plating resist 25 is formed by photolithography. Note that the thickness is usually about 1 μl to 2 μl.

Thereafter, as shown in the figure (b), protruding electrodes 26 are formed by auto-electroplating, and then, as shown in the figure (c), unnecessary portions of the barrier metal 24 are removed by photoetching. . Here, the thickness of the protruding electrode 26 is 10
μm to 30μm, size is 50μmφ to 100
The pitch is approximately 100IJ11 to 300μm, and the cross-sectional shape is shown in the same figure (c). If the thickness of the plating resist is 25 or more (height in the figure), the plating will grow in the lateral direction as well. Therefore, it has an angular shape with a bottom protrusion.

In such a bump shape, when miniaturizing the protruding electrodes 26 for high-density mounting, the bottom dimension must be made extremely small, but this inevitably reduces the strength of the electrodes. Since the plating grows laterally, it is necessary to reduce the thickness with miniaturization, which reduces the degree of deformation of the protruding electrodes when pressure is applied during mounting on the wiring board, and improves the connection with the conductor wiring on the wiring board. This will cause poor contact.

FIG. 4 is a diagram showing the process of mounting the LSI chip formed as described above on a wiring board, and the reference numerals 21 to 26 are the same as those in FIG. 3.

First, in FIG. 4(a), 27 is a wiring board on which an LSI chip is mounted, and is made of ceramic, glass, etc., and conductive wiring 28 on which the LSI chip is mounted and connected.
An ultraviolet (hereinafter abbreviated as UV ray) curable or thermosetting insulating resin 29 is applied as shown in the figure. The conductor wiring 28 is made of Cr-Au.

^D, Cu, ITO(Indium Tin
For the insulating resin 29, an epoxy resin, an acrylic resin, or the like is used.

Next, as shown in the same figure (b), a protruding electrode 2 made of Au etc.
6 is mounted with its protruding electrodes 26 and conductor wiring 28 facing each other and aligned, and mounted on the wiring board 2.
The pressure tool 31 is used to press the area where the insulating resin 29 of No. 7 is applied. At this time, the protruding electrodes 26 of the LSI chip 30 are plastically deformed, and at the same time, the insulating resin 29 interposed between the protruding electrodes 26 and the conductor wiring 28 is pushed out around the protruding electrodes 26, so that the protruding electrodes 26 and the conductor wiring 28 are electrically be contacted and connected to. After curing the insulating resin 29 in this state,
If the pressure tool 31 is removed as shown in FIG. 3(c), the LS
The I chip 30 is a hardened insulating resin 29 on the wiring board 27.
At the same time, the deformed protruding electrode 26 and the conductor wiring 28 are fixed while maintaining good electrical contact, and the LS
The mounting of the I-chip 3o onto the wiring board 27 is completed.

(Problems to be Solved by the Invention) Conventionally, as mentioned above, when mounting semiconductor elements such as LSI chips, the protruding electrodes 26 are formed using the plating resist 25 which is much thinner than the protruding electrodes (FIG. 3). When attempting to miniaturize the protruding electrodes in response to the mounting of narrow-pitch, multi-pin LSI chips, there are problems as described below.

(a) It is necessary to make the size of the protrusion on the bottom surface of the protruding electrode, that is, the size of the opening in the plating resist, extremely small, and in this configuration, the degree of adhesion between the protruding electrode and the barrier metal and the strength of the protruding electrode decrease.

(b) Since the plating during the formation of the protruding electrodes also grows in the lateral direction, the thickness of the protruding electrodes becomes thinner, resulting in insufficient deformation when pressurizing the wiring board, which reduces the thickness of the protruding electrodes in the LSI chip. Variations and imbalances in the flatness of the wiring board cannot be absorbed by deformation of the protruding electrodes, resulting in poor electrical contact.

(c) In order to avoid the poor contact described in (b) above, if the thickness of the protruding electrode is increased, it will be difficult to miniaturize the protruding electrode, and it will not be possible to cope with semiconductor devices with a large number of pins or a narrow pitch. When the pitch is 10 μm, the size of the protruding electrode is limited to 25 μl, making it difficult to support LSIs with a pitch of 50 μm or less.

