JPH05183145A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To make it possible to avoid defect accompanied with multilayer wiring construction, to simplify the processes and enhance the quality and yield. CONSTITUTION:In the production method, a metal wiring region 4 and a bonding pad portion 5 connected through a contact hole 3 provided on the element of a semiconductor substrate 1 and an insulation film 2 are formed. Then, an intermediate insulation film 6 and a light-shielding film 13 are formed on the whole surface. The intermediate insulation film 6 is formed by a silicon oxide film, a PSG film, an opaque insulation film, etc. Then, the light-shielding film 13 is partially removed leaving a region to be light-shielded, a window is opened for a sensor light-receiving portion 11, and a light-shielding pattern 14 is formed. Thereafter, a protection film 12 consisting of the PSG film or a nitride film is formed on the light-shielding pattern 14; then, the intermediate insulation film 6 and protection film 12 on the bonding pad portion 5 and a scribe region 7 are removed by continuous or simultaneous etching; and an image sensor wafer is completed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device having a light shielding pattern such as an image sensor.

[0002]

2. Description of the Related Art As a semiconductor device provided with a light-shielding pattern, an image sensor such as a CCD is known, and its structure is disclosed in, for example, Japanese Unexamined Patent Publication No. 3-9563. As a method for manufacturing this type of semiconductor device, for example, Japanese Patent Laid-Open No. 294071/1990 discloses the manufacturing method, but in general, the manufacturing method is as shown in FIG.

In the manufacturing method shown in the same figure, as shown in FIG. 2 (a), a semiconductor substrate 1 of silicon or the like having a light receiving element or the like formed in advance on one main surface is used. First, this semiconductor substrate 1 is used. An insulating film 2 such as a silicon oxide film is formed on the surface of the. After forming this insulating film 2, a contact hole 3 is formed by removing a predetermined portion of the insulating film 2.

Then, pure aluminum or an Al--Si alloy containing a few percent of silicon is deposited on the insulating film 2 by sputtering or vapor deposition to form a metal film having a uniform thickness, and this metal film is subjected to lithography. The metal wiring region 4 is formed by removing only the necessary region using a technique. At this time, the bonding pad portion 5 for external connection is formed by the same method. Then, in order to secure the ohmic contact between the metal wiring region 4 and the semiconductor substrate 1, a heat treatment of heating at 400 to 500 ° C. is performed.

Next, as shown in FIG. 2B, an intermediate insulating film 6 made of a silicon oxide film, a PSG film or the like is formed on the surface including the metal wiring region 4 and the bonding pad portion 5 by CV.
The intermediate insulating film 6 formed by the D technique or the like and on the bonding pad portion 5 and the scrub region 7 is removed, and a window is opened.

Then, as shown in FIG. 2C, pure aluminum or an Al--Si alloy containing several% of silicon is deposited on the intermediate film 6 by sputtering or vapor deposition to form a light shielding pattern. The conductive metal film 8 is formed.

Next, as shown in FIG. 2D, the conductive metal film 8 is removed, leaving the portions of the light-shielding pattern region 9 and the bonding pad region 10 that require light-shielding. As a result, a predetermined light-shielding pattern in which the sensor light receiving unit 11 is opened is formed, and thereafter sintering is performed.

After that, as shown in FIG. 2 (e),
In order to protect the sensor from mechanical shock and moisture, a protective film 12 such as a PSG film or a nitride film is formed on the surface, the protective film 12 on the bonding pad region 10 and the scribe region 7 is removed, and a window is opened. The image sensor wafer is completed by performing. However, such a method of manufacturing a semiconductor device has the technical problems described below.

[0009]

That is, in the manufacturing method described above, since the bonding pad portion 5 has a multilayer wiring structure in which the conductive metal film 8 is formed on the first layer wiring metal film, If an oxide film remains on the surface of the first-layer wiring metal film of the pad portion 5 or if the conductive metal film 8 is formed with an alumina film formed on the surface, ohmic failure will occur.

Further, when the intermediate insulating film 6 is removed by etching, the etching rate of the specific pad is increased due to the cell effect, and the first layer wiring metal film of the bonding pad portion 5 becomes thin, and the wire is formed in this portion. At the time of bonding, there is a possibility that a problem of insufficient strength may occur, which hinders improvement in quality and yield.

The present invention has been made in view of the above conventional problems, and the object thereof is to:
It is an object of the present invention to provide a method for manufacturing a semiconductor device, which can avoid problems associated with a multi-layer wiring structure, simplify processes, and achieve improvement in quality and yield.

[0012]

In order to achieve the above object, the present invention has the following steps, which are performed in the following order in a method for manufacturing a semiconductor device having a light-shielding pattern.

Step: forming a metal wiring pattern for connecting elements provided on the semiconductor substrate through an insulating film.

Step: An intermediate insulating film is formed on at least one main surface over the metal wiring pattern.

Step: A light-shielding film is formed on at least one main surface of the intermediate insulating film.

Step: The light-shielding film is removed, leaving a region where light-shielding is required.

Step: A surface protective film made of an insulator is formed on at least one main plane of the light shielding film.

Step: The protective film and the intermediate insulating film are removed from the portions where the insulating film is unnecessary, such as the bonding pad portion and the scribe region.

In the above process, the insulating film can be an opaque insulator.

[0020]

According to the method of manufacturing a semiconductor device having the above structure, since the light-shielding film is formed on the intermediate insulating film in the process, it is possible to eliminate the need for punching and sintering once in the intermediate insulating film. In addition, since the light-shielding film is removed while leaving the region where light-shielding is necessary in the process, and the bonding pad part does not require light-shielding, the light-shielding film does not remain on the bonding pad part. Therefore, the degree of freedom of the material of the light shielding film is increased.

