JPS63269538A - Semiconductor device - Google Patents

Abstract

PURPOSE:To enhance the reliability by a method wherein a bonding pad part which is opened in a first surface protective film formed on a substrate is installed and a second surface protective film of high dampproofness is covered on the whole surface of the first surface protective protective film including a side face of an opening in the first protective film with a view to preventing the moisture from penetrating from the side face of a passivating film. CONSTITUTION:An aluminum film 2 to be used for a bonding pad is formed on a substrate 1; a first protective film composed of a PSG film 3 is applied to the whole surface excluding the bonding pad part. In addition, a second protective film of a silicon nitride film 4 is coated on the PSG film 3 in such a way that the film can cover a side face of this PSG film 3 in order to prevent moisture penetration from the end face of the PSG film 3. The PSG film 3 is etched and a resist is stripped from the whole surface; after that, the silicon nitride 4 is grown. Then, a resist is coated on this silicon nitride film 4; after that, this assembly is exposed to light by making use of a mask whose opening is smaller than an etching opening of the PSG film 4 and is then developed; the silicon nitride film 4 is etched by making use of the resist as the mask in such a way that it is left by more than 1.5 times a growth film thickness if the silicon nitride film 4 in a transverse direction from the end of the PSG film 3.

Description

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

[Conventional technology]

Semiconductor devices usually include a passivation film on the surface of the semiconductor element in order to stabilize the characteristics.
After forming a semiconductor element thereon, an aluminum film 2 for a bonding pad is formed, and a phosphorus silicate glass film (hereinafter referred to as a PSG film) 3 is deposited on top of the aluminum film 2. In order to compensate for the inferiority of this PSG film 3 in terms of moisture resistance, this PSG film 3
A highly moisture-resistant protective film such as a silicon nitride (SiN4) film 4 is coated on top of the film, and this is selectively etched using a photoresist as a mask to form a bonding opening.

The side surface of the PSG film 3 at this bonding pad opening is
The highly moisture-resistant protective film was not covered and was exposed.

[Problem that the invention seeks to solve]

In the conventional structure described above, the upper surface of the passivation film has sufficient element strength against moisture, but the side surface has sufficient resistance to moisture.
The end face of the G film 3 is exposed, and the elemental force of moisture is not necessarily perfect, so the moisture collects PSGSaO2, generates phosphoric acid (82PO4), and dissolves the aluminum Jfi 2 in the bonding pad area. There are drawbacks. This has been a major factor in significantly reducing the reliability of semiconductor devices.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate such drawbacks, prevent moisture from entering from the side surfaces of the passivation film, and provide a semiconductor device with improved reliability.

[Means for solving problems]

The structure of the present invention includes providing a pattern of a conductive film on a substrate,
A first surface protection film made of phosphorous silicate glass or the like is provided on the substrate including the conductive film, a bonding pad portion having an opening is provided in the first surface protection film, and a high The present invention is characterized in that a moisture-resistant second surface protection film is coated on the entire surface of the first surface protection film, including the side surfaces of the openings of the first surface protection film.

〔Example〕

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a vertical cross-sectional view showing a bonding pad portion of a semiconductor device according to an embodiment of the present invention.A bonding pad aluminum film 2 of this embodiment is formed on a substrate 1, and a PSG
A first protective film made of SaO2 is coated over the entire surface except for the bonding pad portion. Furthermore, this PSGSaO2 is formed on the PSG film 3 by the second protective film of the silicon nitride film 4.
It covers the entire surface of the PSGSaO2 surface to prevent moisture from entering from the surface.

In this structure, a semiconductor element is first manufactured on a substrate 1, 200 to 10,000 PSGSaO layers are grown thereon to serve as a protective film, and an opening is created for bonding a bonding wire to an aluminum M2 for a bonding pad. Therefore, PSGS
A resist is applied to aO2, exposed and developed, and the resist on the bonding pad aluminum M2 is removed. Thereafter, PSGSaO2 is applied to the aluminum crotch for the bonding pad using a hydrofluoric acid-based chemical solution, and after the resist is removed from the entire surface, 500 to 10,000 silicon nitrides 4 are grown. After applying a resist on this silicon nitride film 4, exposure and development are performed using a mask with an opening smaller than the etching opening of PSG[4. This is obtained by etching the silicon nitride film 4 so that it remains 1.5 times or more thicker than the grown silicon nitride film 4, and then peeling off the resist on the entire surface.

〔Effect of the invention〕

As described above, the present invention has the effect of preventing moisture from penetrating into the side surfaces of the PSG film in the bonding pad portion by covering the PSGSaO2 surface with a silicon nitride film (Si3N4)4 or the like as a highly moisture-resistant protective film. For this reason, P.S.
GSaO2 does not infiltrate and generate phosphoric acid, etc. due to chemical reactions within the PSG film, and the bonding pads and internal aluminum are melted, causing loss of aluminum from bonding pads and cross sections of internal wiring. It has the effect of preventing

For example, conventionally, after 500 hours of storage at 1 to 3 atmospheres, 100 to 150 degrees Celsius, and 100% relative humidity, phosphoric acid is reacted and generated in the PSG film due to moisture intrusion from the periphery of the pad, and the aluminum is dissolved. As a result, the number of internal wiring breakages occurred approximately 1 ppm relative to the number of semiconductor devices stored. On the other hand, with the structure of the present invention, no defects occurred in the semiconductor device under similar storage conditions. Therefore, according to the present invention, a highly reliable semiconductor device can be obtained.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of an example of a conventional semiconductor device. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Aluminum film for bonding pads, 3... Phosphorus silicate glass film, 4... Silicon nitride film.

Claims (1)

[Claims] A pattern of a conductive film is provided on a substrate, a first surface protection film such as phosphorous silicate glass is provided on the substrate including the conductive film, and a bonding pad portion having an opening is provided in the first surface protection film. , characterized in that a highly moisture-resistant second surface protective film is coated on the first surface protective film over the entire surface of the first surface protective film, including the side surfaces of the openings of the first surface protective film. semiconductor devices.