JPH0214553A - Semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a semiconductor device which has a perfect protective function and whose reliability is high by a method wherein a protective film is made to be a two-layer structure and an oxide film is constituted in such a way that it is separated, on the surface of a bonding pad, from a packaging material by using a nitride film. CONSTITUTION:In a semiconductor device, a silicon oxide film 7 is deposited on the surface of a semiconductor chip 1 where a bonding pad 3 has been formed; the surface is coated with a resist 9; after that, the resist is patterned; a prescribed region is etched by making use of the resist 9 as a mask; an opening part 11 is formed. In addition, a silicon nitride film 8 is deposited on the surface of the bonding pad 3 and on the surface of the silicon oxide film 7; the resist 9 is coated again; after that, the resist is patterned; the silicon nitride film 8 is etched down to the surface of the bonding pad 3; an opening part 10 for wiring use is formed; a wire 4 is bonded to the surface of the bonding pad 3 exposed at the inside; lastly, the semiconductor chip 1 and one part of the lead frame 2 are molded by a resin material 5. Accordingly, a protective function is maintained sufficiently; the semiconductor device of high reliability can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device, and particularly to a structure of a passivation film on a bonding pad.

[Prior Art] A semiconductor device is manufactured by enclosing a semiconductor chip in a package for convenience in handling and mounting on a wiring board. FIG. 2 is a cross-sectional structural diagram showing an example of a packaged semiconductor device. Furthermore, Fig. 3 shows the arrow direction ■ in Fig. 2.
A cross-sectional view from the direction is shown. The semiconductor chip 1 is bonded to the chip mounting portion 2a of the lead frame 2. Bonding pads 3 are formed in the peripheral region of the surface of the semiconductor chip 1 . The bonding pad 3 is connected to the lead 2b of the lead frame by a wire 4 made of aluminum (AFL), gold (Au), or the like.

Thereafter, the lead frame 2 and the semiconductor chip 1 are molded and sealed with a resin material 5 except for the lead ends 2b.

FIG. 4 shows a cross-sectional structure in the vicinity of the bonding pad 3 as viewed from the direction of the arrow {circle around (2)} in FIG. A passivation film 6 is formed on the surface of the semiconductor chip 1. The passivation film 6 plays the role of stabilizing the electrical characteristics of the semiconductor surface and the role of protecting the element from coloring in the external atmosphere.

And passivation! i6 is generally a silicon oxide film (S i 02 ) or a silicon nitride film (SiN).
has been used. However, when using a silicon nitride film, its high dielectric constant has become a problem as semiconductor device structures have become smaller, and film stress due to differences in thermal expansion with the semiconductor substrate has become a problem. This has caused problems with reliability.

On the other hand, when using a silicon oxide film, it is more effective than a silicon nitride film in terms of film stress and dielectric constant problems, but it has poor moisture resistance and external sodium (Na)
It is inferior to silicon nitride film in its barrier properties against the intrusion of contaminants such as.

Therefore, a new passivation film having a two-layer structure in which a silicon oxide film and a silicon nitride film are laminated has been proposed. This structure will be explained using FIGS. 5A to 5C. This figure shows the cross-sectional structure of the semiconductor chip 1 in the vicinity of the bonding pad 3 according to the passivation film manufacturing process.

First, as shown in FIG. 5A, a silicon oxide film 7 is formed on the surface of the semiconductor chip 1 on which the bonding pads 3 are formed, and a silicon nitride film 8 is further formed thereon.

Next, as shown in FIG. 5B, a resist is applied and patterned, and the silicon nitride film 8 and silicon oxide film 7 are etched using the resist 9 as a mask.

Through this step, a wiring opening 10 in which the surface of the bonding pad 3 is exposed is formed.

Further, as shown in FIG. 5C, after removing the resist 9, a wire 4 made of Afl, Au, or the like is bonded to the bonding pad 3. Thereafter, the resin material 5 is molded and sealed into a package.

In this way, the two layers of silicon oxide film 7 and silicon nitride film 8 formed on the surface of semiconductor chip 1 constitute a passivation film. The silicon oxide film 7 that is in direct contact with the surface of the semiconductor chip 1 protects the electrical characteristics of the semiconductor surface due to its low dielectric constant and low generation of film stress. Further, the silicon nitride film 8 has excellent barrier properties and effectively prevents contaminants from entering from the resin material 5 and the like.

[Problems to be Solved by the Invention] However, as shown in FIG. 5C, in the conventional two-layer passivation film, the silicon oxide film 7 and the silicon nitride film are separated inside the wiring opening 10 on the bonding pad 3. There was a region where the exposed cross section of the membrane 8 and the resin material 5 were in direct contact. As mentioned above, since the silicon oxide film 7 has low barrier properties, there are problems such as sodium, moisture, etc. entering the silicon oxide film 7 from the resin material 5 for the package and impairing the stability of the semiconductor surface. occured.

Furthermore, the stress from the resin material 5 acts directly on the silicon oxide film 7 in this contact region, causing problems such as weakening the stress reduction effect and deteriorating the reliability of the semiconductor device.