Further, according to the second aspect of the invention, since the light shielding film is an insulator, even if a pinhole is formed in the intermediate insulating film, a short circuit does not occur between the wiring metals.

[0022]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the following description, the same reference numerals will be used for parts that are the same as or correspond to those of the conventional manufacturing method shown in FIG. FIG. 1 shows an embodiment of a method of manufacturing a semiconductor device according to the present invention, in which FIG. 1 shows cross sections of manufacturing steps performed in order. In the manufacturing method shown in the figure, first, as shown in FIG.
As in the conventional case, a light receiving element, a control circuit element, and the like are previously formed on one main surface of the semiconductor substrate 1, and then the semiconductor substrate 1
An insulating film 2 such as a silicon oxide film is formed on the surface of the.

Then, the insulating film 2 at the portion where the electrode is taken out from the light receiving element or the like is removed, and the contact hole 3 is opened, and pure aluminum or Al-containing a few% of silicon is formed on the insulating film 2. Sputtering Si alloy,
Deposited by evaporation to form a metal film of uniform thickness,
This metal film is partially removed by a lithographic technique, and a metal wiring pattern for electrically connecting the elements is formed separately in the metal wiring region 4 and the non-wiring region.

At this time, a bonding pad portion 5 for external connection is formed on a part of the metal wiring region 4. Then, heat treatment is performed in order to ensure ohmic contact between the metal wiring region 4 and the semiconductor substrate 1. Although the above steps are the same as those in the conventional manufacturing method, the present invention is characterized by the following steps.

That is, in this embodiment, as shown in FIG. 1B, the intermediate insulating film 6 and the light-shielding film 13 are formed on the entire one main surface on the metal wiring pattern formed by the above process. It Here, the intermediate insulating film 6 is formed in the same manner as the conventional one.
A silicon oxide film or a PSG film is formed by the CVD technique,
The light-shielding film 13 does not need to be conductive as long as it is opaque, and aluminum, Al-Si which has been conventionally used may be used.
Besides, for example, polycrystalline silicon, resin, opaque insulating film, or the like can be adopted.

In this case, in particular, when an opaque insulating film is used as the light-shielding film 13, the light-shielding film is made of a conductive metal film in the conventional manufacturing method shown in FIG. If a hillock or the like occurs in the intermediate insulating film 6 and a pinhole is formed in the intermediate insulating film 6, there is a problem that the metal wiring region 4 and the light shielding film are short-circuited. However, the present invention eliminates such a problem at all.

Since there is no step of removing the intermediate insulating film 6 in the step shown in FIG. 1B, the light shielding film 13 is immediately formed continuously on the intermediate insulating film 6 by the sputtering technique by the sputtering technique. be able to.

After the formation of the light-shielding film 13, as shown in FIG. 1C, the light-shielding film 13 is partially removed, leaving a region for light-shielding, and the window of the sensor light receiving portion 11 is opened. By doing so, the light shielding pattern 14 is formed.

Then, as shown in FIG. 1D, a protective film 12 made of a PSG film or a nitride film is formed on one main surface of the light shielding pattern 14, and then as shown in FIG. Then, the intermediate insulating film 6 and the protective film 12 on the bonding pad portion 5 and on the scribe region 7 are removed by continuous or simultaneous etching to complete the image sensor wafer.

According to the method of manufacturing a semiconductor device which is performed in the above steps, since it is possible to remove the holes in the intermediate insulating film 6 and to remove the sintering once, the steps can be simplified, and at the same time the steps are not performed properly. Since the insulating film on the stable metal film is removed only once by etching, the bonding pad 5
An oxide film or an alumina film is formed on the upper surface, which reduces the possibility of a connection failure.

Further, the problem that the thickness of the specific bonding pad portion 5 becomes thin due to the battery effect is reduced by the number of times of etching. Further, the light shielding film 13
Is not left on the bonding pad portion 5, there is no need to consider the conductivity of the light shielding film 13, and the flexibility of the material of the light shielding film 13 is increased.
If an opaque insulating film is used as 3, even if a pinhole is generated in the intermediate insulating film 6, a short circuit does not occur between wiring metals, and the yield and quality can be improved.

[0032]

As described above in detail in the embodiments,
According to the semiconductor device manufacturing method of the present invention, the number of steps is reduced, and the quality and the production efficiency are improved. Further, according to the configuration of claim 2, even if a pinhole is generated in the intermediate insulating film, it is avoided that this becomes a sensor defect.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view sequentially showing steps of a method for manufacturing a semiconductor device according to the present invention.

2A and 2B are cross-sectional explanatory views sequentially showing steps of a conventional method for manufacturing a semiconductor device.

[Explanation of reference numerals] 1 semiconductor substrate 2 insulating film 4 metal wiring region 5 bonding pad portion 6 intermediate insulating film 7 scribe region 11 sensor light receiving portion 12 protective film 13 light shielding film 14 light shielding pattern

Claims (2)

[Claims] 1. A method of manufacturing a semiconductor device provided with a light-shielding pattern, the method comprising: forming a metal wiring pattern for connecting elements provided on a semiconductor substrate through an insulating film; and intermediate insulating on the metal wiring pattern. A step of forming a film over at least one main surface, a step of forming a light-shielding film over the intermediate insulating film over at least one main surface, and removing the light-shielding film leaving a region where light-shielding is necessary. And a step of forming a surface protective film made of an insulating material on the entire surface of at least one main plane of the light shielding film, and a portion of the protective film and the protective film in a portion where an insulating film such as a bonding pad portion or a scribe region is unnecessary. And a step of removing the intermediate insulating film, and performing each of these steps in the order described above. 2. The method for manufacturing a semiconductor device according to claim 1, wherein the light shielding film is made of an opaque insulator.