JPH0334651B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a semiconductor device used in various electronic devices.

Conventional Structures and Their Problems Conventionally, various methods have been devised for handling semiconductor elements in chips as a means of packaging semiconductor devices on circuit boards in the smallest size possible. One of these is the flip chip, in which protruding electrodes (bumps) are provided on the electrode portion of a semiconductor chip, that is, an aluminum pad, using a metal thin film and solder plating, and the semiconductor chip is mounted face-down onto a circuit board. be. To manufacture this flip chip, first, a metal that has good adhesion to aluminum, such as titanium or chromium, is formed on the entire surface of the device including the aluminum pad by vapor deposition. Next, after depositing a good conductor such as copper on the same surface, photoresist is applied to the entire surface, only the aluminum pad is removed, and tin and lead are electroplated to an appropriate thickness using the underlying metal as an electrode. After plating, the resist is peeled off, and then a photoresist is applied to the tin and lead parts and the underlying metal film is removed by etching. After peeling off this photoresist, the tin and lead plating layer is melted to form solder. The semiconductor element chip produced in this manner is placed on a circuit board and heated to be soldered to the electrodes on the circuit board to establish an electrical connection. This method requires complicated processes such as thin film formation by vapor deposition, solder formation by electroplating, and resist film formation and etching by photolithography. A large amount is required, and the spacing between aluminum pads must be 200 to 300 microns.
As mentioned above, flip chips have the same mounting area as the chip, making them an effective means for high-density packaging. However, as mentioned earlier, the manufacturing process is extremely complex, leading to lower product yields and higher chip costs. On the other hand, flip-chip processing requires processing by the semiconductor manufacturer and is not possible by the user. In addition, flip chips are mounted on a circuit board by soldering, and when mounting directly on a circuit board, such as an ITO such as a liquid crystal panel, the ITO must first be metalized so that it can be soldered. First, panel costs will also increase in LCD panel manufacturing.

OBJECTS OF THE INVENTION An object of the present invention is to reduce the cost of semiconductor element chips and to provide a semiconductor device that can be directly mounted on a transparent conductive film used in a circuit board, particularly a liquid crystal panel, without metallization.

Structure of the Invention The present invention is characterized in that a conductive paint made of a photosensitive polyimide resin and a conductive metal oxide powder is formed on the aluminum electrode pad portion of a semiconductor element chip to be higher than the passivation film.

Description of Examples Examples of the present invention will be described below. First, to describe the features of the present invention, the most significant feature is that bumps are formed using conductive resin, and by utilizing the adhesive effect of the resin, electrical and mechanical connections can be made without metalizing the circuit conductors of the circuit board. It is to combine in a specific manner. The photosensitive resin is preferably acrylated polyimide resin, and the conductive powder is tin oxide,
Fine powder of indium oxide with a particle size of 0.1 micron or less is particularly effective in the present invention. This is because the fine powder of tin oxide and indium oxide has a small particle size and is smaller than the wavelength of light, so it has translucency and does not interfere with the photocuring of photosensitive resin, making it possible to form bumps with high precision. This is because it becomes possible. Generally used metal powders cannot be used in the present invention because it is difficult to make them into fine particles of 0.1 micron or less.

Next, one embodiment of the present invention will be described using the drawings.

In the figure, 1 is a silicon substrate, and on this silicon substrate 1, an aluminum pad portion 2 is formed by a method such as vapor deposition, and a passivation film 3 such as plasma nitride is further formed to constitute a semiconductor element chip. . Further, bumps 4 are formed on the aluminum pad portion 2 by applying a conductive paint made of photosensitive polyimide resin and conductive metal oxide powder, and the bumps 4 are formed on the aluminum pad portion 2.
Well formed and high.

