JPH06151802A - Formation of aluminum metallic pattern of solid-state image sensing device - Google Patents

Abstract

PURPOSE:To lower the resistance of a wiring pattern, to improve the light-shielding properties of a light-shielding pattern and to reduce the stepped section of a sensor region by changing the forming method of patterns. CONSTITUTION:A plurality of sensors 12, transfer electrodes 13, a wiring 14, etc., constituting a solid-state image sensing device 1 are formed onto a substrate 11, and these parts are covered with an insulating film 15 under the state, in which these parts are covered. A first aluminum metallic film 21 is formed onto the insulating film 15, a wiring pattern 32 as a lower layer is shaped in a wiring region 31 by the metallic film 21, and a light-shielding pattern 42 as a lower layer is formed in a light- shielding region 41 in a first process. The state, in which the wiring pattern 32 and the light-shielding patter 42 as each lower layer are covered, is brought and a second aluminum metallic film 22 is shaped onto the insulating film 15 in a second process. A wiring pattern 33 as an upper layer is formed onto the wiring pattern 32 as the lower layer by the metallic film, and the light-shielding pattern 43 as an upper layer is formed onto the light-shielding pattern 42 as the lower layer while a light-shielding pattern 52 is shaped under the state, in which the transfer electrodes 13 in a sensor region 51 are covered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming an aluminum-based metal pattern for a solid-state image pickup device.

[0002]

2. Description of the Related Art A conventional method for forming an aluminum-based metal pattern of a solid-state image pickup device will be described with reference to the process chart of FIG. As shown in (1) of FIG. 2, a plurality of sensors 62, a plurality of transfer electrodes 63, a plurality of wirings 64, etc. are formed on a substrate 61 as a plurality of patterns constituting the solid-state imaging device 1. Further, an insulating film 65 is formed on the substrate 61 so as to cover each sensor 62, the transfer electrode 63, the wiring 64 and the like. For example, the first aluminum-based metal film 66 is formed on the insulating film 65 by the sputtering method. After that, the portion indicated by the chain double-dashed line of the first aluminum-based metal film 66 is removed by photolithography and etching. Then, the remaining first aluminum-based metal film (6
In 6), the lower layer wiring pattern 72 is formed in the wiring region 71. At the same time, a lower-layer light-shielding pattern 82 is formed in the light-shielding region (commonly called optical black region) 81. At the same time, a lower layer light shielding pattern 92 is formed in a state of covering each transfer electrode 63 in the sensor region 91.

After that, the resist pattern (not shown) formed by the photolithography technique is removed by, for example, an asher process. Next, as shown in (2) of FIG. 2, a second aluminum-based metal film 67 is formed by, for example, the sputtering method. After that, the portion indicated by the alternate long and short dash line of the second aluminum-based metal film 67 is removed by photolithography and etching. Then, with the remaining second aluminum-based metal film (67), an upper wiring pattern 73 is formed on the lower wiring pattern 72. At the same time, an upper layer light shielding pattern 83 is formed on the lower layer light shielding pattern 82. At the same time, an upper layer light shielding pattern 93 is formed on the lower layer light shielding pattern 92.

In this way, the wiring pattern 74 is formed by the upper and lower wiring patterns 73 and 72, and the light shielding area 81 is formed.
The light-shielding pattern 84 of the upper and lower light-shielding patterns 83,
Formed at 82. The light-shielding pattern 94 in the sensor region 91 is formed by the light-shielding patterns 93 and 92 in the upper and lower layers.

[0005]

However, in the above-described forming method, as shown in FIG. 3, the light-shielding pattern 94 in the sensor region 91 has the light-shielding patterns 93, 92 in the upper and lower layers.
Therefore, the step between the film surface on the sensor 62 and the upper surface of the upper light shielding pattern 94 becomes large. Therefore, in order to form the flattening film for forming the on-chip lens, the transparent flattening film 100 must be formed thick. In this way, when the on-chip lens 110 is formed on the flattening film 100 having a large film thickness, the sensor 62
Since the distance between the on-chip lens 110 and the on-chip lens 110 becomes long, the loss of incident light increases and the sensitivity decreases.

In order to reduce the thickness of the light-shielding pattern 94, as described in the prior art, when the aluminum-based metal film is not formed in two layers but is formed of one thin aluminum-based metal film. Has a high resistance because the cross-sectional area of the wiring pattern is small. As a result, the signal transmission speed becomes slow. In addition, the light blocking performance in the light blocking region cannot be sufficiently obtained. Further, when it is formed of a single thick aluminum-based metal film, sufficient over-etching is necessary. As a result, the film loss of the insulating film at the bottom of the step increases.

The present invention provides a method for forming an aluminum-based metal pattern for a solid-state image pickup device, which enables a resistance of a wiring pattern to be reduced, a sufficient light-shielding property of a light-shielding pattern to be secured, and a step difference in a sensor region to be reduced. With the goal.

[0008]

The present invention is a forming method which is made to achieve the above object. That is, after forming a plurality of patterns constituting the solid-state imaging device on the substrate, the insulating film is coated so as to cover each pattern. Then, in a first step, a first aluminum-based metal film is formed on the insulating film, and then a lower-layer wiring pattern is formed in the wiring region of the solid-state imaging device with the first aluminum-based metal film.
A lower layer light shielding pattern is formed in the same light shielding region. Then, in a second step, a second aluminum-based metal film is formed on the insulating film so as to cover the wiring patterns and the light-shielding patterns of the lower layers. Then, using the second aluminum-based metal film, an upper wiring pattern is formed on the lower wiring pattern, an upper light shielding pattern is formed on the lower light shielding pattern, and the light shielding pattern is formed so as to cover the transfer electrodes in the sensor region. To form.