An object of the present invention is to provide a method for mounting a semiconductor device that solves the above-mentioned problems.

(Means for Solving the Problems) The present invention has achieved the above-mentioned objects by making the thickness of the plating resist at the time of forming the protruding electrodes to be approximately the same as the thickness of the protruding electrodes, and making the cross-sectional shape of the protruding electrodes in the thickness direction approximately square. This is achieved by connecting the LSI chip to the wiring board using protruding electrodes that are smaller in size.

(Function) According to the present invention configured as described above, the thickness of the plating resist is approximately the same as the thickness of the protruding electrode even by miniaturization of the protruding electrode, so that the plating does not grow in the lateral direction as in the conventional method. Therefore, a protruding electrode with a large thickness and a small size can be obtained, which increases the degree of deformation due to pressure when mounting an LSI chip as a semiconductor element on a wiring board, and therefore leads to poor electrical connection. This makes it possible to increase the density of packaging without causing problems.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of the process of forming a protruding electrode according to an embodiment of the present invention, and FIG. 2 is a diagram showing a method of mounting an LSI chip on a wiring board.

First, as shown in FIG. 1(a), a protective film 3 is provided on the surface of a semiconductor wafer 1 on which an LSI chip is formed, and a barrier metal 4 such as Ti-Pd-Au, Cr-Au, etc. is provided. is formed by vapor deposition, and then a plating resist 5 is formed by photolithography. The thickness of barrier metal 4 is normal.

The thickness of the plating resist 5 is about 10 μm to 20 μI, and the size is about 5 μm to 1.0 μm.
It is approximately μ to 15μ φ.

The plating resist 5 can have a thickness of 10 .mu.l to 20 .mu.m by using a positive resist with high viscosity or the like by -times of spin cord. In addition, exposure is performed by contact exposure, projection exposure, etc., and the wavelength used is 3fr5nm.
However, the exposure amount is about 300 mJ to 450 mJ when the thickness of the plating resist is 10 μI and the size is 10 μmφ.

Next, as shown in FIG. 6(b), Au is electroplated to form the protruding electrode 6, but the plating is done up to the surface of the plating resist 5, the thickness of the protruding electrode 6 is made equal to the plating resist 5, and the plating is done until the surface of the plating resist 5 is aligned. This prevents the protrusion electrode 6 from growing in the lateral direction, thereby avoiding an increase in the size of the protrusion electrode 6.

Metering current density is 0.03IIA/+a2 and 1Op11
It takes about 40 minutes to obtain a thickness of .

Next, as shown in FIG. 4C, the plating resist 5 is removed, and unnecessary portions of the barrier metal 4 are removed by photo-etching to obtain protruding electrodes 6.

According to this method, the protruding electrode 6 has a thickness of 10 μm and a thickness of 3 μm.
It is possible to form protruding electrodes 6 with a pitch of 5 μI to 10 IAm, and it is possible to form protruding electrodes 6 with a pitch of 5 μI to 10 IAm, which is sufficient for LSI chips with a large number of pins and a narrow pitch.

A method for mounting the LSI chip formed as described above onto a wiring board will be explained with reference to FIG.

First, as shown in FIG. 2(a), an insulating resin 9 is applied to a region of the wiring board 7 made of glass, ceramic, etc., including the conductor wiring 8. As shown in FIG. The thickness of the wiring board 7 is about O.lon to 2.0 mm, and the conductor wiring 8 is made of Cr-Au, A
It is formed of D, ITO, etc., and has a thickness of about 0.1 μm to 1060 μI. Further, as the insulating resin 9, a photocurable or thermosetting resin such as acrylic or epoxy is used, and the coating is performed using a dispenser, printing, or the like.

Next, as shown in the same figure (b), an LSI is formed of Au, Al1, etc. and has a protruding electrode 6 whose bottom dimension is smaller than its thickness.
The chip 10 is mounted on the area where the insulating resin 9 is applied, with the protruding electrodes 6 and the conductor wirings 8 aligned. The thickness of the protruding electrode 6 is about 10 μm to 20 μI, and the dimension is 5 μm.
The diameter is approximately 15 μm to 15 μm. Moreover, the pitch is about 10 μm to 100 μm.