Therefore, the present invention has been made to solve the above problems, and provides a highly reliable semiconductor device equipped with a two-layer structure passivation film that has a complete protection function even on the bonding pad of a semiconductor chip. The purpose is to provide

[Means for Solving the Problems] A semiconductor device of the present invention has a protective film on the surface of a semiconductor chip on which an integrated circuit is formed, and connects bonding pads formed on the surface of the semiconductor chip and a lead frame. This is a resin-sealed semiconductor device in which the entire periphery of the semiconductor chip is covered and sealed with a packaging material, and the protective film consists of an oxide film formed on the surface of the semiconductor chip and a nitride film formed on this surface. Furthermore, on the surface of the bonding pad, the oxide film is separated from the package material by a nitride film.

[Function] The passivation film of the two-layer stacked structure of the semiconductor device according to the present invention is formed on the surface of the bonding pad so that the upper nitride film completely covers the open end surface of the lower oxide film. Therefore, the lower oxide film is completely blocked from contacting the package resin material by the upper nitride film. This prevents contaminants from entering the oxide film from the resin material. Furthermore, the nitride film alleviates the stress generated by the resin material, thereby preventing the stress from being transmitted to the inside of the semiconductor chip.

[Example code] An embodiment of the present invention will be described below with reference to the drawings.

1A to 1E show a cross-sectional structure mainly in the vicinity of a bonding pad of a semiconductor device having a two-layer passivation film according to the present invention, according to its manufacturing process. The structure of a passivation film of a semiconductor device will be described below with reference to this figure.

First, as shown in FIG. 1A, a silicon oxide film 7 is deposited on the surface of the semiconductor chip 1 on which the bonding pads 3 are formed.

Next, as shown in FIG. 1B, a resist 9 is applied on the surface of the silicon oxide film 7, and then patterned, and further, using this resist as a mask, a predetermined region of the silicon oxide film 7 deposited on the bonding pad 3 is etched. Then, the opening 11 is formed. Furthermore, as shown in FIG. 1C, a silicon nitride film 8 is deposited on the surface of the bonding pad 3 and the silicon oxide film 7.

Thereafter, as shown in FIG. 1D, a resist 9 is applied again onto the silicon nitride film 8, followed by buttering, and using the resist 9 as a mask, the silicon nitride film 8 is etched until it reaches the surface of the bonding band 3. Through this step, the wiring opening 10 is formed. This wiring opening 10 is formed so that the opening distance on one side is approximately 2 μm or more smaller than the opening 11 formed in the silicon oxide film 7 in the previous step. As a result, the cross-sectional area of the opening 11 formed in the silicon oxide film 7 on the surface of the bonding pad 3 is completely covered with the silicon nitride film 8 having a thickness of 2 μm or more.

Further, as shown in FIG. 1E, the wiring opening 1
All on the surface of the bonding pad 3 exposed inside the
Then, finally, a part of the semiconductor chip 1 and lead frame 2 is molded with a resin material 5 to complete a packaged semiconductor device.

In this way, as shown in FIG. 1E, the silicon nitride film 8
is formed on the bonding pad 3 so as to cover the opening end surface of the silicon oxide film 7. Therefore, contact between silicon oxide film 7 and resin material 5 is completely interrupted. This prevents contaminants from entering the silicon oxide film 7 from the resin material 5, and the stability of the semiconductor layer by the silicon oxide film 7 is maintained. Furthermore, resin material 5
The silicon nitride film 8 can alleviate the stress caused by the silicon oxide film 7 and prevent the stress from being directly transmitted to the semiconductor chip 1 via the silicon oxide film 7. These effects can improve the reliability of the semiconductor device.

Note that the present invention can be applied to all semiconductor devices in which a passivation film is formed on the surface of a semiconductor chip.

[Effects of the Invention] As described above, in the semiconductor device of the present invention, an oxide film with excellent stress resistance properties is formed as a first layer on the surface of a semiconductor chip, and a nitride film with excellent barrier properties is formed as a second layer. By depositing it, the collector circuits etc. formed on the semiconductor chip are protected.

Furthermore, the first layer of oxide film on the surface of the bonding pad is separated from the packaging material by the second layer of nitride film, which has excellent barrier properties, so the protective function is sufficiently maintained and the reliability is high. A semiconductor device can be realized.

[Brief explanation of the drawing]

Figures 1A, 1B, 1C, 1D and 1E
The figure is a cross-sectional structure diagram mainly showing a cross-sectional structure of a region near a bonding pad according to the manufacturing process in a semiconductor device according to an embodiment of the present invention. FIG. 2 is a cross-sectional structural diagram of a general resin-packaged semiconductor device. FIG. 3 is a cross-sectional view taken in the direction along the arrow {circle around (2)} in FIG. 2. Figure 4 shows the arrow direction in Figure 3.
FIG. Figure 5A, 5th
FIG. B and FIG. 5C are cross-sectional structural diagrams showing the cross-sectional structure near the bonding pad of a conventional semiconductor device according to the order of manufacturing steps. In the figure, 1 is a semiconductor chip, 3 is a bonding pad, 4 is a wire, 5 is a resin material, 7 is a silicon oxide film, 8 is a
indicates a silicon nitride film. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] A protective film for protecting the integrated circuit is provided on the surface of a semiconductor chip on which an integrated circuit is formed, and a bonding pad formed on the surface of the semiconductor chip is connected to a lead frame, Furthermore, in a resin-sealed semiconductor device in which the entire periphery of a semiconductor chip is covered and sealed with a packaging material, the protective film includes an oxide film formed on the surface of the semiconductor chip and a nitride film formed on the oxide film. A semiconductor device having a two-layer structure with a film, and on a surface of the bonding pad, the oxide film is separated from the package material by the nitride film.