[0009]

Since the wiring pattern in the wiring region is formed of the first and second aluminum-based metal films, the wiring resistance becomes sufficiently low. Further, since the light-shielding pattern in the light-shielding region is formed of the first and second aluminum-based metal films, the light-shielding pattern obtains sufficient light-shielding performance. Further, since the light-shielding pattern in the sensor area is formed only by the second aluminum-based metal film, the step difference in the sensor area is reduced. Therefore, it is not necessary to form the flattening film thick.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to the process chart of FIG. As shown in (1) of FIG. 1, a plurality of sensors 12, a plurality of transfer electrodes 13, a plurality of wirings 14 and the like are formed on a substrate 11 as a plurality of patterns forming the solid-state imaging device 1. Further, an insulating film 15 is formed on the substrate 11 so as to cover each sensor 12, the transfer electrode 13, the wiring 14, and the like.

First, in the first step, a first aluminum-based metal film 21 is formed on the insulating film 15 by, for example, a normal sputtering method. After that, the portion indicated by the chain double-dashed line of the first aluminum-based metal film 21 is removed by the usual photolithography technique and etching. Then, the remaining first aluminum-based metal film (21) is used to form a lower wiring pattern 32 in the wiring region 31 of the solid-state imaging device 1. At the same time, a lower light shielding pattern 42 is formed in the light shielding region 41 of the solid-state imaging device 1.

Then, as shown in FIG. 1B, the wiring pattern 3 in the lower layer is formed by, for example, a normal sputtering method.
2 and the light shielding pattern 42 of the lower layer are covered,
A second aluminum-based metal film 22 is formed on the insulating film 15. After that, the portion indicated by the alternate long and short dash line of the second aluminum-based metal film 22 is removed by the usual photolithography technique and etching. Then, the remaining second aluminum-based metal film (22) is used to form an upper wiring pattern 33 on the lower wiring pattern 32. At the same time, the upper layer light shielding pattern 43 is formed on the lower layer light shielding pattern 42. At the same time, the light shielding pattern 52 is formed on the transfer electrode 13 in the sensor region 51, for example.

In the above forming method, since the wiring pattern 34 in the wiring region 31 is formed by the upper and lower wiring patterns 33 and 32, the wiring resistance thereof is sufficiently low. Further, since the light shielding pattern 44 of the light shielding region 41 is formed by the upper and lower layer light shielding patterns 43 and 42, sufficient light shielding performance is obtained. Further, the light shielding pattern 52 of the sensor area 51 is
Since it is formed of only the second aluminum-based metal film 22, the step difference between the upper surface of the insulating film 15 and the upper surface of the light shielding pattern 52 on the sensor 12 in the sensor region 51 is reduced. Therefore, when the flattening film is formed, it is not necessary to increase the film thickness.

[0014]

As described above, according to the present invention,
Since the wiring pattern of the wiring region and the light shielding pattern of the light shielding region are formed by the first and second aluminum-based metal films, the wiring resistance can be sufficiently reduced. Further, it is possible to sufficiently shield the light shielding area. Furthermore, since the light-shielding pattern in the sensor region is formed only by the second aluminum-based metal film, the step difference in the sensor region can be reduced. For this reason, it is not necessary to form the flattening film with a large thickness, and thus the flattening process is facilitated. Further, when an on-chip lens is formed, the loss of incident light can be reduced.

[Brief description of drawings]

FIG. 1 is a process drawing of an example.

FIG. 2 is a diagram showing a forming process of a conventional example.

FIG. 3 is an explanatory diagram of a problem.

[Explanation of symbols]

 1 Solid-State Imaging Device 11 Substrate 12 Sensor 13 Transfer Electrode 14 Wiring 15 Insulating Film 21 First Aluminum Metallic Film 22 Second Aluminum Metallic Film 31 Wiring Region 32 Lower Wiring Pattern 33 Upper Wiring Pattern 34 Wiring Pattern 41 Light Shading Area 42 Lower-layer light-shielding pattern 43 Upper-layer light-shielding pattern 51 Sensor area 52 Light-shielding pattern

Claims (1)

[Claims] 1. A solid-state imaging device comprising: forming a plurality of patterns constituting a solid-state imaging device on a substrate; then covering an insulating film so as to cover each pattern; and subsequently forming an aluminum-based metal pattern on the insulating film. A method of forming an aluminum-based metal pattern, comprising forming a first aluminum-based metal film on the insulating film, and then using the first aluminum-based metal film to form a lower layer wiring in a wiring region of the solid-state imaging device. A first step of forming a pattern and forming a lower-layer light-shielding pattern in a light-shielding region of the solid-state imaging device; and a step of covering the lower-layer wiring pattern and the lower-layer light-shielding pattern on the insulating film. After forming the second aluminum-based metal film, an upper-layer wiring pattern is formed on the lower-layer wiring pattern with the second aluminum-based metal film, and the lower-layer wiring pattern is formed. A second step of forming a light-shielding pattern of an upper layer on the light-shielding pattern and forming the light-shielding pattern in a state of covering the transfer electrodes in the sensor region of the solid-state imaging device. Method for forming metal pattern.