A method of manufacturing a semiconductor device having such a configuration will be described below. First, 40 parts by weight of antimony-doped tin oxide powder is added to 100 parts by weight of the resin of a varnish made of polyimide resin and a solvent, and dispersed in a ball mill to form a paint. This is applied onto a semiconductor chip to a thickness of 5 to 50 microns, the aluminum pad portion 2 is exposed using a photomask, and the unexposed portion is removed by development to obtain a semiconductor device. This semiconductor device is used as a circuit board and aligned on a transparent electrode formed on the glass of a liquid crystal panel, and then bonded from the back side of the semiconductor device at 350° C. for 30 seconds and 35 kg/cm ² . At this time, there is no need to metalize the ITO of the transparent electrode, and the resin is completely cured by heating, resulting in strong adhesion and electrical connection. The height of the bump 4 should be such that sufficient pressure is applied to the bump 4 during the above-mentioned crimping.
Normally, a semiconductor chip is protected with a passivation film 3 made of plasma nitride or the like. The thickness is 0.8 to 1.0 microns, and the bump 4 according to the present invention needs to have a thickness greater than this, ideally a thickness that can absorb the unevenness of the circuit board. Specifically, as a result of experiments on various substrates, it has become clear that a good connection can be obtained if the thickness of the bump 4 is 5 microns or more. Also,
If the pad is thicker than 5 microns, the range of 50 microns is good, and if the pad spacing becomes, for example, about 100 microns, there is a risk of it being shot. This is because pattern accuracy deteriorates due to a fogging phenomenon during exposure.

Example The materials and formulations of the conductive paint were as follows, and they were mixed and dispersed in a ball mill to form a paint.

Polyimide resin (Toray Industries, Inc. Photonice)
...100 parts by weight tin oxide powder (Mitsubishi Metals Co., Ltd. T-1) ...35 parts by weight This paint was coated on a 4-inch wafer on which CMOS was formed using a spinner to a thickness of 10 microns at 85℃60 Pre-dried for a minute. Close exposure of photomask to this wafer (120W/cm
²⁾ using a UV lamp for 20 seconds) to remove the unexposed areas. After further drying the wafer at 100°C for 60 minutes,
The chips were cut into predetermined chip dimensions using a dicing saw to produce completed semiconductor devices. After aligning this semiconductor device with a circuit pattern formed with transparent electrodes on glass as a circuit board,
Electrical connection was made at the same time as pressure bonding to the glass plate under the conditions of 400° C., 30 Kg/cm ² , and 30 seconds. At this time, the chip size was 5 mm square, the number of pads was 64, the pushing strength in the lateral direction was 3.9 kg, and the tensile strength in the vertical direction was 2.1 kg. When the circuit was operated electrically, it was confirmed that it operated as expected.

Effects of the Invention The present invention has a structure in which a conductive and photosensitive paint is applied to a certain thickness on a wafer and bumps are formed on the aluminum pad, and this semiconductor device is thermocompression bonded to a circuit board to achieve a good quality. Adhesion and connection are obtained. According to this method, it is possible to directly mount the device on glass such as a liquid crystal panel without metalizing it into a transparent conductive thin film. In addition, bumps can be formed using a simple process, making it possible to significantly reduce costs, and because no special technology is required, bump technology that previously had to be processed by semiconductor manufacturers can now be handled by users. The fact that it is now possible to process semiconductors will contribute to the future semiconductor industry. In particular, the present invention uses a conductive paint consisting of a photosensitive polyimide resin and fine powder of tin oxide or indium oxide with a particle size of 0.1 micron or less. Since it is smaller than the wavelength, it has translucency and does not interfere with photocuring of the photosensitive resin, so bumps can be formed with high precision.

[Brief explanation of drawings]

The drawing is a sectional view showing an embodiment of the semiconductor device of the present invention. 1...Silicon substrate, 2...Aluminum parts, 3
... Passivation film, 4... Bump.

Claims (1)

[Claims] 1. A bump made of a conductive paint made of a photosensitive polyimide resin and a conductive metal oxide powder of tin oxide or indium oxide of 0.1 micron or less is formed on the electrode pad portion of a semiconductor chip at a height higher than the passivation film. semiconductor device.