Next, the LSI chip 10 is pressurized with a force of approximately 0.5 g to 5 g per electrode using the press tool 11. At this time, the insulating resin 9 interposed between the protruding electrode 6 and the conductor wiring 8 is extruded, and the protruding electrode 6 and the conductor wiring 8 are electrically contacted and connected. At this time, since the protruding electrode 6 is thicker than its dimensions, it is easily deformed, and variations in its thickness and imbalance in the flatness of the wiring board 7 are absorbed, allowing connection and mounting of hundreds or thousands of pins. Also, electrical connections with high yield can be easily obtained.

Next, in the pressurized state, the insulating resin 9 is
If it is a V-ray curable resin, depending on whether the wiring board 7 is transparent or opaque, UV rays are irradiated from the back side of the wiring board 7 or from the side of the T or SI chip 10 to cure the resin. After the resin has hardened, if the pressure tool 11 is removed as shown in FIG. A semiconductor device in which 10 is firmly fixed is formed.

Note that the LSI chip 0 is fixed to the wiring board 7 by the insulating resin 9 using T A B (Tape Auto
tedllondjng).

(Effects of the Invention) As is clear from the above detailed explanation, the present invention provides that the protruding electrode is formed by plating using a plating resist of the same extent as the I corner of the protruding electrode. Since the cross-sectional shape in the thickness direction is approximately rectangular and the thickness is larger than the bottom dimension, it has the following effects.

(a) Since there is no lateral growth due to plating in the formation of protruding electrodes, fine protruding electrodes are formed with a sufficiently thin thickness of I'X, for example, with a thickness of 10 μm and dimensions of 3 μIφ to 5 μlφ. This makes it possible to connect and package at a pitch of 10 μm or less, making it possible to achieve high-density packaging that is approximately one order of magnitude higher than that of conventional methods.

(b) Since the protruding electrode is thicker than the bottom dimension, L
The SI chip is easily deformed when pressure is applied, and variations in the dimensions of protruding electrodes or imbalances in the flatness of the wiring board are absorbed with extremely small loads, so hundreds to thousands of pins can be formed without damaging the LSI chip. It is possible to connect and mount several LSI chips, and it is possible to easily perform high-density mounting of LSIs.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the process of forming protruding electrodes according to one embodiment of the present invention, FIG. 2 is a sectional view showing the LSI chip mounting process of one embodiment, and FIG. 3 is a sectional view showing the conventional process of forming protruding electrodes. 4 is a cross-sectional view illustrating a conventional LSI chip mounting process. DESCRIPTION OF SYMBOLS 1... Semiconductor wafer, 2... Electrode, 3... Protective film, 4... Barrier metal, 5... Metsukiresis 1~. 6... Projection electrode, 7... Wiring board, 8
...Conductor wiring, 9...Insulating resin, 10...L
SI chip, 11...pressure tool. Rod, 4-ma diagram patent applicant Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] (1) An insulating substrate having a conductive wiring and a semiconductor element provided with a protruding electrode having an approximately rectangular cross section in the thickness direction with one side or diameter smaller than the thickness, by aligning the conductive wiring and the protruding electrode. , a semiconductor device characterized in that they are fixed with an insulating resin so that they are electrically connected. (2) The semiconductor device according to claim (1), wherein the protruding electrode has a substantially rectangular cross section in the thickness direction, and the length or diameter of one side of the cross section is smaller than the thickness. (3) The process of applying insulating resin to the conductor wiring portion of the wiring board, and the step of applying an insulating resin to the conductor wiring portion of the wiring board, and attaching the semiconductor element with a protruding electrode having an approximately rectangular cross section in the thickness direction with one side or diameter smaller than the thickness. a step of matching and crimping the conductor wiring in the insulating resin area applied to the wiring board;
A method for mounting a semiconductor device, comprising the steps of curing the insulating resin, fixing the semiconductor element to the wiring board, and electrically connecting the conductor wiring and the protruding electrode.